High up in the icy mountains of Norway, archaeologists have discovered a unique 1,500-year-old reindeer trap, alongside several mysterious wooden objects, including a decorated boat oar that seems out of place 4,600 feet (1,400 meters) above sea level.

"These are items we would never find in ordinary excavations, including a pine oar and a clothing pin made of antler," Leif Inge Åstveit, an archaeologist at the University Museum of Bergen, said in a statement from the Vestland County Municipality. "The pin is shaped like a miniature axe — truly exceptional finds."

Archaeologists have been excavating in the mountainous Aurlandsfjellet area of western Norway since August. They discovered hundreds of tree branches piled into two wooden barriers that likely functioned as a kind of hunting blind or trap.

"A 1,500-year-old mass trapping facility composed of wooden branches that is literally melting out of the ice in front of our eyes is probably unique in both Norwegian and European contexts," Åstveit said.

The team also found a significant number of reindeer antlers near the trapping facility. All had cut marks, suggesting that the animals were trapped, killed and potentially processed on-site.

In addition to the trap, the archaeologists recovered numerous artifacts assumed to be directly linked to the hunt, including iron spears, wooden arrows and three bows. The finds also included a delicate brooch made from antler and shaped like a miniature ax, which was perhaps accidentally dropped by a hunter during the kill, according to the statement.

But the archaeologists are stumped by the intricately carved wooden oar they found. Further study in the coming years may help to clarify why the oar was carried up the mountains.

Experts think the reindeer trapping site was preserved thanks to the onset of a cooling period in the mid-sixth century. Cold temperatures may have led to an increase in snowfall and ice, causing the hunters to abandon the site. The exceptional preservation of the antlers suggests the hunting facility was buried by snow and ice shortly after it was abandoned, according to the statement.

"This discovery opens up entirely new interpretations and understandings of how these facilities functioned," Åstveit said. "The exceptionally well-preserved antler and wood materials will contribute significantly to research in the coming years."

Global warming is contributing to the reemergence of ice-covered sites like this one, according to the statement. A similar site with reindeer-hunting weapons and blinds was discovered in Norway's mountains in 2022. Nordic archaeologists also recently recovered 1,300-year-old wooden skis, a Viking horse bridle and a 1,700-year-old leather sandal melting out of glaciers.

The mountain glaciers of Yosemite National Park are projected to melt away in 75 years or less. Now, new research finds that their loss will be the first time humans have ever seen the Sierra Nevada mountains without ice.

According to a new study, published Wednesday (Oct. 1) in the journal Science Advances, the Sierra Nevada's glaciers have not disappeared since the last ice age. Because they reached their maximum extent during the ice age about 30,000 years ago, and because humans aren't thought to have arrived in North America until after 30,000 years ago, that means people have never witnessed an ice-free Sierra Nevada, according to the study.

"Anthropogenic climate change is therefore likely creating a no-analog scenario in the western United States within the current interglacial," the researchers wrote in the new paper.

Geoscientists have long known that the extent of the mountain glaciers in what is now the western U.S. shrank and grew over the last 11,700 years, a timeframe known as the Holocene. In the warm early Holocene, the Sierra glaciers got smaller before expanding again in the mid-to-late Holocene. They've since shrunk in the last century, contracting from formidable ice walls hanging above steep slopes into small snowfields barely clinging to existence.

What was unclear was whether these glaciers ever fully disappeared. Some studies of glacial sediments in lakes below the ice suggest they may have vanished in the early Holocene, only to reform 3,000 years ago.

To get a clearer picture, the researchers tested samples of boulders and recently-exposed bedrock from near four retreating glaciers in and near Yosemite National Park: Conness, Maclure, Lyell and Palisade. They were looking for particular variations of carbon and the element beryllium that are formed only when cosmic rays from the sun hit the rock.

Since these variations don't form when the rocks are buried and sheltered from the sun, their presence can reveal when the rock was exposed. And because the variations decay away at known rates, they also provide a "clock" that gives a date for that exposure.

The results suggest that the rocks beneath these long-lasting glaciers have been exposed for between less than 100 to several thousand years, and that none of the glaciers have ever fully disappeared — though the eastern section of the Lyell glacier may have been even smaller than it was today during the early Holocene. This tracks with the current warming trends, the study authors wrote: California's recent summer warming of 3.6 degrees Fahrenheit (2 degrees Celsius) over pre-industrial temperatures is comparable to or larger than the climate 11,000 years ago.

Prior to the Holocene, during the ice age — scientifically known as the Last Glacial Period — the Sierra Nevada glaciers would have been beefier, peaking around 30,000 years ago. Humans are confirmed to have been living in North America as early as 23,000 years ago. Some controversial archaeological evidence puts people in northwestern New Mexico around 30,000 years ago. Either way, it's unlikely that humans ever set eyes on an ice-free Sierra Nevada.

"[Our] reconstructed glacial history indicates that a future glacier-free Sierra Nevada is unprecedented in human history," the authors wrote.

Glaciers in Washington, Montana, British Columbia, Alberta and the Swiss Alps lost an unprecedented amount of ice between 2021 and 2024, a new study reveals.

The cumulative loss in these four years was double that recorded between 2010 and 2020, shrinking glaciers by up to 13%, researchers found. Glaciers in the U.S. and Canada lost 24.5 billion tons (22.2 billion metric tons) of ice per year on average, while glaciers in the Swiss Alps lost 1.7 billion tons (1.5 billion metric tons) of ice per year.

"Previous records were shattered," study co-author Matthias Huss, a lecturer in the Department of Civil, Environmental and Geomatic Engineering at ETH Zurich in Switzerland, told Live Science in an email. "We knew that these extreme glacier melt rates would come up. Nevertheless, the day you go out and witness these results based on the measurements, it is still surprising and difficult to accept."

The studied glaciers are located in regions where there is "very good, almost real-time, observational coverage," Huss said. The yearly losses of ice from these glaciers between 2021 and 2024, as well as the total loss of ice measured during this period, are record-breaking.

"Meteorological conditions that favored high rates of mass loss included low winter snow accumulation, early-season heat waves, and prolonged warm, dry conditions," the researchers wrote in the new study, published June 25 in the journal Geophysical Research Letters.

Between 2000 and 2023, glaciers around the world collectively lost 301 billion tons (273 billion metric tons) of ice per year, contributing to around one-fifth of observed sea-level rise, according to the study. The aim of the new research was to determine whether the past four years of glacier melt stood out from previous years.

Related: World's glaciers are losing enough ice to fill 3 Olympic pools every second, terrifying new study finds

The researchers found that 2021 to 2024 was the worst period for ice loss since glacier monitoring began in the 1960s. Glacier ice loss was extreme over the four-year period, with one-tenth of all glacier ice in Switzerland melting away in just two years between 2022 and 2023, Huss said.

"It is interesting but also alerting to see that these extremes are widespread and do not occur only in a single region but globally, even though the exact timing of the most important melt years is often not the same," he said.

Glacier ice loss not only exacerbates sea level rise but also threatens freshwater availability, elevates the risk of geohazards and drastically alters mountain landscapes, according to the study.

Heat waves and wildfires

To examine glacier melt, the team used data from the World Glacier Monitoring Service and airborne surveys, as well as climate records and satellite observations. They fed this information into a computer model to evaluate mass changes for two U.S. glaciers, three Canadian glaciers and five Swiss glaciers. The two U.S. glaciers were the South Cascade Glacier in Washington state and the Sperry Glacier in Montana. The three Canadian glaciers were the Place, Peyto and Helm glaciers.

Both in North America and Switzerland, one of the biggest factors driving glacier melt was extremely high summer temperatures. A heat wave in June 2021 in the U.S. and western Canada resulted in huge snowpack losses, and another heat wave in 2023 caused an early start to the wildfire season, which indirectly affected glaciers through soot particles that darkened the ice.

Darker surfaces from soot and other impurities absorb more radiation from the sun than light surfaces do, leading to more melt. More melt exposes vegetation, which is even darker than darkened ice and, therefore, leads to more heat absorption. This additional heat absorption on Earth's surface gradually contributes to global warming, as the heat is no longer reflected back out to space, which, in turn, leads to more wildfires and more soot deposition.

Another important factor driving glacier melt was the loss of firn zones, which are areas where snow has not yet been compressed into ice. The snow in these zones has a granular texture that helps to retain meltwater and prevent runoff, and it also reflects more sunlight back out to space than ice does, according to the study.

Computer models of glaciers do not currently account for firn zones and the influence of soot and other impurities. The effects of extreme weather events, such as wildfires and heat waves, should also be considered, the study authors argued.

Peak glacier ice loss

The study also found that ice loss from glaciers may have peaked between 2021 and 2024, raising serious concerns about water management in some regions, Huss said.

"It is not that melting will decline in the future with additional warming but the huge losses have resulted in rapidly shrinking ice cover and in some regions even a complete disappearance of small glaciers," he said.

This means that glaciers may now release less water into rivers and streams than they did up until 2024, even if global temperatures keep increasing. Communities, agriculture and industries that rely on glacier meltwater may therefore see their supply dwindle in the coming years.

The results are alarming and "clearly fit the global trend," Huss said. However, it's important to note that "we are highlighting two regions [western U.S.-Canada and the Swiss Alps] with absolutely exceptional changes in single years that will not immediately be reflected in all regions," he said.

Scientists have discovered that a glacier in the Russian Arctic is retreating extremely quickly — and its rapid retreat has exposed a graveyard of ancient whale bones.

The research expedition landed on Wilczek Island, in the far north of Russia, earlier this year to study permafrost, according to a statement from the Arctic and Antarctic Research Institute (AARI) in Russia.

Using satellite imagery, the team compared current and past positions of the glacier, Nikita Demidov, an AARI geologist, said in the statement. The scientists found that the ice cap on the island had split into two parts over a period of less than 20 years.

This glacier's decline is part of a wider shift — a study from February found that, since 2000, glaciers have lost about 5% of their ice globally.

Related: Dramatic transformation of the Arctic landscape may be permanent

The schism in the ice revealed several square miles of the island's surface, which held a large number of whale bones. Some of the skeletons are well preserved. Demidov noted that the bones are worst preserved near the seashore, where they have had longer to thaw, and are best preserved closest to the glacier.

"The paleontological find indicates an episode of extremely rapid sea level change in the area of the northernmost archipelago of Eurasia, which occurred in the last few thousand years," he said.

The expedition is being conducted from an Russian ice-strengthened vessel called Professor Molchanov and will continue through August, according to Russian state news agency TASS.

This intriguing astronaut photo shows a trio of "anomalous" ice masses merging in the heart of central Asia. The stripy glaciers are bucking a global trend by gaining volume, despite the effects of human-caused climate change.

The aerial image shows the Lolofond glacier (top) and Teram Shehr glacier (bottom) merging with the Siachen glacier (center), along with a smaller unnamed tributary glacier. The ice masses are located in the Karakoram mountain range, a largely uninhabited area situated alongside the Himalayas in the Kashmir region, where the borders of India, Pakistan, China, Afghanistan and Tajikistan meet.

Siachen is Earth's second-longest glacier outside of Greenland and Antarctica, and is around 47 miles (76 kilometers) long and 2.2 miles (3.5 km) across at its widest point, according to NASA's Earth Observatory. The glacier starts around 19,000 feet (5,800 meters) above sea level, while its end, or terminus, sits at an altitude of around 11,800 feet (3,600 m).

Each of the glaciers in the photo is made up of parallel striations, or lines, known as moraines, which are folds of ice rich in dust and rock that get trapped in between merging glaciers, according to the National Park Service. There is a particularly thick and dark moraine where Teram Shehr and the smaller unnamed glacier merge with Siachen.

Eagle-eyed readers may be able to spot some other unusual features in the image, including a green-hued lake and two large chunks of white ice trapped in a moraine within Siachen (both located near the far left of the photo).

Related: See all the best images of Earth from space

Unlike most of Earth's glaciers, which are rapidly losing their ice as a result of climate change, the Karakoram glaciers have expanded slightly in volume over recent decades. "These gains — known as the 'Karakoram anomaly' — are yet to be fully explained, and scientists question how long they will persist," Earth Observatory representatives wrote.

Some researchers believe that the anomaly can be explained by local weather patterns, while others argue that the dust and dirt in the glaciers' moraines help to insulate the ice from warming temperatures, according to the National Snow and Ice Data Center. Neither explanation is fully accepted by the scientific community.

Siachen is disputed territory, claimed by both India and Pakistan. Both countries have had a military presence near the glacier's summit since 1984 and have clashed on multiple occasions. As a result, the Siachen glacier holds the title of Earth's highest battleground, according to Guinness World Records (GWR).

Around 2,000 soldiers have died during the conflict, but almost all of them were killed by "extreme weather conditions," according to GWR.

Dramatic ice melt due to climate change may move the locations of Earth's geographic poles in the coming years, a new study finds.

As ice sheets melt and ocean mass gets redistributed around the planet, Earth's geographic North and South poles could shift up to 89 feet (27 meters) by 2100 as the planet's axis of rotation changes, according to the study, published March 5 in the journal Geophysical Research Letters. The shift could affect satellite and spacecraft navigation, the researchers said.

As Earth spins, changes in the distribution of the planet's mass cause it to wobble on its axis like a top. Many of these wobbles are regular and predictable — some are due to regular changes in atmospheric pressure and ocean currents, while others result from interactions between the core and the mantle.

Recent studies have suggested that melting ice sheets and glaciers could also affect this mass distribution and shift Earth's poles. In the new study, researchers at ETH Zurich used both the movement of the poles from 1900 to 2018 and projections of ice sheet melt to predict how far the poles might move under different human-caused climate change scenarios.

The North Pole could shift westward by more than 89 feet by 2100 under the worst-case greenhouse gas emissions scenario, the team found. Under a more optimistic emissions scenario, the pole could still shift as much as 39 feet (12 m) relative to its location in 1900. Meltwater from the Greenland and Antarctic ice sheets played the largest role in the simulations, followed by glacier melt.

"This effect is somewhat surpassing the effect of glacial isostatic adjustment, which is the effect of solid Earth rebound after the termination of the last ice age," study co-author Mostafa Kiani Shahvandi, an Earth scientist now at the University of Vienna, told Live Science.

In other words, land at the surface of the crust sunk under the weight of ice age glaciers and rose when they melted, changing the weight distribution in Earth's crust and shifting the poles. "This means that what humans have done has somewhat shifted the pole more than the effect of ice ages," Kiani Shahvandi said.

Causing confusion for sat-nav

A shift in Earth's rotational axis could disrupt satellite and spacecraft navigation, Kiandi Shahvandi said. Scientists map a spacecraft's location in part using Earth's rotation axis as a reference. If that axis shifts over time, it could become harder to pinpoint the spacecraft's exact location.

Future work could involve examining paleoclimate data to determine how much the poles have shifted over millions of years during past episodes of natural climate change. According to Kiandi Shahvandi, this would help reveal the true scale of human impact on the poles' movement.

This story was originally published on April 8.

Earth's glaciers lost 300 billion tons (273 billion metric tons) of ice every year on average between 2000 and 2023, amounting to a 5% decline in volume since the start of the millennium, a groundbreaking new study finds.

The loss equates to roughly three Olympic swimming pools' worth of ice melting or breaking off from glaciers every second, according to the French National Center for Scientific Research (CNRS), which was involved in the study together with dozens of other research institutions.

This startling decline is the result of global warming driven by our ballooning greenhouse gas emissions.

"We expected to find that glaciers are melting, but the amount of ice lost in the past few years is shocking even for us scientists," said lead author Michael Zemp, a professor at the University of Zurich and director of the World Glacier Monitoring Service.

The results revealed extreme losses in glaciers in Europe's Alps and Pyrenees mountains, with both regions showing a 40% decline in glacier volume over the study period. "In the European Alps, glaciers lost 10% of their ice in just two single years," Zemp told Live Science in an email.

Related: Alaska's ice is melting in front of our eyes, staggering satellite shots show

For the study, researchers compiled satellite data and direct measurements of every glacier region in the world except the Greenland and Antarctic ice sheets, which are both so big they have a delayed response to warming, Zemp said.

Scientists gathered and converted hundreds of glacier-related datasets into time series that they could then analyze to paint a global picture of how glaciers have changed over time.

"Over the past 20 years we got a wealth of satellite sensors to estimate glacier elevation and mass changes," Zemp said. "While agreeing in general about glacier melt, the exact numbers differed quite a bit from sensor to sensor" — hence the need to convert all the numbers to one format, Zemp said.

The results, published Wednesday (Feb. 19) in the journal Nature, revealed stark regional differences in ice loss during the study period. Glaciers in the Alps and Pyrenees experienced the greatest decline relative to their size, while glaciers on the subantarctic islands only lost about 2% of their ice, according to a statement from the University of Zurich.

Researchers also found a 36% increase in annual ice loss between the first half of the study period, between 2000 and 2011, and the second half, between 2012 and 2023, suggesting that ice loss is accelerating.

Excluding the Greenland and Antarctic ice sheets, glaciers worldwide held about 134,182 billion tons (121,728 billion metric tons) of ice in 2000. By 2023, that figure had dropped to about 126,971 billion tons (115,186 billion metric tons), according to the study.

The volume of ice lost from glaciers during the study period caused global sea levels to rise by 0.7 inches (18 millimeters), the researchers noted, which is 0.1 inches (2.5 mm) more than the Greenland Ice Sheet has contributed to sea level rise since the 1990s.

Sea level rise is not the only risk linked to glaciers melting. "Glaciers are vital freshwater resources, especially for local communities in Central Asia and Central Andes," study co-author Inés Dussaillant Lehmann, a postdoctoral researcher and glaciologist at the University of Zurich, said in the statement. Dwindling freshwater reserves from glaciers could threaten water security in these regions, according to the statement.

Looking ahead

The new research is the first to paint a consistent global picture of glacier ice loss and will provide a foundation for similar studies in the future, said Samuel Cook, a glacier modeling expert and junior research group leader at the University of Erlangen-Nuremberg in Germany who was not involved in the study.

"This is about as robust a piece of global-scale data analysis as it's possible to have," Cook told Live Science in an email. "The thing that stands out to me is the sheer methodical thoroughness of the authors and the scale of the study."

The first quarter of the 21st century saw glaciers worldwide decline by 5% — but this is just a fraction of what could unfold over the next decades.

Previous modeling revealed that at least 25% of the ice that remains in glaciers today will be lost by 2100 even if we slash our greenhouse gas emissions, because glaciers have a delayed response to climate change, Zemp said. Should emissions remain the same or increase, the world could lose 50% of its remaining glacier ice by the end of this century, he said.

Only immediate action can stave off the worst outcomes, Zemp said. "Every tenth of a degree [Celsius] of avoided warming will help to preserve glaciers and will save us from related downstream impacts," he said.

Diamond Beach is a strip of jet-black sand covered in sparkling chunks of ice. The beach is a stone's throw away from Iceland's Jökulsárlón glacier lagoon, a clear lake that ferries giant icebergs to the Atlantic Ocean.

The icebergs originate from the Breiðamerkurjökull glacier, which discharges meltwater and ice into the Jökulsárlón glacier lagoon. The bergs and other glacial debris float lazily around the lagoon and eventually find their way to the ocean via a short waterway that runs perpendicular to the coastline.

Related: Polar bear sleeping on tiny iceberg drifting in Arctic sea captured in heartbreaking photo

But not all the fractured ice makes it out to sea. Blocks of it wash up on Diamond Beach — or "Breiðamerkursandur" in Icelandic — where they glisten like gemstones strewn across the black sand, according to Guide to Iceland. The "diamond" effect grows stronger with time, as the waves and wind polish the stranded ice chunks.

Diamond Beach is one of several black sand beaches in Iceland. The beach owes its striking color to past volcanic activity that painted the landscape with a type of dark, runny lava called basaltic lava. This lava hardened into basalt rocks, and these were then ground into black sand by moving glaciers, according to Guide to Iceland.

Diamond Beach sits downstream from Europe's largest ice cap, Vatnajökull, which is rimmed on all sides by glaciers — including the Breiðamerkurjökull and nearby Fjallsjökull glaciers.

And if the bejeweled appearance of Diamond Beach wasn't mesmerizing enough, the sandy stretch is home to seals and is one of the best spots in Iceland to watch orcas from the shore. It's also an excellent location to see auroras (also called the northern lights) in the winter, according to Guide to Iceland.

As humans alter the planet's climate and ecosystems, scientists are looking to Earth's history to help predict what may unfold from climate change. To this end, massive ice structures like glaciers serve as nature's freezers, archiving detailed records of past climates and ecosystems — including viruses.

We are a team of microbiologists and paleoclimatologists that studies ancient microorganisms, including viruses preserved within glacier ice. Along with our colleagues Lonnie Thompson, Virginia Rich and other researchers at the Ice Core Paleoclimatology group at The Ohio State University, we investigate interactions between viruses and their environment archived in ice cores from the Guliya Glacier on the Tibetan Plateau.

By linking the genomes of ancient viral communities to specific climate conditions preserved in glacier ice, our newly published research offers insights into how these viruses have adapted to Earth's shifting climate over the past 41,000 years.

Reading history in viral genes

We primarily used metagenomes — collections of genomes that capture the total genetic content of all microorganisms present in environmental samples — to reconstruct viral genomes from nine distinct time intervals within the Guliya ice core. These time horizons span three major cold-to-warm cycles, providing a unique opportunity to observe how viral communities have changed in response to different climatic conditions.

Through our analyses, we recovered the genomes of the equivalent of 1,705 virus species, expanding known glacier-preserved ancient viruses more than fiftyfold.

Only about one-fourth of the viral species we found shared species-level similarities with any of the viruses identified in nearly 1,000 metagenomes previously captured in global datasets. Most of these overlapping species were also from the Tibetan Plateau. This suggests that at least some viruses preserved in the Guliya Glacier originated locally in the region, but it also spoke to the relative lack of glacial viruses in available databases.

Using these new reference genomes, we attempted to "read" their stories.

Related: Some viruses have a mysterious 'Z' genome

One key finding was that viral communities varied significantly between cold and warm climatic periods. The most distinct community of viral species on the glacier appeared about 11,500 years ago, coinciding with the major transition from the Last Glacial Stage to the Holocene. This suggests that the unique climate conditions during cold and warm periods profoundly influenced the composition of viral communities. We hypothesize that these influences were likely due to viruses from other places being blown in by changing wind patterns and subject to selection pressures from changing temperatures on the glacier.

Digging deeper, we next determined how viruses interacted with their hosts. To do this, we used computer models to compare viral genomes with the genomes of other microbes also found in this environment. We found that viruses consistently infected Flavobacterium, a lineage of bacteria commonly found in glacier environments.

We also learned that viruses on the Guliya Glacier must "steal" genes from their hosts to manipulate their metabolisms. Encoded within the viral genomes were 50 auxiliary metabolic genes related to metabolism, including the synthesis and breakdown of vitamins, amino acids and carbohydrates. Some of these genes were abundant across all nine time intervals studied, suggesting that they help microbial hosts cope with the harsh conditions on glacier surfaces and thereby improve viral fitness.

Thus, viruses not only infect and kill cells, but they likely also alter the fitness of their hosts during infection, in turn influencing their capacity to survive in the extreme conditions of glacier environments.

Climate change over time

Our findings offer a novel perspective on how life, in the form of viruses, has responded to climatic changes over tens of thousands of years.

Understanding these ancient interactions provides a unique opportunity for future research in both virology and climate science. By studying how ancient viruses responded to past climate changes, researchers can gain valuable insights into how viruses adapt to ongoing global climate change.

We believe that glacier ice, by capturing information on microorganisms and their ecosystems over time in each layer, remains a critical resource for unraveling the history of Earth's climate and the life it has supported — especially as glacier ice reserves rapidly diminish.

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

Antarctica's Thwaites Glacier got its nickname the "Doomsday Glacier" for its potential to flood coastlines around the world if it collapsed. It is already contributing about 4% of annual sea-level rise as it loses ice, and one theory suggests the glacier could soon begin to collapse into the ocean like a row of dominoes.

But is that kind of rapid collapse really as likely as feared? A new study of Thwaites Glacier's susceptibility to what's known as marine ice cliff instability offers some hope. But the findings don't mean Thwaites is stable.

Polar scientist Mathieu Morlighem, who led the study, explains the results.

Why is the Thwaites Glacier so important?

Thwaites Glacier drains a huge area of Antarctica's ice sheet — about 74,000 square miles (192,000 square kilometers), an expanse bigger than Florida. If a snowflake falls within that drainage system, it will eventually end up as part of an iceberg in the ocean off Thwaites.

What we are seeing with Thwaites Glacier right now is a disaster in slow motion.

The bedrock under Thwaites Glacier sits below sea level and slopes downward going inland, so the glacier gets deeper toward the interior of the ice sheet. Once the glacier begins losing more ice than it gains from new snowfall and starts to retreat, it's very hard to slow it down because of this slope. And Thwaites is already retreating at an accelerating rate as the climate warms.

Related: 'We were in disbelief': Antarctica is behaving in a way we've never seen before. Can it recover?

Thwaites Glacier holds enough ice to raise global sea level by more than 2 feet (0.65 meters). Once Thwaites starts to destabilize, it also will destabilize neighboring glaciers. So, what happens to Thwaites affects all of the West Antarctic Ice Sheet, and that affects sea-level rise along coastlines everywhere.

What is marine ice cliff instability?

Marine ice cliff instability is a relatively new concept proposed by scientists in the past decade.

Many of the glaciers around Antarctica have huge floating extensions called ice shelves that buttress the glacier and slow its ice flow into the ocean. With the climate warming, we have seen some of these floating extensions collapse, sometimes very rapidly, in the span of a few weeks or months.

If Thwaites' ice shelf were to collapse, it would expose a very tall ice cliff facing the ocean along its 75-mile (120-kilometer) front. There is only so much force that ice can sustain, so if the cliff is too tall, it will collapse into the ocean.

Once that happens, a new ice cliff farther back would be exposed, and the new cliff would be even taller because it is farther inland. The theory of marine ice cliff instability suggests that if the cliffs collapse quickly enough, that could have a domino effect of ever-higher ice cliffs collapsing one after the other.

However, no one has observed marine ice cliff instability in action. We don't know if it will happen, because a lot depends on how quickly the ice collapses.

What did you discover about the risk to Thwaites?

When the theory of marine ice cliff instability was first introduced, it used a rough approximation of how ice cliffs might collapse once the ice shelf was gone.

Studies since then have determined that ice cliffs won't fail systematically until the ice is about 442 feet (135 meters) high. Even at that point, they would fail more slowly than projected until they became much taller.

We used three high-resolution models to explore what this new physical understanding of ice cliff instability would mean for Thwaites Glacier this century.

Our results show that if Thwaites' entire ice shelf collapsed today, its ice front would not rapidly retreat inland due to marine ice cliff instability alone. Without the ice shelf, the glacier's ice would flow much faster toward the ocean, thinning the front of the glacier. As a result, the ice cliffs wouldn't be as high.

We found that Thwaites would remain fairly stable at least through 2100. We also simulated an ice shelf collapse in 50 years, when the glacier's grounding line — where its grounded ice meets the ocean — would have retreated deeper inland. Even then, we found that marine ice cliff instability alone would not cause a rapid retreat.

The results call into question some recent estimates of just how fast Thwaites might collapse. That includes a worst-case scenario that the Intergovernmental Panel on Climate Change mentioned in its latest assessment report but labeled as "low likelihood."

Thwaites is the glacier everyone is worried about. If you model the entire ice sheet, this is where marine ice cliff instability starts and where it propagates far inland. So, if Thwaites isn't as vulnerable to ice cliff failure as we thought, that's a good sign for the entire ice sheet.

But marine ice cliff instability is only one mechanism of ice loss. This finding doesn't mean Thwaites is stable.

What else is causing glaciers to retreat at an accelerating rate?

There are many processes that make the Antarctic ice sheet unstable, some of them very well understood.

Ice-ocean interactions explain most of the recent ice mass loss so far. Antarctica is a very cold place, so atmospheric warming isn't having a large effect yet. But warm ocean currents are getting under the ice shelves, and they are thinning the ice from below, which weakens the ice shelves. When that happens, the ice streams flow faster because there is less resistance.

Over the past few decades, the Amundsen Sea sector, where Thwaites and Pine Island glaciers are located, has seen an intrusion of warm water from the Antarctic Circumpolar Current, which has been melting the ice from below.

What does climate change have to do with it?

Antarctica can seem like a faraway place, but human activities that warm the planet — such as burning fossil fuels — are having dramatic effects at the poles. Ice loss contributes to sea-level rise, affecting coastal regions around the world.

People's choices today will determine how quickly the water rises.

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

Hundreds of millions of years ago, Earth plunged into a deep-freeze that turned the planet into a giant ball of ice. Now, scientists have discovered rocks marking this moment on a remote archipelago in the Inner Hebrides of Scotland.

The rocks, dating to between 720 million and 662 million years ago, provide a rare complete record of the transition between a warm tropical environment and a "snowball Earth," where glaciers encased the globe.

If confirmed, the Garvellachs rocks could be declared a "golden spike" — a marker showing a transition to a new geological age. Specifically, these rocks would show the point when Earth moved from the Tonian period (1 billion to 720 million years ago) to the Cryogenian period (720 million to 635 million years ago).

"Most areas of the world are missing this remarkable transition because the ancient glaciers scraped and eroded away the rocks underneath, but in Scotland by some miracle the transition can be seen," study first author Elias Rugen, a researcher at University College London's Earth Sciences department, said in a statement.

Scientists believe there were two snowball Earth events during the Cryogenian — the Sturtian glaciation and the Marinoan glaciation. The former event was earlier and more severe, lasting for around 57 million years, while the latter, more poorly constrained event, lasted between 15 and 20 million years.

In a new study, published Thursday (Aug. 15) in the Journal of the Geological Society of London, researchers analyzed layers of rock 0.7 miles (1.1 kilometers) thick, along with another 230-foot-thick (70 meters) layer sitting beneath.

The researchers collected rock samples from two formations on the Garvellachs and analyzed tiny crystals called zircons. Zircons contain uranium, a radioactive element that slowly and steadily decays into lead, so the team was able to determine exactly when the rocks were formed. The researchers found that the lower section of rock formed in tropical waters, when Earth was much warmer.

"These layers record a tropical marine environment with flourishing cyanobacterial life that gradually became cooler, marking the end of a billion years or so of a temperate climate on Earth," Rugen said.

The zircon dating showed the rocks were deposited between 720 million and 662 million years ago — a period that encompassed the transition between the geological periods, from the temperate Tonian and into the Sturtian glaciation and Cryogenian period.

In July, representatives from the International Commission on Stratigraphy, which is part of the International Union of Geological Sciences, went to the Garvellachs to assess whether the site is a geological marker. If it is ratified, the site will be marked with a golden spike.

"The layers of rock exposed on the Garvellachs are globally unique," Rugen said.

Earthquakes are one of the most mysterious and terrifying natural disasters. Although we have some idea of when the big ones might happen, others can occur seemingly out of nowhere, bulldozing cities and creating secondary disasters such as fires, landslides and tsunamis. Climate change is causing increases in other natural disasters, like wildfires and hurricanes. So could it make earthquakes more common, too? 

The biggest and most dangerous type of earthquake is the tectonic earthquake. These earthquakes occur because of tectonic plates, the massive slabs of rock that make up Earth's crust and upper mantle. Heat emanating from deep within the planet causes these plates to move an average of half an inch (1.5 centimeters) per year, making them rub up against each other. The pressure in those areas builds until it reaches a breaking point where the plates will move suddenly, releasing energy that causes earthquakes. 

Unlike with other disasters, it's almost impossible to predict when earthquakes will happen, making planned evacuations next to impossible. 

Unfortunately, climate change could make quakes happen closer together and with more intensity, experts told Live Science. With global warming, glaciers are melting at an increased rate. When melted glacier water flows off land and into the sea, the land that used to sit underneath it rises, said John Cassidy, an earthquake seismologist at the Geological Survey of Canada and the University of Victoria. 

It's the same principle as when a child pushes a pool noodle below the surface and then lets go: The noodle stays down as long as there's pressure from above, but as soon as that pressure is released, it rises back up. When this happens, pressure differences can cause faults that previously lay dormant to suddenly go off, causing earthquakes, Cassidy told Live Science. 

Related: How big is the largest possible earthquake?

More concerning than glacial-melt earthquakes are those that could be caused by an increase in sea level. As sea levels rise, pressure underwater on the seafloor also goes up, said Marco Bohnhoff, a geophysicist at GFZ Helmholtz Centre Potsdam and Free University Berlin in Germany. As water pressure spikes, the pressure on fault lines near the coast will also increase. 

"Several earthquakes are late in their seismic cycle," Bohnhoff told Live Science, including earthquakes predicted to happen near San Francisco and Los Angeles in the next few decades. "That means just a little increase in pressure is enough to advance the seismic clock. It might be enough in many places to trigger earthquakes." 

Even if we stopped using greenhouse gases now, it would take up to 1,000 years for sea level rise to stop, Bohnhoff added. He predicts that over that time, the gaps between big coastal earthquakes will become shorter.

Because proving this prediction would take centuries, Bohnhoff's research is based mostly off of existing models. For example, scientists modeled increases and decreases in the water level of the Salton Sea, an inland body of water about 80 miles (130 kilometers) northeast of San Diego, over the past 1,000 years, and found that when the lake was full, more earthquakes happened along the nearby San Andreas fault. 

Cassidy, however, is uncertain whether sea level rise would cause enough of a pressure change to make these giant quakes happen faster, at least within our lifetimes. He emphasized that when they do happen, climate change will make them more dangerous. Tsunamis triggered by earthquakes will reach farther inland as the sea level rises. Warmer oceans will lead to increased rainfall, which will raise the risk of earthquake-induced landslides. Rainfall will also make earthquake shaking more pronounced, since any vibration in wet ground is far more amplified than in dry ground. But again, we won't know exactly what will happen until it happens, and according to Cassidy there's still a lot we have to figure out.

"It's an important topic, and one that I'm sure we'll see a lot of information coming out on in the coming months and years," he said. "But no matter what we've discovered, it's not good news."

Water covers nearly three-quarters of Earth's surface. But how much water lies hidden underground in the planet's crust?

A 2021 study in the journal Geophysical Research Letters found that more of Earth's water is held underground in the soil or in pores in rock — known as groundwater — than in Earth's ice caps and glaciers.

"There are approximately 43.9 million cubic kilometers [10.5 million cubic miles] of water in the Earth's crust," Grant Ferguson, a hydrogeologist at the University of Saskatchewan and lead author of the 2021 study, told Live Science.

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

In comparison, ice in Antarctica holds about 6.5 million cubic miles (27 million cubic km) of water; in Greenland, about 720,000 cubic miles (3 million cubic km); and in glaciers outside of Antarctica and Greenland, 38,000 cubic miles (158,000 cubic km), the 2021 study noted.

Earth's oceans remain the planet's largest reservoir of water, holding about 312 million cubic miles (1.3 billion cubic km), according to the 2021 study. Still, aside from the oceans, groundwater is the largest reservoir of water globally, the study noted.

A 2015 study in the journal Nature Geoscience had estimated there were 5.4 million cubic miles (22.6 million cubic km) of shallow groundwater — water in the upper 1.2 miles (2 kilometers) of Earth's crust. In contrast, the 2021 study considered groundwater within the upper 6.2 miles (10 km) of Earth's crust, Ferguson said.

This discrepancy was due to how previous estimates of deep groundwater — that below the upper 1.2 miles of Earth's crust — focused only on crystalline rocks with low porosity, such as granite. The 2021 study included sedimentary rocks, which are more porous than crystalline rocks.

All in all, the 2021 study more than doubled the amount of groundwater thought to exist 1.2 to 6.2 miles beneath Earth's surface — from about 2 million cubic miles (8.5 million cubic km) to 4.9 million cubic miles (20.3 million cubic km). This new estimate is nearly as large as the 5.7 million cubic miles (23.6 million cubic km) they calculated for shallow groundwater.

Ferguson noted that the crust is typically 19 to 31 miles (30 to 50 km) thick — significantly thicker than the 6.2-mile depth the 2021 study considered. They focused on the upper crust because it is relatively brittle and so possesses fractured rock that can, in turn, hold water. Below about 6.2 miles, the crust becomes much less porous and likely to contain water, he said.

Shallow aquifers of groundwater, which are mostly fresh water, are used for drinking and irrigation. In contrast, deep groundwater is salty and cannot easily circulate or flow to the surface, largely cutting it off from the rest of the planet's water, Ferguson noted.

However, the relative isolation of deep groundwater means that, in some places, this brine has been trapped for extraordinarily long spans of time. This means it could offer valuable insight into Earth's past, the 2021 study noted.

"We know very little about these waters at depths greater than a few kilometers, making it a frontier area for science," Ferguson said.

In addition, these ancient waters may support microbial ecosystems that are still active today. Such deep biological communities may shed light on how life evolved on our planet and how it might develop on other worlds that likely host water deep beneath their surfaces.

"There's so much more to explore about water at kilometers' depth on Earth and other planets," Jennifer McIntosh, a hydrogeochemist at the University of Arizona in Tucson and co-author of the 2021 study, told Live Science.

The flow of glaciers off the edges of Greenland is causing the landmass to rise like a decompressing mattress.

The uplift of Greenland is a long-term and well-known process. Since the end of the last ice age about 11,700 years ago, the retreat of the ice sheet has taken a weight off of Greenland, allowing its bedrock to rise — a process known as glacial isostatic rebound.

On top of this long-running process, Greenland is now losing ice due to modern-day climate change. The Greenland Ice Sheet is shedding approximately 262 gigatons of ice each year. Its peripheral glaciers, the ice rivers found at the coastline flowing into the sea, are losing about 42 gigatons of ice alone, according to 2022 research.

Now, a new study published Jan. 13 in the journal Geophysical Research Letters finds that this glacial ice loss contributes a significant amount to the springing up of Greenland's bedrock. In some areas, the glacial ice loss is responsible for nearly a third of the total vertical land motion.

"The maximum land uplift is where you have the most mass loss, and that's closest to the biggest glaciers in Greenland," said Danjal Longfors Berg, a doctoral student at the Technical University of Denmark.

Related: Massive asteroid hit Greenland when it was a lush rainforest, under-ice crater shows

Berg and his team used data from 58 GPS monitors drilled into the bedrock around Greenland to measure vertical motion since 2007. Then, they determined how much of this movement was due to current and recent ice loss and how much was from longer-term rebound.

The results showed that ice loss from glaciers was responsible for large portions of Greenland's rise — 32% and 27.9% of the total rebound in two drainage basins in the northern and eastern parts of the landmass. The largest rate of bedrock rebound was seen near Kangerlussuaq Glacier in southeast Greenland, where the ground is rising at about 0.3 inch (8 millimeters) per year. That glacier has retreated 6.2 miles (10 kilometers) since 1900 and has thinned near its terminus by hundreds of meters.

Having a good grasp on the rise of Greenland's bedrock is a complementary way to measure the region's ice loss, Berg told Live Science. Other ways of quantifying the shrinking of the Greenland Ice Sheet include measurements of altimetry, or the height of the ground, and gravity, variations of which can be measured by satellite. Together with vertical land motion, these multiple techniques can lead to precise measurements of how much ice is disappearing, Berg said.

"When we estimate how much mass it's losing," he said, "then we can give a better estimate of how much the sea level is rising."

Planetary scientists have discovered salty glaciers near the north pole of Mercury, raising the possibility that the closest planet to the sun may be capable of hosting life. The new findings, which were made using past observations from NASA's retired MESSENGER probe, were published in The Planetary Science Journal in November.

"Our finding complements other recent research showing that Pluto has nitrogen glaciers, implying that the glaciation phenomenon extends from the hottest to the coldest confines within our Solar System," lead study author Alexis Rodriguez, a planetary scientist at the Arizona-based nonprofit Planetary Science Institute (PSI), said in a statement.

These glaciers, found in Mercury's Raditladi and Eminescu craters, aren't quite like the typical icebergs we think of on Earth. Instead, they're flows of salt that trapped volatile compounds deep below Mercury's surface. In geology terms, volatiles are chemicals that readily evaporate on a planet — like water, carbon dioxide and nitrogen. Mercury's strange salt-bergs were revealed by asteroid impacts, which exposed this material trapped below the surface; that's why scientists discovered them in craters.

Glaciers are surprising to find on Mercury because of its proximity to the sun; the planet is 2.5 times closer to our star than Earth is. At that small distance, things are a lot hotter. Yet, these salt flows could have preserved their volatiles for "over one billion years," according to study co-author Bryan Travis, also a planetary scientist at PSI.

Although Mercury's salty deposits aren't analogous to typical icebergs or Arctic glaciers, similarly salty environments do exist on Earth, so geologists have a good idea of what these environments are like — and whether life can emerge there.

"Specific salt compounds on Earth create habitable niches even in some of the harshest environments where they occur, such as the arid Atacama Desert in Chile," Rodriguez said. "This line of thinking leads us to ponder the possibility of subsurface areas on Mercury that might be more hospitable than its harsh surface."

With volatiles — which are necessary for life, especially water — trapped underground, Mercury might be able to sustain subterranean life sheltered from the harsh rays of the sun. Just as planetary systems have "Goldilocks zones" — regions around their star where liquid water can persist — might have a similar "potentially habitable" region below its surface, the researchers suggested. And if Mercury could host life, then exoplanets similar to Mercury might become more enticing to scientists who are hunting for alien life.

The discovery of these glaciers also helps to explain a long-standing mystery about Mercury: craters with chunks missing. The researchers propose that the little pits observed dotting some craters used to be filled with volatiles, before the impact exposed them and they evaporated.

One big question remains: How did the volatile layers get there in the first place? Observations of Mercury's north pole suggest the volatiles were deposited on top of a fully formed landscape. Rodriguez suggested they could come from "the collapse of a fleeting, hot primordial atmosphere early in Mercury's history."

Alternatively, maybe Mercury had lakes, co-author Jeffrey Kargel, also at PSI, proposed. Perhaps "a dense, highly salty steam" leaked out of the volcanic interior of young Mercury and then evaporated, leaving the salt behind, he said.

Further studies are needed to truly shine a light on what may lurk below Mercury's surface.

Devastating volcanic eruptions may have been so enormous they turned the planet into "Snowball Earth" 717 million years ago, a study has found.

The volcanic outburst — one of the largest in Earth's history — likely triggered a series of chemical reactions that sucked carbon dioxide (CO2) from Earth's ancient atmosphere.

The massive eruptions, which occurred in what is now northern Canada, spewed cascades of lava that hardened into a volcanic highland covering 860,000 square miles (2.23 million square kilometers) — an area three times the size of Texas. Acidic rain then pelted these fresh rocks, producing a chemical reaction that may have enveloped the planet in ice for 57 million years.

Researchers already suspected that volcanic activity may have caused this glaciation episode, known as the Sturtian glaciation. But they were unsure exactly how the outburst caused the onset of Snowball Earth.

"Nothing can be understood in isolation," Galen Pippa Halverson, a professor of geology at McGill University in Canada and co-author of the new study, told Science.

Related: World's oldest glacier dates to 2.9 billion years ago, research finds 

There are two main ways that volcanic eruptions can cool the planet down, according to the study published 27 June in the journal Earth and Planetary Science Letters. Outbursts release gasses containing sulfur-rich particles that become suspended in the atmosphere and block sunlight, resulting in cooling. Eruptions may also alter the climate via a chemical reaction known as weathering, which lava rocks are particularly susceptible to. 

Weathering occurs when rainwater — which is slightly acidic due to dissolved carbon dioxide (CO2) — reacts with the minerals in rocks to form clays and soluble salts. In forming these new minerals, CO2 is sucked out of the atmosphere and trapped in sediments that eventually wash into the ocean. The removal of CO2, a greenhouse gas, leads to global cooling. 

To understand which mechanism triggered the Sturtian glaciation, the team needed to home in on exactly when the volcanic outburst took place. Sulfur particles stay suspended in the atmosphere for months to years, whereas rock weathering takes 1 million to 2 million years to spark a global cooling effect.

Halverson and her colleagues analyzed tiny crystals in the rocks coughed up by volcanoes in the area, which is known as the Franklin large igneous province (LIP). They measured the ratios of uranium and lead in these crystals and calculated their age based on the rate of decay. The team also dated rocks that had been scoured by glaciers as Earth froze over.

Their analysis suggests the volcanic outburst took place 1 million to 2 million years before the glaciation, pointing to chemical weathering as the primary cause of Earth's cooling. Another study, published in November 2022 in the journal Science Advances, came to the same conclusion.

Rock weathering elsewhere on the globe may have contributed to the Franklin LIP's cooling effect. The eruptions and subsequent glaciation occurred at a time when Earth's continents formed one giant landmass around the equator — the ancient supercontinent Rodinia. This tropical landmass was frequently battered with rain, resulting in additional weathering and CO2 entrapment.

But some experts remain skeptical. Paul Hoffman, an emeritus professor of geology at Harvard University who co-authored the 2022 study, said the timing of the Sturtian glaciation is still debated and may not match the newly pinpointed timing of the Franklin LIP. Ice-scoured rocks that represent the start of Snowball Earth may have formed much later than currently thought, because the erosion indicates that thick ice was flowing at sea level — a process likely to have begun several hundred thousand years after the oceans froze over, Hoffman told Science. 

Nearly 10,000 years ago, Earth came out of its most recent ice age. Vast, icy swaths of land around the poles thawed, melting the glaciers that had covered them for nearly 100,000 years. 

Why, after such a long period of cold, did the ice age finally come to an end? Scientists are still searching for the answer.

"One of the big questions in my research field right now is why the last ice age ended," Brenda Hall, a glacial geologist and professor of Earth and climate sciences at the University of Maine, told Live Science.

Hall said that the traditional explanation — and short answer — for why ice ages begin and end is a series of eccentricities and wobbles in the planet's orbit known as the Milankovitch cycles. Named after Serbian scientist Milutin Milankovitch, these cycles describe patterns in Earth's orbit and axial tilt. Over time, our planet's orbit around the sun alternates from being more circular to more egg-shaped. At the same time, our planet's axis tends to both tilt and wobble. 

Milankovitch found that these factors combine at regular intervals to cause land at 65 degrees north latitude (a parallel that runs through Canada, Alaska and parts of Eurasia) to become warmer than normal and theorized that this warming and then subsequent cooling of the Northern Hemisphere explained the planet's cycle of ice ages — or glacials — and warmer periods — or interglacials.

"Quite simply, we can say that ice ages line up with these Milankovitch oscillations," Hall said. "But we don't know exactly why."

Related: Why does the Earth rotate?

However, while there is evidence that Milankovitch cycles drive the ebb and flow of ice ages, many modern glaciologists don't think the cycles' reported ties to ice ages completely checks out. One issue is that when the glaciers in the Northern Hemisphere melted, glaciers in the Southern Hemisphere melted too. But with the traditional explanation, it's unclear how warming in one hemisphere would melt glaciers in the other — especially when, according to Hall, the Milankovich-driven changes in sunlight intensity that would produce warmer temperatures in the north would cause temperature drops in the south, counterbalancing any net warming.

In recent years, glaciologists have attempted to fill in the gaps between what we know about Milankovitch cycles and Earth's ice ages. Hall said that the missing link needs to explain how these cycles cool and warm the entire planet at once, not just one hemisphere at a time. 

"There has to be some way to get the whole globe to actually warm up at once," Hall said. 

One possible explanation is that when the Northern Hemisphere began to warm around 13,000 years ago, meltwater and icebergs flooded the North Atlantic Ocean, causing a temporary cooling of the Northern Hemisphere known as the Younger Dryas period (12,900 to 11,700 years ago). There is some evidence that the Younger Dryas affected ocean currents in a way that caused the Southern Atlantic to warm up, stirring up the ocean in the process and releasing tons of stored carbon dioxide into the atmosphere, which in turn caused glaciers in the Southern Hemisphere to melt over the next 1,500 years. The end result was likely a more carbon-rich atmosphere that continued to warm both hemispheres, lifting the planet out of the glacial period.

Another hypothesis, published in 2021, suggests that the length and intensity of the Southern Hemisphere's winters could dictate when ice ages end. On the surface, it sounds like the polar opposite of the Milankovitch theory, which suggests that Northern Hemispheric summers drive the climatic changes. However, long winters in the Southern Hemisphere alter wind patterns near the tropics, which can create frequent storms over an area of the Pacific Ocean known as the Tropical Warm Pool — a region of ocean that stores and releases great amounts of heat. Altered winds can create storms in this area, which in turn releases massive amounts of water vapor that can act as a greenhouse gas.

Another idea is that salty water pouring from the Indian Ocean into the Atlantic Ocean helped end the last ice age. The Indian Ocean had become super salty because a drop in sea level had cut off a critical current that flows from the Pacific to the Indian Ocean; normally, this current diluted the Indian's very salty tropical waters. A change in wind patterns and currents in the Indian Ocean could have caused the Indian Ocean to dump tons of dense, salty water into the Atlantic Ocean, altering its currents and temperatures in both the Northern and Southern hemispheres. 

More evidence is needed to know for sure if any of these hypotheses can actually explain why the last ice age ended. But glaciologists are continuing to look into this cold case. 

Europe's glaciers and ice patches are a treasure-trove of ancient artifacts that show how civilizations and technology have changed over thousands of years. 

"The archaeological finds from the ice are a tiny silver lining to global warming," archaeologist Lars Pilø, who heads the Secrets of the Ice project in the mountainous Oppland region of central Norway, told Live Science. 'The retreating ice has revealed itself to be an enormous deep freezer."

Here are 25 of the most fascinating objects revealed by Europe's melting ice.

1. Iron Age sandal

The discovery of a humble sandal, preserved in a mountain pass in central Norway, suggests that the area where it was found was a route for travelers about 1,700 years ago. This likely means that at the time the footwear was worn, there was less snow and ice there than there is now. Radiocarbon dating shows the sandal was made in about A.D. 300, and its style is similar to Roman sandals from that time.

2. Viking sword

This iron sword was found by hunters on a mountain slope in Norway, at more than 5,250 feet (1,600 meters) above sea level. There's no sign of a burial nearby and there’s seemingly no reason to have swords in such a location, so archaeologists think that its owner may have gotten lost.

3. Viking Age mitten

This left-handed mitten was found in the Lendbreen pass over the Lomseggen mountain ridge near the village of Lom in central Norway, which has been the site of many important finds. It was made from patches of several different textiles in about A.D. 900, during the Viking Age.

4. Medieval horseshoe

This horseshoe was also found at the Lendbreen pass and dates from about the 12th or 13th century. Researchers think it came from a packhorse, as horse dung and horse bones were discovered nearby. The date of the find, hundreds of years later than the sandal or mitten, suggests Lendbreen was used by travelers for hundreds of years. But the remote pass is almost never used today.

5. Giant slingshots?

What seemed to be giant slingshots started melting out of the ice in 2011. Radiocarbon dating shows this one was made in about A.D. 400; it is over 3 feet (1 m) long, and has cuts made by a knife. Some are even larger. Archaeologists were bewildered by these objects until one of their team recognized them as “tång” or “pliers” for strapping down the load on sledges when transporting hay or leaves for animal fodder. Hay-sledges with tång were still in use in the area until the 1950s, when tractors became common.

6. Wooden peg

A few remote buildings once existed near Lendbreen, but none survive. This finely carved wooden peg was found in the timbers of an old farmhouse, possibly from the 19th century, but its purpose wasn't known until recently. "It is easy to think that our high mountains were remote and isolated regions in the past," Pilø said. "However, our finds show the ancient mountain people were well connected to the outside world. They sold products such as reindeer antler and pelts and imported commodities that they could not access locally, such as salt and grain."

7. Another wooden peg

Archaeologists later found another wooden peg of almost exactly the same design that had melted out of the Lendbreen ice patch. The purpose of these pegs was unknown, and this one was exhibited at a local museum, where an elderly woman finally solved the mystery: they were bits for kid goats or lambs to stop them suckling their mothers so that people could use the milk. She said she had used them in the 1930s; this one dates from the 11th century.

8. Medieval candle box

This wooden box sealed with a lid was found on the surface of the Lendbreen ice patch near the top of the pass. It was filled with a mysterious substance that turned out to be beeswax, and archaeologists think it once held a large candle. Candle boxes like these were used until recently in Norway to transport candles between summer and winter farm buildings. Radiocarbon dating shows this one is at least 500 years old.

9. Toy arrow

This 10-inch (26 centimeters) toy wooden arrow from about A.D. 600 offers a tantalizing glimpse into childhood at the time. "Was it lost in the snow during practice shooting? The unhappy child probably thought that it was lost forever," he said. But the ice preserved it for 1,400 years. Despite being a child's toy, it had a serious purpose, as hunting was a major source of food. "Mastering bow and arrow could be of life-or-death importance, not least during the time of this little arrow," Pilø said.

10. Real arrows

Reindeer were the main prey of hunters in the icy Norwegian mountains, and iron arrowheads like this one were found near the peak of the Sandgrovskaret mountain, about 50 miles (80 kilometers) northeast of Lendbreen. Archaeologists have seen an uptick in artifacts from the Late Antique Little Ice Age — a period from A.D. 536 to 660 when volcanic eruptions and dust clouds led to cooling global temperatures. "Our finds from the ice actually increase in number during this cold spell, probably because reindeer hunting became more important as agriculture struggled," Pilø said.

11. Iron Age hunting hide

These five arrowheads were found in a rock-built hunting shelter high on the Sandgrovskaret mountain, which was intended to make these Iron Age hunters "invisible" to their prey. Pilø said such hides were important because the primitive arrows were only deadly from about 66 feet (20 m) away, and reindeer are typically very shy of people.

12.  Bronze Age bows, arrows and a lunchbox

The remains of two bows, arrows, and what seems to be a lunchbox from the Bronze Age were found in an Alpine pass in Switzerland. The artifacts were discovered at an altitude of almost 2,700 feet (8,800 m) beneath a rock shelter beside a glacier. They were likely left there by hunters or herders about 4,000 years ago. The ancient "lunchbox" is made from wood and once contained a roughly ground flour made from wheat, rye, barley and spelt.

13. Otzi the Iceman

One of the most famous discoveries that melted from Europe's mountain ice is the body and kit of Ötzi the Iceman, who died 5,300 years ago in an Alpine pass between modern-day Italy and Austria. Near Ötzi's remains, archaeologists found the remains of an ax with a copper blade, an unfinished bow, plant fiber, animal hides and pieces of leather. A severe wound from an arrowhead lodged in Ötzi's shoulder and a deep cut in his hand — thought to be a defensive injury — suggest he may have been ambushed.

14. Mummified couple

Ötzi is one of the oldest finds in the Alps, but relatively modern remains are also preserved in the ice. In 2017, the mummified bodies of a Swiss couple were found by a ski-lift technician near the Tsanfleuron glacier in the western Bernese Alps, after they'd been missing for 75 years. In August 1942, Marcelin and Francine Dumoulin had left their house in the mountain village of Chandolin to feed their cattle in a nearby pasture,but were never seen alive again. It's thought they fell into a crevasse on the glacier during bad weather.

15. WWII-era airplane

Glaciers can also preserve relatively modern objects — such as this aircraft from just after World War II, which was found by hikers in 2012. Archaeologists determined the wreck is a C-53 Skytrooper Dakota, an American military transport plane that crashed in bad weather in the Swiss Alps in 1946 after taking off from Vienna in Austria, bound for Pisa in Italy.

16. WWI battlefield

Relics of the earlier war litter the Alps between Italy and Austria where the Guerra Bianca — the "White War" — was fought between 1915 and 1918. The border between the Kingdom of Italy and the Austro-Hungarian Empire at the time was high in the mountains, and combatants had to contend with freezing temperatures, ice and heavy snow. The remains of those killed in the fighting are still melting out of the glaciers in the region, along with artifacts like rifles, gas masks and glasses.

17. Bronze Age shell arrowheads

"With ice melting from anthropogenic climate change, these objects awaken from a long sleep and so does the history they carry," Pilø said. But the clock starts ticking once the artifacts are out in the open: "Exposure breaks down the artifacts and the sooner we can find them, the better it is," he said. These 3,500 year-old arrows have arrowheads made from the shells of freshwater mussels, probably from Norway's lowlands — something not seen anywhere else in the world. The Secrets of the Ice team have found three such arrows in ice in central Norway, and others from the same time period have also been found.

18. Pair of Iron Age skis

In 2014, the Secrets of the Ice team found a single Iron Age ski at the Digervarden ice patch in southern Norway's Reinheimen National Park — and they then found the other one a few meters away, but seven years later. They're made of wood, and both are remarkably well preserved, including the bindings that used to secure them to the skier's feet. "The new ski is even better preserved than the first one!" Pilø wrote in a blog post. "It is an unbelievable find."

19. Iron Age horse snowshoe

This snowshoe for a horse was found on Norway's Lendbreen ice patch in 2019. Its stunning preservation makes it seem as if it was lost recently, but radiocarbon dating shows it was made in the third century A.D. Archaeologists say this must have been at the beginning of the use of the Lendbreen Pass by travelers, and so the unlucky packhorse that lost its shoe was probably one of the first animals to cross the ice patch.

20. Norse sledge

The remains of a wooden sledge were found not far from the site where archaeologists uncovered the two Iron Age skis. It, too, likely dates from the late Iron Age, about 1300 years ago. "Finds of skis and sleds show that people traversed the high mountains even in the wintertime, with all the risks this involved," Pilø said.

21. Bronze Age bootie

"One of the most important lessons we have learned from the artifacts melting out of the ice is that humans used the high mountains much more intensively than previously thought," Pilø told Live Science. Dated to around 1100 B.C., this 3,000-year-old bootie is the oldest shoe ever found in Norway and one of the prized finds by the Secrets of the Ice team. The bootie is made from leather and probably belonged to a woman or a young man.

22. Iron Age tunic

This woven woolen tunic dates from about A.D. 300, during the late Iron Age and is the oldest complete piece of clothing ever found in Norway. It was discovered crumpled in a ball near the upper edge of the Lendbreen ice patch in 2011. It was heavily worn; patches show it was repaired several times, and the person who left it behind may not have been its first owner. The archaeologists at Secrets of the Ice think it was worn by a reindeer hunter who may have combined it with a waterproof outer layer.

23. Medieval walking stick

This 1,000-year-old walking stick found at Lendbreen is inscribed with runes that read "Owned by Joar," who hopefully made his way across the pass without it. "Glacial archaeological fieldwork can be quite challenging — it is very different from archaeology in the lowlands,' Pilø said. "There are a lot of logistics that need to be solved, such as tents, packhorses and food." What's more, the "weather can put a stop to all activities on short notice."

24. Viking spear

This iron spearhead and its wooden shaft were found on the Lendbreen ice patch in 1974; although the shaft had separated from the spearhead, the wood  was so well preserved that the finder carried it down by hand. Analysis shows it dates from between A.D. 825 and 950, during the Viking Age. The wooden shaft was bent by the pressure of the snow when it was found, but the entire spear once measured over 7 feet (230 cm). The type of spearhead and the build-quality of the spear suggests it was a weapon for combat, rather than for hunting, and so it may have been lost in the pass by a Viking warrior on his travels; but archaeologists think it may also have been lost by a reindeer hunter.

25. Viking Age distaff

One of the most recent finds at Lendbreen is this ornately carved distaff — a device for holding wool while spinning it from fibers. It dates from the Viking Age, which was roughly from A.D. 800 until 1066. Household items like this are treasures for archaeologists, who can use them to reconstruct everyday lives and understand more about regional economies. But the artifacts are threatened. "Most of the ice in the high mountains in Scandinavia and the Alps is going to melt away this century, even with a rapid decline in greenhouse gas emissions," Pilø said. "The melt is already locked in. This is something that is hard to process, both intellectually and emotionally."

The amount of sea ice surrounding Antarctica has reached its lowest level since modern records began, for the second year in a row. 

Sea ice is frozen seawater that floats on the ocean's surface around the planet's polar regions. It forms at much lower sustained temperatures than freshwater ice does, at around 28.8 degrees Fahrenheit (minus 1.8 degrees Celsius). Sea ice builds up during the winter until it reaches its maximum extent, and then melts away in the spring and summer until it reaches its minimum extent.

In Antarctica, where summer and winter are flipped relative to the Northern Hemisphere, sea ice normally reaches its maximum extent in September, when sea ice covers around 7 million square miles (18.5 million square kilometers). At its minimum extent, at the end of February, historically only around 1 million square miles (2.5 million square km) remains, according to the National Snow and Ice Data Center (NSIDC), based at the University of Colorado Boulder (UCB).

Last year, the minimum sea ice extent was less than 772,000 square miles (2 million square km), the lowest total since scientists began recording sea ice extent with satellites in 1979. On Feb. 21 this year, that number had shrunk to just 691,000 square miles (1.8 million square km), which is roughly 40%  less than the average between 1981 and 2010, NSIDC reported. 

Related: Melting sea ice could wipe out 98% of emperor penguins by the end of the century 

The record-breaking minimum was expected after an extraordinarily hot January, which was the seventh warmest since records began 174 years ago, according to the National Oceanic and Atmospheric Administration.

"By the end of January, we could tell it was only a matter of time [until the record was broken]," Will Hobbs, an Antarctic sea ice expert at the University of Tasmania and the Australian Antarctic Program Partnership, told The Guardian. "It wasn't even a close run thing."

Antarctica's minimum sea ice extent will likely continue to decrease in the coming decades as global temperatures rise as a result of human-caused climate change and more multiyear ice, which acts as a seed for new ice growth, melts away.

Why is sea ice important? 

Sea ice is crucial for polar predators, such as penguins in Antarctica and polar bears in the Arctic, which use the ice as a platform for hunting. But the sea ice also helps stabilize ice on Antarctica. 

"Lower sea ice extent means that ocean waves will pound the coast of the giant ice sheet, further reducing ice shelves around Antarctica," Ted Scambos, a senior research scientist at the Cooperative Institute for Research in Environmental Sciences based at UCB, said in a statement.

Ice shelf instability could, in turn, threaten massive glaciers, such as the Pine Island and Thwaites glaciers. The latter is commonly known as the Doomsday Glacier, which, despite melting at a slightly slower rate than previously expected, is still teetering perilously close to disaster. 

"If these glaciers begin a more rapid runaway loss of land ice, it could trigger a dramatic increase in sea level rise rates before the end of this century," Julienne Stroeve, an NSIDC senior research scientist and professor at the University of Manitoba in Canada, said in the statement.

Sea ice also reflects sunlight back into space, which helps to cool Earth. Lower sea ice levels reduce  the portion of light reflected, called albedo, which will further increase global warming.

During the last ice age, the coastal route from Asia to North America was so treacherous, humans likely crossed over only during two time windows, when environmental factors were more favorable for the long and dangerous journey, a new study finds.

The first window lasted from 24,500 to 22,000 years ago, and the other spanned from 16,400 to 14,800 years ago, according to the study, published Feb. 6 in the journal Proceedings of the National Academy of Sciences.

During these periods, winter sea ice cover and sea ice-free summers would have likely given these travelers access to a diverse marine buffet, as well as ways to safely travel along the North Pacific coast, the researchers said.

There are two main scenarios explaining how people may have first migrated to the New World. The older idea suggested that people made this journey on land when Beringia — the land bridge that once connected Asia with North America — was relatively ice-free. However, a growing body of evidence suggests that travelers used watercraft along the Pacific coasts of Asia, Beringia and North America before 15,000 years ago, when giant ice sheets would have made an overland journey extraordinarily difficult.

To see how viable the coastal route may have been for migration at different times, scientists analyzed how changes in climate over the past 45,000 years might have influenced sea ice, glacier extent, ocean current strength, and food supplies on land and sea.

Related: These first Americans vanished without a trace — but hints of them linger

The researchers developed climate models based on new data on sea ice variations and previously collected sediment samples from the Gulf of Alaska holding details about sea ice, sea surface temperatures, salinity and debris carried on ice. Their models revealed the two time windows — the first 2,500-year-long window and the second 1,600-year-long span — for year-round coastal migration, which would have enabled a favorable coastal route when the inland route was blocked. 

During those two windows, summer kelp forests would have helped keep travelers fed. Sea ice during the winter during those periods also may have supported migration; when stuck on the shoreline, sea ice can be relatively flat and stable, so ancient hunters could have walked on it and captured seals, whales and other prey to survive those winters, the researchers noted.

"Rather than being an obstacle, we suggest that sea ice may have partly facilitated movement and subsistence in this region," study first author Summer Praetorius, a paleoceanographer at the U.S. Geological Survey, in Menlo Park, California, told Live Science.

Other times during the past 45,000 years were likely less friendly to coastal migration. For instance, a giant pulse of meltwater drained into the Pacific between about 18,500 and 16,000 years ago; this huge pulse came from the edges of the giant ice sheet that once covered most of northeastern North America, and would have more than doubled the average strength of the northward ocean currents along Alaska. This, in turn, would have made boat travel heading south along the Pacific coast more difficult. The melting glaciers at this time also would have led giant icebergs to regularly calve into the ocean, posing a major hazard to coastal migration.

"At present we know more about the ice-free corridor — the timing of its opening and the timing of when it became viable for human migration," Michael Waters, an archaeologist at Texas A&M University who did not take part in this research, told Live Science. "This paper is a good step in doing the same for the coastal migration route." 

In the future, the researchers would like to "look into how marine ecosystems were changing in response to past climate variations to better understand what resources were available to coastal people at different times," Praetorius said. She also wants to learn more about any brief warming spells a few centuries to millennia long that happened around Beringia, to see if they were linked to specific periods of migration.

"It is becoming clear that people entered the Americas by traversing the coast," Waters said. "They took the coastal migration hypothesis to the next level. Well done."

Antarctica isn't just the coldest continent; it's the one hiding the most secrets. 

Because of its remoteness and forbidding climate, there is still a treasure trove of weird and wonderful oddities beneath the ice and waves just waiting to be discovered. And in 2022, scientists hit the jackpot. From secret ecosystems and ancient DNA to logic-defying blooms and creepy fish nests, here are our top Antarctica stories from this year.

 A "hidden world" under the ice 

Researchers uncovered a never-before-seen ecosystem that lurks in an underground river deep below the icy surface of the Larsen Ice Shelf using a massive hot water drill.

The secret habitat lies in a massive chamber around 1,640 feet (500 meters) below the surface of the ice. Researchers found the underground structure after noticing an unusual groove in a satellite image of the ice sheet, but never expected to find anything inside when they eventually drilled down to investigate it.

Instead, the team found thousands of tiny crustaceans known as amphipods, which had them "jumping up and down for joy."

Read more: Discovery of 'hidden world' under Antarctic ice has scientists 'jumping for joy' 

New deepest point mapped 

A new map of the Southern Ocean gave scientists their most detailed view to date of the seafloor surrounding Antarctica, including its deepest point, the "Factorian Deep."

Resting at a depth of around 24,400 feet (7,437 m) below the sea surface, or 17 Empire State Buildings stacked top to bottom, the Factorian Deep was only discovered in 2019. But, until now, researchers had no idea how it fit together with the surrounding seafloor.

The new map draws from more than 1,200 sonar data sets, collected mostly by science vessels, and covers more than 18.5 million square miles (48 million square kilometers) of seafloor. Researchers hope to use the sea bottom chart to identify underwater mountains, or seamounts, that may be hotspots for marine life.

Read more: 'Factorian Deep,' the new deepest point in Antarctica's Southern Ocean, mapped for the first time

Logic-defying bottom blooms 

Separate teams of researchers discovered seemingly impossible phytoplankton blooms lurking deep beneath the ocean's surface in both of Earth's polar regions. 

Scientists had previously assumed that there was not enough light in the water below polar sea ice for phytoplankton to produce enough energy to survive. But the new studies revealed that the algae can thrive with as little as 1% of the light available at the surface.  

In Antarctica, researchers used deep-diving floats to measure the amount of chlorophyll-a, a pigment used by algae and other plants during photosynthesis, in the water deep beneath sea ice and found that there was likely a high concentration of phytoplankton there.

The researchers suspect that a decrease in the amount and lifespan of sea ice caused by climate change could help sustain these bottom blooms by maximizing the amount of light they receive.

Read more: Logic-defying 'bottom blooms' could sustain hidden ecosystems in Arctic and Antarctica

1 million-year-old DNA unearthed 

Researchers accidentally unearthed DNA from ancient microorganisms, some of which are roughly  1 million years old, while collecting routine seafloor sediment samples in the Scotia Sea. 

The ancient genetic material was pulled up from depths of up to 584 feet (178 m) beneath the seafloor and dates back to between 1 million years ago to around 540,000 years ago. 

Scientists aren’t certain which species the oldest DNA samples belong to, but the most recent samples likely originate from a group of phytoplankton known as diatoms. The diatoms date back to an ancient period of global warming and could provide clues as to how Antarctica's marine ecosystems will respond to human-caused climate change.  

Read more: Scientists discover 1 million-year-old DNA sample lurking beneath Antarctic seafloor

Doomsday glacier in danger 

Underwater robots that peered under Antarctica's Thwaites Glacier, nicknamed the "Doomsday Glacier," saw that it is holding on by its fingernails to the seabed below. Once it detaches, its doom may come sooner than expected due to rapid movement and an extreme spike in ice loss.

A new map of the seafloor surrounding the icy behemoth revealed a series of parallel grooves that were left behind as the glacier scraped along the ocean bottom during previously unknown periods of rapid retreat within the last few centuries.

Researchers warn that this type of rapid melting could be triggered again by extreme warming driven by climate change.

Read more: 'Doomsday Glacier' is teetering even closer to disaster than scientists thought, new seafloor map shows 

Enormous underground river discovered 

Researchers discovered a massive underground river that flows beneath four separate ice masses using ice-penetrating radar mounted on aircraft.  

The river is longer than the Thames in England and drains melting ice from a region the size of France and Germany combined and into the Weddell Sea. If the entire region were to melt as a result of climate change, it could raise global sea levels by 14.1 feet (4.3 m), which could have catastrophic consequences.

Researchers suspect that there is probably an entire system of underground rivers across the continent.

Read more: Enormous river discovered beneath Antarctica is nearly 300 miles long 

World's largest iceberg says farewell 

NASA’s Terra satellite captured a photo of the world's largest iceberg, A-76A, floating in the mouth of the Drake Passage — a turbulent stretch of water in the Southern Ocean — as it began its journey away from Antarctica.

The enormous ice slab is around 84 miles (135 kilometers) long and 16 miles (26 km) wide and first broke off from the Ronne Ice Shelf in 2021.

Normally, when icebergs drift into the Drake Passage they are quickly dragged eastward by strong ocean currents, before being whipped northward into warmer waters, where they completely melt soon after.

It is unclear where A-76A will eventually end up or when it will meet its watery grave.

Read more: World’s largest iceberg is getting swept away from Antarctica to its doom, satellite image shows 

Millions of fish nests 

Scientists onboard an icebreaker ship in Antarctica were blown away when they spied a trove of 60 million icefish nests dotting the floor of the Weddell Sea.

The nests were serendipitously discovered using a seafloor video feed onboard a scientific vessel that was primarily looking to study whales. The nests were 10 inches (25 centimeters) apart and covered an area of around 93 square miles (240 square km). A parent fish stood guard atop each nest, which contained an average of 1,700 eggs each.

The area was also littered with icefish carcasses, suggesting that this massive icefish colony is an integral part of the local ecosystem, most likely serving as prey for Weddell seals.

Read more: Largest fish nursery discovered beneath Weddell Sea in Antarctica 

Massive lake under the ice 

Researchers discovered a city-size lake hidden deep underneath the East Antarctic Ice Sheet.

The hidden lake, which was named Lake Snow Eagle, has a surface area of 143 square miles (370 square km) and lies in a mile-deep canyon beneath 2 miles (3.2 km) of ice.

The team uncovered the lake following three years of exhaustive aerial surveys over the ice sheet, using radar and special sensors designed to measure minuscule changes in Earth's gravity.

Experts believe it could contain 34 million-year-old river sediments that are older than the ice sheet itself and could shed light on what Antarctica was like before the continent froze.

Read more: City-size lake found miles below Antarctica's biggest ice sheet 

Simultaneous polar heat waves 

This year, both of Earth's polar regions experienced unprecedented, simultaneous heat waves that saw temperatures briefly skyrocket to never-before-seen heights in some areas.

In Antarctica, the average temperature was 8.6 degrees Fahrenheit (4.8 degrees Celsius) warmer than average. On the same day, the average temperature in the Arctic was 6 F (3.3 C) higher than normal.

It is very uncommon to see high temperatures across both polar regions at the same time because they have contrasting seasons; as spring arrives in the Northern Hemisphere, the Arctic is just starting to thaw while Antarctica is beginning to freeze after months of summer melt.

Scientists were particularly surprised by the heat wave in Antarctica because temperatures there have remained more stable overall compared to the Arctic.

Read more: Alarming heat waves hit Arctic and Antarctica at the same time

Looking to fill your boots with even more Antarctica content? This year we also answered mysteries such as when Antarctica first became a continent, why no polar bears live there and whether it will ever be habitable to humans. 

The ancient, mummified body of Ötzi the Iceman was found decades ago by hikers in the high Alps — but how did it get there? A new study questions the prevailing story of Ötzi's death more than 5,000 years ago, suggesting that Ötzi did not die in the gully where he was found. Rather, his remains may have been carried there by the periodic thawing of the ice that surrounded his body.

And researchers propose that other prehistoric people who died in icy, mountainous regions could have been preserved by the same process.

"I think the possibility now is perhaps a bit larger" of finding another prehistoric body, archaeologist Lars Pilø told Live Science. "It’s not so large that I can promise there will be a body in the next decade, but I think that there’s definitely a chance."

Related: 30 amazing facial reconstructions, from stone age shamans to King Tut's father

Pilø is the lead author of the new study, published Nov. 7 in the journal Holocene, which takes a fresh look at evidence from Ötzi. He also leads the Secrets of the Ice project, which is associated with Norway’s Innlandet County Council and the Museum of Cultural History at the University of Oslo; it studies the archaeology of glaciers and ice patches, many of which are now melting and revealing frozen troves of ancient artifacts.

The iceman cometh

The remains of Ötzi, who’s named after the Ötztal Alps where he was found, were discovered on Sept. 19, 1991 by German tourists in an Alpine pass between Italy and Austria.

The hikers first thought they’d found the preserved body of a modern mountaineer, but investigations later determined that Ötzi died about 5,300 years ago.

According to the Secrets of the Ice website, the generally accepted story of Ötzi’s death comes from investigations by archaeologist Konrad Spindler of the University of Innsbruck in Austria.  

Spindler found that Ötzi had probably been murdered: an arrowhead was embedded in his shoulder, and a deep cut in his hand appeared to be a defensive wound suffered while warding off a blow. He also noted that Ötzi’s backpack, bow and arrow quiver were damaged, which Spindler proposed was a sign of combat.

But Pilø and his colleagues argue that the damage to Ötzi’s equipment was probably caused by the pressure of the ice that surrounded them.

"There’s definitely been a conflict," he said. "But what we say is that the damage to the artifacts is more easily explained by natural processes."

Alpine death 

The most significant proposal in the new study is that Ötzi didn’t die at the bottom of the gully where he was found, but rather that his body was carried there as the ice thawed and refroze over several summers.

Early investigations proposed that Ötzi was killed in the gully in the fall season, and that his body was protected there from the crushing pressure of a glacier above.

But analysis of the food in Ötzi’s intestine suggests instead that he died in the spring or early summer, when the gully would have been filled with ice, Pilø said.

In the new study, the authors propose that Ötzi died somewhere on the surface of a stationary ice patch — not a moving glacier — and that his remains and artifacts were carried into the gully by the periodic thawing and refreezing of the ice.

That means the body and artifacts were exposed at times, and may have been submerged in melted ice water, but they nonetheless stood the test of time for thousands of years. So, it’s likely that other long-dead bodies may have been preserved in the same way, he said.

Archaeologist Andreas Putzer of the South Tyrol Museum of Archaeology in Bolzano in Italy, where Ötzi’s body and artifacts are on display, said that closer investigation of the mummy could confirm if it had indeed been exposed to glacial meltwater over time. 

"A mummy submerged in water would lose its epidermis [skin], hair, and nails," Putzer, who was not involved in the new research, told Live Science in an email. "Normally this happens to bodies of drowned persons." Pathological research could determine if the remains were ever submerged in melted ice water, as the new study proposes, or if they were continually frozen in ice, he said.

A third of the world's glaciers in culturally and naturally significant World Heritage sites will almost completely disappear by 2050, a United Nations climate report warns. Without further reductions in greenhouse gas emissions, half of World Heritage glaciers could almost completely vanish after another 50 years. 

But if humanity limits the global temperature increase to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels, two-thirds of World Heritage glaciers could survive, the report said. That 1.5 C increase matches a goal of the Paris Agreement, which countries agreed to in 2015 at the U.N. Framework Convention on Climate Change.

"The changes are rapid and really alarming," Daniel Farinotti, a co-author of the new report and a professor of glaciology at ETH Zurich in Switzerland, told Live Science. "If we want to do something about it, we need to reduce global emissions of greenhouse gases, and we need to do that now."

Glaciers projected to disappear by 2050 include those in Yellowstone and Yosemite national parks, and many of the imperiled glaciers provide local communities and ecosystems with vital water resources, according to the report, published this month by the U.N. Educational, Scientific and Cultural Organization (UNESCO). World Heritage sites are legally protected locations with "cultural and natural heritage around the world considered to be of outstanding value to humanity," and UNESCO administers their protections, according to the organization's website.

Related: Study of nearly every glacier on Earth shows ice loss is speeding up

The projected loss of one-third of World Heritage glaciers will happen regardless of future climate mitigation efforts — the damage is already baked in, Tales Carvalho Resende, co-author of the report and a UNESCO project officer, told Live Science. "Even if we drastically reduce carbon emissions today, these glaciers have an inertia, so they will keep retreating," he said. The so-called "business as usual scenario," with no further reductions in greenhouse gas emissions, sees 50% of World Heritage glaciers lost by 2100.

Recent data show the world falling short of its Paris Agreement goals, The New York Times reported. However, UNESCO hopes its report helps spur a recommitment to those efforts. "We believe this can be a strong message to decision-makers, given that these places are iconic for humanity," Carvalho Resende said.

In addition to stressing the urgent need for reduced emissions, UNESCO recommended several adaptive steps. These include improving the monitoring of glaciers; developing early warning systems for floods and other disasters associated with glacial retreat; and working with Indigenous peoples, whose knowledge on managing resources is "embedded in culture, traditional practices and belief systems."

Vital water resources and cultural icons

Losses predicted by 2050 include "the last remaining glaciers in Africa (on Mount Kilimanjaro, Mount Kenya and the Rwenzori-Virunga mountains), as well as other iconic sites in Europe and North America," such as Italy's Dolomites and U.S. national parks, according to the report. The "business-as-usual" scenario would imperil larger glaciers, such as those at Machu Picchu in Peru and Olympic National Park in Washington state. 

UNESCO's publication draws from two decades of satellite data on ice loss, as well as models estimating ice thickness, Farinotti said. The nearly 19,000 glaciers at 50 World Heritage sites represent almost 10% of the planet's glacier area, and their retreat has accelerated since 2000. Overall, World Heritage glaciers lost nearly 1,300 billion tons (1,200 billion metric tons) of ice from 2000 to 2020, or an average yearly "amount equivalent to the total annual volume of water consumed in France and Spain together," the report said.

Losing these ice giants will come with enormous costs. They provide habitats for biodiversity, reflective surfaces that help limit warming, and fresh water for drinking and agriculture to half of humanity. Though in the short term, higher global temperatures may increase water flow from melting glaciers, "once a maximum meltwater contribution (peak water) is reached, annual runoff is then reduced as the glacier shrinks" so that it can no longer produce much meltwater, the report said.

This could prove devastating in populous areas, particularly in countries such as India and China, which lie downstream of the Himalayas, Farinotti said. "They get water directly from those mountains," he said. And during "drought, in some areas, either you get water from the glaciers, or you don't get water at all."

Stunned scientists have uncovered more than 900 never-before-seen species of microbes living inside glaciers on the Tibetan Plateau. Analysis of the microbes' genomes revealed that some have the potential to spawn new pandemics, if rapid melting caused by climate change releases them from their icy prisons. 

In a new study, researchers from the Chinese Academy of Sciences took ice samples from 21 glaciers on the Tibetan Plateau — a high-altitude region in Asia wedged between the Himalayan mountain range to the south and the Taklamakan Desert to the north. The team then sequenced the DNA of the microscopic organisms locked inside the ice, creating a massive database of microbe genomes that they named the Tibetan Glacier Genome and Gene (TG2G) catalog. It is the first time that a microbial community hidden within a glacier has been genetically sequenced.   

The team found 968 microbial species frozen within the ice — mostly bacteria but also algae, archaea and fungi, the researchers reported June 27 in the journal Nature Biotechnology. But perhaps more surprisingly, around 98% of those species were completely new to science. This level of microbial diversity was unexpected because of the challenges associated with living inside glaciers, the researchers said. "Despite extreme environmental conditions, such as low temperatures, high levels of solar radiation, periodic freeze-thaw cycles and nutrient limitation, the surfaces of glaciers support a diverse array of life," the study authors wrote.

The researchers aren't sure exactly how old some of these microbes are; prior studies have shown that it is possible to revive microbes that have been trapped in ice for up to 10,000 years, according to the study. 

Related: Discovery of 'hidden world' under Antarctic ice has scientists 'jumping for joy' 

This is not the first time that scientists have found a surprising abundance of microbes living in Tibetan glaciers. In January 2020, a team that analyzed ice cores from a single glacier uncovered 33 different groups of viruses living within the ice, 28 of which had never been seen before.

The surprising microbial diversity within glaciers, coupled with an increase in melting glacial ice due to climate change, boosts the chances that potentially dangerous microbes — most likely bacteria — will escape and wreak havoc, researchers said. "Ice-entrapped pathogenic microbes could lead to local epidemics and even pandemics" if they are released into the environment, the authors wrote. 

Evidence suggests that some of the newfound bacteria could be very dangerous to humans and other organisms. The team identified 27,000 potential virulence factors — molecules that help bacteria invade and colonize potential hosts —  within the TG2G catalog. The researchers warned that around 47% of these virulence factors have never been seen before, and so there is no way of knowing how harmful the bacteria could be.

Even if these potentially pathogenic bacteria do not survive for long after escaping their glaciers, they can still cause problems, the researchers said. Bacteria have the unique ability to exchange large sections of their DNA, known as mobile genetic elements (MGEs), with other bacteria. So even if the glacial bacteria die shortly after being thawed out, they can still pass on some of their virulence to other bacteria they encounter. This genetic interaction between glacier microbes and modern microorganisms "could be particularly dangerous," the scientists wrote.

The Tibetan Plateau glaciers could be a hot spot for unleashing future pandemics because they feed fresh water into a number of waterways, including the Yangtze River, the Yellow River and the Ganges River, which supply two of the most populated countries in the world: China and India. Pandemics spread quickly through highly populated areas, as the world witnessed during the COVID-19 pandemic.

But this potential problem won't just affect Asia. There are more than 20,000 glaciers on Earth covering around 10% of the planet's land mass, and each glacier is likely to have its own unique microbial communities. In April 2021, a study using satellite images of glaciers found that nearly every glacier on Earth showed an accelerated rate of ice loss between 2000 and 2019, which increases the risk that pandemic-spawning microbes could escape anywhere on the planet. The researchers warned that the "potential health risks [of these microbes] need to be evaluated" before they are released from their icy prisons. 

However, there is a silver lining to this new study. Genetic records of microbial communities, such as the TG2G catalog, could be used as "toolkits" for bioprospecting — exploring natural systems to find valuable new compounds that can be used in medicine, cosmetics and other beneficial technologies. That makes databases like TG2G very important, especially if the newly discovered species go extinct in the future; an outcome that is all too likely if they cannot adapt to the changes in their frozen habitat, the researchers wrote.

Originally published on Live Science.

Glacial archaeologists in Norway have discovered weapons and secret hideaways on a remote mountain where stealthy hunters waited for reindeer more than a millennium ago.

While surveying part of the inland mountain peak Sandgrovskaret, the archaeological team recovered five arrows, three of which are up to 1,700 years old. The researchers also discovered 40 stone-built hunting blinds, which made the hunters "invisible" to nearby reindeer. 

"When the reindeer had approached to within 10-20 meters [33 to 66 feet], the hunter would get up and start shooting arrows," said Lars Pilø, an archaeologist at the Department of Cultural Heritage, Innlandet County Council, Norway, co-director of the Glacier Archaeology Program and the editor of the Secrets of the Ice website.

For years, Pilø and his colleagues have trekked into the mountains to search for artifacts exposed by melting glaciers. They found this particular site in 2013, but they weren't able to return to do a large systematic survey there until 2018, when they found the weapons and hunting blinds. "There is a lot of melting going on due to climate change, and we had to prioritize other sites in the short time window for glacial archaeological fieldwork," he said.

Related: Photos: Ancient arrows from reindeer hunters found in Norway 

Of the five arrows, three still have a preserved iron arrowhead. Based on an analysis of the arrowheads' shapes, these weapons likely date to between A.D. 300 and 600, Pilø said.

One of the three iron arrowheads is "a rare type not found at the ice before and hardly in graves in the lowlands, either," Pilø told Live Science in an email. When Secrets of the Ice announced the findings on social media in February, they received "quite a lot of comments that it had to be a spearhead, but the arrow shaft was found beside it, so it is an arrow," he noted.

The other two arrows — those without iron arrowheads — likely date to the first millennium B.C., Pilø said.

The reindeer hunters who wielded the weapons likely hid in the nearby blinds. "The reindeer are very wary of movement, so the hunters had to make themselves invisible to get within shooting distance," Secrets of the Ice wrote in a Feb. 19 Facebook post.

The arrows couldn't have flown more than 66 feet (20 m), "so the hunters needed a good place to hide. And if there wasn't one, they built one themselves," Secrets of the Ice wrote. 

The hunters didn't live on the 6,234-foot-tall (1,900 m) mountain. "Most likely they lived down in the valleys, but clearly had large hunting stations higher up in the mountains," Espen Finstad, a glacial archaeologist, told sciencenorway.no. During the Stone Age, people in this area lived in simple settlements. Later, during the Iron Age, they lived in "grand longhouses down in the valley," Finstad said. In 2021, glacial archaeologists announced the discovery of some of these longhouses, Live Science previously reported. 

The team also found 77 pieces of reindeer antler and bone and 32 scaring sticks, which would have been placed in the ground like fence posts to guide spooked reindeer toward the ready archers, Pilø said. The scaring sticks date to between A.D. 200 and 1000, during the Iron Age, he added. 

"Scaring sticks were used to lead the reindeer toward the hunting blinds, though exactly how this happened is still something that we are trying to understand," Pilø told Live Science.

Pilø and his colleagues plan to continue surveys in nearby mountains with melting ice. After all, time is running out; a new study finds that total glacier area in Norway has shrunk by 14% compared with the last time glaciers were measured from 1999 to 2006, according to a translated statement released in February by the Norwegian Water Resources and Energy Directorate (NVE). 

Originally published on Live Science.

The "Blue Blob," an unusually cold patch of water in the Arctic, has halved the rate at which Iceland's glaciers are melting, but a new study reveals that the effects of climate change will catch up to the massive ice chunks if temperatures are not kept in check.    

The Blue Blob is an undefined area of the North Atlantic Ocean located south of Iceland and Greenland. At its peak coldness, in 2015, the Blue Blob was 2.5 degrees Fahrenheit (1.4 degrees Celsius) colder than the surrounding waters. Before the emergence of the Blue Blob, Iceland's glaciers were losing a staggering 11 gigatons of ice every year due to melting. But since the cool patch emerged in 2011, that rate has more than halved to a slightly less worrying 5 gigatons a year ​​— even though the rest of the Arctic is warming four times faster than anywhere else on Earth, according to a statement from the American Geophysical Union.      

In the new study, published online Jan. 24 in the journal Geophysical Research Letters, researchers used climate models to predict how long the Blue Blob could continue to slow the glaciers' rampant melting. They found that the rising temperatures will overcome the cooling effect and match rapid melting rates seen in nearby Greenland and the Norwegian archipelago Svalbard by the mid-2050s. 

Related: 10 things you need to know about Arctic sea ice

Researchers say this finding is important because it improves our understanding of trends throughout the Arctic. "It's crucial to have an idea of the possible feedbacks in the Arctic, because it's a region that is changing so fast," lead author Brice Noël, a climate scientist at Utrecht University in the Netherlands, said in the statement. "It's important to know what we can expect in a future warmer climate."

Iceland currently hosts four major ice caps each larger than 193 square miles (500 square kilometers), seven smaller ice masses each larger than 4 square miles (10 square km) and around 250 other glaciers smaller than 4 square miles. In total, the volume of ice on the island nation is estimated to be around 816 cubic miles (3,400 cubic km), which would be enough to raise global sea levels by 0.35 inches (9 millimeters) if it completely melted, the researchers wrote in the paper. This is the equivalent to around three times the current global sea rise we are experiencing every year, according to the Smithsonian Institute.

Almost all of Iceland's glaciers terminate on land, meaning they do not come into contact with the sea. Therefore, the rate at which they melt is dependent on their surface mass balance, which is the difference between ice gained from winter snowfall and ice lost from meltwater runoff in the summer. However, the Blue Blob is so cold that it decreases the temperature of the air that flows over it, which then cools the atmosphere surrounding Iceland and, in turn, reduces the surface mass balance of its ice masses, meaning less ice is lost.

Using the latest climate prediction models and local atmospheric temperature readings dating back to the 1990s, the team pinpointed when rising temperatures caused by climate change would outweigh the influence of the Blue Blob on Iceland's surface mass balance. The researchers estimated that by 2100, a third of Iceland's glaciers may be gone and that by 2300, there likely will be no glaciers left in the country. 

The researchers' approach could be used to better understand the melting rates of glaciers in other places, such as the Himalayas and Patagonia, Fiamma Straneo, an oceanographer at the Scripps Institution of Oceanography in California who was not involved in the study, said in the statement.

Scientists are still unsure why the Blue Blob is so much colder than the surrounding waters. Some researchers think it is part of natural variability in sea-surface temperatures in the Arctic that has increased the amount of upwelling of cold water from the deep sea. Others think climate change has disrupted surface currents that push warmer water into the Arctic from tropical regions in the Atlantic. 

Regardless of how the Blue Blob came to be, its cooling effect on Iceland will not last forever, and if left unchecked, climate change will cause the total disappearance of Iceland's glaciers in the not-too-distant future. 

"In the end, the message is still clear," Noël said in the statement. "The Arctic is warming fast. If we wish to see glaciers in Iceland, then we have to curb the warming."

Originally published on Live Science.

The melting of Earth's polar ice is warping the planet's crust. 

This shape change is subtle, but it occurs many hundreds of miles away from the ice sheets. Researchers may be able to monitor the shift as part of research to understand how climate change will affect sea level; understanding the warping is also important, because scientists need to be able to correct for this ground motion when measuring other types of geological processes, the study authors wrote in the August issue of the journal Geophysical Research Letters.

Scientists already knew that when ice disappears, the crust underneath changes. Imagine lifting your head from a memory foam pillow: As the weight of your head is lifted, the pillow gradually fluffs back up, still moving after you've vacated the bed. Something similar happens when a glacier retreats. The crust beneath, no longer under all that weight, slowly pops back up. This is called isostatic rebound, and it's very slow indeed. In some high-latitude regions, the ground is still rebounding from the retreat of the ice sheets during the end of the last ice age. 

Related: Antarctica: The ice-covered bottom of the world (Photos)

But now, the polar regions are losing ice at an increasing rate due to climate change. From 2000 to 2010, ice loss from Antarctica, Greenland and mountain glaciers increased 60% compared with the ice loss between 1990 and 2000, according to a paper published in 2020 in The Cryosphere. This melt is affecting the shape of the crust, just as the loss of ice at the close of the Ice Age did. But most research has focused on the crust changes right under and around the ice sheets. Even when researchers do study farther-off effects, they focus on vertical changes in the crust shape. But the crustal motion after ice loss is three-dimensional, meaning it shifts horizontally, too. 

Sophie Coulson, a postdoctoral researcher at Los Alamos National Laboratory in New Mexico who conducted the research while at Harvard University, wanted to take a global, 3D look at the impact of the ice loss of the 21st century. She and her colleagues used satellite data collected between 2003 and 2018 to look for tiny movements in the crust, comparing those changes with ice loss in Antarctica, Greenland and high-latitude glaciers year to year. 

They found that in many cases, the horizontal movement of the crust outpaced the vertical movement (uplift). The movement was very dependent on how much ice was lost each year, but in both high and low-loss years, most of North America averaged more horizontal than vertical motion. The horizontal creep, mostly northward, peaked in 2012 at up to 0.017 inches (0.45 millimeters). In low-loss years, this movement averaged around 0.004 inches (0.1 mm) for the whole continent. 

In the early 2000s, ice retreated rapidly from the Antarctic peninsula and from West Antarctica, but East Antarctica gained ice. This gain and loss ended up averaging out in terms of Earth's crust, so most of the deformation was limited to a relatively small area in the southern Pacific. The Northern Hemisphere was a different story. Ice loss from the northern latitudes was linked to an average of 0.015 inches (0.4 mm) of horizontal - mostly northward - motion each year in the Northern Hemisphere. This included up to 0.01 inches (0.3 mm) of movement in Canada and the United States, and up to 0.008 inches (0.2 mm) in Europe and Scandinavia. 

Those numbers may seem insignificant, but they add up over time. And this warping may affect how future ice loss plays out. 

"In some parts of Antarctica, for example, the rebounding of the crust is changing the slope of the bedrock under the ice sheet, and that can affect the ice dynamics," Coulson told the Harvard Gazette. A steeper slope means a faster flow of ice toward the sea.

Originally published on Live Science.

Like a bowl of spaghetti noodles spilled across the floor of the North Sea, a vast array of hidden tunnel valleys wind and meander across what was once an ice-covered landscape. 

These valleys are remnants of ancient rivers that once drained water from melting ice sheets.

Now, scientists have achieved the clearest view yet of these channels. They're buried hundreds of feet beneath the seafloor, and they are enormous, ranging from about 0.6 to 3.7 miles (1 to 6 kilometers) wide.

The new imaging reveals fine-grained details within these expansive features: small, delicate ridges of sediment, larger walls of sediment that can be miles long and craters called kettle holes left behind by melting chunks of ice.

Related: See photos of Earth's vanishing ice

"We didn't expect to find these kinds of footprints of the ice sheet within the channels themselves," said study lead author James Kirkham, a marine geophysicist at the British Antarctic Survey and the University of Cambridge. "And that tells us, actually, that the ice was interacting with the channels a lot more than previously assumed."

Footprints of glaciers

These channels are the footprints of glaciers left behind from between 700,000 and 100,000 years ago, when most of the North Sea, as well as the northern two-thirds of the United Kingdom and all of Ireland were often buried under huge ice sheets. (The ice advanced and retreated seven or eight times within this period, Kirkham told Live Science.)

During periods when the climate warmed and the ice retreated, these ice sheets discharged water through hidden glacial channels beneath the ice. These channels left their imprint on the sediments below. More sediments then piled on top as the ice vanished, entombing the imprints deep beneath the seafloor.

To see these ancient impressions, geophysicists use a technology called 3D seismic reflection. In this process, scientists shoot bursts of compressed air toward the seafloor. The resulting sound waves travel through the rock and sediment layers beneath the seafloor and bounce back, where they're picked up by a shipboard receiver. Because sound travels at different speeds through different types of rock and sediment, the data can be reconstructed into a picture of the subsurface.

A map of the undersea tunnel valleys looks like a vast array of squiggles, like a scattering of spilled noodles. But zoomed in, the channels are visible in stunning detail. They meander and wind like rivers (which they once were), bounded by shear cliffs and rugged slopes. Some plummet 310 miles (500 km) deep into the sediment and are dozens of miles long.

Water and ice

The landforms within the tunnel valleys paint a complicated picture of ice retreat, Kirkham said. At times, there are signs of fairly slow and steady retreat. For example, eskers are ridges of sediment around 16 feet (5 meters) high that can stretch for many miles. They're also seen in modern-day glaciers that are moving gradually.

Related: Photos: Ancient human remains found beneath the North Sea

In other spots, the channels are punctuated by small, delicate ridges that indicate fast, dynamic ice flow, Kirkham said. Another sign of fast-moving surges of ice and water are kettle holes, which are spots where a large iceberg that has detached from the main ice sheet and moved to a new location finally gets stuck and melts.

The channels seem to have been carved by both water and ice. In some spots, there are braided channels meandering through the bottom of the canyons, Kirkham said. These were formed by flowing water, which seems to have eroded the sediment beneath the ice sheet. Once that void formed, however, the underside of the ice sagged into that gap, carving out a broader path. There are also places where valley walls seem to have collapsed, probably after the ice that was filling the valley melted away, enabling the sediment to slump in its stead.

These undersea tunnel valleys are an interesting snapshot of the past, but their real value may be in helping to predict the future. As the climate warms, the ice caps are again on the retreat. If the climate gets hot enough, West Antarctica might someday look a lot like the North Sea did 100,000 years ago, Kirkham said. The Greenland ice sheet, too, is melting rapidly. Studying the remnants of the North Sea channels and how they formed could reveal more about the dynamics governing the loss of today's ice sheets. In particular, the geological record could hint at how small-scale factors like moving water affect how much ice ends up melting into the sea, and how quickly, which could lead to better models of sea-level rise.

"In the future, we'd like to explore that idea a bit further by continued mapping, and also some computer modeling to work out how we've produced these landforms and what would need to happen at the base of an ice sheet to generate them," Kirkham said.

The findings appear today (Sept. 8) in the journal Geology. 

Originally published on Live Science

The glacial slopes of Mount Rainier might seem lifeless at first glance. That is, until the ice worms emerge.

As if on cue, billions of black, threadlike worms wriggle their way to the surface of the snow every summer, when the sun directly strikes the glaciers. And scientists still don't know why.

If they want the answer to that question or any other related to this mysterious creature, scientists have to act fast. Black ice worms (Mesenchytraeus solifugus) are the only worm species known to science that spend their entire lives in ice. As glaciers in the region shrink due to global warming, these worms risk becoming extinct alongside them.

Related: Study of nearly every glacier on Earth shows ice loss is speeding up

To beat the ticking clock, Scott Hotaling, a biologist at Washington State University, makes sure that as soon as ice worms appear on the mountain's Paradise Glacier, so does he. Hotaling is one of the few people who actively studies this species.

"I saw my first ice worms when I was working [a summer job] in Olympic National Park," in Washington State, Hotaling told Live Science. He had been a student of ecology at the time, but the ice worms made him realize that he could carve a unique niche for himself as a scientist. "It was cool because I would ask these questions — like, 'Where do they live?' and 'How do they reproduce?' — and I realized that actual scientists were still asking those same questions," said Hotaling. 

The worms were first described in 1898, but few people studied them in the intervening century. As a result, not much is known about them despite the fact that they seem to be the most abundant species living inside glaciers.

For instance, we don't know why they emerge in the summer, or why they spend most of their lives buried deep in ice. Further, what they do underneath the ice for so long is a complete mystery. 

However, what little we do know about them suggests these worms are amazing.

For example, they live for months in ice, but they cannot tolerate freezing. "It's wild, but they basically survive at the very edge of their tolerance," said Hotaling. These are worms that spend most of the year buried under ice, only to emerge briefly in the summer. Paradoxically, being exposed to wind on the surface puts them most at risk of freezing solid. They keep warm enough to survive by being buried in ice. "Think of it like living in an igloo," he said. "It's negative 40 degrees [Celsius, or minus 40 degrees Fahrenheit] outside, but it's probably zero degrees Celsius [32 F] on the inside." 

Hotaling thinks the worms' summer behavior resembles that of their distant cousins, earthworms. They crawl through the ice, eating the bacteria and algae in front of them and excreting waste behind. But what they do all winter is "the ultimate ice worm mystery," he said. He would love to know the answer, but these elusive worms are buried beneath dozens of feet of snow for much of their lives, making them hard to study.

Despite being widespread throughout Alaska and the Pacific Northwest, these worms are limited to very specific glacial habitats where they can exist on the fringes between alpine forests and frozen mountain peaks. But it likely wasn't always that way. "Our limited genetic evidence suggests that ice worms probably covered the landscape during the last glacial period," Hotaling said. When the glaciers retreated at the end of the Pleistocene, around 20,000 years ago, the worms were left on isolated peaks, where they have thrived ever since.

They are not alone up there, either. Hotaling noted that ice worms are likely an important food source for bird species that brave the cold. Among these are gray-crowned rosy finches, the highest-elevation nesting bird species in North America. Gray-crowned rosy finches build nests directly on the ice and forage in the snow for the hidden bounty of ice worms, suggesting the worms are a crucial food supply for the finches.

Even though not much is known about ice worms, it's clear that they are a key part of an imperiled ecosystem. As glaciers recede, they risk taking the worms and everything that relies on those worms with them, and Hotaling is acutely aware that his research is time-sensitive. "These are some of the most rapidly changing habitats on Earth, yet we know so little about them," said Hotaling.

Originally published on Live Science.

Atop the French Alps, thousands of feet above sea level, the normally white snow sometimes appears stained with blotches of what appears to be dark red blood, some of which extend for miles. 

But no, these aren't the sites of violent mountaintop massacres — the spooky red stains, known as "glacier blood," actually come from microalgae that live in the snow, and scientists recently trekked into the Alps to study these mysterious organisms.

The expedition is part of the AlpAlga project, an effort to study microalgae living in the mountains, 3,280 to 9,842 feet (1,000 to 3,000 meters) above sea level. Much like the microalgae that inhabit oceans, lakes and rivers, snow-borne microalgae help form the base of the food web of a mountainous ecosystem and likely react to pollution and climate change in a similar fashion, said Eric Maréchal, a coordinator of the AlpAlga consortium and a director of the Laboratory of Cellular and Plant Physiology, a research facility in Grenoble, France.

Related: Snowball Earth: When the Blue Planet went white

"The public is well instructed about the presence of algae in the oceans," but less aware of related microorganisms living in the soil atop mountains and in the snow that accumulates at those high altitudes, Maréchal said. When the team clambers up mountains in the French Alps, they're hiking through an environment that's teeming with microscopic life, "just like in the ocean, but it's in the snow. It's in the interstitial water between tiny crystals of ice." 

In general, microalgae cells measure only a few ten-thousandths of an inch (thousandths of a millimeter) across, and they can exist as either isolated single-cell organisms or colonies. They produce sugars through photosynthesis, "and all the ecosystem eats that, directly and indirectly," whether the algae grows in the liquid ocean or in compacted snow in the mountains, Maréchal said. 

The algae that turn snow red are technically green algae, as they belong to the phylum Chlorophyta and contain a specific form of chlorophyll, the green pigment that enables photosynthesis. However, in addition to chlorophyll, these algae also contain carotenoids, the same orange and red pigments that appear in vegetables like carrots. Carotenoids act as antioxidants and likely shield the algae from the damaging effects of intense light and ultraviolet radiation found at high elevations, Maréchal said. 

During an algal bloom, when a large quantity of algae grows very rapidly, the surrounding snow can appear red or orange due to the related accumulation of carotenoids — hence the gruesome-looking glacier blood. 

Maréchal last saw glacier blood before the COVID-19 pandemic, in spring 2019, and he recalls walking over miles and miles of red snow. "Everywhere I put my eyes, it was red," he said. "We walked all day, seeing surfaces stained in red … It was really impressive." But despite glacial blood being a well-known phenomenon, scientists know very little about the algae's biology, or how climate change might impact this core feature of mountain ecosystems. 

Just as nutrient-rich pollution fuels algal blooms in the ocean, nutrients delivered to the mountaintop in precipitation and wind could theoretically fuel algal blooms in the Alps, Maréchal said. And rising levels of carbon dioxide in the atmosphere could theoretically also spur the algae's growth, he said. While that's fine for the algae, these changes could trigger a harmful snowball effect in the surrounding ecosystem.

Related: Photographic proof of climate change: Time-lapse images of retreating glaciers

For example, studies suggest that the reddish snow reflects light less effectively than untarnished white snow and therefore melts faster, according to a 2016 report published in the journal Nature. And it's unclear whether, as with ocean-borne algal blooms, climate change and pollution will cause red snow to appear more frequently, potentially to the detriment of other organisms in the environment, Maréchal said. 

At this point, "what we think is that the algae are probably markers of climate change," in that the organisms' growth reflects the rising carbon dioxide levels and related changes in the environment, Maréchal said. Although this makes sense anecdotally, there's not yet enough data to actually track how the algae change through time. "People who are familiar with the mountains, they say, 'Oh, we see more and more red snows.' But we don't actually measure [it]," he said. So Maréchal and his team set out to fill those gaps in the literature.

In their most recent study, published Monday (June 7) in the journal Frontiers in Plant Science, the team studied the prevalence of microalgae species at five different sites in the French Alps, covering elevations between 4,000 and 9,645 feet (1,250 to 2,940 m) above sea level. They collected soil samples from the sites in late summer 2016, after the seasonal snows had melted away for the year. Several members of the team specialized in extracting DNA from the environment, which allowed the group to discover genetic material left from dead, broken algal cells that previously lived in each area.

"Those people are like the scientific police; they can track the presence of organisms with the DNA that the organism leaves behind," Maréchal said. The team pulled out all of the algal DNA from their samples, revealing which algal species grew where, elevation-wise; the survey also hinted at the environmental conditions each species preferred.

For example, algae of the genus Sanguina, known for causing red snow, appeared only at elevations 6,560 feet (2,000 m) above sea level and higher; meanwhile, algae in the genuses Desmococcus and Symbiochloris cropped up only at low altitudes, below 4,920 feet (1,500 m). "We were maybe expecting something, but not such a spectacular zonation of the species," with many species exclusively confined to either high or low elevations, Maréchal said. 

This study serves as a starting point for the AlpAlga project as the team attempts to address the many remaining questions about glacier blood. We still don't know what environmental conditions trigger the algal blooms; how the seasonal appearance and disappearance of snow affects the algal life cycle; or how the blooms affect snowmelt and glacial retreat, on a large scale, Maréchal noted. 

In an upcoming expedition later this month, the team plans to establish a long-term research site where they can track algal blooms through the changing seasons. They will analyze the gradients between white and red snow, to see what conditions cause blooms to occur, and sample algal cells to cultivate in their labs. These lines of research should not only unpack the mysteries of glacier blood, but also grant insight into how the Alps ecosystem might change as the climate warms, Maréchal said.

Melting glaciers in the polar regions often make headlines, partially because their impact on sea-level rise has been widely discussed, Maréchal said. But climate change also has a huge impact on landlocked glaciers in mountainous regions, where glacial water serves as a reservoir for river systems, he said. So in the long run, the impacts of climate change will be felt in mountainous regions, "even if you're far from the seashore." 

Originally published on Live Science.

Earth's glaciers are shrinking, and in the past 20 years, the rate of shrinkage has steadily sped up, according to a new study of nearly every glacier on the planet.

Glaciers mostly lose mass through ice melt, but they also shrink due to other processes, such as sublimation, where water evaporates directly from the ice, and calving, where large chunks of ice break off the edge of a glacier, according to the National Oceanic and Atmospheric Administration (NOAA). By tracking how quickly glaciers are shrinking, scientists can better predict how quickly sea levels may rise, particularly as climate change drives up average global temperatures. 

But estimating the rate of glacier shrinkage can be notoriously difficult; past estimates relied on field studies of only a few hundred glaciers out of the more than 200,000 on Earth, as well as sparse satellite data with limited resolution, the authors noted in their new study, published Wednesday (April 28) in the journal Nature.

Some of this satellite data captured changes in surface elevation, but only sampled a few places and at sparse time points. Other satellites detected slight shifts in the Earth's gravitational field, but could not disentangle how much glacier shrinkage contributed to these shifts, as opposed to mass changes in ice sheets or solid earth, for instance.

Related: Time-lapse images of retreating glaciers 

To zero in on a more precise estimate, the team used myriad satellite and aerial images to survey 217,175 glaciers, accounting for nearly all of Earth's glaciers. In particular, a 20-year archive of images from NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a high-resolution sensor aboard the Terra satellite, supplied the team with a wealth of data and allowed them to make more certain estimates of glacier mass loss through time.

"We not only have the complete spatial coverage of all glaciers, but also repeat temporal sampling," meaning measurements taken from many points in time, said first author Romain Hugonnet, a doctoral student at the University of Toulouse in France and the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zürich in Switzerland. 

The team found that, between 2000 and 2019, glaciers collectively lost an average of 293.7 billion tons (267 billion metric tonnes) of mass per year, give or take 17.6 billion tons (16 billion metric tonnes); this accounts for about 21% of the observed sea-level rise in that time frame, the authors noted. 

And for each decade since 2000, the overall rate of glacier mass loss has been accelerating, increasing by about 52.8 billion tons (48 billion metric tonnes) per year, which may account for an observed acceleration in sea-level rise.

These estimates significantly narrow the uncertainty around how much mass glaciers lost in recent decades, Hugonnet said. For instance, the latest report from the Intergovernmental Panel on Climate Change (IPCC) and a recent global study, published in 2019 in the journal Nature, both calculated mass loss estimates in the same ballpark as the new study; but their margins of error spanned several hundred gigatonnes on either side.

Hugonnet and his team were able to greatly reduce this uncertainty by using the ASTER data.

ASTER captures images on the visible and near-infrared spectrum, "so almost what we see with our own eyes," Hugonnet said. Because the sensor orbits Earth about 438 miles (750 kilometers) above the planet's surface, it can snap images of the same locations from multiple angles: once as it passes directly over a spot and once as if it's "looking back" from where it came. 

The two snapshots can then be used to reconstruct the 3D topography of Earth's surface, and in this case, the 3D structure of glaciers across the planet. Hugonnet and his team quantified these changes in volume and then multiplied that by the density of glacier ice, to determine how much mass the glaciers had lost.

The group also double-checked their work against data from NASA's Ice, Cloud, and land Elevation Satellite (ICESat) and Operation IceBridge campaigns, a NASA project in which a fleet of research aircraft surveys Earth's polar ice. This additional data confirmed that the ASTER images generally matched up with other available data front the same time period, and it also helped the team correct for statistical "noise" in the ASTER data.

Using these methods, the team calculated a fairly confident estimate, but some uncertainty still remains, Hugonnet said. 

"The problem with glaciers is that we're not only losing ice, we're also losing firn," a kind of partially compacted snow usually found on top of glaciers, he said. The current study didn't differentiate firn from ice when estimating mass loss, "so it's, right now, our largest source of uncertainty," in terms of nailing down a precise rate, Hugonnet said. 

In addition, the team noted that not all Earth's glaciers lost mass at the same rates. "What was even more interesting, and a bit surprising, was to see that some regions decelerated and others accelerated," Hugonnet said. 

For instance, mass loss from glaciers in Alaska and western Canada ramped up significantly in the study time frame, while loss from Icelandic, Scandinavian and southeast Greenland glaciers slowed between the early 2000s and late 2010s. Zooming in on these regions, the authors found that regional climate conditions, specifically long-term fluctuations in precipitation and temperature, helped explain these stark differences.

So while Iceland, Scandinavia and Greenland entered a decade of relatively cool, wet conditions in the second decade of the 21st century, northwestern North America entered a relatively dry period, meaning glaciers ultimately lost more ice than they gained snow. "We have those fluctuations that exist in some regions and can last for about a decade, sometimes," Hugonnet said.

"This is also why we need such globally complete sets of observations, such as the one we provided," he noted. 

Tracking average glacier mass loss, on a global scale, can help scientists predict global sea-level rise; but on a local scale, glacier mass loss can drastically alter nearby bodies of water and the availability of water resources, as well as threaten to trigger disasters, such as avalanches and devastating spring floods, Hugonnet said. So it's important to capture both the big picture and fine details.

Originally published on Live Science.

Rapid melt is reshaping coastal Greenland, potentially altering the human and animal ecosystems along the country's coast. 

New research published in the Journal of Geophysical Research: Earth Surface on Oct. 27 finds that the ice retreat in Greenland has changed the way glaciers flow and where they dump into the sea. These changes could impact ice loss from Greenland in the future, the researchers wrote. 

Recent studies have shown that Greenland is losing 500 gigatons of ice each year, more than can be replenished by new snowfall. Annual ice loss is 14% greater today than it was between 1985 and 1999. And the meltwater from this ice loss is lubricating the ice sheet so that it slides more easily on its underlying bedrock, hastening the continued melt.

Related: Photos of Greenland's gorgeous glaciers

The new study, led by National Snow and Ice Data Center research scientist Twila Moon, breaks down the changes in more detail. Moon and her colleagues combined two types of data from satellite imagery: how fast the ice sheet is moving and where glaciers terminate on their path downhill. When a glacier retreats, its terminus doesn't reach as far downvalley as it once did.

They found, first, that glacier retreat is now the norm in Greenland. Eighty-nine percent of glaciers had retreated substantially within the last decade, the researchers wrote in their paper. Virtually none had advanced. 

However, this reshaping of glaciers translated into a variety of changes in glacier movement. Some glaciers were speeding up, flowing more rapidly toward the sea, the researchers found; others were flowing more slowly. And over several years to a decade, a single glacier could do both, depending on the topography around it. Glaciers are rivers of ice, so their flow is partially determined not just by how quickly they're melting, but by what's underneath them.

For example, the Kjer and Hayes glaciers in northwestern Greenland sped up at their primary outlets to the sea from the 1990s to 2010, but other ice outlets to the ocean nearby slowed down. In one case, the southerly portion of one of those outlets sped up, then slowed again. The researchers saw evidence of ice channels narrowing, of re-routing meltwater paths, and even of the slowing of new ice so that glaciers are stranded in place, more like lakes than rivers.

All of this local variation may be very important for predicting how quickly Greenland's ice will disappear in the future. The changes will also likely affect how and where nutrients enter the water, where there are open fjords versus ice, and where freshwater is available. 

"As the Arctic ocean and atmosphere warm, we can clearly see the flow of ice into the ocean accelerate and the ice edge retreat," study co-author Alex Gardner, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. "When we look more closely, however, we can see the complexity of how individual glaciers respond, owing to differences in the properties of the ocean water that reach the glacier front, the bedrock and till that lie below, and in how meltwater runoff is routed beneath. Understanding the complexity of individual glacier response is critical to improving projections of ice sheet change and the associated sea level rise that will arrive at our shores."

Originally published on Live Science.

A giant, catastrophic tsunami in Alaska triggered by a landslide of rock left unstable after glacier melting is likely to occur in the next two decades, scientists fear - and it could happen within the next 12 months.

A group of scientists warned of the prospects of this impending disaster in Prince William Sound in an open letter to the Alaska Department of Natural Resources (ADNR) in May.

While the potential risks of such a landslide are very serious, there remain a lot of unknowns about just how or when this calamity could take place.

What is clear is that glacier retreat in Prince William Sound, along the south coast of Alaska, does seem to be having an impact on mountain slopes above Barry Arm, about 97 kilometers (60 miles) east of Anchorage.

Analysis of satellite imagery suggests that as Barry Glacier retreats from Barry Arm due to ongoing melting, a large rocky scar called a scarp is emerging on the face of the mountain above it.

This indicates an incremental, slow-moving landslide is already taking place above the fjord, but if the rock face were to suddenly give way, the consequences could be dire.

Although it's remote, this is an area that's frequented by commercial and recreational boats, including cruise ships.

"It was hard to believe the numbers at first," one of the researchers, geophysicist Chunli Dai from the Ohio State University told NASA's Earth Observatory.

"Based on the elevation of the deposit above the water, the volume of land that was slipping, and the angle of the slope, we calculated that a collapse would release 16 times more debris and 11 times more energy than Alaska's 1958 Lituya Bay landslide and mega-tsunami."

If the team's calculations are correct, such a result borders on the unthinkable, because the 1958 episode – likened by eyewitnesses to the explosion of an atomic bomb – is often thought to be the tallest tsunami wave in modern times, reaching a maximum elevation of 524 meters (1,720 feet).

A much more recent slope failure event in 2015 in Taan Fiord to the east produced a tsunami reaching as high as 193 meters (633 ft), and the researchers say these failures can be brought about by numerous causes.

"Slopes like this can change from slow creeping to a fast-moving landslide due to a number of possible triggers," the May report explains.

"Often, heavy or prolonged rain is a factor. Earthquakes commonly trigger failures. Hot weather that drives thawing of permafrost, snow, or glacier ice can also be a trigger."

Since the report's release earlier in the year, subsequent landslide analysis has suggested little or no movement of land masses on the slope, although in itself that doesn't tell us much, since research shows that the rock face has been shifting since at least 50 years ago, at some points speeding up, while slowing down at others.

While these kinds of subtle variations are still being investigated, the overall view is that the speed of glacier retreat increases the probability of more dramatic slope failures.

"When the climate changes, the landscape takes time to adjust," co-author of the letter and geologist Bretwood Higman from nonprofit Ground Truth Alaska told The Guardian.

"If a glacier retreats really quickly it can catch the surrounding slopes by surprise – they might fail catastrophically instead of gradually adjusting."

Ongoing monitoring by numerous organizations – including ADNR, the National Oceanic and Atmospheric Administration, and the US Geological Survey – is keeping tabs on developments at Prince William Sound, to track movements above the Barry Glacier, and to refine predictions of what the fallout from a mega-tsunami would be.

Preliminary modeling from the May report, which hasn't yet been peer-reviewed, suggests a tsunami reaching hundreds of feet in elevation along the shoreline would result from a sudden massive failure, propagating throughout Prince William Sound, and into bays and fjords far from the source.

Perhaps the bigger takeaway is that the impacts of relatively rapid glacier retreats in the era of climate change could pose similar kinds of landslide and tsunami threats in many other places around the world, not just in Alaska.

"It's really pretty terrifying," Higman told Columbia University's GlacierHub blog in May, likening the environmental risks to volcanoes – something that humanity has understood to be a dangerous, unpredictable geohazard for much, much longer.

"Maybe we're entering a time now where we need to look at glaciated landscapes with the same kind of glasses."

The findings are available on the ADNR website.

This article was originally published by ScienceAlert. Read the original article here.

If New York City were built 170 million years ago, when dinosaurs roamed the Earth, Africa would have been a short boat ride away. 

During the Jurassic period, the supercontinent Pangaea — which formed tens of millions of years prior — would have been slowly splitting apart, the continents drifting toward their present-day positions, according to a new online interactive map.

The interactive map, designed by software engineer Ian Webster, visualizes how Earth's continents evolved from about 750 million years ago to today, sweeping the user from a time when glaciers painted the planet white and an array of single-celled organisms such as green algae emerged, to a time when humans and climate change have become the globe's biggest threat.

Related: 50 interesting facts about planet Earth

Webster built this digital globe while studying plate tectonics — a theory that the Earth's outer shell is divided into pieces that move over the mantle with time, dragging continents with them. "I found that the data was difficult to consume and most interactive models were a bit dated or not generally accessible," Webster told Live Scinece. "Once I had the idea, I built most of the project while on a long international flight."

The map is built as a web application based on geological models created by geologist and paleogeography Christopher Scotese. The site uses a software called GPlates, developed by Caltech and the University of Sydney and used by geologists to visualize plate tectonic reconstructions through time.

The user can type in the name of a city to see where that city stood on the planet millions of years ago. For example, 600 million years ago, the land that was to become Paris was hidden underwater; then by 200 million years ago, Paris had shifted to a spot near Canada. The model also lets users jump to different timepoints of firsts for the planet, such as when the "first" multicellular life forms appeared or when the first flowers and hominids appeared. 

"One of my favorite parts is seeing how complex life developed relatively recently in geological terms," Webster said. While the Earth formed 4.5 billion years ago, the first land plants only emerged around 430 million years ago, he added. "I enjoy seeing how the Appalachian Mountains developed," he said. "They used to be as high as the Himalayas and have eroded over the eons."

Originally published on Live Science.

The Greenland Ice Sheet has reached a point of rapid retreat that it couldn't recover from even if global temperatures stopped rising instantly. 

This Arctic ice sheet is the second-largest ice sheet in the world, after the one that blankets Antarctica. It covers the majority of Greenland and melts into the seas via outlet glaciers, which have been rapidly losing ice for decades. Now, new research finds that today's glacial ice loss is 14% greater than it was between 1985 and 1999. The ice sheet is losing approximately 500 gigatons of ice each year, more than is replenished by annual snowfall. 

Projecting that trend forward, the ice sheet is set to lose mass 99 out of every 100 years, researchers reported Aug. 13 in the journal Nature Communications Earth & Environment. 

"Glacier retreat has knocked the dynamics of the whole ice sheet into a constant state of loss," study co-author Ian Howat, an Earth scientist at The Ohio State University, said in a statement. "Even if the climate were to stay the same or even get a little colder, the ice sheet would still be losing mass."

Related: 10 signs Earth's climate is off the rails

Increasing melt

Greenland's ice sheet has long been in peril. In January 2019, researchers reported in the journal Proceedings of the National Academy of Sciences that the ice sheet was losing ice at four times the rate it was in 2003. Other researchers have found that the ice sheet is sliding on its underlying bedrock faster than expected. This sliding can move ice from the cold interior of Greenland to the warmer edges, where it melts faster.

The new study combined three decades of satellite imagery with data from airplane surveys from Operation IceBridge,providing a detailed timeline of ice thickness, ice flow, ice elevation and the location of the calving front of the ice sheet — the line where the glaciers hit the sea and lose ice through the calving of icebergs. This method allowed the researchers to look at both seasonal changes in ice discharge as well as longer trends. 

What they found was an increase of about 60 gigatons of ice loss a year between 2007 and 2018 compared with the period between 1985 and 1999. All told, the ice sheet has lost 4,200 gigatons of ice since 1985.

There are regional differences, with some of the accelerating ice retreat between 2001 and 2005 driven by glaciers in the southeastern part of Greenland moving from relatively shallow parts of the seafloor into deeper sections, where warm water can more easily circulate beneath them and melt them.

Ice-free future?

But regardless of the region of Greenland, the retreat of a glacier by 0.6 miles (1 kilometer) is consistently associated with a 4% to 5% increase in the rate of ice discharge from that glacier. Because these sheets are already retreating, further ice loss is baked in, even in a hypothetical situation in which temperatures stop rising.

"Glaciers have been sensitive to seasonal melt for as long as we've been able to observe it, with spikes in ice discharge in the summer," study lead author Michalea King, a researcher at The Ohio State University's Byrd Polar and Climate Research Center, said in the statement. "But starting in 2000, you start superimposing that seasonal melt on a higher baseline — so you're going to get even more losses."

With the ice sheet set to lose more ice than it gains each year, it might seem like the end of the Greenland Ice Sheet. But that future has yet to be written, Potsdam University physicist and climate scientist Stegan Rahmstorf noted on Twitter. Eventually, he said, the ice retreat will pull the ice sheet away from the ocean. At that point, warm ocean waters will stop melting the ice, and the glaciers will stop calving. The Greenland Ice Sheet will become an entirely land-based entity. When that occurs, a new dynamic will set in: It will be a race between the rate of the surface melt of the ice and the annual snowfall that decides when and whether the ice sheet disappears. 

"Thus, Greenland ice loss is a real concern — already today it contributes a lot to sea-level rise," Rahmstorf wrote. "And Greenland does have a tipping point where the ice sheet becomes doomed to total loss. But the new paper by King et al. does not say anything about whether this has been crossed."

Originally published on Live Science.

On frosty Ellesmere Island, where Arctic Canada butts up against the northwestern edge of Greenland, two once-enormous ice caps have completely vanished, new NASA imagery shows.

It's no mystery where the caps, known as the St. Patrick Bay ice caps, went. Like many glacial features in the Arctic — which is warming at roughly twice the rate of the rest of the world — the caps were killed by climate change. Still, glaciologists who have studied these and other ice formations for decades are unnerved by just how quickly the caps disappeared from our warming planet.

"When I first visited those ice caps, they seemed like such a permanent fixture of the landscape," Mark Serreze, director of National Snow and Ice Data Center (NSIDC) in Colorado, said in a statement. "To watch them die in less than 40 years just blows me away."

Related: Pink 'watermelon snow’ threatens major Italian glacier

Ice caps are a type of glacier that cover less than 19,300 square miles (50,000 square kilometers) of land on Earth, according to the NSIDC. These frosty domes typically originate at high altitudes in polar regions and blanket everything beneath them in ice (unlike ice fields, which can be interrupted or diverted by mountain peaks). The loss of Earth's ice caps not only contributes to sea-level rise, but also decreases the amount of reflective white surfaces on the planet, leading to more heat absorption, the NSIDC wrote.

The St. Patrick Bay ice caps sat about 2,600 feet (800 meters) above Ellesmere Island's Hazen Plateau in Nunavut, Canada, where they existed for hundreds of years. Researchers aren't sure how large the caps were at their maximum extent, but when a team investigated in 1959 the caps covered about 3 square miles (7.5 square km) and 1.2 square miles (3 square km), respectively. (For comparison, the smaller one was about as big as Central Park in New York City.)

When researchers studied the caps again in 2017, the formations had shrunk to just 5% of their former sizes. Serreze, the lead author of the 2017 study, published in the journal The Cryosphere, predicted that the caps would vanish completely within five years.

Now here we are, two years ahead of schedule.

"We've long known that as climate change takes hold, the effects would be especially pronounced in the Arctic," Serreze said. "But the death of those two little caps that I once knew so well has made climate change very personal. All that's left are some photographs and a lot of memories."

The new satellite images, showing the Hazen Plateau's barren peaks, come from NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which imaged the island on July 14, 2020. Meanwhile, in nearby Greenland, ice loss has increased sixfold in the last 30 years. There's no question about it: Earth's climate is off the rails.

Originally published on Live Science.

A pink invader is threatening Italy's massive Presena glacier.

The Alpine glacier, once the site of World War I battles between the Kingdom of Italy and the Austro-Hungarian Empire and now an outdoor and skiing destination, seems to have caught a bad case of "watermelon snow," according to a CNN report. The pink hue comes from algae growing on the ice. Though the itty-bitty algae doesn't damage the glacier directly, it makes the normally white surface darker, allowing it to absorb more light from the sun. That absorbed light heats the glacier, speeding up its rate of melt. At 10,068 feet (3,069 meters) above sea level, the glacier has lasted intact for millennia through the summers.

Biagio Di Mauro, a researcher at the Institute of Polar Sciences at Italy's National Research Council, told CNN that the microscopic plant species Chlamydomonas nivalis likely caused the sudden pink hue. The algae is common in the Alps, but low winter snowfall seems to have combined with high spring and summer temperatures to create ideal conditions for a major bloom.

Related: Time-lapse images of retreating glaciers

Presena glacier conservators have been using massive sheets of textiles in the summer to reflect light off the glacier and back into space. But that does not cover all the ice.

Glaciers all over the world are shrinking at astonishing rates due to climate change. In the United States, many major glaciers that have existed for thousands of years, could be gone within decades according to the U.S. Geological Survey (USGS).

The USGS notes that glaciers are often integral parts of their local ecosystems, providing cool water for fish downstream, supporting agriculture and providing key drinking water sources for human populations. Without glaciers, water would be more scarce, even as droughts and wildfires become more common due to climate change.

Related: The vanishing glaciers of Europe's Alps

One of the most significant retreating glaciers in the world is Denman glacier in Antarctica, Live Science previously reported. The 12-mile-wide (20 kilometers) ice stream to the continent's east has retreated 3 miles (5 km) between 1996 and 2018. A canyon below the glacier may be accelerating Denman's retreat, risking a feedback loop that could entirely melt the giant block of ice. If all of Denman's ice flowed back into the ocean, sea levels would rise an average of 5 feet (1.5 m) worldwide.

Originally published on Live Science.

Archaeologists recently documented a rare treasure trove of Viking Age objects littering a long-forgotten mountain pass, including the remains of a dog wearing its collar and leash.

As climate change melts Norway's glaciers, pockets of history hidden for centuries or millennia are finally seeing the light of day. Melting along a high-altitude trail in the Lendbreen glacier has revealed hundreds of artifacts dating to the Viking Age, the Roman Iron Age and even the Bronze Age.

Remarkably well-preserved items littered the winding path, including clothing and shoes, a variety of tools and riding gear, and animal bones and dung. They offer clues about daily life, and hint at the challenges and importance of mountain travel in this region, according to a new study published online April 16 in the journal Antiquity.

Related: Fierce fighters: 7 secrets of Viking seamen

"A lost mountain pass is a dream discovery for us glacial archaeologists," lead study author Lars Pilø, co-director of the Glacier Archaeology Program (GAP), said in a statement. A collaboration between the Innlandet County Council and the Museum of Cultural History at the University of Oslo in Norway, GAP recovers and identifies historical artifacts exposed by disappearing Norwegian glaciers. 

The ice patch at the Lendbreen site extends from about 5,500 to 6,300 feet (1,690 to 1,920 meters) above sea level, and the mountain pass rises to nearly 6,500 feet (1,973 m) above sea level, researchers reported. Melt at Lendbreen in 2011 revealed the first evidence of the long-hidden trail, with cairns (human-made piles of stone) marking the route and a shelter at the highest point. 

In the new study, scientists documented discoveries that appeared between 2011 and 2015, preserved by the dry, frozen climate and protected by layers of ice (before being exposed). Among the objects were shoes made of hide; a woven mitten and more than 50 pieces of fabric; a walking stick inscribed with runes; a wood-handled knife; horseshoes and sled pieces; and bones from pack horses.

"The preservation of the objects emerging from the ice is just stunning," study co-author Espen Finstad, an archaeologist with the Department of Cultural Heritage in Lillehammer, Norway, said in the statement.  

Dead animals and broken tools were likely abandoned along the path by the travelers, while tools in good condition may have simply been lost, according to the study. The presence of usable clothing among the discarded objects is more puzzling, but these items may have been thrown away by people who were suffering from severe hypothermia, which can cause irrational behavior, the researchers wrote.

Carbon dating of approximately 60 objects indicated that the pass was actively used from around A.D. 300 to A.D. 1500. Some objects, such as a ski and an arrow, dated to the Bronze Age (1750 B.C. to 500 B.C.), and several artifacts were even older. But the items that were most abundant dated to around A.D. 1000 — the Viking Age — suggesting that the mountain pass was busiest during this period. 

Related: Photos: Vikings accessorized with tiny metal dragons

Unlike many other ancient mountain passes that are known from the Alps and the Himalayas, this route was likely busiest when snow and ice were abundant, as the route would have been difficult for pack animals and sleds to navigate when rocks were bare, according to the study. 

By sifting through the objects, scientists reconstructed how people used the path and how that changed over time. What was once a high-traffic roadway during the Viking Age waned in popularity and was all but abandoned by the 16th century, possibly due to climate change-related melting, economic upheaval and the arrival of pandemics from Europe, the researchers wrote.

Another substantial melt event at Lendbreen in 2019 revealed even more intriguing artifacts that are yet to be scientifically described, including the leashed dog remains, "and a wooden box with the lid still on," Finstad said.

• Photos: A man, a horse and a dog found in Viking boat burial
• Photos: 10th-century Viking tomb unearthed in Denmark
• Image gallery: Viking voyage discovered

Originally published on Live Science.

It's easy to forget that Antarctica is technically a desert, until you see it without snow.

A new pair of satellite images shared by NASA's Earth Observatory makes that stark reality clear as ice. NASA's Landsat-8 satellite snapped the two images of Eagle Island (a small island off Antarctica's northwest tip) on Feb. 4 and Feb. 13, 2020, bookending a period of record high temperatures in the southernmost continent. Between the two images, a significant amount of the island's glacial ice disappeared, revealing huge swaths of the barren brown rock underneath.

According to glaciologist Mauri Pelto, a professor of environmental science at Nichols College in Massachusetts, the island lost about 20% of its seasonal snow accumulation in just a few days.

"You see these kinds of melt events in Alaska and Greenland, but not usually in Antarctica," Pelto told NASA.

Related: One of Antarctica's fastest-shrinking glaciers just lost an iceberg twice the size of Washington, D.C.

The melt coincided with not one, but two record-high temperatures recorded on Antarctica this month. On Feb. 6, a research station on the northern edge of the Antarctic Peninsula (the finger of land on the continent's northwest tip, closest to South America) recorded a new record-high temperature of 64.9 degrees Fahrenheit (18.3 degrees Celsius) — surpassing the previous record of 63.5 F (17.5 C), set in March 2015. 

Days later, on Feb. 9, researchers on the nearby Seymour Island saw their thermometers hit 69.35 F (20.75 C), setting another all-time high for the continent. (For comparison, that's about the same temperature reported in Los Angeles, on the same day. Balmy!)

As the new images show, those high temperatures caused significant melting on nearby glaciers. According to Pelto, Eagle Island lost nearly 1 square mile (1.5 square kilometers) of snowpack to the heat, creating several large ponds of bright blue meltwater at the island's center. 

While every season has its highs, this summer has been especially warm for Antarctica, Pelto said. The continent has already seen two heatwaves this season — one in November 2019 and one in January 2020 — reminding us that significant melt events like these are becoming more common as global warming continues unchecked. 

• Images of melt: Earth's vanishing ice
• The reality of climate change: 10 myths busted
• Top 10 ways to destroy Earth

Originally published on Live Science. 

Antarctica is the remotest part of the world, but it is a hub of scientific discovery, international diplomacy and environmental change. It was officially discovered 200 years ago, on Jan. 27, 1820, when members of a Russian expedition sighted land in what is now known as the Fimbul Ice Shelf on the continent's east side.

Early explorers were drawn there by the mythology of Terra Australis, a vast southern continent that scholars imagined for centuries as a counterweight to the Northern Hemisphere. Others sought economic bounty from hunting whales and seals, or the glory of conquering the planet's last wilderness. Still others wanted to understand Earth's magnetic fields in order to better navigate the seas.

I am a geologist who specializes in understanding the timing and extent of past ice ages. Much of my work focuses on the glacial history of Antarctica, and I've been privileged to conduct five field seasons of research there.

Related: Antarctica: The Ice-Covered Bottom of the World (Photos)

For the next two years I'll be working with a field team made up entirely of undergraduate students from Vanderbilt University to determine whether the East Antarctic Ice Sheet changes flow patterns as it changes shape. All of the research these budding scientists conduct will be done under the auspices of the Antarctic Treaty, a global agreement that promotes scientific cooperation and environmental protection.

Frozen but abundant

Antarctica separated from South America 35 million years ago, and its climate started to change. It began to grow ice sheets — masses of glacial land ice covering thousands of square miles. As plate tectonics shifted other continents, Antarctica became colder and drier. For the past 14 million years, it has been the frigid continent that persists today.

Antarctica is the only continent that was literally discovered, because it has no native human population. British explorer Sir James Cook circumnavigated the continent in 1772-1775, but saw only some outlying islands. Cook concluded that if there were any land, it would be "condemned to everlasting regidity by Nature, never to yield to the warmth of the sun."

Related: Facts About Antarctica: The Southernmost Continent

Cook also reported that Antarctic waters were rich with nutrients and wildlife. This drew sealers and whalers, mainly from England and the United States, who hunted the region's fur seals and elephant seals to near-extinction in the following decades. This hunting spree led to the discovery of the Antarctic mainland and its ice sheets, the largest in the world.

Reading the ice

Today, the combined East and West Antarctic ice sheets hold 90% of the world's ice, enough to raise global sea levels by roughly 200 feet (60 meters) if it all melted. Antarctica is the coldest, highest, driest, windiest, brightest, and yes, iciest continent on Earth. And 200 years of research has shown that it is a key component of Earth's climate system.

Despite the appearance that it is an unchanging, freeze-dried landscape, my research and work by many others has shown that the East Antarctica Ice Sheet does slowly thin and thicken over millions of years. Interestingly, my data also suggest that as the ice advances and retreats, it moves in the same patterns each time. Put another way, the ice flows over the same land each time it advances.

While East Antarctica adds and loses ice slowly, it is so large that it is a major contributor to sea level rise. Understanding how the ice has changed in the past is key to predicting how much and how fast it will melt in the coming years.

These questions are especially important in West Antarctica, where the bottom of the ice sheet is below sea level, making it very susceptible to changes in sea level and ocean temperature. By itself, the West Antarctic ice sheet has the potential to raise sea level by 16 feet (5 meters) if it collapses.

As climate change raises global sea levels, parts of the West Antarctica Ice Sheet, such as the Thwaites and Pine Island Glaciers, are particularly vulnerable to collapse. At the end of the last ice age, parts of West Antarctica thinned by an average of 1.5 to 3 feet (0.5 - 1 meters) per year. Today with GPS, satellite and airborne measurements, scientists are seeing parts of West Antarctica thin by 3 to 20 feet (1 to 6 meters) per year.

We also know from the geological record that this ice sheet is capable of rapid collapses, and has sometimes thinned at rates in excess of 30 feet (10 meters) per year. Recent models show sea level could rise by 1 meter by 2100 and 15 meters by 2500 if greenhouse gas emissions continue to rise at current rates and the ice sheet experiences a rapid collapse, as it has in the past.

Finding inspiration in scientific diplomacy

Despite the potential for environmental disaster in Antarctica, the continent also offers evidence that nations can collaborate to find solutions. The Antarctic Treaty System is the world's premier example of peaceful and scientific international cooperation.

This landmark accord, signed in 1961, sets aside Antarctica for peaceful and scientific purposes and recognizes no land claims on the continent. It also was the first non-nuclear accord ever signed, barring use of Antarctica for nuclear weapons testing or disposal of radioactive waste.

The great Antarctic explorer Sir Ernest Shackleton said that "optimism is true moral courage," and the authors of the Antarctic Treaty were certainly courageous optimists. They were encouraged by the success of the 1957-1958 International Geophysical Year, a worldwide program of scientific research during which 12 countries built over 50 bases in Antarctica, including McMurdo Station and the Amundsen-Scott South Pole Station.

Under the treaty, scientists from North Korea, Russia and China can freely visit U.S. research stations in Antarctica. Researchers from India and Pakistan willingly share their data about Antarctic glaciers.

Thanks to the Antarctic Treaty, 10% of Earth's land surface is protected as a wildlife and wilderness refuge. I have set foot in places in Antarctica where I know no one has ever been before, and the treaty sets areas aside that no one will ever visit. Antarctica's landscapes are unlike anywhere else on Earth. The best comparison may be the Moon.

Yet in these stark environments, life finds a way to persist — showing that there are solutions to even the most daunting challenges. If Antarctica has taught us anything in 200 years, it's that we can cooperate and collaborate to overcome problems. As Ernest Shackleton once said, "Difficulties are just things to overcome, after all."

[ Thanks for reading! We can send you The Conversation's stories every day in an informative email. Sign up today. ]

• 50 Amazing Facts About Antarctica
• In Photos: Antarctica's Larsen C Ice Shelf Through Time
• Icy Images: Antarctica Will Amaze You in Incredible Aerial Views

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

For the past 15,000 years, a glacier on the northwestern Tibetan Plateau of China has hosted a party for some unusual guests: an ensemble of frozen viruses, many of them unknown to modern science.

Scientists recently broke up this party after taking a look at two ice cores from this Tibetan glacier, revealing the existence of 28 never-before-seen virus groups. 

Investigating these mysterious viruses could help scientists on two fronts: For one, these stowaways can teach researchers which viruses thrived in different climates and environments over time, the researchers wrote in a paper posted on the bioRxiv database on Jan. 7. 

Related: Photographic Proof of Climate Change: Time-Lapse Images of Retreated Glaciers

"However, in a worst-case scenario, this ice melt [from climate change] could release pathogens into the environment," the researchers wrote in the study, which has not yet been peer-reviewed. If this happens, it's best to know as much about these viruses as possible, the researchers wrote.

Icy research

Studying ancient glacial microbes can be challenging. That's because it's extremely easy to contaminate ice core samples with modern-day bacteria. So, the researchers created a new protocol for ultraclean microbial and viral sampling. 

In this case, the two ice core samples from the Guliya ice cap on the Tibetan Plateau were collected in 1992 and 2015. However, at those times, there weren't any special measures taken to avoid microbial contamination during the core drilling, handling or transport. 

In other words, the exterior of these ice cores was contaminated. But the insides were still pristine, the researchers wrote in the study. To access the inner part of the cores, the researchers set up shop in a cold room — the thermometer was set at 23 degrees Fahrenheit (minus 5 degrees Celsius) — and used a sterilized band saw to cut away 0.2 inches (0.5 centimeters) of ice from the outer layer. Then, the researchers washed the ice cores with ethanol to melt another 0.2 inches of ice. Finally, they washed the next 0.2 inches away with sterile water. 

After all of this work (shaving off about 0.6 inches, or 1.5 cm of ice), the researchers reached an uncontaminated layer that they could study. This method held up even during tests in which the researchers covered the outer layer of the ice with other bacteria and viruses. 

The experiment revealed 33 groups of virus genuses (also known as genera) in the ice cores. Of these, 28 were previously unknown to science, the researchers said. "The microbes differed significantly across the two ice cores," the researchers wrote in the study, "presumably representing the very different climate conditions at the time of deposition."

It's no surprise that the glacier held these mysterious viruses for so long, researchers said.

"We are very far from sampling the entire diversity of viruses on Earth," Chantal Abergel, a researcher in environmental virology at the French National Centre for Scientific Research, who wasn't involved with the study, told Vice. 

As human-made climate change melts glaciers the world over, these viral archives could be lost, the researchers noted. Research into ancient viruses "provides a first window into viral genomes and their ecology from glacier ice," the researchers wrote in the study, "and emphasizes their likely impact on abundant microbial groups [today]."

• In Photos: The Vanishing Glaciers of Europe's Alps
• Images of the Himalayas and the Tibetan Plateau
• Tiny & Nasty: Images of Things That Make Us Sick

Originally published on Live Science.

SAN FRANCISCO — The glaciers surrounding Mount Everest have lost far more ice than once thought, declassified spy satellite photos have revealed.

Using these decades-old images — along with recently-collected data — researchers generated digital surface-elevation models of the glaciers, creating a highly detailed record of melt. From 1962 to 2018, the glaciers along Mount Everest's flanks had shrunk significantly from the top down, according to research presented on Dec. 13, 2019, here at the annual meeting of the American Geophysical Union.

Decades-old images

During the late 1950s, U.S. intelligence officials devised a plan to take to the skies to peek behind the Iron Curtain and spy on the Soviet Union. A secret satellite surveillance mission, code-named Corona, launched in 1960 and ended in 1972, according to the CIA website. This joint effort, helmed by the CIA, the U.S. Air Force and private industry experts, collected photographs of locations across Eastern Europe and Asia.

Related: Photographic Proof of Climate Change: Time-Lapse Images of Retreating Glaciers

By the time these images were declassified, in 1995, the mission had amassed more than 800,000 photos. These included numerous views of the Himalayas, offering scientists an unprecedented glimpse of how the region's glaciers had changed over time, said Tobias Bolch, a lecturer for remote sensing with the School of Geography and Sustainable Development at the University of St. Andrews in the United Kingdom. 

Bolch and his colleagues combined analysis of these satellite photos with aerial images and modern satellite views, to visualize glacier ice mass loss since the 1960s. 

As Earth warms, many glaciers' outermost boundaries visibly retreat and expose the rock underneath, so it's easy to spot where ice has been lost. For the new investigation, the scientists sought a missing piece of the puzzle: how loss of ice might affect a glacier's height, Bolch told Live Science. They found the first signs of significantly reduced ice dating back to the 1960s.

"When we now look at the entire area, we see a clear increase in mass loss while it was in the period of 1962 to 1969, around 20 centimeters [8 inches] per year," he said.

Overall, the researchers found that Rongbuk and Khumbu glaciers, where Everest base camps are located, had thinned by more than 260 feet (80 meters) over 60 years, while Imja glacier lost more than 300 feet (100 m) of ice during the same timespan. 

The researchers also found that ice loss sped up in recent decades, with the acceleration beginning in the 1980s, Bolch said.

This new data about vanished ice suggests that the region's supply of stored fresh water is draining away quicker than computer models have predicted. Runaway glacial ice loss could also destabilize popular mountaineering trails near Everest, heightening the risks for hikers and climbers, Bolch said.

• In Photos: The Vanishing Glaciers of Europe's Alps
• Images of Melt: Earth's Vanishing Ice
• Ice Watch: Satellites Reveal How Glaciers Creep and Crawl

Originally published on Live Science.

A robotic submarine is about to descend into a dark, water-filled cavern in Antarctica, to try to find out why one of the continent's largest glaciers is melting so fast.

In the next few days, scientists will lower the torpedo-shaped robot, dubbed Icefin, into a nearly 2,000-foot-long (600 meters) borehole in the ice of Thwaites Glacier in West Antarctica. Previously, scientists used Icefin robots to study the sea life beneath the ice in the Ross Sea off of Antarctica, but this new project has a different purpose.

A key aspect of the robot's mission will be to study the glacier's "grounding line," the point where it separates from the continental bedrock and starts to float on the waters of the Amundsen Sea.

The Thwaites Glacier covers more than 74,000 square miles (192,000 square kilometers) — an area larger than Florida — and is more than 900 miles (1,500 km) from the nearest U.S. and British Antarctic research bases. It's one of Antarctica's fastest-melting glaciers, having lost an estimated 595 billion tons (540 billion metric tons) of ice since the 1980s. Observations indicate that the glacier is now melting even faster than before, and scientists want to find out why.

Related: Images of Melt: Earth's Vanishing Ice

They are also concerned that the melting of the large coastal glacier could expose some inland glaciers nearby to further melting, causing sea levels to rise by up to 6 feet (2 m).

Thwaites Glacier could be "a keystone to triggering ice loss from neighboring portions of West Antarctica," said Paul Cutler, program director of glaciology, ice core science and geomorphology at the National Science Foundation. "The question is, how much sea level rise, and how fast?"

Cutler is the U.S. program director for the International Thwaites Glacier Collaboration (ITGC), a multi-year study involving more than 60 scientists from several countries.

The submarine robot project, t,named MELT, is one of eight major ITGC projects on the Thwaites Glacier supported by the U.S. Antarctic Program and the British Antarctic Survey. . 

Melting through the ice

The MELT project scientists flew out to the Thwaites Glacier a few weeks ago and are now camped out on its eastern ice tongue. They have melted and drilled out a 20-inch-wide (50 centimeters) access hole through the ice near its grounding line, Cutler told Live Science in an email. 

In the coming days, they will lower the Icefin robot through the ice to explore a vast cavity, two-thirds of the area of Manhattan, which researchers using ice-penetrating radar discovered beneath the glacier last year.

Icefin is equipped with high-definition video cameras, sonar and instruments for monitoring water flow, salinity, oxygen and temperature.

After the scientists deploy Icefin, they plan to recover it three or four days later, before the hole freezes over.

Icefin will send back live pictures to the scientists so they can guide the robot to the glacier's grounding line. Once there, it will take sediment samples and measure the amount of fresh water flowing out to sea from the glacier as it melts.

ITGC scientists have only a few weeks left before the weather on the remote glacier starts to get worse with the approach of the southern polar winter. The final part of the ITGC operation this season will take place in late January, when a U.S. research ship leaves Chile for the Amundsen Sea to collect data from the ocean floor near Thwaites Glacier, Cutler said.

The ITGC is the largest joint U.S.-U.K. scientific operation undertaken in Antarctica in the past 70 years, and it has required an extraordinary amount of planning to deal with the freezing weather and remote location of Thwaites Glacier.

It took the U.S. Antarctic Program and the British Antarctic Survey two years to prepare the logistics of the operation, and the scientific projects were planned long before that. "Aa program of this magnitude is years in the making, Cutler said."

The implications of the project, however, are not Earthbound. Engineers hope that the technology they're using for Icefin one day will be used to search for life in other ice-covered oceans in the solar system, such as the liquid oceans thought to exist beneath the icy crusts of Saturn's moon Enceladus and Jupiter's moon Europa.

• 50 Amazing Facts About Antarctica
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• Icy Images: Antarctica Will Amaze You in Incredible Aerial Views

Originally published on Live Science.

The southernmost continent is an awesome place, in the old-fashioned sense of the word. Precipitous mountains, grinding glaciers and icebergs of every configuration, and a surprising range of colors make up Antarctica's wondrous landscape. 

And because the continent is so remote and foreboding, much of this landscape remains unknown. With new tools and new expeditions, scientists are peering into Antarctica's nooks and crannies and even its subsurface, discovering a world that seems unimaginable from more temperate climes. Here are some of the secrets Antarctica revealed in 2019. 

A giant and growing void 

Imagine an ice cave two-thirds the area of Manhattan and nearly 1,000 feet (300 meters) tall. Hard to envision? It's real, and it's under the Thwaites Glacier in West Antarctica. 

The gap between the glacier and the bedrock below was discovered this year by NASA scientists, who say that much of the void was formed from melt that occured in the last few years. Using ice-penetrating, satellite-based radar, they found a void that once held 15 billion tons (13.6 billion metric tons) of ice. The gap may be contributing to the glacier's movement and melt, researchers reported in the journal Science Advances. 

A surprising former resident

Long ago, Antarctica was a much warmer place, home to dinosaurs and lush plant life. Even before the dinosaurs roamed, an iguana-like Triassic reptile called the Antarctica home. 

Researchers announced the discovery of the reptile, dubbed Antarctanax shackletoni, this year. The 250 million-year-old creature was an archosaur, a precursor to the lineage that would branch into dinosaurs, pterosaurs and crocodilians. This animal probably grew to 4 to 5 feet (1.2 to 1.5 meters) long, and scuttled around what was then the Antarctic forest floor. 

...and a Loch Ness monster

Ancient Antarctica was also home to the world's heaviest elasmosaurid, a plesiosaur of the genus Aristonectes. Paleontologists discovered the long-necked sea creature on Antarctica's Seymour Island in 1989, but they weren't able to finish excavating the enormous fossil until 2017. They ultimately pulled 1,760 lbs. (800 kilograms) of fossilized bone off the island. After examining the specimen, the researchers described the beast this year for the first time.

In life, the Antarctic Loch Ness monster would have been 36 feet (11 m) long and weighed in at a bulky 15 tons (13.4 metric tons). The creature lived only a few tens of thousands of years before the Cretaceous-Paleogene extinction 66 million years ago, when an asteroid collided with Earth and wiped out the non-avian dinosaurs.

A rare lava lake

In modern times, Antarctica still holds surprises. Take Saunders Island, a volcanic protuberance in the South Sandwich Islands. The icy crag of Mount Michael, the island's volcanic summit, holds one of only eight lava lakes in the world. 

Scientists discovered the crater lake thanks to thermal imaging from satellite data. Unlike most exposed lava on the Earth's surface, the lake remains molten. Its temperature in the lake reaches between 1,812 and 2,334 degrees Fahrenheit (989 and 1,279 degrees Celsius).

Upside-down rivers

Antarctica's ice sheets are as complex on their undersides as they are up top. A new study published this year found that enormous under-ice rivers of warm water scour the continent's ice shelves from below. 

These ice shelves are the portion of the ice sheets that protrude over the ocean. Scientists observed certain areas of the sheets that seemed to sag, crack and sometimes melt through year after year. They found that these areas are undermined by warm ocean currents that flow like rivers, melting the ice above. 

Oddly shaped icebergs

Wind and water sculpt Antarctica's ice into strange shapes, but this takes the cake (and kind of looks like one): In October, scientists snapped aerial photos of floating rectangular 'bergs near the northern Antarctic Peninsula. 

The rectangular chunks were shards created by the calving of a huge iceberg, dubbed A68, off the Larsen C ice shelf in 2017. Erosion hadn't yet had time to smooth the rectangular icebergs' corners and straight edges. 

And ice that sings

A steady seismic hum animates Antarctica's ice – all the time. Humans can't hear the 5 hertz frequency, but researchers picked up the hum on sensors meant to detect vibrations in the ice. This subsonic singing is caused by the movement of wind against the ice, the researchers reported in October. The song changes subtly when the ice melts or when wind changes the shape of snow dunes, making the sound a possible way to track local changes remotely. 

"It's kind of like you're blowing a flute, constantly, on the ice shelf," lead study author Julien Chaput, a geophysicist and mathematician at Colorado State University in Fort Collins, said in a statement.

Strange particles

Antarctica's relative peace and quiet makes it a useful place for physicists to hunt for quick-moving cosmic rays and elusive elementary particles. Recently, though, the region's ice hasn't only been absorbing these particles from space, but seemingly spitting them out, too. 

Researchers aren't sure what to make of measurements from NASA's Antarctic Impulsive Transient Antenna and the IceCube observatory, both of which are designed to detect space-based phenomena. So far, the identity of the particles detected over Antarctica remains a mystery.

Extreme life

Antarctica — other than penguins, not much there, right? Well, maybe not. Under half a mile of ice just a few hundred miles from the South Pole, bacteria thrive. 

Researchers led by ecologist John Priscu at the University of Montana drilled into Lake Mercer beneath the West Antarctic ice sheet and found that it was full of life. They measured 10,000 bacterial cells per milliliter of lake water. 

That is only about 1% of the amount of ice in open-ocean water, but surprising for such a cold, sunless spot. Researchers say that these bacteria could provide clues about the kinds of life that might evolve on far-flung planets like Mars. 

And a very deep hole

As of January 2019, West Antarctica hosts a world record: the deepest hole ever drilled on the continent. A British Antarctic Survey-led project drilled the hole with the goal of monitoring changes within the area's ice sheet. Using hot water to melt a channel in the ice, the researchers drilled to a depth of 7,060 feet (2,152 meters). 

It's not the deepest hole ever drilled on Earth, by far. That honor goes to the Kola Superdeep Borehole in Russia, which penetrated 40,230 feet (12,262 m) into Earth’s crust. That borehole took 20 years to dig, compared with just 63 hours for the West Antarctic hole. 

Shackleton's lost ship — almost

In 1915, the Endurance, helmed by Sir Ernest Shackleton, slipped beneath the Weddell Sea, crushed by the Antarctic's relentless ice. Shackleton and his men abandoned the ship, which had been trapped in pack ice for months. They set off on a 720-nautical-mile journey in lifeboats toward South Georgia Island, where they were rescued. The crew recorded the last position of the Endurance, though, raising hopes that its wreck might someday be found. 

A 2019 expedition got close — but the Antarctic wasn't ready to release the Endurance just yet. On the final leg of its mission to the wreck site, the Weddell Sea Expedition lost its sea-going drone under the ice and had to call it quits. 

Red ice, green ice...?

Though ice is usually white or blue, Antarctica also hosts ice in some surprising hues. The famous Blood Falls in the McMurdo Dry Valleys is — as the name would indicate — an iron-rich red. And then there are the green icebergs. Researchers had never known until this year why some Antarctic icebergs are a striking shade of green, but now they have a theory: The hue may come from iron-oxide dust, carried by glacial ice into the sea. 

Icequakes demystified

Seismic sensors in Antarctica capture thousands of tiny earthquakes throughout the melt season. These quakes can't be felt by humans, but now scientists know why they're happening. When ice-covered puddles of water begin to re-freeze at night, the expansion of the water warps the “lid” of ice on top. With enough pressure, the film of ice breaks, creating a tiny tremor that is picked up on seismographs. Researchers are now working to figure out how this thaw-freeze-thaw cycle might play into the larger dynamics of the ice sheets. 

Gaping holes explained

Another Antarctic mystery: gaping holes in the ice called polynyas, which pop up even in winter, when the ice pack is at its thickest. 

In June, researchers reported that they might know why these polynyas exist in the sea ice. Using satellite tags attached to wild seals, the scientists gathered water data and compared it to the timing of polynyas opening and closing. They found that polynyas form when the combination of ocean currents and strong, stormy winds is just right. The polynyas also release a lot of heat from the underlying ocean, which may further influence local weather and wind patterns. 

Stardust older than the sun

Antarctica is fertile ground for meteorite hunters, because the space rocks that land there accumulate in glaciers and tend to become concentrated. One of these meteorites turned up something incredible, scientists reported in April. One of its grains, just 1/25,000 of an inch in size, is a speck of dust from a star explosion called a nova. The dust speck is older than the sun and holds clues to the composition of the early solar system. 

Earth's oldest ice

Antarctica's groaning ice sheets likely contain the oldest ice on Earth, and scientists are hunting it down. 

In April, researchers with the "Beyond EPICA-Oldest Ice" mission announced that they are starting a five-year project to drill into Little Dome C, a location near the Concordia research station on the Antarctic Plateau. About 1.5 miles (2.7 km) down, the team expects to find ice that has been frozen in place for between 800,000 and 1.5 million years. 

Originally published on Live Science.

Massive and meaty, the Taku Glacier in Alaska's Juneau Icefield was a poster child for the frozen places holding their own against climate change. As the largest of 20 major glaciers in the region and one of the single thickest glaciers in the world (it measures 4,860 feet, or 1,480 meters, from surface to floor), Taku had been demonstrably gaining mass and spreading farther into the nearby Taku river for nearly half a century, while all of its neighboring glaciers shrank. Now, it appears those glory days are over.

In a new pair of satellite photos shared by NASA's Earth Observatory, the slow decline of Taku Glacier has finally become apparent. Taken in August 2014 and August 2018, the photos show the icy platforms where the glacier meets the river retreating for the first time since scientists began studying Taku, in 1946. 

While the shrinkage is subtle for now, the results are nonetheless shocking. According to glaciologist Mauri Pelto, who has studied the Juneau Icefield for three decades, Taku was predicted to continue advancing for the rest of the century. Not only have these signs of retreat arrived about 80 years ahead of schedule, Pelto said, but they also snuff a symbolic flicker of hope in the race to understand climate change. Of 250 mountain (or "alpine") glaciers that Pelto has studied around the world, Taku was the only one that hadn't clearly started to retreat.

Related: Photographic Proof of Climate Change: Time-Lapse Images of Retreating Glaciers

"This is a big deal for me because I had this one glacier I could hold on to," Pelto, a professor at Nichols College in Massachusetts, told NASA. "But not anymore. This makes the score climate change: 250 and alpine glaciers: 0."

Pelto discovered Taku Glacier's retreat as part of a new study published Oct. 14 in the journal Remote Sensing. Using satellite data, Pelto looked at a region of the glacier known as the transient snow line, or the place where snow disappears and bare glacial ice begins. If a glacier loses more mass to melting than it gains from snow accumulation during a particular year, its snow line moves to higher altitudes. The relative position of this line can help researchers calculate changes in the glacier's mass from year to year.

Historical records show that between 1946 to 1988, Taku Glacier had been gaining mass and advancing (that is, growing) by about a foot per year. After that, the advancement began to slow and the ice started to thin a bit. From 2013 to 2018, advancement stopped altogether — then, in 2018, the glacier finally started to retreat. In that year, Pelto observed the greatest mass loss and the highest snow line in Taku glacier's history. Those changes coincided with the warmest July on record in Juneau, Pelto wrote.

While it was inevitable for even a glacier as thick as Taku to transition eventually from a period of advancement to one of retreat, those transitions generally result after decades of stability where the glacier's edge does not move at all. Taku's transition from growth to decay, meanwhile, seems to have lasted only a few years.

"To be able to have the transition take place so fast indicates that climate is overriding the natural cycle of advance and retreat that the glacier would normally be going through," Pelto said.

• Images of Melt: Earth's Vanishing Ice
• The Reality of Climate Change: 10 Myths Busted
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Originally published on Live Science.

A glacier in Patagonia that has lost half its length in 30 years may be the fastest-thinning glacier on the planet. 

The glacier, known as Hielo Patagónico Sur 12 (HPS-12), is perched in the Andes mountains in Chile. Researchers reporting in the journal Nature Geoscience in September found that HPS-12 has been losing thickness and retreating inland. According to their analysis of satellite data, the glacier lost 98 feet (30 meters) of ice thickness each year, on average, between 2000 and 2008, near its terminal end. At its fastest, the thinning occurred at a rate of 144 feet (44 m) per year, according to study co-author Etienne Berthier, a glaciologist at the University of Toulouse in France. The section where that thinning was recorded melted away entirely in 2018. 

Related: Images of Melt: Earth's Vanishing Ice

"To our knowledge, this is indeed the fastest observed rate of loss for a glacier," Berthier told NASA's Earth Observatory. 

The Earth Observatory released before-and-after photos yesterday (Oct. 29) showing the stunning ice loss. One satellite shot — taken on Jan. 27, 1985, by a tool on the Landsat 5 satellite — shows the ice of the glacier sweeping down from the mountainside in the Southern Patagonia Icefield. A comparison shot taken by the Operational Land Imager on the Landsat 8 satellite in January 2019 shows an entirely different world: The glacier hunkers into just a portion of its fjord, exposing a large section of bare rock. 

The glaciers of Peru and Chile are known as "tropical glaciers," a seeming oxymoron that signifies that the glaciers sit in Earth's midsection, rather than near the poles. Tropical glaciers are retreating rapidly. Research released in 2013 found that glaciers in the Andes have lost between 30% and 50% of their surface area since the 1970s. These glaciers are vulnerable to warming both from above (due to air temperatures) and below (due to ocean temperatures at the glacier terminus, or the end of the glacier that is advancing or retreating. 

Seasonal glacial melt provides water that feeds agriculture and industry, but as ice retreat hastens, that meltwater can also kill by causing floods and avalanches. As the ice disappears entirely, water in the Andes will become an increasingly scarce resource, according to Columbia University's Earth Institute.

Because the glaciers are incredibly remote, they are hard to study except via satellite. That's why HPS-12's status as the fastest-thinning glacier on Earth comes with an asterisk: There may be other glaciers that are disappearing even faster without humans having noticed, Berthier told the Earth Observatory. 

"There is still a lot to learn about patterns of glacier mass loss in remote regions," she said. 

• Images: Greenland's Gorgeous Glaciers
• Photographic Proof of Climate Change: Time-Lapse Images of Retreating Glaciers
• Photos of Melt: Glaciers Before and After

Originally published on Live Science.

Two cracks are growing in western Antarctica's Pine Island Glacier, and they are an ominous warning that major ice loss is on the way. 

This isn't the first major ice loss in recent years. Nearly a year ago, on Oct. 29, 2018, an iceberg measuring approximately 116 square miles (300 square kilometers) calved from the glacier, less than one month after a large crack appeared. 

Soon after the calving of iceberg B46, a chunk that accounted for 87 square miles (226 square km) of the October 2018 ice loss, the two new cracks appeared, said Mark Drinkwater, head of the Earth and Mission Sciences Division at the European Space Agency (ESA). 

These cracks were spotted in early 2019 by the ESA's Copernicus Sentinel-1 and Sentinel-2 satellites. 

Recent satellite observations reveal that the new cracks are growing, the ESA reported in a statement. Each of the cracks now measures around 12 miles (20 km) in length. Their expansion suggests the ice sheet is facing imminent and significant ice loss, according to the ESA.

Related: Photo Gallery: Antarctica's Pine Island Glacier Cracks

"Sentinel-1 winter monitoring of their progressive extension signals that a new iceberg of similar proportions will soon be calved," Drinkwater said in the statement. To put that into perspective, an iceberg that large would span more than twice the area of Paris.

Both Sentinel satellite missions perform polar observations. But Sentinel-1's paired orbiters are particularly useful for monitoring the status of ice at Pine Island Glacier, as these satellites use an imaging system called synthetic aperture radar (SAR) that can capture photos year-round, during winter's dark months and in any type of weather, according to the ESA. 

Like an icy tongue, Pine Island Glacier links the West Antarctic Ice Sheet to the Amundsen Sea. It is one of the fastest-retreating glaciers in Antarctica, and calving incidents have increased in recent years, NASA reported. Warming ocean currents are also melting the glacier from underneath, washing ice away faster than the glacier can replenish it, the ESA said. 

Prior to the 2018 calving, the glacier suffered two more massive ice losses in 2015 and 2017, raising concerns among glaciologists for the region's future stability.

"In terms of frequency, it's happening more than before," Seongsu Jeong, a postdoctoral researcher at the Byrd Polar and Climate Research Center at The Ohio State University, told Live Science in 2017.

• In Photos: The Vanishing Glaciers of Europe's Alps
• Images of Melt: Earth's Vanishing Ice
• Time-Lapse Images of Retreating Glaciers

 Originally published on Live Science. 

More than 100 scientists from 30 countries released a special report examining climate change impacts on the oceans and a less familiar but critically important part of the Earth: the cryosphere.

Ice sheets, ice caps and glaciers, the floating sea ice of the polar regions, lake ice, snow on the ground, and permafrost, permanently frozen ground in northern latitudes, all make up the cryosphere.

While snow and ice in our daily lives can, at times, be difficult to navigate and sometimes dangerous, people benefit greatly from the cryosphere. It helps cool our planet and controls global sea level. It affects ocean currents and storm patterns around the world. The fresh water stored in snow and ice provides drinking water and irrigates crops. I am a researcher who studies snow and ice, and the fact that the Earth is beginning to lose its cryosphere as a result of global warming climate should concern all of us.

Fresh water locked in massive ice sheets

The Greenland and Antarctic ice sheets contain 99% of the freshwater ice on the planet. These ice sheets, glaciers and ice caps around the world are losing mass and are contributing to sea level rise, putting coastal regions and low-lying islands around the world at risk.

The Tibetan Plateau is known as the "water tower" of Asia. The Mekong River, Yellow River, the Yangthze, Indus River and the Karnali all originate on the Tibetan plateau and are fed by snow and glacier melt and the water from these rivers supports hundreds of millions of people.

More locally, in the U.S. Mountain West, including the Cascades, Sierra Nevada and Rocky Mountains, the winter snowpack, water stored as ice and snow until spring, is the major source of water for agriculture, industry and municipal use. Like the ice sheets in the polar regions, evidence shows that the winter snowpack in the U.S. is shrinking. The economic impact to communities without enough cold weather and snow is numerous, whether it is a loss of winter sports such as skiing, snowmobiling and ice fishing or less water for fish or irrigation to grow food.

The threats of our shrinking cryosphere involve much more than impacts to local and regional economies, however. Much of our planet's snow and ice, located in the polar regions, is there because it is so cold. The bright white snow and ice cover functions like a mirror for the planet, reflecting back into space much of the Sun's energy that reaches the surface. The snow and ice reinforce the cold of the polar regions and their role as our planet's natural refrigerators. A warming Earth undermines the ability of snow and ice to moderate and stabilize the global climate.

The impact of thinning ice

In the Arctic, the North Polar region of Earth, much of the ocean is covered by floating sea ice, which forms when sea water freezes. This sea ice cover is shrinking. As the ice thins and melts, darker surfaces are exposed and absorb more of the Sun's energy. This leads to more warming and even more melting. This cycle of heat absorption, warming and melting, known as a positive feedback, is a factor in Arctic amplification — the observation that the Arctic is warming at least twice as quickly the rate as the globe as a whole.

The loss of the floating sea ice cover and the rapidly warming Arctic are causing a cascade effect through the Arctic food chain — from top predators like the polar bear to tiny phytoplankton that live throughout the world's oceans. The lives of the 4 million people who live in the Arctic are being disrupted in myriad ways.

The ice-diminished Arctic is opening up potential shipping lanes including the northern sea route along the Russian coast and the Northwest Passage through the channels of the Canadian Arctic archipelago, all islands north of Canada except Greenland. Oil and natural gas deposits under the Arctic seafloor are becoming more accessible. The potential for economic development in the region brings with it inevitable challenges of governance and conflict.

The global ice budget

But what is happening in the north won't just stay there. As the Arctic warms, it may disrupt the jet stream, the narrow band of strong west to east winds high in the atmosphere that influences weather, the tracks and intensity of storms in the middle latitudes of the Northern Hemisphere. Some scientists say that this is already happening.

And, as the Arctic's permafrost thaws, Arctic land will release stored carbon, in the form of carbon dioxide, and methane back to the atmosphere, potentially leading to further climate warming. The melting Greenland ice sheet is contributing to sea level rise in addition to melting Arctic ice caps and glaciers.

As our climate gets hotter, the cryosphere will continue to shrink and melt, and the impacts of losing it will likely only multiply. What we see today is just the beginning.

[ Like what you've read? Want more? Sign up for The Conversation's daily newsletter. ]

• Images of Melt: Earth's Vanishing Ice
• In Photos: The Vanishing Ice of Baffin Island
• In Photos: A Conveyor Belt for Arctic Sea Ice

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

Last spring, scientists came out with a dire prediction that an increasingly warming planet could melt most of the glaciers in the European Alps by 2100. The melting seems to have begun. 

Now, part of one of those glaciers is already at the brink of collapse, officials warned this week.

Italian officials have ordered the evacuation of mountain huts and closed down roads near the Planpincieux Glacier that sits on the slopes of the Grandes Jorasses mountain, in the Mont Blanc mountain range. The glacier lies along the French-Italian border, near the town of Courmayeur. But this giant beast is not sitting still.

The glacier is moving 20 to 24 inches (50 to 60 centimeters) a day on average, according to a report by the Valle d'Aosta regional government and the Italy-based nonprofit Fondazione Montagna Sicura (the Secure Mountain Foundation), which led to the warning. That means that 8.8 million cubic feet (250,000 cubic meters) of ice could potentially give way and cause powerful avalanches, according to a statement by the city of Courmayeur in Italy. 

Related: In Photos: The Vanishing Glaciers of Europe's Alps

The mayor of Courmayeur, Stefano Miserocchi, said global warming is to blame. "These phenomena testify once again how the mountain is in a phase of strong change due to climatic factors, therefore it is particularly vulnerable," Miserocchi said in the translated statement. "In this case, it is a temperate glacier particularly sensitive to high temperatures." 

Temperate glaciers, like the glaciers of the Alps, are generally residing at temperatures that are just about at the melting point of ice — meaning a small change in temperature can have a "major impact" on them, according to the U.S. Geological Survey. In a worst-case scenario, where average global temperatures rise by up to 8.6 degrees Fahrenheit (4.8 degrees Celsius) by 2100, 95% of the glacial ice in the Alps would disappear, according to a study published in April in the journal The Cryosphere. In the best-case scenario, where global warming is curbed before it reaches relentless levels, and global temperatures rise by less than 3.6 F (2 C), only two-thirds of the Alps glaciers would be expected to disappear.

As to the fate of this popular hiking destination … a waiting game. It's unclear when the collapse will happen, but officials note that the warning is precautionary and isn't a threat to tourist or residential areas, according to The Guardian. As to the fate of our planet … it shouldn't be a waiting game, scientists said in a big climate report released this week. Students around the world took to the streets last Friday (Sept. 20) to protest inaction on climate change and world leaders traveled to New York to participate in the U.N. Climate Change Summit. 

• 8 Ways Global Warming Is Already Changing the World
• In Photos: The Vanishing Ice of Baffin Island
• Images of Melt: Earth's Vanishing Ice

Originally published on Live Science.

The world's glaciers are melting and dumping water into the ocean. If you've read about climate change, you probably know this. But now, once again, the rate at which all that extra water is flowing into the ocean has to be revised upward. Researchers have revealed that ice on the submerged bottoms of ocean-edge glaciers may be melting at a much faster rate — possibly 100 times faster — than current models predict. And that could have serious implications for the rate at which the seas rise.

That's the conclusion of a new paper published today (July 26) in the journal Science. A research team focused on a tidewater glacier, a flowing slab of ice that reaches all the way to the ocean such that the front of the glacier is in the sea. They used sonar to study the melting around LeConte Glacier glacier in Alaska, studying how ice shapes at the bottom of the glacier changed over time. At the same time, they measured temperature, flow rate and salinity changes in the water around it. Their results showed that existing theories of how water melts off the bottom of tidewater glaciers were significantly underestimating how fast ice was turning into water.

"We measured both the ocean properties in front of the glacier and the melt rates, and we found that they are not related in the way we expected," Rebecca Jackson, an oceanographer at Rutgers University who was a postdoctoral researcher at Oregon State University during the project, said in a statement. "These two sets of measurements show that melt rates are significantly, sometimes up to a factor of 100, higher than existing theory would predict." [8 Ways Global Warming is Changing the World]

The bottoms of tidewater glaciers melt in two ways: Rushing "plumes" of rapidly melting water flow off the bottom of the glaciers in coherent patterns that scientists can detect relatively easily. And at the same time, a slower, "ambient" melting process is taking place. Scientists previously believed that this ambient melting accounted for just a small fraction of total melting, and tended to focus on the plumes. But Jackson and her team's work, which compared sonar data to the plume data, showed that this ambient melting has been underestimated by a factor of up to 100.

(A timelapse by Jason Amundson at the University of Alaska Southeast shows the glacier flowing into the water between March 31, 2016, to Aug. 8, 2016.

This work focused on one glacier, Jackson said in the statement, but it can be generalized to help researchers understand glaciers all over the world. Researchers will have to work to fit this information back into existing models, but the upshot is that the seas will rise faster than previously expected.

• Images of Melt: Earth's Vanishing Ice
• The Reality of Climate Change: 10 Myths Busted
• 5 Ways Climate Change Will Affect Your Health

Originally published on Live Science.