Explore the latest insights from top science journals in the Muser Press daily roundup (September 11, 2025), featuring impactful research on climate change challenges.
In brief:
Study finds extreme weather changes who migrates, not just how many
When severe heat waves, droughts, and other weather-related disasters strike, age and education shape who migrates and who stays put, according to a study published in Nature Communications.
The study describes how extreme weather can push some groups to move across borders and trap many others in place. These results contrast with mass migration scenarios often invoked in public debates about climate change.
“Weather extremes can both incentivize people to move away and increase the number of people who don’t have the ability to migrate,” said study author Hélène Benveniste, an assistant professor of environmental social sciences at the Stanford Doerr School of Sustainability. “Our research shows that migration in response to weather, just like migration decisions in general, is highly dependent upon demographic characteristics.”
The new analysis helps to resolve contradictory findings from past research. Some earlier studies, for example, have found mixed signals of whether men or women, or people with more or less education, are more likely to migrate following extreme heat.
Together with co-authors Peter Huybers of Harvard University and Jonathan Proctor of the University of British Columbia, Benveniste found that these conflicting outcomes often reflect global patterns shaped by local climate and the demographics of potential migrants.
‘Double penalty’
The researchers analyzed more than 125,000 cases of cross-border migration from 168 origin countries to 23 destinations, and over 480,000 within-country moves in 71 nations. Each move was classified by the migrant’s age, education level, sex, origin location, and destination, producing 32 different demographic groups. The team then mapped this dataset to daily records of temperature and soil moisture, which are closely tied to food security, livelihoods, and well-being.
By accounting for demographic differences, the new model predicts migration patterns up to 12 times better for cross-border flows and five times better for movement within countries than previous models that assumed everyone responds to weather shocks the same way. Still, weather itself accounts for no more than 1% of historical changes in international migration, the study found, because migration decisions are driven by multiple other factors besides weather.
Following periods of high heat, the analysis shows, children younger than 15 become less likely to migrate to a new country, while adults with little education become likelier to move away – especially those over 45. Cross-border migration rates of adults with education beyond high school, meanwhile, are little affected by weather.
“Our results indicate that many among those most likely to suffer from climate change impacts will not be able to get out of harm’s way,” the authors write. This creates a “double penalty,” whereby the people with the least resources to adapt in place also lose access to migration as a viable adaptation strategy as the world warms.
Escaping high heat
Baseline climate conditions appear to play a larger role in shaping moves within countries. “The effects of weather stress on people’s decision to relocate within their own country depend more on local climate zones, as well as demographics,” Benveniste said.
For example, adults with higher education living in tropical areas become more likely to relocate within their own countries when temperatures rise. The authors found a single day above 102 degrees Fahrenheit (about 39 °C) in a tropical zone where the baseline temperature is around 86 °F (30 °C) correlates with a roughly 0.5% bump in within-country migration rates among people with higher education, but no effect among those with little education beyond grade school.
In areas that are normally dry and hot, the researchers found unusually severe dry spells increase within-country migration, particularly among the least educated.
No evidence for mass border surges
Projecting forward under a scenario where Earth’s average temperature rises beyond 2.1 degrees Celsius above pre-industrial levels, the study estimates migration rates by 2100 could rise by about a quarter among older, less educated adults and fall by as much as a third among the youngest and least educated. These demographic-specific swings are much larger than the 1-5% changes seen when looking only at population averages.
To single out the effect of weather and climate, the authors assumed other migration drivers like conflict, politics, and job opportunities remain fixed. This approach is designed to show “how climate stress will change who is able to move and who is left behind, not to predict the number of people that will move in future decades,” Benveniste explained.
Actual future migration will depend on a broad array of social, economic, and policy factors – including nascent efforts to help populations thrive in place or improve their ability to move. “We hope that policymakers use these results as a basis to more squarely address the needs of different demographic groups,” Benveniste said. “We need to answer the needs not just of the people who move, but also those who are moving less.”
Journal Reference:
Benveniste, H., Huybers, P. & Proctor, J., ‘Global climate migration is a story of who and not just how many’, Nature Communications 16, 7752 (2025). DOI: 10.1038/s41467-025-62969-3
Article Source:
Press Release/Material by Stanford University
Wildfire ‘char’ may help suppress methane
It’s hard to believe that there is anything positive that could come out of wildfires. They have devastated homes, taken lives, erased memories, leveled cities and destroyed our forests and wildlands. But a University of Delaware professor has found that there is something of value to be learned from what’s left behind in the remnants.
The charred debris left in the wake of wildfires, such as those currently burning in Colorado, Canada and Arizona’s Grand Canyon National Park, is known as wildfire char. UD’s Pei Chiu, professor of civil, construction and environmental engineering, studies wildfire chars and the ways they just might prove useful in reducing methane, a powerful gas that traps heat in the atmosphere. Methane emissions come from many different sources, ranging from livestock manure to landfills and wastewater treatment plants.
This work also informs his research on biochar – man-made chars created from leftover wood chips, rice husks, corn stover and other agricultural biomass – that can be used in soil amendments, stormwater treatment and other applications.
Below, Chiu shares five important facts about char – both natural (wildfire char) and manmade (biochar). He also discusses his team’s recently published research in Environmental Science and Technology, a peer-reviewed journal of the American Chemical Society, detailing the potential of wildfire chars to suppress methane produced by microorganisms.
Co-authors on the paper include UD doctoral student Jiwon Choi and Danhui Xin, a former graduate student in Chiu’s lab, now at Southern California Coastal Water Research Project.
Q: What is char and where is it found?
Chiu: Char is a carbon-rich material formed at high temperature. In nature, chars are produced through wildfires (i.e., wildfire chars). Biochar, or manmade char, can be produced in a laboratory or commercially by heating surplus biomass, such as wood chips, leftover corn stalks or other crop residues at high temperatures in an oxygen-limited environment, through a process called pyrolysis. In agriculture, biochar is commonly used as a soil amendment to improve soil quality and productivity. It also can be incorporated into compost and filtration systems, among other uses.
Q: Why are you studying char?
Chiu: We discovered a few years ago that heating up plant biomass through pyrolysis can create a large capacity in biochar to reversibly accept and donate electrons. This capacity, called electron storage capacity, plays a key role in biological metabolism. When you run, for example, electrons are exchanged between sugar molecules in the body and the oxygen you breathe to create energy. If you need energy faster than you can take oxygen in, the body ferments the sugars for energy instead.
Microbes do the same thing. When there is no oxygen for microbes to breathe (exchange electrons with), fermenting microbes take over. This often leads to products we don’t want, like methane, in landfills, cattle, wetlands, rice paddies, waste digesters, swamps and other oxygen-depleted environments. Our recent work shows that all chars can serve as oxygen for microbes to breathe and grow, allowing good bacteria to outcompete fermenting microbes called methanogens that produce over 50% of the global methane, and suppressing methane formation in the process.
Q: What does this have to do with wildfires?
Chiu: Wildfire chars have been part of the global carbon cycle for millions of years. We hypothesized that microorganisms must have evolved the ability to metabolize, or process, chars. If true, this novel biological role of chars would have many important implications and applications in biogeochemistry, global climate, contaminant fate and environmental cleanup. While this benefit will never outweigh the detrimental effects of wildfires, both human and environmental, it is something we can learn from and leverage in our effort to mitigate the impact of greenhouse gases.
Q: What has your latest work shown?
Chiu: My group recently published a paper, showing that all chars have a significant electron storage capacity (ESC). For example, wildfire chars and biochars can store a few billion trillion electrons in a gram (about a quarter teaspoon) of char. Agriculture in the United States generates approximately 140 million dry tons of crop residues every year. Corn stover and wheat straw are the main contributors. In addition, forestry generates between 60-70 million dry tons of biomass annually. So, that’s a lot of storage capacity. Meanwhile, common soil microbes can grow by respiring or “breathing” char for energy, something they have likely been doing for eons without us knowing.
Q: Why is this important?
Chiu: All wildfire chars and plant-based biochars can suppress methane. By supporting the growth of char-breathing bacteria, wildfire chars enable these microbes to outcompete methanogens. This is important because methanogens produce over 50% of the global methane today, a major greenhouse gas that is 85 times more potent than carbon dioxide and contributes to over 30% of the current warming. Enlisting microbes with the ability to breathe chars to help us combat this challenge is both smart and sustainable – since these microbes are common in nature and can use the same char repeatedly to suppress methane production again and again.
Microbes with the ability to use char for energy can do other things, too, like prevent arsenic from entering drinking water and food crops, and remove pollutants such as nitrate and perchlorate, from stormwater and groundwater.
Q: What keeps you passionate about this research?
Chiu: What really motivates me is the science. Chars collectively represent an enormous rechargeable and bioavailable reservoir of nearly a trillion-trillion-trillion electrons that we inject into the global biogeochemical cycle every single year. Never heard of a trillion-trillion-trillion? It’s a one, followed by 36 zeros. We did not know this until now, but microbes have been eating and breathing chars for hundreds of millions of years. But how? How do they eat or breathe a piece of solid – repeatedly?
Globally, the research community has focused for a long time on reducing carbon dioxide from the environment. Carbon dioxide stays in the environment for anywhere from 50 to 200 years, so if today’s solutions are successful, my great-great-grandchildren will benefit. Methane is 85 times more potent than carbon dioxide, and its lifespan in the environment is only 11.8 years. If we can find ways to reduce methane in the environment, I could live to see the impact in my lifetime.
Journal Reference:
Jiwon Choi, Danhui Xin, and Pei C. Chiu, ‘A New Climate Impact of Wildfire Chars: Suppression of Biogenic Methane Production Over Repeated Redox Cycles’, Environmental Science & Technology 59, 31, 16443–16451 (2025). DOI: 10.1021/acs.est.5c05709
Article Source:
Press Release/Material by Karen B. Roberts | University of Delaware
New research shows changing winters will hit northern lakes the hardest
In the world’s cold and snowy regions, shorter and warmer winters are one of the most conspicuous consequences of climate change. For freshwater lakes, this means later freezing, earlier thawing, and thinner ice. A new study, published in Ecology Letters, shows that the ecological impacts of these winter changes may be most dramatic in high-latitude lakes.
“The ecology of ice-covered lakes is a bit of a black box for lake scientists,” said Ted Ozersky, a University of Minnesota Duluth biologist who led the research. “For a long time, we assumed that nothing interesting happened under the ice, so few studies looked at what goes on in frozen lakes.” But as ice cover declines, the winter ecology of lakes is gaining attention – and urgency.
A key question scientists are now asking is: how will lakes respond to shorter, warmer winters and less ice?
The new paper, authored by researchers from the United States, Norway and Canada, shows that changes in winter ice and snow conditions will have the greatest ecological impact on Arctic lakes, followed by those in boreal and temperate areas. The reason lies in a previously unrecognized interaction between the timing of incoming solar radiation and the seasonality of ice cover.
At high latitudes, a larger share of the sun’s annual light arrives while lakes are still frozen. For example, at 75°N, more than half the year’s solar energy reaches the Earth’s surface during the lake ice-covered period. At 45°N, that figure is closer to 25 percent. As a result, even small changes in the duration or transparency of lake ice can dramatically alter how much light reaches the water column at high latitudes.
“Here in northern Norway and in other Arctic regions, many lakes are still frozen well-into the midnight sun period, experiencing 24-hours of daylight,” said co-author Amanda Poste of the Norwegian Institute for Nature Research. “In these Arctic lakes, under-ice production can contribute substantially to lake food webs, which could be threatened by predicted increases in snow cover in some regions. On the other hand, loss of ice during a period with around-the-clock daylight could lead to increased open water productivity.”
The team combined models of incoming sunlight with realistic snow and ice cover scenarios across a range of latitudes. They also explored how light interacts with temperature in lakes at different latitudes. Because light and temperature are key drivers of biological productivity, understanding how these factors are changing is essential for predicting shifts in lake food webs and ecosystem functioning.
Key findings from the study include:
Light availability in high-latitude lakes is far more sensitive to changes in ice and snow conditions than in temperate lakes.
Climate change is increasing the seasonal overlap of light and warmth, especially at high latitudes, thus enhancing the potential for plant growth and animal activity.
As a result, high-latitude lakes may undergo more dramatic ecological shifts, including changes in productivity, food web dynamics and the timing of biological events.
The paper offers a new framework for understanding how climate change will affect lake ecosystems and lays out testable predictions for future research.
“Many researchers who are starting to study frozen lakes focus on just one region,” said Ozersky. “Our collaboration includes researchers working on lakes in very different locations, from Minnesota to boreal Québec to the high Arctic. By working together we were able to identify this interesting large-scale pattern.”
The study underscores that winter plays a key role in shaping lake ecosystems, and that changes that happen during the ice cover period can have powerful and lasting effects, especially in northern lakes. The authors are now working with dozens of research groups around the world to collect standardized observations from diverse ice-covered lakes to test and refine the model’s predictions.
Journal Reference:
Ozersky, T., A. Poste, M. Rautio, and E. Leu, ‘Impacts of Changing Winters on Lake Ecosystems Will Increase With Latitude’, Ecology Letters 28, 8: e70200 (2025). DOI: 10.1111/ele.70200
Article Source:
Press Release/Material by University of Minnesota
The long legacy of human-driven ant decline in Fiji
A new study of ants in Fiji – involving genomic sequencing of over 4,000 ant specimens from museum collections – shows that most native species have been in decline since humans first arrived in the archipelago 3,000 years ago. Meanwhile, recently introduced ant species have expanded. The findings underscore how human activity has and continues to reshape fragile island ecosystems.
Insects, which make up much of Earth’s biodiversity, provide crucial ecosystem services, including pollination, soil health, and natural pest control. Recent reports of dramatic declines in insect abundance and diversity – sometimes referred to as the “insect apocalypse” – have raised global concern. Although factors such as habitat destruction, agricultural intensification, climate change, pesticide use, and light pollution are frequently implicated, the scale and universality of these declines remain debated because most studies rely on relatively short-term data or historical collections spanning only decades to centuries, leaving long-term trends largely unexplored.
Advances in genomic techniques now allow scientists to reconstruct historical population trends over thousands of years, however, providing insight into how both recent and ancient human activities have shaped insect communities.
Here, Cong Liu and colleagues examined long-term trends in abundance, diversity, and ecological roles of ants in the Fijian archipelago. Ants – abundant and functionally important – serve as indicators of broader biodiversity patterns, making them ideal for such studies. And islands like Fiji, with high numbers of endemic species, are especially vulnerable to human impacts. Liu et al. applied a community genomics approach, which used high-throughput genomic sequencing on over 4,000 ant specimens from Fijian museum collections, to estimate long-term community assembly and demographic trends of ants on the islands.
Fiji’s ant fauna was shaped by at least 65 colonization events, they say. Some arrived millions of years ago, which led to endemic Fijian species. Regional Pacific colonizations also impacted Fiji’s ant fauna, as did more modern introductions of ant species by humans through global trade. Notably, population modeling revealed stark differences between endemic and non-endemic species.
About 79% of endemic ants – mostly confined to high-elevation, intact forests – have declined, with reductions beginning after humans first settled Fiji ~3,000 years ago and accelerating in the past 300 years alongside European contact, industrial agriculture, and species introductions. In contrast, widespread Pacific species and recent human-introduced invasive ants, which are more tolerant or adapted to human-dominant habitats, have generally expanded their populations, particularly in disturbed lowland habitats. These divergent trajectories reflect how ecological traits, habitat preference, and biogeographic context determine which species “win or lose” in the Anthropocene, Liu et al. say.
Journal Reference:
Cong Liu, Eli Sarnat, Jo Ann Tan, Julia Janicki, John Deyrup, Masako Ogasawara et al., ‘Genomic signatures indicate biodiversity loss in an endemic island ant fauna’, Science 389, 389, pp. 1133-1136 (2025). DOI: 10.1126/science.ads3004
Article Source:
Press Release/Material by Walter Beckwith | American Association for the Advancement of Science (AAAS)
Featured image credit: Gerd Altmann | Pixabay
