This year's El Niño will almost certainly become the strongest ever recorded, an analysis by a prominent climate researcher has warned. Though other scientists have cautioned that it's still too early to say what it will unleash.

Dynamical models now assign a 90% chance of the 2026-2027 El Niño being an all-time record event, sending temperatures in the Pacific Ocean up to around 3.6 degrees Celsius (6.5 degrees Fahrenheit) above average, according to an analysis by Zeke Hausfather, a research scientist at Berkeley Earth and an author of the Intergovernmental Panel on Climate Change's Seventh Assessment Report.

As the warm phase of a multiyear natural climate pattern, the El Niño could bring unprecedented temperature extremes to an already-warming world. The natural climate pattern is infamous for boosting global temperatures and fueling disruptive weather events such as floods and droughts.

A strong El Niño doesn't guarantee more severe weather impacts. The current El Niño models are also imperfect predictions of what's to come, and we won't know the true nature of this El Niño event until it peaks, likely later this year. However, forecasters have been warning of potentially supercharged El Niño conditions for months, and as more data emerges, there are more reasons to prepare.

According to projections by the World Meteorological Organization, the current El Niño — officially declared on June 11 — is on track to rapidly develop into a "strong" event between July and September. The National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center now predicts a more than 80% likelihood of very strong El Niño conditions taking hold by the end of the year, ranking this El Niño event among the largest in the historical record.

"These are striking forecasts," Emily Black, a professor of terrestrial processes and climate at the University of Reading and a senior scientist at the National Centre for Atmospheric Science in the U.K., told Live Science in an email. "El Niño forecasts always come with uncertainty, but the level of agreement between models at this time of year, combined with the observed warming already underway in the tropical Pacific, means this should be taken very seriously."

"The important point is that a very strong El Niño would substantially shift the odds of damaging weather in many parts of the world, particularly in the Global South — with severe impact on livelihoods," Black added.

The International Rescue Committee, a humanitarian organization, has warned that the intense El Niño conditions threaten to unleash severe flooding and drought across East Africa and Asia, hitting some of the most vulnerable communities, Al Jazeera reported Tuesday (July 14).

During El Niño, warmer waters gather east of the equatorial Pacific, forcing the jet stream south. In the U.S., this typically brings warmer, drier conditions to the Northeast, while the Gulf Coast and Southeast experience an increased risk of flooding. Globally, the net result of the warmer waters is more heat in the atmosphere, on top of the temperature rise from human-driven global warming.

"El Niño is a natural climate phenomenon, but it is now happening against the backdrop of a much warmer planet," Black said. "That matters because a strong El Niño releases heat and energy into an already warmed world."

"This does not mean every impact can be attributed simply to El Niño or simply to climate change," Black added. "The two interact. El Niño can load the dice towards drought in some regions, flooding in others, marine heatwaves, disrupted monsoons and unusually high global temperatures. Climate change makes many heat extremes more severe and can intensify heavy rainfall because a warmer atmosphere can hold more moisture."

The last El Niño event occurred between 2023 and 2024. Both years broke temperature records, with 2024 becoming the hottest on record and the first to breach the 1.5-degree- Celsius (2.7 degrees Fahrenheit) warming limit set by the 2016 Paris Agreement. The current El Niño is forecast to be more intense than the one in 2023 and 2024, with the projected "very strong" status putting it in a different class of severity.

The strongest El Niño in history?

Hausfather's analysis reports that there's around a 90% chance that the current El Niño will be the strongest ever recorded, with data from multimodel forecasts suggesting that it may obliterate the previous record.

"With the July runs now in from 667 ensemble members across 14 different seasonal forecast models, it looks like this year's El Niño is not only very likely to be the strongest event since reliable records began ‪—‬ it may end up the strongest by a truly mind-blowing margin," Hausfather wrote in The Climate Brink Substack post published Monday (July 13).

NOAA recognizes El Niño conditions when the eastern tropical Pacific Ocean is at least 0.5 C (0.9 F) warmer than the historical average, while wind, surface pressure and rainfall in the region are also consistent with El Niño conditions. The El Niño is then categorized as weak, moderate, strong or very strong. A very strong El Niño (above 2 C, or 3.6 F, warmer than the historical average) is often nicknamed a "super" El Niño, though it's not a scientific term.

The July models suggest that temperatures will likely sail past 2 C above average in the coming months and could potentially even exceed 3.5 C (6.3 F) above average by the end of the year. This is based on newly introduced sea surface temperature forecasts that account for rising background temperatures that can inflate El Niño warming figures. In the traditional and most widely used indices, the temperature-anomaly forecasts cluster closer to 4 C (7.2 F), with some even exceeding 4 C.

In The Climate Brink Substack, Hausfather noted that the multimodel median for the event's peak is currently forecast at 3.6 C (6.5 F), or around 0.8 C (1.4 F) hotter than the prior record holder (2.75 C, set in the 2015-2016 El Niño event). Hausfather wrote that around 91% of ensemble members (individual computer models) have this El Niño exceeding the 2015-2016 record at their peak — around 77% likelihood in the newly introduced indices.

However, Black stressed that the models are still estimates, and not guarantees.

"It is certainly plausible that this could become a record-breaking El Niño, and the latest forecasts make that a real possibility rather than a remote one," Black said. "However, I would still be cautious about treating any probability estimate as a certainty."

"There are two reasons for caution," she added. "First, this event has not peaked yet, and El Niño events usually reach their maximum strength later in the year. Second, 'strongest ever recorded' depends on the index, dataset and baseline used."

"Impacts are what matter"

The most severe El Niño events have left a trail of devastation in their wake. For example, the 2015-2016 El Niño saw a record-breaking hurricane season in the central North Pacific, severe drought in the Caribbean and Ethiopia, and, of course, abnormally hot global temperatures, according to NOAA's Climate.gov. If the forecasts pan out, the current El Niño will match or exceed the 2015-2016 event, as well as an even more infamous super El Niño that occurred between 1877 and 1878, long before modern recordkeeping of El Niño began in 1950.

The 1877-1878 event likely fueled an extreme drought that fed into the 1876-1878 global famine, which ultimately killed more than 50 million people — making it among the worst humanitarian crises in history. However, the disaster was far from just an environmental one, with extractive colonial agricultural policies helping to create conditions for a massive humanitarian crisis. Nonetheless, the famine highlights what can happen when environmental and socioeconomic factors converge.

Even though the world has changed a lot since the 19th century, experts have said a super El Niño could still cause severe shocks to our food systems. This is especially true at a time when researchers say food insecurity is not just confined to low-income countries and that climate change is already pushing agricultural systems to the brink.

The El Niño-Southern Oscillation cycle triggers a warm El Niño and then a cold La Niña roughly every two to seven years, with each phase typically lasting around nine to 12 months. Carbon Brief has predicted that 2026 is likely to be the second-warmest year on record, with the intensifying El Niño increasing the likelihood that 2027 will be the warmest year ever recorded.

The strength of an El Niño event does not necessarily correspond to the size of its influence or impact, according to the Climate Prediction Center. More severe events typically, but not always, increase the certainty of expected impacts. Black believes the impact of an El Niño event is more important than where it ranks in the observational record.

"Records are compelling, but impacts are what matter," Black said. "Even if it falls just short of a record, a very strong El Niño can still have serious consequences. Finally, these forecasts are concerning, but they are also useful: they give societies time to anticipate possible impacts and act before the worst effects are felt."

Tropical forests draw down and store large quantities of CO₂ from the atmosphere. The Amazon rainforest in South America, for example, stores approximately 123 billion tonnes of carbon — more than is stored in any other terrestrial ecosystem in the world. But these forests are facing a critical challenge.

Research from 2023, which was carried out by me and more than 100 colleagues, found that tropical forests in South America are vulnerable to climate extremes. We determined that during an El Niño event, the warm phase of a natural fluctuation in the Earth's climate system, South American tropical forests may fail to act as a carbon sink.

This finding becomes even more alarming when we consider the increasing frequency and intensity of El Niño events. There have been twice as many "very strong" El Niños in the last 60 years as there were in the 60 years before that. And the US National Oceanic and Atmospheric Administration has recently confirmed that such an El Niño is currently underway.

Tropical forests absorb CO₂ through the process of photosynthesis and convert it into biomass. However, the balance between photosynthesis and respiration is delicate and depends on two factors: temperature and water availability.

In hotter and drier conditions, plants close the pores of their leaves to avoid water loss. But closing them effectively cuts off a plant's fuel supply because it is through these pores they absorb CO₂. This starves plants of the carbon needed for photosynthesis and to grow.

During El Niño years, which are characterized by high temperature anomalies, prolonged climate stress leads to reduced forest growth and increased tree mortality. The effects of this are felt for decades as carbon is released back into the atmosphere when the dead trees decompose.

Our findings revealed that during the 2015-2016 El Niño, when temperatures on land were at least a degree higher on average than usual conditions, some of South America's tropical forests effectively stopped absorbing carbon. This raises concerns about the possible impact of the current El Niño on the Amazon and global climate.

In our research, we measured over half a million trees across six South American countries over a period of more than 30 years, using tape measures to track their growth. These trees belonged to over 4,000 different species. We used this data to calculate precise estimates of the amount of carbon stored as a forest's aboveground biomass.

We found that the vulnerability of these forests to El Niño conditions was closely linked to their baseline climate. While we tend to assume that rainforests are all hot, wet and biodiverse ecosystems, seasonal drought is a reality for many tropical forests. Conditions in regions at the edge of the Amazon rainforest, for example, tend to be particularly hot and dry.

Our findings revealed that drier forests at the edge of the Amazon, where trees regularly endure periods of limited water availability, were especially susceptible to extreme El Niño conditions. On average, a 0.5°C increase in temperature caused these forests to lose 0.5% of their aboveground carbon.

Larger trees suffered the most. While tree mortality rates increased from 1.8% to 3% per year during the El Niño in South American tropical forests as a whole, mortality rates effectively doubled for medium (classified as over 20cm in diameter) and large trees.

The fact that larger trees with less dense wood died at much higher rates compared to small trees and those with high wood density points strongly to hydraulic failure, when intense atmospheric moisture demand snaps the tension in the tree's internal water column rather than slow carbon starvation.

These results suggest that adaption to seasonal drought may not be sufficient to protect tropical forests from extreme events. Climate extremes are possibly already pushing forests at the edges of the Amazon beyond their capacity to adapt, causing catastrophic carbon losses.

A looming threat

Scientists have warned that 2026 may again be the warmest year on record. Heightening the alarm further is the severity of the current El Niño. Never before has an an El Niño begun when oceans are already so warm and air temperatures so high.

On top of this is the fact that, over the past three decades, the edges of the Amazon have experienced some of the highest temperatures and most rapid warming the tropics have ever seen. The structural integrity of a forest is compromised when a major climate anomaly occurs before it has recovered from recent, multi-year stress.

These compounding factors mean that we risk witnessing tree and carbon losses on scales not yet seen.

Tropical forests are invaluable assets in the fight against climate change. But South American tropical forests, a once-reliable carbon sink, are vulnerable to intensifying heat and drought. There is a risk these essential ecological allies stop acting as a carbon sink as extreme climate conditions become the norm.

Preserving tropical forests is thus essential. Their ability to continue acting as carbon sinks hinges on efforts to protect them and a collective commitment to limit global temperature rise. The Amazon's future depends on this, and so does ours.

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

Rainforest quiz: Can you sort Earth's largest rainforests from biggest to smallest?

June global sea surface temperatures have climbed to record highs, prompting concerns over extreme weather, flooding, sea level rise and stress to global ocean ecosystems.

The record, announced by the European Union's Copernicus Earth observation program on July 1, surpassed the previous record set in June 2024, with experts warning that more temperature records will likely be set over the coming months.

"Current conditions could indicate the beginning of a new phase, leading, once more, to uncharted territory," Carlo Buontempo, director of the Copernicus Climate Change Service at the European Centre for Medium-Range Weather Forecasts (ECMWF), said in a statement. "With ocean temperatures at these levels and El Niño on the horizon, we are likely to see more temperature records fall in the coming months.”

The record temperature was set on June 21, when the Copernicus Climate Change Service recorded global ocean surface temperatures of 20.86 degrees Celsius (69.55 degrees Fahrenheit), beating the record temperature of 20.83 C (69.49 F) set in 2023 and 2024. This measurement was corroborated by the Copernicus Marine Service, an independent dataset that reported temperatures of 21.0 C (69.8 F).

The recent sea surface heating did not occur evenly across the globe. In some areas, such as the Mediterranean, temperatures in June were up to 8 C (14.4 F) higher than average for the period from 1990 to 2020, as per data recorded on June 29, according to the European Space Agency.

The most significant rises in temperature were set in the Mediterranean, the Baltic Sea, bands across the Pacific and off the coasts of Northern Canada.

Warmer ocean temperatures have wide-ranging impacts. "Higher ocean temperatures keep the atmosphere warm for longer, provide extra energy to storms and increase evaporation, thus enhancing the potential for extreme precipitation and flooding," Copernicus Climate Change Service representatives said in the statement. "Ocean warming also contributes to sea level rise and ice melt, and stresses marine ecosystems."

According to data from the Copernicus Climate Change Service, the newly declared El Niño in the Pacific Ocean — the warm phase of a natural climate cycle. This El Niño is likely to reach levels that have not been seen in decades, with more temperature records expected to be set over the coming months as this Pacific heat is injected into an already warming world.

The service added that it remains to be seen whether these temperature spikes are temporary or indicative of longer term trends.

For half a century, scientists have known that Earth's Northern and Southern hemispheres have almost the exact same albedo ‪— the amount of sunlight they reflect back to space. This is true even though the two hemispheres look very different, with the Northern Hemisphere having more land and the Southern Hemisphere having more ocean.

Now, researchers have uncovered another surprising symmetry hiding in the data: Earth's Eastern and Western halves appear to reflect the same amount of sunlight as well, they reported in a study published June 3 in the journal Nature. They found that the dividing line lies along a great circle that wraps around the whole planet. It's made up of two longitude lines: the 27 degrees east and 153 degrees west meridians, which stretch from the North to South Pole through Eastern Europe, Turkey, Central Africa, Norway and Alaska.

"Given that the Earth is approximately spherical, it is unsurprising that one can divide it into two non-overlapping hemispheres that reflect equal amounts of sunlight," the authors write in the paper. But what is surprising, they write, is how closely matched they are. The probability of the hemispheres naturally reflecting sunlight within 0.01 watts per square meter of each other is less than 3%.

If the symmetry is a fundamental part of Earth’s climate, this finding could help scientists test and possibly improve global climate models to predict future warming.

Secret symmetry

While the exact mechanism for the northern and southern symmetry has evaded scientists for decades, the study authors said they may have identified a reason behind their discovery.

Since the dawn of the space race in the late 1950s, scientists have wanted to figure out Earth's albedo. "That was a really burning question back then," Norman Loeb, an atmospheric scientist who leads NASA's Clouds and the Earth's Radiant Energy System (CERES) project who wasn't involved in the new study, told Live Science. And around a half century ago, they figured it out with satellite imagery.

Earth's planetary albedo is about 29%, according to the study. This means that about 0.29 of the solar radiation that hits Earth is reflected back into space. In contrast, a perfect mirror would have an albedo of 1, as it would reflect back 100% of the light that hit it.

Other analyses showed that the Northern Hemisphere's albedo was the same as the Southern Hemisphere's, although recent research co-authored by Loeb suggests that the Northern Hemisphere is now absorbing more light than the Southern, likely because of melting snow and ice, declining air pollution, and rising water vapor.

This newfound imbalance aside, Zhang, a researcher at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, and colleagues wondered if other symmetry pairs had been overlooked or if they were considered too trivial to investigate, Zhang wrote in a blog.

To identify the symmetry, Zhang and his colleagues analyzed 25 years of satellite observations from 2001 to 2025 collected by the CERES program, which uses satellites to measure Earth’s energy budget. Instruments on these satellites measure how much reflected sunlight bounces back into space, as well as how much heat is emitted from Earth

Earth's albedo is shaped by many factors; clouds, oceans, snow, ice and land each reflect a different amount of sunlight. This reflection influences Earth's climate, so understanding it is key to an accurate understanding of climate in the future.

After running the first analysis, Zhang wrote he was both "absolutely amazed" and skeptical at what he saw, but three features stood out.

First the symmetry is unique to the meridian at 27 east longitude. If you shift the line to any other longitude, the symmetry disappears. Second, it's consistent across a 25-year dataset. Lastly, there is "triple symmetry": The two hemispheres contain similar proportions of ice-free ocean, experience similar cloud effects, and reflect similar amounts of sunlight under clear skies.

El Niño connection

Zhang and his authors hypothesize the East-West symmetry is tied to the El Niño-Southern Oscillation (ENSO), a recurring climate pattern that shifts ocean temperatures and weather around the globe. When they examined the slight changes in the exact longitude of this symmetry, they found correlation with the ENSO record.

In the tropics, a giant loop of air called the Walker circulation acts like a big conveyor belt. Warm, moist air rises in the West, travels eastward high in the atmosphere, and then cools and sinks, before blowing back westward at the surface. This circulation acts as the albedo adjustment mechanism, according to the study.

The Walker circulation helps drive the difference between El Niño and La Niña, recurring climate patterns, based on weaker or stronger Pacific trade winds, respectively.

During La Niña years, the circulation is stronger, causing warmer water and so the Eastern Hemisphere has more clouds, and thus reflects slightly more sunlight. During El Niño, the circulation weakens, warm water spreads across the Pacific and so the Western Hemisphere reflects more. Over many years, the swings average out, helping to keep the long-term east-west symmetry centered near 27 degrees east.

"Nature throws surprises at us, so this is a curious surprise that this one longitude seems to divide the globe up very symmetrically," Loeb said. "It's really interesting that there's this single point longitude at 27 degrees."

Since the models are designed to simulate Earth's interactions among the atmosphere, oceans, lands, crust and other parts, the new symmetry offers another way to test if current climate models are accurate. "I think the short-term benefit of this type of discovery is that it's a further test of climate models," Loeb noted.

But when the scientists tested how the current models predicted new symmetry, "the models didn't do very well," Loeb said. "They didn't produce this East-West symmetry." This problem may be "contributing to the persistent uncertainty in climate projections," according to the study.

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A massive wave of warm water is making its way across the Pacific Ocean as the newly declared El Niño gets into full swing, satellite images show.

The band, called a Kelvin wave, marks a swell of higher-than-average sea levels that stretches hundreds of miles along the equator. The anomaly is caused by warmer waters linked to El Niño — the warm phase of a natural climate pattern whose current iteration could become one of the strongest ever recorded.

The Sentinel-6 Michael Freilich satellite captured the deviations from average sea surface height on June 8. Red areas indicate higher sea surfaces than usual, while blue areas mark areas with lower surface heights.

Developed and launched in 2020 by NASA and the European Space Agency and operated by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), Sentinel-6 Michael Freilich measures changes in sea surface height down to fractions of an inch every 10 days.

The data complements measurements of sea surface temperature that have shown Pacific waters warming at unpreceded rates over the past several months, leading scientists to declare the start of a new El Niño on June 11. When ocean water warms, it expands and takes up more space. That translates to an increase in the height of the water relative to the satellite and the center of Earth, which is then picked up by the satellite's sensitive equipment. At some points along the equator, sea surfaces are now more than 6 inches (15 centimeters) higher than usual.

Kelvin waves like this one form when winds in the western Pacific near the equator weaken and temporarily reverse, blowing from west to east instead of east to west. That lets warm water gradually build up in the east, deepening the layer of warm surface waters and preventing colder waters from rising from below. The wave has now reached the western coast of South America.

NASA had already observed a few other Kelvin waves this year, suggesting an El Niño event was soon to follow. In January, Sentinel-6 Michael Freilich detected one near Micronesia that dissipated around mid-February. Another emerged in March and elevated sea levels near Peru by mid-May.

Changes in sea surface temperature or height can alter atmospheric circulation patterns and affect the weather. El Niño often increases rainfall in the southwestern U.S., Colombia, Peru and Ecuador, while rainfall in the western Pacific tends to decrease. The most recent El Niño, which lasted from June 2023 to April 2024, boosted global mean temperatures that made 2024 the hottest year on record and the first to breach the 1.5 degrees Celsius (2.7 degrees Fahrenheit) warming limit — a guardrail set by the Paris Agreement beyond which the effects of climate change become more and more catastrophic.

The June 8 conditions in the western Pacific were similar to those that occurred 1997 during a particularly strong El Niño, according to a statement from NASA. 2026 has seen fewer Kelvin waves so far than 1997, but this year’s El Niño is still ramping up.

"For now, it looks like it's going to be a big one — more so than I would have said last week — but we still need more observations to know what's going to happen," Severine Fournier, a sea level researcher at NASA’s Jet Propulsion Lab, said in the statement.

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It's official: El Niño is here, and it's shaping up to be among the strongest ever recorded.

The natural climate cycle, which supercharges temperatures and shifts weather patterns across the planet, officially took hold over the past month, according to a June 11 update by the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center.

What's more, an accompanying average of various forecasting models gives a "63% chance of a very strong El Niño during November-January that would rank among the largest El Niño events in the historical record going back to 1950," NOAA officials wrote in the update.

This is no longer much of a surprise. Last week, the European Centre for Medium-Range Weather Forecasts, considered the "gold standard" of global weather models, suggested that this year's brewing El Niño would likely become the strongest ever recorded.

That prediction is increasingly shared by the world's best climate models, with about 75% of them now forecasting a record-breaking surge of at least 4.5 degrees Fahrenheit (2.5 degrees Celsius) above average sea surface temperatures across key parts of the Pacific Ocean, according to Europe's Copernicus Climate Change Service, with other model scenarios climbing as high as 7.2 F (4 C).

For reference, the past two strongest recorded El Niño events (2015-2016 and 1997-1998) sent ocean temperatures to 4.1 F (2.3 C) above average in the Niño 3.4 index, which measures sea surface temperatures across a key region of the Pacific Ocean.

What is El Niño?

El Niño events occur every two to seven years as part of the El Niño-Southern Oscillation (ENSO) natural climate cycle in the Pacific Ocean. The ENSO cycle flips between the warmer El Niño phase and the cooler La Niña phase, with neutral periods in between. El Niño periods bring elevated sea surface temperatures in the central and eastern Pacific, thereby weakening or reversing trade winds and strongly disrupting global temperatures and rainfall patterns.

Earth's last El Niño ran from June 2023 to April 2024, delivering an injection of heat to our already-warming world that made 2024 the hottest year on record. That year was also the first to breach the 1.5 C (2.7 F) warming limit — a key guardrail set by the Paris Agreement, beyond which the effects of climate change are predicted to become increasingly disastrous.

The current El Niño will also raise global temperatures this year and next, making it likely that Earth will reach, or even surpass, those previous records.

Now that El Niño's onset is official, scientists can advise people around the world on how to prepare. The impacts of this extra burst of heat stand to be profound, with studies linking previous El Niño periods to famine in Europe; civil wars in tropical regions; and droughts, floods and forest fires around the world. This year's El Niño will arrive during a period of already-increased global food insecurity driven by the Iran war.

And while El Niño would have occurred regardless, scientists are seeing signs that this El Niño's quicker-than-expected onset was driven by humanity's warming of the planet.

"It might be one of the most rapid transitions that I've seen in the record ‪—‬ maybe the most rapid," Nathaniel Johnson, a research meteorologist and member of the ENSO seasonal forecast team at NOAA, told Live Science in a May 1 interview. "Because, to go from a weak-to-moderate La Niña to a strong-to-very-strong El Niño within one calendar year is just not something we see very often."

"Over the past century, we have seen an increase in these more rapid swings from one state to the other," he added. "So there's some suggestion that potentially climate change could play a role in making these swings more rapid between El Niño and La Niña. It's something that will take more investigation."

This year's brewing El Niño will likely become the strongest ever recorded, a new forecast warns.

New predictions by the European Centre for Medium-Range Weather Forecasts (ECMWF) suggest sea surface temperatures in a key region of the central equatorial Pacific Ocean will climb 5.4 degrees Fahrenheit (3 degrees Celsius) above average by December of this year, with some scenarios showing they could go above 7.2 F (4 C).

If the forecast bears out, it means that this year's El Niño — the warm phase of a multi-year natural climate pattern that supercharges temperatures across the globe — will be significantly stronger than the previous joint record holders of 2015 to 2016 and 1997 to 1998.

Those past two El Niño events sent temperatures in the Niño 3.4 index (which measures sea surface temperature anomalies between 5 degrees north and 5 degrees south latitude, and 120 degrees west and 170 degrees west longitude) to 4.1 F (2.3 C) above average.

"Almost every scenario now reaches past +3˚C, with a cluster of high-end scenarios in excess of +4˚C," Ben Noll, a meteorologist and global weather writer at the Washington Post, wrote on the social platform X. "This outlook now depicts the strongest El Niño on record."

El Niño events occur every two to seven years as part of the El Niño-Southern Oscillation (ENSO) natural climate cycle in the Pacific Ocean. The ENSO cycle flips between the warmer El Niño phase and the cooler La Niña phase, with neutral periods in between. El Niño periods bring elevated sea surface temperatures in the central and eastern Pacific, thereby weakening or reversing trade winds and strongly disrupting global temperatures and rainfall patterns.

Earth's last El Niño ran from June 2023 to April 2024, delivering an injection of heat to our already warming world that made 2024 the hottest year on record and the first to breach the 1.5 C (2.7 F) warming limit — a key guardrail set by the Paris Agreement, after which the effects of climate change become increasingly disastrous.

The impacts of previous El Niño periods on global agriculture have been profound, with studies linking the events to famine in Europe; triggers for civil wars in tropical regions; and droughts, floods and forest fires around the world. This year's El Niño will arrive during a period of increased global food insecurity driven by the Iran war.

In an update on Tuesday (June 2), the World Meteorological Organization (WMO) warned that the climate pattern has an 80% chance of forming before September and a 90% chance before November, and that the world should prepare for a potentially strong event.

"The science is clear: El Niño is arriving on our doorstep in the coming months with 90% certainty. The world must treat it as the urgent climate warning it is," UN Secretary-General António Guterres said in a video statement.

And while El Niño would have arrived regardless of anthropogenic climate change, Guterres was careful to stress that it will add more heat to an already dangerously warming planet.

"El Niño conditions will pour fuel on the fire of a warming world. Impacts will hit even harder, travel even farther, and cross borders with devastating speed," he added.

"The only effective response is climate action equal to the crisis — ending the addiction to fossil fuels, accelerating the shift to renewables, protecting the most vulnerable, and delivering early warning systems for all."

A "super" El Niño is now the most likely scenario from October 2026 to February 2027, according to a new forecast from the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center.

El Niño is the warmer phase of the natural El Niño-Southern Oscillation (ENSO) climate cycle, a periodic shift in the waters of the tropical Pacific Ocean that supercharges global temperatures, in turn impacting weather patterns and crops worldwide.

Now, in a new ENSO forecast published May 14, NOAA estimates that there's a 65% chance that the upcoming El Niño will be classified as strong or very strong starting in October, potentially placing it among the strongest in recorded history.

A "very strong" El Niño — meaning a 3.6-degree-Fahrenheit (2 degrees Celsius) rise in sea surface temperatures, and unofficially called a "super" El Niño — is now the most probable scenario for the October-to-February period.

There is also now an 82% chance that El Niño will arrive between now and July, with the phase looking highly likely to continue until February 2027. This is a roughly 20 percentage-point increase in certainty from NOAA's April forecast that El Niño is right around the corner.

A "very strong" El Niño could wreak havoc

El Niño events occur every two to seven years, when shifts in wind and current patterns in the tropical Pacific Ocean cause sea surface temperatures to rise 0.9 F (0.5 C) above historical averages, resulting in profound knock-on effects on the global climate. The world is rapidly exiting the neutral phase.

The world's most recent El Niño spanned from May 2023 to March 2024 and was partially responsible for 2024 being the hottest year on record. If the upcoming El Niño is strong or very strong, 2027 could surpass the previous record, according to Climate Brief's State of the Climate assessment, published April 21.

In fact, the impending El Niño may itself break records. "Confidence is clearly shifting higher on potentially the biggest El Niño event since the 1870s," Paul Roundy, a professor of atmospheric and environmental sciences at the University at Albany, wrote on X on May 5.

If a "super" El Niño does occur, it could rival the strongest on record: a catastrophic 1877 event that spurred the 1876-to-1878 global famine. The famine killed over 50 million people, or 3% of the world's population at the time.

Although the social, political and economic landscapes have changed since the 1877-to-1878 El Niño, the upcoming event could still seriously threaten food, water and economic security around the world, Deepti Singh, head of the Climate Extremes and Impacts Lab at Washington State University, told The Washington Post.

"What is different now is that our atmosphere and oceans are substantially warmer than they were in the 1870s, which means the associated extremes could be more extreme," Singh said.

More recent examples demonstrate the threat of strong and very strong El Niño phases. For example, an El Niño in 1997 to 1998 led to an estimated global economic loss of $32 billion to $96 billion.

NOAA ENSO forecaster Nathaniel Johnson recently told Live Science that a very strong El Niño would impact fisheries and crops, as well as heighten the risk of wildfires and hurricanes in parts of the world.

"You've got more people that are living in poverty already and if you get a reduction in crop yields because of drought or flooding [from El Niño] then that drives prices even higher," Liz Stephens, a professor of climate risk and resilience at the University of Reading in the U.K., told the BBC. "So we're looking at potentially quite huge humanitarian impacts this year, especially if the crisis in the Middle East continues."

The next NOAA ENSO forecast will arrive June 11.

Ocean temperatures reached a near-record-breaking monthly high in April as forecasters warn that we could be on the cusp of one of the strongest El Niño events of the century.

El Niño is the warm phase of a multi-year natural climate pattern that increases global temperatures. Forecasters have predicted that there's a one in four chance that an unusually strong, or "super" El Niño, could emerge this year, with new data suggesting that warming El Niño conditions will soon be upon us.

The European Union's Copernicus Climate Change Service has found that sea surface temperatures in April reflected a transition to El Niño conditions. Across the extrapolar global ocean, which encompasses all oceans except for the icy Arctic and Antarctic regions, surface temperatures were the second highest for any April on record (21 degrees Celsius, or 69.8 degrees Fahrenheit), trailing only those seen in April 2024 (21.04 C, or 69.87 F) — the warmest April ever recorded.

Earth's last El Niño ran from June 2023 to April 2024, delivering an injection of extra heat to our already warming world. Both years saw temperature records tumble, with 2024 ending up the hottest on record and the first to breach the 1.5 C (2.7 F) warming limit, a key guardrail set by the Paris Agreement before which the effects of climate change become increasingly disastrous. Notably, the 2023/2024 El Niño was on the cusp of the "super" threshold.

El Niño is marked by atmospheric and sea temperature changes in the tropical Pacific Ocean. Of course, Earth and its oceans are heating up anyway due to human-caused global warming, so the spike in sea surface temperatures last month is about more than natural climate patterns.

"April 2026 adds to the clear signal of sustained global warmth," Samantha Burgess, the strategic lead for climate at the Copernicus Climate Change Service, said in a statement. "Sea surface temperatures were near record levels with widespread marine heatwaves, Arctic sea ice remained well below average, and Europe saw sharp contrasts in temperature and rainfall; all hallmarks of a climate increasingly shaped by extremes."

The El Niño-Southern Oscillation cycle (ENSO) triggers a warm El Niño and then a cold La Niña around every two to seven years. Each phase tends to last around nine to 12 months, but the timing of their emergence and duration varies.

The National Oceanic and Atmospheric Administration (NOAA) recognizes El Niño conditions when the eastern tropical Pacific Ocean is 0.5 C (0.9 F) or more warmer than the historical average, while wind, surface pressure and rainfall in the region are also consistent with El Niño conditions.

Last month, NOAA's Climate Prediction Center announced that there is a 61% chance of El Niño emerging between May and July, which would then very likely persist through the rest of 2026. The center also gave a one in four (25%) chance of a very strong El Niño (above 2 C, or 3.6 F) emerging during the upcoming Northern Hemisphere winter, which is when El Niño conditions typically peak.

NOAA is unusually confident in its El Niño forecast for this time of year, which tends to be less accurate in spring due to the season's chaotic weather. However, the tropical Pacific Ocean appears to be rapidly moving away from La Niña conditions (0.5 C below the historic average), which occurred between September and January, through neutral conditions, and towards a potentially strong El Niño.

"If this does turn out to be a very strong El Niño, it might be one of the most rapid transitions that I've seen in the record ‪—‬ maybe the most rapid," Nathaniel Johnson, a research meteorologist and member of the ENSO seasonal forecast team at the Climate Prediction Center, told Live Science in an interview published May 1.

The cause of this year's potentially supercharged El Niño will be explored after the fact. However, Johnson noted that there's some suggestion that climate change could potentially be playing a role in making El Niño and La Niña swings more rapid, though this has yet to be confirmed.

"Super El Niño"

Many meteorological organizations don't recognize the term "super El Niño," but it's an informal way of saying "very strong El Niño." Potential impacts of such an event include a decline in fisheries, as well as droughts, wildfires and coral bleaching.

The Climate Prediction Center is one of several groups predicting El Niño and the potential for supercharged conditions. The U.K.'s Met Office is another, and has said that confidence is growing in projections that this upcoming event could be at the upper end of the historical range.

"A 'super' El Niño is not a term we subscribe to, but it does underpin the fact that this is likely to be a significant event," Grahame Madge, a senior press officer and climate science communicator at the U.K. Met Office, said in a statement released April 15. "Scientists are telling us that this could be the strongest El Niño event this so far century, comparable to the notable El Niño event in 1998."

The 1998 event, which began in 1997 and lasted for 13 of the NOAA's overlapping three-month sea surface temperature averaging periods (between May 1997 and June 1998), saw temperatures rise up to 2.4 C (4.3 F) above the historical average, according to NOAA data. The only very strong El Niño to occur this century was of a similar magnitude. Between 2015 and 2016, El Niño conditions lasted for 20 overlapping three-month periods, and peaked at 2.8 C (5.04 F) above the historical average, according to NOAA. However, the 2015/2016 event was weaker than the 1997/1998 event in the eastern Pacific.

El Niño typically increases global temperatures by about a fifth of a degree Celsius, according to Madge. This is a temporary rise on top of global warming, which, regardless of its influence on the ENSO cycle, is the reason our planet is warming.

Will 2026 be the warmest year on record?

Carbon Brief has predicted that 2026 is likely to be the second-warmest year on record, while a strong El Niño developing later this year increases the likelihood that 2027 will be the warmest year ever recorded.

World leaders previously agreed to limit warming to preferably below 1.5 C and well below 3.6 F (2 C) in the 2015 Paris Agreement, a legally binding international treaty. The Paris Agreement is for temperature anomalies averaged over at least 20 years, so while 2024 was warmer than 1.5 C, the limit hasn't technically been breached yet, though the United Nations Environment Programme expects warming to speed past the 1.5 C climate threshold in the next decade.

Our warming world is set to enter an El Niño period as early as May, with a high likelihood of southern North America experiencing supercharged temperatures.

One of the three phases of the natural El Niño-Southern Oscillation (ENSO) cycle in the Pacific Ocean, El Niño events occur every two to seven years, driving up sea surface temperatures across the Pacific Ocean and increasing global temperature. The last El Niño partially explains why 2024 was the hottest year on record.

The knock-on effects of past El Niño events have been profound, with studies linking them to famine in Europe; civil wars in tropical regions; and droughts, floods and forest fires around the world.

And there's a good chance this year's El Niño will be particularly intense, with current forecasts indicating a 25% chance that El Niño will be "very strong" by November ‪—‬ meaning sea surface temperatures will rise by 3.6 degrees Fahrenheit (2 degrees Celsius) above average.

To get a better idea of what the upcoming El Niño will look like and what it could mean for Earth's climate and weather, Live Science spoke with Nathaniel Johnson, a research meteorologist and member of the ENSO seasonal forecast team at the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center. Here's what he had to say.

Sophie Berdugo: How does NOAA predict and classify El Niño?

Nathaniel Johnson: Our basic classification of El Niño is based on the relative sea surface temperatures in this Eastern Central equatorial Pacific. And by relative, it means relative to the tropical average.

So, when the East Central tropical Pacific sea surface temperatures are more than 0.5 C [0.9 degrees Fahrenheit] above the tropical average, then we have El Niño conditions.

We can further subdivide El Niño into weak, moderate and strong. So that's more of an unofficial subdivision just based on how warm the ocean surface is in the east central tropical Pacific.

SB: What are the thresholds for those unofficial subdivisions, and how rare is each category?

NJ: El Niño is declared when the Relative Oceanic Niño Index — that's a measure of the ocean temperatures in the east central tropical Pacific box — is more than 0.5 C above the tropical average.

So between 0.5 C and 1 C [1.8 F], that would be a weak El Niño. El Niño, on average, occurs about every three to four years. Many times, it's a weak El Niño. If this index is between 1 C and 1.5 C [2.7°F], then we say it's a moderate event.

If it's 1.5 C to 2 C, we consider it a strong event. And then above 2 C is a very strong event. A very strong event is the sort of event that happens maybe once every 10 to 20 years.

What is the current forecast for the upcoming El Niño, and how certain is it?

NJ: Currently, NOAA predicts about a 90% chance that El Niño will develop by this fall. Usually, it's more difficult to make a forecast for El Niño in the spring: we have a so-called spring predictability barrier where forecasts tend to be less confident in the spring. So the fact that NOAA predicts a 90% chance is unusual for this time of year.

And there's about a 50% chance that it will at least be a strong event ‪—‬ (so, again, that index above 1.5°C ‪—‬ and about a 25% chance that'll be a very strong event, so above that 2°C.

There's still a lot of uncertainty about how strong this event will be. But I'd say it's still unusually confident that we will have an El Niño given that, this time of year, it's often difficult to be very precise about our El Niño forecast.

SB: Why is it tricky to forecast this time of year? And what does the fact that we've already got quite a high certainty that it's coming mean for this impending El Niño?

NJ: El Niño requires cooperation between the atmosphere and the ocean, so there has to be certain feedbacks between the tropical atmosphere and ocean. And coupling between the ocean and atmosphere is weaker this time of year, just because of seasonal changes in the average sea surface temperature.

So, for example, there's less of an east-west contrast between the Western Pacific and the Eastern Pacific. And that contrast between the East and West is what's important for this coupling between the tropical atmosphere and ocean.

So what that means is that it's easier to disrupt the development of an El Niño by just chaotic weather. So things that we cannot predict more than a few weeks in advance, for example, if we suddenly had strong winds coming from the East to West, that could help disrupt an El Niño.

The fact that we're this confident that El Niño will develop just tells us that, despite these uncertainties, despite the compounding impacts of the chaotic weather, the conditions are really well aligned for this El Niño to develop. We haven't seen anything, any signs that this progression is being disrupted. Everything so far seems to be aligning with this rapid change from the La Niña conditions we had last boreal winter [winter in the Northern Hemisphere]. We're now neutral, but the Eastern Pacific is warming up pretty quickly right now.

SB: Is it unusual how rapidly we've got this new El Niño approaching?

NJ: Yes, it is actually pretty unusual. The other way around is not so unusual. It's actually pretty common to go from, say we have a strong El Niño, to rapidly transition to a La Niña. But the other way around, going from a weak to almost moderate La Niña into El Niño and potentially a strong El Niño, that is more rare.

And, in fact, if this does turn out to be a very strong El Niño, it might be one of the most rapid transitions that I've seen in the record ‪—‬ maybe the most rapid. Because, to go from a weak-to-moderate La Niña to a strong-to-very-strong El Niño within one calendar year is just not something we see very often.

SB: So what could be causing that?

NJ: It's something that's going to have to be diagnosed after the event if it does turn out that way.

I'll just note that over the past century, we have seen an increase in these more rapid swings from one state to the other. So there's some suggestion that potentially climate change could play a role in making these swings more rapid between El Niño and La Niña. It's something that will take more investigation.

SB: What impact could a very strong El Niño event have on climate and food systems this year?

NJ: If we did have a very strong El Niño, it would have, for example, impacts on our fisheries. If we had a very strong El Niño, we could have a collapse of the Eastern equatorial Pacific "cold tongue," so that would reduce the amount of nutrient-rich water that gets upwelled. [Editor's note: The Eastern equatorial Pacific "cold tongue" is a nutrient-rich body of surface water in the Pacific Ocean.]

That would have potentially a very significant negative impact on, say, anchovy fisheries in Peru. We tend to see a migration of warm-water fish to warmer waters, like tropical fish migrating northward or to the West Coast of North America. Maybe cold-water species may see a decline of fish like salmon.

We see, potentially, negative impacts on crops where there's drought, so places like from Indonesia to Australia to northern South America tend to have drought. Those are some of the big impacts on food.

The wildfire risk would be increased over places including Australia, Indonesia, northern Brazil, parts of maybe western Canada and northern U.S., where the conditions are expected to be drier.

A very strong event just generally means much warmer tropical waters in general. So, coral bleaching could potentially be quite severe. So it's a lot of potentially strong ecological impacts from a very strong event.

SB: The most recent El Niño lasted from 2023 to 2024, and 2024 became the hottest year on record. What can we expect in terms of global temperatures for this upcoming El Niño?

NJ: El Niños tend to bring a temporary spike in the global mean temperature. If it turns out to be a strong event, then that would tend to be an even bigger spike on top of the long-term warming trends. So, if we were to have a stronger El Niño, then it would just increase the likelihood that we could have a new record in global mean temperatures.

SB: What will the impacts be on the U.S., parts of which are already facing severe drought conditions even before summer?

NJ: The impacts on the U.S. would tend to be strongest in our winter, although beforehand, the first notable impact would be on the hurricane season. Typically, during El Niño, we see a suppression of the Atlantic hurricane season and an enhancement of the Eastern Pacific season — so overall, maybe a reduced risk of tropical cyclones in the summer and fall.

But then, typically in the winter, we see enhanced rainfall and snowfall over the Southern tier of the U.S. So that would be potentially good news for the drought-stricken regions of the Southern part of the U.S.

But that shift to the storm track south would mean that drought in the more Northern areas may persist. So it would enhance the probability of persisting drought over the Northern parts that have been affected.

SB: So could El Niño bringing heightened winter rainfall to drought-stricken Southern parts of the U.S. lead to a greater risk of flooding?

NJ: Drought relief obviously would be great, but there is a potential heightened risk of floods. Particularly if we have a strong to very strong event, what we see is that the subtropical jet stream gets extended more to the East, more towards the North American continent. That could lead to more frequent, say, atmospheric rivers over parts of the West Coast — places like California.

And those atmospheric rivers, of course, bring beneficial rain and snowfall ‪—‬ you know, snowpack to the Midwest‪ —‬ but they also bring flooding and destruction from winds. And so there's always both positives and negatives that they can potentially counterbalance each other.

SB: What should people and governments do to prepare?

NJ: I think, at this point, they [should] just prepare for the enhanced risks that are associated with an El Niño of various strengths ‪—‬ understanding that there's still uncertainty in terms of the amplitude, as I mentioned, but there is a potential for a strong to very strong event. All these risks that are associated with El Niño, just be prepared to devote the resources necessary to address those risks.

Again, it's not certain — there's always other factors — but the stronger the event, the more likely it is that this El Niño is going to dominate over the other factors that could be influencing our weather and climate.

SB: There's been a lot of talk about there being a "super" El Niño and what the potential impacts will be. What is your closing message to readers?

NJ: I guess my message would be to try to filter out the hype and just focus on the solid science. Have a rational viewpoint of the forecast, which is, an El Niño is likely; there's still uncertainty in terms of how strong it will be. Just be aware of the potential impacts that may come, and note that we're going to continue to fine-tune the forecast in the months ahead.

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

El Niño is forecast to return as early as May, which could bring above-normal temperatures to almost everywhere on Earth, according to a new report.

El Niño events occur every two to seven years as part of the El Niño-Southern Oscillation (ENSO) natural climate cycle in the Pacific Ocean. The ENSO cycle flips between the warmer El Niño phase and the cooler La Niña phase, with neutral periods in between. El Niño periods bring elevated sea surface temperatures in the central and eastern Pacific, thereby weakening or reversing trade winds and strongly disrupting global temperatures and rainfall patterns.

In a Global Seasonal Climate Update published April 21, the World Meteorological Organization (WMO) reported that El Niño is set to develop during the May to July season. Although the confidence of the prediction will improve after April, models currently suggest this El Niño could be a "strong event," according to the WMO.

"After a period of neutral conditions at the start of the year, climate models are now strongly aligned, and there is high confidence in the onset of El Niño, followed by further intensification in the months that follow," said Wilfran Moufouma Okia, chief of climate prediction at the WMO.

The impacts of El Niño periods on global agriculture are profound, with studies linking the events to famine in Europe; civil wars in tropical regions; and droughts, floods and forest fires around the world.

The most recent El Niño period lasted from May 2023 to March 2024 and contributed to 2024 being the hottest year on record.

Now, the Global Seasonal Climate Update predicts a "rapid warming trend" for May, June and July. Elevated temperatures are highly likely in southern North America, Central America, the Caribbean, Europe and Northern Africa.

Rainfall patterns will shift greatly across the world. Some parts of North America could get wetter, but the lack of a clear signal means it's currently unknown.

In March, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center announced that there was a 62% chance of El Niño emerging between June and August. NOAA has since said there's a 61% of El Niño returning in May to July and continuing through the rest of the year. The WMO does not use the term "super El Niño," but NOAA predicts a 25% chance of a "very strong" El Niño beginning in November.

The WMO will publish a revised El Niño update in late May.

Today's top story

Super El Niño cometh

A "super El Niño" is on the cards this summer, and it could supercharge temperatures to make 2027 a contender for the hottest year on record.

That's according to the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center, which declared there is a 62% chance the natural climate pattern will emerge between June and August, and a 1-in-3 likelihood it will be especially strong.

That's big news for our increasingly disrupted climate, with El Niño tending to strengthen hurricane activity over the central and eastern Pacific while suppressing hurricanes in the Atlantic, and triggering extreme weather such as floods, droughts and heatwaves across the globe.

The trend

Crowded skies

There are now 10,000 Starlink satellites above our heads. The news comes as a Falcon 9 rocket, which launched from California last night, added 25 new satellites to the growing low Earth orbit constellation. [Spaceflight Now]

It's a remarkable technical achievement, especially considering the tens of thousands of avoidance maneuvers satellites in the array need to complete to avoid crashing into each other. But it also comes at a great cost to radio astronomy and potentially to nearby spacecraft, while also raising the odds of an uncontrolled orbital chain reaction.

Three to read

1. U.K. officials race to contain the spread of a bacterial strain of meningitis behind a fatal outbreak in Kent, England. [The Guardian]
2. Federal court blocks Health and Human Services (HHS) Secretary Robert F. Kennedy Jr.’s vaccine changes, alongside his remaking of a key vaccine advisory panel. [The Hill]
3. A single injection of mRNA-like treatment could help heart muscle heal after a heart attack in mice and pigs. Could it work in humans too? [Live Science]

Say it, said it

Word of the day: Etosha — An Oshindonga (dialect of Namibian) word that translates roughly to "Great White Place." The Etosha Pan is an approximately 1,800-square-mile (4,700 square kilometers) salt flat north of Namibia's capital, Windhoek. And it looks absolutely stunning from space.

Quote of the day: "Think of your brain like a city: while the whole city is awake and active, a few specific 'neighborhoods' (brain regions) decide to turn off their lights for a second. If those neighborhoods are responsible for attention, you experience a lapse."

Elaine Pinggal, a neuroscientist at Monash University, Melbourne, on how sleep-like brain activity can make our attentions lapse, and how adults with ADHD experience them much more often.

Fun and games

This crossword by Senior Staff Writer Harry Baker took our Editor-in-Chief Alexander McNamara one minute and 55 seconds to complete. Think you can beat him?

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Forecasters predict that a potentially supercharged El Niño is coming this summer, and it could push temperatures across the globe to unprecedented extremes.

Last week, the National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center announced that there is a 62% chance of El Niño emerging between June and August. In other words, El Niño is more likely than not this year.

El Niño is the warm phase of the El Niño-Southern Oscillation (ENSO), a natural climate pattern of atmospheric and sea temperature changes in the tropical Pacific Ocean. During El Niño, warmer waters gather east of the equatorial Pacific, forcing the jet stream south. This brings warmer and drier conditions to the northern U.S., while the Gulf Coast and southeastern U.S. have an increased risk of flooding.

The tropical Pacific Ocean is currently in the midst of La Niña, the cold phase of ENSO, when sea surface temperatures fall at least 0.9 degrees Fahrenheit (0.5 degrees Celsius) below the long-term average. La Niña is expected to end in the coming weeks as the sea warms, according to the latest Climate Prediction Center announcement. El Niño will then occur if sea surface temperatures reach and remain at least 0.9 F above the long-term average.

If El Niño does emerge as anticipated, it could intensify into a "super El Niño," AccuWeather reported. A super El Niño occurs when sea surface temperatures reach at least 3.6 F (2 C) above the long-term average.

"Intensity is uncertain but there is potential for a moderate to possibly strong El Niño this fall into winter," Paul Pastelok, a meteorologist and lead U.S. long-range forecaster at AccuWeather, said, per the weather website.

Accuweather's forecasters estimate that there's a 15% chance of a super El Niño developing by the end of the hurricane season in November. Meanwhile, NOAA's Climate Prediction Center gives a 1-in-3 chance of a strong El Niño emerging between October and December but describes the potential strength as "very uncertain."

El Niño tends to strengthen hurricane activity over the central and eastern Pacific while suppressing hurricanes in the Atlantic, which typically leads to a less-active hurricane season overall.

The ENSO cycle triggers a warm El Niño and then a cold La Niña every two to seven years, on average. However, they aren't always on time. Equally, while each phase tends to last around nine to 12 months, their duration varies.

Earth was last in El Niño between May 2023 and March 2024. On that occasion, El Niño was close to being a super El Niño, but while sea surface temperatures breached the 3.6 F threshold, they didn't remain above the threshold for long enough to qualify. The last super El Niño occurred in 2015-2016.

The last El Niño contributed to record-breaking heat in 2023 and 2024, with 2024 currently the hottest year on record. If El Niño emerges in 2026, then the year will get warmer, but is unlikely to be as hot as 2024 — we started the year in La Niña, after all. Global temperatures in 2027, however, could be pushed to record-breaking heights, according to a post on the social media platform X by Zeke Hausfather, a climate scientist and energy systems analyst.

"The El Nino cometh," Hausfather wrote. "This would push up our estimate for 2026 global temperatures (though its still unlikely to surpass 2024 as the warmest year), and make 2027 very likely to be the warmest year on record given the historical lag b/w ENSO and surface temp."

It's important to remember that a variety of factors influence the weather and climate. The planet is already warming due to climate change and will continue to do so, regardless of what ENSO is doing.

Scientists have identified a tipping point that has amplified El Niño’s effect on sea ice loss in the Arctic.

For years, researchers have known of a feedback loop linking the El Niño-Southern Oscillation (ENSO) and sea ice coverage at high latitudes. But in a new study, researchers found that since around the year 2000, faster transitions between phases of ENSO have a stronger influence on ice loss northeast of Russia. These changes lead to warmer, wetter weather in the region and less sea ice coverage during the fall following the transition.

The results of the new study could help improve predictions of sea ice coverage for ships passing through the region. They could also help scientists better understand the effects of long-term fluctuations in Earth's climate. "Sea ice can make a significant impact on the Arctic climate and maritime safety," study co-author Cen Wang, an atmospheric scientist at The Hong Kong University of Science and Technology, told Live Science.

ENSO is a climate phenomenon involving variations in air pressure and sea surface temperatures in the tropical Pacific over multiple years. These variations can affect climate and weather patterns across the world, including the frequency of hurricanes, tropical cyclones and droughts.

In the new study, published Jan. 14 in the journal Science Advances, researchers explored how ENSO affects Arctic sea ice, focusing specifically on the Laptev and East Siberian seas northeast of Russia. The team combed through monthly data on sea surface temperatures and sea ice concentration that were collected between 1979 and 2023 to find patterns between ENSO transitions and sea ice coverage the following year.

The results showed that shifting out of the El Niño phase forms areas of cold surface waters in the central and eastern Pacific near the tropics during the following fall. After the year 2000, the transitions out of El Niño started to speed up, possibly due to interactions with the Pacific Decadal Oscillation, another long-term climate cycle that affects temperatures in the Pacific Ocean.

Those fast transitions made the cold patches even colder. And those cold areas pushed a high-pressure system known as the Western North Pacific Anticyclone (WNPAC) northward towards the Arctic. Pushing the WNPAC north causes another anticyclone to form above the Laptev and East Siberian seas. Together, these connected processes pull heat and moisture from the north Pacific into the Arctic, melting ice along the way.

Prior to 2000, the connection between the cold areas and the WNPAC wasn't strong enough to affect sea ice coverage in the Arctic, the team found.

The changes that have occurred since 2000 are due to natural cycles in Earth's climate, not human activities, the researchers said. But anthropogenic climate change "is putting a big uncertainty on how we predict those multi-decade ice changes," said Xiaojun Yuan, a physical oceanographer at the Columbia University Lamont-Doherty Earth Observatory who was not involved in the study.

Human-caused climate change could override some of the natural patterns observed in these long-term oscillations, Yuan told Live Science.

In future work, the team will investigate the effects of anthropogenic climate change on sea ice in the region, Wang said.

La Niña conditions could develop in the fall and early winter, but they will probably be weak and short-lived, forecasters say.

La Niña is the cold phase of the El Niño-Southern Oscillation (ENSO), a natural climate pattern of atmospheric and sea temperature changes in the tropical Pacific Ocean. During La Niña, the jet stream shifts northward, bringing wetter conditions and cooler winters to the northern U.S., while the southern U.S. experiences drier conditions and warmer winters. A La Niña also tends to ramp up hurricane activity over the Atlantic.

Conditions for this phase briefly developed last winter, but they didn't stick around long enough to be considered an official La Niña event in the historical record. The latest ENSO forecast from the National Weather Service indicated that we could be in for something similar in the coming months.

A period of La Niña conditions is favored for the fall and early winter, and there's a 21% chance that the current July-to-September period will qualify. The likelihood then rises to more than 50% for overlapping 3-month periods between September and January. Still, forecasters aren't expecting massive weather shifts.

"If La Niña forms, it's likely to be weak, meaning La Niña wouldn't exert a strong influence over the winter," Emily Becker, a research professor at the University of Miami and lead writer of the National Oceanic and Atmospheric Administration's ENSO blog, told Live Science in an email.

Related: Watch Hurricane Erin reach Category 5 strength in a blaze of lightning

The ENSO cycle triggers a warm El Niño phase and then a cold La Niña phase every two to seven years, on average, with each phase lasting around nine to 12 months. However, the timing of these phases varies, and they're difficult to predict.

The phases are defined by changes in the sea surface temperature of the Niño region of the east-central Pacific and a shift in atmospheric conditions, which impact the Pacific jet stream. El Niño conditions occur when the sea surface temperature is 0.9 degrees Fahrenheit (0.5 degrees Celsius) higher than the long-term average, while La Niña conditions happen when the sea surface temperature falls 0.9 F below the long-term average.

We were due to enter a La Niña last summer, but the conditions didn't develop until December. That delayed start meant that La Niña didn't have time to gain strength before the onset of winter.

Last year's warmer-than-average ocean temperatures might have played a role in the delay. Earth was in an El Niño between May 2023 and March 2024, which contributed to record-breaking heat during that period. However, the planet has continued to warm with climate change, regardless of what ENSO is doing.

Last winter's La Niña spell didn't make it into the record books because the temperature didn't remain below the 0.9 F threshold for at least five consecutive overlapping seasons — periods of three months. The latest data suggest that La Niña conditions are more likely than not in just three of these upcoming periods across the fall and winter, and thus any spell is unlikely to be an official La Niña.

"It's very possible we'll end up with another winter like 2024-25, with a few months of La Niña conditions, not quite enough to qualify as a La Niña event in our historic record," Becker said. "However, last winter's impacts ended up looking like those we'd expect during a moderately strong La Niña."

In 2023, global marine heatwaves were the biggest, most intense and most persistent on record, a new study reveals. The researchers suggest that these heat waves were driven by climate change and may signal a climate tipping point.

Global marine heatwaves (MHWs) are prolonged periods of unexpectedly warm ocean temperatures. These warm periods can critically threaten marine ecosystems, for instance by leading to coral bleaching and mass marine die offs, and can cause economic challenges by disrupting fisheries and aquaculture. While it's widely accepted that human-driven climate change is making MHWs more destructive, little is known about the ocean dynamics behind the phenomenon.

"Marine heatwaves have emerged globally as one of the most severe threats to marine ecosystems," Ryan Walter, a marine scientist at the California Polytechnic State University who was not involved in the study, told Live Science.

A climate tipping point?

In a study published Thursday (July 24) in the journal Science, the researchers used satellite observations and ocean circulation data to evaluate the MHWs of 2023. They found that the year set new records for MHW temperatures, duration and geographic range — some of which have been measured since the 1950s — with these events lasting four times longer than the historical average and covering 96% of oceans worldwide.

The most intense warming, which occurred in the North Atlantic, tropical Pacific, South Pacific and North Pacific, accounted for 90% of unexpected oceanic heating during 2023. The North Atlantic MHW lasted for 525 days, and the Southwest Pacific MHW broke records for geographic extent and duration.

Related: A Hot Blob in the Pacific Ocean Caused 1 Million Seabirds to Die

The scientists identified several drivers behind the extreme MHWs, including rising solar radiation due to reduced cloud cover, weakened winds and changes in ocean currents.

They suggest that the 2023 MHWs may indicate a fundamental shift in ocean dynamics — which could be early warnings of a climate tipping point. Though there's not a singular definition of a tipping point, most researchers use it to mean the threshold at which certain effects of climate change are irreversible.

It's still uncertain whether or not oceans have reached a crucial tipping point just yet. "Tipping points are difficult to quantify," Walter said. Because the ocean and atmosphere contain many feedback loops, "if you change one thing, it changes another," so making exact predictions of where climate tipping points occur is tricky.

Other factors may also have influenced 2023's record-breaking ocean heat waves. A large El Niño event — a climate cycle in which waters off the eastern Pacific are warmer than usual — in the summer of that year meant "a lot of heat was released from the deeper waters of the ocean into the atmosphere, helping to fuel a lot of these heat waves that the authors write about," Michael McPhaden, a senior scientist at the National Oceanic and Atmospheric Administration who was not involved with the study, told Live Science. For example, in the Tropical Eastern Pacific, temperature anomalies peaked at 34.9 degrees Fahrenheit (1.6 degrees Celsius) during the onset of El Niño, the new paper found.

McPhaden agreed that 2023 was a remarkable year for MHWs and other climate extremes, but said, "I don't consider 2023 to be a tipping point." Though extreme temperature events are on the rise due to climate change, the natural variability that comes with El Niños also affects year-to-year oceanic measurements.

"There are going to be years when things go off the charts, and those are going to be the years when we have big El Niños," McPhaden said.

Marine ecosystems and human livelihoods

Regardless of whether or not 2023 represented a tipping point, extreme MHWs across the globe emphasized the vulnerability of marine ecosystems and human livelihoods that depend on them. MHWs "not only have impacts on foundational ecosystems like kelp forests, seagrasses and coral reefs, all of which provide many valuable ecosystem services and support other species, but they also impact many economies," Walter said.

These extreme events can also lead to the expansion of certain species' habitats — potentially further destabilizing battered ecosystems. Warmer waters off the coast of California, for example, drew equatorial venomous sea snakes to the state. "These sea snakes that typically live in the equatorial Pacific can follow warm waters as far north as Southern and even parts of central California," Walter said.

These extreme MHWs won't be the last. "What you're seeing is a consequence of climate change," McPhaden said. "We're just going to see more temperature extremes in the ocean and in the atmosphere."

After one of the strongest El Niños on record ended in 2024, meteorologists predicted La Niña — the counterpart to this climate pattern — would follow. Signals of a slowly developing and "unusual" La Niña strengthened over the winter, but began to falter in recent months. By March it was dead.

So what happened — and how might that impact this summer's weather and the coming Atlantic hurricane season?

How will climate change impact ENSO patterns?

No one knows how climate change will affect ENSO patterns, but scientists are concerned about the warming oceans and atmosphere.

"Warmer air holds more water. It's fundamental," Becker said. "That's a factor in why we're seeing some hurricanes deposit unbelievable amounts of rain — it's partly due to the higher moisture capacity of the atmosphere."

Warm waters can extend a hurricane season or fuel storms farther north. Once envisioned as coastal threats, storms are increasingly driving inland. For example, Hurricane Helene devastated Appalachian communities hundreds of miles from the sea in 2024. "You're making a better and bigger sponge, and it gets wrung out somewhere," Di Liberto said. "And communities have to deal with incomprehensible amounts of rainfall and flooding."

However, our understanding of hurricanes is incomplete, Done said. Our observational record extends back less than 160 years — just a blink of geologic time. Scientists who have studied the geologic record of ancient cyclones have found evidence of stronger hurricanes making landfall in the distant past, often tied to periods of climate change.

If the present is the key to the past, the past nods back: Earth has seen worse — and with oceans warming fast, scientists warn it may only be a matter of time before historically unprecedented storms strike again.

Archaeologists excavating in Ecuador have discovered the rich burial of a pregnant woman and fetus who died around 1,200 years ago. But the woman's bones revealed that she was bludgeoned and dismembered and that another person's head and burnt offering were placed in the grave, which led archaeologists to suspect she was sacrificed.

"The fact that it was a woman who was pregnant might indicate that women held important positions of power, and thus their power needed to be 'managed,'" Sara Juengst, a bioarchaeologist at the University of North Carolina at Charlotte, told Live Science in an email.

In a study published Thursday (Jan. 23) in the journal Latin American Antiquity, Juengst and colleagues detailed this "enigmatic" burial made during the Manteño period (650 to 1532) of Ecuador's history, which is characterized by complex chiefdoms of coastal people who engaged in agriculture and seafaring and were known to the nearby Inca.

Of the six graves that Juengst and colleagues excavated at the site of Buen Suceso, the one with the pregnant woman stood out as strikingly different.

The young woman, who was roughly 17 to 20 years old, was seven to nine months pregnant when she died, and radiocarbon dating placed her death between 771 and 953. Fractures on her skull suggested that she may have died from a blow to the front of her head. Around the time of her death, someone also violently removed the woman's hands and left leg.

Related: 'An offering to energize the fields': 76 child sacrifice victims, all with their chests cut open, unearthed at burial site in Peru

Human sacrifice was rare for coastal Ecuadorian peoples, the researchers noted in their study. But the items included in the grave made the burial even more unique.

An elaborate array of artifacts buried with the woman included cockle shells placed on her eye orbits, crescent-shaped ornaments made of Spondylus mollusk shells and three obsidian blades around her body, and a crab claw placed on her abdomen. Several of the mollusk shell artifacts were 2,000 years older than the burial and would have been extremely valuable trade items, Juengst said.

Additionally, the skull of a 25- to 35-year-old person had been left in the grave near the pregnant woman's shoulder, and a burnt offering was placed on her chest. Radiocarbon dating of the burnt material showed it was deposited in the grave between 991 and 1025, potentially several centuries after the woman's death.

The sacrifice is especially interesting, Juengst said, because of the contradiction between the "dehumanizing and disempowering" way she was killed and the fact that her grave was full of rich trade goods.

The placement of the artifacts around the woman's body and on her abdomen "suggests protection and special treatment for her and her fetus," Juengst said, especially since Spondylus "is associated with fertility and water, and it was prized by many South American cultures."

In the study, the researchers outlined two scenarios that could explain the woman's death and burial.

Given that the woman died during a period of intense El Niño events, which would have caused issues with crop yields, she may have been sacrificed due to her literal fertility, in the hope of ensuring agricultural success. Many of the artifacts she was buried with evoked watery environments, the researchers noted in the study, further suggesting a link with important natural resources.

But burial patterns within Manteño society also suggested that women had an unusually high amount of political and social power. "If a rival of this woman wanted to take over," Juengst said, "they would need to eliminate her and her unborn offspring, but also still give her honor based on her status."

Benjamin Schaefer, a bioarchaeologist at the University of Illinois Chicago who was not involved in the study, told Live Science in an email that "the distinctive mortuary treatment is noteworthy, but I remain cautious about definitively interpreting it as evidence of sacrifice." Schaefer suggested that future data may strengthen the study's conclusions, "offering deeper insights into a potentially unique sacrificial practice associated with the Manteño."

The researchers noted that, regardless of the burial scenario, the discovery "prompts us to explore new ideas in Ecuadorian archaeology," particularly how "environmental and social factors contributed to the sacrifice and treatment" of the pregnant woman and her fetus.

Officials have announced that an "unusual" La Niña weather pattern (that was supposed to start last summer) is finally underway. However, it is expected to be weaker and shorter than usual.

La Niña is the cold phase of a natural climate pattern called the El Niño Southern Oscillation (ENSO) cycle, which is a pattern of atmospheric and sea temperature changes in the tropical Pacific Ocean that affects global weather and climate.

During a La Niña event, the northern U.S. and Canada typically experience colder and wetter winters, while the southern U.S. becomes warmer and drier, according to the National Oceanic and Atmospheric Administration (NOAA) . La Niña also tends to increase hurricane activity over the Atlantic.

However, the current La Niña arrived later than expected and didn't have time to gain strength before winter started. The conditions for this "unusual" La Niña appeared in December and are likely to persist through to April, NOAA said in a statement on Thursday (Jan. 9).

"We've been expecting La Niña to show up since last spring," NOAA representatives wrote. "While she's dragged her heels, all the pieces came together this past month."

Related: 2024 was the hottest year on record, and the 1st to breach the 1.5 C global warming limit, data reveals

ENSO is a multi-year cycle that triggers a warm El Niño and then a cold La Niña every two to seven years. These events then usually last up to a year each. An El Niño contributed to record-breaking heat in 2023 and 2024, so researchers expected the La Niña to follow. Researchers aren't sure why this La Niña was slow to develop, but warmer-than-average ocean temperatures in 2024 might have played a role, according to NOAA.

La Niña flowchart

NOAA has a flowchart for determining when a La Niña is officially underway. Firstly, tropical Pacific sea-surface temperatures must fall 0.9 degrees Fahrenheit (0.5 degrees Celsius) below the long-term average.

Sea surface temperatures have been within 0.9 degrees F of the average since April, but finally went below the threshold for La Niña in December. NOAA computer models predict that the temperatures will stay below the threshold until spring.

"There's a 59% chance La Niña will persist through February–April, followed by a 60% chance of neutral conditions in March–May," the NOAA representatives wrote.

The temperatures must remain below the threshold for five consecutive seasons — any three-month period — for this La Niña to make it into the NOAA's official historical record, which won't happen if the La Niña fizzles out by March to May. However, ENSO events are notoriously difficult to predict.

Scientists will continue to monitor the tropical Pacific sea-surface temperatures to see how long the La Niña lasts, and investigate the drivers behind this potentially shorter and weaker ENSO event.

"There's a reason our flowchart says 'the next several seasons' instead of providing a specific number: we can make predictions, but it's impossible to know ahead of time exactly how long La Niña conditions will last," NOAA representatives wrote.

The most important Earth news in 2024 was undoubtedly the most depressing: Climate change wreaked havoc around the globe, indirectly causing flooding, drought, wildfires and other extreme weather events.

This year is on track to become the warmest year since records began and the first year that global temperatures have been 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels.

In May, levels of carbon dioxide (CO2) in the atmosphere — as measured from the National Oceanic and Atmospheric Administration's Mauna Loa Observatory — reached a record high of 426.90 parts per million. "Not only is CO2 now at the highest level in millions of years, it is also rising faster than ever," Ralph Keeling, director of the Scripps CO2 Program, said in a statement at the time. Global carbon emissions from fossil fuels also reached a new record high.

All that warming has had disastrous impacts on weather around the globe. The year started with one of the strongest El Niño events on record. That led to a devastating hurricane season that culminated in the deadliest storm to hit the continental U.S. in decades. El Niño also fueled a severe drought in the Amazon. This prolonged drought made the rainforest "more flammable" — an impact that led to the worst wildfire season in nearly 20 years.

And in Spain, torrential rain led to flash floods that killed over 200 people. Scientists also linked this dramatic weather event to climate change.

Climate change devastation edging closer

But some of the scariest news about the planet isn't what happened this year but rather what could occur if we don't stop spewing carbon into the atmosphere. A study published in June suggested ecological tipping points — such as the collapse of the Greenland Ice Sheet and the transformation of the Amazon rainforest into savanna — could be reached in just 15 years if climate change isn't controlled.

In October, scientists penned an open letter warning about the risk posed by the collapse of a key Atlantic current. In it, researchers urged policymakers to address the threat posed by the weakening Atlantic Meridional Overturning Circulation (AMOC) — a giant ocean conveyor belt that transports heat to the Northern Hemisphere, and the breakdown of which could cause temperatures across Europe to plummet.

We've also been warned that we're facing a global water crisis due in part to climate change and chronic mismanagement of resources. "For the first time in human history, we are pushing the global water cycle out of balance," Johan Rockström, director of the Potsdam Institute for Climate Impact Research and co-chair of the Global Commission on the Economics of Water, which produced the report, said in a statement. "Precipitation, the source of all freshwater, can no longer be relied upon due to human caused climate and land use change, undermining the basis for human wellbeing and the global economy."

Still, it's not too late to avert some of the worst of these futures. Michael Mann, presidential distinguished professor and director of the Center for Science, Sustainability and the Media at the University of Pennsylvania, believes it's not too late to stop the worst effects of climate change. "We [climate scientists] have, in some ways, failed to communicate that we can still avert catastrophic climate change," he wrote for Live Science in November.

"We actually decide how bad the climate crisis will get. There is still time to preserve our 'fragile moment,' but the window of opportunity is narrowing. There is urgency in reducing carbon emissions. But there is also still agency on our part in acting."

The worst mass extinction in Earth's history may have been caused by a supercharged El Niño cycle.

New research suggests that an overload of carbon dioxide in the atmosphere led to the climatic shift, which, in turn, killed 90% of the species on Earth around 250 million years ago, at the end of the Permian period. The finding has implications for modern climate science: Researchers don't know how current warming will affect the El Niño-La Niña cycle, but even a fraction of the disruption resulting from the world's worst mass extinction would make life for humanity very difficult.

"When we start pushing ourselves outside of those boundaries that we existed in for hundreds of thousands of years, it becomes uncharted territory," study co-author Alex Farnsworth, a paleoclimate modeler at the University of Bristol in the U.K., told Live Science.

Life flourished in the Permian period (298.9 million to 251.9 million years ago). The supercontinent Pangaea was ringed with lush forests where odd reptiles ranged alongside amphibians and whirring clouds of insects. In the oceans, towering reefs provided homes to spiral-shelled nautiluses, bony fish and sharks.

And then a set of giant volcanic rifts in what is now Siberia erupted. These rifts, known as the Siberian Traps, spewed massive amounts of carbon dioxide into the air. Worse, they erupted in an area rich in coal seams, which also vaporized into the atmosphere. The geological fallout from this eruption has been found in rock layers as far as South Africa.

Related: The 5 mass extinction events that shaped the history of Earth — and the 6th that's happening now

Exactly how the eruptions and the subsequent climate warming translated to mass death has been tricky to pin down. Other large eruptions did not lead to mass extinction, Farnsworth said. Plus, the timing of the deaths was odd: Terrestrial animals started disappearing first, before the worst of the climate warming, and marine species followed.

Study lead author Yadong Sun, an earth scientist at the China University of Geosciences has long been accumulating a database on the teeth of eel-like Permian creatures called conodonts, because the teeth can reveal information about ocean temperatures. His data reveal that, across Panthalassa — an ancient ocean that was the predecessor of the Pacific — the western part of the ocean was initially warmer than the eastern portion. However, this gradient weakened as the end-Permian climate warmed, creating warmer temperatures in the east — just as occurs in today's El Niño events in the Pacific.

The end result, Farnsworth said, was a series of very severe, very long-lasting El Niños. Sun, Farnsworth, and their colleagues modeled the impacts and showed that, on land, these El Niño events would have heightened the already-increasing temperatures caused by carbon-dioxide-forced warming. Forests and species that relied on them would have struggled and died first. Forests remove carbon dioxide from the atmosphere, so their loss allowed even more heat-trapping carbon to stay aloft.

"You get this runaway positive feedback in the system," Farnsworth said. The heat in the atmosphere eventually heated Panthalassa up to 104 degrees Fahrenheit (40 degrees Celsius) in the tropics, which is outside the survival envelope for most ocean organisms, the researchers reported Thursday (Sept. 12) in the journal Science.

"This is the best paper I've seen yet linking what happened in the Permian to the present day," said Peter Ward, a University of Washington paleontologist who was not involved in the study but researches the end-Permian extinction. Ward called the implications of the paper "terrifying." The Siberian Traps put far more carbon dioxide into the atmosphere than humanity has — probably around 2,500 parts per million (ppm), compared with 419 ppm today, Farnsworth said – but humanity is injecting carbon at a faster rate.

"What this paper is just an end member of how bad it can get, but even a little bit of what the Permian did is terrible for society," Ward told Live Science. "Our civilization requires stability, and we are creating gigantic instability in the Earth system."

For a few months this summer, a large strip of Atlantic Ocean along the equator cooled at record speed. Though the cold patch is now warming its way back to normal, scientists are still baffled by what caused the dramatic cooling in the first place.

The anomalous cold patch, which is confined to a stretch of ocean spanning several degrees north and south of the equator, formed in early June following a monthslong streak of the warmest surface waters in more than 40 years. While that region is known to swing between cold and warm phases every few years, the rate at which it plunged from record high to low this time is "really unprecedented," Franz Tuchen, a postdoctoral research associate at the University of Miami in Florida who is tracking the event, told Live Science.

"We are still scratching our heads as to what's actually happening," Michael McPhaden, a senior scientist with the National Oceanic and Atmospheric Administration (NOAA) who oversees an array of buoys in the tropics that have been gathering real-time data of the cold patch, told Live Science. "It could be some transient feature that has developed from processes that we don't quite understand."

Sea surface temperatures in the eastern equatorial Atlantic were the hottest in February and March, when they exceeded 86 degrees Fahrenheit (30 degrees Celsius) — the warmest months on record since 1982. When June rolled in, temperatures began plummeting mysteriously, reaching their coolest in late July at 77 F (25 C), Tuchen recently wrote in a blog post.

Forecasts showed the cooling event may be on the verge of developing into an Atlantic Niña, a regional climate pattern which tends to increase rainfall over western Africa and decrease rainfall in northeastern Brazil as well as countries hugging the Gulf of Guinea, including Ghana, Nigeria and Cameroon. The phenomenon, which isn't as powerful as the La Niña counterpart in the Pacific, and hasn't occurred since 2013, would have been declared if the colder-than-average temperatures persisted for three months, until the end of August.

Related: Gulf Stream's fate to be decided by climate 'tug-of-war'

However, the cold pocket of water has been warming in recent weeks, so "the verdict is already quite certain that it's not gonna be classified as Atlantic Niña," said Tuchen.

Nevertheless, figuring out just what caused the dramatic cooling would allow scientists to better understand the quirks of Earth's climate, which can eventually benefit weather forecasting, Tuchen said. But none of the expected processes stand out so far.

"Something else going on"

Cooler surface waters are typically accompanied by stronger trade winds, which flow near the equator and are the most influential drivers of Niñas because they sweep away warm surface waters and allow deeper, cooler water to rise through a process known as equatorial upwelling. Puzzlingly, the recent cold region coincides with weaker winds southeast of the equator, which "are doing the opposite of what they should be doing if they were the reason for the cooling," said Tuchen. “At the moment, we believe that the winds are actually responding to the cooling.”

McPhaden noted some anomalously strong winds that had developed to the west of the cold patch in May may have kickstarted the cooling at record speed, but those winds "haven't increased as much as the temperature has dropped," said McPhaden. "There's something else going on."

Scientists have modeled a handful of possible climate processes to try to explain the observed cold region, such as enormously strong heat fluxes in the atmosphere or sudden changes in ocean and wind currents. "From what we see, these are not obvious drivers of this cooling event," said Tuchen.

While unprecedented, the recent dramatic cooling is not likely to be caused by human-driven climate change. "I can't rule it out," said McPhaden. "But at first blush, this is just a natural variation of the climate system over the equatorial Atlantic."

Using data from satellites, oceanic buoys and other meteorological tools, Tuchen and McPhaden are among several climate scientists who are intently tracking the cold patch and any forthcoming effects it would have on the surrounding continents — which could take months to become apparent.

"It's potentially going to be a consequential event," said McPhaden. "We just have to watch and see what happens."

Researchers have simulated an El Niño-like climate pattern in the Pacific Ocean and found that it affects winds and sea temperatures across the entire Southern Hemisphere.

The pattern begins with warming seas near New Zealand and Australia that trigger a wave of temperature changes south of the equator. 

Climate scientists have known about a pattern affecting sea surface temperature fluctuations in the region since 2021, but they didn't understand how it worked. In a new study published July 6 in the Journal of Geophysical Research: Oceans, researchers successfully simulated the pattern for the first time. They named the climate phenomenon the "Southern Hemisphere Circumpolar Wavenumber-4 Pattern" (SST-W4).

"This discovery is like finding a new switch in Earth's climate," study lead author Balaji Senapati, a postdoctoral researcher in climate dynamics at the University of Reading in the U.K., said in a statement. "It shows that a relatively small area of the ocean can have wide-reaching effects on global weather and climate patterns." 

Related: All El Niños will be extreme if climate change isn't slowed, study suggests

This SST-W4 pattern shares some characteristics with El Niño, a climate cycle in the Pacific Ocean that influences weather patterns worldwide and has a warming effect. However, the SST-W4 pattern occurs independently of El Niño and other known weather systems.

To track the pattern, the researchers used a climate emulator called SINTEX-F2 to simulate 300 years of climate conditions, according to the study. The modeling revealed year-to-year fluctuations in sea surface temperatures between December and February, caused by a circling pattern of four alternating warm and cool areas.

The wave-like pattern ripples out from its starting point in the southwestern subtropical Pacific and travels around the Southern Hemisphere on strong winds, according to the statement. 

Now that researchers have simulated the SST-W4 pattern, they can better predict weather events south of the equator.

"Understanding this new weather system could greatly improve weather forecasting and climate prediction, especially in the Southern Hemisphere," Senapati said. "It might help explain climate changes that were previously mysterious and could improve our ability to predict extreme weather and climate events." 

Extreme El Niño events may become the new normal, new research suggests. 

During these strong El Niños, the west coast of South America experiences heavy rainfall that can lead to floods and landslides, while western Pacific landmasses such as Indonesia and Australia undergo periods of drought. 

The world is on track to warm 5.2 degrees Fahrenheit (2.9 degrees Celsius) by 2100 if current greenhouse gas emission trends continue, according to a 2023 United Nations report. But the new modeling study suggests that if the planet warms a little more than that — 6.6 F (3.7 C) — 90% of El Niños will rival the strongest ones on record, such as the El Niño that occurred between 1997 and 1998. That El Niño was responsible for 23,000 deaths and billions of dollars in damage due to storms, droughts, floods and disease outbreaks caused by flooding, according to a 1999 estimate published in the journal Science.

"If we would end up in a state where each El Niño is an extreme eastern Pacific El Niño, this would just have huge social economic impacts in the Pacific region," said the study's lead author, Tobias Bayr, who conducted the research while a scientist at the GEOMAR Helmholtz Centre for Ocean Research in Germany. 

Related: 'The last 12 months have broken records like never before': Earth exceeds 1.5 C warming every month for entire year

The effect of climate change on the El Niño and La Niña cycle has been hotly debated. Some early models suggested that a warming world might be in a permanent state of El Niño, in which the trade winds that blow around the equator weaken and the waters of the eastern Pacific get warmer. 

This ocean warming has broad-ranging climate and weather impacts. Heat from the water leaks into the atmosphere, raising average global temperatures. The jet stream over North America moves southward, drying the Pacific Northwest and causing increased rainfall in the southern portion of the U.S. Some of the most dire impacts are in the Southern Hemisphere, with extreme precipitation in South America and drought and wildfire on the opposite side of the Pacific.

Not all climate models agreed that a permanent El Niño was baked in by climate change, though, Bayr told Live Science. He and his colleagues used a climate model that is particularly good at representing the complex patterns of the El Niño/La Niña cycle. They found that warming did not cause permanent El Niño but rather stronger and more frequent El Niño conditions. 

Under today's conditions, the model predicted eight or nine extreme El Niños per century. ("Extreme" El Niños are defined by the amount of precipitation in the mid-tropical Pacific during the Northern Hemisphere's winter.) With 6.6 F of warming, this number skyrocketed to 26 extreme El Niños every 100 years, on a nearly regular four-year oscillation. In these conditions, the researchers found, 90.4% of El Niños would be extreme by today's standards. These extremes are due to extra-warm conditions in the eastern Pacific over the equator, the model showed. 

The findings, published July 4 in the journal Geophysical Research Letters, come from just one model, Bayr cautioned, so they need to be confirmed in other climate models. But the study reopens the question of whether El Niño is a "tipping point" in the climate system. Climate tipping points are conditions that change rapidly in new climate conditions but don't easily flip back if the temperature cools again. The new research suggests this could be the case for El Niño, which wouldn't recover to a more "normal" pattern for more than a century if it flipped to an all-extreme version of the cycle, Bayr and his colleagues wrote. 

"It has a really very different behavior in the colder and the warmer climate and therefore we say that there is a tipping point-like behavior," Bayr said. "It would be good if other institutes could also do similar experiments and investigate if other models show a similar behavior."

El Niño is likely to give way soon, ushering in a quick switch to its opposite atmospheric and ocean pattern, La Niña. 

For the U.S., this climatological flip-flop will likely mean a greater risk of major hurricanes in the Atlantic as well as areas of drier-than-usual weather in the southern portions of the country. Globally, La Niña usually leads to declining temperatures, but the lag in when the effects take place means that 2024 will likely still be a top-five year for temperature in climate history, said Tom Di Liberto, a climate scientist at the National Oceanic and Atmospheric Administration (NOAA). 

"All signs suggest that 2024 is going to be another warm year," Di Liberto told Live Science. 

El Niño and La Niña describe opposing patterns in the trade winds that encircle the equator, blowing west from South America toward Asia. In a neutral year, when neither pattern is in play, these trade winds push warm water westward, which drives cool ocean water up from the depths to replace it. 

When El Niño is in play, the trade winds weaken, so the eastern Pacific, along the west coast of North and South America, stays warmer. The effect, according to NOAA, is that the jet stream moves southward, drying Canada and the northern U.S. but bringing moisture to the southern portions of the U.S. 

Related: Why don't hurricanes form at the equator?

In a La Niña year, the trade winds strengthen, pushing warm water toward Asia and increasing the upwelling of cold water off the Pacific coast of the Americas. The jet stream moves northward, drying the Southwest and Southeast and bringing wetter weather to the Pacific Northwest and the Great Lakes. 

The El Niño pattern has officially been active since June 2023, but NOAA's Climate Prediction Center now reports that the pattern is weakening, with an 85% chance of a switch to neutral conditions before June. La Niña is then expected to roar back, with a 60% chance of La Niña conditions between June and August, the National Centers for Environmental Prediction reports.

"When it comes to El Niños of this strength, moderate to strong, it"s not uncommon to see these events end rapidly and then shift into La Niña rapidly," Di Liberto said. 

Ocean measurements currently show warm surface temperatures in the Pacific, Di Liberto said, but below-average cold water beneath. Once that cold water hits the surface, the switch will happen quickly, he said. 

The flip from El Niño to La Niña raises the risk of a strong upcoming hurricane season, said Alex DesRosiers, a doctoral candidate in atmospheric science at Colorado State University. During El Niño, rising heat from the eastern Pacific flows into the upper atmosphere, leading to stronger winds at high altitudes. This creates vertical wind shear — a difference in wind speed and direction at the surface versus higher in the atmosphere. And vertical wind shear, DesRosiers told Live Science, "can really act to tear apart hurricanes as they try to form." 

During La Niña, the upper atmosphere winds calm, reducing wind shear. This allows the convection of warm, moist air from the ocean surface to form big storms. 

"As we move into La Niña, the atmosphere becomes more supportive of allowing storms to bubble up and intensify," DesRosiers said. 

As a result of the expected La Niña and current extremely warm Atlantic Ocean surface temperatures, CSU's Tropical Weather & Climate Research team is currently predicting a very active Atlantic hurricane season, with a forecast of 23 named storms (versus the average of 14.4) and five hurricanes of Category 3 or higher (versus the average of 3.2). This year may look similar to 2010 and 2020, both of which were busy storm seasons, although it's not guaranteed that strong storms will impact land, DesRosiers said. 

All of these climatic patterns are taking place against a backdrop of rising ocean and surface temperatures. So, while La Niña usually brings cooler-than-average temperatures to the northern U.S., this region could still experience a scorching summer due to the background effects of climate change, Di Liberto said. 

Similarly, although 2023 was an El Niño year, which should suppress hurricanes, it saw an above-average hurricane season, DesRosiers said. This busy storm season might be due, in part, to 2023 being the warmest year on record. 

"With an Atlantic that is this warm," he said, "we're kind of in uncharted territory." 

The polar vortex circling the Arctic is swirling in the wrong direction after surprise warming in the upper atmosphere triggered a major reversal event earlier this month. It is one of the most extreme atmospheric U-turns seen in recent memory.

In the past, disruptions to the polar vortex — a rotating mass of cold air that circles the Arctic — have triggered extremely cold weather and storms across large parts of the U.S.. 

The current change in the vortex's direction probably won't lead to a similar "big freeze." But the sudden switch-up has caused a record-breaking "ozone spike" above the North Pole.

The polar vortex is most prominent during winter months and extends into the stratosphere — the second layer of the atmosphere up to around 30 miles (50 kilometers) above the surface. The vortex spins counterclockwise with wind speeds of around 155 mph (250 km/h), which is around the same speed as a Category 5 hurricane, according to the U.K. Met Office. A similar vortex also encircles Antarctica during the southern winter.

Polar vortices occasionally reverse temporarily. These events can last for days, weeks or months and are caused by sudden stratospheric warming (SSW), when the temperatures in the stratosphere climb by as much as 90 degrees Fahrenheit (50 degrees Celsius) in the space of a couple of days, according to the Met Office. 

Related: 'One of the biggest on record': Ozone hole bigger than North America opens above Antarctica

The sudden warming is caused by "planetary waves" in the atmosphere — compression waves formed when air rises into a region of different density and is pushed back downward by the force of Earth's spin. This process disrupts or reverses the vortex flow.

The current reversal event in the Arctic began on March 4. However, the winds are starting to slow down, hinting that the vortex will return to its normal trajectory soon, Spaceweather.com reported.

"It was a substantial reversal," Amy Butler, a climate scientist at the National Oceanic and Atmospheric Administration (NOAA) and author of NOAA's new polar vortex blog, told Spaceweather.com. The speed of the reversed winds puts the event in the top six on record, she added.

Disruptions to the polar vortex can impact weather in the U.S., such as in 2019 when a massive cold front descended across the Midwest. These extreme weather events occur when the polar vortex deforms the jet stream — an air current that surrounds the polar vortex — exposing lower latitudes to large blobs of icy Arctic air. 

This month's disruption did not change the shape of the jet stream, so weather patterns are expected to remain largely unaffected, according to Spaceweather.com. 

However, the change in air temperature around the Arctic has sucked up large amounts of ozone from lower latitudes, creating a temporary ozone spike — the opposite of an ozone hole. Currently, there is more ozone surrounding the Arctic than at this time during any other year on record, according to Spaceweather.com. However, this ozone spike will disappear after the polar vortex returns to normal 

The current reversal is the second of its kind this year, following a smaller event in January that did cause a brief cold snap in some states, Butler wrote in NOAA's polar vortex blog.

Historical records show that SSW events are more likely to occur during El Niño or La Niña, the two contrasting phases of a natural cycle of planet-wide warming and cooling. During these phases, global weather systems become more unstable, which sets the stage for more frequent reversal events, Butler wrote in the NOAA blog.

We are currently in the midst of a major El Niño, which could make further reversals or disruptions more likely over the next year or so.

Before the year has even come to a close, climate experts are certain that 2023 will be the hottest year in recorded history. And while several factors are impacting this year's record heat, researchers say human-caused climate change is overwhelmingly responsible.

On Dec. 6, the Copernicus Climate Change Service (C3S) — part of the European Union's space program — revealed that this year's boreal autumn, or September to November in the Northern Hemisphere, has been the warmest since their records began in 1940, with temperatures reaching 0.6 degrees Fahrenheit (0.32 degrees Celsius) higher than ever before.

This year, we have already had the warmest summer on record, partly due to a record-shattering heatwave that included a sequence of three of the hottest-ever days globally. During 2023, six individual months also broke their global temperature records, according to C3S, and Antarctica's sea ice reached its lowest levels since records began.   

So far this year, average global temperatures have been 2.6 F (1.46 C) higher than temperatures in preindustrial times and 0.2 F (0.13 C) higher than January to November in 2016, which is the current hottest year on record, according to C3S. 

These "extraordinary" temperatures mean that 2023 will be "the warmest year in recorded history," C3S deputy director Samantha Burgess said in a statement.

Related: 15 unexpected effects of climate change

The researchers note that the unusually warm boreal autumn was partly caused by the latest El Niño event — a phenomenon where warmer water near the equator triggers warmer global air temperatures — that officially began in June. El Niño will continue into next year, which means that 2024 will likely be just as warm as 2023.

For the last three years, global temperatures were kept in check by a triple-dip La Niña event, which has the opposite effects to El Niño. But without La Niña, sea surface temperatures have climbed higher than ever before. 

Some other experts have suggested that the January 2022 eruption of Tonga's underwater volcano, which pumped record levels of water vapor into the atmosphere, may be partly responsible for this year's record heat by trapping more heat in the atmosphere. However, these claims have been largely debunked by researchers.

Despite these factors, the major cause of climbing temperatures is global warming caused by runaway greenhouse gas emissions, which have trapped more than 25 billion atomic bombs' worth of energy in our atmosphere over the last 50 years, the researchers wrote. This excess energy has not only caused air temperatures to skyrocket but also makes extreme events such as El Niño much more unpredictable and potentially damaging, they said. 

And the problem is getting worse. On Dec. 4, scientists at the United Nations Climate Change Conference of the Parties (COP28) announced that global carbon emissions reached a new high this year.

"As long as greenhouse gas concentrations keep rising we can't expect different outcomes from those seen this year," C3S director Carlo Buontempo said in the statement.

The effects of global warming are becoming more obvious. In 2023, research revealed that climate change is causing major U.S. cities to sink and more than half of the world's largest lakes and reservoirs to shrink. Studies also predicted that the Gulf Stream, which plays a vital role in ocean circulation, could collapse by as early as 2025, and that rising sea levels could swamp the U.S. coastline by 2050.

However, scientists say that we still have time to prevent further disaster.

Leading climate change expert Michael Mann, director of the Center for Science, Sustainability and the Media at the University of Pennsylvania, recently wrote in an opinion piece for Live Science that "we can still stop the worst effects of climate change" if we stop emitting greenhouse gases as soon as possible.

There is still time to preserve what we have now, Mann wrote. "But the window of opportunity is narrowing."

A weird blob of warm water that has appeared in the western Pacific seems to be making this year's "strong" El Niño behave unexpectedly, reports The Washington Post.

The blob is located in the west-central Pacific, near the International Dateline — a north-south boundary that separates two consecutive calendar dates — Paul Roundy, a professor of atmospheric science at the University of Albany, told the newspaper.   

El Niño usually triggers warming in the eastern tropical Pacific, which in turn shapes atmospheric conditions and weather patterns across North America and around the world. While this year's El Niño event comes as no surprise — experts warned it could be a big one in May — the atmospheric response "looks nothing like other recent strong El Niño events," Todd Crawford, a meteorologist at the weather forecasting consultancy Atmospheric G2, wrote on X, formerly known as Twitter, on Nov. 8.

During typical El Niño years, warm waters in the eastern tropical Pacific heat the air above and cause it to rise. But that isn't happening now, experts told the Washington Post, because air is rising in the western Pacific instead. Some of this air may be blowing east and suppressing the rising motion usually seen there, they said.

Related: A strong El Niño is coming this winter. What does that mean?

Rising air creates low pressure conditions associated with showers and thunderstorms. The warm blob in the western Pacific is causing "more tropical rain to fall there, which in turn reduces the intensity of the rainfall farther east because the air that rises in the west Pacific thunderstorms subsides back toward the surface farther east, drying the atmosphere," Roundy said.

El Niño may be behaving abnormally this year because of lingering effects from a rare "triple dip" of La Niña events — El Niño's chilly counterpart. La Niña produced a sustained cooling effect around the equator and eastern tropical Pacific over the past three years and probably "hasn't completely washed out," Crawford told the Washington Post. High ocean temperatures resulting from human-caused climate change may also be to blame for the unusual warmth in the western Pacific, according to the newspaper. 

Strong El Niño conditions could persist through the Northern Hemisphere winter and last until spring 2024, the National Weather Service said in its latest advisory, with a 35% chance the event could become "historically strong" from November to January. "Strong El Niño events increase the likelihood of El Niño-related climate anomalies but do not necessarily equate to strong impacts," representatives wrote in the advisory on Nov. 9.

El Niño winters typically see masses of warm air building across Alaska, western Canada and the northern U.S., the Washington Post reported. Cooler, wetter conditions usually predominate in the southern states.

Similar conditions may still arise this winter, despite the warm blob's appearance, Roundy said. "This interference of west Pacific warmth appears to be declining," he said, adding that a body of warm water forming to the east of the International Dateline may trigger heavier rainfall there.

A burst of westerly winds could also push warm water sitting on the blob's surface toward the eastern Pacific, Roundy noted. This would expose cooler layers of water underneath and "encourage more normal strong El Niño signals to emerge this winter," he said.

The drought plaguing the Amazon is a worrying portrait of the climate challenges facing the world. The combination of the El Niño phenomenon and anthropogenic climate change has played a significant role in accentuating this extreme weather event. The Amazon region, known for its lush rainforest and flowing rivers, is facing a critical situation due to a lack of rainfall and rising temperatures.

This phenomenon, never recorded at this intensity, has affected biodiversity and human life in eight Amazonian states. The drought has already killed more than 140 dolphins, including pink dolphins and tucuxis, also known as grey dolphins. The mortality of fish and other aquatic animals is also high. The low volume of the rivers affects the human supply, causing a lack of drinking water and food in all the small villages, even those located on the banks of the big rivers. Of the 62 municipalities in the state of Amazonas, 42 are in a state of emergency, 18 are in a state of alert and only two are in a normal situation.

The El Niño phenomenon has a direct influence on the Amazon drought. It manifests itself in the abnormal warming of the surface waters of the Pacific Ocean, affecting the rainfall regime in various parts of the world. In the case of the Amazon region, the drought is exacerbated by a decrease in humidity and a lack of rainfall, damaging the vegetation, fauna and local communities that depend on natural resources.

However, anthropogenic climate change is making the situation even worse. Rampant deforestation, driven by agricultural expansion and logging activity, reduces the Amazon rainforest's ability to regulate the climate and retain moisture. In addition, the destruction of vast areas of vegetation contributes to rising temperatures, creating a cycle of even more accentuated droughts.

Deforestation and mining, major factors

Deforestation has been particularly devastating in the region of Highway BR-319, in the south of Amazonas state, driven by land grabbing which has provided cheap land to cattle ranchers from other states. In turn, this deforestation has increased the number of fires that feed back into the climate crisis. When they occur near riverbanks, deforestation also intensifies the phenomenon known as fallen land, which has drastically affected the draught of rivers and is already significantly jeopardising navigation and logistics, mainly affecting villages in the interior of the Amazon, which are already suffering from shortages.

Another factor that has played a significant role in affecting navigation is mining activity. Disorganised mineral extraction has created banks of land that are harmful to navigation and which, in the critical scenario of drought, have caused many vessels to run aground.

The impact of hydroelectric dams

Hydroelectric dams also play a role in contributing to the drought scenario, especially on the Madeira River. This is mainly due to the decomposition of organic matter in reservoirs created by dams, which releases methane, a potent greenhouse gas, into the atmosphere. In addition, deforestation associated with the construction of dams, as well as soil degradation and erosion resulting from the alteration of aquatic and terrestrial ecosystems, can increase emissions of carbon dioxide (CO2) and other pollutants, contributing to the impact of hydroelectric dams on climate change.

The Madeira River, now at its lowest level in almost 60 years, has been drastically affected and transformed by the Jirau and Santo Antônio hydroelectric dams. This was due to the drastic alteration of the river's natural flow caused by the damming of water for power generation. When water is dammed, a reservoir is formed that retains part of the water that would normally flow along the river. This diversion of the flow directly affects the region's aquatic and terrestrial ecosystems, since the basin's hydrological cycle is interrupted. The reduction in the volume of water in the Madeira River, for example, can lead to prolonged periods of drought, affecting not only aquatic fauna and riparian habitats, but also local communities that depend on the river for their livelihoods.

In addition, the construction and operation of hydroelectric dams in the Amazon often involves the clearing of significant areas of forest for the construction of dams and associated infrastructure. Deforestation contributes to a reduction in evapotranspiration, which is a crucial process for water balance in the region. With fewer trees to release water into the atmosphere, the Amazon becomes more susceptible to drought. The combination of these factors results in a significant impact on the region, making hydroelectric dams one of the causes of drought in the Amazon, particularly on the Madeira River, with worrying environmental and social consequences.

What can still be done

In order to combat the extreme drought in the Amazon and its devastating effects, it is essential to adopt strict measures to curb deforestation and illegal mining in the region, and for the federal government to review major undertakings such as hydroelectric dams and roads, such as the BR-319 motorway.

Many politicians have argued that the road, if paved, could reduce the state’s isolation, especially during droughts. However, this is a fallacious argument, because connecting the most isolated municipalities would require hundreds of kilometres of side roads, which would further increase deforestation and aggravate the climate crisis.

In addition, the BR-319 motorway has become a spearhead that cuts through one of the most conserved blocks of forest, linking the central Amazon, which is still preserved, to the "arc of Amazonian deforestation", a region that concentrates most of the climate anomalies in the entire biome.

Ecosystem on the edge

In a recent study published in the renowned journal Conservation Biology, it was shown that deforestation in the Amazon is already impacting ecosystem services that are essential for Brazil, such as the Amazon’s flying rivers. This scientific data shows that we are already at the threshold of deforestation and environmental degradation tolerated by the Amazon, and more forceful action needs to be taken now.

Part of this responsibility lies now in the hands of President Lula, in reviewing major developments in the Amazon, such as hydroelectric dams and highways like the BR-319. In addition, it is essential to institute a zero deforestation policy that should begin this year, and not in 2030, when it will be too late. Furthermore, it is crucial that the international community and local governments work together to reduce greenhouse gas emissions and tackle climate change effectively. Only with coordinated and decisive action will we be able to mitigate the impacts of drought in the Amazon and protect this unique ecosystem that plays a vital role in regulating the global climate.

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

Winter is still weeks away, but meteorologists are already talking about a snowy winter ahead in the southern Rockies and the Sierra Nevada. They anticipate more storms in the U.S. South and Northeast, and warmer, drier conditions across the already dry Pacific Northwest and the upper Midwest.

One phrase comes up repeatedly with these projections: a strong El Niño is coming.

It sounds ominous. But what does that actually mean? We asked Aaron Levine, an atmospheric scientist at the University of Washington whose research focuses on El Niño.

What is a strong El Niño?

During a normal year, the warmest sea surface temperatures are in the western Pacific and the Indian Ocean, in what's known as the Indo-Western Pacific warm pool.

But every few years, the trade winds that blow from east to west weaken, allowing that warm water to slosh eastward and pile up along the equator. The warm water causes the air above it to warm and rise, fueling precipitation in the central Pacific and shifting atmospheric circulation patterns across the basin.

This pattern is known as El Niño, and it can affect weather around the world.

A strong El Niño, in the most basic definition, occurs once the average sea surface temperature in the equatorial Pacific is at least 1.5 degrees Celsius (2.7 Fahrenheit) warmer than normal. It's measured in an imaginary box along the equator, roughly south of Hawaii, known as the Nino 3.4 Index.

But El Niño is a coupled ocean-atmosphere phenomenon, and the atmosphere also plays a crucial role.

What has been surprising about this year's El Niño — and still is — is that the atmosphere hasn't responded as much as we would have expected based on the rising sea surface temperatures.

Is that why El Niño didn’t affect the 2023 hurricane season the way forecasts expected?

The 2023 Atlantic hurricane season is a good example. Forecasters often use El Niño as a predictor of wind shear, which can tear apart Atlantic hurricanes. But with the atmosphere not responding to the warmer water right away, the impact on Atlantic hurricanes was lessened and it turned out to be a busy season.

The atmosphere is what transmits El Niño’s impact. Heat from the warm ocean water causes the air above it to warm and rise, which fuels precipitation. That air sinks again over cooler water.

The rising and sinking creates giant loops in the atmosphere called the Walker Circulation. When the warm pool's water shifts eastward, that also shifts where the rising and sinking motions happen. The atmosphere reacts to this change like ripples in a pond when you throw a stone in. These ripples affect the jet stream, which steers weather patterns in the U.S.

This year, in comparison with other large El Niño events — such as 1982-83, 1997-98 and 2015-16 — we're not seeing the same change in where the precipitation is happening. It's taking much longer to develop, and it's not as strong.

Part of that, presumably, is related to the whole tropics being very, very warm. But this is still an emerging field of research.

How El Niño will change with global warming is a big and open question. El Niño only happens every few years, and there's a fair amount of variability between events, so just getting a baseline is tough.

What does a strong El Niño typically mean for US weather?

During a typical El Niño winter, the U.S. South and Southwest are cooler and wetter, and the Northwest is warmer and drier. The upper Midwest tends to be drier, while the Northeast tends to be a little wetter.

The likelihood and the intensity generally scale with the strength of the El Niño event.

El Niño has traditionally been good for the mountain snowpack in California, which the state relies for a large percentage of its water. But it is often not so good for the Pacific Northwest snowpack.

The jet stream plays a role in that shift. When the polar jet stream is either displaced very far northward or southward, storms that would normally move through Washington or British Columbia are steered to California and Oregon instead.

What do the forecasts show for 2023?

Whether forecasters think a strong El Niño will develop depends on whose forecast model they trust.

This past spring, the dynamical forecast models were already very confident about the potential for a strong El Niño developing. These are big models that solve basic physics equations, starting with current oceanic and atmospheric conditions.

However, statistical models, which use statistical predictors of El Niño calculated from historical observations, were less certain.

Even in the most recent forecast model outlook, the dynamical forecast models were predicting a stronger El Niño than the statistical models were.

If you go by just a sea surface temperature-based El Niño index, the forecast is for a fairly strong El Niño.

But the indices that incorporate the atmosphere are not responding in the same way. We've seen atmospheric anomalies — as measured by cloud height monitored by satellites or sea-level pressure at monitoring stations — on and off in the Pacific since May and June, but not in a very robust fashion. Even in September, they were nowhere near as large as they were in 1982, in terms of overall magnitude.

We'll see if the atmosphere catches up by wintertime, when El Niño peaks.

How long do El Niños last?

Often during El Niño events — particularly strong El Niño events — the sea surface temperature anomalies collapse really quickly during the Northern Hemisphere spring. Almost all end in April or May.

One reason is that El Niño sows the seeds of its own demise. When El Niño happens, it uses up that warm water and the warm water volume shrinks. Eventually, it has eroded its fuel.

The surface can stay warm for a while, but once the heat from the subsurface is gone and the trade winds return, the El Niño event collapses. At the end of past El Niño events, the sea surface anomaly dropped very fast and we saw conditions typically switch to La Niña — El Niño’s cooler opposite.

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

This year's El Niño may drive ocean temperatures to "substantially exceed" those recorded during the last strong event in early 2016, scientists have warned.

The National Oceanic and Atmospheric Administration's (NOAA) latest El Niño update also says there is a more than 95% chance the event will last through to February 2024, with far-reaching climate impacts.

"El Niño is anticipated to continue through the Northern Hemisphere winter," NOAA staff wrote in the update. "Our global climate models are predicting that the warmer-than-average Pacific ocean conditions will not only last through the winter, but continue to increase."

Scientists officially announced the onset of El Niño in early June. El Niño is an ocean-warming event that typically occurs every two to seven years in the central and eastern Pacific, driving air temperatures up around the globe.

Its strongest climate impacts are usually felt during the Northern Hemisphere's winter and early spring, bringing more rain and storms across the southern U.S., southeastern South America, the Horn of Africa and eastern Asia. In other parts of the world, such as southeastern Africa and Indonesia, El Niño leads to drier conditions and may increase the risk of drought.

Related: Florida waters now 'bona fide bathtub conditions' as heat dome engulfs state

To track El Niño's progress, scientists measured sea surface temperatures in the east-central tropical Pacific Ocean. Abnormally high temperatures seem to confirm early predictions that this year's event could be a big one. Atmospheric conditions are also consistent with a long-lasting El Niño, according to NOAA.

"El Niño is a coupled phenomenon, meaning the changes we see in the ocean surface temperatures must be matched by changes in the atmospheric patterns above the tropical Pacific," the update said. More rain and clouds over the central Pacific, as well as weak pressure in the east and reduced trade wind activity in the west, suggest "the system is engaged and that these conditions will last through the winter," staff added.

Sea surface temperatures in the east-central tropical Pacific exceeded the long-term average for 1991 to 2020 by 1.8 degrees Fahrenheit (1 degree Celsius) throughout the month of July. Temperatures from May to July — a three-month average called the Oceanic Niño Index — were also 1.4 F (0.8 C) higher than usual and marked the second warmer-than-average Oceanic Niño Index in a row.

"We need to see five consecutive three-month averages above this threshold before these periods will be considered a historical 'El Niño episode,'" the update said. "Two is a good start."

There is "a good chance" the Oceanic Niño Index will match or exceed the threshold for a "strong" El Niño, the update added.

And forecasters are now confident the event will remain strong through to next year, although this doesn't necessarily equate to strong impacts locally, they noted

El Niño affects global weather patterns, as well as the Atlantic and Pacific hurricane seasons. The event usually dampens hurricanes over the Atlantic Ocean, but this year's sizzling water temperatures could mitigate this dampening effect , according to NOAA's Climate Prediction Center.

While a hurricane update in May predicted a 30% chance of higher activity over the Atlantic, the latest forecast said there is a 60% chance of an "above normal season," with up to 21 named storms and five major hurricanes.

For the past three days, from Monday through Wednesday (July 3-5), global temperatures have either broken or matched records for the hottest day on Earth since at least 1979, according to the University of Maine's Climate Reanalyzer, a tool that compiles data and models to measure the global atmosphere. Monday's average worldwide temperature climbed to 62.6 degrees Fahrenheit (17 degrees Celsius), while Tuesday (July 4) and Wednesday (July 5) both hit 62.9 F (17.2 C). 

While these temperatures may not seem particularly high, they represent the global average, which combines measurements from both the Northern Hemisphere and the Southern Hemisphere, where it is currently winter. The three-day hot streak was likely fueled by climate change, experts say, as well as the arrival of El Niño, a climate pattern characterized by warm sea-surface temperatures around the equator toward the Pacific coast of South America. El Niño events can change atmospheric conditions enough to boost heat waves around the world, research shows. 

"It's helpful to remember that the Pacific Ocean covers almost half the planet," said Kim Cobb, a climate scientist at the Georgia Institute of Technology, told Live Science. During an El Niño event, "you're talking about a very large portion of the planet that is … pushing temperatures up on the global average."

Related: NASA spots sign of El Niño from space: 'If it's a big one, the globe will see record warming'

The Climate Reanalyzer pulls data from atmospheric measurement tools, surface observations and satellites to estimate the global average temperature. Though the values are not considered an official government estimate, the National Oceanic and Atmospheric Administration indicated it would consider these measurements when calculating its temperature record, according to The Associated Press. 

July isn't the only month breaking records: The European Union's Copernicus Climate Change Service found that last month was the hottest June on record, an average of 0.36 F (0.2 C) warmer than June 2022. Dangerous heat waves have plagued southeastern U.S. states during the past week, as well as Texas, where at least 13 people have died from heat-related illnesses, according to The Associated Press. Scientists predict that marine heat waves associated with El Niño could devastate fish and coral populations, similar to the 2016 El Niño event, which caused the largest global coral bleaching event on record. 

"The temperature records keep coming," Cobb said. "But it's what they bring with them that really translates into the losses that grabbed my attention."

Facing the combined threats of climate change and El Niño, the world is now more likely than not to breach 1.5 C of temperature rise — the target established under the 2015 Paris Agreement to avoid the worst impacts of climate change — — within the next five years, according to a May report by the World Meteorological Organization. 

"Depending on how large this event gets, [there] obviously could be a really catastrophic pile-on to the year-on-year warming that we know is driven by fossil fuel emissions," Cobb said.

An ancient desert wall in northern Peru was built to protect precious farmlands and canals from the ravages of El Niño floods, according to new research.

Many archaeologists had suggested that the wall, known as the Muralla La Cumbre and located near Trujillo, was built by the Chimú people to protect their lands from invasions by the Incas, with whom they had a long-standing enmity. But the latest research affirms a theory that the earthen wall, which stretches 6 miles (10 kilometers) across the desert, was built to hold back devastating floods during the wettest phases of northern Peru's weather cycle. 

These phases are now known as El Niño — Spanish for "The Boy," a reference to the child Jesus — because they bring heavy rain to the region around Christmastime every few years. 

Although El Niño brings drought to some other parts of the world, it brings heavy rains to Ecuador and northern Peru. El Niño floods are thought to have occurred there for thousands of years, and they would have been a serious danger to the Chimú, Gabriel Prieto, an archaeologist at the University of Florida, told Live Science.

"The annual rainfall there in a regular year is very low — almost no rain at all," he said. "So when the rainfall was very high, that caused a lot of damage."

Related: AI identifies 3 more 'Nazca Lines' figures in Peru

Ancient kingdom

The Chimor kingdom of the Chimú people emerged around A.D. 900 in the territories once occupied by the Moche people; as a result, the Moche period is sometimes called "Early Chimú."

According to the "Encyclopedia of Prehistory" (Springer, 2002) the Chimú worshipped the moon — instead of the sun at the center of Inca worship — and they were independent until they were conquered by the Incas in about 1470, a few decades before the arrival of the Spanish in South America. 

Today, the Chimú are known mainly for their distinctive pottery and metalwork, as well as for the ruins of their capital, Chan Chan, which are listed by the United Nations as a World Heritage site.

Prieto has examined the 8-foot-high (2.5 meters) La Cumbre wall and found layers of flood sediments only on its eastern side, which suggests it was built to protect the Chimú farmlands to the west, beside the coast. Radiocarbon dates from the lowest layers reveal that the wall was started in about 1100, possibly after a large El Niño flood at that time, he said.

The wall is built across two dry riverbeds that flood during El Niño. Preventing flooding in the farmlands also would have protected Chan Chan, which was connected to them by a network of canals. 

"I'd guess, to some degree, that the wall worked like a kind of a dam," Prieto said. The research has not yet been published as a peer-reviewed study.

Human sacrifices

Prieto previously found evidence of mass child sacrifices at Chimú sites, including the remains of 76 victims at Pampa La Cruz near Huanchaco, a few miles northwest of Trujillo. He thinks the El Niño floods that necessitated the desert wall also may have been linked to the sacrifices. 

Prieto has used radiocarbon dating to determine that one of the sediment layers along the wall is from about 1450 — a date that corresponds to the sacrifice of more than 140 children and 200 llamas at another Chimú site. He thinks it's likely that the Chimú knew the dangers of El Niño floods, which happened every few years, and that their society's rulers took advantage of the recurring disaster to solidify their authority with sacrifices.

"The Chimú were the descendants of people who had lived in this region for 10,000 years — they knew exactly what was going on," he said. "This was a kind of political game, I think."

Edward Swenson, an archaeologist at the University of Toronto who isn't involved in the research, told Live Science that Prieto's interpretation made sense.

"The idea at first struck me as incongruous, because I've not heard of walls against water before," he said. 

But Prieto's research has changed his mind, although he still thinks the wall also may have served as a defense. "The old idea was that this wall was to protect the Chimú from Inca attacks, and it might have been multifunctional," Swenson said.

After months of anticipation, the ocean-warming event known as El Niño is officially here and could last until 2024, scientists at the National Oceanic and Atmospheric Administration (NOAA) announced Thursday (June 8).

El Niño events usually occur every two to seven years and are characterized by warmer-than-average sea surface temperatures around the equator in the central and eastern Pacific Ocean. But these events can be felt globally.

"Depending on its strength, El Niño can cause a range of impacts, such as increasing the risk of heavy rainfall and droughts in certain locations around the world," Michelle L'Heureux, a physical scientist at NOAA's Climate Prediction Center, said in a statement. "El Niño could lead to new records for temperatures, particularly in areas that already experience above-average temperatures during El Niño."

Experts have suspected an El Niño this year for some time. A NASA satellite spotted an early sign of El Niño forming in March and April: warm water in the Pacific Ocean moving eastward toward the west coast of South America.

Related: The surface of the ocean is now so hot, it's broken every record since satellite measurements began

Last month, the World Meteorological Organization said that there was a 60% chance that the warming event would strike between May and July and that its likelihood would increase with every passing month. NOAA then released its own forecast, which predicted that an El Niño event was almost guaranteed this year and that it could be a big one. The agency added that there was a 90% chance that the conditions could persist into 2024.

Scientists now expect "moderate-to-strong" conditions lasting into the Northern Hemisphere's fall and winter.

Typically, moderate-to-strong El Niño events mainly affect U.S. weather in the winter, bringing wetter-than-average conditions from Southern California to the Gulf Coast and drier-than-average conditions in the Pacific Northwest and Ohio Valley. This year's event spells warmer temperatures than usual across the northern half of the country.

El Niño also affects the chance of hurricanes, usually helping to suppress hurricane activity in the Atlantic and enhancing it in the central and eastern Pacific basins, according to the statement.

The last El Niño event occurred between February and August 2019, but its impacts were relatively weak.

Average air temperatures tend to be higher in El Niño years than in other years, with far-reaching consequences for global weather patterns. This is compounded by the effects of climate change, which can exacerbate or mitigate certain effects of El Niño, L'Heureux said.

The advent of El Niño this year could help push global temperatures into uncharted territory and contribute to global warming crossing the 1.5-degree-Celsius (1.7 degrees Fahrenheit) threshold within the next five years, which would lead to catastrophic and irreversible climate breakdown.

NASA has identified early signs of El Niño from space, after one of its satellites spotted warm water in the Pacific Ocean moving eastward toward the west coast of South America in March and April. 

Data from the Sentinel-6 Michael Freilich satellite, which monitors sea levels, showed Kelvin waves moving across the Pacific. These long ocean waves are just 2 to 4 inches (5 to 10 centimeters) high but are hundreds of miles wide. They are considered to be a precursor to El Niño when they form at the equator and move the warm upper layer of water to the western Pacific.    

"We’ll be watching this El Niño like a hawk," Josh Willis, a project scientist on Sentinel-6 Michael Freilich at NASA's Jet Propulsion Laboratory (JPL), said in a statement. "If it's a big one, the globe will see record warming."  

How often does El Niño occur?

El Niño is a part of the El Niño-Southern Oscillation (ENSO) climate cycle. Normally, prevailing easterly winds along the equator, known as trade winds, blow surface water west across the Pacific, moving warm water from South America towards Asia. As the warm water moves, cold water rises up to replace it. 

Related: Mysterious, ultra low-frequency noises detected in Earth's atmosphere — and scientists can't explain them

El Niño is linked to weakened trade winds, causing the warm water to be pushed east.

This causes a significant impact on weather patterns around the world. For the U.S., it means wetter weather in the southern parts and hotter weather in northwestern areas.

Its counterpart, La Niña, has the opposite effect, with strong trade winds pushing more warm water west.

El Niño normally hits once every three to five years, but it can occur more or less frequently. The last El Niño was in 2019 and lasted for six months, between February and August.

Is it an El Niño year?

On May 11, National Atmospheric and Oceanic Administration (NOAA) representatives said there was a 90% chance El Niño would hit this year and persist into the Northern Hemisphere's winter. According to NOAA's predictions, there is an 80% chance it will be at least a moderate El Niño — where ocean surface temperatures rise by 1.8 degrees Fahrenheit (1 degree Celsius). 

There is a 55% chance of a strong El Niño, with temperatures rising by 2.7 F (1.5 C), NOAA said. 

A statement from JPL released May 12 said images taken by the Sentinel-6 satellite between the start of March and the end of April show Kelvin waves moving warm water east, pooling it off the coasts of Colombia, Ecuador and Peru. The red and white parts of the animation represent warmer water and higher sea levels.

"Ocean waves slosh heat around the planet, bringing heat and moisture to our coasts and changing our weather," Nadya Vinogradova Shiffer, NASA program scientist and manager for Sentinel-6 Michael Freilich, said in the statement.     

The NOAA and NASA will continue to monitor conditions in the Pacific over the coming months to determine if and when El Niño will hit — and how strong it could be. "Here in the Southwest U.S. we could be looking at another wet winter, right on the heels of the soaking we got last winter," Willis said. 

In April, scientists recorded the highest ever ocean surface temperatures, with the global average reaching 69.98 F (21.1 C). This record reflects the impact of climate change and the last La Niña coming to an end. "Now La Niña is over and the tropical Pacific, which is a huge expansive ocean, is warming up," Michael McPhaden, an oceanographer at the NOAA Pacific Marine Environmental Laboratory, previously told Live Science. 

Willis told Nature the combination of El Niño and supercharged ocean temperatures could mean a "string of record highs" in the next 12 months. “This coming year is gonna be a wild ride if the El Niño really takes off," he said. 

The chance of the ocean-warming event known as El Niño hitting this year is now over 90%. It will likely begin in the coming months, and there is a good chance it will persist into 2024 and have a widespread impact, experts have warned.

El Niño, which means "the little boy" in Spanish, is a major climatic event caused by changes to ocean currents in the Pacific Ocean. This heating event is strong enough to trigger major changes in global weather patterns and seriously impact marine ecosystems, especially combined with the effects of human-caused climate change. El Niño, along with its counterpart La Niña, or "the little girl" — a cooling event triggered by changes to the same ocean current system — make up the El Niño-Southern Oscillation (ENSO) cycle.

Experts have suspected that an El Niño event could be on the horizon for some time. And on May 3, the World Meteorological Organization (WMO) predicted there was a 60% chance that it would begin between May and July. 

But on May 11, the National Atmospheric and Oceanic Administration (NOAA) released its own forecast, which suggested that it is a near certainty that El Niño will begin during the same period. The agency also said there was a 90% chance that El Niño will persist into 2024.

Related: Is climate change making the weather worse?

"Keep your eyes peeled on the tropics, and don’t blink," Nathaniel Johnson, a meteorologist at NOAA's Geophysical Fluid Dynamics Laboratory, wrote in a NOAA blog post. "Conditions are evolving quickly!"

ENSO cycle 101 

The ENSO cycle is mainly linked to trade winds in the Pacific Ocean that blow westward along the equator. Normally, this blows warmer surface waters from South America toward Asia, which are in turn replaced by cooler deep ocean waters in a process known as upwelling, according to NOAA.

During El Niño, the trade winds weaken, which leads to reduced upwelling and in turn warmer surface waters. During La Niña, the trade winds are unusually strong, which has the opposite effect. Both events can trigger extreme weather events, such as the potentially record-breaking Cyclone Freddy that battered parts of Africa in February and March.

The periods between El Niño and La Niña events are known as ENSO neutral.

When was the last El Niño? 

In the past, El Niño and La Niña events occurred roughly once every two to seven years, according to NOAA. But their appearance has recently become much more erratic due to the effects of climate change: In the last 50 years, the ocean has absorbed nearly 90% of the energy trapped by global warming, which has drastically increased sea surface temperatures, impacting the ENSO cycle.

The last El Niño event occurred between February and August 2019 and was quite weak. Between July 2020 and March 2023, a rare triple-dip La Niña suppressed rising global temperatures.

El Niño events normally last somewhere between nine months and two years but can be longer.

How strong will El Niño be? 

It's unclear exactly how strong this El Niño will become, but NOAA's predictions suggest there is an 80% chance of at least a moderate El Niño, where sea surface temperatures will rise by 1.8 degrees Fahrenheit (1 degree Celsius), and a 55% chance of a strong El Niño, where temperatures will rise by 2.7 F (1.5 C).

Experts are also concerned that recent high sea surface temperatures will make the upcoming El Niño worse. In early April, the average global sea surface temperature was the highest in recorded history. 

NOAA will provide more information on how El Niño is progressing in early June.

How will El Niño affect North America? 

During El Niño, the weaker trade winds mean more warm water is pushed back east toward the west coast of the Americas. The warmer waters push the Pacific jet stream south of its neutral position, which impacts weather patterns in North America, according to NOAA. 

For the northern U.S. and Canada, this can lead to warmer weather than usual, while eastern states often receive less rainfall. For the southern U.S. and northern Mexico, the result is often heavy rainfall, which can cause flooding and landslides.

The WMO expects global temperatures to rise to record levels during the next few years as La Niña's cooling effect ends and El Niño begins, which could severely impact the lives of millions of people.

Ocean surface temperatures have hit an all-time high this month, breaking every record since satellite measurements began in the 1980s. 

Temperatures reached a global average of 69.98 Fahrenheit (21.1 degrees Celsius) in the first days of April. The previous record of 69.9 F (21 degrees C) was set in March 2016. Both are more than a degree higher than the global average between 1982 and 2011, which runs at around 68.72 F (20.4 C) in early spring, according to data from the University of Maine Climate Reanalyzer. 

The new record is the result of the buildup of heat from climate change, now unsuppressed by La Niña — a natural ocean cycle of cold surface temperatures in the eastern Pacific that had been ongoing for three years, but which ended in March. 

"Now La Niña is over and the tropical Pacific, which is a huge expansive ocean, is warming up," said Michael McPhaden, an oceanographer at the National Oceanic and Atmospheric Administration (NOAA) Pacific Marine Environmental Laboratory in Seattle. 

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

The background trend across the ocean surface, land surface, and atmosphere, is one of warming, McPhaden said. As greenhouse gases accumulate in the atmosphere, all three heat up. But the trends wobble up and down a bit based on La Niña and El Niño cycles. (During El Niño years, the Pacific surface heats up.) 

"Even though greenhouse gas concentrations in 2022 were the highest ever, it was not the warmest year on record" in terms of global surface temperatures, McPhaden said. That’s because of  La Niña. "Twenty-sixteen was the warmest year on record, and that’s because we had this high burden of greenhouse gas in the atmosphere plus a major El Niño. The combination shot the global surface temps into record territory." 

Some calculations put 2020 as the hottest year on record, while others call it a tie between 2016 and 2020. NOAA's calculations put 2020's average global land and ocean temperatures at 1.76 F (0.98 C) higher than average and only 0.04 F (0.02 C) cooler than 2016.

Currently, the Pacific is in a neutral state of neither El Niño nor La Niña. But forecast models put the chances of tipping into an El Niño later this year at roughly 60%, McPhaden said, which could mean another record-breaking heat year. There is typically a lag between when these oceanic cycles start and when surface temperatures heat up, he said. 

"It’s likely that if we have a big El Niño, we would see a new record set in 2024," he said. 

Still, it's difficult to predict El Niños from early spring trends, McPhaden said, because the oceanic system is volatile this time of year and can easily swing from one pattern to another. 

Climate scientists are still trying to unravel how ocean warming will alter the typical cycle of La Niña and El Niño, he said, but the current consensus is that extremes in both directions will become larger and more frequent. Major El Niños and their accompanying high sea surface temperatures in the Pacific may become twice as common by the end of the 21st century, McPhaden said, which would mean that instead of occurring approximately every 20 years, they might happen every 10. 

The current extremes are already affecting ocean life. Marine heat waves, where ocean temperatures in a particular region rise above the levels that native organisms can tolerate are becoming more common. Particularly vulnerable are corals, which expel the symbiotic single-celled organisms that they host when the water becomes too hot. Corals can survive this process, called bleaching, every once in a while —  but if it happens too often, the corals will die. 

"This is one of the big concerns about rising ocean temps, how it’s going to affect marine ecosystems," McPhaden said. "Coral reef communities have real economic consequences, from the tourism and livelihood of island nations but also protein from the sea. They're a tremendous food source for many nations, and the threats of global warming and pollution and overfishing is a triple whammy." 

After two years of La Niña — El Niño's cooler counterpart — the South Pacific may be facing a potential third appearance of La Niña in a row, which could bring more rainfall to an already-saturated eastern Australia and continue the trend of intense hurricane seasons along the east coast of the United States, and drought conditions in the country's southwestern states. 

This rare occurrence has "only happened twice since 1950," Zoe Gillett, a researcher at the Australia Research Council Centre of Excellence for Climate Extremes, told Live Science. But predicting La Niña is tricky, she warned; climatologists likely won't know which way the winds will blow until September.

If you live in the Northern Hemisphere, you're probably familiar with El Niño, the periodic Pacific Ocean warming event that takes place every few years and shapes global weather patterns. But you might be less familiar with its twin sister, La Niña. Both are part of a climate pattern known as the El Niño-Southern Oscillation (ENSO), which generates variations in weather conditions that last for months.

Related: Hurricane season 2022: How long it lasts and what to expect

El Niño means "the Little Boy" in Spanish; it was so named in the 17th century by fishermen working off the coast of South America. The name was likely a reference to Jesus Christ, as the ocean temperature shift that accompanies El Niño is most noticeable in December, according to the National Oceanic and Atmospheric Administration (NOAA). Indigenous groups in South America almost certainly noticed the phenomenon as well, but their names for it did not survive colonization.

When El Niño conditions are active, sea surface temperatures are above average in the central and eastern tropical Pacific Ocean, according to the National Weather Service. As a result, trade winds across the Pacific weaken and worldwide rainfall patterns shift, bringing, for example, droughts to Indonesia and floods to Peru. This change lasts around nine to 12 months, after which the Pacific either settles back into an "ENSO-neutral" year — in which sea surface temperatures are neither higher nor lower than average — or flips into La Niña.

"La Niña events are essentially the opposite [of El Niño]," Gillett said. La Niña years are characterized by a sustained cooling effect around the equator and eastern tropical region of the Pacific caused by a shift in air pressure systems, according to NOAA’s Pacific Marine Environmental Laboratory. La Niña events bring a more active hurricane season to North America and can lead to heavy flooding in many Pacific Island nations, as well as droughts along South America's west coast.

The ENSO  climate pattern cycles through El Niño and La Niña events about  every three to seven years. However, climatologists did not officially recognize La Niña ("the Little Girl") until the 1980s. While this ENSO pattern is persistent, it is notoriously difficult to predict, especially as it nears a fluctuation point, Science reported.

Unlike El Niño, La Niña can linger for multiple years. Both 2020 and 2021 were La Niña years, and as of right now, the phenomenon has a 52% chance of a three-peat, according to the National Climate Prediction Center. The last triple-dip for La Niña was more than two decades ago, from 1998 to 2001.

Experts say that escalating climate change will likely impact the intensity (though not necessarily the frequency) of future El Niño and La Niña events. "We should expect almost double the number of extreme La Niña events compared to last century," Gillett said. "However, we do have to interpret these climate models with care."

Originally published on Live Science.

North Pacific loggerhead sea turtles (Caretta caretta) hatch on the shores of Japan and spend much of their time in the open Pacific, but sometimes mysteriously crop up in Mexico, 9,000 miles (14,500 kilometers) away from their original nesting ground.

That incredible journey requires them to pass through potentially deadly, cold waters that should be inhospitable to them, since loggerheads rely on warmth from the surrounding environment to maintain their core body temperatures. Now, scientists have a clue as to how the turtles survive this epic migration.

"This mystery had been around for decades, and nobody had a clue how to explain it," said senior author Larry Crowder, a professor of marine ecology and conservation at Stanford University's Hopkins Marine Station and a senior fellow at the Stanford Woods Institute for the Environment.

Along the North American Pacific coast, seasonal winds from the north periodically sweep down the shoreline, pushing warm surface waters offshore. Cold water from the deep ocean then rises up to replace that warm water, dragging up an abundance of nutrients with it. Tropical animals, including loggerheads, rarely venture into these cold waters from the open Pacific, Crowder said. Charles Darwin even described the region as "impassable" for warm-water-loving critters, he added. 

Related: Top 10 most incredible animal journeys 

But according to the new study, published April 8 in the journal Frontiers in Marine Science, loggerheads may have a fleeting opportunity to reach the Mexican coast during El Niño, a climate cycle that shifts warm water in the western tropical Pacific Ocean eastward along the equator.

"A warm 'door' needs to open for these turtles to get to Mexico," Crowder told Live Science. The study authors refer to this temporary door as a "thermal corridor" — essentially a passageway of warm water. "During El Niño, the turtles get a shot at going across." 

This study not only sheds light on a long-standing mystery but could also provide critical information for protecting loggerheads, which are considered "vulnerable" by the International Union for Conservation of Nature (IUCN). Conservation efforts may need to adapt as the turtles react to warming waters, driven by climate change, Crowder said. 

"With climate change comes increasingly warmer sea surface temperatures and longer periods of warm water events in the Pacific Ocean," said Carolyn Kurle, an associate professor of biological science at the University of California, San Diego, who was not involved in the study.

If the thermal corridor hypothesis is true, more loggerhead juveniles may migrate to the North American coast over time, Kurle told Live Science in an email. This could be beneficial to young turtles, since the ample nutrients in these coastal waters boost the turtles' food supply, she said. "But it would be terrible" if more young turtles accidentally became ensnared in fishing nets along the coast, especially since those turtles would not have the chance to return to Japan and mate, Kurle told Live Science. 

A decades-long mystery 

Loggerheads can be found all over the world, primarily in subtropical and temperate waters, and are divided into nine subpopulations, including the North Pacific subpopulation, according to the National Oceanic and Atmospheric Administration (NOAA). Scientists first got a clue that North Pacific loggerheads migrate between Mexico and Japan when Adelita, a female turtle, was released from captivity in Baja California in 1996 and immediately made a beeline for East Asia, Crowder said. 

Marine biologist Wallace Nichols had attached a satellite-tag to Adelita, so he was able to track her entire journey to Japan, according to PBS. Crowder and his co-authors used similar tracking data for their new study, but they pulled from an enormous dataset of 231 juvenile loggerheads whose migratory patterns had been monitored for 15 years.

About 97% of these loggerheads remained in the open ocean and did not venture toward the North American coast. In fact, when these turtles did near the edge of the coastal ecosystem, they promptly turned around. Dana Briscoe, a postdoctoral researcher in Crowder's lab at the time, found that the timing of the turnaround appeared to be driven by Earth's magnetic field, which the turtles can sense and use to navigate through the ocean. Presumably this ability helps them avoid cold water, Crowder said.

However, Briscoe noticed that not all the turtles turned around at the typical point — six of the 231 turtles just continued on their merry way and swam right into coastal waters, entering an area known as the California Current Large Marine Ecosystem (CCLME). The team looked closer at these six outliers and found that they each made their journey in the spring, and based on data gathered from remote sensors, these wandering turtles "experienced unusually warm conditions," compared with their counterparts.

"And the two that made it closest to Baja experienced the warmest water conditions," Crowder said. Seeing this connection to warm water, the team developed their thermal corridor hypothesis.

Related: The reality of climate change: 10 myths busted

But because only six turtles out of 231 — roughly 3% — entered the CCLME, the team needed more data to back up their idea. So they teamed up with Calandra Turner Tomaszewicz, a scientist at the NOAA Southwest Fisheries Science Center, whose group had been studying the bones of turtles that had stranded in Mexico and died on the shore. 

Sea turtle bones contain annual growth rings, similar to trees. A new ring grows around the outside of the bone each year, while one ring erodes from the center of the bone. A turtle's humerus bone, a type of leg bone, has about six to eight growth rings at any given time, Crowder said. 

These growth rings contain clues about what a turtle ate in a given year, in the form of stable isotopes, which are chemical elements with different numbers of neutrons. Provided a scientist knows when the turtle died, they can use these chemical clues to determine what the turtle ate throughout its life, and therefore, where that turtle was likely located. 

"And the stable isotope ratios in open ocean-food, like jellyfishes, is dramatically different than in crabs," which is what a loggerhead would eat in coastal waters, Crowder said. In this way, the team determined when a given turtle made the jump from open to coastal waters. They then looked up water temperatures in that year.

Turner Tomaszewicz and her colleagues analyzed the growth rings of 33 loggerheads in Mexico and found that more than 60% of the turtles entered the region near the shore in a year with warm ocean conditions. Grouping the turtles by year revealed that far more turtles arrived in Mexico in the warm years than cool ones.

"The bone growth layer analyses absolutely strengthened their thermal corridor hypothesis," supporting the idea that these transient passages of warm water help more turtles reach the North American coast, Kurle said. 

The hypothesis might also explain why loggerhead turtles from Japan cropped up in San Diego Bay in 2016, an El Niño year, Crowder said. The turtles only rarely show up in southern California, and even then, they don't usually appear in large groups, as they did that year, according to The San Diego Union-Tribune. The strange event led some scientists to wonder whether, with climate change, loggerheads might come to San Diego more often.

Of course, the thermal corridor hypothesis is still just that — a hypothesis. Ideally, the team would be able to satellite-tag more loggerheads, track their movements and see how many migrate to Mexico in El Niño years, compared with cool La Niña years , Kurle said. However, seeing that so few turtles seem to enter the CCLME, this effort would likely be expensive and impractical, Crowder said. Instead, he said he hopes to conduct an experimental study with a few dozen turtles, where two groups of loggerheads would be released into the open ocean near the CCLME boundary, one in a El Niño year, and one in a La Niña year.

But for now, even with its limited data, the current study "will help those who seek to understand and manage this vulnerable species with one of the longest migrations in the animal kingdom," Kurle told Live Science.

Originally published on Live Science. 

A climate pattern known as La Niña is emerging in the equatorial Pacific Ocean, supporting climate scientists' predictions for an active Atlantic hurricane season. La Niña could also bring warmer, drier conditions to southern states in the U.S. — many of which are already experiencing extreme drought.

La Niña ("The Girl" in Spanish) and its counterpart El Niño ("The Boy") are part of a climate pattern known as the El Niño Southern Oscillation (ENSO), which affects sea-surface temperatures in the central and eastern Pacific Ocean, close to the equator. During a La Niña cycle, waters in that ocean region are cooler than average.

El Niño conditions — warmer-than-average waters in the equatorial Pacific — help to suppress hurricane formation in the Atlantic Ocean. La Niña does the opposite; under La Niña, cooler Pacific waters weaken wind shear over the tropical Atlantic Basin and the Caribbean Sea, enabling more hurricanes to take shape, scientists with the National Oceanic and Atmospheric Administration (NOAA) said in a statement released on Sept. 10. 

Related: A history of destruction: 8 great hurricanes

There is a 75% chance that La Niña's cooler-than-average sea-surface temperatures will persist from December 2020 through February 2021, according to the statement. La Niña conditions last appeared during the winter months of 2017 through 2018, with El Niño developing in 2018 through 2019. 

A third part of the ENSO cycle — when ocean waters are neither warmer nor colder than average, sometimes called "La Nada" ("The Nothing" in Spanish) — is neutral, and does not significantly influence global climate patterns, NOAA says.

La Niña's presence over the winter months will also be felt across the U.S.; the climate pattern brings cooler, wetter conditions to northern states, while southern states will be warmer and have less precipitation than they normally do, according to NOAA.

In August, NOAA experts predicted that the 2020 hurricane season would be one of the busiest on record. One of the factors behind that prediction was growing evidence that ocean conditions were trending toward La Niña; though La Niña doesn't actively fuel hurricanes, it doesn't suppress their formation like El Niño does, Live Science previously reported.

"Overall, the coupled ocean-atmosphere system was consistent with La Niña conditions," researchers with the National Weather Service's Climate Prediction Center said yesterday (Sept. 10) in a statement.

NOAA's August outlook predicted a hurricane season with an 85% chance of above-normal activity, capable of producing up to 25 named storms — the highest number ever predicted — with winds of at least 39 mph (63 km/h).

Indeed, hurricane season began early this year, with the first named storm, Arthur, forming on May 17 (the "official" start of Atlantic hurricane season is June 1). Nine named storms emerged by the end of July. The 12th storm, Hurricane Laura, barreled into coastal Louisiana on Aug. 27 as a Category 4 storm, with winds topping 150 mph (240 km/h) and a storm surge described by the National Hurricane Center as "unsurvivable," Live Science reported. It was the strongest hurricane to strike the Gulf Coast since 2005's Hurricane Katrina. 

Other factors are also driving this year's unusually active hurricane season, including an enhanced West African monsoon; weaker trade winds in the tropical Atlantic Ocean; and warmer-than-average sea-surface temperatures in the Caribbean Sea and in the tropical Atlantic, NOAA scientists reported in August. 

These conditions, which have persisted for decades, are thought to be responsible for more active hurricane seasons overall, dating from 1995. What's more, they show no signs of dissipating, hinting that highly active hurricane seasons will be more frequent in the years to come, NOAA's lead hurricane season forecaster Gerry Bell said in August.

"We're not seeing an end to this era," Bell said. "We're 26 years into it, and we don't know how long it's going to last."

Originally published on Live Science.

Scientists are predicting a near-normal Atlantic hurricane season this year, with two to four major hurricanes reaching at least Category 3 status, with winds of 111 mph (178 km/h) or higher, the National Oceanic and Atmospheric Administration (NOAA) announced today (May 23).

But this "near-normal" description doesn't mean people in the U.S. Southeast and Eastern Seaboard can rest easy.

"That's a lot of activity," Gerry Bell, the lead hurricane season forecaster with NOAA's Climate Prediction Center, told reporters at a news conference today. "You need to start getting ready for the hurricane season now." [The 20 Costliest, Most Destructive Hurricanes to Hit the US]

The 2019 Atlantic hurricane season — which lasts from June 1 to Nov. 30 — is expected to have between nine and 15 named storms, which means they pack winds of 39 mph (62 kilometers/hour) or higher, NOAA reported. Of those, between four and eight could become hurricanes, meaning their winds reach speeds of 74 mph (119 km/h) or higher.

Although just four of these hurricanes may top Category 3 status, "it only takes one land-falling hurricane to cause great destruction to a community," Daniel Kaniewski, the acting deputy administrator at the Federal Emergency Management Agency (FEMA) told reporters.

During an average hurricane season, the Atlantic sees about 12 named storms, including six hurricanes and three major hurricanes. Last year's season was above average, with 15 named storms, including eight hurricanes, of which two were major — the destructive hurricanes Michael and Florence.

However, it's impossible to know whether any of the storms or hurricanes predicted for the 2019 season will make landfall, said Neil Jacobs, acting NOAA administrator.

The officials added that this year marks the first time NOAA's fleet of Earth-observing satellites, including three operational next-generation satellites, were used to gather data for the hurricane forecast models. This data also helped NOAA issue a storm prediction for the eastern and central Pacific basins. According to NOAA, the Pacific should expect an above-normal season with 15 to 22 named storms, of which eight to 13 are expected to become cyclones (the term given to "hurricanes" in these parts of the Pacific). Of these, between four and eight could be major cyclones, NOAA reported.

What forces are involved?

A near-normal Atlantic hurricane season may sound surprising, given that there is an ongoing El Niño this year — a climate phenomenon known for warming waters in the equatorial Pacific Ocean that can impact weather worldwide. El Niño also acts to increase wind shear in the Atlantic, which disrupts the flow of heat and moisture, ingredients needed for hurricanes to form.

In other words, El Niño often suppresses hurricane activity in the Atlantic, Bell said.

But this year's El Niño is weak, and it's competing with the other climate factors. These hurricane-favoring factors are warmer-than-average sea-surface temperatures in the tropical Atlantic Ocean and Caribbean Sea (a pattern seen since 1995) and a strong monsoon in West Africa, Bell said. "They favor more activity," Bell said.

What to do

People in hurricane-prone areas should make emergency plans now, Kaniewski said. This includes getting enough supplies — such as food, water and medicine — to last at least 72 hours, he said. In the event of a powerful storm or hurricane, people should also expect major communication networks to go down, so they should have a battery-powered radio to stay updated and have an emergency evacuation route in mind, he added.

Kaniewski also encouraged people to have cash on hand, in case the electricity goes out and ATMs and credit card swipe machines fail, as well as homeowners' and flood insurance. To learn more, download the free FEMA application, which provides a number of services, including weather alerts, lists of open shelters and advice on emergency preparedness.

• Hurricanes from Above: Images of Nature's Biggest Storms
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• Inside Irma's Eye: Hurricane Hunters Capture Jaw-Dropping Photos

Originally published on Live Science.

The largest child sacrifice on record took place after a torrential rainfall, when about 140 children and 200 young llamas likely had their hearts ripped out by the ancient Chimú culture in A.D. 1450, in what is now Peru.

The reason for the sacrifice, however, remains a mystery, according to a new study. Even so, the scientists of the study have several ideas.

For instance, heavy rainfall and flooding from that year's El Niño weather pattern may have prompted Chimú leaders to order the sacrifice, but without more evidence, we'll likely never know the real reason, said study co-researcher John Verano, a professor in the Department of Anthropology at Tulane University in New Orleans. [25 Cultures That Practiced Human Sacrifice]

Study lead researcher Gabriel Prieto, an assistant professor in archaeology at the National University of Trujillo, Peru, learned about the sacrificial site in 2011, after a father approached him while he was doing fieldwork on another project. The father described a nearby dune with bones poking out of it. The father said, "Look, my kids are bringing bones back every day, and I'm tired of it," said Verano, who later joined the project in 2014.

Once at the dune, Prieto immediately realized that the site had archaeological significance, and he and his colleagues have been working on it since, excavating and studying the human and llama (Lama glama) remains at the site, know as known as Huanchaquito-Las Llamas.

"It's the largest child sacrifice event in the archaeological record anywhere in the world," Verano said. "And it's the largest sacrifice with llamas in South America. There's nothing like this anywhere else."

Who were the victims?

The site holds the remains of at least 137 boys and girls and 200 llamas. Many of the children and the llamas had cut marks on their sterna, or breastbones, as well as displaced ribs, suggesting that their chests had been cut open, perhaps to extract the heart, the researchers wrote in the study.

The children ranged in age from 5 to 14 and were generally in good health, according to an analysis of their bones and teeth. These youngsters were wrapped in cotton shrouds and buried either on their backs with extended legs, on their backs with flexed legs or and resting on one side with flexed legs. Many were buried in groups of three and placed from youngest to oldest.

Some had red cinnabar paint (a natural form of mercury) on their faces, and others, especially the older children, wore cotton headdresses. The llamas were either laid next to or on top of the children's bodies. In many cases, llamas of different colors (brown and beige) were buried together, but facing different directions.

Also buried at the site, near the children's remains, were the bodies of two women and a man. These adults do not have cut marks on their sterna, suggesting their hearts weren’t removed. Rather, one woman likely died from a blow to the back of the head and another suffered from blunt force trauma to her face. The man had rib fractures, but it wasn't clear whether these injuries happened before or after death, possibly due to the weight of the rocks that were placed over his body, the researchers said. [Photos: Hundreds of Mummies Found in Peru]

The children weren't buried with any discernible offerings, but the researchers did find a pair of ceramic jars and wooden paddles on the edge of the site, next to a single llama.

What happened?

The Chimú culture dominated a large part of the Peruvian coast from the 11th to 15th century. It thrived, in part, because of its intensive agriculture; the Chimú watered their crops and livestock with a sophisticated web of hydraulic canals, the researchers wrote in the study.

This area is typically dry, drizzling only a few times a year. But it's possible an extreme El Niño event, when warm water evaporates from the southern Pacific and falls as torrential rain on Peru's coast, caused havoc in the society, not only flooding the Chimú's lands but also driving away or killing marine life off the coast, Verano said.

Evidence shows that when the children and llamas were sacrificed, the area was sodden with water, even capturing human and animal footprints in the muck that still exist today. It's unclear why this particular site, located almost 1,150 feet (350 meters) from the coast about 2 miles (3.2 kilometers) north of the city of Chan Chan, was chosen for the sacrifice, but researchers have some idea for why the children were chosen.

Children are often seen as innocent beings who aren't yet full members of society, and thus might be viewed as appropriate gifts or messengers to the gods, Verano said.

Moreover, these children were not all locals. Some of the children had experienced head shaping, and an analysis of carbon and nitrogen isotopes (an isotope is a variation of an element) in their remains showed that these kids came from different regions and ethnic groups within the Chimú state, the researchers found.

It's unclear why their hearts were removed, but "worldwide, everyone is aware that the heart is a very dynamic organ," Verano said. "You can feel and hear it beating. It's very vital. If you take the heart out, a lot of blood comes out and the person dies."

Today, some people in the Peruvian highlands and Bolivia still remove the hearts from sacrificed llamas, Verano noted. Sometimes the removed heart is burned and the animal’s blood gets splashed on places like mines, a measure thought to protect the workers within. However, it's unknown how the Chimú viewed and treated hearts in antiquity, Verano said. [Photos: Ancient Circular Geoglyphs Etched into the Sand in Peru]

The children's remains are now safely stored by Peru's Ministry of Culture, and the researchers have submitted permits so they can continue to study them, Verano said.

The discovery shows "the importance of preserving cultural patrimony and archaeological material," Verano said. "If we had had not dug this, it would probably be destroyed now by housing and urban expansion. So we've saved a little chapter of prehistory."

The study is "an incredible insight into the ritual and sacrificial practices of the Chimú kingdom," said Ryan Williams, a curator, professor and head of anthropology at The Field Museum in Chicago, who has worked as a South American archaeologist for more than 25 years.

He added that while human sacrifice is reviled in our modern society, "we have to remember that the Chimú had a very different world view than Westerners today. They also had very different concepts about death and the role each person plays in the cosmos," Williams, who was not involved with the study, told Live Science in an email.

Given that the sacrifice may have been in response to devastating floods, "perhaps the victims went willingly as messengers to their gods, or perhaps Chimú society believed this was the only way to save more people from destruction," Williams said.

The study was published online today (March 6) in the journal PLOS ONE.

• 7 Bizarre Ancient Cultures That History Forgot
• Photos: The Amazing Mummies of Peru and Egypt
• Photos: Mummy Hair Reveals Ancient Last Meals

Originally published on Live Science.

Evidence is mounting against the so-called climate change hiatus — a period lasting from 1998 to 2012 — when global temperatures allegedly stopped rising as sharply as they had before. This misconception can be explained, in part, by missing temperature data from the Arctic, a new study finds.

That seeming pause in rising global temperatures had been used as evidence by climate skeptics to suggest that the Earth wasn't really warming at an unnatural pace.

To get around the data gap, researchers from the University of Alaska Fairbanks (UAF) and China created the first global data set of surface temperatures. They filled in the missing puzzle piece with data taken from buoys drifting in the Arctic Ocean during the so-called global warming hiatus, the researchers said. [6 Unexpected Effects of Climate Change]

"We recalculated the average global temperatures from 1998 to 2012 and found that the rate of global warming had continued to rise at 0.112 degrees Celsius [0.2 degrees Fahrenheit] per decade, instead of slowing down to 0.05 degrees C [0.09 degrees F] per decade as previously thought," study co-researcher Xiangdong Zhang, an atmospheric scientist with UAF's International Arctic Research Center, said in a statement.

The new estimates reveal that the Arctic heated up rapidly during this period — more than six times the global average, said Zhang, who is also a professor with UAF's College of Natural Science and Mathematics.

Mind the gap

The reason for the data gap is simple: The remote Arctic doesn't have a robust network of instruments that collect air temperature data, the researchers said.

To fill in the gap, the team used temperature data collected from the University of Washington's International Arctic Buoy Programme, which allowed them to reconstruct Arctic surface air temperatures from 1900 to 2014, the researchers wrote in the study. The researchers also used newly corrected worldwide sea-surface temperature data from the National Oceanic and Atmospheric Administration. (Government temperature datasets are corrected, that is, vetted, before their official release, Live Science previously reported.)

The researchers incorporated the Arctic information with the global data. Then, they re-estimated average global temperatures from 1998 to 2012 with more accurate and representative data, Zhang said.

The hiatus

The hiatus is a controversial topic among climate scientists. At the time and following the hiatus, many researchers acknowledged that temperature data indicated that the Earth was still warming, but not as rapidly as it had prior to that 14-year stint. Climate change doubters seized on these findings, using the pause as evidence to show that man-made climate change wasn't real, Live Science previously reported.

Over the past century, Earth's average temperature has increased as human-made technologies emitted more greenhouse gases, such as carbon dioxide, that linger in the atmosphere and trap heat.

That's why the so-called global-warming hiatus confounded scientists. Some researchers suggested that the unusually warm 1997 to 1998 El Niño, and a long period afterward without an El Nino in the tropical Pacific Ocean might have diminished the rate of global warming.

However, the new findings show that this pause didn't happen after all, the researchers said. Moreover, the study shows that Arctic temperature data is key when calculating climate change. Until recently, many scientists didn't think that the Arctic was large enough to greatly influence average global temperatures, Zhang said.

"The Arctic is remote only in terms of physical distance," he said. "In terms of science, it's close to every one of us. It's a necessary part of the equation and the answer affects us all."

Another 2017 study, published in the journal Science Advances, also recently cast doubt on the so-called hiatus. That study showed that inconsistent water measurements helped lead to the hiatus misconception, Live Science reported.

The new study was published online Monday (Nov. 20) in the journal Nature Climate Change.

Original article on Live Science.

The hurricane season is likely to be extra active this year, thanks to a likely no-show from El Niño.

The National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center released an updated hurricane season outlook today (Aug. 9). The new prediction ups the odds for a blustery, extremely active hurricane season – and possibly even the most active since 2010.

"We're now entering the peak of the season, when the bulk of the storms usually form," Gerry Bell, the lead seasonal hurricane forecaster at NOAA's Climate Prediction Center, said in a statement. "The wind and air patterns in the area of the tropical Atlantic and Caribbean where many storms develop are very conducive to an above-normal season. This is, in part, because the chance of El Niño forming, which tends to prevent storms from strengthening, has dropped significantly from May." (El Niño is a climate phenomenon most distinguished by the shift of warm water from the western to the central and eastern tropical Pacific Ocean.) 

One other factor fueling a more active hurricane season: The waters off the tropical Atlantic Ocean are warmer than usual.

The new forecast puts the odds of an above-average season at 60 percent, up from the initial forecast of 45 percent in May. In addition, the forecast now predicts between 14 and 19 named storms, or those with sustained winds of 39 mph (62 km/h),  and between two and five major hurricanes with sustained windspeeds of at least 111 mph (178 km/h).

The NOAA center typically puts out an initial hurricane forecast in late May. This year, they initially predicted between 11 and 17 named storms and between two and four major hurricanes, and about even odds for an average and above-average season.

So far, the season has already had six named storms, double what's typically expected by this point. (The storms were Arlene, Bret, Cindy, Don, Emily, Franklin and Gert). Typically, it takes six months to rack up that many storms; an average season has 12 major storms, six of which become hurricanes and three of which are major hurricanes. Hurricane season typically lasts from June 1 to Nov. 30.

Originally published on Live Science.

The year 2016 was one for the record books, at least when it comes to the weather. Last year had the highest global temperature in modern history and extremely high levels of carbon dioxide and sea level rise, as well as exceptionally low levels of Arctic sea ice, according to the United Nation's World Meteorological Organization (WMO).

These alarming weather events and trends are continuing into 2017, the WMO said in a report released Tuesday (March 21).

The report — part of the WMO's annual State of the Global Climate — pulled data from multiple international datasets that are independently maintained. In addition, for the first time in its more than 20-year history of issuing these statements, the WMO partnered with other United Nations branches to include data on social and economic impacts of climate change. [The Year in Climate Change: 2016's Most Depressing Stories]

"This report confirms that the year 2016 was the warmest on record — a remarkable 1.1 degrees Celsius [1.98 degrees Fahrenheit] above the pre-industrial period, which is 0.06 C [0.1 F] above the previous record set in 2015," Petteri Taalas, the WMO secretary-general, said in a statement. "This increase in global temperature is consistent with other changes occurring in the climate system."

For instance, globally averaged sea-surface temperatures also experienced record-breaking highs, Taalas said.

"With levels of carbon dioxide in the atmosphere consistently breaking new records, the influence of human activities on the climate system has become more and more evident," Taalas said. Scientists are able to connect these high temperatures and some extreme weather events to man-made climate change by using long-term climate data and high-powered computing tools, he added.

Some of 2016's extreme weather events include severe droughts that caused food insecurity among millions of people in southern and eastern Africa and Central America; Hurricane Matthew, which carved a destructive trail through Haiti in October 2016 and was the first Category 4 storm to make landfall there since 1963; and heavy rains and floods in eastern and southern Asia, according to the WMO.

Mercury rising

Each of the 16 years since 2001 has been at least 0.72 F (0.4 C) warmer than the long-term average for the 1961-1990 base period, the WMO said. Every decade, temperatures have warmed 0.18 F to 0.36 F (0.1 to 0.2 C), the organization added.

The El Niño of 2015 and 2016 explains, in part, why 2016 was so hot. On top of warming long-term climate change temperatures, the weather is usually warmer during strong El Niño years, including 1973, 1983 and 1998 — years that had temperatures between 0.18 F and 0.36 F warmer than background levels.

During El Niño periods, warm water in the western tropical Pacific Ocean flows eastward toward South America, and heats surface waters off the coast of northwestern South America. These warm waters evaporate easily, and can fuel Pacific hurricanes and other unusual weather events. The temperatures of 2016 were consistent with this pattern, the WMO said.

Sea levels worldwide also rose so much during the recent El Niño event that early 2016 levels broke record highs. Meanwhile, global sea ice cover recededmore than 1.5 million square miles (4 million square kilometers) below average in November.

Higher ocean temperatures have contributed to coral bleaching and mortality, even in tropical waters. When coral die, the entire marine food chain is harmed, the WMO said.

In addition, atmospheric carbon dioxide (CO2) levels reached 400 parts per million (ppm) in 2015, the WMO said. That figure means there were 400 molecules of carbon dioxide in the air per every million air molecules. The 400 ppm threshold is high in contrast with the past 800,000 years, when CO2 levels fluctuated between about 170 ppm and 280 ppm, Michael Sandstrom, a doctoral student in paleoclimate at Columbia University in New York City, previously told Live Science.

The Paris Agreement, a U.N. climate treaty, addresses how to countries can decrease their emissions of CO2 and other greenhouse gases. The agreement is vital as it encourages the world to tackle "climate change by curbing greenhouse gases, fostering climate resilience and mainstreaming climate adaptation into national development policies," Taalas said. [Earth in the Balance: 7 Crucial Tipping Points]

2017 trends

Not everything made it into the 2016 report. New studies show that the ocean heat content may have increased more than previously thought, and early data suggests that there is no easing in the rate of increase for atmospheric CO2 concentrations, the WMO said.

"Even without a strong El Niño in 2017, we are seeing other remarkable changes across the planet that are challenging the limits of our understanding of the climate system," David Carlson, the World Climate Research program director, said in the statement. "We are now in truly uncharted territory."

For instance, the Arctic has had three "polar heat waves" this winter, Carlson said. These heat waves are alarming because sea ice, which usually refreezes during Arctic winters, is already at record lows compared with the past few years, he said.

What's more, changes in the Arctic and melting sea ice are causing a shift in wider oceanic and atmospheric circulation patterns, the WMO said. These changes are affecting the jet stream, the fast-moving band of air that regulates worldwide temperatures, and are already influencing weather patterns around the planet, the WMO said.

For example, parts of Canada and the United States were unusually balmy this year, while other regions, including the Arabian Peninsula and northern Africa, were unseasonably cold in early 2017.

In South Africa, the city of Pretoria sizzled at 108.8 F (42.7 C) and Johannesburg reached 102 F (38.9 C) on Jan. 7 — temperatures that were at least 5.4 F (3 C) higher than previous all-time records for those sites, the WMO said.

In February, the United States broke or tied more than 11,700 warm temperature records, the U.S. National Oceanic and Atmospheric Administration said. Down Under, where the seasons are flipped, parts of Australia had prolonged and extreme heat in January and February, and broke many new temperature records, the WMO said.

Original article on Live Science.

When Hurricane Nicole formed in the Atlantic Ocean right on the heels of Hurricane Matthew, which tore across Haiti and the Bahamas last week before lashing the southeastern United States, it was the first time on record that two major Atlantic hurricanes have occurred in the month of October. But these rare, back-to-back hurricanes may be an early sign of worse weather to come if La Niña climate conditions take hold across the globe, according to weather scientists.

Hurricane Nicole battered Bermuda yesterday afternoon (Oct. 13) with torrential rain and winds of up to 130 miles per hour (209 km/h), causing widespread property damage and leaving thousands of homes without power. The storm is now moving northeast across the Atlantic, away from Bermuda, and is expected to become a post-tropical cyclone tomorrow (Oct. 15), according to an advisory posted today (Oct. 14) at 11 a.m. ET (1500 GMT) by the National Hurricane Center (NHC).  

It was the second major hurricane to make landfall in the western Atlantic within five days, and the first time that two major hurricanes of Category 4 or Category 5 have formed in the Atlantic in October since record keeping began in 1851. [See Photos of the Tropical Storms and Hurricanes of 2016]

On Oct. 4, as Nicole strengthened over the ocean and Matthew made landfall in Haiti, the storms were the first large hurricanes — above Category 2 — to occur at the same time in the western Atlantic since 1964, according to the NHC.

The twin hurricanes may herald a much stormier time in the Atlantic, after a few years of relatively low hurricane activity, said Kevin Walsh, a professor of tropical meteorology at Australia’s University of Melbourne, who has watched the development of Matthew and Nicole over recent weeks. 

"We know during El Niño years in the Atlantic you get usually suppressed numbers of tropical cyclones — and of course El Niño is all over now, and we may or may not be moving into a mild La Niña," Walsh told Live Science. "But, if a big La Niña does actually set in, then it's quite possible that we could have increased hurricane numbers in the Atlantic."

The return of La Niña

El Niño and La Niña are the opposite phases of the El Niño Southern Oscillation (ENSO) cycle, caused by fluctuations in temperature between the ocean and the atmosphere in the tropical zones of the central and eastern Pacific Ocean, according to the National Oceanic and Atmospheric Administration (NOAA).

Each phase of the ENSO cycle can have different effects on the climate in different parts of the world. They usually last from nine months to a year, but some persist for several years, like the latest El Niño phase from 2011 to 2015, NOAA said.

If the oceans and atmosphere over the Pacific Ocean are now entering a prolonged La Niña phase, then hurricanes in the Atlantic Ocean are likely to become more common the longer it lasts, Walsh said.

"The only thing that it really depends on is how long the La Niña hangs around — and we don't know that at present, so it's a bit soon to be trying to predict for the Atlantic next year," he added. [A History of Destruction: 8 Great Hurricanes]

Tropical Storm Matthew first formed in a relatively normal way off the African coast in late September. The storm gained strength as it tracked across the Atlantic toward the Caribbean, where it rapidly intensified into a Category 5 hurricane on Sept. 30.

But Tropical Storm Nicole took a strange route across the Atlantic Ocean after it formed in early October, and meteorologists predicted more than once that the storm could disappear entirely.

"It is a bit unusual, partly because it's done a sort of funny loop-de-loop in the middle of nowhere, and then become quite strong after that," Walsh said.

Growing a hurricane

The way Hurricane Nicole lingered over the Atlantic likely increased its chances of becoming a stronger hurricane, Walsh said.

For example, the storm may have intensified after running into an area of very warm sea temperatures, or when atmospheric conditions turned more favorable for hurricane formation, he added.

Walsh also noted that an uncommon number of major hurricanes have hit Bermuda in recent years, although the region often endures several tropical storms each year.

"It's pretty rare for a hurricane to strike Bermuda directly, but that's happened a lot in the last few years," he said.

Only seven major hurricanes have passed within 40 nautical miles (74 km) of Bermuda since record- keeping began in 1851, but in 2014, the islands were hit by two hurricanes only six days apart: Hurricane Fay on Oct. 12, and Hurricane Gonzalo on Oct. 18.

Hurricane Fay was a Category 1 storm when it made landfall, and Gonzalo had weakened from a Category 4 storm to a Category 2 before it struck the island, but the combined effect of the two hurricanes just days apart resulted in heavy damage and disruption.

For now, the National Hurricane Center reports no "imminent tropical threats" in the Atlantic basin: no tropical storms or depressions that show the potential to develop into a hurricane.

But more than a month remains before the official end of this year's Atlantic hurricane season, on Nov. 30 — and until then, scientists and storm watchers will be keeping a keen eye on the tropics.

Original article on Live Science.

Australia's Great Barrier Reef corals are in trouble.

The northern part of the world's largest coral reef ecosystem is experiencing "the worst mass bleaching event in its history," according to a statement released Tuesday (March 29) by the Australian Research Council.

Documented by the National Coral Bleaching Taskforce (NCBT) in aerial surveys, observations of more than 500 coral reefs spanning 2,485 miles (4,000 kilometers) showed that the majority of reefs were undergoing extensive and severe bleaching.

"Almost without exception, every reef we flew across showed consistently high levels of bleaching, from the reef slope right up onto the top of the reef," said Terry Hughes of the NCBT, calling the surveys "the saddest research trip of my life." [Worst Coral Reef Bleaching on Record for the Great Barrier Reef | Aerial Video]

Bleaching happens when corals are exposed to stresses such as warmer-than-average waters for prolonged periods of time. The corals respond to the stress by expelling the algae that provide them with their color, which makes the corals look like they've been bleached white. Bleaching can be fatal for corals if the stress is too intense, or if it continues for too long and the algae are unable to recolonize them.

Ecosystem at risk

Australia's Great Barrier Reef (GBR) covers 134,364 square miles (348,000 square kilometers), making it larger than the U.K., Switzerland and the Netherlands combined, according to the Great Barrier Reef Marine Park Authority. Recognized as a World Heritage Area in 1981, the reef contains 400 types of coral and hosts 1,500 types of fish and 4,000 mollusk species, as well as other marine life such as large green turtles and dugongs ("sea cows").

The GBR experienced bleaching events in 1998 and in 2002, but the current mass bleaching is much more severe, experts are saying. Rebecca Albright, a marine biologist with the Carnegie Institution for Science in Washington, D.C., has studied the GBR since 2011. Albright told Live Science that 95 percent of the GBR's northern reefs are currently showing signs of extreme bleaching, compared with 18 percent that experienced bleaching in 2002.

Even the more robust corals are affected, Albright said, another sign that this event is particularly serious. She cautioned that it's still too early to assess the long-term impacts of bleaching on the corals, though estimates of coral mortality anticipate losses of about 50 percent.

Two factors are responsible for stressing the corals, Albright said: climate change, which is driving ocean temperatures upward, and a strong El Niño  — a cyclical climate event associated with warmer-than-average sea surface temperatures in the tropical Pacific. And with El Niño conditions expected to extend through 2016, that doesn't bode well for the corals' recovery.

"Corals are sensitive to not only the anomaly in temperature — how high it goes — but also the duration of that exposure," Albright told Live Science. "This kind of perfect storm of all these factors coming together makes this a catastrophic scenario right now." [Images: Colorful Corals of the Deep Barrier Reef]

A global event

But what's happening to the GBR is only part of the picture. A global bleaching event prolonged by El Niño is currently underway — "the longest coral die-off on record," according to a statement released by the National Oceanic and Atmospheric Administration (NOAA) on Feb. 23.

Mark Eakin, coordinator of the NOAA Coral Reef Watch program, told Live Science that the event, which began in 2014 in the Pacific, could linger through 2017.

"We consider it a global bleaching event if it's widespread in all three of the major ocean basins — Indian, Atlantic and Pacific," he said. Eakin described current reports of bleaching that extend over half of the Southern Hemisphere, with severe bleaching in New Caledonia, Fiji and southern Indonesia, as well as in the GBR.

Even fast-growing corals take decades to develop, so damaged reefs will need time before they're restored to their former level of health, Eakin said.

And recovery time may be in short supply. Global bleaching events have been expanding their reach and increasing in severity since the first event was documented in 1998, Eakin told Live Science.

"We’re seeing prolonged high temperatures that cause bleaching coming back repeatedly. We're seeing areas that have seen high temperatures for two to three years in a row. There's no time for corals to recover," he said.

The 1998 global bleaching event was associated with a strong El Niño — the strongest on record — but as ocean temperatures rise, even a mild El Niño can trigger a devastating effect on the world's corals. And the global bleaching event that's underway right now began in 2014, before the current El Niño was active, Eakin said.

For the GBR, in spite of the extreme bleaching there may yet be some hope for its recovery. The upper part of the reef that sustained the most damage was in very good shape beforehand, which should improve its prospects for "bouncing back," according to Albright.

"And the lower two-thirds of the GBR is still in very good shape — not a lot of bleaching in those areas. So a lot of people are holding on to that as another piece of hope," Albright said.

"It’s really just a matter of whether or not we get another bleaching event in the next 10 years that would impede recovery," she added.

Follow Mindy Weisberger on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

From crippling drought in southern Africa to a record number of February tornadoes in the U.S. Southeast, an exceptionally strong El Niño has been making headlines around the globe as it tampers with the world’s weather.

While the event has begun its slow decline, those wide-ranging impacts will continue to be felt for weeks and months to come — good news for those in California, who need El Niño-fueled rains, but bad news for the many areas, like Indonesia, which is suffering from deep drought, food and water shortages, and wildfires.

Already this year, El Niño-related weather has cost billions of dollars in damage and left some 100 million people facing food and water shortages.

Through the interactive graphic below, Climate Central takes a look at how this major climate pattern typically influences the world’s weather, what it can mean for societies in the areas it affects, and what has actually been happening with this particular event, which ranks amongst the strongest on record. After all, no two El Niños are the same. For instance, while Southern California was drenched during the 1997-1998 El Niño, it has remained disconcertingly dry this time around.

First, the big picture: El Niño is most known for shifting a large pool of warm ocean waters from the western to the central and eastern tropical Pacific. That shift changes where heat is pumped into the tropical atmosphere, disrupting its typical circulation patterns. Those local disruptions cause a domino effect through the global atmosphere that can alter weather thousands of miles away.

There are two main circulation patterns that are affected. All around the tropics is a pattern of rising and sinking air — like a vertical loop — called the Walker Circulation. The rising air corresponds to areas of unsettled, rainy weather, while the sinking air creates a stable, dry clime. Normally in the tropical Pacific, a major area of rising air is found over the western portions, where the warmest waters are found. With the eastward shift from El Niño, that rising air (and its sinking counterpart) move eastward as well. This displacement shifts the other branches of the Walker Circulation around the tropics, pushing wetter weather over areas that might normally be dry and vice versa. These areas typically see some of the strongest impacts from El Niño because they are in a region more directly linked to it.

The changes in the Walker Circulation in turn cause shifts in another looping pattern called the Hadley Circulation that runs north-to-south to the Walker’s east-to-west. And those changes in the Hadley Circulation can affect the subtropical jet stream — an area of fast-moving air that guides storms — in both the Northern and Southern hemispheres. This is how El Niño can affect regions far from the tropics.

The changes in these main circulation patterns interact with other factors, like seasonal monsoons and other major climate patterns, which is why none of the typical impacts associated with El Niño are guaranteed. It merely shifts the odds in their favor.

Let’s dive in for a closer look at some of the local and regional impacts and what has actually played out this year:

Southeast Asia

Indonesia, and Southeast Asia more broadly, is one of the areas most directly impacted by El Niño. The eastward shift in the Walker Circulation means the normal area of rising air and rainy weather is shifted eastward as well, leaving the Indonesian area high and dry during much of the year. This can lead to drought that can cause water shortages and crop and livestock losses from dried up fields. Those losses then lead to food shortages and rising prices, and can also increase the odds of large wildfires.

This year has seen major drought grip Indonesia, Vietnam, Thailand, the Philippines and much of the U.S. Pacific Island territories. In Indonesia there were major delays in the planting of the rice crop, leading to concerns over food shortages. And when farmers set their usual fires to clear brush for planting, the dry conditions caused many to burn out of control, causing one of the biggest burn years on record and leading to a pall of smoke over the region. In Vietnam, drought has led to salinization issues in the Mekong Delta region, home to some 20 million people and a major rice growing area.

Drought has caused the Republic of the Marshall Islands and the Federated States of Micronesia to declare states of emergency, with some islands enacting water rationing and having to have water shipped in.

Australia

That same eastward shift of storm activity tends to bring drier conditions to northern Australia during the Southern Hemisphere summer and more broadly to the east in the winter. It also tends to bring warmer summer weather to southeast Australia because of the larger mass of stable, subsiding air in place. During El Niño years, drought and wildfires also become a concern here.

So far this year, Australia has seen a mixed bag of El Niño impacts. While dry conditions have been in place in much of the usual areas, some of the inland regions of the eastern part of the country actually had fairly normal rains. That may be due to exceptionally warm Indian Ocean waters providing more moisture to storm systems. The southeast has seen some major heat waves, though, with temperatures sometimes climbing above 100°F (40°C). The hot and dry conditions have helped create more favorable wildfire conditions, with several burning in Victoria this year. One of the worst destroyed 116 houses around Christmas.

India

India also tends to see drier weather during the Northern Hemisphere summer because the changes to atmospheric circulation patterns delay the onset of the seasonal monsoons. Monsoon rains are critical to supplying water for drinking and agriculture, and El Niño years tend to see drought develop in parts of India.

This summer, rainfall in India was 14 percent below normal and reservoirs were down by 30 percent, according to a United Nations report. That led to shortages of drinking water in some areas and caused rice, corn and soybean fields to dry up, setting off worries for food shortages and inflated food prices.

El Niño can lead to wetter weather in southern India, which also happened this year, with torrential rains that causedmajor flooding in the area around Chennai.

Pacific Ocean

Moving back out into the Pacific Ocean, the warmer ocean waters can cause bleaching of coral reefs, killing them. This event has seen one of the longest global bleaching events ever recorded, according to experts.

March Miracle? El Niño-Fueled Storms Return to California Longest Global Coral Bleaching On Record Isn’t Over Yet NOAA and NASA Team Up to Investigate Strong El Niño

Warmer ocean waters in that area also provide more fuel for hurricanes in the central and eastern Pacific Ocean basins. The atmospheric changes El Niño brings also mean more favorable winds for storm formation. This year sawabove-normal hurricane activity in the region, including the strongest storm ever directly measured in the Western Hemisphere. Hurricane Patricia, which had winds that clocked in at 200 mph, hit the west coast of Mexico, though its effects were mostly confined to less populated areas.

South America

Parts of South America are also more directly affected by El Niño. The warmer ocean waters off its west coast tend to bring warmer weather to coastal areas during the Southern Hemisphere winter. Those waters also make more moisture available to storms. Combined with changes to storm tracks linked to atmospheric circulation changes, this can mean wetter winter weather for central Chile. Several rounds of storms during this event had some benefits, bringing moisture to a region in drought and snows to ski resorts. But the rains also brought flooding and mudslides. A rare storm event in March saw parts of the bone dry Atacama Desert receive a year’s worth of rain in just one day. The Copiapó River — dry for nearly 17 years — filled to overflowing and flash floods swept through several towns. Come spring, that influx of water led to a surreal bloom of flowers across the desert that tends to coincide with rainy El Niño years.

The chain of changes to the Walker and Hadley circulations also tends to bring rainier weather to an area that includes Paraguay, northern Argentina, part of southern Brazil and Uruguay during the Southern Hemisphere summer. In December and January, heavy rains caused the worst flooding in the region in 50 years, displacing more than 200,000 people. The Paraguay River in Asunción reached more than 16 feet above its normal level in December. Thousands of acres of cropland were inundated and concerns were heightened for the spread of mosquito-borne disease like dengue fever and the Zika virus.

In northern Brazil and other countries in the north of South America, the eastward shift of the Walker Circulation brings sinking air and drier conditions. Those come with the usual tendency toward drought, water shortages and crop and livestock losses. Drought and those follow-on impacts have been recorded in northeastern Brazil, an area already vulnerable due to poverty and remoteness.

Some recent research has suggested that the exceptional heat and drought in the area may actually have helped fuel the rise of the Zika virus epidemic in the region. Heat promotes the growth of the mosquito that carries the disease, and during drought, residents tend to store water in containers in which the mosquitoes can breed.

Central America and the Caribbean

Further north, drier weather also tends to grip Central America and the Caribbean for the same reasons as northern South America. The area that spans Guatemala, Nicaragua, Honduras and El Salvador is experiencing one of its worst droughts in decades, according to the European Commission. Major crop losses have caused huge financial hits to farmers and left some 3.5 million people facing food shortages, the agency reported.

In the eastern Caribbean, 2015 was the driest year on record and led to water restrictions on many islands, including St. Lucia, St. Kitts, Barbados and Puerto Rico. Diminished water supplies also led to crop losses in the Dominican Republic, Haiti and other areas. As of August,Antigua had no surface water supplies, and by October it was using 100 percent desalinated water.

The subsiding air that leads to drought also tends to help tamp down on hurricane formation in the region. This year saw a below-average Atlantic hurricane season.

United States

Not far away, though, El Niño brings the opposite conditions to Florida. The shifts in the Hadley Circulation affect the subtropical jet stream that crosses the U.S., pushing it southward and making it extend further eastward. This puts Florida in a prime location for storms during the winter months, which is normally its dry season. It also ups the odds for tornadoes thanks to the added energy from the jet stream.

Florida did have a wetter than normal winter this year, and its southern tip had its wettest year on record. It also saw 18 tornadoes in January and February, compared to the seven it usually sees during those months.

While tornado activity may typically rise in Florida in El Niño years, it is usually tamped down in the area of the central U.S. known as Tornado Alley. The more southward jet blocks the moisture from the Gulf of Mexico that is key to fueling spring storms there. An experimental seasonal tornado forecast favors a below-average tornado seasonthere this year.

The tweak to the jet stream also tends to favor wetter weather over Southern California — much needed this year after four years of deep drought. While storms have been hitting California, they have mostly affected the northern portions of the state because the jet stream has been slightly further north than is typical during an El Niño. The rains shut off almost completely in February, bringing hot and dry weather to the state, though storms have since returned and look to bring at least some rain to Southern California.

Across the northern tier of the U.S., from the Northeast all the way up into eastern Alaska, El Niño tends to favor warmer than normal conditions. That has indeed been the case this year, with nearly all northern states recording one of their top 10 warmest winters. Alaska saw its second-warmest winter in the books, which has contributed to a lack of snow in varied locations there. That dearth of snow can have ecological impacts and promote the spread of invasive species. El Niño wasn’t the only reason Alaska was warm, though, as the Arctic more broadly was exceptionally warm this winter.

Africa

And, finally, across the Atlantic in Africa, some of the populations most vulnerable to El Niño’s impacts are found.

In the Southern Hemisphere summer, the eastward shift of the Walker Circulation leads to rising air over Kenya, southern Somalia and southern Ethiopia, which can enhance seasonal rains. Increased rains can lead to flooding, mudslides and outbreaks of diseases.

Heavy rains in the area began in late October, inundating villages and agricultural lands. By January, more than 100,000 people had been displaced and 112 killed, according to the International Federation of Red Cross and Red Crescent Societies. Authorities are concerned about the spread of both waterborne diseases, such as cholera, and mosquito-borne ones, particularly Rift Valley Fever, which tends to occur in years with unusually heavy rainfall.

Just to the north, in Ethiopia and Somalia, El Niño has brought dry conditions that have exacerbated a drought and led to crop failures and widespread livestock deaths, according to the United Nations Food and Agriculture Organization.

Drought has also gripped large parts of southern Africa, particularly the northeast of South Africa, Mozambique and Zimbabwe. The changes to the Walker and Hadley circulations interact with the normal monsoon there and tend to suppress monsoon rains, leading to drought, crop losses and food and water shortages.

Severe rainfall deficits this year have lead to widespread drought that has decimated the maize crop, costing hundreds of millions of dollars in losses. Zimbabwe declared a state of disaster as some 2.5 million people are in need of food aid. South Africa, normally an exporter of corn, is expected to have to import it this year to feed its citizens.

The drought has also severely reduced the flow of rivers that feed hydropower dams, leading to power rationing and even blackouts in the region. The flow down the majestic Victoria Falls has reached a 30-year low.

While El Niño has shown signs in recent weeks that it is beginning to weaken, it will likely be late summer or early fall before it fully dissipates. Its weather affects around the world are expected to continue for several more months, and the impacts of that weather could reverberate for years to come, making it one for the record books.

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This article was originally published on Climate Central.

Thousands of dead seabirds have washed up on Alaskan shores over the past nine months. And while a dead bird washing ashore is a fairly common occurrence, these large numbers are leaving scientists concerned and confused.

Nearly 8,000 common murres (Uria aalge) were found along the shores of Whittier, Alaska, in early January. Over the New Year's holiday, Alaska experienced four days of gale-force winds from the southeast that resulted in dead birds washing ashore, said Robb Kaler, a wildlife biologist for the Alaska branch of the U.S. Fish and Wildlife Service (USFWS). Scientists have known for some time that the key to surviving strong storm winds is having an energy reserve, according to an expert at Tufts University, and Kaler and his colleagues think that the common murres were not finding enough food this season, which may be why so many didn't make it through the storm.

In cases like these, experts typically measure the number of dead birds per kilometer, said Julia Parrish, a professor in the School of Aquatic and Fishery Sciences at the University of Washington in Seattle and executive director of the Coastal Observation and Seabird Survey Team (COASST), which is one of the organizations studying areas where these birds are washing ashore, alongside the USFWS and the U.S. Geological Survey National Wildlife Health Center (NWHC). For the Whittier survey, the final measurements came to approximately 4,600 birds per kilometer, Parrish told Live Science. [5 Mysterious Animal Die-Offs]

The common murre is "one of the most abundant and widespread seabirds in Alaska," Kaler told Live Science in an email. While other dead seabirds are being reported on Pacific shorelines, current reports indicate that about 99 percent of the animals are common murres, Kaler said.

Seeing a dead seabird on the beach is not altogether unusual, especially during September and October, when the birds are leaving their breeding colonies, Parrish said. However, dead common murres started showing up in Alaska in March.

"This is really weird, because that is the beginning of the breeding season," Parrish said. "That's when [seabirds] are [usually] fat and sassy."

What's going on?

So far, the NWHC has examined 100 bird carcasses, and most of the birds seem to have died due to starvation, Kaler told Live Science.

"While we know murres are starving," Kaler said, "we do not understand the mechanism."

There is a chance that saxitoxin, a toxin related to paralytic shellfish poisoning, or domoic acid, a toxin that causes amnesic shellfish poisoning, could be responsible for some of these deaths, he said. But both of these toxins are difficult to detect in birds that have nothing in their stomachs or gastrointestinal tracts, which was the case with most of these animals, Kaler said.

In the past, seabird die-off events — in which thousands of birds die in a short period of time — have been associated with strong El Niño events, Kaler said. In 1993, there was another die-off of common murres recorded in the northern Gulf of Alaska, where scientists found about 3,500 dead or dying common murres along the shoreline over a period of six months. Scientists calculated that over that period, about 10,900 bird carcasses actually made it to shore, according to a 1997 study published in the journal Marine Pollution Bulletin.

Because researchers were able to monitor only a small fraction of the beaches in Alaska, that study's scientists projected that the actual final death count in 1993 was at least 120,000 birds.

With this most recent event, "[w]e assume the die-off is connected to one of the largest oceanographic-atmospheric events, known as 'The Blob,'" Kaler said. This event is the presence of a large area of water that falls well above the average temperature usually observed in the North Pacific, he said. "We do not know how [that] this relates to El Niño or climate warming, but we believe they are factors," Kaler said.

The USFWS also noted in a recent bulletin that common murres have turned up at locations as far inland as Fairbanks, Alaska, where the birds have been seen swimming in rivers and lakes. Wildlife biologists consider this to be unusual behavior, since common murres are seabirds and so don't usually show up so far inland, Parrish told Live Science.

Additionally, while the die-off has been most visible in Alaska, similar events affected seabird populations in Washington, Oregon and California during the months of September and October, Parrish said.

What does this mean?

The behaviors of seabirds are often indicators of what is happening in the marine system, said the U.S. Fish and Wildlife Service. Current estimates of the common murre death toll in the recent die-off have suggested that more than 100,000 birds have probably died over the past nine months, and dead birds are likely to continue showing up through the spring, Kaler said.

It is important to note that this high death count doesn't mean that common murres are in danger as a species. There are an estimated 2.8 million common murres in Alaska, Parrish said. This means that current estimates of the die-off account for only approximately 3 percent of the total common murre population in the state.

That's not to say that the appearance of large numbers of dead birds on beaches isn't of concern, Parrish said. Scientists are speculating that this event indicates a species struggling to deal with altered circumstances, he said.

"When there are heat waves during the summertime, you always hear about mortalities in the inner city [from people who don't have air conditioning] and [so] they just have to deal with" the heat, Parrish said. "None of these birds have air conditioning."

Follow Elizabeth Newbern @liznewbern. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

A massive winter storm that is expected to bring snow and ice to the eastern United States in the next 48 hours dwarfs the central part of the country in a new satellite image.

The National Oceanic and Atmospheric Administration's GOES-West satellite spotted this cloudy view of the large storm near the Gulf Coast today (Jan. 21) at 10 a.m. EST. (The satellite photo also spied a separate storm swirling over the Pacific Ocean.)

The NASA-NOAA Suomi NPP satellite captured another view of the looming winter storm yesterday (Jan. 20) at 2:30 p.m. EST, showing clouds and snow cover stretching from northern Texas into the Great Lakes states. The low-pressure system, which originated in the Eastern Pacific, is headed toward the mid-Atlantic states. The National Weather Service is warning of a potentially "crippling" snowstorm in those areas tomorrow and Saturday. [VIDEO: Watch the Developing Storm from Space]

Much of the East, from as far south as northern Georgia to as far north as New York City, is under weather alert, ranging from winter storm warnings in eastern Tennessee, Kentucky and western North Carolina to a blizzard watch in Washington, D.C, Baltimore and up the I-95 corridor through New Jersey.

"At this moment, this still looks like it's going to be northern Virginia and Maryland's most memorable snow," said David Robinson, the state climatologist of New Jersey. "A question remains just where exactly the heaviest snowfall totals will fall, just where the strongest winds will be and where the coastal flooding will be worst."

Volatile winter

The storm will track across the Tennessee Valley tonight and Friday, ultimately hitting the mid-Atlantic states Saturday, with lessening snow expected by Sunday. Storms like the one bearing down on the eastern United States typically have a band of heavy snowfall about 100 miles (161 kilometers) wide, Robinson told Live Science. North of this band, precipitation peters out, leading to low overall totals. South of this band, temperatures are warm enough that snow turns to rain.

"This is a multifaceted nor'easter, as they all tend to be, laden with strong wind and impacts on the coast and heavy precipitation of one form or another," Robinson said.

El Niño's influence may also be at play, Robinson said. The storm "fits the pattern of volatility that we often see in weather, really across the country, during an El Niño winter," he said.

The winter of 2015-2016 has so far been marked by an active storm pattern in the western United States, with unseasonably warm temperatures and unusual midwinter thunderstorms in the South. In late December and early January, the Mississippi River flooded to levels not seen since 1993, thanks to heavy snows and rainfall in the western and central parts of the country. A rare December tornado outbreak from Indiana to Alabama killed 13 people between Dec. 23 and Dec. 25.

Meanwhile, warm temperatures made Christmas a balmy holiday for many on the East Coast. New York City experienced its warmest Christmas on record, with temperatures reaching 66 degrees Fahrenheit (19 degrees Celsius). On Christmas Eve, the mercury hit 72 degrees F (22 degrees C) at LaGuardia Airport in New York, breaking a 76-year record. The previous high temperature that day, according to NOAA's National Centers for Environmental Information, was 63 degrees F (17 degrees C).

Ice, wind and floods

If volatility is a feature of El Niño winters in the United States, so is an active East Coast storm track, Robinson said.

"We have seen coastal storms aplenty during El Niño winters," he said. Those storms don't always translate to snow, though, he added. Some mid-Atlantic El Niño years have been virtually snow-free, while others have seen large snowstorms.

Regardless of snow totals, the incoming storm is likely to be a major event, meteorologists say. Forecasts predict water levels 3 to 4 feet higher than normal along the New Jersey coast down into Delaware, Robinson said, and winds could gust more than 60 mph (96.5 km/h).

Washington, D.C., and the surrounding area is under a blizzard warning, with about 24 inches (60 centimeters) of snow expected for the capital city and 24 to 30 inches (60 to 76 cm) in the western suburbs, according to the National Weather Service. Gusty winds, ice and up to a foot (30 cm) of snow are expected in Kentucky. Detailed regional weather advisories and forecaster discussions can be found at http://www.weather.gov/.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.