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Saturday, August 29, 2026

No electricity needed for solid-state cooling: Heat becomes cold

Researchers of KIT and the University of Tsukuba have developed – as a world first – a heat-driven, elastocaloric cooling system that leverages waste heat and solar energy for sustainable cooling

Karlsruher Institut für Technologie (KIT)

image:
The new cooling system combines two nickel-titanium foils: a heat-responsive foil generates motion, which a second foil uses to produce cooling. (Image: Concept by Yi-Ting Hsiau and Jingyuan Xu, KIT; visual design by Ella Maru Studio)
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Credit: Image: Concept by Yi-Ting Hsiau and Jingyuan Xu, KIT; visual design by Ella Maru Studio

The basic cooling principle for fridges, A/C systems, or datacenters has been the same for more than a hundred years. An electricity-driven compressor transfers heat carried by a refrigerant from one location to another. Since the cooling demand is constantly on the rise, cooling and heating meanwhile account for almost half of the global energy consumption. This is aggravated by the fact that many common refrigerants contribute to global warming. Elastocaloric solid-state cooling is considered a promising alternative: Shape-memory alloys tend to cool down once a previously applied mechanical load is released. However, even elastocaloric systems have so far relied on an electrically driven actuator to generate the required force – which means that they could not directly use abundantly available heat sources such as waste heat or solar energy.

Driven by Heat instead of Electric Power

This is exactly where the new approach developed by the research team comes into play, coupling two ultra-thin nickel-titanium films that have complementary functions. The first film uses a shape-memory effect: Once it is heated up, it starts to shrink, thereby converting thermal energy directly into mechanical work – without the help of an electric motor. This motion immediately transfers to the second film where cyclic loading and unloading brings about reversible alterations in the crystal structure that generate cold. Thus, heat replaces the electrically driven actuator, which was previously used to drive elastocaloric cooling systems.

“The crucial innovation is that we combine two complementary functions of shape memory alloys, with one film converting heat into mechanical work and the other film converting this work into cold,” said Dr. Jingyuan Xu who leads the Young Investigator Group of the ZEco Thermal Lab at KIT’s Institute of Microstructure Technology (IMT). “This way, we’re establishing a new approach to drive solid-state cooling, thereby opening up exciting possibilities for the use of waste heat and solar energy.”

First Cooling Capacity Values Confirmed in the Lab

At an actuator temperature of 86° Celsius, the prototype of this system achieved a temperature difference of 4° Celsius on the component level, while the temperature change in the elastocaloric refrigerant amounted to nearly 13° Celsius. This way, the researchers were able to prove the feasibility of their concept in experiment for the first time. The setup also worked reliably with an external heat source that provided 130° Celsius, demonstrating that the system is capable to work with real-world heat sources. “The decisive moment for us was when we were able to measure the cold that had indeed been generated by a heat-driven system,” said Yi-Ting Hsiau, lead author of the study and doctoral researcher at the IMT. “This showed us that the principle doesn’t just work in theory.”

The current setup has been designed as a feasibility study and is therefore not optimized for a maximum cooling capacity yet. The team is already working on connecting multiple films in parallel to increase the cooling capacity. Potential applications range from cooling of processors in computers, which could use their own waste heat for this purpose, to cooling of sensitive electronics in automobiles using the heat from the drive train.

The study was conducted in collaboration with the University of Tsukuba in Japan, paving the way for heat-driven solid-state cooling that is fit for use in practice. “We believe that this is only the beginning,” said Xu. “By scaling up this technology we want to develop compact cooling systems that leverage abundantly available heat sources for sustainable cooling.”

Funds for this study came from the Carl Zeiss Foundation (CZS Nexus project), the Baden-Württemberg Foundation (elite postdocs program), and the Hector Fellow Academy.

In close partnership with society, KIT develops solutions for urgent challenges – from climate change, energy transition and sustainable use of natural resources to artificial intelligence, sovereignty and an aging population. As The University in the Helmholtz Association, KIT unites scientific excellence from insight to application-driven research under one roof – and is thus in a unique position to drive this transformation. As a University of Excellence, KIT offers its more than 10,000 employees and 23,000 students outstanding opportunities to shape a sustainable and resilient future. KIT – Science for Impact.

Journal

Nature Energy

DOI

10.1038/s41560-026-02122-6

Article Title

Y.-T. Hsiau, S. Miyazaki, M. Kohl, J. Xu: Heat-driven elastocaloric cooling with shape memory films. Nature Energy, 2026.

Article Publication Date

28-Aug-2026

Insects could face an uphill battle adapting to climate change

British Ecological Society

Reduced oxygen levels and air pressure at higher elevations may limit the ability of insects to move upslope to escape a warming climate, with potential consequences for the essential services they provide, like pollination. This is according to a new review of research in The British Ecological Society journal, Functional Ecology.

Under a warming climate, many species are shifting their range to higher elevations to remain in suitable temperature zones. However, conditions at higher elevations such as thinner air and less oxygen pose unique challenges to insects because of their size, lifecycle and way of breathing.

To understand how moving to higher elevations could affect different insect species, researchers from the University of Montana reviewed research on the physiological effects of hypoxia (low oxygen levels) and hypobaria (low pressure) on insects.

They found that flying insects particularly struggle at higher elevations because the thinner air means they need to generate more lift and expend more energy flying, while reduced oxygen concentrations limit the ability of their breathing system to supply oxygen rapidly enough to the flight muscles.

Insects with active larval stages, like actively feeding caterpillars, also struggle because of their energy and oxygen demands. Insects with aquatic larval stages, like dragonflies, are already limited by the amount of oxygen in water, and this is exacerbated at higher elevations.

Higher rates of water loss at high altitudes were also identified as a barrier to insects’ ability to survive in these conditions.

Professor Art Woods, the lead researcher of the study, said: “Our study suggests that low oxygen levels and low atmospheric pressure at higher elevations may negatively affect insect performance, meaning moving uphill may be more difficult than expected. We think of moving uphill as an ‘escape valve’ for animals but it may not be the solution we hope for.”

Insects are key players in many ecosystems and perform essential services such as pollination and decomposition. If they are unable to move upslope under climate change, this could disrupt pollination services, affecting crop production and ecosystem functioning.

The researchers were particularly surprised by the limitations lower oxygen levels place on insects. Professor Woods added: “Because insects get their oxygen through a network of external openings and internal tubes throughout their body, it's easy to imagine that they have little problem getting all the oxygen they need. If humans can go to moderately high elevations with only minor discomfort, surely insects won’t have a problem?

“But the data from several experiments suggest that demand for oxygen by active stages of insects, especially growing juveniles and flying adults, is high enough that their respiratory systems struggle to deliver oxygen fast enough at even modestly higher elevations."

The researchers call for more targeted research into high-elevation species to better understand the physiological constraints of shifting ranges upslope. Knowledge gained from this research will be vital for informing conservation strategies.

-ENDS-

Journal

Functional Ecology

DOI

10.1111/1365-2435.70416

Method of Research

Literature review

Subject of Research

Animals

Article Title

The oxygen and pressure physiology of upper elevational range limits in insects

Article Publication Date

28-Aug-2026

Two internationally recognized scholars join UVic through federal research chair program

AMERIKAN SCIENTISTS FLEE TO CANADA

University of Victoria

A $16 million federal investment announced on Thursday is helping the University of Victoria (UVic) expand its leadership in marine sustainability and preventative health research through the Eddie Goldenberg Research Chairs of Canada program.

"We are delighted to welcome two outstanding global leaders to UVic through this program. These new chair appointments align strongly with UVic’s lofty ambitions in ocean science and mental health. Elliott Hazen and David Almeida will strengthen our research community, catalyze new collaborations and help address urgent global challenges.”

—Lisa Kalynchuk, UVic’s vice-president research and innovation

Hazen joins UVic following a 12-year career leading climate and ecosystem programs with the US National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center and recent professorship at the University of Aarhus in Denmark. He will lead research aimed at improving climate-ready ocean stewardship through real-time data and partnerships with government and Indigenous communities.

"The goal is to shift marine governance from reactive to proactive. Rather than responding after fisheries collapse, whales are entangled in fishing gear or hit by a ship, or climate-driven disruptions reshape human uses of the ocean, we can identify early ecosystem warning signals and help managers anticipate risk and respond in near-real time.”

—Elliott Hazen, Eddie Goldenberg Research Chair

Hazen’s research will involve collaborators at Ocean Networks Canada, Fisheries and Oceans Canada, Environment and Climate Change Canada, Dalhousie University and Indigenous communities. The work will integrate Indigenous knowledge and data sovereignty principles to support climate-responsive ocean stewardship.

UVic’s other Eddie Goldenberg Research Chair will focus on prevention-focused health research. Almeida joins UVic from Pennsylvania State University where he was a distinguished professor of human development and family studies. At UVic he will establish a digital and community-based research hub that uses mobile and wearable technologies to measure changes in stress, mood, sleep and cognition in everyday settings.

"Most health challenges don’t begin in hospitals. They develop gradually through the accumulation of everyday experiences. By combining detailed daily measurements with biological indicators and real-world implementation, we can identify risk trajectories years before clinical impairment becomes established. This prevention-first approach has the potential to transform how mental health is monitored and supported across the lifespan.”

—David Almeida, Eddie Goldenberg Research Chair

His research will examine connections between daily experiences and long-term outcomes related to mental health, cognitive decline, aging and cardiometabolic disease. Almeida also plans to build a network of researchers, community organizations, health care providers and policy leaders to accelerate the use of prevention-focused approaches.

Through this work, UVic will help advance Canada’s leadership in prevention-focused mental health and aging science while supporting innovative approaches to improving health and well-being.

The Eddie Goldenberg Research Chairs of Canada program, formerly named the Canada Impact+ Research Chairs, is part of the Canada Global Impact+ Research Talent Initiative, which supports Canadian institutions to recruit leading researchers from around the world.

‘Damaging the Antarctic damages us all’ – scientists warn of the potential impacts of coastal freshening

University of Plymouth

The giant amphipod species Paraceradocus miersi — image:
New research by the University of Plymouth and the British Antarctic Survey focused on the giant amphipod species *Paraceradocus miersi*, found in abundance in Antarctic waters and relatives of the sandhoppers on temperate beaches
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Credit: John Spicer/University of Plymouth

Many of the Antarctic’s smallest inhabitants have evolved over millions of years so their body fluids are similar in chemical composition to that of sea water. However, a combination of melting glaciers, increased rain and extreme weather events means that waters in some of the remotest parts of the planet are increasingly being exposed to a reduction in salt levels.

Scientists refer to this phenomenon as freshening, and a new study has highlighted the impact this could have on species living in the shallow coastal waters off Antarctica. It has led researchers to warn that continued coastal freshening may pose a significant threat to many marine invertebrates living in the region, but that it could also change the nature of the global ocean.

The research was conducted by scientists at the University of Plymouth and the British Antarctic Survey (BAS), and builds on previous work by the organisations to assess the impact of changing ocean conditions on some of the planet’s smallest, but most important, inhabitants.

Professor John Spicer, Professor of Marine Zoology at the University of Plymouth and the study’s lead author, has spent almost 40 years examining the effect of climate change on marine organisms.
He said: “I was working at the Rothera Research Station on the Antarctic peninsula in 2017 when there was an extreme freshening event. I was interested in the effect this would have on one of the region’s largest amphipods, and we found that even if the water is diluted fractionally, the amphipods lose their salts, gain water and their gills are damaged.

“This is important for the whole planet as while Antarctica and its wildlife are wonderful, they are also essential to a functioning environment. Damaging the Antarctic damages us all, and if there is freshening it will not have to be very strong before the health of many invertebrate species will be severely impacted.”

Published in the Marine Environmental Research journal, the new research focused on the giant amphipod species Paraceradocus miersi, found in abundance in Antarctic waters and relatives of the sandhoppers on temperate beaches.

Using creatures collected from Ryder Bay on the Antarctic Peninsula, researchers assessed how their body fluids and internal organs responded when exposed to a simulated freshening experiment. They found that when exposed to reduction in salt levels within the water, the species was still able to regulate some of the key chemicals – including calcium – which are critical to its bodily functions.

However, its overall regulation of the ions that make up the full concentration of sea water is impaired meaning the amphipods lose their salts, gain water and their gills are damaged. This, the researchers say, could have led to significant deaths among shallow-dwelling individuals during the 2017 freshening event and other similar events before and after it.

Dr Simon Morley, an Ecophysiologist at the British Antarctic Survey and a study co-author, added: “As climate change continues, environments will change beyond the conditions that animals living there can cope with. In the seas around Antarctica, the biggest signal of climate change is the melting of ice and this is adding large quantities of freshwater into the oceans. This lowering of salinity could have dramatic impacts, reshaping the communities on the sea floor. Our study provides critical evidence of what could happen to different species in the future.”

‘Damaging the Antarctic damages us all’ [VIDEO]

Professor John Spicer, Professor of Marine Zoology at the University of Plymouth and the lead author of the new study published in Marine Environmental Research, has spent almost 40 years examining the effect of climate change on marine organisms

Journal

Marine Environmental Research

DOI

10.1016/j.marenvres.2026.108368

Method of Research

Experimental study

Subject of Research

Animals

Article Title

The giant Antarctic amphipod Paraceradocus miersi will not fare well if freshening continues in the Southern Ocean

Article Publication Date

24-Aug-2026

Hotter tropical pool temporarily slows Antarctic ice loss

Chinese Academy of Sciences Headquarters

image:
Totten Ice Shelf, East Antarctica, photographed in late 2019.
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Credit: Image by Prof. Yoshihiro Nakayama

A warming pool of tropical ocean acted like a “regulator,” dialing up snowstorms over East Antarctica and contributing to a brief net ice-sheet mass gain of 695 billion tons, according to a new study published in Nature on August 19.

The study revealed that sustained warming of the tropical warm pool during 2021–23 triggered a Rossby wave train propagating toward Antarctica, formed a north–south dipole circulation over East Antarctica, reorganized moisture transport, and enhanced regional snowfall, thereby temporarily slowing Antarctic ice-sheet mass loss.

The Antarctic Ice Sheet is one of the major sources of uncertainty in future global sea-level rise. Over the past two decades, it has experienced sustained mass loss at a rate of approximately 140.5 billion tons per year. However, its mass increased by about 695 billion tons during 2021–23, marking the largest mass-gain event recorded by the GRACE satellites.

To identify the cause, a research team led by the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) combined gravity-satellite observations, ice-core snow-accumulation records, and atmospheric circulation model simulations to investigate the atmospheric circulation mechanisms and moisture sources underlying this mass-gain event.

The results showed that, during 2021–23, sustained warming occurred in the tropical warm pool located in the region where the tropical western Pacific and eastern Indian Ocean meet. This warming triggered a Rossby wave train toward high southern latitudes. Eddy-mean flow feedbacks amplified and sustained the resulting circulation, establishing a north–south dipole with low- and high-pressure anomalies south of Australia and along the East Antarctic coast, respectively. The dipole redirected moisture and enhanced atmospheric-river transport from the midlatitude Indian Ocean to East Antarctica.

Water-vapor tracking simulations showed that, under the influence of the dipole circulation, moist air from the midlatitude Indian Ocean was transported to East Antarctica, allowing more atmospheric rivers to reach the region. This resulted in persistent heavy snowfall over the Queen Mary Land–Wilkes Land region and increased ice-sheet mass.

Atmospheric circulation model experiments confirmed that warming of the tropical warm pool was the direct driver of the circulation and snowfall responses. The increase in regional snowfall attributable to anthropogenic forcing was equivalent to only 9% of the observed snowfall anomaly, indicating that atmospheric moistening caused by global warming was not the primary cause of this event.

Further observations and simulations showed that similar sustained tropical warm-pool warming events occur approximately once every decade. The tropical warm pool therefore acts like a remote “regulator,” influencing multiyear variations in snowfall and ice mass over East Antarctica.

However, this temporary slowdown cannot reverse the long-term trend of Antarctic ice-sheet mass loss. The West Antarctic Ice Sheet continues to lose ice, while some outlet glaciers in East Antarctica are also threatened by basal melting of ice shelves and accelerated ice flow caused by warm ocean waters.

This study not only reveals the mechanism by which sustained tropical warm-pool warming drove a temporary increase in Antarctic ice-sheet mass, but also shows that the north–south dipole circulation over East Antarctica plays a key role in connecting the tropics with ice-sheet mass changes.

“We found a previously underrecognized ‘tropical warm pool–East Antarctic Ice Sheet’ teleconnection pathway,” said WANG Yunhe from IOCAS, first author of the study. “Our research provides a theoretical basis for understanding Antarctic ice-sheet mass changes and conducting future research on the East Antarctic climate.”

Teleconnection mechanism linking tropical warm-pool warming to temporary Antarctic ice-sheet mass gain.

Credit

Image by IOCAS

Journal

Nature

DOI

10.1038/s41586-026-10912-x

Article Title

Multiyear tropical warm pool warming drives slowdown in Antarctic mass loss

Article Publication Date

19-Aug-2026

El Niños more intense over last 40 years than previous 1,000, according to U-M study

University of Michigan

Galápagos coral colony — image:
The Galápagos Islands are known for their astounding biodiversity, a result of high nutrients and the mixing of cool and warm waters, according to Julia Cole, chair of the University of Michigan Department of Earth and Environmental Sciences.
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Credit: Credit: Courtesy photo, Greg Asner

ANN ARBOR—As an El Niño of historic proportions is taking shape in the tropical Pacific, a University of Michigan study has found that El Niño events have become nearly 40% stronger in the last 40 years than they were in the pre-industrial era.

In fact, the study, which examined modern and ancient corals in the Galápagos Islands, found that El Niño events in the last four decades were stronger than any in the 1,000 years prior to about 1850, when humans began impacting the climate with greenhouse gases.

"We don't see a time in the past where El Niños have been as strong as today, and we show that the strength of El Niño changes in parallel with the warming of global temperature," said lead author Julia Cole, professor and chair of the U-M Department of Earth and Environmental Sciences. "Our findings tell us that the big El Niño events of the last 40 years are not normal in the context of the last thousand years."

El Niño is a natural phenomenon that, every few years, causes the tropical Pacific to become warmer than usual. Under normal conditions, trade winds blow along the equator from east to west. This pushes warm water from South America toward Australia. But when the trade winds weaken, warm water spreads eastward, back towards South America, kicking off an El Niño event.

The atmospheric circulation responds, as strong rainfall shifts from Indonesia into the central Pacific, leaving the western Pacific in drought. This weakens the trade winds further, locking in El Niño conditions that can persist for one to two years. These temperature and precipitation fluctuations originate in the tropical Pacific, but they affect weather all over the world.

Storm tracks over the U.S. shift southward, bringing more rain to the desert southwest and less to the northwest. Similar shifts around the world lead to droughts and flooding that bring disease, crop failure, wildfires and other crises that impact people's health and well-being.

"The question is not whether the current El Niño is going to happen, but how bad is it going to be, and how bad will the impacts be?" Cole said. "This event is superimposed on global warming, and it's likely to supercharge the temperature increase that we would normally see from greenhouse gases. There are forecasts that we might get as hot as 1.7 or 1.8 degrees Celsius above pre-industrial temperatures, which is quite a bit higher than the current record."

The findings, published in Science, were supported by the U.S. National Science Foundation and the United Kingdom Natural Environmental Research Council.

A history written in coral

To examine historic El Niño patterns, Cole and fellow researchers sampled cores from 13 corals, including living colonies and boulders of ancient coral, from the Galápagos Islands. Corals grow one to two centimeters per year by secreting layers of calcium carbonate. The chemistry of these layers provides a record of the seawater temperature in which the corals grew.

El Niño extremes occur every few years, so the researchers focused on core samples that spanned at least 20 years. Sampling the cores a millimeter at a time, the group measured two aspects of the coral skeleton's chemistry. They analyzed the ratio of the elements strontium to calcium, which depends on the temperature at which the coral grew, and supplemented these results with analysis of the ratio of oxygen isotopes, also a measure of temperature at this site.

They were left with a history of variations in temperature in the Galápagos—a location, Cole says, where El Niño has its largest impact. They saw that strong El Niños occurred in the last 40 to 50 years, whereas the El Niños prior to that time period showed "a pretty consistent pattern of lower intensity El Niños."

"We kept adding records thinking well, this is going to get more complicated, but it really didn't," Cole said. "This is such a clear story."

Confirming the connection

The researchers then examined whether natural processes could have caused similar intensifications of El Niño over the past thousand years. To do this, they used climate models that simulate the last thousand years using histories of volcanic eruptions and solar variability. The models found no large shifts in El Niño that suggested natural processes could create such large changes.

Cole says their findings underscore the need to mitigate more global warming.

"El Niño is a really big source of climate extremes, and so if it's getting stronger, the impacts are getting stronger. Impacts like droughts, floods, wildfire and food insecurity," she said. "Changes in the hydrologic cycle also lead to issues like damage to infrastructure: floods that wipe out homes, highways or railroads, or to health effects, such as diseases like cholera.

"We believe global warming is supercharging El Niño, and if that's true, then we expect stronger climate extremes that will amplify ecological, infrastructural and human losses. No country has the resources to be fully protected from these impacts. This is one more reason we need to move away from fossil fuels, the root cause of the problem."

The Galápagos National Park and the Charles Darwin Research Station in Galápagos also provided support for the research. Cole's co-authors include U-M researchers Kelsey Dyez, Cameron Tripp, Jonathan Overpeck and alumnus Jake Okun; University of Arizona researchers Diane Thompson and Marcus Lofverstrom; Samantha Stevenson-Karl of the University of California, Santa Barbara; University of Edinburgh researcher Sandy Tudhope; Colorado College researcher Allison Lawman; University of Illinois researcher Jessica Conroy; Gloria Jimenez of Moody's Risk Management Services; and University of Minnesota researcher R. Lawrence Edwards.

Ancient corals like these at Urvina Bay in the western Galápagos preserve a history of ocean temperature going back millennia.

Credit

Julia Cole, University of Michigan

Journal

Science

DOI

10.1126/science.ady2660

Article Title

Recent strengthening of eastern Pacific ENSO is unprecedented in the last millennium paleorecord

Article Publication Date

27-Aug-2026

El Niño has become more intense over last 40 years than the previous 1,000 years

A stronger El Niño will amplify this natural cycle's capacity for disruption and destruction

University of California - Santa Barbara

(Santa Barbara, Calif.) — An El Niño of historic proportion is taking shape in the tropical Pacific. As a result, water temperatures off Santa Barbara climbed into the low 70s Fahrenheit in late August, and anglers have reported catching dorado and yellowtail around the Channel Islands.

While 2026 promises exceptional conditions, a new study in the journal Science found that El Niño events have become nearly 40% stronger in the last 40 years than they were in the pre-industrial era.

In fact, the authors — who examined modern and ancient corals in the Galápagos Islands — found that El Niño events in the last four decades were stronger than in any of the 1,000 years prior to about 1850, when humans began impacting the climate with greenhouse gases.

“Thanks to these new coral reconstructions, we can go farther back in the eastern Pacific's past than we ever could before,” said co-author Samantha Stevenson, an assistant professor at UC Santa Barbara’s Bren School of Environmental Science & Management. “When we do that, we see that El Niño has been getting stronger, and that the changes have really taken off in the past few hundred years.”

“We show that the strength of El Niño changes in parallel with the warming of global temperature,” added lead author Julia Cole, professor and chair of University of Michigan’s Department of Earth and Environmental Sciences. “Our findings tell us that the big El Niño events of the last 40 years are not normal in the context of the last thousand years.”

A natural cycle with large impacts

El Niño is a natural phenomenon that, every few years, causes the tropical Pacific to become warmer than usual. Under normal conditions, trade winds blow along the equator from east to west. This pushes warm water from South America toward Australia. But when the trade winds weaken, this warm water spreads eastward, back towards South America, kicking off an El Niño event.

The atmospheric circulation responds, in turn. Strong rainfall shifts from Indonesia into the central Pacific, leaving the western Pacific dry. This weakens the trade winds further, locking in El Niño conditions that can persist for one to two years. While these fluctuations in temperature and precipitation originate in the tropical Pacific, they affect weather all over the world.

These changes push the jet stream farther south in the western U.S. This steers atmospheric-river storms away from the Pacific Northwest toward California. “A big El Niño tends to mean wet winters for us in Southern California,” Stevenson said. Often, conditions reverse the following year under “La Niña”.

Similar shifts around the world lead to droughts and flooding that bring disease, crop failure, wildfires and other crises that impact people's health and well-being. “The question is not whether the current El Niño is going to happen, but how bad is it going to be, and how bad will the impacts be?” Cole said. “This event is superimposed on global warming, and it's likely to supercharge the temperature increase that we would normally see from greenhouse gases.”

Some forecasts suggest we might get as hot as 1.7º or 1.8º Celsius (3.1º or 3.2º F) above pre-industrial temperatures, “which is quite a bit higher than the current record,” Cole added.

A history written in coral

To examine historic El Niño patterns, the authors sampled cores from 13 corals — including living colonies and boulders of ancient coral — from the Galápagos Islands. Corals grow one to two centimeters per year by secreting layers of calcium carbonate. The chemistry of these layers provides a record of the seawater temperature in which the corals grew.

Since El Niño extremes occur every few years, the researchers focused on core samples that spanned at least 20 years. Sampling a millimeter at a time, the group measured two aspects of the coral skeleton's chemistry. They analyzed the ratio of the element strontium to calcium, which depends on seawater temperature. They supplemented these results by looking at the ratio of the different isotopes, or atom weights, of the element oxygen, also a proxy for the temperature of the site.

The team was left with a history of variations in temperature in the Galápagos — a location where El Niño has its largest impact, Cole explained. They saw that strong El Niños occurred in the last 40 to 50 years, whereas the El Niños prior to that time period showed “a pretty consistent pattern of lower intensity.”

“We kept adding records thinking ‘well, this is going to get more complicated,’ but it really didn't,” Cole said. “This is such a clear story.”

Confirming the connection

The researchers then examined whether other natural processes could have caused similar intensifications of El Niño over the past millennium. To do this, they used climate models that account for histories of volcanic eruptions and solar variability. The models found no reason to believe such large shifts in El Niño were caused by other natural processes.

“I’m concerned that none of the climate models picked up on the increase we observed in the coral record,” Stevenson said. “That probably means the models are missing something about how El Niño responds to climate change, and we need to know why that's happening.” Her group is currently investigating the subtle differences between climate models in an effort to further improve predictions.

The findings underscore the need to seriously tackle global warming. “If this trend continues into the future, ‘super El Niños,’ like the one developing right now, might become much more common — with all the impacts that go along with them,” Stevenson said.

“Impacts like droughts, floods, wildfire and food insecurity,” Cole added. “Changes in the hydrologic cycle also lead to issues like damage to infrastructure: floods that wipe out homes, highways or railroads; or to health effects, such as diseases like cholera.

“We believe global warming is supercharging El Niño,” Cole continued. “And if that's true, then we expect stronger climate extremes that will amplify ecological, infrastructural and human losses. No country has the resources to be fully protected from these impacts. This is one more reason we need to move away from fossil fuels, the root cause of the problem.”

The findings were supported by the U.S. National Science Foundation and the United Kingdom Natural Environmental Research Council. The Galápagos National Park and the Charles Darwin Research Station in Galápagos also provided support for the research.

The study’s co-authors include U-M researchers Kelsey Dyez, Cameron Tripp, Jonathan Overpeck and alumnus Jake Okun; University of Arizona researchers Diane Thompson and Marcus Lofverstrom; University of Edinburgh researcher Sandy Tudhope; Colorado College researcher Allison Lawman; University of Illinois researcher Jessica Conroy; Gloria Jimenez of Moody's Risk Management Services; and University of Minnesota researcher R. Lawrence Edwards.

This story was adapted for The Current from a release by Morgan Sherburne at the University of Michigan.

Journal

Science

DOI

10.1126/science.ady2660

Article Title

Recent strengthening of eastern Pacific ENSO in the last millennium paleorecord

Article Publication Date

27-Aug-2026