The future fate of water in the Andes

What if the ongoing 15-year megadrought hits Chile again at the end of the century?

Institute of Science and Technology Austria

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Tapado Glacier, an example of a glacier in the arid landscape of the Southern Andes, Chile. The sharp spikes of snow and ice are typical of dry mountain regions. Meltwater streams pour from the glacier. This type of meltwater is crucially important to the population during droughts.

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Credit: © Álvaro Ayala

In light of the ongoing fifteen-year megadrought in Chile, an international team of researchers, including Francesca Pellicciotti from the Institute of Science and Technology Austria (ISTA), addressed a bold future scenario. Their findings: by the end of the century, the considerably worn-out glaciers will not be able to buffer a similar megadrought. They call for coordinated global climate policies to develop effective water management strategies. The results were published in Communications Earth & Environment.

Could a drought have no end? Fifteen years of severe and persistent drought in Chile have already passed, and the country seems left to bleed dry of its precious water resources. As surprising as this may sound, no one saw this coming. “Climate scientists only realized in 2015 that the unending drought in Chile was really a big thing,” says Francesca Pellicciotti, Professor at the Institute of Science and Technology Austria (ISTA). “The Chilean megadrought was never forecast in any climate model. The existing models even showed absurd likelihoods for such an extreme event. And yet, it has happened and is still ongoing.” In light of this evidence, a question emerges: Are we prepared for future climate disasters?

Now, Pellicciotti, together with Álvaro Ayala and Eduardo Muñoz-Castro, two Chilean Earth scientists now based at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, sought to address this problem. With a team of international researchers, they modeled an audacious future scenario based on the ongoing Chilean megadrought. At the center of their analysis are glaciers in the Southern Andes, the majestic ‘water towers’ that are currently buffering the ongoing megadrought at the cost of their own survival.

‘Chile 2.0’ megadrought by 2100?

With the Atacama Desert in the north, Chile’s semiarid central region depends on snow for its water security. During droughts, glacier meltwater comes to the rescue. According to Ayala, Chileans were accustomed to recurrent droughts every five to six years, which would typically last for one or two years. “During the first few years of the current megadrought, people in Chile remained hopeful that things would improve the following year, and again the year after,” he says. But disillusionment would follow soon.

Perhaps all it takes to understand megadroughts is a bolder scientific approach. “Álvaro asked an elegant question: ‘What would happen if a similar megadrought struck Chile at the end of the century?’,” says Pellicciotti. “This simple, yet very clever question led to some really cool results.”

Half of today’s summer meltwater resources

In their model, the team focused on the 100 largest glaciers in the southern Andes (Central Chile and Argentina), accounting for seasonal snow and rain. They started by modeling 10 years before the onset of the drought and 10 years of megadrought. “We ensured we had a clear idea about the fate of glaciers, how much they lose mass, and what happens to the water,” says Ayala. “We then projected the model until the end of the 21st century, when the glaciers will be considerably smaller than now, and simulated a similar megadrought under these conditions.”

The scientists demonstrated that, in such a scenario, what will be left of the largest 100 glaciers in the Southern Andes will only be able to contribute half of today’s runoff meltwater during the dry summer months. For the smaller glaciers in the region, which were not included in this work, the situation might be even more dramatic. “The smaller glaciers will likely have disappeared by then, and a future ‘Chile 2.0’ megadrought will very likely be a severe blow for their ecosystems,” explains Ayala.

Megadroughts as the new normal?

Are these results realistic, considering that we did not even foresee the current megadrought in Chile? “There is a consensus that general models underestimate extremes,” says Pellicciotti. A recurrent pattern is that amid the general trend of global warming, episodic droughts occur as discrete severe events on a gradually worsening baseline, accompanied by continuous glacier mass loss. But while droughts are regular, megadroughts are quite unprecedented. “In projections that consider very severe scenarios, we can indeed see megadroughts. However, in more moderate scenarios, the precipitation patterns are more similar to those we are experiencing today,” says Pellicciotti. “So, there must be something else that we don’t see in the models.”

Recently, Pellicciotti was involved in another study that reanalyzed global data collected over 40 years, confirming that multi-year extreme droughts will become more frequent, severe, and extensive. While this might forebode an age of megadroughts, scientists underline that it is still difficult to define them in the first place. Currently, megadroughts are labeled as such through their impact on vegetation. Even more strikingly, it becomes apparent during annual geosciences meetings that scientists still do not know what exactly causes megadroughts, Pellicciotti explains.

While the detailed mechanisms are still under investigation, researchers are increasingly warning that megadroughts have become the new normal and calling on policymakers to act accordingly. However, sometimes, the challenge remains to convince funding bodies of the need to research megadroughts on a global scale. “We started studying megadroughts in Europe because of the Chilean case,” says Pellicciotti. “However, reviewers were not always in favor of our efforts, arguing that there has been no megadrought in Europe since the Middle Ages. But then, a sequence of droughts hit Europe at an increasing frequency.”

Chile and Europe in one boat?

In Chile, the keyword “desertification” has become difficult to bypass. “We see this pattern slowly extending from the north toward the south. So, the deserts in the north likely show us today what central Chile might look like in the future,” says Ayala. “Similarly, in Europe, one can look at the Mediterranean mountains to understand the future of the Alps.”

In light of this, the researchers underline the need for coordinated global climate policies to develop effective water management strategies. While Chile has assigned priorities, Europe must still work with water managers to model scenarios on competing water uses and allocation programs. According to Pellicciotti, such scenarios must also account for megadroughts, meaning a system that is water-deficient from the start.

Thinking of their home country, Ayala and Muñoz-Castro also call for coordinated action. “We must be well prepared for what will come next, as we won’t be able to rely on all the factors that ‘worked’ until now during the current megadrought. We must be flexible enough with our water management plans to handle future situations without counting on the glacier’s contribution,” Ayala concludes.

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The present study was conducted by researchers in Chile (Center for Advanced Studies in Arid Zones CEAZA, La Serena; Department of Civil Engineering, Universidad de Chile; Department of Geography, Universidad de Concepción; Advanced Mining Technology Center AMTC, Universidad de Chile), Switzerland (Swiss Federal Institute for Forest, Snow and Landscape Research WSL; WSL Institute for Snow and Avalanche Research SLF; Climate Change, Extremes and Natural Hazards in Alpine Regions Research Center CERC; Institute for Atmospheric and Climate Science, ETH Zurich; Laboratory of Hydraulics, Hydrology and Glaciology VAW, ETH Zurich), New Zealand (Waterways Centre, University of Canterbury and Lincoln University), and Austria (Institute of Science and Technology Austria ISTA).

 

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Journal

Communications Earth & Environment

DOI

10.1038/s43247-025-02845-6 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Less water from glaciers during future megadroughts in the Southern Andes

Article Publication Date

18-Nov-2025

Universidad Glacier, one of the largest glaciers in central Chile. It will face major retreat and mass loss during the coming decades. 

Credit

© Álvaro Ayala

La Laguna Reservoir plays a key role in regulating water resources for agriculture and drinking in the Andes of north-central Chile. The inflow to the reservoir is driven by snow and ice melt. 

Credit

© David Farías-Barahona

Glaciological fieldwork on the top of Tapado Glacier.

Credit

© Daniel Thomas

Professor Francesca Pellicciotti leads the research group "Cryosphere and Mountain Hydrosphere" at the Institute of Science and Technology Austria (ISTA) in Klosterneuburg, just outside of the Austrian capital Vienna. 

Credit

© ISTA

 

‘Breathing’ robots reveal how fear spreads through touch

Universiteit van Amsterdam

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'Breathing' robot

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Credit: Zak Witkower / UvA

Humans can “catch” fear from robots, new research has shown. The findings – by a team of psychologists from the University of Amsterdam and the University of British Columbia – shed new light on how emotions can spread through touch, with implications for human relationships, mental health, and future technologies such as virtual reality and wearable devices. The research was published in the journal Emotion.

When people are frightened, they often grab a loved one’s hand, hug a pet, or cling to someone nearby. Touch is usually comforting – but not always. ‘If the person you’re holding is scared, their body might give you signals that increase your own fear,’ says lead researcher Dr Zachary Witkower of the UvA. ‘Our work shows that one of those signals is breathing.’

Breathing is closely tied to emotion: calm breathing suggests relaxation, while rapid breathing can signal fear or panic. The researchers wanted to know if people could sense these breathing changes through physical contact – and whether that would affect their own body’s response to fear.

Testing fear with a ‘breathing’ robot

To find out, the team designed a furry, plush robot with a hidden motorised ribcage that could mimic human breathing. More than 100 student volunteers hugged the robot while watching a scary movie clip. Depending on the group, the robot either: did not “breathe” at all; breathed steadily at a calm pace, or breathed rapidly, simulating hyperventilation. Meanwhile, the researchers tracked the volunteers’ heart rates to measure physiological arousal.

Fear is contagious – even from a machine

The results were striking. Participants holding the robot with rapid breathing showed the strongest increases in heart rate – indicating heightened fear – compared to those holding the calm-breathing or still robots. Importantly, the participants also judged the fast-breathing robot as appearing “afraid,” suggesting they interpreted the robot’s body signals the same way they would interpret a human or animal’s.

Applications in technology and therapy

The study has broad implications. For human-robot interaction, it suggests that machines simulating breathing could be used to influence users’ emotions – just as video game controllers use vibration to intensify excitement. In therapeutic contexts, calming robots or wearable devices might help people regulate stress or anxiety by guiding their physiological responses.

On the flip side, the findings also reveal a cautionary note: clinging to someone (or something) that is panicking may make you panic too. ‘People often cling to others when they’re scared, but if the other person is also afraid and hyperventilating, that touch can backfire by amplifying your own physiological response,’ Witkower says.

Future directions

The researchers emphasise that their study was conducted with university students in a controlled lab setting. Future work will explore whether similar effects occur in children, older adults, or people with anxiety disorders. The team also hopes to measure breathing directly, alongside heart rate, to better understand the biological mechanisms at play.

A window into emotional contagion

Overall, the findings highlight how subtle bodily signals –  like breathing – can spread emotions without words. ‘We often think of emotions as spreading through facial expressions or tone of voice,’ Witkower says. ‘But our study shows that something as basic as the rhythm of another’s breathing, even when simulated by a robot, can affect how our own bodies respond to fear.’

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Journal

Emotion

DOI

10.1037/emo0001601 

Article Title

Human psychophysiology is influenced by physical touch with a “breathing” robot

 

Ancient and colonial legacies still shaping the Amazon’s forests

Universiteit van Amsterdam

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Human influence across centuries continues to define biodiversity and carbon storage in the world’s largest rainforest, according to a new collaborative and international study led by the University of Amsterdam. The study shows that the Amazon rainforest – often described as one of the last untouched wildernesses – still bears the deep ecological imprints of both pre-Columbian Indigenous communities and European colonists. The study was published on 17 November in the journal PNAS.

Using cutting-edge spatial modeling and vast historical datasets, the researchers discovered that centuries of human settlement, cultivation, and resource extraction have left lasting marks on the distribution of Amazonian tree species, many of which remain visible today.

‘Our findings show that seemingly undisturbed parts of the Amazon forest have been shaped by people over hundreds or even thousands of years,’ says Crystal McMichael, the study’s lead author. ‘These invisible legacies may still be affecting both ecosystem functioning and biodiversity.’

Ancient roots, lasting impacts

The research team combined data from over 7,000 archaeological sites with more than 100,000 digitised biodiversity records dating back to the early European expeditions. By modeling human settlement patterns during the pre-Columbian era (before European contact) and the colonial era (1600–1920 CE, including the Amazon Rubber Boom), they mapped where human activity was most intense. These historical models were compared with tree data from 1,521 forest plots across the Amazon basin, representing 262 dominant and useful species.

In contrast, other trees – such as certain palms and hardwoods used in colonial construction –appear to have declined in regions that experienced heavy exploitation during the colonial and Rubber Boom periods.

‘Indigenous communities tended to actively manage forests and alter the balance of different species over time,’ says Hans ter Steege of Naturalis Biodiversity Center. ‘Later colonial industries often extracted resources more intensively, leaving behind ecological scars that are still healing.’

A living legacy for conservation

The study challenges the long-held idea that most Amazonian forests are purely “natural” systems untouched by human hands. But it also challenges the recent ideas that only the pre-Columbian inhabitants of Amazonia shaped the forest. Instead, they are living mosaics of ecological and cultural history that have been written and rewritten over centuries to millennia.

The researchers argue that recognising these legacies is crucial for improving conservation and climate models, which often assume that old-growth forests have remained undisturbed for millennia.

Ultimately, the research reframes parts of the Amazon as a dynamic system of coexistence between people and nature – an evolving landscape that has been cultivated, abandoned, and reborn many times over.

‘To protect the Amazon’s future, we must first understand its past,’ says McMichael. ‘Accounting for ancient and colonial legacies can help us better predict how forests will respond to deforestation, climate change, and reforestation efforts.’

The results were clear: both Indigenous and colonial populations tended to settle along major rivers, where fertile soils and access to trade routes supported larger communities. Even today, forests within about 10 km of these rivers show higher abundances of tree species favored by humans.

‘Rivers have always been lifelines in the Amazon,’ says co-author Mark Bush of the Florida Institute of Technology. ‘They shaped how people moved, lived, and interacted with the forest – and that history is still being written into the ecosystem.’

Enrichment and depletion

The study found that human activity enriched the forest with many useful and now-iconic species. Trees such as the Brazil nut (Bertholettia excelsa), rubber tree (Hevea brasiliensis), and the murumuru palm (Astrocaryum murumuru) all flourished in areas with a long history of human presence. These species remain among the Amazon’s most economically and ecologically important today.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2514040122 

 

Weather behind past heat waves could return far deadlier

Weather patterns that produced five severe heat waves in Europe over the past 30 years could kill thousands more people if repeated in today’s hotter global climate, a new study finds. Acceleration of efforts to adapt to greater extremes could save live

Stanford University

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The weather patterns that produced some of Europe’s most extreme heat waves over the past three decades could prove far more lethal if they strike in today’s hotter climate, pushing weekly deaths toward levels seen during the COVID pandemic, according to a November 18 study in Nature Climate Change.

“We showed that if these same weather systems were to occur after we’ve trapped a lot more heat in the atmosphere with greenhouse gases, the intensity of the heat waves gets stronger and the death toll rises,” said lead study author Christopher Callahan, who completed the research as a Stanford Doerr School of Sustainability postdoctoral scholar and recently joined the Indiana University faculty.

Global average temperatures in recent years have approached 1.5 degrees Celsius above pre-industrial levels and about 0.7 degrees above the 2003 average, when a heat wave killed more than 20,000 people across Europe. This year, 2025, researchers estimated thousands of people may have lost their lives because of extreme heat during the fourth-hottest summer in European history. 

Using a combination of artificial intelligence and statistical techniques from economics, Callahan and colleagues estimate that 2003-like weather patterns could cause 17,800 excess deaths across the continent in a single week against the backdrop of today’s climate, compared to 9,000 with no global warming. At 3 degrees Celsius above pre-industrial levels, their modeling shows weekly excess deaths from a 2003-like weather system could reach 32,000. 

Recipe for disaster

Deadly heat waves in Europe have repeatedly followed the stalling of a high-pressure system, or “heat dome,” over land already parched from months of low rainfall. 

In the summer of 2003, an extreme version of this combination held temperatures around 38 degrees Celsius (100 degrees Fahrenheit) for two weeks straight across much of Western Europe. In France, refrigerated trucks stored bodies as morgues reached capacity. The temperatures were so extreme that the event essentially broke conventional probability calculations, which suggested that without climate change it might be a one-in-a-million-year event.

“That event, which was devastating from a health point of view, was extremely statistically rare at the time that it happened, and yet we know it’s possible the weather conditions that produced it could happen again, but in what is now a much warmer climate,” said co-author Noah Diffenbaugh, the William Wrigley Professor in the Stanford Doerr School of Sustainability. 

Until now, however, researchers have not known the likely death toll if those same weather conditions arise in the current climate two decades later, or in the future after additional global warming.

Exponential risk

Scientists have known for decades that extreme heat waves can be expected to intensify as the planet continues to warm, and growing evidence shows that heat-related mortality risks can increase exponentially as it gets hotter. The new study shows how this could play out in Europe. “These events could be as bad as some of the worst weeks of COVID by mid-century” said co-author Marshall Burke, a Stanford professor of environmental social sciences.

The researchers used statistical and machine learning methods, including a model developed by co-author Jared Trok, a PhD student in Diffenbaugh’s group at Stanford. 

They incorporated meteorological data, daily surface temperatures, and death records from 924 subnational regions of Europe during five major heat waves between 1994 and 2023, as well as global average temperatures during the 12 months preceding each heat event. The wide range of human influence on the climate during this period, from 0.5 to 1.3 degrees Celsius above the pre-industrial baseline, enabled the researchers to examine a spectrum of possible heat wave conditions.

Like previous studies, the research shows mortality risks depend on the temperatures that a given location is accustomed to, with warmer locations somewhat less sensitive to hot temperatures than cooler regions.  

“We don’t compare Paris to Amsterdam, but instead compare Paris to itself during the really bad August heat wave of 2003 and the normal August of 2002,” Burke explained. “That allows us to isolate the impact of heat from all the other things that could affect mortality either over time or across places.”

The data show a steep rise in deaths after a day around 30 degrees Celsius (86 degrees Fahrenheit) in even the warmest regions, “potentially reflecting limits to adaptation to the hottest conditions,” the authors write. 

‘We are just so underprepared’

Overall, if future societies continue to adapt as they have in recent decades, the authors estimate adjustments to hotter temperatures could prevent only about one in ten of the deaths otherwise expected from extreme heat.

Although more research is needed to understand which interventions are most effective, measures such as expanding access to air conditioning and shade, retrofitting homes and schools to increase ventilation, and establishing programs to check on isolated people may help to save lives. “If novel or faster adaptations emerge, these death tolls could be reduced more,” Callahan said.

Hospitals and health systems can prepare by building capacity for the types of plausible high-impact scenarios detailed in the new paper, rather than planning based on average temperature projections. 

“A lot of the reason for excess deaths is because we are just so underprepared for these events. Similar to during COVID when the health system was just fully disrupted, people can’t get to the hospital, hospitals have to discharge people early,” Burke said. “So, even if you have something bad happen to you that’s not related to heat at all, your care is going to suffer and health outcomes will worsen.” 

Diffenbaugh said the results underscore a need to prepare for bigger extremes now. Individual years with global temperatures reaching 1.5 degrees Celsius above pre-industrial levels are already happening, and the weather that can turn those years deadly is not hypothetical. “There are a lot of reasons to be skeptical about future climate projections, but we can at least be prepared in the event that the kinds of weather conditions we’ve already experienced occur again but in a warmer climate,” he said.

 

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Study co-authors not mentioned above include Andrew Wilson, Carlos Gould, and Sam Heft-Neal. Wilson is a postdoctoral scholar at Stanford’s Center on Food Security and the Environment. Heft-Neal is a senior research scholar at the Center on Food Security and the Environment and Burke’s Environmental Change and Human Outcomes (ECHO) lab. Gould, a former Stanford Earth Postdoctoral Fellow, is an assistant professor at the University of California, San Diego, in the School of Public Health. 

Burke is also a senior fellow at the Freeman Spogli Institute for International Studies, the Stanford Institute for Economic Policy Research, and the Woods Institute for the Environment. Diffenbaugh is also a professor of Earth system science in the Doerr School of Sustainability and the Kimmelman Family Senior Fellow at the Woods Institute for the Environment. The study was supported by Stanford University.

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Journal

Nature Climate Change

DOI

10.1038/s41558-025-02480-1 

Article Title

Increasing risk of mass human heat mortality if historical weather patterns recur

Article Publication Date

18-Nov-2025