Newly discovered iron minerals could be the missing link in how water is stored in the deepest parts of Earth's mantle and transported to the upper layers, recent research reveals. The findings are crucial for understanding the mantle's motion, volcanic activity and the workings of other rocky planets, the study authors say.

The researchers discovered the iron minerals, called iron oxyhydroxides, by squishing mineral samples between two tiny diamond anvils while zapping them with a laser.

The two iron minerals are stable at the conditions found at the boundary between Earth's core and its mantle (the planet's middle layer), which is under "more than a million times the pressure we feel at the surface," Steve Jacobsen, a mineralogist and professor of Earth science at the University of Colorado Boulder who was not involved in the study, told Live Science in an email.

The new minerals contain as much as 15% water by weight. "If you add up all the H and O atoms in the formula and combine them into H2O, just a five-pound piece of the stuff would contain a pint of liquid water," Jacobsen added. "If this material existed in the early Earth, spread out across the base of the mantle, even just a few percent of it would potentially be enough to supply the formation of the oceans."

A tectonic mystery

Earth contains multiple layers, like an onion. The crust is the thinnest layer (the onion skin), and it moves around very slowly on top of a giant ocean of molten rock called the mantle (the juicy part of the onion). Deep in the heart of that ocean is the planet's core, like an onion's center, if the center of the onion were made of superheated iron and nickel crushed under the weight of a planet.

Water in the mantle makes the molten rock stretchier, which means the mantle can change its shape and convect. That's a big part of why Earth has plate tectonics ‪—‬ without water in the mantle, the material is too stiff to move around and drag the planet's crust with it. We know there's water in the mantle; however, we don't know exactly what the water in the mantle is doing.

There are two main theories for how water gets into Earth's mantle. The first is through subduction: When one tectonic plate sinks under another, it brings water from the surface into the mantle. The second is primordial water, left over from the planet's formation, that's stored near the boundary between Earth's core and the lower mantle.

The newly discovered minerals match both major theories for how Earth got its mantle water. They're dense enough to sink all the way to the bottom of the mantle, which fits with subduction and provides a way for water to enter Earth's core. The iron minerals are also strong enough to withstand the extremely high-energy impacts that they would have experienced if they were present while Earth was forming.

The mantle's convection could bring these minerals from near the core to close to the surface in large mantle plumes, where the minerals would melt and release their water, thus completing the water cycle in the mantle and contributing to volcanic hotspots at the surface. This process has implications for water cycles and theories of how other rocky planets and exoplanets ‪—‬ especially the weird ones that are mostly molten rock ‪—‬ formed.

Although the study, published Sept. 8 in the journal Nature Geoscience, doesn't prove that these minerals are taxiing water around the mantle, knowing that the iron minerals exist provides a pathway for the first time. The newly discovered minerals might also explain mysterious, extremely dense regions deep inside Earth ‪—‬the "ultra-low seismic velocity patches we see sitting on top of the core-mantle boundary," Jacobsen added.

What is Earth made of? Find out with our inside Earth quiz!

Earth's continents are losing fresh water much faster than scientists thought, mostly because aquifer pumping in regions like northern India, southern Iran and parts of the U.S. is 45% more pronounced, on average, than previous estimates suggested, new research shows.

The study used satellite data to map freshwater trends across the globe between 2002 and 2025. Thanks to a high-resolution rendering method, researchers revealed regional gains and reductions in terrestrial water storage that were 33% more marked, on average, than in previous studies. The amount of fresh water lost was much higher than the gains overall, highlighting the urgent need for better water management to stave off a global water crisis.

"It has become very dire in a lot of places," Hrishikesh Chandanpurkar, a hydrologist and the co-founder of the nonprofit Evergreen Resilience Institute, who was not involved in the study, told Live Science.

The study also attributed the changes in freshwater storage to different human and climate drivers, said first author Mary Michael Forrester O'Neill, a researcher at the University of Maryland's Earth System Science Interdisciplinary Center and the Hydrological Sciences Laboratory at NASA's Goddard Space Flight Center.

"Earlier studies could see broad patterns of long-term freshwater loss or gain but couldn't reliably tell how much was due to human activity versus climate swings, in part due to resolution limitations," Forrester O'Neill told Live Science in an email. "This study sharpened the picture and used geostatistical methods to rank the impacts of human causes, like irrigation and dam building, against climate factors, like rainfall and drought."

The researchers found 94 regions with above-background shifts in freshwater storage, 40 of which were influenced mainly by human land or water use, rather than climate variability and global warming. The team then focused on these 40 hotspots to pinpoint exactly where people can act to conserve water.

"Water managers and downstream communities need to know which aquifer, reservoir, or irrigation district is responsible for a given trend in large-scale freshwater storage, not just that 'somewhere in this country, water is being lost,'" Forrester O'Neill explained.

Freshwater gains in 22 regions were due to rain-fed agriculture, irrigation with surface water, reservoir impoundment and deforestation, which decreases evapotranspiration and plants' groundwater consumption, according to the study. In contrast, freshwater losses in the remaining 18 hotspots were caused by irrigation with groundwater and the construction of canals, diversions and other water infrastructure.

The findings, published Sept. 14 in the journal PNAS, show that human water use is a significant driver of water storage changes on every continent except Australia and Antarctica, where climate factors are more influential, O'Neill said. Local freshwater gains and losses may cut freshwater availability downstream or in the surrounding region, she and her colleagues noted in the study.

One example of a region that gained fresh water in the study is the area of central Russia that hosts the Boguchany Reservoir, a giant artificial lake that was filled in 2012 after the construction of a hydroelectric dam. And three stark examples of places that lost fresh water are northern India, southern Iran and the southern High Plains (a region at the intersection of Colorado, Kansas, New Mexico, Oklahoma and Texas), because these regions host major breadbaskets that tap aquifers for irrigation, O'Neill said.

The results are concerning because the places with the worst groundwater depletion overlap with areas that irrigate crops unsustainably, O'Neill said. Previous research shows that critical food-producing regions ‪—‬ such as the U.S. High Plains, California's Central Valley, northern India, Pakistan, North China and the Fertile Crescent ‪—‬ consistently overuse groundwater. "Within these regions, we found the pace of depletion is considerably more severe than earlier estimates suggested, reinforcing food security concerns," she said.

One of the novelties of the paper is its very high resolution, said Chandanpurkar, who last year led a study describing "mega-drying" regions across the world and co-authored a report on continental drying. The new study used data from NASA's Gravity Recovery and Climate Experiment (GRACE) mission and its Follow-On successor (GRACE-FO), which have measured subtle redistributions of mass on Earth. But unlike previous studies, the new research resolved the data in high resolution, he said, like correcting blurry vision with glasses.

"This is not a brand-new method, but it's the first time they're applying it to these regional hotspots and then trying to figure out what they mean," Chandanpurkar said.

Scientists already knew that groundwater depletion and other human water uses are "quite staggering," and this study is a reminder that continental drying is "a very big deal," Chandanpurkar said. "Water is really undervalued," he said. "Giving it its proper dues would be essential for this [freshwater loss] to really be acknowledged by leaders and economists."

It's impossible to say exactly how many years or decades humans can go on consuming this much fresh water before it runs out, partly because the climate can be unpredictable and partly because it's hard to tell how much water remains in Earth's reservoirs, Forrester O'Neill said.

"GRACE satellites measure the rate of change in water mass, not the total volume stored in an aquifer, so we have no independent basis for estimating time to depletion or a timeline for systems to collapse," she said.

However, there will come a point when the cost of pumping groundwater, for example, will be too high to pay in some regions. Water table declines of just a dozen feet (a few meters) or so can cause a substantial share of wells to run dry, research shows, and the expense of drilling deeper will affect at-risk communities most of all, Forrester O'Neill said.

"We are most concerned about the rising cost and inequity of continuing to reach water that keeps retreating deeper underground, paired with strain on existing surface water resources," she said. "Of course, water-scarce regions exhibiting acute groundwater depletion are at risk, like Iran, Saudi Arabia, Syria, Türkiye, Iraq, and Libya. Another one to keep an eye on would be Mexico, simply because of the documented, progressively increasing well depth paired with the observed terrestrial water storage loss."

There's a commonly cited idea that water in a drain swirls in opposite directions in the Northern and Southern hemispheres. But is there any truth to it? When you pull the plug from a bathtub, does the water circle one way in New York and the other way in Sydney?

Although the idea is based on a real scientific principle, you probably won't see it play out in a small drain in your house, experts told Live Science.

The Coriolis effect

The idea that water spins in opposite directions in the Northern and Southern hemispheres stems from a phenomenon known as the Coriolis effect. When something, including air or water, moves across Earth as it rotates on its axis, that substance appears to curve because the ground beneath it is rotating at different speeds in different places. Points close to the equator move faster than points near the poles because they have a bigger circle to travel in the same 24 hours.

Over the immense distances covered by weather systems and ocean currents, that small deflection can accumulate and become important. The key words here are "immense distances." The Coriolis effect is weak, so it needs enough time and space to produce a noticeable change. Storms and weather patterns can persist for days and stretch across hundreds of miles. But water in a sink, bathtub or toilet has only seconds to move before disappearing down the drain.

"You always need to think about the right timescales and length scales," Susanne Horn, a professor of numerical and mathematical fluid dynamics at Coventry University in the U.K., told Live Science.

At your bathroom's scale, seemingly trivial details take control. The water may already be rotating slightly because of how it entered the basin, how somebody moved in the bath or how the plug was removed. The sink and drain are unlikely to be perfectly symmetrical, which can also play a part, and the design of a toilet deliberately guides its water. All of these factors are more influential on your basin than the Coriolis effect is. (In other words, that episode of "The Simpsons", which features Bart investigating drainage direction in Australia versus the U.S., got it wrong.)

Consequently, the same sink can drain clockwise on one occasion and counterclockwise on another, depending on the variation of these variables on any given day; the direction depends principally on how the water was introduced and the geometry of the container and drain, according to the Library of Congress.

So, although the Coriolis effect behind the claim is real, the water in a bathroom drain is normally overwhelmed by much stronger influences.

How to see the Coriolis effect in action

To make Earth's rotation ‪—‬ and, thus, the Coriolis effect ‪—‬ matter in a drainage experiment, Horn said, "there are essentially two tricks: let it drain very slowly, or make it much bigger."

Fluid dynamicists describe this using the Rossby number, which compares a flow's inertia with the influence of the planet's rotation. A small Rossby number indicates the Coriolis effect is important; a large one means the flow is moving too quickly or across too short of a distance, for Earth's rotation to have much influence. A typical household drain falls firmly into the latter category. In Horn's words, it "doesn't feel rotation."

Still, there are ways to see the Coriolis effect in action. In a meticulously designed experiment researchers suppressed those larger disturbances to give the Coriolis effect enough time to emerge.

In the 1962 experiment, described in the journal Nature, an MIT researcher used a large, carefully prepared tank that removed residual movements in the water before it drained. The water eventually developed the counterclockwise rotation predicted for the Northern Hemisphere.

Three years later, in another study published in Nature, researchers at the University of Sydney published a Southern Hemisphere counterpart. After taking similarly stringent precautions against outside disturbances, they observed the predicted clockwise rotation. The two experiments demonstrated that Earth's rotation could select the direction of a draining vortex — but only under extremely well-controlled conditions. In other words, the Coriolis effect appears only once you've removed practically every other variable.

That is very different from saying every sink or toilet flows in the same direction according to which hemisphere they're in. In normal plumbing, the drain's shape, the water's starting motion and the way it is released are all far more influential.

"Just ask yourself whether what you're looking at happens slower than Earth's rotation and for long enough, only then does the Coriolis force really start to matter," Horn said.

Brazil is home to some of the world's largest aquifers, yet many of those groundwater stores — which provide 55% of the country's water — have shrunk so much over the past 25 years that they face irreversible damage. This groundwater depletion has been caused by drought, increased water evaporation due to climate change, and pumping for human consumption, new research suggests.

Most of the world's soybeans, sugarcane, oranges and coffee — as well as a big proportion of the world's cotton and corn — are grown in the areas with the most depleted aquifers, so the dwindling groundwater supply could have ripple effects for food markets around the world, including in the U.S.

The depleted aquifers may also collapse river systems that produce hydroelectric power for Brazil, forcing the country to turn to coal or biomass for electricity, experts told Live Science.

Groundwater declines probably won't lessen total agricultural production in the next 10 to 20 years. "The concern is what happens if these trends persist for several decades," study first author Augusto Getirana, a researcher in the Hydrological Sciences Laboratory at NASA's Goddard Space Flight Center, told Live Science in an email. "Brazil is one of the world's major breadbaskets, so its water security has consequences well beyond the country itself."

A clear geographical contrast

Brazil holds the world's largest renewable freshwater reserves by country, mostly thanks to the Amazon Basin and its rainforest ecosystem. However, compared with countries like the U.S. and India, which have thousands of groundwater measuring sites, Brazil's network of monitoring wells is extremely sparse. Therefore, for the study, Getirana and his colleagues trained artificial intelligence (AI) models to fill in the gaps in the data.

The researchers fed the models measurements from 398 monitoring wells, satellite data showing tiny shifts in gravity resulting from groundwater changes, and information about the geology and land cover in different areas, among other datasets. AI reconstructed monthly groundwater level changes between 2002 and 2023 across different aquifers in Brazil at a resolution of about 6 miles (10 kilometers), Getirana said.

"We then reconstructed groundwater levels to estimate aquifer recharge — how much water reaches and replenishes the groundwater system — throughout the country," he explained.

The results, which were published June 3 in the journal Science Advances, showed severe, persistent groundwater losses in parts of central, northeastern and southeastern Brazil — including portions of the São Francisco, Paraná, Southeast Atlantic and East Atlantic basins, which together cover 760,000 square miles (1.97 million square kilometers), or about 23%, of Brazil's land area.

Some of Brazil's most critical aquifers went years with no recharge. By contrast, the Amazon Basin and parts of southern Brazil showed either no change or localized groundwater gains attributable to shifts in rainfall and natural climate variations, Getirana said.

"There is no single trend for the entire country," he said. "We found a clear geographical contrast."

Climate change is the culprit

The study didn't attribute groundwater changes to specific pressures, but it is clear from the data that climate shifts played a major role in the observed patterns, Getirana said. Several of the sharpest declines in aquifers came after prolonged droughts and major climate events, such as an El Niño cycle between 2015 and 2016.

Due to patchy monitoring, it is difficult to untangle and quantify the impacts of agriculture, industry and households on groundwater levels. However, the results revealed a substantial overlap between groundwater losses and areas with intense irrigation, urban and industrial demands, mining, land conversion and high well density, Getirana said.

"The most scientifically defensible interpretation is therefore that climate creates the underlying water deficit, while extraction and land-use changes are probably amplifying its magnitude and duration in heavily used regions," he said.

Javier Tomasella, an environmental scientist and hydrologist at Brazil's National Institute for Space Research who was not involved in the study, agreed that the main cause of aquifer depletion in Brazil is climate change.

"Droughts are lasting longer and becoming more intense in Brazil, and this is affecting most of the country, particularly the central area and the Northeast of the country," Tomasella told Live Science. Harsher droughts reduce groundwater recharge and create a higher demand for water, meaning people extract more from aquifers during dry spells. "This is why the impact in irrigated areas is much higher," he said.

The findings suggest that if droughts intensify over the next few decades, major agricultural regions in Brazil could run out of water to grow certain crops. Groundwater provides a buffer when rainfall and surface water resources become unreliable, especially for agriculture and municipal water supply, Getirana said.

The worry isn't so much that aquifers will dry up completely but rather that water levels will drop so low that it will become too expensive to pump water compared with the returns from producing crops.

"This is the same type of progression already observed in intensively exploited aquifers such as the High Plains and [Central] Valley systems in the United States and aquifers in northern India and Bangladesh," Getirana said. "The water does not necessarily disappear overnight; it progressively becomes harder, less reliable and more expensive to access."

Supply-chain risks

Farmers will likely adapt to smaller water supplies by switching water-intensive crops, such as soybeans, to less-thirsty ones, such as corn and wheat, Tomasella said. Some may do this during the dry season to save water, as is already common in regions such as northern Paraná that have a "double-crop" system. But if current market conditions hold, farmers' decisions about what to grow will ultimately depend on how much money they can make from crops while covering extra irrigation costs, he said.

The total production of mostly rain-fed crops like soybeans and corn likely won't be affected any time soon, but the balance of these crops may change, Tomasella said. Conversely, the total production of irrigated crops such as coffee, sugarcane and oranges may decline, "but that depends on how droughts will evolve in the next two decades," he said.

Countries that rely on food imports from Brazil might experience supply disruptions, but the scale of these is hard to predict. The most-exposed country is probably China, because it imports roughly 80% of its soybeans from Brazil, Getirana said. The U.S. and Europe may see declines in imports of coffee, sugar and oranges, while Asia and the Middle East could be affected through cotton and corn, he added.

"The United States alone relies heavily on Brazil for coffee and orange-juice imports," Getirana said.

Assuming market conditions don't change, it's unlikely there will be a decrease in Brazilian beef production, because demand for beef is so high, Tomasella said. If anything, he said, beef production will increase, because Brazilian farmers haven't yet maximized the number of cattle per acre of pasture. However, cattle do emit huge amounts of methane, which is a powerful greenhouse gas, he added.

Ripple effects

The study has implications beyond agricultural impacts, because aquifers are connected to river systems. Groundwater declines could cause rivers to dry up, and this would hit Brazil's hydropower network, which supplies 60% of the country's electricity, Tomasella said.

The alternative to hydropower is burning fossil fuels and biomass to produce electricity, he said. This comes with huge carbon dioxide emissions, which would worsen climate change and further amplify Brazil's water issues.

In the short term, groundwater losses are more likely to affect drinking-water supplies in big Brazilian cities like Rio de Janeiro and São Paulo than they are to impact agriculture, Tomasella noted.

"If droughts intensify, it might reach a point where you have to make very tough decisions," he said. "The real question is, 'Is this the new normal?' If this is the new normal, then we are in very deep trouble."

This article was originally published by Yale Environment 360.

Near-extinct oryx are returning. Farms are prospering as irrigation water reaches fields for the first time in decades. Farmers are even nurturing new trees on their land. Once a byword for drought and famine, the African Sahel region on the southern flank of the Sahara Desert now has more water than it has for decades. Wells are filling as water tables have risen by 13 feet or more in places. Lake Chad, which was one of Africa's largest expanses of water before shriveling during the droughts, is recovering.

Over years of drought in the late 20th century, the sun hard baked the soils of the Sahel. Now, erratic but extreme rains are returning to this semi-arid region, causing lethal floods but also replenishing rivers, filling desert depressions, restoring water to dried riverbeds known as wadis, and sluicing rainwater off impermeable soils directly into aquifers. The process began in the 1990s but has accelerated in the past five years.

"Across the Sahel, from Ethiopia to Senegal, we have evidence of increased terrestrial water storage," says Richard Taylor, a hydrogeologist at University College London who has led ground teams investigating the relationships between climate, land use, and groundwater recharge in the region.

But increased rainfall since the drought years of the 1970s and 1980s explains only some of the rewetting of the Sahel. It cannot fully account for the transformation, say researchers. Also driving the rewetting, they posit, are changes to the land surface, ranging from the internationally funded Great Green Wall project to the revival of traditional water harvesting methods and the chaos caused by jihadist militants, which has led to the abandonment of irrigation projects that once emptied rivers of their flows.

Much remains unclear in these remote lands on the edge of the Sahara Desert, but the trend seems set to be long-term, with climate scientists saying more — and more extreme — rainfall is on the way in the 21st century. As underground water reserves revive, some are forecasting an agricultural renaissance.

The Sahel is a band of semi-arid land around 500 miles wide that stretches across North Africa, from Senegal in the west to Ethiopia in the east, with a fast-growing population above 150 million. It is a transition zone between the Sahara Desert in the north and savanna grasslands and coastal forests to the south. Water is everything in the Sahel. Its rains are critical to human survival, but they have been sporadic and unpredictable since the close of a humid era around 5,000 years ago.

How much rain the Sahel gets depends on the West African monsoon, a wet wind that sweeps north from the Gulf of Guinea between June and September, and on how far the monsoon penetrates into the interior. Whether it reaches the 15th parallel north of the equator or stalls at the 10th parallel make the difference between a good year and a failed harvest, say hydrologists.

During the droughts of the late 20th century, as the monsoon repeatedly fell short, up to a million people died of hunger and disease. But now, with a strengthening monsoon, there is talk among scientists of the Sahel being on the verge of a new humid era.

That is good news for wildlife. With wadi systems reviving in Chad's Ouadi Rimé-Ouadi Achim nature reserve, conservationists are documenting resurgent numbers of aardvarks, porcupines, badgers, and foxes, and the successful reintroduction of the scimitar-horned oryx, which was once declared extinct in the wild but now numbers more than 600 individuals. Elsewhere, West African giraffes are browsing on verdant vegetation in areas from which they had disappeared.

As the rains return, farmers have boosted crop yields by nurturing the natural regrowth of some 200 million trees on formerly treeless fields in southern Niger, according to former World Resources Institute geographer Chris Reij. And, supported by new aid programs such as the World Bank's regional recovery program PROLAC, they are re-establishing small-scale irrigation systems by tapping groundwater around resurgent oases in Chad, Niger, and Cameroon.

"In the past … there was not enough water to irrigate crops, and our harvests were meager. Now our lives have changed," Achta, a farmer in Chad, said last year. She now has water to plant on four times as much land and has doubled her onion crop. The Bank says her story "reflects a broader transformation across the Lake Chad basin."

Most places in the Sahel are seeing more rainfall. And that rain has become concentrated in extreme downpours from clusters of violent thunderstorms, known to meteorologists as Mesoscale Convective Systems, that occasionally bubble up during the monsoon season. Sahelian storm clusters are now rated as some of the most powerful on the planet, and they deliver most of the region's rainfall. There has been a threefold increase in the frequency of extreme storms since the 1980s, according to a recent analysis.

Why the revival of the rains? An assessment published in 2021 by the U.N.'s Intergovernmental Panel on Climate Change found "high confidence" among climate scientists that it is a result of strong warming in the North Atlantic, caused by a combination of global heating and a reduction, in Europe and North America, of sulphate aerosols from coal burning, which once created a thin haze that cooled the ocean. That cooling prevented the northward migration of the West African monsoon into the Sahel, resulting in drought. But the clean-up has warmed the ocean and pulled the monsoon back into the Sahel, strengthening its ability to produce deluges.

The effects of these mega-storms are especially challenging in a region more used to disasters caused by the absence of rain. Niger, one of the world’s 10 poorest countries, saw tens of thousands die from famine during the late 20th century droughts. Now, it sees more deaths from floods than droughts. Fierce storms during the 2024 monsoon season inundated the capital, Niamey, and in rural areas washed away more than 150,000 mud-brick homes.

Sudden downpours are initially destructive, but they are a boon to underground water reserves. Falling onto compacted ground, the water does not initially infiltrate the soil but rushes into rivers and dry wadis, which speed the water's flow into aquifers.

Hydrologists say that this indirect infiltration is most intense after heavy storms. "In some locations, rainfall intensity is more important than the annual rainfall amount in determining the magnitude of groundwater recharge," says Taylor. This intensity, he says, is a major cause of the rapid rising of water tables — especially since, in the Sahel, most water drains not to the ocean but inland to depressions and lakes.

Not only are new ponds forming across the formerly arid lands; ancient networks of wadis are being restored. And Taylor's network of researchers has found wells across the region refilling. Mean water tables in much of Niger have risen by some 13 feet, indicating a 15 percent increase in aquifer reserves.

This local data is now being corroborated by analysis from satellites that measure changes in land mass by tracking subtle changes in gravitational force from the land below. NASA's Gravity Recovery and Climate Experiment mission has found a sharp increase in gravitational force across the Sahel in the past two decades that hydrologists attribute to growing terrestrial water storage.

But rainfall and its intensity are only part of the story. Events on land also play a part.

Environmentalists have long held that the encroachment of agriculture into the Sahel during the 20th century caused "desertification" by removing natural vegetation, destroying soils, and allowing the advance of desert sands. But hydrologically, the effect may be the opposite because some crops can actually help the land retain water.

All vegetation absorbs moisture from the soil before transpiring it into the air. But shallow-rooted African grain crops such as millet and sorghum transpire less moisture than the deeper-rooted grasses they replace, leaving more moisture in the soil.

An amplifying factor is the drought-driven crusting of soils, which has increased runoff by around 50 percent in the central Sahel in recent decades. Analysis by Christophe Peugeot, a hydrologist at the HydroSciences laboratory at the University of Montpellier in France, found that the droughts "have permanently transformed the region's soils… fueling today's floods."

Much of this runoff ends up in Lake Chad, on the border between Nigeria, Cameroon, Chad, and Niger, which drains an area almost six times the size of California. The lake's dramatic demise became a totemic image of the late 20th century hydrological decline of the Sahel. But less well known is that the lake is now recovering, as water inflows increase. Hydrogeologists at the University of N'Djamena in Chad report that in 2024 it swelled to a peak of more than 9,000 square miles, almost as big as in the 1960s and 10 times its size in the mid-1980s.

This growth is partly masked by large areas of saturated vegetation in the lake that do not show up in satellite images, say hydrologists. But as the lake grows, the aquifer beneath is also refilling.

Some researchers argue that deliberate efforts to capture rain in soils can also help explain the rising groundwaters across the region. One such effort is the Great Green Wall. Originally planned as a barrier of planted trees to prevent the advance of the Sahara, it has morphed into more grassroots efforts to control soil erosion by capturing rainfall and improving soil moisture, all of which can improve infiltration underground.

Many such projects revive traditional water-harvesting techniques, including the placement of stones along hill contours, digging small holes known as "zai pits" amid crops, and forming crescent-shaped mounds around trees.

Alpha Lo of the Climate Water Project, who highlighted the restored Sahelian groundwaters in a recent online analysis, argues that such techniques are "the primary reason." But most researchers believe that, while locally effective in nurturing trees or crops, they are not happening at sufficient scale to explain the region-wide resurgence.

A final suggestion is that humans are extracting less water from rivers, leaving more to eventually infiltrate into aquifers. One driver of this trend is the decline of big irrigation projects that were constructed during the drought years to boost food production. For instance, Cameroon once largely emptied the River Logone, historically the biggest single source of water flowing into Lake Chad, to grow rice. But the SEMRY irrigation project reportedly diverts much less water now, due to poor management, aging infrastructure, and the outmigration of farmers.

In areas around Lake Chad, farmers have also abandoned their irrigated fields because of Boko Haram, a militant jihadist group that continues to terrorize communities. Timmo Gaasbeek, food security policy officer at the Netherlands Ministry of Foreign Affairs, says the chaos in northern Nigeria "means that the water in the rivers is not caught upstream, and continues to flow into Lake Chad, where it contributes to higher water levels and more groundwater recharge."

Most climate models predict a further increase in annual rainfall in the coming decades, due to global heating and the banishing of cooling aerosols from the North Atlantic. Taylor predicts that "the Sahel will experience particularly marked increases in extreme rain" that will "serve to increase groundwater recharge."

Peugeot says that "the increased availability of water in valley bottoms could promote the development of irrigation, offering new prospects in several Sahelian regions." Buoyed by such predictions, Nigeria is looking to restore the 165,000-acre South Chad Irrigation Project on the former shores of Lake Chad, which has long been abandoned for want of water.

But the road ahead will not be straightforward. Sahel rains will continue to be erratic on all timescales. Most immediately, climatologists are predicting that this year's strong El Niño event could deliver drought in the eastern Sahel, but bumper rains and more floods further west.

The Caspian Sea, the world's largest inland body of water, is in major trouble. Since the mid-1990s, this saline lake, located between Europe and Asia, has lost an area nearly the size of Sicily. But until now, it wasn't clear why.

Researchers finally provided answers in a study published June 5 in the journal Earth's Future. Using ground- and satellite-based observations, they connected falling water levels to a drastic drop in river inputs from Iran, Turkmenistan, Azerbaijan, Kazakhstan and Russia, all of which border the Caspian Sea.

The team particularly highlighted losses from Russia's Volga River, the longest river in Europe, which supplies roughly 80% of the Caspian's inflow.

To find out why the Volga is discharging less water into the Caspian Sea now than it did 30 years ago, we spoke with Amir AghaKouchak, a co-author of the study and professor of civil and environmental engineering at the University of California, Irvine.

AghaKouchak, who directs UC Irvine's Center for Hydrometeorology and Remote Sensing, explained why river inputs have dropped and how decades of water withdrawals have put the Caspian Sea on a path to collapse. He also touched on a solution to this crisis — and revealed why Russia's hunger for ammunition to attack Ukraine is making it harder to save the Caspian Sea.

Sascha Pare: Falling water levels in the Caspian Sea have been attributed to natural variability, and more recently, there's been a focus on climate change and increased evaporation due to rising temperatures. But what did the results of your study show?

Amir AghaKouchak: People quickly jump to conclusions about climate change. Of course, that is important, but it cannot explain the change that we have observed. Over the last 30 years, water levels in the Caspian Sea have shrunk by around 2 meters [6.5 feet] or so. Just to put things in perspective, this translates to about 24,000 square kilometers [9,300 square miles] of sea area loss — about 5%. When we look at drivers, we notice that rainfall hasn't changed significantly over the lake and upstream, so the decline cannot be explained simply by changes in rain.

Evaporation has increased, so it explains maybe about one-third of the change. There is less water in the lake, and that indicates there's probably some water lost along the way. We don't have a lot of human-related data ‪—‬ for example, water withdrawal for irrigation or groundwater wells. That area is very difficult; the countries are not open to sharing data. A lot of our results are based on looking at proxies. Our interpretation is that temperature caused about 30% of the change and the rest is probably because of human activities.

SP: Which human activities does your research suggest are responsible for the Caspian Sea's decline?

AA: Several of the countries on the Caspian Sea have built large dams — Russia, for example. They are all desperate for hydropower. All of the countries around the lake [have also built infrastructure to supply agriculture], and one reason is that they want to create jobs and improve the local economy. Water demand is increasing in all those countries around the Caspian Sea. It's not surprising to see lakes drying or groundwater levels falling.

It's hard to find data about how much water countries are using; they keep data very private, especially places like Russia. We don't have detailed information, but the Volga-Don Canal in Russia is one of the projects that is contributing to this crisis. [Editor's note: The Volga-Don Canal is a ship canal that connects the Volga and Don rivers at their closest points.]

But we cannot blame this whole thing on that. We have to be careful with our language; we can't say one project is responsible. Most likely, this is the collective impact of many different small withdrawals from here and there, overall contributing to a significant decline in the Volga River outflow into the lake. In the paper, we have different rivers, but the Volga dominates because it's the largest river. The Volga has a higher impact than all the other rivers combined. There are lots of demands along that river basin.

SP: Did you expect human activities to play such a big role, or were you surprised?

AA: We did not have any expectations at the beginning. In fact, when we started this project, I reached out to a lot of colleagues from neighboring countries around the Caspian Sea. We didn't want to do it on our own, sitting in California, looking at another area of the world, without having local people involved. If you look at the co-authors, you see people from Azerbaijan, Iran, Kazakhstan — so, we have local experts. We thought this was really important to have those perspectives. I didn't want to reflect the opinions of only one research group. What we have here is the collective opinion of people who have not met in person; we only exchanged emails to look at the results, and then we came up with those conclusions.

We do have a Russian involved, but not from an official Russian institution. I thought this was really important, because there's more back-and-forth [with a large group of people]. If two people have to convince themselves of an idea, it's much easier than with 20. Also, we brought in people from other countries who had projects in the area; for example, there is one group from Finland and another group from Germany. We tried to come up with something that this large group of people could agree on. It was not easy, but it worked out.

SP: What is the worst-case future scenario for the Caspian Sea if shoreline countries fail to decrease their water demands?

AA: My concern is that, in the same general area, we have the Aral Sea, which is now about 5% to 10% of what it used to be, and Lake Urmia, in northwest Iran, that has also shrunk really fast and is now very small, with low levels of ecological activity. So we have two smaller lakes in a very similar climate that, from an ecological perspective, are dead. Because we have seen those degrade, we have to consider that this is the worst-case scenario for the Caspian Sea, too.

The Caspian Sea is much, much bigger. I hope it doesn't happen, but it's on the same path. Again, it's much larger, so it would probably take 100 years [to shrink as much as the Aral Sea and Lake Urmia], even with the current trend. But because we have seen those lakes shrink really fast, it deserves attention. Due to the size of this lake, the potential impacts will be huge. Even if 20% of the Caspian Sea dries out, the consequences will be very significant. It would be a disaster.

SP: You mentioned that drying lakes can become ecologically "dead." What other impacts could the Caspian Sea's falling water levels have on the surrounding landscape and people?

AA: The lake's retreat will expose the lake bed, and because it's saline, you have all kinds of minerals that will be exposed. With the next strong wind, they will go into the air. The health impacts include respiratory diseases, and even eye diseases, that are linked to salt minerals in the atmosphere. Those are the immediate consequences. Additionally, those minerals can travel long distances. In general, salt deposition on agricultural land reduces productivity. It takes a while, but if those lands are exposed for a long time, this will have an impact on the agricultural sector in those areas, which means potential food security issues. We don't exactly know what those materials are on the lake bed, so it's hard to know precisely what the consequences will be.

There is also serious shipping happening in this region. Right now, most of the shrinking is happening in the Caspian Sea's northern part, which is shallower [than the rest of the lake]. The drop in water levels is about 2 meters, and you can imagine that if you have a port and water levels drop more, you won't be able to operate. You'll need to extend your shipping routes southward; you'll need to invest and spend a lot of money to use other ports and docking sites. We have evidence of that around the Aral Sea and also Lake Urmia. There used to be these docking sites and ports, but those are now far away from the water.

SP: What must bordering countries do to save the Caspian Sea and prevent these negative effects?

AA: Demand management is absolutely critical. Demand management doesn't get a lot of attention, because unlike big projects that make the news, management means you have to cut things and do things that people don't notice. Some people argue that politicians don't show a lot of interest in demand management, but it's something that we have control over. The technological opportunities are there.

But when you look at that area, there is a big war ‪—‬ so probably it's not the priority to invest in management. There are a lot of things that we don't talk about in the paper that are relevant. I recently learned through discussions with people from the region — this is something that came to us from co-authors and collaborators — that many countries in that area grow cotton, which uses a lot of water. It has a lot of applications, but apparently, one of them is military. Cotton is used to produce ammunition. Russia needs a lot of ammunition, so not only are they growing it themselves, but they also bought neighboring reserves from Uzbekistan and Kazakhstan. So now, even those countries have an incentive to grow more cotton. This is driving more irrigation, more groundwater extraction, more surface water depletion, and probably more impacts on the Caspian Sea.

This interview has been condensed and edited lightly for clarity.

Fifty years after Southern California's Salton Sea formed due to an engineering mishap in 1905, the giant salt lake became a booming vacation destination. Nicknamed the "miracle in the desert," the lake offered watersports and boating, while its shores were lined with yacht clubs, vacation homes, shops and nightclubs.

However, by the 1970s, the Salton Sea had begun shrinking due to high evaporation rates and flow reductions in the Colorado River, which had fed the lake. The lake's retreat exposed muddy sediments imbued with pesticides and other agricultural chemicals from large cotton, alfalfa and vegetable farms in the Imperial and Coachella valleys.

Today, the Salton Sea is a ghost of its former self, but the lake looms larger in the lives of local residents than ever before. Its shrinking shoreline releases toxic particles so tiny that they can penetrate deep into human lungs and enter the bloodstream. Exposure to these particles can raise the risk of a range of respiratory and cardiovascular conditions, including asthma, impaired lung function and heart attacks.

The communities most affected by this pollution are low-income, racial and ethnic minorities that, for socioeconomic reasons, cannot move away or adequately protect themselves.

A study published July 1 in the journal BMC Environmental Science reveals just how bad living conditions are for some communities near the Salton Sea. The authors examined air quality and respiratory health in Latinx and Indigenous Mexican families in the Eastern Coachella Valley, finding that families must change their daily routines to protect themselves from harmful dust events.

To find out more, we spoke with study co-author Ann Cheney, a professor of social medicine, population and public health at the University of California, Riverside School of Medicine. Cheney, who oversees a free clinic for underserved minority communities in the Eastern Coachella Valley, described the daily struggles of families living near the Salton Sea and some of the measures that are needed to improve their quality of life.

Sascha Pare: The Salton Sea has shrunk by 65 square miles (168 square kilometers) and dropped by 14.6 feet (4.5 meters) over the past few decades. Why is that, and how does it affect local residents?

Ann Cheney: The Salton Sea occupies an ancient lake bed that, over the millennia, has been filled, and then dried up again. In the early 1900s, because of an engineering mistake, part of that lake bed filled, and it created the Salton Sea. [Editor's note: The sea formed when Colorado River floodwater breached an irrigation canal that was under construction in the Imperial Valley.]

Then, over decades, there were changes in the composition of the sea because the main source of water was agricultural runoff. The sea is located in the inland southern Californian desert region. In the 1940s and 1950s, there was a boom in agribusiness. This remade the landscape, and all of those chemicals and pesticides from the agricultural land seeped into the lake bed.

With [water management] decision-making around the Colorado River waters, that then meant that another source of water, which had been the Colorado River, ceased to enter into the Salton Sea. 2018 was the last time that water from the Colorado River touched the Salton Sea.

Because there is the primary source of agricultural runoff going into the sea and no new fresh water coming in — and with climate change [boosting evaporation] — it's created this environment in which you have a drying sea. Over decades, there have been chemicals and heavy metals seeping into the playa [dry lake bed], and now it's exposed. It's the desert, so there's a lot of dust storms, and the winds take the exposed playa and bring it into the air, which is then breathed by the local residents.

For me, what's most concerning is that the local residents who are most affected by the poor air quality are Latinx and Indigenous Mexicans, many of whom are undocumented and have very little political voice.

SP: You asked caregivers of children with asthma and other respiratory conditions to document their experiences of living near the Salton Sea. What did those submissions reveal?

AC: When I first started doing this work, I thought about it as solely the Salton Sea [affecting people]. But it's the environment in which the Salton Sea is one contributor to poor air quality [that impacts local residents].

The caregivers perceive the Salton Sea as being a contributor to the poor respiratory health of their children. But also, this area has many disenfranchised communities that are interspersed on tribal lands, and there are different rules on these tribal lands. There is a lot of dumping and a lot of burning of trash. What we heard from caregivers is that it's not just the exposure to the toxic dust, but also the fires [that are causing issues].

In that article that we published [July 1 in BMC Environmental Science], there was an incident in which there was a fire — I think it was related to tire burning — in very close proximity to one of the apartments that one of the caregivers and her family were living in. These things happen commonly. So, from the perspective of the caregivers, there are multiple different factors that contribute to their children's poor respiratory health.

SP: Can you take me through a day in the life of one of these caregivers, based on the evidence you gathered?

AC: It could be a beautiful day. The caregiver walks outside. It's sunny; everything's beautiful. In my opinion, this environment is very beautiful. Maybe, later on in the day, there is a pickup of wind, and there's dust. Let's say the caregiver is a mother with a child who has asthma who's at school. The children are outside on the playground. Her child is going to be highly affected by the dust that's being picked up by the wind. What's going to happen is, the school will bring the child inside, and if the child doesn't have too severe of a respiratory distress, the child could stay at school. Otherwise, the caregiver will get called and have to come to school and pick up their child.

Most folks in that region are farm laborers. They're not owners of farms; they are the ones who are working the land for the owners. Many individuals who are living in very impoverished conditions — for instance, the Purépecha community, which is the Indigenous community we worked with that's from Michoacán in Mexico — are pickers. They are in the lowest-social-ranking jobs within farm labor, and, in part, that's because they may be monolingual Purépecha. That means they don't speak Spanish or English, and that limits the type of employment they can have.

In a situation where you have this very precarious employment, if your child needs to be taken out of school and you are the caregiver, then you risk losing your job. That's the type of dynamic that's at play among many of the families that we work with.

SP: What are the long-term consequences of living day after day in these conditions?

AC: It's a really poor quality of life for children, especially. There's a picture that a caregiver took of her child that I think exemplifies so well the experience of children and their quality of life. The child is just lying on the floor in their home. The photo illustrates the child's lethargy and the boredom and the fact that caregivers often choose to have their children stay inside, because they can better control the indoor air quality. They can't necessarily control what's going to happen outside, but they can control indoor air quality.

The problem is, if the family doesn't have the resources to have an air filter to clean and purify the air, for instance, then what we've noticed in our research is that there can still be very poor indoor air quality, particularly when there's more extreme weather events like fires or dust storms.

With the research, I anticipated very poor quality of life for children. But what I understood less was that it also means poor quality of life for their families, and particularly for mothers, who are often the primary caregivers. It really affects their mental health and well-being.

SP: Currently, are there any measures in place to protect these families?

AC: There has been Assembly Bill 617, which was a measure to engage members of the communities that are most affected by the Salton Sea environment in a process of mitigating the effects of the sea. From that, there have been a lot of community meetings. Years ago, I started to participate as one of the advisory board members. It became a bit frustrating — and I think this illustrates the history of frustration in this region — because government entities come in with resources and money. But it's very top-down, and often the community gets upset and frustrated because they don't see these agencies making changes in the community. There's a lot of talk and very little action.

There are also monies that have been dedicated to Salton Sea restoration, and there's been an ongoing conversation about a 10-year plan to mitigate the effects of the drying of the sea. But the focus has been primarily on wildlife, not human health. Only more recently have there been conversations about human health and the public health implications.

For individuals who have a specific diagnosis of asthma, they may qualify for retrofitting. That means they will receive money through their health insurance to be able to invest in improving their home. That might mean taking out carpet [which can capture dust], or maybe fortifying windows or doors ‪—‬ things like that. But it's a really small amount of money. It can help to a certain degree, but I think in this community, in particular, they may not always know how to navigate the healthcare system to get access to that type of resource. In addition, the most vulnerable people in this community don't have access to health insurance.

SP: What more could be done to improve people's quality of life in this community?

AC: We installed air-quality monitors in people's homes, and we spent a lot of time collaborating with communities in this region. Some live in apartment complexes; some live in single-family homes. But the majority live in mobile home parks, in which they're living in very old, dilapidated trailers. The land is dirt. It's an area that is very impoverished.

So, when I think about these communities, in particular, they can't protect themselves from the external environment. In terms of policies, [I wonder] how we can put money toward building housing that is not trailers and can really protect people from the dust. Right now, the wind is bringing dust into the homes. We need to find ways to actually keep the homes sealed.

SP: The Salton Sea is a hotspot for lithium, and although there are currently no active lithium mines in the region, policymakers and private companies are investigating the sea's potential to host one. How might lithium mining affect the families you worked with?

AC: That conversation's been going on for several years now. At the moment, it's not as much a community concern, because there's been very little movement [to open mines]. There was a lot of action and movement about three or four years ago. But it's been a few years since they've been testing the prototype, and it doesn't seem like it's gone to scale, where they would have been able to commercialize it.

Initially, the community was quite upset, because it's just another example of the lands being exploited and other people benefiting. Typically, the beneficiaries are individuals who are not originally from the community and who have professional degrees. They get the resources, and they get to make decisions about the resources. Then, the conversation was, "Well, but if we have this type of business coming in, then it can create jobs." But we know that it creates jobs for individuals who have professional degrees, or they'll have to get some type of training; they're not jobs for farmworkers or individuals who are undocumented.

It takes a lot of water to do lithium mining, so that also has implications for the continuation of the shrinking of the Salton Sea.

SP: Other lakes around the U.S., including Utah's Great Salt Lake, are shrinking and exposing toxic sediments that are then blown into residential areas. Do those drying lakes have similar effects on local communities?

AC: There is a film director [Abby Ellis from around the Great Salt Lake] who, I think two years ago, came to the Eastern Coachella Valley and met with myself and my team members. She said, "I want to get a sense of what's going on here, because this is essentially where we are going to be 10 or 15 years from now."

I had the opportunity to very briefly chat with her, but also view the trailer for her documentary. One of the distinctions between the communities surrounding the Great Salt Lake and the Salton Sea is the color of the skin of those living around these bodies of water. In Utah, it seems to be more so individuals who maybe are middle class, or have a certain access to resources — people who can have a political voice and organize and say, "We don't want this to happen." It will be interesting to see if there can be more change in communities where there are more affluent people living near these bodies of water.

This interview has been condensed and edited lightly for clarity.

Growing water scarcity could hamper the expansion of lithium mining in the U.S., deepening its reliance on foreign imports over the coming decades, a new study finds.

Lithium is used in electric-vehicle and energy-storage batteries due to its high energy density and low weight compared with other minerals, but mining it requires a huge amount of water. Currently, the U.S. has only one active lithium mine, in Nevada, and with demand for the metal projected to explode over the next few years, the government and private companies are planning to open at least 115 new mines across the country, according to the study.

However, most of the proposed mines that are in advanced stages of development overlap with water-stressed areas, specifically in the western U.S. In the new study, published May 28 in the journal Communications Earth & Environment, scientists found that if lithium mines start operating in these regions, they will compete for water not only with households, agriculture and industry, but also with one another and with other proposed mineral mines.

"Future water availability under climate change may constrain whether new lithium mines will have sufficient water to operate," study senior author Jennifer Dunn, a professor of chemical and biological engineering and the director of the Center for Engineering Sustainability and Resilience at Northwestern University in Illinois, told Live Science in an email.

The U.S. imports more than 50% of its lithium, mostly from Chile and Argentina. Policymakers and corporations want to reduce this dependence, but even with the existing Nevada mine and the 22 proposed mines that are the closest to coming online, the U.S. won't have enough lithium to meet domestic demand, Dunn said.

"Every mine produces a different amount of lithium — depending on its deposit type, lithium grade, and final product — so we are unable to determine how many mines exactly would be needed," she said. "Our analysis estimated that if all 22 advanced [stage] proposed mines and the sole operating mine continued operation into 2050, 0.14 [to] 0.25 million metric tons [0.15 to 0.28 million tons] of lithium content in products could be produced per year."

This range falls short of the 0.83 million to 1.9 million tons (0.75 million to 1.7 million metric tons) of lithium per year that other researchers previously estimated the U.S. would need to cover its own demand.

However, the water demand to produce more lithium would be astronomical. That's because lithium is typically extracted from brines and rocks known as pegmatites, which require large-scale evaporation and aggressive processing with fresh water, respectively.

To find out if the U.S. would have enough water to support additional lithium mines under intensifying climate change, the researchers calculated the future water use of the 23 lithium mines most likely to be active in 2050, using data from mining companies. Then, they layered this projected water use on top of projected water uses from other sectors, such as agriculture and manufacturing, under four modeled socioeconomic-climate scenarios between 2040 and 2060.

The researchers found that the available water supply will, in most cases, be insufficient to support new lithium mines. The starkest example was Southern California's Salton Sea, which contains roughly 4.5 million tons (4.1 million metric tons) of lithium. The Salton Sea is fed by the Colorado River and showed the least water available to support lithium mining and other water demands, owing to the river's dwindling flow.

Lithium deposits in the U.S. are clustered in Nevada, Arizona and California. These are also some of the most arid and water-stressed states. Although the study found an increase in rainfall under a high emissions, "business as usual" climate scenario, these regions likely won't have enough water to support other activities, let alone additional lithium mining, Dunn said.

There were four exceptions in the study, including lithium-rich sites in North Carolina and Arkansas, which may have enough water to support future mines. However, there are other concerns related to lithium mining.

"Many of the lithium deposits in the United States reside near federally-recognized Indigenous and Tribal reservations, and the mines could violate Indigenous rights," Dunn said. "Lithium mining could also disturb sensitive ecosystems and biodiversity. And, like many other mineral mines, pollution, soil erosion, and water contamination are concerns."

Together, the findings highlight a catch-22 in the quest to source lithium: Lithium is essential to support a green energy transition and curb climate change, but shrinking water availability due to global warming is making it harder to extract lithium.

The study did not explore potential improvements to water-use efficiency that could reduce the pressure on some water resources and increase the availability for activities such as lithium mining. Nor did the researchers include water exchanges known as interbasin transfers (IBTs) in their analysis, due to the lack of studies about these transfers under climate change.

"IBTs could help supply water to arid or water-stressed regions," Dunn said.

Still, there is likely an upper limit on how much water can be allocated to lithium mining in a warming world, according to the study. This means the U.S. will probably continue to partially rely on foreign supply chains for lithium and other critical minerals.

For years, scientists have suspected that, at the molecular level, water is two different liquids ‪—‬ a denser one and a less-dense one ‪—‬ that are constantly switching places. Catching real molecular evidence of this microscopic transformation has been hard. But now, with help from artificial intelligence, researchers say they've finally found it.

"It's hard to imagine — here is just one water, right?" said Xiao Cheng Zeng, a physical chemist at the City University of Hong Kong and co-author of the new study, told Live Science while holding a water bottle in the air. That puzzle sent him digging through scientific literature, where he found the possible explanation: the two-state hypothesis. "That got my attention. We have literature to talk about it but no evidence."

The findings, published June 4 in the journal Nature Physics, could not only prove this long-sought molecular change is real, but also help to explain dozens of water's weird behaviors.

Most liquids become denser as they cool, but water behaves differently; it becomes denser until about 4 degrees Celsius, then starts to expand, which is why ice floats. Water also resists temperature changes better than similar liquids and has a viscosity that decreases under certain pressures. Scientists have documented various anomalies related to water and suspect they may be interconnected.

The two-state model is an attempt to be that unifying explanation.

A 30-year hunch

Zeng has been studying water since his postdoc days in the late 1990s, when he worked on liquid freezing. The two-state hypothesis itself came onto his radar later — around 2006, when he first encountered it at scientific conferences. But for years, he set it aside as too difficult to tackle directly. That changed roughly around 2016, as researchers began reporting experimental evidence that supercooled water could split into distinct high-density and low-density forms.

Around two and a half years ago, Zeng handed the problem to Liwen Li, a postdoctoral researcher in his lab. Rather than repeating the conventional approaches other groups had already struggled with, Li suggested the use of "unsupervised deep learning" — AI trained to spot patterns in data without being told what to look for.

"So AI [is] forced to learn — to use [its] knowledge to create, to explore," Zeng told Live Science.

The team ran massive molecular dynamics simulations, using the GROMACS simulation package. They tracked how hundreds of thousands of water molecules moved and interacted and generated tens of millions of data points.

"Traditionally, you may need a lot of students to figure that out. ... With computers and AI, it took [Li] maybe a year and a half," Zeng said. Without AI, he estimated, the same analysis might have taken closer to a decade.

The AI came back with "reaction coordinates" — a small number of variables, distilled out of all that molecular motion, that describe exactly how a water molecule's local arrangement shifts from the denser structure to the looser one and back. They plotted the system's behavior along those coordinates to see the shape of the conversion. That included the number and location of energy barriers, or saddle points, that molecules have to cross to make the switch.

Two paths up the mountain

The team found that the path the two structures take to convert into each other changes depending on certain conditions. Most of the time, the switch happens along what the researchers call a "semi-loop" pathway, with a single energy barrier to cross.

But near the boundary between high-density and low-density water — the same kind of threshold where ice and liquid water coexist at 32 degrees Fahrenheit (zero degrees Celsius) — the molecules can take a more roundabout "full-loop" path, with three separate barriers instead of one.

Zeng compared it to hiking a mountain that's been sliced in half, with a gentle slope on one side and a sheer cliff on the other. Most hikers stick to the slope; that's the semi-loop. But near the boundary where the two halves meet, it's as if the mountain were becoming whole again, letting hikers circle the entire peak. That's the full loop.

Zeng and his team are now building a more rigorous machine-learning model to confirm the result. They hope to eventually connect it to properties like density, viscosity and temperature.

Confirming the structure in real water won't be simple. Zeng said it will likely require new and sensitive experimental techniques — the kind developed by labs like Pacific Northwest National Laboratory, which previously found indirect spectroscopic evidence for water's two-state behavior.

"Once we have this ... confirmed by experiment," he said, "this model can be used to [understand] how water interacts with nature."

Since most biological and pharmaceutical processes happen in water, a better understanding of water's molecular structure could shed light on how dissolved salts, proteins, and drug molecules interact in solution. "These interactions are vital for injectable drugs and cell function," he noted, but applying this knowledge to practical uses is still a long way off.

Energy used to power artificial intelligence (AI) could jump to 3% of global electricity demand by 2030, guzzling as much water as the 1.3 billion people in sub-Saharan Africa consume in one year to meet their domestic water needs.

Those are the conclusions of a recent United Nations report that estimated the land use, water consumption and greenhouse gas emissions associated with AI's breakneck expansion. If the data centers that underpin AI formed a country, they would rank 11th in the world for energy use due to their high infrastructure and electricity needs to train ever more complicated models and satisfy users, the report found.

By 2030, data centers could rise to sixth in the world for energy consumption, which would have a land footprint the size of Connecticut and release emissions comparable to those of the U.K. in 2025, depending on how much renewable energy is in the mix.

The findings highlight how much additional pressure AI and the infrastructure that supports it could put on the environment and the climate within the next few years. But why does AI have such a huge footprint, who is benefiting or being left out from the opportunities linked to AI's growth, and what can be done to limit the damage?

To find out more, we spoke with Kaveh Madani, lead investigator for the U.N. report; director of the United Nations University Institute for Water, Environment and Health; and the recipient of this year's Stockholm Water Prize.

Sascha Pare: What would you say is the main takeaway from the report?

Kaveh Madani: The main takeaway of this report is that although in the general discourse AI is perceived as something virtual, or digital, or up in the clouds, there is [a] massive physicality to AI and the supply chains and infrastructure that back it up. And that's one thing that this report has tried to do: to remind people that behind every prompt, every use, every interaction, there is some level of impact on the environment. This is because from the top of the supply chain, where the extraction of critical minerals happens, to the point of manufacturing the hardware, the construction of the data centers, then the operation of data centers, and then dealing with the e-waste, there are major environmental impacts. If we take all of those into account, then we realize that what's digital is not necessarily free of impact. There is always some footprint associated with it, and we have to remember that.

SP: Why does AI have such massive land and water footprints, specifically?

KM: The report outlines the carbon, water and land footprints of AI's energy use. All along the supply chain, from the extraction of critical minerals to the point of disposing and dealing with the electronic waste, we have actions and interventions that require water, require land, and are associated with carbon emissions. So, if you think about, for example, the extraction of critical minerals, we know that during the process, a lot of water is being used and a lot of water is being polluted and poisoned. We published a report in April about the water injustice implications of the critical minerals, showing exactly what is happening where we have the extraction of critical minerals.

But let's not forget that the [new] report is focused on AI's energy use, and then tries to argue that the energy production process itself requires also a lot of water and land. If you are using hydropower to provide energy to your data center, you're using a lot of land and a lot of water. This applies to all sorts of energy sources, regardless of being clean or not, or if you consider them renewable or not — they all require water and land. On top of this, of course, you need to build data centers on land, but also you need water for cooling. That's why, throughout the supply chain, throughout the life cycle of AI, we have a lot of water and land use, in addition to carbon emissions.

SP: The report is packed with jaw-dropping statistics about how big AI's environmental footprint could get by 2030. But how significant are the impacts?

KM: First of all, it is very hard to estimate exactly how much energy AI is currently using, but we know that roughly 20% of the current load of data centers can be attributed to AI. We are expecting that to be 40% within a few years. And by then, the data centers that back AI's operations are expected to have an energy demand that is about 3% of the total energy demand of the world. This is equivalent to being the sixth-most-energy-intensive country in the world. The water demand of that is also huge; the water footprint associated with that is enough to satisfy the domestic water needs of 1.3 billion people in sub-Saharan Africa.

SP: Can the environment and communities cope with the projected levels of energy and water consumption needed for AI?

KM: There would be places in the world where big decisions must be made, meaning that you have to decide if you want to continue using your water for agriculture or if you want to put it into data centers. Those would be decisions for the communities — and if the communities are not involved, then the most vulnerable, the poor, will be dealing with the consequences.

At the same time, we know that the world's electricity consumption keeps increasing. That's a major problem, because although we are trying to add more and more renewables to the energy supply systems, the renewables cannot keep up with the increasing electricity demand. This means that not only can we not retire the old systems, but we might also need to use more fossil energy to satisfy this growing demand. And of course, that means more pressure on the fragile environment.

We know some of the data centers are being placed in locations that are already dry or suffering from what we refer to as "water bankruptcy," based on the report we published in January. These are major issues. More pressure on the environment [puts] more pressure on humans, and this recipe means [we could have] a kind of reinforcing degradation loop that would jeopardize both nature and human society.

SP: Who is benefiting the most from AI's expansion, and who is being excluded?

KM: AI expansion is benefiting humanity as a whole. It has changed our lifestyle; it has provided a lot of opportunities and improvements. But at the same time, it has some consequences. The issue that we see right now is that the richer communities and countries of the world are the ones that are benefiting from it the most, and within those communities and countries, it's the rich who are also profiting more from the expansion. If you look at the investment landscape of AI, you can see that there is a lot of push from a number of strong players and private investors. And they don't bear the costs when it comes to pollution, water bankruptcy, land degradation and so on.

If you think about the emissions, they are contributing to global warming, and everybody would suffer from it. Even the countries that don't have AI infrastructure are affected: If you think about where the critical minerals come from, you see a lot of poor communities, poor countries and poor regions in Africa, South America, parts of Asia, where people don't have basic infrastructure — they don't even have clean drinking water and energy infrastructure. They don't benefit from this expansion and the profits and utilities it provides. It's the most vulnerable communities and the poor economies that are going to suffer the consequences, while the other ones will benefit more.

SP: How did you estimate AI's growth by 2030, and how likely is it that your numbers will come true, given the fears that AI is a bubble that's about to catastrophically burst?

KM: We were looking at the data centers, and we still think that our projections are conservative. There is a lot of push from the private sector to further growth. Countries are also seeing investment in AI and data centers as an investment in security, sovereignty and other matters, so there's also a competition there. Some of the investments — some of the decisions about expanding AI — are not necessarily based on comprehensive assessments. Investments remain a bid to stay in the race, and that means more and more push. So we think that what we have projected is probably very conservative.

SP: China is scaling up its energy capacity together with data center buildout, and it is putting data centers in the ocean to try to solve the hardware cooling issue. What do you make of this strategy, and should other countries learn from it?

KM: China's more centralized decision-making system provides advantages, but I think we need to be careful about generalizing the information of one or two projects highlighted by the media to the overall strategy.

We know that China has been expanding its renewable energy production capacity, and that's definitely a good thing. We have to make sure that the additional load of AI would not mean more fossil energy and would not compromise the decarbonization process. But at the same time, we should note that just scaling up renewables is not sufficient if you're thinking about decarbonization. We need a massive addition of renewables if we're going to reverse climate change, and we are not seeing strong enough signs of that around the world. So that's something that we have to be worried about.

That has been the challenge created for the world because of the expansion of AI. When it comes to putting things under the ocean, I think we do not yet have enough information and enough experience to judge if those things come with less environmental impact. What we hide would not be impact-free; there are also other impacts to worry about.

SP: What are some other solutions to the pressures AI is putting on the environment and people? How should we approach the rapid expansion to ensure it is fair?

KM: We offer a framework based on a number of principles about making the AI governance system more fair and transparent and sustainable. So, those are the principles suggested, and they bring responsibility to all stakeholders, including the developers and service providers — those who provide the technology and have responsibilities of ensuring that their systems are more transparent and efficient.

Then, we have the governments that have the responsibility of ensuring that information becomes available, that footprints are properly monitored and disclosed and regulated. They can use a range of incentives, mechanisms or penalties to ensure that footprints are reduced across the supply chain — and I insist on that — from the mines to the landfill. So, that can be done; pollution taxes can be charged and so on. [Governments should ensure] that those who have to deal with the consequences also benefit from the profits and the opportunities that data centers bring to their communities. Decisions must be made based on resource availability and the environmental consequences taken into account.

Users also can do a better job of making smarter choices by using AI more responsibly and only when it's absolutely necessary. When using AI, choose the right models, and be mindful of what is happening behind the scenes. Is it really necessary to generate another image? Is it really necessary to generate a video? Is it necessary to use the model in the "thinking mode"? Together, all the stakeholders can make a difference, and users can also call for more transparency and force governments to take action to force the service providers to provide more information and be more transparent.

Editor's note: This interview has been condensed and lightly edited for clarity.

As water molecules move around the planet through the water cycle, they take on many forms, moving from solid to liquid to gas and back again. They can make up snowpacks melting in the spring, a river rushing to the ocean, clouds carried on sea breezes, and even pee flushed down the toilet.

But with this complex cycle of evaporation, condensation and precipitation continuing over and over, has the water coming out of your faucet been inside a dinosaur or a mammoth at some point? And does that mean all the water on Earth has been peed before?

The answer depends on how you approach the question.

For Neil Donahue, director of the Steinbrenner Institute for Environmental Education and Research and a professor of chemistry and chemical engineering at Carnegie Mellon University, the answer is likely yes, based on a back-of-the-envelope calculation. But this math is based on a few assumptions, Donahue told Live Science over email.

The first is that the average person weighs about 110 pounds (50 kilograms) and pees about 0.26 gallons (1 liter) per day, which is roughly equivalent to 2.2 pounds (1 kg). Then, Donahue made a "WILD assumption" that all animals pee roughly the same proportion — 1% of their body weight — which he said is "probably wrong" but helpful for a ballpark estimate.

Next, if the total mass of all chordates (the taxonomic group that includes mammals, birds, fish,) is approximately 2.2 billion tons of water and carbon (2 billion metric tons), this equates to around 0.02 gigatonnes — or 8,000 Olympic-sized swimming pools — of pee every day, Donahue said. For the sake of the calculation, he assumed that the weight of chordates has remained constant over time.

On the water side of the equation, the U.S. Geological Survey estimates that Earth has about 1.4 billion gigatons of water, including that in oceans, ice caps, glaciers, lakes, rivers, groundwater and vapor.

If you divide the weight of the world's water by 0.02 gigatonnes of pee each day, it would take around 70 billion days, or about 191 million years, "to pee out the whole ocean," Donahue said. Given that chordates emerged at least 500 million years ago, this is "plenty of time" for all water to become pee at one time or another, he said.

David Kreamer, a professor of hydrology at the University of Nevada, Las Vegas, agreed that when "you go back in history to the dinosaurs and things like that, that's a lot of pee." But he also said calculations that depend on assumptions and generalizations have a large margin of error.

Instead, when it comes to whether every last drop of water on Earth has been peed at one time or another, Kreamer said the answer is no.

For one, water does not move through the water cycle at a constant speed, he noted; water can be trapped as glacial ice for hundreds of thousands of years, and "there is some deep groundwater that's been underground for tens of thousands of years."

What's more, some water hasn't ever been in the water cycle, he said. This water, known as juvenile water, is trapped deep below the planet's surface and "hasn't really emerged from the depths of the Earth ever in Earth's history," Kreamer told Live Science.

Over time, juvenile water can be brought to the surface through volcanic activity in the form of steam or lava. Trapped deep in Earth's crust, "it's released when magma dissolves it, and when a volcano blows up into the atmosphere," Kreamer explained, noting that during eruptions, "there's a certain amount of water or moisture that's released" alongside ash and rock. This water would then enter the water cycle and could eventually find its way into and out of an animal.

Ultimately, at any given time, at sites of volcanic activity around the world, there are streams of new water reaching the surface for the first time. That water "hasn't been peed," Kreamer said ‪—‬ at least, not yet.

Editor's note: This article was updated at 1:41 p.m. EDT on June 15 to fix a math error: 1% of 2.2 billion tons is around 0.02 gigatonnes (8,000 Olympic-sized swimming pools) of pee, not 0.2 gigatonnes (80,000 Olympic-sized swimming pools) as was previously stated. This means it would take approximately 191 million years to "pee out the whole ocean," not 19 million as was previously stated.

As a result, researcher Neil Donahue changed his answer from "emphatically yes" to "likely yes." Despite this error, Donahue says that would still have been enough time if you go back to when chordates first emerged. Previously, he had gone back only to the end of the dinosaur age and said that mammals alone could have done it.

Scientists have invented a self-cleaning coating that prevents stains from food, oil or dirt from sticking to a fabric's surface, making the spots easy to remove without detergent or large amounts of water. The coating, which creates a protective ultrathin layer of water its developers call "molecular water armor," could reduce the water and electricity demand of household laundry by over 80%, new research suggests.

Washing clothes is a basic necessity of everyday life, but laundry has a huge environmental footprint because it produces vast amounts of wastewater. A single cycle in a household washing machine uses 10.5 to 16 gallons (40 to 60 liters) of clean water, while the detergents required to remove stains promote the release of microplastics from synthetic fibers and leave chemical residues in the discharged water.

Better detergents and more efficient washing machines are slowly reducing the ecological impact, but with an estimated 2.6 billion gallons (10 billion liters) of wastewater generated annually from laundry in China alone, there's a need for additional measures.

In the new work, reported in the journal Communications Chemistry March 19, researchers tackled this problem from a completely different perspective, focusing on the design of the textiles themselves.

"Instead of relying on detergent to remove strongly attached dirt, we modify the textile surface so that stains do not adhere strongly in the first place," material scientists Chongling Cheng of Southeast University and Dayang Wang of Jilin University in China, both co-authors of the research, told Live Science in a joint email. "As a result, many common stains can be removed using water alone and a much shorter rinsing process."

"Molecular water armor"

The team, based at Southeast and Jilin universities in China, spray-coated alternating layers of positively and negatively charged polymers onto cotton, silk and polyester clothing. The resulting multilayer film formed a surface rich in sulfonate groups — sulfur-containing chemical units — which attracted and organized water molecules into an ultrathin layer on the fabric's surface.

"We sometimes describe this layer as a molecular 'water armour,'" Cheng and Wang said. "[It] acts as a barrier between the fabric and contaminants. Oils, food stains, sweat residues, and microorganisms find it difficult to make direct, strong contact with the coated fiber surface. Therefore, stains are much less strongly attached and can be removed by water flow, without the need for detergent." This contrasts with waterproof materials which simply allow water droplets to roll straight off, rather than producing a cleaning effect.

The researchers demonstrated this superior cleaning performance by pitting the new coating against conventional detergent-based washing to launder cloth soiled with ketchup, chili oil and soy sauce. It proved particularly effective for these oily surface stains, and the coated fabrics cleaned with just a single rinse — matching or outperforming the detergent wash for stain removal.

An analysis of the small amount of wastewater produced by the rinse wash also revealed that this additional layer drastically suppressed the release of microplastics during washing, trapping any stray particles within the coating itself.

Overall, the polymer layer substantially improved the environmental footprint of the laundry process; the team calculated that it reduced the water and electricity demand by more than 82% compared with a normal cycle. From a cost perspective, these stain-resistant fabrics are more expensive to manufacture than standard textiles, but the team noted that this upfront expenditure could be recouped in as few as 15 laundry cycles, depending on the cost of the detergent.

The coating also addresses laundry hygiene. The coated fabrics showed both antibacterial and antifungal effects, which are most likely related to the water armor barrier, Cheng and Wang said. The repellent surface prevents microbes, sweat and skin cells from adhering to the fabric, allowing them to be easily removed by rinsing. As a result, a quick soak completely eliminates odors and prevents the growth of mold or mildew, which can occur during prolonged storage.

But convincing consumers of these clean credentials could prove challenging. "Many people associate detergent foam and fragrance with cleanliness, even though foam and fragrance are not necessarily direct measures of hygiene," Cheng and Wang said. "Therefore, we expect that consumer trust will require clear evidence, transparent testing, and practical demonstration."

The coating is still in the proof-of-concept stage. Preliminary investigations by the team have suggested that it is safe to use against skin and remains effective over more than 100 laundry cycles. Given the coating's nanoscale thickness, the team doesn't expect it to change the texture or breathability of treated clothing. However, a crucial next step will be to have consumers test the materials to validate their comfort and practicality in real-world settings.

"Commercialization will also require independent safety assessment, durability standards, [and] environmental lifecycle analysis," Cheng and Wang said. "Our current study demonstrates the central scientific principle. The next challenge is to translate this principle into a robust, affordable, and trusted product for everyday use."

Mangrove forests around the world provide a largely overlooked nitrogen-pollution cleanup service — one that, if humans had to pay for it, would cost $8.7 billion per year, a new study estimates.

Mangroves are salt-tolerant plants that grow between the high-tide and low-tide marks in tropical and subtropical coastal regions. Their tall, tangled roots trap sediments rich in microbes that break down nitrogen in the water into nitrogen gas (N₂) and nitrous oxide (N₂O), effectively removing this nutrient from the ecosystem.

Researchers were aware that mangrove forests are valuable carbon sinks and provide a host of other ecosystem services, including coastal defense against storm surges and a buffer against erosion. But these forests' ability to remove nitrogen is poorly understood, despite the havoc that nitrogen pollution is known to wreak in aquatic ecosystems, the authors of the new study told Live Science.

"We're still really in the infancy of trying to understand what is driving this nitrogen removal," Benoit Thibodeau, an assistant professor in the Department of Earth and Environmental Science at The Chinese University of Hong Kong, said in a joint interview with his co-author Ziyan Wang, a doctoral student in environmental science at the same university. "You're taking reactive nitrogen … and you're removing it to the atmosphere as N₂, which is nonreactive and has a residence time of thousands of years."

Nitrogen pollution is caused by excess nutrient runoff into water systems due to human activities such as agriculture. Between 2002 and 2010, this runoff amounted to 35.9 million tons (32.6 million metric tons) of nitrogen per year in freshwater ecosystems. This pollution promotes algal growth, leading to blooms that massively reduce oxygen availability for other species and release toxins into the water that can make animals and people sick.

Mangroves forests cover less than 0.1% of Earth's land surface, but they remove about 960,000 tons (870,000 metric tons) of nitrogen from water systems each year, the new study found. That's roughly equivalent to the mass of 650 giant sequoia (Sequoiadendron giganteum) trees — but optimal conditions for mangroves could boost their removal capacity to more than 5.5 million tons (5 million metric tons) per year, which is equivalent to the weight of over 4,000 giant sequoias. The findings were published April 29 in the journal Earth's Future.

Thibodeau and Wang analyzed the results of 51 previous studies, as well as measurements they took themselves, to estimate global nitrogen-removal rates in mangrove forests. They divided the data into actual removal rates, which are those observed in nature, and potential removal rates, which capture the amount of nitrogen that mangrove forests could soak up if temperature, salinity and nitrogen levels were optimal.

Then, the researchers calculated averages for the actual and potential rates — and these, together with a global mangrove area estimate of 52,459 square miles (135,869 square kilometers), yielded an actual removal rate of 960,000 tons per year and a potential removal rate of over 5.5 million tons per year.

Microbes in mangrove forests remove nitrogen via two main pathways: denitrification and anaerobic ammonium oxidation (anammox). Denitrification transforms nitrate in the water into nitrogen gas and nitrous oxide, which is a greenhouse gas. Anammox, on the other hand, converts nitrite and ammonium into nitrogen gas, which makes up 78% of the atmosphere and is not a greenhouse gas. These pathways work best with relatively high nitrogen concentrations, but there is a threshold past which removal slows, according to the study.

These pathways also occur in seagrass meadows and other coastal environments, but mangrove forests are especially good at removing nitrogen because their sediments are oxygen-poor, which promotes the right kind of microbial activity, Wang said.

Similar to carbon credits that people can purchase to offset their emissions from activities like flying, the researchers used a market-based credit approach to calculate the economic value of nitrogen removal in mangrove forests. Based on what municipalities in countries like Australia and the U.S. pay to get rid of nitrogen in their water systems, Thibodeau and Wang settled on a price of just over $10,000 for every metric ton of nitrogen removed anywhere in the world.

"Carbon has a very mature credit market now, but for nitrogen, it's not that mature," Wang said. "We did a very early investigation about how different markets, or different industries, deal with this kind of nitrogen pollution."

At the current rate of nitrogen removal, mangroves' cleanup service is worth $8.7 billion per year globally. If removal rose to 5.5 million tons per year, it would be worth around $57 billion annually, according to the study.

The researchers also calculated the economic value of carbon sequestration in mangrove forests and found it was 12 times smaller than that of nitrogen removal. Notably, carbon sequestration is also less stable than nitrogen removal is, because mangroves store carbon in sediments that can be disturbed. On the flip side, mangrove forests convert nitrogen in the water mostly into nitrogen gas, which stays in the atmosphere, Thibodeau said. Nevertheless, mangrove forests "have a very high rate of storage of carbon compared to other ecosystems," he added.

Mangroves are mostly threatened by sea-level rise and land clearance for infrastructure, Thibodeau said. The results highlight that "we're not only losing space or nature, but we're also losing a very important financial value."

Mangroves have a relatively high heat tolerance, but rising global temperatures could alter how the microbes they host consume nitrogen, Wang said. Specifically, these microbes may start to rely more on denitrification, which could release more of the greenhouse gas N₂O than at present.

Catastrophic water shortages are in store for the 40 million people living in areas fed by the Colorado River, even if cities in the region such as Denver, Phoenix and Las Vegas make dramatic cuts to their usage, recent research suggests.

Water shortages could start as soon as this summer, as snowpack levels reached a record low over Lake Powell and the spring runoff into the Colorado River is expected to be minimal, experts told Live Science. And the region's major cities, which have already slashed their per capita water consumption by up to 58% between 2002 and 2025, can't solve the problem alone.

"We can't just shove it all onto the residents of these cities and tell them to use less water, because it's still not going to be enough [to prevent water shortages]," Renee Obringer, an assistant professor in the Department of Energy and Mineral Engineering at Penn State and the first author of the new study, told Live Science. "Regardless of what mitigation we do, we're still going to have to adapt to this warmer world that is going to have more intense droughts and more frequent droughts."

The findings reveal that bolder measures will be needed to head off disaster in the Colorado River basin. But exactly what are those steps?

One piece of the puzzle

Seven states — Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming — pull water from the Colorado River, and the amount allocated to each region is governed by a century-old document called the Colorado River Compact.

But the Colorado River basin, along with the rest of the U.S. Southwest, has been in a megadrought for 25 years. Between 2000 and 2019, the river's flows shrank by 20% due to climate change and water overuse to supply cities, agriculture and industry.

Finding new water supplies is unlikely, so Obringer and her colleagues analyzed what would happen if three large cities fed by the river — Denver, Las Vegas and Phoenix — reduced their consumption by around 25% under various climate scenarios, ranging from a global temperature increase of about 2.9 degrees Fahrenheit (1.6 degrees Celsius) to an increase of 7.7 F (4.3 C) compared with preindustrial levels.

Their results were published in December 2025 in the journal Water Resources Research. In most climate scenarios, demand management — which encompasses broad strategies such as raising awareness, offering rebates, and subsidizing low-flow devices — did not make up for lower water storage in urban reservoirs caused by higher temperatures and lower precipitation in the region. Denver, which is technically not located in the Colorado River basin but gets half of its water from the Colorado River, was the lone exception. Demand management compensated for river flow reductions in two high-emissions climate scenarios for the city. However, Obringer suspects some of those more optimistic results could be an artifact of the way the model handles uncertainties.

Cities fed by the Colorado River basin have reduced water use through programs aimed both at demand and reuse. In Las Vegas, for example, residents receive cash rebates for replacing water-heavy lawns with desert plants. The city, which gets 90% of its water from the Colorado River, also returns, after treatment, 40% of the water it uses to Lake Mead, where it can then be reused.

Cities have taken significant steps to reduce their footprint, and they will likely continue to improve, said Brad Udall, a senior water and climate research scientist at Colorado State University’s Colorado Water Center who was not involved in the study. As a result, some of the region's biggest cities use less water per capita than they did a few decades ago.

But the more efficient cities get, the fewer opportunities they will have to save and reuse water, Udall told Live Science.

Bigger water users

The results highlight a reality scientists have long known: Demand management alone cannot offset the Colorado River's dwindling flows, said Sharon Megdal, a professor and director of the Water Resources Research Center at the University of Arizona, who was not involved in the study.

Cities make up only 18% of water use in the region, while agriculture guzzles more than 70% of the basin's water. "Agriculture's the big user," Megdal told Live Science.

"You can't solve this problem without dealing with agriculture in a major way," Udall agreed. "Because agriculture is 70% of the problem, it needs to be at least 70% of the solution."

Individual farmers have senior water rights to Colorado River water, meaning they receive their full allocation regardless of whether there is a shortage, but political pressure is rising to allocate more water to cities and cut farmers' consumption, Udall said. For example, water managers may decide that farmers in Arizona have to relinquish water to supply the Central Arizona Project canal, which delivers water from the Colorado River to the central and southern parts of the state, including Phoenix and Tucson.

Since 2019, the Colorado River has shrunk so much that it is now 35% smaller than it was on average in the 20th century. "We've never seen flows like this," Udall said. "If these flows continue to drop, I do see agriculture in the Lower Basin not getting the supplies they do [now] and those supplies being reallocated to cities."

The problem is that farmers in the Lower Basin grow crops that benefit the region economically through exports, including alfalfa, cotton, vegetables and citrus fruit. In Arizona, roughly 20% of cropland is used to grow alfalfa for cattle feed. The state is also the biggest cotton producer in the Colorado River basin, and it grows up to 90% of leafy greens consumed in the U.S. and Canada.

To cut their water consumption, farmers can change their irrigation techniques and crop patterns, Megdal said. Drip irrigation, which delivers water directly to the roots, cuts evaporation and reduces water use by up to 50% compared with methods such as flood irrigation used for cotton and alfalfa. Thirsty crops such as alfalfa could be replaced with low-water forage mixes consisting of wheat, barley, oats, rye and peas. Recently, there has also been a focus on guayule, which is a substitute for rubber, as an alternative crop for farmers, Megdal said.

But farmers respond to demand and may have long-term contracts with buyers. "It has to be economical," Megdal said.

Agriculture should switch to more efficient irrigation, but it's also important to realize that some seemingly wasteful methods, such as furrow or flood irrigation, can replenish aquifers, which are also being depleted, Udall said.

Some farmers are letting their fields go fallow, which could happen more and more as water shortages intensify, Megdal added.

Renegotiating water rights

The Colorado River Compact is up for renewal this year, meaning there is an opportunity to devise a more sustainable agreement, Obringer said. But negotiations have stalled between the Upper Basin, which includes Colorado, New Mexico, Utah and Wyoming; and the Lower Basin, which encompasses Arizona, Nevada and California. While officials wrangle over the precise wording in the document, the underlying problem is that the Lower Basin needs more water than it's getting, even though the Upper Basin already uses less water than it was allocated in the compact.

Officials in the Upper Basin have argued that cuts should now fall exclusively upon the Lower Basin. But that can't happen, Udall said, because cuts need to be deep across the Colorado River basin to make a difference. No matter what the Upper Basin thinks it is entitled to, it must accept reductions in water use, he said.

Reality check

Solutions must be found and implemented immediately, because the Colorado River's future has never looked bleaker.

Winter brought barely any snow, and the little that fell melted in early March instead of April, meaning river flows this spring and summer could hit record lows. "It's unprecedented; it's human-caused; it's scary, frightening, awful," Udall said.

Udall estimates that Lake Mead, which serves almost 25 million people in cities such as Las Vegas and Los Angeles, and Lake Powell, which supplies Lake Mead and Indigenous tribes, will be only about 20% full over the coming months. Without adjustments in reservoir release, water levels could drop low enough to prevent energy production at Glen Canyon Dam, which usually produces enough electricity to power over 350,000 homes.

"We're close to dead pool," Udall said. This is when the water level in a reservoir falls so low that it can't flow downstream. "That's never happened, and it's very serious."

It would take years of unusually high precipitation and runoff to recover from the current state, according to Megdal. "It is a challenging situation," she said. "You really have to adjust to a new normal."

To make matters worse, "data centers are popping up everywhere in this region," Obringer said. A midsize data center uses up to 300,000 gallons (1.4 million liters) of water per day for cooling, and this number will only increase as temperatures rise. Much of the water that runs through the system can be reused, but some is consumed to generate the electricity to power data centers.

Some small steps to mitigate the problem are already in the works. Some municipalities are buying water rights and groundwater from rural areas in the region, Megdal said. For instance, the rapidly-growing town of Queen's Creek, Arizona, is purchasing groundwater from farmers and investors in the sparsely populated Harquahala valley. Arizona is also drawing up agreements with California and Mexico to obtain desalinated water.

"I do think there's a tremendous capacity to adapt," Megdal said.

But a more durable solution will require a major overhaul of the existing agreements and water rights to reflect reality, Udall said.

"We've got to have an agreement on how to share the water we have and not pretend we live in the past," he said. "We need to adjust this system to deal with a completely new reality of much less water flow. We've got to balance the books here."

Florida is experiencing its most intense drought in 15 years, with more than 70% of the Sunshine State facing what the U.S. Drought Monitor calls "extreme" to "exceptional" drought conditions.

Northern Florida is suffering the driest conditions in the state, and recent rainfall has brought almost no relief, according to the latest drought data. Forecasts show no rain and high temperatures over the next week, so the situation will likely get worse before it gets better, experts told Live Science.

"Dry conditions have been building throughout the winter," Esther Mullens, an assistant professor of geography at the University of Florida, told Live Science in an email. "Three months ago, 98% of the state was in unusually dry conditions, however only 4% were in severe to exceptional drought. As of currently, this number has risen to over 71% in severe to exceptional drought."

Here's everything you need to know about Florida's drought, including how it got to this point, how long it will last, and what the impacts will be.

Why is Florida in a drought?

Florida, along with Georgia and other parts of the U.S. Southeast, currently sits beneath a ridge of high atmospheric pressure that has moved in and out of the region since fall last year but remained stationary since March. This means the air above the Southeast is sinking and compressing, which reduces humidity and prevents cloud formation.

"Rain cannot form in sinking air so it just stays warm and dry," Pam Knox, an agricultural climatologist at the University of Georgia and the director of the Georgia Weather Network, told Live Science in an email.

Clear skies have dominated for weeks over Florida and other parts of the Southeast. But it's not just high pressure that's driving the current drought, because rainfall has been below average for months. Florida was unusually dry for much of last year, and many areas have received less than 50% of their normal rainfall since Sept. 1, 2025, according to the National Weather Service.

"That means they are about 20 to 25 inches [50 to 65 centimeters] below what would be considered average rainfall," Knox said.

Months of dry weather were followed by a La Niña winter, which shifted the jet stream northward. This brought colder, wetter conditions to the northern U.S. and Canada, while the southern U.S. became warmer and drier.

"The combined effects of the lack of tropical storms last year with the La Nina over the winter, which is usually a time of warmer and drier climate than average, have helped lead to this current situation," Knox said.

Why is the current Florida drought so bad?

The current drought in Florida differs from previous bad droughts because it has hit in spring instead of summer. The last time the U.S. Drought Monitor recorded such exceptionally dry conditions in the Sunshine State was June 2011, but it has not been this dry so early in the year since 2000, Knox said.

While the La Niña, low precipitation, and fewer storms this season are attributable to natural variability, global warming and shifts in the water cycle caused by higher temperatures may be contributing to the dryness, Knox said.

The impact of climate change is difficult to disentangle from natural variation without proper attribution studies, Mullens agreed.

How long will the Florida drought last?

Current drought conditions in Florida will probably worsen until the end of April, but they are expected to improve slightly in May as the high-pressure area in the atmosphere moves away from the Southeast.

"In the Southeast, the worst drought is in northern Florida and southern Georgia, but other areas are likely to get worse over the next couple of weeks with high temperatures and no rain in the forecast," Knox said. "We expect the weather pattern to change around the end of the month as the high pressure shrinks off to the east, which will allow cold fronts that could produce rain to enter the Southeast again."

It's unclear how conditions will evolve through summer, but a lot of moisture will be needed to end the drought. Ideally, a tropical storm or a stationary front should bring enough rain in the coming weeks to quench plants and replenish soil moisture.

"It is difficult to get out of drought in summer because the plants and evaporation tend to use every bit of rain that falls," Knox said.

A strong El Niño is on the horizon, which could bring wetter weather this summer, Mullens said. But a clear picture of this year's drought will emerge only once it's over, when scientists will be able to more accurately compare its length with droughts that struck Florida in 2000 and 2011.

What are the impacts?

Satellite data shows that shallow groundwater aquifers have dried up across the U.S. Southeast during this year's drought. That's because more water has been extracted from these aquifers than usual to irrigate farmland and provide drinking water for people under exceptionally dry conditions.

In Florida, aquifers are especially dry in the northern and central regions. Aquifers do not immediately recover from drought, because rainfall first has to wet the entire soil column before it can trickle down to replenish groundwater stores.

"Aquifers are considered to be a lagging indicator of drought because they get worse after the drought is bad at the surface and it takes them longer to recover," Knox said.

The drought has been felt across Florida, with some water districts imposing restrictions on water use for certain activities such as lawn irrigation. Dry vegetation has also provided ample fuel for wildfires, including a blaze in February in Big Cypress National Preserve, about 25 miles (40 kilometers) east of Naples. And even the Everglades are facing unusually dry conditions, news reports show.

If the drought lasts much longer, there will be more wildfires and possibly even water shortages, Knox said.

It might take several weeks of consistent rain or a tropical storm lasting multiple days to recover from this drought. Ideally, precipitation should be abundant but not come all at once; soils have limits on how much water they can absorb, and the surplus would likely run off, Knox said.

"Florida soils are generally pretty sandy so if it is really dry, they could probably absorb 2 [to] 3 inches [5 to 8 cm] easily over a few hours," she said. "Other areas in the Southeast with more clay soil would not be able to absorb as much."

Farmers, in particular, are desperate for rain. "In all my years of farming, I've never personally experienced a spring this dry," Shannon Nixon, a soybean and peanut farmer near Baker, Florida, told Farm Progress. "To be this dry this early in the spring is very concerning."

The drought may take a huge toll on farmers' income, as many have likely delayed planting crops or decided not to plant crops at all for fear of them dying, Knox said. And if these dry conditions persist, consumers will also be affected, because food production will decrease locally and some of it will not be made up by imports.

"That will mean shortages of some products that are produced locally like vegetables," Knox said.

Humans are depleting Earth's fresh water at a dizzying rate by pumping groundwater and sucking rivers dry. Continents are losing enough water each year to meet the needs of 280 million people. And in January, a report from the United Nations warned that the world is entering an era of "global water bankruptcy," meaning we have irreversibly damaged entire freshwater systems.

Kaveh Madani is the author of this report and the director of the United Nations University Institute for Water, Environment and Health. On March 18, he received the 2026 Stockholm Water Prize, which is often described as the "Nobel Prize of Water," for outstanding contributions to the sustainable use and protection of water resources.

Born in Iran's capital of Tehran in 1981, Madani is the youngest laureate in the prize's history. His parents worked in the water sector, which helped shape his research path and passion for water. Over the past few decades, Madani has worked at universities in Sweden, the U.S. and the U.K., collecting multiple awards for his contributions to the mathematical modeling of complex human-water systems.

In 2017, at the invitation of Iran's government, Madani became deputy vice president of Iran and deputy head of Iran's Department of Environment. But his tenure was brief because the reforms he proposed clashed with entrenched interests. State-aligned media labeled Madani a "water terrorist," and he was arrested and interrogated several times, culminating in his forced exile.

A decade on, Madani is globally recognized for making important improvements to water resources management models. By applying game theory frameworks to human behavior, he has helped show why traditional engineering models often fail to capture real-world complexities.

Live Science spoke with Madani about what water bankruptcy really means, how countries can address water problems, and why artificial intelligence (AI) and data centers are putting additional pressure on globally stretched water resources.

Sascha Pare: Long before the current war, Iran has faced very severe water issues. Were you aware of these challenges growing up? And if so, how did this shape your career?

Kaveh Madani: It's an exaggeration to say that when I was a kid, I knew about the water problems. But certainly, when I was a kid, I knew about water, because I was the only child of parents who worked for the water sector. I read a lot of journals and articles that my parents were bringing home. When I was an undergraduate student, I wrote my first article on Iran's water crisis, so it is true that my passion for water has some real roots. What I saw in my childhood shaped my interest, yet I cannot claim that I planned everything until this point. A lot of things are the product of circumstances.

SP: You coined the term "water bankruptcy." Why is it a useful concept to describe the water situation globally today?

KM: Water bankruptcy, as I have defined it, combines two important conditions. One is insolvency, and the other is irreversibility. Insolvency happens when the use of water resources is much more than the rate of renewal of water resources through natural recharge — when water use is more than what we get from nature deposited into our "account" every year through precipitation.

At the beginning, the environment is very kind to us. It accepts that sort of cut in its access to water. But after a while, nature also starts reacting in a negative way and loses its ability to bounce back. That's when the insolvency is combined with irreversibility, meaning that the system can no longer restore its historical conditions.

What once was an abnormality becomes a new normal. That's when water shortage and scarcity becomes a chronic problem. And that's what we see in many places around the world, where systems face new normals and have lost their ability to bounce back. These systems are no longer in a crisis, or a temporary deviation from the historical conditions. What we see there is our new normal, and around the world, we are seeing more and more systems getting into this situation, which I have named "water bankruptcy."

SP: What environmental impacts are you most worried about in the next 10 to 20 years?

KM: I have the habit of not prioritizing one environmental problem over another one. Instead, I try to remind people about the interconnectedness of the different environmental problems that the world needs to deal with. But certainly, one of the major environmental problems of the world is the degradation of its water resources in terms of quality and quantity, affecting the natural capital that depends on it and underlies it.

We have ecosystems that heavily depend on water. Examples of this are wetlands downstream of water systems and glaciers upstream of water systems. Other components include rivers, soil moisture, groundwater, snowpacks and so on.

We will also see, as the result of impacts on water resources, some problems becoming more and more serious than before. One of those, for example, is the issue of land subsidence, whose rate is increasing around the world. Another example is the issue of sand and dust storms that are increasing in frequency and intensity around the world. When land becomes dry, not only do we see more destructive flash floods, but also we see wind blowing soil particles and moving them for thousands of kilometers, affecting ecosystems, human health, aviation, energy systems, air quality and so on.

SP: Which parts of the world do you think will see the biggest water problems first?

KM: The water bankruptcy report tells us that, essentially, in every continent where humans are present, water bankruptcy is manifesting itself in a way. While manifestations are different and these problems are different, essentially there is no country that is immune from water bankruptcy.

Water bankruptcy, just like financial bankruptcy, can happen to systems regardless of how water-rich or water-poor they are. Similar to financial bankruptcy, where it doesn't matter how rich or poor you are to begin with, what matters is how you manage your budget. You can be a province in water-rich Canada and become water bankrupt or struggle with water issues — for example, in Alberta — and you can be a Middle Eastern country like Yemen and face issues.

We know that water problems have been an issue in the dry parts of the Middle East or dry parts of the U.S. West, but the report tells us that water bankruptcy can happen also in very wet areas. Water bankruptcy is not only about water quantity; it's also about water quality. We have some places of the world that are wet, like East Asia, for example, or Southeast Asia. And in those places, the quantity is there, but the quality is very bad. The water is polluted and cannot be used, so we should also worry about those places.

Initially we have seen signs of water bankruptcy in the Middle East and North Africa, for example, and in water-stressed areas of the world: the Colorado River basin, parts of Mexico or other dry areas. But you go around the world, and you see that these problems are happening everywhere.

SP: What are the steps countries should take now to avoid a water disaster?

KM: What we have done so far to address our water shortage problems has not been adequate and, in a way, has even intensified or worsened our problem. If we look back and see what we have done, we see that we have mostly focused on increasing water supply through different technological interventions, from digging deeper wells to building dams to transporting water, desalination, recycling and reuse, and so on. What we haven't done enough of is demand control and consumption reduction.

Bankruptcy management is not only about increasing supply but also putting a cap on consumption and reducing expenditure — that's a necessity. Part of this can be done through technology, so technology would be part of the solution. But you also need to implement major policy reforms that lead to the reduction of consumption and getting rid of unsustainable uses. This would affect certain sectors, and to ensure that you don't cause injustice, you have to see which groups are being impacted and how we have to address that.

Countries need to diversify their economies and reduce the pressure of their economies on water and natural resources. In many parts of the world, especially in the Global South, agriculture is the biggest user of water. Many smallholder farmers rely on water for their food production and employment and income — and cutting water from them means unemployment, hunger, migration, tension and so on. Countries must avoid that, and that's only possible if alternative modes of livelihood can be created through the diversification of the economy and creating opportunities in the service and industrial sectors.

SP: What is the worst industry or sector for unsustainable water use, and how can they improve?

KM: It's a strategic mistake if we name one sector as the worst sector and just decide that we have to reduce use only in that sector. Countries are very different in terms of their development stage and the state of their economy, also their geography and resources, so everything depends on the conditions.

Every society, every system, has to do a proper water accounting and see how it is using water within the system. In certain places, the bad user can be the urban sector. In some other places, it might be the industrial sector that is highly polluting, and then in many other places, it can be the agricultural sector that can become much more efficient to help prevent the exacerbation of the problem. It's totally dependent on the location, but we know that the return on investment per drop of water is bigger in certain industries or certain sectors versus other ones.

Countries must look at these numbers to be able to make proper decisions. But let's not also forget that it's not all about the economic return; sometimes countries use water for creating food security and stability through making the employment sector intact. We've got to be careful about naming and shaming one sector and claiming that it's only one sector that we have to focus on, or one method that we have to use across the world, to address water problems.

SP: One sector that is growing and uses a lot of water is AI and data centers. How do you think that will influence water bankruptcy in the future?

KM: AI and data centers rely on a lot of energy for their operations. They impact water resources not only through the water they need for cooling, which is a considerable amount, but also through the water that is used or impacted for producing the energy that they use. It's a new use that is growing, despite the fact that we are already water bankrupt or near-bankrupt in many places.

It is a sector that has a high return on investment, so you can argue that societies can shift water from some other sectors where the return on water use is nowhere [as high] to help this sector grow. But that only makes sense if the benefit generated is distributed and those who lose access to water resources can benefit from the growth of AI and data centers. If, for example, you have a basin where alfalfa is being grown with water, using water for AI and an expansion of data centers [instead] in that location might be a very reasonable move, provided that the alfalfa grower is a beneficiary of that growth and change.

We have to be careful. In some other places, further water investments in data centers might result in compromising food security and the growth of certain strategic foods, and that's something that we should avoid. We know that that sector is getting increased use, and we are already under pressure in many places. This doesn't mean that we should say no to technology; it only means that we have to proactively curb, essentially control and mitigate the impacts, and ensure that introducing new uses would not hurt the system further and result in more irreversible damage.

Editor's note: This interview has been condensed and lightly edited for clarity.

Water use in California was lower than officials estimated it would be between 2000 and 2020, according to a new report.

The findings raise questions about the accuracy of long-term water-demand projections, which could have knock-on effects on costs borne by consumers, but overall the news that water demand is lower than projected is positive for the state and its regular battles against drought, experts told Live Science.

"Overall, I think this is a good news story," Heather Cooley, director of research at the Pacific Institute water think tank in California, told Live Science. "It shows that there are things we can do to ensure we have enough water for people and for nature."

Water management has long been a key issue in California, which has about 8.5 million acres (3.4 million hectares) of irrigated cropland. Crops like grapes, almonds and pistachios anchor the state's economy, creating hundreds of thousands of jobs. Agriculture makes up about 40% of California's annual water use, on average, with another 10% being used by communities and the other 50% being put back into the environment.

But the supplies of this precious resource are often at risk in the state, thanks to lengthy droughts, long-term depletion of groundwater supplies and population growth.

Projections of water use generally assume it will go up as the population increases, but California has introduced many water-saving measures. So to investigate how projections compare with actual usage, Johanna Capone, a graduate student at Virginia Tech, and Landon Marston, an associate professor in the Virginia Tech Department of Civil and Environmental Engineering, assessed the state's Urban Water Management Plans, which were prepared every five years by 61 California urban water suppliers from 2000 to 2020.

They found that water suppliers consistently overestimated future demand by an average of 25% for five-year projections, and 74% for 20-year projections.

This overestimation stems primarily from predictions of how much water each person would use, rather than from assumptions about population growth, Capone and Marston reported in a study published Nov. 21, 2025, in the journal Water Resources Research. While suppliers generally projected stable or increasing per-capita demand, actual water demand per capita declined by 1.9% annually between 2000 and 2020, meaning water demand no longer neatly correlates with population growth.

"I think the overall takeaway is that California has been doing a great job in reducing demand," Capone told Live Science. "The state is clearly on the right path."

The findings match those from other similar research.

"This trend is consistent with what I have seen not only in California but also in other regions," Cooley said. She is an author of a 2020 study that also saw a decline in per capita water use in 10 of California's water suppliers between 2000 and 2015.

She said there has been a gradual decoupling of water use and population growth, so we can no longer assume that the two are linked.

"This study has shown, what other studies have shown, that we can grow and support economic development, using less water," Cooley said, "and efficiency is a key strategy for helping us do that."

Capone credits the reductions in water use to water-related initiatives, educational campaigns and financial incentives — such as rebates for replacing turf with drought-tolerant landscaping — driven by state policies like the California Green Building Standards Code and the Model Water Efficient Landscape Ordinance.

These regulations require that new developments use water-efficient versions of devices like toilets, shower heads, sprinklers and washing machines, Cooley said. It also helps when older versions of these devices are replaced by newer, more efficient models. The new initiatives also address outdoor water use by limiting the amount of grass and other plants that require a lot of water, she said.

"The denser these communities become and the smaller the lawns, naturally water demand is going to drop in much the same way water demand is going to drop as buildings become more efficient," Capone said.

Yet water suppliers should make their forecasts more accurate to account for changes in water efficiency incentives, she said.

"It's a difficult balance, because people may see that water demand is getting lower, and hopefully they wouldn't take advantage of the situation and start watering lawns more," Capone said. "But it's important to try to be as accurate and realistic as possible, because if water demand is over-projected, the water suppliers might get hit by extra costs that would get passed on to customers."

This might require buying in extra water supplies or building new water supply and treatment infrastructure, she said.

The study findings don't mean California's water supply challenges are over. "Even as we've seen declining water use, we still have water supply issues in California as droughts become more intense and more frequent, thanks to climate change," Cooley said.

Wet years help replenish stocks of groundwater that California relies on, but it's the water demand management that ensures enough water remains in reservoirs and in aquifers over the longer term so that when drought returns, the state doesn't have to apply the strictest water-use restrictions, Cooley said.

An analysis from the Metropolitan Water District of Southern California, which serves roughly 19 million people, found that without the district's water efficiency initiatives over the past 30 years, stores of water in that area would have been depleted three times during that period.

"The important thing about water demand management is just to be resilient overall, and to be prepared for all that the environment has to throw at you," Capone said.

One of the biggest challenges is to keep reducing water use as buildings become more efficient and lawns become smaller.

Although water demand per capita declined by 1.9%, on average, annually between 2000 and 2020, a more detailed look at Capone and Marston's paper shows that per-capita water demand dropped around 2.6% per year from 2000 to 2015 but increased by an average of 0.29% per year from 2015 to 2020. These numbers raise questions about whether water demand management efforts have plateaued.

If so, continued cuts in water use might require a different focus. "When you think of water conservation, you think about the advertising, 'Brush your teeth without the water on' and 'If it's yellow, let it mellow,' but it goes so much farther than just the household," Capone said.

It's important to look at where else water is being used and see if building codes and landscaping could reduce that usage, she said.

The potential across the U.S. for making water savings is huge. A November study from the Pacific Institute, which Cooley co-authored, found that improving water efficiency in U.S. homes and businesses, and reducing leakage in distribution systems could save between 14.0 and 34.1 million acre-feet of water per year, or between 12.5 and 30.4 billion gallons (115 billion liters) per day, and that even basic upgrades to meet existing standards could cut water use by one-quarter nationwide.

"There are lots of opportunities for us to reduce water use and make our communities more sustainable and resilient," said Cooley.

The ancient Romans are well known for their advanced water supply systems and hygienic facilities, including public baths and toilets. But the first baths built in Pompeii may not have been particularly pleasant, due to dirty, contaminated water that was replaced only once per day, according to a new study.

"It is very likely that the bathing experience in this small bathing facility was maybe not hygienic and hence not very inviting," study lead author Gül Sürmelihindi, a geoarchaeologist at the Johannes Gutenberg University of Mainz in Germany, told Live Science in an email.

Sürmelihindi and colleagues analyzed the chemical compound calcium carbonate preserved in incrustations in the Republican Baths at Pompeii to investigate the composition of the water supply. Their study was published Monday (Jan. 12) in the journal PNAS.

Public baths were a key part of Roman culture, the researchers wrote in the study, and as the Roman Empire expanded, bathing culture also evolved. At the height of the Roman Empire, the Romans "built long-distance aqueducts in order to have their daily bathing and cleansing experience," Sürmelihindi said.

But in the earliest baths built at Pompeii, which were in use between about 130 and 30 B.C. during the Roman Republic, the situation was different. Before the city constructed an aqueduct, bathing facilities were filled with water from wells and cisterns via a single water-lifting machine that was operated by enslaved people.

"The water could not be replenished more than once a day," Sürmelihindi said. "In this setting, I would expect water to be less clean, especially before the bathing water was refreshed again."

To investigate the composition of the bath water during this time, the researchers studied samples of calcium carbonate, a mineral form of calcium. Calcium carbonate is produced when calcium ions in hard water react with carbonate ions, leading to limescale — a hard, chalky deposit that builds up in kettles, boilers and pipes.

The researchers found that the carbonate in the Republican Baths showed a strong decrease in carbon isotopes (variations of the element with different numbers of neutrons) between the well that supplied the water and the heated pools where people bathed. The lowest carbon isotope values were found in areas where the water drained, meaning the main cause was likely "the introduction of organic carbon from microbial activity and human waste (e.g., sweat, sebum, urine, bathing oil)," the researchers wrote.

"These baths were an experience we do not have nowadays," study co-author Cees Passchier, a geoarchaeologist at the Johannes Gutenberg University of Mainz, told Live Science in an email. "People would not use soap, but olive oil to rub in and scrape the dirt off, and some of that oil would land in the water."

The water in the heated pools of the Republican Baths shows "high contamination by human waste," suggesting that it was not replenished regularly and that it offered "poor hygienic conditions for the Pompeiian bathers," the researchers wrote.

The researchers also investigated heavy-metal contamination in the baths by analyzing traces of elements left there. In the Republican Baths, the team identified elevated levels of lead, a toxic element that was likely introduced through the lead-pipe system in the bathing complex. Over time, though, the gradual incrustation of the pipes with calcium carbonate would have reduced the water's lead level.

It's unclear whether the murky water would have kept people away.

"Everyone mixed in the baths, regardless of social class, and the price was low," Passchier said. But if the water was really gross and smelly, he said, the baths would not have had customers. "People probably did not spend much time in the warm pools, which were small, but mostly spent time sitting around in the warm air of the hot bath having a conversation," he said.

Pompeii quiz: How much do you know about the Roman town destroyed by Mount Vesuvius?

The patient: A man in his 20s in China

The symptoms: A man went to the dermatology department of a hospital after experiencing an array of symptoms for about three years. When he submerged his hands in water, such as during hand-washing, the skin on the back of the man's hands thickened and became overly wrinkly, with white bumps and growths appearing.

Whenever this occurred, his hands felt very itchy and like they were burning, and the symptoms were worse in the summer months, he told doctors. Symptoms did not arise during winter, and his palms were unaffected year-round.

The man had previously sought treatment at his local clinic, where he was diagnosed with chronic eczema — which causes skin to become dry, thick and itchy — and prescribed a strong retinoid ointment, which he used intermittently. However, this treatment didn't work, and his symptoms gradually worsened. His wrists and elbows had also started to develop the skin lesions over the 1.5 years prior to the hospital visit.

The patient had no family history of similar skin conditions and did not experience excessive sweating or have any allergies, and he had never injured his hands. The man attributed the worsening of his condition to him washing his hands more frequently during the COVID-19 pandemic, the doctors wrote in the report of the case.

What happened next: During a physical examination at the hospital, the man's hands were immersed in water for 10 minutes, immediately causing the tops of his hands, fingers and wrists to grow red, scaly and wrinkly with white lesions. Notably, the "excessive wrinkling" and bumps ended in a straight line on the sides of his hands, leaving his palms unaffected.

The doctors took biopsies from the white bumps on his right hand, which revealed that the sweat ducts in the top layer of skin had widened and contained more sweat glands than normal. The results also showed he had hyperkeratosis, meaning his body was producing too much of the protein keratin, causing the outer layer of skin to thicken.

The medical team wrote that "the patient's clinical process was quite interesting," because the symptoms of the skin condition appeared only after his hands were immersed in water and all symptoms disappeared around 30 minutes after his hands dried.

The diagnosis: The doctors diagnosed the patient with a condition called aquagenic syringeal acrokeratoderma (ASA) based on how his symptoms appeared in the clinic and the results of the biopsy. In almost all other cases, however, it affects the palms of the hands, not the backs of the hands or fingers.

The short-lived symptoms of this skin disease are known as the "hand in the bucket sign," because they occur after the hands are submerged in water. The symptoms normally disappear within a few hours of drying, but a subset of people with ASA have persistent skin lesions that are aggravated by water exposure, according to the Genetic and Rare Diseases Information Center (GARD).

The cause of ASA is currently unknown, but it may be linked to "an acquired sweat gland abnormality" or some trigger that causes thickening of the skin, according to research published in the Journal of the American Academy of Dermatology.

The treatment: The patient was treated with topical hydrocortisone urea ointment, which is a corticosteroid and skin moisturizer that can be applied directly to the affected area. It is typically used to treat skin irritation, swelling and redness.

The doctors also recommended that the patient avoid getting his hands wet more than what was strictly necessary. The man was still attending follow-up appointments when the doctors wrote about his case, and they noted that his symptoms had eased substantially after just one month.

What makes the case unique: ASA is thought to be a rare condition, although its exact prevalence is unknown.

Data suggests the condition is most common in female adolescents, the case report authors noted. It also occurs in about 40% to 84% of cystic fibrosis (CF) patients and carriers, meaning people who have just one copy of the CF gene mutation, according to GARD. (You need two copies to develop CF.) This pattern hints at ASA being caused in part by mutations in that gene, at least in some cases.

The patient described in this case was the first known to have ASA that didn't affect his palms, the doctors wrote in the report. It's unclear why his case manifested differently than others previously reported.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

When you're waiting for a pot of water to heat up on the stove, tiny bubbles are the first sign it's getting ready to boil. As the water gets hotter, the bubbles get bigger, until a rolling boil signals the water has reached 212 degrees Fahrenheit (100 degrees Celsius).

Or does it? Anyone who has boiled water in a microwave will note the lack of bubbles. So, why does boiling water have bubbles, except in a microwave?

According to fluid dynamists, nanoscale bubbles constantly appear and collapse as the water heats up over a heating source like a stove. But the temperature at which noticeable bubbles start to form could sometimes be much higher than water's boiling point on paper.

"The boiling point means that at anything above that temperature, your molecules are happier being a vapor than being a liquid," said Jonathan Boreyko, a fluid dynamist at Virginia Tech. Beyond 212 F, the intrinsic energy of the water molecules — known as the chemical potential — is lower for the gas than the liquid, making the vapor the most stable form.

"But to actually execute boiling, you have to create a bubble, which has an energy cost," Boreyko told Live Science. "So just because you're happier being a vapor doesn't mean you'll successfully boil."

Therefore, the temperature at which water actually boils is a trade-off between the chemical potential energy saved by becoming a gas and the energy spent to form a bubble.

Crucially, a bubble is not just a volume of gas but also an interface between gas and liquid phases. And like all liquid interfaces, this surface is subject to surface tension.

Surface tension is a force that constantly tries to shrink the gas-liquid boundary to the smallest possible area. In the case of a bubble, this would mean collapsing entirely back into a uniform liquid. A stable bubble must therefore contain enough gas that the chemical potential energy saving is greater than the surface tension of the interface, making larger bubbles more stable.

"Surface tension is basically an energetic cost per area," Boreyko said. "Really small bubbles have a very large surface-area-to-volume ratio, whereas a bigger bubble has a smaller area relative to its volume. The volume dominates the bigger you get, which outcompetes the surface tension cost."

Consequently, water often doesn't boil until it's a little hotter than 212 F — a phenomenon known as superheating. The boiling point marks the temperature at which the gas becomes more stable than the liquid, and the extra degrees correspond to the activation energy required to create a sufficiently large bubble.

However, various factors influence how easily these bubbles can form, Mirko Gallo, a fluid dynamist at Sapienza University of Rome, told Live Science.

"Dissolved gases, impurities in the water, the surface of the container can all reduce the energy barrier for the formation of the bubble," Gallo explained. These irregularities within the bulk liquid provide a distinct nucleation point around which bubbles can form, reducing the surface tension penalty of forming a completely spherical bubble.

"If you form a bubble on an edge, it is only half a sphere, so you have a smaller surface and will need less energy," he added. "That's why the first bubbles always start appearing on the boundary of the pot."

Boiling water in microwaves

Conversely, in a microwave, the unusual heating conditions suppress bubble formation so effectively that it's possible to superheat the water by up to 36 F (20 C).

"The electromagnetic waves are penetrating and exciting the water molecules through the entire volume, so it heats the water very quickly and uniformly, whereas on a stovetop, it's the bottom wall of the pot that's getting hottest," Boreyko explained. "You also tend to [heat up things in a microwave] in a pretty smooth container — say, glass — so you don't have those localized hotspots that help you get over that energy barrier to create the first interface."

This huge store of chemical potential energy in the superheated liquid is spontaneously released in the form of a giant, explosive bubble as soon as the container is disturbed, making water heated in the microwave surprisingly dangerous.

But superheating isn't exclusive to water; it's possible for any liquid, Gallo said.

"Water has a very high surface tension compared to most liquids, but basically, the higher the surface tension, the more dramatic the effect," Boreyko added.

Scientists have created a three dimensional map of a distant planet's atmosphere for the first time.

Using data from the James Webb Space Telescope (JWST) and a technique known as eclipse mapping, researchers found different temperature zones in the atmosphere of the exoplanet WASP-18b, a gas giant located about 400 light-years from Earth. The same process could soon help scientists map temperature variations and cloud structures on other faraway planets, according to a study published Oct. 28 in the journal Nature Astronomy.

"Eclipse mapping allows us to image exoplanets that we can't see directly, because their host stars are too bright," study co-author Ryan Challener, a researcher studying exoplanets at Cornell University, said in a statement. "With this telescope and this new technique, we can start to understand exoplanets along the same lines as our solar system neighbors."

WASP-18b has about 10 times the mass of Jupiter, and its year is just 23 hours long. It's tidally locked to its star, which means one side of the planet constantly faces the star, while the other side is always dark.

As a planet starts to pass behind its star, the star blocks more and more of the light that the planet reflects, until the planet is fully obscured when viewed from our solar system. Eclipse mapping takes advantage of this progressive change. By measuring how the light from a planet changes as it's obscured and revealed, scientists can work out the temperature in different regions and altitudes of the planet's atmosphere.

"You're looking for changes in tiny portions of the planet as they disappear and reappear into view, so it's extraordinarily challenging," Challener said.

In the new study, the scientists built on a previous two-dimensional temperature map of WASP-18b by using different wavelengths of light to create a more detailed, 3D map of the atmosphere. For example, they used data of a wavelength that is absorbed by water to map the exoplanet's wet upper atmosphere. Wavelengths that water didn't absorb passed through to lower altitudes, allowing JWST to preferentially look at different levels of the planet’s atmosphere based on the wavelengths it was studying.

WASP-18b has two distinct temperature regions on its day side, the team found. It has a circular "hotspot" in the area that directly faces the star and receives the most sunlight. Beyond that is a colder ring that extends to the visible edge of the planet. This suggests that atmospheric winds can't fully redistribute the heat from the star across the planet.

The scientists also observed less water in the hotspot than the planet's average. This could mean that temperatures in the hotspot are high enough to rip apart water molecules in the atmosphere, the researchers suggested.

"We think that's evidence that the planet is so hot in this region that it's starting to break down the water," Challener said. "That had been predicted by theory, but it's really exciting to actually see this with real observations."

Additional measurements with JWST could boost the resolution of WASP-18b's atmospheric map and enable scientists to study the atmospheres of other gas giants like it.

"This new technique is going to be applicable to many, many other planets that we can observe with the James Webb Space Telescope," Challener said. "We can start to understand exoplanets in 3D as a population, which is very exciting."

Scientists have squeezed water between two diamonds to create an entirely new form of ice that's solid at room temperature.

The ice, named ice XXI, forms when water is subjected to extreme pressure to become metastable — a precarious state that is made physically unstable by the slightest disturbance.

The researchers created ice XXI by supercompressing water between two diamonds and detected it with the European X-Ray Free-Electron Laser (XFEL), the world's largest X-ray laser. The team found that the supercompressed water structurally changes from a high-density state to a very-high-density state.

The finding could have implications for space exploration, opening up new ways that ice could potentially form on alien worlds, according to the study published Oct. 10 in the journal Nature Materials.

"Our findings suggest that a greater number of high temperature metastable ice phases and their associated transition pathways may exist, potentially offering new insights into the composition of icy moons," study co-author Rachel Husband, a postdoctoral researcher at the German Electron Synchrotron research center in Germany, said in a statement.

Ice XXI, the number 21 in Roman numerals, is the 21st known ice phase — others include the four-sided crystals of ice XIX and star-hot superionic ice. Water can exist in a plethora of solid phase forms thanks to its molecular structure, with its two-pronged hydrogen atoms freezing into varying crystalline and amorphous structures.

Scientists have found many water-ice transition pathways by applying pressure to water at low temperatures, when molecules are slower, but they expect less ice diversity at higher temperatures, when the molecules have more kinetic energy.

In the new study, the researchers explored ice transition pathways at room temperature, which is around 72 degrees Fahrenheit (22 degrees Celsius). The team used a diamond anvil cell, a device that takes advantage of the extreme hardness of diamonds to subject materials to immense pressure. In this case, water was subjected to pressures of around 20,000 times that of normal air on Earth, forcing H2O molecules together until they were so compact they formed a solid structure. The XFEL scanned the sample every one millionth of a second (1 microsecond), tracking how its structure changed.

"With the unique X-ray pulses of the European XFEL, we have uncovered multiple crystallization pathways in H2O which was rapidly compressed and decompressed over 1,000 times using a dynamic diamond anvil cell," study co-author Geun Woo Lee, a researcher at the Korea Research Institute of Standards and Science (KRISS), said in the statement.

Scientists in Japan now believe that liquid water once flowed through the heart of the near-Earth asteroid Ryugu, after researchers detected something unusual in the samples of the space rock that were returned to our planet five years ago.

The surprising findings also have potential implications for how Earth acquired its own water, the researchers say.

162173 Ryugu is a roughly 3,000-foot-wide (900 meter) asteroid that orbits the sun every 474 days on a trajectory that frequently overlaps with Earth's. It is unlikely to ever hit our planet, but it is still large enough and comes close enough to us to be considered "potentially hazardous" by NASA.

Ryugu was visited by Japan's Hayabusa2 mission between 2018 and 2019, which deployed a probe that landed on the spinning top-shape space rock and collected samples that were later returned to Earth in December 2020.

In a new study, published Sept. 10 in the journal Nature, researchers unearthed chemical irregularities within these samples, which they say can currently be explained only by the historic presence of flowing water within the asteroid.

"We found that Ryugu preserved a pristine record of water activity," study lead author Tsuyoshi Iizuka, a geochemist at the University of Tokyo in Japan, said in a statement. There is also "evidence that fluids moved through its rocks," he added. "It was a genuine surprise!"

Related: Key building block for life discovered on distant asteroid Ryugu — and it could explain how life on Earth began

The new findings emerged after the team analyzed the radioactive isotopes — rare versions of elements with an altered atomic mass — of lutetium (Lu) and hafnium (Hf) within the samples.

Lu-176 naturally decays into Hf-176 via beta decay, in which an element spits out charged subatomic particles, such as electrons or positrons, transforming them into something else. By working out the ratio of Lu-176 to Hf-176 and comparing it to the half life of Lu-176 — the time taken for half a sample of the isotope to naturally decay — the team aimed to work out how old the samples were.

But when they carried out their analysis, the researchers found that there was far too much Hf-176 in the samples. The researchers argue that the only thing that could properly explain this result was that ancient liquid water had washed away a majority of Lu-176 within the samples, which could have started happening shortly after Ryugu was born.

A watery past

"The most likely trigger [for the water] was an impact on a larger asteroid parent of Ryugu, which fractured the rock and melted buried ice, allowing liquid water to percolate through the body," Izuka said.

Recent analysis from the James Webb Space Telescope (JWST) had suggested that Ryugu's parent asteroid may have also spawned the asteroid Bennu, which was visited by NASA's OSIRIS-REx mission that later returned samples of the asteroid to Earth in September 2023. However, similar signs of flowing water have not been seen within Bennu's samples so far, creating uncertainty about the asteroids' respective origins.

Given that Ryugu likely had flowing water, the researchers also believe that its parent asteroid may have contained ice for at least a billion years after the solar system was formed, which is far longer than most asteroids were thought to be able to hold onto their water.

"This changes how we think about the long-term fate of water in asteroids," Izuka said. "The water hung around for a long time and was not exhausted so quickly as thought."

It is widely accepted that a majority of Earth's water likely came from impacts with asteroids, comets or other planetesimals in the early days of the solar system. The new findings hint that asteroids could have played a much larger role in this process than previously thought, potentially delivering up to three times more water to our planet than expected, the researchers claim.

The study team is now planning to analyze veins of phosphate within the samples, which could pin down a more accurate age for the water that flowed through Ryugu, and look more closely at the isotopes from asteroid Bennu to see if it too has signs of flowing water, according to Live Science's sister site Space.com.

Early Earth was a barren wasteland incapable of supporting life until a big protoplanet crash carried in the necessary ingredients, a new study suggests.

That collision of the proto-Earth and a Mars-size body — nicknamed Theia — has been theorized for decades, especially in discussions of how our moon may have formed from the resulting pieces of the crash.

Now, in a new study, scientists say Theia also brought some of life's key ingredients to our world, more than 4 billion years ago.

"We conclude that the moon-forming impactor Theia originated further out in the solar system [than Earth] and was volatile-rich," study lead author Pascal Kruttasch told Live Science in an email. Kruttasch was a doctoral student at the University of Bern when he performed the study.

Volatiles are chemical compounds that can easily be vaporized, like hydrogen and carbon, but are also considered the building blocks of life. Closer to the sun, temperatures are too high for these materials to condense, meaning they remained in a gas phase near the early Earth and other rocky planets. Farther out, however, there is an abundance of volatiles for gas giant planets like Jupiter and Saturn — as well as comets and asteroids.

Theia was therefore a big deal for Earth, Kruttasch said: It likely shipped these volatiles, which are "essential ingredients for life."

In the study, the researchers used a chemical model to examine isotopes (element types) from meteorites, as well as rocks on Earth.

Related: James Webb telescope images reveal there's something strange with interstellar comet 3I/ATLAS

The team zeroed in on the radioactive decay of an isotope of manganese, which existed in the early solar system and slowly decayed to chromium over several million years This decay timeline enabled the researchers to precisely track the first 15 million years of Earth's formation. (The solar system itself is roughly 4.5 billion years old.)

Figuring out how life got to Earth and remained for billions of years is a complex issue. "Earth is the only planet we know of that has produced life and sustained it for several billion years. It is unclear what processes took place in Earth's history to make this possible," Kruttasch said.

But peering back at the early solar system gave the team some clues. Proto-Earth and growing planets nearby (which today include Mercury, Venus and Mars) changed quickly in their first 3 million years in an exchange of dust and gas through evaporation and condensation.

However, this exchange process practically ceased after 3 million years because the first rocky planets and gas planets had taken up much of the free matter in our solar system. Simply put, planets closer to the sun were more depleted of volatile elements than those that were farther away due to the higher temperatures of the inner planets closer to the sun.

That's why Earth's volatiles must have come from a large source like Theia, which is estimated to have collided with our planet roughly 4.5 billion years ago. (In line with other studies, the new work assumes Theia is a type of chondrite, which is a stony material rich in carbon and organic compounds that tends to form far out from the sun.)

The larger implication of these findings is that life may be difficult to conjure on exoplanets that are similar to Earth, given that most volatiles may have formed in a different region of the solar system. "This [study] makes it clear that life-friendliness in the universe is anything but a matter of course," study co-author Klaus Mezger, a professor emeritus of geochemistry at the University of Bern, said in a statement.

The researchers published their findings Aug. 1 in the journal Science Advances. However, this wasn't the only recent study to discuss Theia and its impact on Earth's life.

Unrelated research slated to be published in the Nov. 15 issue of the journal Icarus suggests Theia delivered a lot of water to our planet — and is still visible in the mantle of our planet.

This mantle water is a puzzle to geologists, because "water is less dense than the materials typically found in the Earth's mantle, and it was supposed to have come to the crust or oceans," study co-author Pedro Machado, an astrophysicist at Portugal's Institute of Astrophysics and Space Sciences, said in a translated statement.

The simulation-based study suggested that Theia delivered much of the water in the mantle to the early Earth, "and there hasn't been time for this water to reach the surface," Machado added.

Scientists have developed a new method to break down harmful "forever chemicals" by exposing them to a sunlight-activated material.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are chemicals found in many household products, including cookware, cosmetics, dental floss and waterproof clothing. True to their nickname, the chemicals take thousands of years to break down, enabling them to accumulate in the environment and our bodies.

PFAS have been used since the 1940s. Initially, they were valued for their nonstick properties, but now they are linked to a number of health impacts, including increased risks of autoimmune disease, developmental disorders, reduced fertility and cancer in humans. This has led some PFAS to be banned. But with nearly 15,000 types having been produced, roughly 98% of the U.S. population has these chemicals in their blood.

Now, a team of researchers has found a way to break down the chemicals, reducing them to components that include fluoride, which is harmless at low doses. They published their findings July 25 in the journal Small.

"PFAS contamination continues to pose a global health risk, and this research represents a critical step toward safer communities and cleaner ecosystems," lead researcher Cameron Shearer, a materials scientist at the University of Adelaide in Australia, said in a statement.

Related: Scientists find a simple way to destroy 'forever chemicals' — by beheading them

PFAS owe their persistence to their strong chemical bonds; they consist of a head (often charged oxygen molecules) linked to a tail of carbon and fluorine atoms. For PFAS to degrade, this bond must be broken — but this process is very difficult to achieve using traditional methods.

"Many water contaminants are degraded by adding a reactive chemical that binds to the carbon," Shearer said. "However, in PFAS molecules, the carbon atoms are protected in such a way that makes this process nearly impossible."

In recent years, researchers have been developing methods to break down PFAS using materials called photocatalysts, which absorb incident light to speed up chemical reactions. The scientists behind the new study turned to a photocatalytic material called cadmium indium sulfide, known for its ability to release reactive oxygen species — or free radicals — after being exposed to visible light.

After mixing the material with one common PFAS called perfluorooctane sulfonate (PFOS), the researchers watched as the photocatalyst absorbed light to generate free radicals that attacked the fluorine atoms in the bond.

Under optimized conditions, this led to the "complete breakdown" of around 99% of the PFOS molecules. The byproducts were components which the scientists say can be isolated and used to make toothpaste and fertilizer additives.

"The materials we have developed through our research could be used as part of PFAS-treatment chains that first capture and concentrate PFAS in water, which can then be degraded through exposure to our light-activated materials," Shearer said. "We plan to build on this study through our ongoing work improving the stability of the materials before they can be applied to large scale systems."

Unlike humans, frogs and other amphibians don't need to rely on their lungs to breathe; their unique skin helps them exchange oxygen and drink. But how do frogs breathe and drink through their skin?

Frog skin is complex: It's thin, covered in glands that produce mucus to keep the skin moist, and porous enough to allow air molecules to permeate.

"[Their skin] is designed to allow both oxygen to get into the skin, and water to be absorbed," Christopher Raxworthy, a curator and herpetologist at the American Museum of Natural History in New York, told Live Science.

A network of small blood vessels right underneath the skin absorbs oxygen directly from water or the air, and also allows carbon dioxide to be driven out of the body in a process called cutaneous respiration, explained Kurt Schwenk, an evolutionary biologist at the University of Connecticut who has studied the breathing mechanisms of frogs and tadpoles. "It's really almost identical to a lung system," Raxworthy added.

Although frogs can also breathe through their lungs and the lining of their mouth, cutaneous respiration allows frogs to survive underwater and through long hibernations. "Almost without trying, just having skin that's moist, and having some blood vessels in it, they're going to exchange gas and water through their skin, whether they like it or not," Schwenk said, although not all frogs depend on cutaneous respiration equally.

Meanwhile, tadpoles don't have developed gills yet, so they need to breathe in air from the surface to survive. But when they're hatchlings, they're too small to break water's surface tension. Instead, they create their own air bubbles. In a 2020 study, Schwenk and his colleague observed the tadpoles swim right below the surface, where they quickly suck in air, forming a bubble. Then, they push the air bubble into their lungs.

Related: Can turtles really breathe through their butts?

Frogs' porous skin is also how they drink. "That water is getting into all those spaces in the skin, and is then being absorbed across cell membranes into cells and into the bloodstream," Schwenk added. Many frogs even have a highly vascularized area on their skin called a "drinking patch," through which they can absorb a large amount of water.

Some frogs found in arid areas — like the trilling frog and the water-holding frogs living in Australian deserts — are especially adept at absorbing water during rainy seasons. "They store it, and then they go into burrows, into the ground, and sometimes they might even put an extra layer of mucus around them, and then they can survive on that water that they stored internally for months or even years until the next rains come," Raxworthy explained.

Although it's a handy tool, their skin's permeability also means frogs and other amphibians are especially vulnerable to pollutants and climate change, Schwenk said. Studies have shown that the permeability of frog skin routinely exposes the animals to commercial chemical products and microplastics. And because frogs need to keep their skin moist to survive, the increased droughts and warmer weather scientists predict from climate change could shrink frog habitats, especially in the Amazon rainforest and the Atlantic rainforest in Brazil, Argentina and Paraguay.

"Amphibians tend to be some of the first groups that you start seeing declining or disappearing, and that usually is an indication of a problem within the environment," Raxworthy said. Losing frogs, in turn, changes the balance of an ecosystem because of their position on the food chain: They keep insect populations under control and are prey for snakes and birds.

Time will tell if some frog species will adapt to a changing climate. "A question that runs through all climate change biology is whether any particular species is subject to climate change, which is all of us, can adapt fast enough," Schwenk said. "In most cases, climate change is happening much faster than animals can adapt."

Animal quiz: Test yourself on these fun animal trivia questions

One of the most enduring stereotypes about domestic cats is that they absolutely despise getting wet. From frantically scrambling out of the bathtub to recoiling at the mist from a spray bottle, cats and water always seem to be at odds. And while some felines might not mind a swim — certain breeds, including Turkish Vans and Maine coons tend to adore the water — many cat owners know that this stereotype still rings true for their fur babies.

But why do cats hate water so much?

There isn't any dedicated scientific research on cats' relationship with water. But there are some potential clues in cats’ biology and evolutionary history, experts say, as well as in their individual upbringing.

Kristyn Vitale, an animal behaviorist and founder of Maueyes Cat Science and Education, suspects that the ancestor of the domestic cat, the African wildcat (Felis silvestris lybica), may play a big role in why modern domestic cats avoid water.

Some wild cats, such as tigers, fishing cats and jaguars, like to swim in order to escape bugs, cool off and even ambush their prey. But the African wild cat mostly lives in desert environments, where it rarely encounters large bodies of water or swims.

"They are not particularly known for hunting near water or within the water," Vitale told Live Science in an email. "A large proportion of the African wildcat’s diet is made up of terrestrial animals, like rodents. Given this, it is not surprising that domestic cats don’t really seek out water. It is just not something this species was built to do."

However, Jonathan Losos, a professor of biology at Washington University in St. Louis and author of "The Cat's Meow: How Cats Evolved from the Savanna to Your Sofa" (Viking, 2023), told Live Science in an email he isn't totally convinced by this theory. He pointed out that just because an animal is from a desert doesn't mean it fears water, and that the range of African wildcats also extends to some less arid habitats — meaning some members of the species do encounter water in their lifetimes.

Jennifer Vonk, an animal cognition expert at Oakland University, brought up another potential reason house cats don't like water: being wet is physically uncomfortable and can potentially disrupt their sense of smell.

Related: Why do cats make a weird face after smelling something?

"Their fur does become waterlogged and make movement more cumbersome, which probably leaves them feeling vulnerable," Vonk told Live Science in an email.

Water can also mask a cat's natural odor, or bring with it new smells that cats are sensitive to. Cats may be able to detect chemical cues in tap water that they find unpleasant, Vonk said, and Vitale noted that getting wet may obscure a cat's natural pheromones, which could cause distress.

Ultimately, cats' hatred of water may not stem from a single source — it's probably a blend of multiple factors.

"It is likely a combination of being a natural aversion and a learned behavior," said Vitale.

On that note, a kitten's early experiences could play a big role in how they feel about water for the rest of their lives. While there's no direct research about whether exposing kittens to water makes them like it more, cat experts do know that exposing kittens to different sights, sounds, scents, textures and experiences helps them become more confident adults. This process is called socialization, and Vitale said it could apply to water as well.

"It is likely that if a kitten grew up around water, they would be more comfortable around water as an adult," she explained. "With that said, every cat is an individual. Even with water exposure, some kittens may still show water aversion, while other kittens who have never been exposed to water might enjoy it."

Cat quiz: Can you get a purr-fect score?

Tremendous tilts of Mars' rotational axis during the past 20 million years may have dried out the planet, according to a new study. The findings may help solve the mystery of how Mars, which once contained lakes, rivers and possibly oceans, lost its water.

Dry, dust-filled deserts cover much of Mars' surface today. Astronomers think most of the planet's scant water reserves are frozen within fine-grained surface dirt, with above-surface ice confined to the polar regions.

But the Red Planet hasn't always been so dry. Gullies, lake beds and valleys photographed by early NASA missions like the Viking project suggest that since Mars' birth, the planet's surface has been periodically inundated by billions of gallons of liquid water. In fact, planetary scientists have calculated that the volume of water that carved out these geological features amounted to a layer at least 300 feet (100 meters) thick over the planet's entire surface.

One hypothesis for where the water went is that much of it was "boiled" off. In a joint email to Live Science, Gabriella Gilli and Francisco González-Galindo, astronomers at the Astrophysics Institute of Andalusia in Spain and the new study's first and second authors, respectively, explained this process.

Water vapor in the Martian atmosphere — kicked high up by powerful dust storms — would have separated into atomic hydrogen and oxygen due to the sun's powerful ultraviolet radiation. A fraction of this lightweight atmospheric hydrogen would have been sufficiently energetic to escape into space.

"Given that ultimately the hydrogen in Mars' atmosphere comes from water, the escape of hydrogen atoms involves the loss of water molecules," Gilli and González-Galindo said.

Related: Mars rover captures first close-up photos of giant 'spiderwebs' on the Red Planet

Measurements by NASA's ongoing Mars Atmosphere and Volatile Emission mission suggest that, at present, approximately 100 trillion trillion hydrogen atoms exit Mars' atmosphere every second. But estimates — using this present-day escape rate — of the total water Mars has lost over its 4 billion-year lifetime are, at best, only a quarter of the amount calculated to have sculpted the various geological features. In other words, most of Mars' historic water loss can't be explained by this mechanism alone.

To resolve this discrepancy, the new study's authors proposed a different idea: that Mars lost much more water when its axis of rotation was enormously tilted in the past. Today, Mars' tilt, or obliquity, is 25.2 degrees relative to its orbital plane around the sun, similar to Earth's 23.5 degrees. However, the Red Planet's tilt hasn't remained stable over the past several million years.

"The main reason is that Mars, contrary to the Earth, does not have a massive satellite (the Moon), which plays a major role in stabilizing the orbital variations of the planet," Gilli and González-Galindo said. As a result, Mars has gyrated wildly between 0 degrees and a massive 66 degrees, averaging 35 degrees.

The researchers hypothesized that as Mars tilted more, its north pole received more sunlight, which likely would have melted more ice and increased the amount of atmospheric vapor that could escape. Daniel Lo, a postdoctoral researcher at the University of Michigan who wasn't involved in the study, agreed with this reasoning, telling Live Science by email that "during intervals of increased axial tilt for Mars, global temperatures actually increased, and some of the water ice [across the planet] would sublimate into water vapour."

To test their hypothesis, the new study's authors turned to a computational simulation called the Mars Planetary Climate Model, "among the best that we currently have for the Martian atmosphere," Lo said. The team virtually changed the planet's tilt to 30 degrees and 35 degrees, and tracked the amount of hydrogen lost over a Martian year. They also evaluated the impact of dust storms using real data.

The analyses revealed that such storms increased hydrogen losses by up to 50%, depending on the storm's strength. But the real eye-opener came with the obliquity results: At a 35-degree tilt, an average of 19 more hydrogen atoms (compared to present-day values) escaped every second from Mars' atmosphere. This corresponds to a Martian yearly loss of a billion more hydrogen atoms compared with today's hydrogen losses. Gilli and González-Galindo noted that this would translate to Mars having the equivalent of a 260-foot-thick (80 m) global layer of water over its lifespan — close to the lowest geological estimate for its water content.

The findings, published May 21 in the journal Nature Astronomy, showed that changes in the planet's tilt substantially increased the amount of hydrogen — and thus water — that was lost.

"It suggests that the atmospheric thermal escape played a larger role than thought in drying the planet," Gilli and González-Galindo said. However, they noted that factors such as the planet's dust composition likely differed from present-day values and also may have influenced water loss.

The Pacific Ocean is by far the world's largest ocean, more than five times wider than our moon. But why is the Pacific so big?

Covering about 63 million square miles (163 million square kilometers) — more than 30% of Earth's surface — all of the world's continents could fit inside the Pacific basin, according to the National Oceanic and Atmospheric Administration (NOAA). The Pacific, which holds more than half of the free water on Earth, is also our planet's deepest water body, extending to a depth of more than 36,000 feet (11,000 meters) at Challenger Deep in the Mariana Trench, NOAA noted.

The predecessor of the Pacific Ocean was Panthalassa, or the Panthalassic Ocean, which was once Earth's only ocean. This world-spanning superocean existed when all of Earth's continental land was united in the supercontinent Pangaea.

"Panthalassa was the proto-Pacific," Susanne Neuer, founding director of the School of Ocean Futures at Arizona State University in Tempe, told Live Science. "The Pacific is essentially what remains of Panthalassa."

Oceans and continents past and present rest on top of tectonic plates, the giant slabs of rock that make up Earth's rigid outer shell. These plates are regularly on the move, sometimes colliding into each other, sometimes pulling apart from one another. About 230 million years ago, such motions led Pangaea to start breaking up.

"What became North America and Eurasia began to pull apart from what became South America and Africa and Antarctica and Australia," Adriane Lam, an assistant professor of Earth sciences at Binghamton University in New York, told Live Science.

Related: Do the Pacific Ocean and the Atlantic Ocean mix?

Eventually, Pangaea split apart. In the gap that emerged between the continents, the Atlantic Ocean was born. "The Atlantic is growing about two to three centimeters each year, or about an inch," Neuer said. "That doesn't sound like much, but when you multiply that by millions of years, it's a lot."

As the continents making up Pangaea were pushed apart, Panthalassa shrunk. At the "subduction zones" where these continental plates slid over Panthalassa's oceanic plates, the "Ring of Fire" emerged, a zone infamous for volcanoes and earthquakes surrounding what is now the Pacific Ocean, Neuer explained.

A 2016 study in the journal Science Advances revealed that about 200 million years ago, the Pacific Plate, the tectonic plate that now underlies the Pacific Ocean, was born at the junction of three tectonic plates under Panthalassa, dubbed Farallon, Phoenix and Izanagi.

"The most modern analogy with what happened with the Pacific can be found today with the Afar triple junction in East Africa, where you have three plates meeting together — the Nubian, Somali and Arabian," Lam said. "But at the Afar triple junction, those plates ultimately failed to pull apart. With the Pacific triple junction, those three plates succeeded, forming the Pacific Plate."

As the Pacific Plate expanded, it displaced these three older plates. The Izanagi Plate was pushed under Asia. Nearly all of the Farallon Plate was driven beneath North America, although remnants of it remain off North America's west coast. And "the Phoenix Plate is nothing but a small piece between the southern tip of South America and the Antarctic Peninsula, the area of ocean called the Drake Passage," Lam said.

Although the Pacific is currently the world's largest ocean, "it's getting smaller" as the Atlantic gets bigger, Lam noted. However, at 41 million square miles (106 million square kilometers), the Atlantic is still much smaller than the Pacific. And a 2024 modeling study predicts that the Atlantic will start shrinking in about 20 million years.

For Lam, the Pacific Ocean is one of a kind, she said, noting its size, geological history and geological complexity. "The Pacific is the most amazing ocean basin of all."

Mariana Trench quiz: How deep is your knowledge?

Mysterious dark streaks flowing across Mars's surface may not be the result of running water after all, a new artificial intelligence (AI) analysis suggests.

The streaks, first observed running along Mars's cliffsides and crater walls by NASA's Viking mission in 1976, were long thought by scientists to have formed as a result of the flow of ancient water across the now mostly desiccated planet's surface.

But an AI algorithm trained on slope streak observations has revealed a different origin for the streaks — likely being formed from wind and dust, not water. The findings, published May 19 in the journal Nature Communications, could have important implications for where humans choose to explore Mars, and the places they search for evidence of possible ancient life.

"That's the advantage of this big data approach," study co-author Adomas Valantinas, a planetary scientist at Brown University, said in a statement. "It helps us to rule out some hypotheses from orbit before we send spacecraft to explore."

The sinewy lines are darker than the surrounding Martian ground and extend for hundreds of meters downhill. The shorter-lived of these features are called recurring slope lineae (RSL), and regularly spring up during Mars's warmer spells.

This led some planetary scientists to suggest that seasonal temperature fluctuations could be causing ice or frozen aquifers to melt, or humid air to condense, sending streams of salty water trickling down the planet's craters. If this were true, it would make these regions of particular interest to future Mars missions.

Related: Curiosity rover finds largest carbon chains on Mars from 3.7 billion-year-old rock

To investigate this, the scientists behind the study trained a machine learning algorithm on confirmed streak sightings before making it scan through 86,000 satellite images to create a map of 500,000 streak features.

"Once we had this global map, we could compare it to databases and catalogs of other things like temperature, wind speed, hydration, rock slide activity and other factors." Bickel said. "Then we could look for correlations over hundreds of thousands of cases to better understand the conditions under which these features form."

Using the map, the scientists found the streaks were most likely to form in places where wind speed and dust deposition was high, suggesting that they came from layers of fine dust sliding off steep slopes.

Other studies have pointed to tantalizing evidence of water and even life on Mars. If the study findings hold up, they could serve as a guide to sift between the Red Planet's useful leads and its red herrings.

In a milestone discovery, astronomers have announced that the James Webb Space Telescope (JWST) has detected water ice drifting through a dusty ring of debris surrounding a distant, sunlike star.

Astronomers have long suspected that water, especially in its frozen form, might be common in the cold, outer reaches of planetary systems beyond our own. That's because in our own solar system, Saturn's moon Enceladus, Jupiter's Ganymede and Europa, and other icy moons are known to contain vast amounts of frozen water. Some of these moons are even thought to harbor subsurface oceans of liquid water, fueling ongoing discussions about their potential to support life.

Now, with JWST's confirmation last week, scientists say they can begin exploring how water — a key ingredient for life as we know it — is distributed and transported in other planetary systems.

The new discovery centers on a star called HD 181327, located about 155 light-years away, in the constellation Telescopium. At just 23 million years old, HD 181327 is a cosmic infant compared with our 4.6 billion-year-old sun, and it's encircled by a broad, dusty debris disk that is rich in small, early building blocks of planets.

"HD 181327 is a very active system," study co-author Christine Chen, a research scientist at Johns Hopkins University in Maryland, said in a NASA statement. Frequent collisions between icy bodies in this disk are constantly stirring up fine particles of dusty water ice, which are "perfectly sized for Webb to detect," Chen said.

The findings, published May 15 in the journal Nature, suggest these "dirty snowballs" of ice and dust could eventually play a key role in delivering water to future rocky planets that may form over the next few hundred million years. As planets take shape within the disk, comets and other icy bodies could collide with the young worlds and shower them with water — a process thought to have helped seed early Earth with the water that sustains life today.

Related: Did the James Webb telescope really find evidence of alien life? Here's the truth about exoplanet K2-18b.

JWST revealed that most of the distant star system's water ice is concentrated in the outer regions of the disk, where temperatures are cold enough for it to remain stable. Closer in, the ice becomes increasingly scarce, likely vaporized by the star's ultraviolet radiation or locked away in larger rocky bodies known as planetesimals, which remain invisible to JWST's infrared instruments.

According to the research team, the debris disk around HD 181327 resembles what the Kuiper Belt — the vast, doughnut-shaped region of icy bodies beyond Neptune — likely looked like billions of years ago during the early stages of our solar system's evolution.

"What's most striking is that this data looks similar to the telescope's other recent observations of Kuiper Belt objects in our own solar system," Chen said in the statement.

Everyone knows that your fingers get wrinkly after spending too long in the bath — but it turns out that those wrinkles form in the same way every time.

According to a new study published in May in the Journal of the Mechanical Behavior of Biomedical Materials, the exact pattern of the wrinkles on your fingertips — also known as their pruning — is unchanging .

The wrinkles were long thought to occur as a result of water entering the skin by osmosis and causing our fingertips to swell. However, researchers in the 1930s discovered that people with nerve damage in their fingers didn't form the wrinkles, suggesting that it wasn't the passive movement of water causing these patterns, but an active response of the body's sympathetic nervous system — an unconscious part of our nervous systems associated with the "fight or flight" response.

Subsequent research has found that the wrinkles form from the constriction of blood vessels below the skin's surface, as a result of water entering the fingers via sweat pores. As these blood vessels narrow, the skin's overall volume decreases, causing the skin to pucker, just like how a raisin forms from a dehydrated grape. If the nerves in the fingers are damaged, the blood vessels aren't instructed to constrict, and the fingers don't wrinkle.

However, it was unclear whether the wrinkle patterns appeared in the same place every time they formed. Study co-author Guy German, an associate professor of biomedical engineering at Binghamton University, said the question was initially posed to him by a student. "I thought: I haven’t the foggiest clue!” German said in a statement.

The researchers theorized that the wrinkles would form the same way each time, as the blood vessels that constrict to form them don't move around within the fingers.

Related: Why do wrinkles form?

"Blood vessels don’t change their position much — they move around a bit, but in relation to other blood vessels, they’re pretty static," German said. "That means the wrinkles should form in the same manner, and we proved that they do."

The researchers tested this hypothesis on three subjects, submerging their fingers in water for 30 minutes and taking pictures of their "pruning." They then repeated the process under the same conditions 24 hours later, and compared the images of their fingers.

The scientists discovered that each participant had the same patterns of wrinkles appear during both tests, indicating that an individual's wrinkles form the same way each time.

"This work conclusively reveals for the first time that topographical wrinkle patterns caused by prolonged human hand immersion in water are repeatable and consistent at different timepoints," the researchers wrote in the paper.

"The results demonstrate a significant relationship between wrinkle orientation across both time points and thus reveal the consistency of wrinkle morphology over time."

However, as the study only included a test group of three people, further research on more individuals needs to be done to firmly conclude that fingers prune the same way each time.

In fact, the exact reason that our fingers evolved to prune in water remains unclear. Several studies have found evidence suggesting that the wrinkles may improve our grip on objects during wet conditions. However, other research has found no improvement in grip or tactile acuity when fingers are wrinkled.

Regardless of its evolutionary origin, the researchers hope that their discovery of skin wrinkling being consistent each time could one day be used in forensic investigations.

"Biometrics and fingerprints are built into my brain," said German, whose father was a police officer. "I always think about this sort of stuff, because it’s fascinating."

"I feel like a kid in a candy store, because there’s so much science here that I don’t know."

The chemical composition of a meteorite could shake up scientists' understanding of how Earth got its water.

Researchers found signs of hydrogen sulfide in a type of meteorite similar to those that made up the early Earth. If these rocky bodies contain abundant hydrogen when out in space, it's possible that Earth could have formed with the materials to make water, rather than getting most of its water from chance collisions with asteroids and meteoroids throughout the planet’s early history. The findings were published April 16 in the journal Icarus.

Earth's chemical makeup is similar to waterless rocky bodies called enstatite chondrites, which suggests the planet may have formed from these types of materials. For years, scientists thought that meant that water had to come from objects in the outer solar system bombarding Earth. Those collisions are broadly unlikely because they depend on the specific geometry of our solar system, with Jupiter's gravity sending comets and meteorites toward the inner solar system, said Alessandro Morbidelli, who studies planet formation at Collége de France in Paris and was not involved in the new research.

But a 2020 study showed that, though enstatite chondrites don't contain water, they do contain hydrogen. In theory, then, the hydrogen they carried could have reacted with oxygen in the early Earth to form abundant water. But it wasn’t clear what form that hydrogen was in. Study coauthor James Bryson, a planetary scientist at the University of Oxford, and his colleagues suspected the hydrogen might be attached to sulfur inside the meteorites.

Using a technique known as X-ray absorption near-edge spectroscopy, the researchers looked for signs of hydrogen attached to sulfur inside an enstatite chondrite first found in Antarctica in 2012. They found more hydrogen than expected, in the form of hydrogen sulfide, throughout the fine-grained matrix of the meteorite.

Related: Meteorite found in a drawer at university contains 700-million-year-old evidence of water on Mars

The abundant hydrogen indicates that Earth could have contained hydrogen since the planet’s formation, Bryson wrote in an email to Live Science.

The findings suggest that rocky planets in the inner solar system — and potentially in other planetary systems — could form with much of the hydrogen necessary to create water oceans. "This means habitable conditions could be far more likely than we originally thought," Bryson continued.

Still, some scientists aren't convinced. Enstatite chondrites are prone to contamination from water already on Earth, said Conel Alexander, a meteoriticist at the Carnegie Institution for Science in Washington, D.C. who was not involved in the study. "When they enter the Earth's atmosphere and see water and even oxygen, they're going to start reacting quite quickly," Alexander told Live Science. The extra hydrogen might have come from the Antarctic ice and meltwater around the meteorite before it was discovered, Alexander said.

Though the researchers took steps to avoid examining areas that had visibly reacted with water, a fresh enstatite chondrite could confirm where the hydrogen came from once and for all. "The perfect thing would be for a sample of an enstatite chondrite to fall to Earth, and we scoop it up immediately and stick it into a water-free, oxygen-free environment and keep it there," Alexander told Live Science.

Microplastic pollution from industrial waste has been contaminating freshwater ecosystems for decades, with evidence pointing to this run-off starting in the 1950s to 1970s. Now, though, new evidence suggests the extent of that pollution might be even broader than once thought.

In a study published April 25 in the journal Science of The Total Environment, scientists examined the larvae of caddisflies, small insects that build protective casings around themselves using plant material, sand and small stones in their environment. These casings, gathered in the 1970s and 1980s, came from clear, spring-fed streams in the Netherlands that were considered pristine at the time.

However, the study revealed that the larvae were incorporating plastic particles into their protective casings as early as 1971 — in other words, microplastics had infiltrated even these seemingly untouched ecosystems.

"The inclusion of plastic in the casing of a caddisfly means plastic is entering the food chain," said lead study author Auke-Florian Hiemstra, a doctoral candidate in evolutionary ecology at the Naturalis Biodiversity Center.

"Many birds and fish eat these caddisfly larvae, and some swallow them including their casing," Hiemstra told Live Science in an email. "If caddisflies have been affected by microplastics for over half a century, that means the broader ecosystem is affected too."

Related: Recycled black plastic can contain flame retardants, viral study found. That's still true — but their math was off

The casing specimens in the study are part of the natural history collections at the Naturalis Biodiversity Center in the Netherlands. The researchers used a technique called energy dispersive X-ray analysis to reveal chemical elements and additives commonly associated with plastics inside the casings.

This provided a rare snapshot into the impact of microplastics on freshwater systems, which represent less than 4% of current studies on microplastics, Hiemstra said. Generally, the presence of microplastics in the 2000s is well documented, but the historical timeline of microplastic pollution has remained vague. This lack of historical data has made it difficult to assess how long ecosystems and human populations have been exposed to microplastics, thus complicating risk assessments and epidemiological studies.

So, how might this study change our understanding of the history of microplastic exposure and its potential impacts on human health?

Microplastics in nature and the body

Microplastics are tiny fragments of synthetic polymers that can take anywhere from hundreds to thousands of years to degrade. They're defined as being between 1 micrometer and 5 millimeters long. Today, they seem to be found virtually everywhere: in clouds, the air we breathe, food, drinking water, and human blood and breast milk. These particles stem from the breakdown of larger plastics, and in some cases, they are intentionally manufactured for use in certain cosmetics and cleaning products.

Research suggests that the human body clears out some larger microplastics measuring up to 150 micrometers long, while fragments smaller than 10 micrometers may be absorbed into tissues. But recent research suggests that some plastics in our bodies are even tinier than that.

While what qualifies as "nanoplastic" is still under debate, these ultrasmall particles are typically considered to be any plastic fragments smaller than 1 micrometer (or 1,000 nanometers) in diameter. A human hair, by comparison, is around 80,000 nanometers wide. Nanoplastics are small enough to potentially pass through cell membranes, studies suggest.

Matthew Campen, a toxicologist at the University of New Mexico, recently led a study that pointed to the presence of nanoplastics in human tissues. Using advanced, high-resolution imaging techniques, his team identified plastic fragments measuring no more than 200 nanometers in length — thin enough that they were translucent — in brain tissue from a few dozen organ donors.

After its publication, some of the analytical techniques used in the study were criticized, so the exact quantities of different types of plastic may be off, experts told Live Science. But by detecting nanoplastics, the findings expand upon previous work that relied on microscopes that could only detect particles up to 25 times larger.

That study, which included samples collected between 2016 and 2024, also suggested that later samples carried higher concentrations of plastics, and that the brains of individuals who died with dementia contained more plastic than healthy brains. These results raised questions about whether the public's plastic exposure has been increasing over time.

Hiemstra's new findings feed into that broader discussion and may have implications for how we understand the health risks of microplastics. If the pollutants have been present throughout the environment — not only near industrial sites — since the 1970s, that might reframe our understanding of where people have been exposed and for how long. Plastics not only accumulate in the environment, but also in the body, so better understanding the timeline and extent of exposure can help scientists unpack its long-term health outcomes.

As Hiemstra's study was focused on only the Netherlands, though, other work will need to be done to understand the history of microplastic pollution on a global scale.

Related: 'Very concerning': Microplastics can accumulate in cancer cells and may help them spread, study hints

What do microplastics do to our bodies?

Scientists are still working to understand exactly how microplastics and the chemicals within plastics — such as phthalates and per- and polyfluoroalkyl substances (PFAS) — might affect our bodies, Tracey Woodruff, a professor at the University of California, San Francisco (UCSF) who studies how pollutants affect reproductive and developmental health, told Live Science.

Early research has linked plastic exposure to the risk of various health conditions, including heart disease, lung disorders, cancer and Alzheimer's disease. In each of these cases, the link is correlative, so it's not clear if or how the plastics might be contributing to the diseases. In addition, in lab-dish studies, some types of plastics appear to be relatively harmless, while others have been shown to kill human cells in vitro.

In 2024, Woodruff and her team at UCSF's Program on Reproductive Health and the Environment published a systematic review of nearly 2,000 studies on the health effects of microplastics as part of a California state-commissioned report aimed at guiding policy decisions. The review identified potential health effects on respiratory, digestive and reproductive health, and particularly on sperm.

"While a link between chemicals in plastics and chronic diseases is clear, it's hard to separate the effects of the microplastic from its chemical additives," Woodruff noted.

She added that, "with rising cancer rates among younger people and increasing exposure [to microplastics] from early life, the potential long-term health risks — especially for those exposed in utero — remain a major concern," Woodruff said. Exposure to pollution is one of several competing theories for why the rates of certain cancers are rising in people under 50.

"More data will help address the uncertainty in the findings, but we're being exposed to [microplastics] right now, so it would be prudent to reduce exposures," Woodruff said.

While it's suspected that microplastics have negative impacts on human health, the World Health Organization emphasizes that the evidence for these effects is still limited and inconclusive.

"Our understanding of the potential harms of microplastic exposure is very preliminary at this stage," said Bernardo Lemos, a professor of pharmacology and toxicology at the University of Arizona and an adjunct professor of environmental epigenetics at the Harvard T.H. Chan School of Public Health. Lemos has led research to document the effects of microplastic exposure in humans and in model organisms, such as fruit flies, mice and fish.

"I am sure there will be many more studies documenting an abundance of microplastics in historical samples," Lemos told Live Science in an email. "It will be interesting to document how microplastics' abundance and quality change over decades." The Organisation for Economic Co-operation and Development, an intergovernmental organization, predicts that plastic production may triple by 2060.

Related: Humans inhale a staggering amount of microplastic every week. Here's where it ends up

Is it possible to avoid microplastics?

While Woodruff noted it would be prudent to reduce microplastic exposure, it's unclear what levels of micro- and nanoplastics we're realistically taking in on a daily basis. "Plastics can degrade into smaller fragments, but they persist, so we're going to be exposed to them for a very long time," Woodruff said.

She suggested that, at the individual level, people can reduce their exposure to microplastics and the chemicals in them by consuming fewer ultraprocessed foods, which are more likely to come into contact with plastic than whole or less-processed foods. She also suggested that it may help to avoid plastic containers, bottles and packaging where possible.

"There is still so little known about the history of microplastics," Hiemstra said. But thanks to collections that include specimens like the caddisfly casings, we may have unknowingly collected more evidence than we thought about the early days of this pollutant.

Other natural history collections around the world may harbor even older casings with microplastics, he suggested, highlighting the untapped value of such collections as tools for environmental science. They may offer a way to establish historical baselines of microplastic pollution, which are still largely missing from the record and could help us trace the true health impact of plastics.

This article is for informational purposes only and is not meant to offer medical advice.

Researchers have discovered a "shape-recovering liquid" that appears to defy the laws of thermodynamics. The liquid, which is made up of oil, water and magnetized particles, consistently separates into a form resembling a Grecian urn.

This discovery began when Anthony Raykh, a polymer science and engineering graduate student at the University of Massachusetts Amherst, was studying a mixture of oil, water and nickel particles in a vial. He shook the vial to create an emulsion — or a blend of liquids that don't mix. But instead of separating into a clear top and bottom, the mixture formed the shape of a Grecian urn. Even after shaking the vial over and over, it kept returning to this shape.

"That's really odd," study co-author Thomas Russell, a professor of polymer science and engineering at University of Massachusetts Amherst, told Live Science. It's strange, he explained, because typically when a mixture of liquids that don't blend return to equilibrium before emulsion, they want to minimize the interfacial area, or the boundary between the two liquids. This tendency to minimize the interfacial area is governed by the laws of thermodynamics, which describe how temperature, heat, work and energy are related in physical systems.

In typical emulsions of oil and water, the liquids form spherical droplets, which have minimal surface area. In comparison, the Grecian urn shape has a higher surface area. This higher surface area, which seems to contradict the laws of nature, puzzled the researchers.

After investigating this odd behavior, they found that interactions between the nickel particles "sort of took over" to create what appeared to be a violation of the laws of thermodynamics, Russell said. The particles created magnetic dipoles, a phenomenon where their magnetic poles attract each other, creating a field of "chains" on the liquid's surface. This interaction interferes with how the emulsion separates.

While Russell said researchers have previously examined the segregation of particles in oil-water mixtures — as Raykh had been doing — nobody else had conducted the same experiment. So, no other researchers had observed or reported the higher interfacial energy seen with the Grecian urn shape.

While at first glance this mixture seems to defy the laws of thermodynamics, Russell clarified that it's just a strange case of them. The scientists realized that the particles' magnetic interference played a role, as its influence created a higher interfacial energy, which resulted in the higher surface area-shape. And in general, the laws of thermodynamics apply to systems overall, not to the interactions between individual particles, Russell said.

The researchers published their findings on April 4 in the journal Nature Physics.

Just like the mountains, lakes on Earth can be ancient, or more than 1 million years old. There are only 20 ancient lakes on the planet, but which is the oldest?

Earth's oldest lake has a clear winner: Lake Baikal in southeast Siberia. Scientists estimate that this enormous freshwater body is 25 million years old, according to Ted Ozersky, an associate professor of biological limnology (the study of inland bodies of water) at the University of Minnesota. By contrast, the Great Lakes formed less than 20,000 years ago. The second oldest lake on Earth is Lake Issyk-Kul in Kyrgyzstan, which formed about 20 million years ago.

Lake Baikal measures 12,239 square miles (31,700 square kilometers), making it Earth's seventh-largest lake. It is not only the world's oldest lake but also the deepest one, at about 1 mile (1.6 kilometers). But that's just the water depth. "The actual basin is much more than a mile deep," Ozersky told Live Science, including between 3.1 and 4.3 miles (5 to 7 km) of sediment at the bottom. In the case of Lake Baikal, where there are miles of sediment, researchers use seismic surveys to estimate the average rate of sediment formation, Ozersky said.

This sediment is key to dating the lake. Researchers measure a lake's age through isotopic dating. This technique involves measuring the ratios of radioactive isotopes. In this case, limnologists analyze lake sediments for radioactive versions of cesium, lead and carbon. This analysis tells them how old the different layers of sediment are and how fast that sediment accumulates, Ozersky explained

Related: How much water is in Earth's crust?

By understanding lake formation — and Lake Baikal's formation, in particular — researchers can get a better idea of how it has persisted for millions of years. Many lakes form as glacial features, Mark Edlund, a senior scientist and the director of aquatic research and collections at the Science Museum of Minnesota, told Live Science. Glaciers score a pocket in the landscape and deposit chunks of ice that eventually melt and fill the depression. "But in the grand scheme, they're very short-lived systems," Edlund said.

On the other hand, Lake Baikal is a rift lake. Rift lakes form when two continental plates start moving away from each other, creating a chasm. This chasm is called a graben. As these plates continue to drift apart, the graben continues to deepen. "As a result, that site never fills in," Edlund said, which is why rift lakes can last so long.

In fact, Ozersky said Lake Baikal gets an inch (2.5 centimeters) wider every year. Some of the world's other oldest lakes, like Lake Malawi (up to 5 million years old) and Lake Tanganyika (up to 12 million years old) — both in Southeast Africa — also come from rifts.

Lake Baikal also claims the title of Earth's most biologically diverse lake, according to Ozersky.

"Evolution has had so much time to work in that system without being interrupted," he said. It also has the highest rate of flora and fauna endemic to its ecosystem, meaning those plants and animals aren't found anywhere else on Earth. Perhaps the best and most beloved example is the Baikal seal (Pusa sibirica), the only freshwater seal species. (Although other seal species may inhabit lakes, those seals have "invaded" them through streams, Ozersky noted.)

This ancient lake also hosts hundreds of species of freshwater shrimp, which gives researchers the opportunity to study speciation and diversification. "Trying to understand how evolution works is one thing that is really interesting about Baikal," Ozersky said.

Edlund also studies diatoms, which are a unicellular type of algae. These organisms pull dissolved silica from the water and turn it into biologically produced glass, which encases them. Diatoms are typically between 10 and 50 microns (about half the width of a human hair) in diameter, but Baikal's diatoms are unusually large at about 50 to 150 microns. "When we look at the diatoms in Lake Baikal, they just blow your mind," Edlund said.

The lake is also open to human visitors. But because it's covered with ice five months out of the year, it's not a great swimming destination. Its average surface temperature is 39 degrees Fahrenheit (4 degrees Celsius). "It's a bitterly cold lake," Edlund said. "If you want to swim in it, you've got to gird your loins."

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

Water may have emerged in the universe far earlier than scientists thought — and it could mean that life could be billions of years older too, new research suggests.

Water is one of the most essential ingredients for life as we know it. But exactly when water first appeared has been a question of scientific interest for decades.

Now, new research suggests that water likely existed 100 million to 200 million years after the Big Bang — billions of years earlier than scientists previously predicted. The research was published March 3 in the journal Nature Astronomy.

The early universe was dry because it was mainly filled with very simple elements, like hydrogen, helium and lithium. Heavier elements didn't develop until the first stars formed, burnt through their fuel supplies and ultimately exploded. Such stellar explosions, known as supernovas, acted like pressure cookers that combined lighter elements into increasingly heavier ones.

"Oxygen, forged in the hearts of these supernovae, combined with hydrogen to form water, paving the way for the creation of the essential elements needed for life," study co-author Daniel Whalen, an astrophysicist at the University of Portsmouth in the U.K., said in a statement.

Related: 32 strange places scientists are looking for aliens

To determine when water first appeared, the researchers examined the most ancient supernovas, called Population III supernovas. Whalen and his team looked at models of two types of these early star remnants: core-collapse supernovas, when a large star collapses under its own mass; and pair-instability supernovas, when a star's interior pressure suddenly drops, causing a partial collapse.

The researchers found that shortly after the Big Bang, both supernova types produced dense clumps of gas that likely contained water.

Overall, the amount of water in these gas clouds was probably pretty small — but it was concentrated in the areas where planets and stars were most likely to form, the team found. The earliest galaxies probably arose from these regions, which means that water may have already been in the mix when they formed.

"This implies the conditions necessary for the formation of life were in place way earlier than we ever imagined — it's a significant step forward in our understanding of the early Universe," Whalen said.

Observations from the James Webb Space Telescope, which is designed to view the universe's oldest stars, may help further validate these results.

For the first time, scientists have observed water molecules splitting in real time to form hydrogen and oxygen.

And right before they split, the molecules did something completely unexpected: They flipped 180 degrees.

This micro acrobatic stunt takes energy, which offers a crucial explanation for why splitting water takes more energy than theoretical calculations suggested.

The researchers say that studying this further could offer key insights into making the process of splitting water molecules more efficient — opening a pathway to cheaper clean hydrogen fuel and breathable oxygen for future Mars missions. They published their findings March 5 in the journal Science Advances.

Making hydrogen fuel

Hydrogen has a number of key properties that make it an enticing source of green energy. The energy-rich fuel is capable of powering trucks and even cargo ships, and it is the only alternative to fossil fuels in industries such as steel and fertilizer manufacturing. When it's burned, the fuel releases water instead of carbon dioxide.

Yet the steep energy requirements for hydrogen production severely limit the scale at which the fuel is produced. According to the International Energy Authority, 322 million tonnes (354 million tons) of hydrogen fuel needs to be produced each year to meet global energy needs. But in 2023, only 97 million tonnes (107 million tons) was manufactured at a monetary cost 1.5 to six times greater than fossil fuel production — and the vast majority of it was made using fossil fuels too.

Related: Scientists discover revolutionary method that makes fuel from water and sunlight — but it's not finished yet

Hydrogen fuel is made by adding water to an electrode and then splitting the water with an applied voltage into hydrogen and oxygen.

This process is most efficient when the chemical element iridium is used as a catalyst for the oxygen evolution reaction that cleaves oxygen from water molecules. But iridium only arrives on our planet from meteorite impacts, making it costly and scarce.

But even when using iridium, the process is less efficient than scientists believe it should be.

"It ends up taking more energy than theoretically calculated. If you do the math, it should require 1.23 volts. But, in reality, it requires more like 1.5 or 1.6 volts," study lead author Franz Geiger, a professor of chemistry at Northwestern University, said in a statement. "Providing that extra voltage costs money, and that's why water splitting hasn't been implemented at a large scale."

To better understand the energy requirements of this process and why it's less efficient than theory suggests, the researchers placed water on an electrode inside a container and measured the molecules' positions using the amplitude and phase of laser light shone onto them.

When the scientists applied a voltage across the electrode, they observed that the molecules rapidly flipped and rotated so that their two hydrogen atoms touching the electrode faced up and the oxygen atom faced down.

"Electrodes are negatively charged, so the water molecule wants to put its positively charged hydrogen atoms toward the electrode's surface," Geiger said. "In that position, electron transfer from water's oxygen atom to the electrode's active site is blocked. When the electric field becomes strong enough, it causes the molecules to flip, so the oxygen atoms point toward the electrode's surface. Then, the hydrogen atoms are out of the way, and the electrons can move from water's oxygen to the electrode."

By measuring the number of molecules that rotated and the energy required for them to do so, the researchers found that this flipping was likely a necessary and unavoidable part of the splitting process. What's more, the researchers discovered that higher pH levels made this process more efficient.

Further studying this process could help scientists to design more efficient catalysts to use in the process, and to better understand the chemical processes involved, the researchers said, while also offering fresh insights into how water behaves.

"Our work underscores how little we know about water at interfaces," Geiger said. "Water is tricky, and our new technology could help us understand it a bit better."

"By designing new catalysts that make water flipping easier, we could make water splitting more practical and cost-effective," he added.

Scientists have discovered evidence that liquid water was once exposed to the air in ancient, shallow lakes on Mars. The finding is evidence that not all water on the Red Planet was covered in ice, as some Martian climate models suggest.

Planetary geologists and astronomers studying Mars have known for decades that water was once likely present on the planet, after NASA's Mariner 9 mission captured images of dry gullies in the 1970s. But there has been ongoing debate about what form that water took and how long it lasted. Some models predict that any liquid water on Mars' surface must have been covered by sheets of ice before it disappeared.

However, the new findings, which were published Jan. 15 in the journal Science Advances,, tell a different story. The patterns, which were photographed by NASA's Curiosity rover, are known as wave ripples — minute ridge-like structures that form along the shores of lakebeds. This means that exposed liquid water must have flowed across Mars' surface at some point in its history. The ripples were present in two separate lakebeds in Gale Crater, which Curiosity has been exploring since Aug. 2012.

"The shape of the ripples could only have been formed under water that was open to the atmosphere and acted upon by wind," study first author Claire Mondro, a sedimentologist at CalTech, said in a statement.

Related: 32 things on Mars that look like they shouldn't be there

Hope for life?

The researchers also analyzed the height and spacing of the ripple waves to determine the size of the lake that formed them. The structures are approximately 0.2 inches (6 millimeters) tall and about 1.6 to 2 inches (4 to 5 centimeters) apart, indicating they were left by small waves. Based on these dimensions, the researchers believe the Martian lake must have been less than 2 meters (6.5 feet) deep.

Both dry lakebeds appear to have formed around 3.7 billion years ago, indicating that Mars had an atmosphere dense and warm enough to support liquid water for longer than previously thought — which could have intriguing implications. "Extending the length of time that liquid water was present extends the possibilities for microbial habitability later into Mars's history," Mondro said. In other words: living organisms may have had a longer window in which they could have evolved on the Red Planet.

Most of Mars' atmosphere and surface water were later stripped away over billions of years. Scientists believe this occurred because the planet lost its magnetic field, leaving it vulnerable to solar radiation. As the powerful solar wind bombarded the Martian atmosphere, most of the planet's carbon dioxide and water evaporated into space, leaving behind the frigid desert we know today.

Mars quiz: Is your knowledge of the Red Planet out of this world?

An extensive model of the Antarctic ice sheet is helping researchers peer deep beneath the ice to reveal the continent's hidden plumbing.

Scientists used computer models to predict how water flows under the entire Antarctic ice sheet, which dictates where and how quickly glaciers move toward the ocean. The findings, published Dec. 29, 2024 in the journal Geophysical Research Letters, will improve predictions of ice sheet stability and future sea level rise.

Current models predict that ice melt from Antarctica could raise sea levels up to 12 inches (30 centimeters) by 2100. Some of this melt comes from ice sliding from the continent's bedrock into the ocean. Liquid water beneath the ice sheet can lubricate the ice, similar to sliding a glass across a wet countertop.

But the extent of this lubrication isn't uniform across the ice sheet — it depends on the weight of the ice and the depth and pressure of the water beneath it. Understanding how these factors vary is important for accurately predicting how much ice will flow into the ocean, and how quickly it will move. While models of smaller individual areas account for the effects of water at the base of the ice sheet, the new study is the first to incorporate it for the whole continent.

Related: Never-before-seen shapes up to 1,300 feet long discovered beneath Antarctic ice

To simulate how subglacial water affects glacier motion, the researchers combined two existing models: the Glacier Drainage System Model, which simulates the way water flows under ice sheets; and the Ice-sheet and Sea-level System Model, which predicts how the ice sheet will flow and change in response to various factors, such as temperature.

The combined model "allows us to identify where water is underneath the ice, or model where the water would be underneath the ice, where it's particularly thick and the pressures are high enough to enable the ice to slide and to flow faster," Neil Ross, a geophysicist at Newcastle University in the U.K. who was not involved in the new study, told Live Science.

The researchers modeled the effective pressure at the base of the ice — the difference between the weight of the ice and the water pressure beneath it. "As that approaches zero, we're approaching the situation where the ice is basically free, floating on the base of water," Rupert Gladstone, a computational glaciologist at the University of Lapland in Finland who was not involved in the research, told Live Science.

The model revealed that the lowest effective pressures are in the interior of the continent and beneath outlet glaciers along the edge of the ice sheet, meaning the ice flows fastest in these regions. Meanwhile, floating ice shelves around the edge of the continent slow ice flow into the ocean. If these ice shelves melt, more ice could flow from the bedrock into the ocean and contribute to sea level rise, the authors wrote.

The model also accurately predicted the locations of known subglacial lakes in western Antarctica. In addition, it predicted the locations of large channels beneath the ice where subglacial water flows into the ocean. Many of these locations align with areas of the ice shelf that are known to melt quickly, suggesting that fresh water entering the ocean from these channels impacts melt rates.

Further studies in Antarctica could look for these features in areas predicted by the model. "It's enabled us to identify where future field observations might be required," Ross said. Field studies could help refine the model and help scientists better understand how subglacial water affects ice flow, Ross added.

Test your knowledge of Antarctica

Drinking alkaline water has become a popular trend, with many companies claiming it offers a variety of benefits, from improved hydration to chronic disease prevention.

But what is alkaline water, and does it actually have any benefits?

"The claims are not justifiable," Salome Kruger, a professor of nutrition at the Centre of Excellence for Nutrition at North-West University at Potchefstroom in South Africa, told Live Science.

Substances that are alkaline are basic, or the opposite of acidic — they have a high pH, while acids have a low pH. Lower pH levels reflect a higher quantity of positively charged particles. Alkaline water usually has a pH level between 8 and 9, higher than that of regular drinking water, which is typically "neutral" at around 7.

Water can become alkaline when it flows over rocks and picks up alkaline minerals, or it can be produced artificially through electrolysis — a process in which filtered water passes through a device that separates the water into alkaline and acidic streams. The alkaline stream contains minerals like calcium, magnesium and potassium.

Related: Why does drinking water feel so good when you're thirsty?

When consumed, it's unlikely alkaline water has any long-lived impacts on the body. That's because the moment it comes in contact with the stomach, its pH is neutralized by the acidity of the gastric juices — which has a pH of 1.5 to 3.5.

The bicarbonate in the water reacts with gastric acid to form water and carbon dioxide, which is then burped out. The minerals in the water are absorbed in the small intestine and enter the bloodstream, where pH is tightly maintained between 7.35 and 7.45 thanks to the lungs and kidneys. Excess minerals in the blood are filtered out by the kidneys and excreted.

Thus, drinking alkaline water is unlikely to significantly "alkalize" the body. What's more, scientific studies on possible health effects of alkaline water are limited and often inconclusive, Kruger said.

Test-tube studies suggest that alkaline water can inactivate human pepsin, a digestive enzyme. In acid reflux, pepsin reaches the throat and damages tissue, so in that context, inactivating pepsin might sound beneficial. But in the stomach, this could potentially disrupt digestion, which would be undesirable, Kruger explained.

Animal research has shown potential benefits, such as increased life span and weight loss, in animals that consumed alkaline water for long periods of time. But researchers could not explain the mechanisms behind these effects, so it's unclear if they're applicable to humans.

One observational study of over 300 women found that those who regularly drank alkaline water had lower body mass indexes (BMIs), blood sugar levels and blood pressure than those who drank normal water. But the former group also had higher incomes, better nutrition and more physical activity. "These lifestyle factors are known to have a much stronger impact on chronic disease risk than simply drinking alkaline water," Kruger said.

There is also no conclusive evidence that alkaline water hydrates better than regular water. In a 2016 study, researchers saw a reduction in blood viscosity — the thickness and stickiness of blood — in people consuming alkaline water and suggested this may reflect better hydration. However, other studies that tracked direct markers of hydration did not find any significant differences between alkaline and regular water.

Related: Boiling tap water can remove 90% of microplastics

Broadly, methodological issues in some of these human studies, such as small sample sizes and a lack of baseline measurements, make it difficult to draw firm conclusions, said Lize Havemann-Nel, an associate professor at the Centre of Excellence for Nutrition at North-West University at Potchefstroom in South Africa.

There is some emerging research that hints alkaline water may act as an antioxidant, reducing oxidative stress and muscle damage from high-intensity or long-duration exercise. But she cautioned that this work is still in the early stages. If alkaline water does have any benefits, these may be more related to its electrolyte content than its pH, Havemann-Nel suggested.

Taken together, the available evidence suggests alkaline water has few, if any, clear benefits over regular water — and drinking it can carry some risks, Kruger said.

For instance, drinking water with a pH above 9 might pose risks for people taking drugs that block stomach-acid production, such as proton pump inhibitors, because it can further raise the stomach's pH levels. Plus, excess minerals from alkaline water could disrupt mineral levels in the blood of people with kidney disease, who can't effectively filter the minerals out.

If an alkaline-water product contains sodium bicarbonate, as some do, it could also contribute to excessive sodium intake. "Many people already consume high sodium levels from table salt and processed foods, so additional sodium from alkaline water might exacerbate this issue," Kruger said.

This article is for informational purposes only and is not meant to offer medical advice.

When the cosmos' first stars exploded in spectacular supernovas, they may have unleashed enormous amounts of water that flooded the early universe — and potentially made life possible just millions of years after the Big Bang, new simulations suggest.

However, this theory clashes with our current understanding of cosmic evolution and will be extremely difficult to prove.

Water is one of the most abundant compounds in the universe, according to NASA. Aside from Earth, astronomers have found water in several places throughout the solar system, including scattered above and below the surface of Mars, inside the ice caps of Mercury, surrounding the shells of comets and buried in underground oceans on several major moons. Outside our cosmic neighborhood, researchers have also detected water on distant exoplanets and within massive clouds of interstellar gas that permeate the Milky Way.

Until now, scientists assumed that all this water gradually built up over billions of years as hydrogen, the most abundant element in the universe, combined with oxygen that has been forged in the hearts of stars and expelled via supernovas. But in the new study, uploaded Jan. 9 to the preprint server arXiv, researchers simulated the explosive deaths of giant, short-lived early stars — which each had a mass equivalent to around 200 suns — and found that they could create the conditions needed for water to take shape.

The water from these stellar explosions would likely have formed at the hearts of dense clouds of hydrogen, oxygen and other elements left behind by stars. It may have had concentrations up to 30 times higher than the water seen floating in interstellar space within the Milky Way, the researchers wrote in the study, which has not been peer-reviewed yet.

Related: Could a supernova ever destroy Earth?

If correct, the new findings would have big implications for scientists' understanding of galaxy evolution and extraterrestrial life.

"Besides revealing that a primary ingredient for life was already in place in the universe between 100 million and 200 million years after the Big Bang, our simulations show that water was likely a key constituent of the first galaxies," the researchers wrote.

Early cosmic uncertainty

One of the biggest issues with the new study is that scientists have never directly observed one of the early stars that the researchers are modeling, known as population III stars. Instead, researchers have only indirectly observed a few of these stellar trailblazers by analyzing the stars that were birthed from their remains, so it's still not certain what they were really like.

If there was abundant water in the early universe, it would also suggest that the cosmos should have accumulated much more water than we currently see in our surroundings.

One explanation for this that has been posited by other scientists is that the universe underwent a drying-out period during which large quantities of water were lost, according to Universe Today. However, it is unclear what the cause of this event could have been.

"There is also the fact that while water formed early, ionization and other astrophysical processes may have broken up many of these molecules," Universe Today reported, meaning that the water from the first supernovas may have been short-lived.

Although water is a key ingredient for life on Earth, there is also no guarantee that its presence in the early universe would have made extraterrestrial life more likely.

Dry conditions across Southern California set the stage for a series of deadly wind-driven wildfires that burned thousands of homes and other structures in the Los Angeles area in early January 2025.

Ming Pan, a hydrologist at the University of California-San Diego's Center for Western Weather and Water Extremes, tracks the state's water supplies. He put Southern California's dryness into perspective using charts and maps.

How dry is Southern California right now?

In early January, the soil moisture in much of Southern California was in the bottom 2% of historical records for that day in the region. That's extremely low.

Hydrologists in California watch the sky very closely starting in October, when California's water year begins.

The state gets very little rain from May through September, so late fall and winter are crucial to fill reservoirs and to build up the snowpack to provide water. California relies on the Sierra snowpack for about one-third of its freshwater supply.

However, Southern California started out the 2024-25 water year pretty dry. The region got some rain from an atmospheric river in November, but not much. After that, most of the atmospheric rivers that hit the West Coast from October into January veered northward into Washington, Oregon and Northern California instead.

When the air is warm and dry, transpiration and evaporation also suck water out of the plants and soil. That leaves dry vegetation that can provide fuel for flying embers to spread wildfires, as the Los Angeles area saw in early January.

Related: Santa Ana winds: What is causing the deadly fires sweeping across Los Angeles?

So, while Northern California's water and snowpack conditions are in good shape, Southern California is much drier and its water storage is not doing so well.

The Southern Sierra snowpack was starting to dip below normal in early January.

What can California expect for the rest of 2025?

The U.S. Climate Prediction Center's seasonal outlook through March suggests that drought is likely to develop in the region in the coming months.

The outlook takes into account forecasts for La Niña, an ocean temperature pattern that was on its way to developing in the Pacific Ocean in early 2025. La Niña tends to mean drier conditions in Southern California. However, not every La Niña affects California in the same way.

One or two big rain events could completely turn the table for Southern California's water situation. In 2023, California saw atmospheric rivers in April.

So, it's hard to say this early in the season how dry Southern California will be in the coming months, but it's clear that people in dry areas need to pay attention to the risks.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

It's a story all too many people know: You wake up with a stomachache and soon find yourself stuck in the bathroom, battling nausea, stomach cramps, vomiting and diarrhea. Within a day or two, everyone in the house is showing the same symptoms. These fast-spreading bouts of gastrointestinal distress are often caused by norovirus, colloquially known as the "stomach bug" or "stomach flu."

Norovirus is highly contagious and the leading cause of foodborne illness in the United States, according to the Centers for Disease Control and Prevention (CDC). The virus spreads easily through direct contact with an infected person or with contaminated surfaces, even after the infected person's symptoms have passed. Though cases tend to rise in fall and winter when people gather indoors in close quarters, anyone can contract norovirus at any time of the year.

Neutralizing, or "killing," any norovirus that ends up on people's hands or on surfaces helps to curb the spread of the illness. So what's the best way to kill norovirus?

Washing your hands with soap and water is the best way to get rid of the virus, Dr. Robert Hopkins Jr., medical director of the National Foundation for Infectious Diseases, told Live Science. Cleaning hard surfaces, such as countertops, with bleach-based solutions can also neutralize the virus and thus prevent it from spreading to others.

Related: Here's the best way to protect yourself from a norovirus outbreak

However, one common cleanser doesn't work against norovirus: alcohol-based hand sanitizer. That's because alcohol-based cleansers are only effective against certain types of viruses, known as "enveloped" viruses.

All viruses contain genetic material — namely, DNA or RNA — wrapped in a protein coating called a capsid. Some viruses, such as the culprits behind influenza and COVID-19, also have a protective outer "envelope" called a phospholipid bilayer, which is similar to the membrane that surrounds human cells. Without this envelope, these viruses can't attach to or infect host cells. Alcohol-based cleansers neutralize viruses by interfering with that outer envelope, rendering the virus inert.

But alcohol-based hand sanitizers, cleaners and cleansing wipes don't work against non-enveloped viruses, such as norovirus. Non-enveloped viruses don't have or need a phospholipid bilayer, and they can survive much longer on surfaces without invading a host cell. (Norovirus can survive for days or weeks on surfaces, depending on the surface type.)

Alcohols can't break through the protein capsid of these viruses as easily as they do phospholipid bilayers, so neutralizing non-enveloped viruses requires different cleansers, such as soap or bleach.

As a person washes their hands, the soap surrounds the viral particles and physically washes them off the skin. "Soap itself is very effective at disrupting capsules of almost any type of cell. If you put enough soap on your skin, you're going to break the skin barrier. Same with bleach,” Hopkins said. That's why frequent handwashing can sometimes lead to dry skin.

Cleaning surfaces requires an even stronger cleanser, such as bleach, to completely inactivate the virus.

Once someone contracts norovirus, they have to let the infection run its course — there are no available antiviral treatments for it, and antibiotics won't help because they treat bacterial infections, not viral ones. The CDC recommends that people who catch the stomach bug drink plenty of fluids to prevent dehydration and stay away from others while they're sick, as well as for two days after their symptoms resolve.

"When we don't have specific antivirals, then I think it's even more important that we do what we can to prevent infections, rather than having to treat those symptoms," Hopkins told Live Science.

To protect yourself and others from norovirus, the CDC recommends frequent handwashing with soap and water, especially after using the bathroom, before preparing or handling food, and before and after caring for someone who is sick. If a family member or roommate falls ill, disinfect contaminated surfaces with a bleach solution and wash soiled clothing in hot water. The CDC has a video detailing how to do this correctly.

There's evidence that norovirus particles may possibly spread through the air in health-care settings, and that vomiting can produce airborne particles. So in conjunction with handwashing and disinfecting measures, wearing a face mask may also help to reduce transmission, as suggested in a 2022 study in the journal Emerging Infectious Diseases.

"If you are sick, whatever your symptoms are, stay away from others," Hopkins said. "You don't want to transmit what you have, whatever it may be."

Editor's note: This article was updated on Jan. 14, 2025, to clarify that the final study mentioned was published in a CDC journal but not conducted by CDC scientists.

This article is for informational purposes only and is not meant to offer medical advice.

More than 200 million people in the United States live in areas where fluoride is added to tap water. According to the most recent data available, 24 other countries around the world — including the United Kingdom, Brazil and Canada — add fluoride to their drinking water supplies, and many other jurisdictions end up ingesting fluoride via naturally occurring deposits in their water sources.

Water fluoridation has been lauded as one of the top public health achievements of the 20th century by the U.S. Centers for Disease Control and Prevention (CDC). But the practice has long been controversial, with vocal opponents arguing that the water fluoridation has adverse health or cognitive impacts.

So why do we add fluoride to water in the first place? And what do we know about its safety?

How water fluoridation began

The history of water fluoridation begins in the early 20th century, when a young dentist named Dr. Frederick McKay noticed a strange phenomenon in Colorado Springs. Residents of the town had distinctive brown, mottled stains on their teeth. Further observation revealed that, despite these notable stains, people with the "Colorado brown stain" seemed to have teeth that were unusually resistant to decay. Tooth decay, also called caries or cavities, causes holes to form in teeth.

Researchers traced the cause of the stain to the town's water supply, which contained abnormally high levels of fluoride. This finding prompted dentists to investigate whether it was possible to reap the beneficial, tooth-protecting effects of fluoridated water without experiencing the downsides of staining your teeth.

In 1945, Grand Rapids, Michigan, became the first city in the world to approve a pilot water fluoridation program. Researchers added a small amount of fluoride to the city's water supply and measured rates of tooth decay in the town's nearly 30,000 schoolchildren over the next decade. Their findings revealed that children who were born after water fluoridation began had more than 60% fewer cavities than those born prior to the program.

Related: How does fluoride prevent cavities?

The benefits of fluoridated water

Since 1945, water fluoridation has proliferated as a widespread public health practice around the world, and organizations such as the American Dental Association (ADA) stand firmly in support of water fluoridation. Many studies support the notion that water fluoridation prevents cavities in children.

"Fluoride was found to significantly reduce tooth decay," Neil Maniar, a professor of public health practice at Northeastern University, told Live Science in an email. "Putting [it] in the water supply is a form of passive prevention that can improve oral health."

Although fluoridated toothpaste has many of the same tooth-protecting properties of fluoridated water, experts say the latter comes with certain public health benefits that toothpaste lacks. That's because ingesting fluoride, rather than brushing with it, leads to more constant levels of fluoride in the mouth throughout the day, which is especially beneficial for children with developing teeth. Fluoridated water also provides a baseline level of protection for lower-income people who may not have consistent access to fluoridated toothpaste or to other forms of dental care.

"It is a way for everyone in a community to benefit from fluoride in a cost-effective manner," Maniar said. "While we often take access to a dentist and even something as simple as being able to brush teeth twice a day for granted, this is a challenge in many communities."

That was true in decades past — but some recent research is raising the question of how helpful fluoridated water is for cavity prevention.

A review of over 150 studies showed that, in recent years, water fluoridation may not be as effective at preventing cavities as it was in the 1970s, after fluoridated toothpaste became more widespread. This change may be because fluoridated toothpaste is providing enough benefit that fluoridated water no longer makes as dramatic of a difference.

However, it's important to note that the review did not include any studies from low-income countries, where fluoridated toothpaste may be less readily available. The review also notes that challenges in measuring the effects of fluoridation programs make their potential benefits difficult to quantify over time.

Is fluoridated water safe?

Both the CDC and the ADA maintain that at the levels found in the public water supply — about 0.7 mg per liter — fluoride is beneficial to public dental health and carries few documented risks.

Still, fluoride has been the focus of much safety research, and the topic continues to be a matter of public interest and controversy.

It's well known that excessive fluoride consumption can lead to fluorosis, the condition behind the "Colorado brown stain" observed by McKay in Colorado Springs. Dental fluorosis causes mottled white, yellow or brown spots and stains to appear on the teeth. But it does not compromise oral health.

Consuming even higher levels of fluoride over a long period of time can also lead to a condition called skeletal fluorosis, which compromises the integrity of the bones. This is because excessive deposits of fluoride in the skeleton causes the bones to become hard and brittle, making them more susceptible to fractures.

Both dental fluorosis and skeletal fluorosis generally occur in regions with abnormally high levels of natural fluoride deposits that leach into the water supply. Because skeletal fluorosis requires extremely high levels of fluoride exposure, it's mostly observed in regions with fluoride-contaminated groundwater, but dental fluorosis can occur due to low-level fluoride exposure through artificially fluoridated water.

Initial concerns about fluoridated water focused on whether it could cause cancer. This belief stemmed from the theory that fluoride build-up in the growth plate of the bones could lead to osteosarcoma, a type of bone cancer. While this connection is difficult to evaluate in humans, most studies have not found any strong evidence for such a link.

Does fluoride affect IQ?

More recently, concerns have been raised about the potential neurotoxic effects of fluoride.

A contentious 2024 monograph from the U.S. National Toxicology Program (NTP) looked back at dozens of studies and reported that high levels of fluoride exposure were associated with lower IQ in children. Between kids with high and low exposure levels, the average IQ difference amounted to about one or two points.

However, the levels of fluoride exposure associated with IQ changes were roughly double the levels of fluoride found in water supplies of countries like the U.S. or the U.K. — about 1.5 mg per liter. The authors also noted that, while high fluoride levels are correlated with cognitive differences in children, their results do not show that fluoride is a cause of cognitive changes.

Recently, further doubt has been cast on the studies that find a link between fluoride and decreased IQ. Reviewers at the National Academies of Science, Engineering, and Medicine pointed out major methodological and statistical problems with the NTP's monograph twice before the NTP self-published the report.

A new article that repeated the results of the NTP monograph was later published in January 2025, and researchers then pointed out that about 70% of the studies included in the meta-analysis were at high risk of bias. The association the NTP found between high levels of fluoride and IQ may not be reliable, these scientists concluded, adding that the report provided "no evidence of an adverse effect at the lower water fluoride levels" used by fluoridation programs.

Still, some researchers are continuing to investigate the minimum amount of fluoride that could potentially cause neurological effects. So far, the results are mixed — a few dozen studies have reported a relationship between aspects of cognition, such as executive function or IQ, and the levels of fluoride exposure found in artificially fluoridated water supplies. But many others have failed to replicate this link.

Many studies that tie fluoride to negative effects have been poor quality, meaning they may suffer from issues such as small sample sizes or using inconsistent or inaccurate methods. High-quality studies have been less likely to show a link between fluoride exposure and negative cognitive outcomes.

Making a determination about the safety of fluoride is challenging because when individual studies use varied methods, focus on different populations, or examine separate outcomes, it becomes difficult to compare across those studies. And because different studies find conflicting results, it's not possible to point to a single study that can prove or disprove the safety of fluoride. As a result, many experts say more high-quality research is still needed to draw a conclusion on the safety of fluoride.

"It's a very nuanced issue," Deborah Dewey, a professor of pediatrics and community health sciences at the University of Calgary and the author of a study investigating fluoride exposure and executive function in preschoolers, told Live Science. "I don't think there's a right or wrong answer right now."

Fluoride and oral health equity

Ultimately, Maniar said the conversation about fluoride really needs to be a discussion about improving oral health equity.

"Rather than focusing on fluoridation, we should be talking about the disparities that exist in oral health care, the cost burden of routine oral health care, and the significant gaps that exist related to education on oral health," Maniar said.

"The linkage between oral health and a range of serious health issues is becoming more clear every day," he said, referring to research that connects poor oral health and conditions including heart disease and pneumonia. "It's critical that we deploy all available tools to address oral health in the same manner that we would address physical and mental health."

Editor's note: This story was updated on Jan. 7, 2025 to note the publication of the NTP's meta-analysis and the resulting critiques of the research. The story was first published Dec. 28, 2024.

This article is for informational purposes only and is not meant to offer medical advice.

The idea that comets delivered water to early Earth has fallen out of favor in the past decade, but a new look at data from the European Space Agency's (ESA) Rosetta mission to an iconic “rubber ducky” comet has reopened that possibility.

Water has a pretty simple chemical makeup: just three atoms (two hydrogen and one oxygen) in each molecule. It's also one of Earth's most abundant molecules, with our planet's oceans brimming with about a million trillion tons of the liquid.

How all of this water ended up on Earth, though, has remained a mystery. Some scientists think that although Earth's geological processes may have generated a tiny fraction of it, most water was likely deposited by comets or asteroids via repeated, cataclysmic collisions.

Figuring out which of these two groups was responsible involves a special chemical signature that arises because the hydrogen in water occurs in two distinct isotopes, or forms. Whereas most hydrogen atoms contain just one proton in their nucleus, a tiny fraction harbors an additional neutron. The chemical signature involves measuring the amount of this heavier hydrogen isotope, called deuterium, relative to its lighter, regular form — a quantity called the deuterium-to-hydrogen ratio, or D/H.

"The D/H in water tells us at what temperature the ice formed, and from that how far a comet formed from the Sun," Kathleen Mandt, a planetary scientist at NASA and corresponding author of a new study describing the reanalysis, told Live Science in an email. The lower the D/H value is, the farther from the sun the asteroid or comet was born.

Related: 'Crumb trails' of meteoroids could reveal potential 'planet-killer' comets years before they reach Earth

Research over the past few decades has shown that Earth's D/H ratio is similar to those of many asteroids and a handful of Jupiter-family comets — a group of comets that swing past the sun roughly every 20 years and whose paths are tweaked by Jupiter's gravity.

But the D/H value of the "rubber ducky" comet 67P/Churyumov-Gerasimenko, determined in a 2015 study, essentially ended the case for comets. Averaged over 150 measurements collected by ESA's Rosetta mission during the spacecraft's 2014 rendezvous with Comet 67P, the D/H value was roughly three times Earth's. The researchers interpreted this as evidence that comets were very unlikely to have delivered water to Earth.

The results were perplexing, Mandt said, because the D/H value was way higher than those of other Jupiter-family comets. Plus, "the comet should have a lot more CO [carbon monoxide] and N2 [nitrogen] than Rosetta measured because these ices also form at really cold temperatures," she added.

To understand Comet 67P's apparently high D/H ratio, Mandt and other astronomers from research institutes in the U.S., France and Switzerland decided to comb through the entire Rosetta dataset. Using an innovative statistical technique developed by Jacob Lustig-Yaeger from the Johns Hopkins Applied Physics Laboratory, the team identified signals coming only from deuterium-containing water molecules, allowing them to collate about 4,000 D/H measurements.

The researchers found that the D/H values varied wildly along the comet's long axis, with the highest being near the "nucleus" — the rocky part that resembles a rubber ducky — and decreasing along the tail.

Such variation likely occurs because of processes occurring within the comet, the researchers wrote in their study, published Nov. 13 in the journal Science Advances. As the comet approaches the sun, the comet's surface warms up, which releases gas along with ice-coated dust particles into the coma (the halo that develops around the nucleus). Previous, unrelated lab studies had shown that deuterium-containing ice tends to stick to dust grains more than to normal ice. The scientists realized that such dust grains, upon entering the coma, could account for the high D/H values recorded there.

However, the researchers noted that dust particles about 75 miles (120 kilometers) from the nucleus are essentially dried out, meaning they lack any deuterium-enriched ice that could generate spuriously high D/H values. Using only the data collected at this distance, the authors calculated that Comet 67P's actual D/H value was only 1.5 times that of Earth.

The revised D/H value means that "all Jupiter Family Comets that we have been able to measure have a D/H closer to the Earth's water D/H," Mandt said. This implies that comets played a major, rather than minor, role in irrigating Earth. Plus, she added, a lower D/H value suggests Comet 67P was born closer to the sun than scientists previously thought.

Earth's total fresh water has plummeted to an alarming new low, and it could be a sign that climate change is pushing the world into a dangerous phase of global drying, according to a new study.

Since 2015, our planet's lakes, rivers and aquifers have lost 290 cubic miles (1,200 cubic km) of fresh water, the equivalent of emptying Lake Erie two and a half times.

This drop coincided with a 2014 to 2016 period of El Niño warming. Scientists typically expect freshwater levels to rebound after the climate oscillation ends, but satellite measurements, made up to 2023, reveal that the freshwater levels have yet to recover — and may never come back.

"We don't think this is a coincidence, and it could be a harbinger of what's to come," study lead author Matthew Rodell, a hydrologist at NASA's Goddard Space Flight Center, said in a statement.

The researchers published their findings Nov. 4 in the journal Surveys in Geophysics.

Related: Will the US run out of water?

As climate change causes temperatures to rise around the globe, water evaporates more readily from its surfaces, and the atmosphere gains an ever increasing capacity to absorb it. This means that when downpours do occur, they are more torrential — dumping more rain in faster and more powerful storms that are more likely to run off than to seep into drier and more compact surfaces.

This issue, alongside destructive land use and the mismanagement of water resources, means that nearly 3 billion people and over half of global food production are facing "unprecedented stress" on their water systems, according to one recent study.

To investigate the extent of our planet's drying, the researchers behind the new study turned to two pairs of satellites that orbit above the North Pole. The satellites measured water levels by detecting the minute fluctuations that water's mass produces to Earth's gravitational field.

By precisely measuring the changes to the tugs of Earth's gravity from 2015 to 2023, the scientists found that the 290 cubic miles of water that was lost from the world's surface during the last El Niño never returned, and that 13 of the world's 30 most intense droughts seen by the satellites took place since January 2015.

The result is an ominous one. The satellites used in the study are set to produce six more years of readings before they are retired. Whether fresh water will rebound to pre-2015 levels during that period, stay at the same value or continue to decline remains unclear. But the researchers are far from hopeful.

"There is much debate and little consensus about how patterns of wetting and drying will manifest in a warming world," they wrote in the study. "Hence, it is difficult to evaluate whether the observed patterns are consistent with predictions and likely to persist."

For the first time, researchers have captured nanoscale video footage of hydrogen and oxygen atoms combining into water out of "thin air" — thanks to a rare metal catalyst. The super-efficient reaction, which could one day help astronauts make water in space, also produced the smallest bubble of water ever seen, researchers say.

The video was part of a new study, published Sept. 27 in the journal PNAS, in which researchers tested how palladium catalyzes a reaction between hydrogen and oxygen gases to create water in standard lab conditions. The team studied this reaction with a new type of monitoring apparatus that captured the process in extraordinary detail.

"We think it might be the smallest bubble ever formed that has been viewed directly," study lead author Yukun Liu, a materials scientist at Northwestern University in Illinois, said in a statement. "Luckily, we were recording it, so we could prove to other people that we weren't crazy."

The team induced the reaction using a special ultra-thin glassy membrane that holds gas molecules within honeycomb-shaped "nanoreactor" chambers. This means the tests can be viewed in real time using electron microscopes, enabling the researchers to learn more about how the reaction works.

Researchers from the Northwestern University Atomic and Nanoscale Characterization Experimental Center (NUANCE) pioneered this novel technique in a study published in January.

Related: New reactor could more than triple the yield of one of the world's most valuable chemicals

Researchers have known since the 1900s that palladium, a silver-white rare metal similar in appearance to platinum, can catalyze a dry reaction between hydrogen and oxygen, researchers wrote. However, until now, it was unclear exactly how the reaction worked.

The new study revealed that the gaseous atoms first squeeze between the palladium atoms, which are arranged in a square lattice. This expands the lattice and enables water droplets to form on the catalyst's surface. The team also found that the process can be sped up by adding hydrogen atoms to the palladium first, because they are smaller than oxygen atoms. This enables the palladium lattice to expand before the oxygen is added, creating bigger gaps for the larger atoms to fit more readily inside.

The team believes that a scaled-up version of the reaction could be used to create water for astronauts in space or in colonies on other planets. The researchers compared it to a scene from the sci-fi film "The Martian" starring Matt Damon, in which a stranded astronaut makes water on Mars by burning rocket fuel and combining it with oxygen from his suit.

"Our process is analogous, except we bypass the need for fire and other extreme conditions," study co-author Vinayak Dravid, director of the NUANCE Center, said in the statement. "We simply mixed palladium and gases together."

Palladium is an expensive and rare material, costing upwards of $1,000 per ounce. This is largely because it can catalyze many other chemical reactions and is used in a wide range of technologies. As a result, creating a water-generating device for astronauts could be extremely costly.

However, the researchers argued that it would be worth the expense in the long run.

"Palladium might seem expensive, but it's recyclable," Liu said. "Our process doesn't consume it. The only thing consumed is gas, and hydrogen is the most abundant gas in the universe."

Imagine you're exercising outside on a hot day. You're drenched in sweat, and the feeling of thirst begins to overwhelm you. You take out your water bottle and swallow your first big gulp — and your body immediately fills with relief and elation.

"There's a hedonic reaction to it," Patricia Di Lorenzo, a professor emeritus of psychology at Binghamton University in New York, told Live Science. "When you're really thirsty and you drink water, it just tastes so good."

But why does drinking water feel so pleasurable when you're thirsty?

We get thirsty when we exercise heavily, because as we sweat, our blood volume decreases. Most areas of the brain are separated by the blood-brain barrier, a layer of cells that prevents harmful toxins and pathogens from infecting the brain. But certain parts of the brain fall outside this barrier, allowing for rapid detection of changes in our blood. When we lose blood volume from exercising or eating salty foods, neurons in these parts of the brain send a signal to trigger the feeling of thirst.

"This rapid response is very important for survival," Yuki Oka, a biology professor at Caltech, told Live Science. "If it takes so long, then you might get dehydrated."

Related: How much water do you really need to drink?

Three parts of the brain process thirst: the subfornical organ (SFO), the organum vasculosum lamina terminalis (OVLT) and the median preoptic nucleus (MnPO). Both the SFO and OVLT are located outside the blood-brain barrier. In a 2018 study in mice, Oka uncovered that while all three areas have neurons that drive drinking when those nerve cells are excited, the MnPO is in the middle of this process. It transmits thirst signals from the SFO and OVLT to other parts of the brain to prompt drinking.

It takes about 30 minutes after you swallow water for it to be absorbed and circulate in your body, Oka said. But your body begins to send signals to your brain that you are receiving water well before you are fully rehydrated. With just the initial sip, your brain releases a rush of the neurotransmitter dopamine. Most scientists agree that dopamine is involved in reward-seeking, movement and motivation. Critically, dopamine prompts animals to exert energy on acts that give us a reward or help keep us alive, including eating and drinking.

If dopamine is released when they do a specific behavior, "animals tend to repeat that behavior," Oka said. "That's a positive signal."

Exactly how drinking water triggers the release of dopamine is still unknown. But in a 2019 study published in the journal Neuron, Oka and his colleagues discovered that thirsty mice that drank water released dopamine, whereas thirsty mice that received water directly to their gut did not. This suggests the act of drinking — and not thirst satiation — releases the neurotransmitter. Oka said this explains why dehydrated patients who are administered IV fluids don't experience the same reward they do from drinking a cold glass of water.

In a separate process, the act of gulping also sends a message to neurons in the MnPO that the body is receiving water, per the study. The MnPO then deactivates thirst neurons in the SFO, giving a feeling of satiation.

Yet gulping isn't the only mechanism that helps to halt thirstiness. After water travels down to the gut, the body detects a drop in the blood's salt-to-water ratio. This leads to a rise in the levels of a hormone called vasoactive intestinal peptide (VIP). This hormone, rather than the water itself, helps to activate neurons that signal to the brain that the body is satisfied. Much about how this process works is a mystery; researchers still don't know where VIP comes from or how its release is triggered.

"We don't even know how osmolality [concentration of dissolved particles in the blood] is detected by these intestinal cells," Oka said. "We're working on that."

The processes that quickly relieve thirst help prevent overhydration, Oka noted. But he also wonders whether they evolved to aid the survival of not just each individual but also the survival of a group. When critical resources such as water are limited, a quick stop to thirst may help keep a species alive. The hypothesis has yet to be tested, but Oka is intrigued by the idea.

"That's a very interesting experiment in how to share," he said. "If that's really true, the neurocircuit has evolved to thinking about … others, not just the self."

2023 was the hottest summer in the past 2,000 years, and summer 2024 is looking to be just as intense. As summer peaks, freshwater lakes and pools all over the United States will likely be filled with people trying to cool off. But as the temperatures of these freshwater environments rise, the organisms that live in them can shift, posing harmful, or even lethal, threats to swimmers. 

Naegleria fowleri is one such threat that seems primed to start infecting more people — but surprisingly, it hasn't done so yet. 

N. fowleri is a single-celled organism that loves warm temperatures, lives in soil and fresh water, and preys on bacteria, much like many others of its kind. The amoeba can lurk in lakes, rivers, hot springs, well water, tap water and poorly maintained swimming pools, among other water sources. 

What's harrowing about this tiny organism is that it can enter the brain via nerves in the nose and then decimate brain cells. This rare infection can lead to a fatal condition called primary amoebic meningoencephalitis (PAM), which is why N. fowleri is commonly known as a "brain eating amoeba."

Related: Rare 'brain-eating' amoeba infection behind death of 2-year-old in Nevada 

N. fowleri infections that lead to PAM are relatively rare in the U.S., averaging about zero to eight laboratory-confirmed cases per year. Although all incidents of PAM are caused by an N. fowleri infection, this fatal disorder can sometimes be misdiagnosed as other, more-common infections of the nervous system, such as bacterial meningitis and viral encephalitis. Such misdiagnoses may mean that some cases of PAM are missed.

Symptoms of PAM typically start one to 12 days after a person is exposed to the amoeba, and patients die within one to 18 days of symptoms starting. Testing for an N. fowleri infection is also a slow process, further complicating diagnosis, and there are no specific drugs to kill the amoeba. 

Historically, diagnosed N. fowleri infections have been concentrated in warmer, Southern states. In recent years, however, the amoeba has been detected — and even caused infections — farther north, including in Iowa, Nebraska and Minnesota. The reason behind this is climate change. 

The infections seen in northern latitudes have researchers worried that warming temperatures could make N. fowleri infections more common.

Leigha Stahl, a faculty member at the University of Alabama, recently published work on determining how changes in the environment affect the growth of N. fowleri populations. Stahl found that N. fowleri can withstand high temperature changes that other waterborne microorganisms cannot. This resilience means the amoeba can outlive its competition and thus increase its access to resources. 

According to Stahl, the amoeba can survive at a range of temperatures and acidity levels. It can grow in temperatures up to 115 degrees Fahrenheit (46 degrees Celsius) but has also been known to proliferate in temperatures as low as 80 F (26 C). 

"It can definitely thrive in a variety of different environments," Stahl told Live Science. As the temperatures in U.S. lakes and rivers increase — either from the overall warming of the planet or thermal pollution from manufacturers that use the water as a coolant — this fosters a more suitable environment for N. fowleri to flourish, she said.

Warming temperatures are not the only thing that could spur the spread of N. fowleri, however. Stronger and more frequent storms due to climate change can cause local changes in water levels and increase the amount of organic matter that ends up in the water from runoff. This runoff can provide nutrients to organisms in the water, including brain eaters. Storms could not only spread more N. fowleri from land to water but also change the levels of other aquatic microorganisms. 

Related: Fatal 'brain-eating' amoeba successfully treated with repurposed UTI drug 

"What you might see is spikes in these organisms after an extreme weather event," said Charles Gerba, a professor of microbiology and public health at the University of Arizona. "So the more nutrients in the water, the more bacteria you'll get," Gerba told Live Science.

"You could have less dissolved oxygen … more blooms of different things … maybe a greater proliferation of bacteria," Stahl added. "And if there's a greater amount of prey sources in the water, maybe that would allow the N. fowleri to eat more or be happier." 

Already, massive changes in our freshwater sources have coincided with increases in the detection of N. fowleri in both Southern and Northern latitudes. And yet, paradoxically, there has yet to be a significant uptick in confirmed brain-eating amoeba infections. We're still seeing about one to two a year — but why? 

The previously mentioned difficulties in diagnosing N. fowleri infection could be a factor, meaning cases might just be going unreported. Plus, Gerba said he believes it goes underdiagnosed for other reasons, particularly in northern areas. 

"We're seeing it creeping up to states further and further north all the time," Gerba said. "Somebody in Minnesota or Michigan doesn't even consider that as a potential case of infection when they see it, so that's probably how they're being missed." 

Evidence backs the idea that PAM cases can go underreported due to a lack of expertise among medical staff about the very rare condition, as well as the fact that autopsies are not always carried out on deceased patients.

In addition to getting more cases up north, as summertime temperatures stick around for longer, "the time period when you'll find N. fowleri will increase," Gerba said. With cases of N. fowleri infections on the rise in other countries, experts are urging U.S. clinicians to become more aware of the signs and inform more of the public about these brain-eating amoebas. 

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