Feed aggregator

University of Alberta geochemists have discovered a missing piece to one of the great mysteries of science—the origin of life on Earth.

A new review has revealed that the Southern Annular Mode (SAM), the Southern Hemisphere's most influential climate driver, is now in its most positive state in more than 1,000 years. If greenhouse gas emissions continue to rise, this positive state is projected to persist throughout the 21st century, with long-term implications for Antarctica and the Southern Ocean.

Two new publications remap the understanding of reverse weathering in the scientific community. The Dauphin Island Sea Lab's Senior Marine Scientist, Dr. Jeffrey Krause, played a key role in both projects, which include several collaborating institutions.

Since 2020, the Barry Landslide in Alaska's Prince William Sound has been outfitted with instruments monitoring seismic signals from the area, as researchers hope to catch a destructive, tsunami-generating landslide before it starts.

The Serengeti is one of the most diverse ecosystems on Earth. The massive savanna stretches more than 30,000 square kilometers across Tanzania and southwestern Kenya, and conservation sites, including national parks and a United Nations Educational, Scientific and Cultural Organization World Heritage Site, mark its significance as one of the world’s last intact large-animal migration corridors.

Life in the Serengeti is shaped by interactions between herbivores, vegetation, fire, and rain. Every year, millions of wildebeest, zebras, and gazelles hoof it across the savanna for their great migration, an 800-kilometer loop through the Serengeti and Kenya’s adjacent Maasai Mara game reserve. The iconic migration is dictated by rainfall, with herbivores following the green grass brought by the rainy season.

New research documenting the far-reaching impact of increasing rainfall on the Serengeti will be presented on Monday, 15 December, at AGU’s Annual Meeting. Megan Donaldson, a postdoctoral researcher at Duke University’s Nicholas School of the Environment, and her colleagues will share how vegetation is consumed by both grazing herbivores and fire in the Serengeti and how that consumption is reflected in the landscape. Studies like Donaldson’s are emerging as an important area of research for scientists assessing how climate change will affect the closely intertwined biotic and abiotic components in tropical grassland ecosystems around the world.

“For now, we’re just looking at how those interactions are feeding back to each other, how increased rainfall is affecting the dynamics between vegetation, herbivores, and fire,” said Donaldson.

Rainfall, Fuel, and Food

Rainfall controls how much grass grows in the Serengeti: When rainfall is intense, grasses grow quickly.

That growth is consumed in two primary ways: by fire as fuel and by herbivores as food.

Fire can eradicate excess vegetation, which is why a previous rainy season in the Serengeti might be a reliable predictor for how much land will burn there in the near future.

More than 30 species of large herbivores consume vegetation in the Serengeti, each with its own ecological niche.

“Some are constantly on the move, others are residents, some are grazers, some browsers, others are mixed feeders, and they range in size from the minuscule dik-dik to the massive elephant. They all thrive together by seeking out seasonal sources of water and feeding differentially on the rich diversity and abundance of grasses, shrubs, and trees,” said Monica Bond, a wildlife biologist at the University of Zurich who was not part of the recent study.

Herbivores consume vegetation at a much slower rate than fire does. Under normal conditions, grazing herbivores keep grass levels low enough to reduce the spread of fire across large areas. But it can take several seasons for animal populations to adjust to differences in food availability, so as rainfall totals increase and cause explosive growth in savanna vegetation, herbivores are unable to maintain their ability to minimize the fuel available for wildfires.

In the new research, Donaldson and her colleagues examined weather station and camera trap data from sites inside Serengeti National Park in Tanzania.

In particular, the researchers tracked how recent shifts in the Indian Ocean Dipole caused rainfall totals to increase across the Serengeti. The Indian Ocean Dipole is a weather pattern similar to the El Niño–Southern Oscillation phenomenon that spawns El Niño or La Niña conditions in the Pacific. It alters wind, rain, and temperature conditions in East Africa. Between 2019 and 2024, mean rainfall totals in the Serengeti were 268 millimeters higher than in the period from 1999 through 2003.

The researchers found that within the park, rainfall was not uniform. “There’s a rainfall gradient. You get low rainfall in the south and high rainfall in the north,” said Donaldson.

In the northern Serengeti, surplus rainfall supported such rapid growth of grass that herbivore consumption had little influence on reducing the amount of fuel available for wildfires.

In the typically drier south, however, herbivores were able to keep grasses short enough to slow the buildup of fuel.

But during periods of increased rainfall, Donaldson explained, “we see that those feedbacks are quicker. You’re getting fuel buildup much quicker, and you need all the [animal] migrants to come through that system to have any effect on fire.”

Untangling a Complex Ecosystem

Between 2019 and 2024, fire size in the Serengeti increased, but the increase was more complex than “more fuel feeding more fires.”

“The number of fires necessarily isn’t changing; it seems to be staying stable,” explained Donaldson. “We’re not seeing this very strong correlation between increased rainfall and increased fire. What is driving that? Why are we seeing that? And what are herbivores doing to that? Those are the things we’re trying to tease apart right now.”

“Because the Serengeti is one of the few intact biologically functioning ecosystems left on the planet, it makes for a perfect natural laboratory.”

Future work from Donaldson and her colleagues will further researchers’ understanding of how the Serengeti’s four major players—herbivores, biomass, fire, and rainfall—connect.

“Because the Serengeti is one of the few intact biologically functioning ecosystems left on the planet, it makes for a perfect natural laboratory to study complex ecological interactions and how these are affected by climate change,” said Bond. “This research has important implications for fire management and thus for wildlife conservation in this ecologically critical landscape. It is incredible the research that they have done here in fostering understanding of how this system works.”

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Tracing fire, rain, and herbivores in the Serengeti, Eos, 106, https://doi.org/10.1029/2025EO250444. Published on 2 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Our Sun is about halfway through its life, which means Earth is as well. After a star exhausts its hydrogen nuclear fuel, its diameter expands more than a hundredfold, engulfing any unlucky planets in close orbits. That day is at least 5 billion years off for our solar system, but scientists have spotted a possible preview of our world’s fate.

Elderly stars just get hungry.

Using data from the TESS (Transiting Exoplanet Survey Satellite) observatory, astronomers Edward Bryant of the University of Warwick and Vincent Van Eylen of University College London compared systems with stars in the main sequence of their lifetimes—fusing hydrogen, like the Sun—with post–main sequence stars closer to the end of their lifetimes, both with and without planets.

“We saw that these planets are getting rarer [as stars age],” Bryant said. In other words, planets are disappearing as their host stars grow old. The comparison between planetary systems with younger and older stars makes it clear that the discrepancy does not stem from the fact that the planets weren’t there in the first place: Elderly stars just get hungry.

“We’re fairly confident that it’s not due to a formation effect,” Bryant explained, “because we don’t see large differences in the mass and [chemical composition] of these stars versus the main sequence star populations.”

Complete engulfment isn’t the only way giant stars can obliterate planets. As they grow, giant stars also exert increasingly larger tidal forces on their satellites that make their orbits decay, strip them of their atmospheres, and can even tear them apart completely. The orbital decay aspect is potentially measurable, and this is the effect Bryant and Van Eylen considered in their model for how planets die.

“We’re looking at how common planets are around different types of stars, with number of planets per star,” Bryant said. Bryant and Van Eylen identified 456,941 post–main sequence stars in TESS data and, from those, found 130 planets and planet candidates with close-in orbits. “The fraction [of stars with planets] gets significantly lower for all stars and shorter-period planets, which is very much in line with the predictions from the theory that tidal decay becomes very strong as these stars evolved.”

Astronomers use TESS to find exoplanets by looking for the diminishment in light as they pass in front of their host stars, a miniature eclipse known as a transit. As with any exoplanet detection method, transits are best suited to large, Jupiter-sized planets in relatively small orbits lasting less than half of an Earth year, sometimes much less. So these solar systems aren’t much like ours in that respect. Studying planets orbiting post–main sequence stars poses additional challenges.

“If you have the same size planet but a larger star, you have a smaller transit,” Bryant said. “That makes it harder to find these systems because the signals are much shallower.”

However, though the stars in the sample data have a much greater surface area, they are comparable in mass to the Sun, and that’s what matters most, the researchers said. A star with the same mass as the Sun will go through the same life stages and die the same way, and that similarity is what helps reveal our solar system’s future.

“The processes that take place once the star evolves [past main sequence] can tell us about the interaction between planets and host star,” said Sabine Reffert, an astronomer at Universität Heidelberg who was not involved in the study. “We had never seen this kind of difference in planet occurrence rates between [main sequence] and giants before because we did not have enough planets to statistically see this difference before. It’s a very promising approach.”

Planets: Part of a Balanced Stellar Breakfast

Exoplanet science is one of astronomy’s biggest successes in the modern era: Since the first exoplanet discovery 30 years ago, astronomers have confirmed more than 6,000 planets and identified many more candidates for follow-up observations. At the same time, the work can be challenging when it comes to planets orbiting post–main sequence stars.

One tricky aspect of this work is related to the age of the stars, which formed billions of years before our Sun. Older stars have a lower abundance of chemical elements heavier than helium, a measure astronomers call “metallicity.” Observations have found a correlation between high metallicity and exoplanet abundance.

“A small difference in metallicity…could potentially double the occurrence rate.”

“A small difference in metallicity…could potentially double the occurrence rate,” Reffert said, stressing that the general conclusions from the article would hold but the details would need to be refined with better metallicity data.

Future observations to measure metallicity using spectra, along with star and planet mass, would improve the model. In addition, the European Space Agency’s Plato Mission, slated to launch in December 2026, will add more sensitive data to the TESS observations.

Earth’s fiery fate is a long way in the future, but researchers have made a big step toward understanding how dying stars might eat their planets. With more TESS and Plato data, we might even glimpse the minute orbital changes that indicate a planet spiraling to its doom—a grim end for that world but a wonderful discovery for our understanding of the coevolution of planets and their host stars.

—Matthew R. Francis (@BowlerHatScience.org), Science Writer

Citation: Francis, M. R. (2025), Planet-eating stars hint at Earth’s ultimate fate, Eos, 106, https://doi.org/10.1029/2025EO250448. Published on 2 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: GeoHealth

Heatwaves can disrupt many parts of daily life, including access to essential healthcare services. Dey et al. [2025] evaluate how heatwaves are related to where women in India give birth.

The authors analyze data from over 200,000 births during 2019-2021 and find that during periods of heatwaves, women were more likely to deliver at home instead of in a health facility. This association was stronger for warmer regions, regions without government programs supporting facility-based births, and non-Hindu populations. The study indicates that extreme heat may create barriers to healthcare services (e.g., difficulty traveling or strained health services), which makes it challenging to reach a hospital in time for delivery. This brings a major concern because giving birth at home without a skilled medical attendant may lead to higher health risks for both the mother and the newborn.

As the frequency and intensity of heatwaves increases under climate change, these findings emphasize the urgent need for early warning systems and stronger healthcare support to protect vulnerable mothers and newborns.

Citation: Dey, A. K., Dimitrova, A., Raj, A., & Benmarhnia, T. (2025). Heatwaves and home births: Understanding the impact of extreme heat on place of delivery in India. GeoHealth, 9, e2025GH001540. https://doi.org/10.1029/2025GH001540

—Lingzhi Chu, Associate Editor, GeoHealth

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

When hurricanes or strong storms sweep up the United States' East Coast and meet the shores of the country's largest estuary, Chesapeake Bay, the familiar pattern of storm activity gets a little more complicated. A new study, published in the Journal of Geophysical Research: Oceans, shows that water levels inside the bay can spike far more dramatically than along the open ocean, raising flood risks for coastal and inland communities.

Major storms are spreading industrial contaminants across entire neighborhoods, raising concerns about future well-being, especially in communities of color, according to new research from Rice University and the University of Alberta.

A new algorithmic framework that can predict flooding could help save lives and reduce the devastation as climate change drives more intense and unpredictable rainfall.

More than 900 people are dead, thousands more missing and millions affected by a band of cyclones and extreme monsoonal weather across southern Asia. Torrential rain has triggered the worst flooding in decades, accompanied by landslides. Indonesia, Sri Lanka, Thailand, Vietnam and Malaysia have been hit hardest. The death toll is likely to rise significantly.

A new study published in Scientific Reports reports the discovery of a remarkably extensive hydrothermal vent field on the shelf of Milos Island, Greece. The vents were identified during the METEOR expedition M192, where the research team used a combination of different methods, including underwater technologies such as autonomous and remotely operated vehicles, to survey the seafloor.

In a step toward better understanding how the ocean sequesters carbon, new findings from UC Santa Barbara researchers and collaborators challenge the current view of how carbon dioxide is "fixed" in the sunless ocean depths. UCSB microbial oceanographer Alyson Santoro and colleagues, publishing in the journal Nature Geoscience, present results that help to reconcile discrepancies in accounting for nitrogen supply and dissolved inorganic carbon (DIC) fixation at depth.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

Using data from the GRACE and GRACE-FO satellite missions, Rateb et al. [2025] monitored global changes in terrestrial water storage to study how hydrological extremes—floods and droughts—have developed over the past two decades. Their analysis indicates that these extremes are mainly driven by climate variability in tropical oceans, with both interannual and multi-year patterns playing a significant role.

However, the approximately 22-year satellite record is still too short to fully identify long-term drivers, which limits the ability to determine whether global extremes are increasing or decreasing. To fill data gaps in certain months, the authors use non-parametric probabilistic methods to reconstruct storage anomalies. The reconstructed data closely matched independent datasets, confirming the reliability of their approach. Overall, the study highlights the need to extend satellite observations to capture multi-decadal climate variability and better distinguish natural fluctuations from human-induced changes.

Citation: Rateb, A., Scanlon, B. R., Pokhrel, Y., & Sun, A. (2025). Dynamics and couplings of terrestrial water storage extremes from GRACE and GRACE-FO missions during 2002–2024. AGU Advances, 6, e2025AV001684. https://doi.org/10.1029/2025AV001684

—Tissa Illangasekare, Editor, AGU Advances

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

A new Tulane University study published in Science Advances sheds light on how floods influence the way rivers move, offering fresh insight into how changing flood patterns may reshape waterways and the communities that depend on them.

Coral reefs have long been celebrated as biodiversity hotspots—but new research shows they have also played a much deeper role: conducting the rhythm of Earth's carbon and climate cycles for more than 250 million years.

Publication date: Available online 26 November 2025

Source: Advances in Space Research

Author(s): Jorge Samanes, Alejandra Hinostroza Caldas, R.Y.C. Cueva, Emilia Correia

Publication date: Available online 25 November 2025

Source: Advances in Space Research

Author(s): Anshul Singh, Qadeer Ahmed, Aastha Rawat, Ankit Gupta, Arti Bhardwaj, Ashish Ranjan, Puja Goel, Arun Kumar Upadhayaya

Publication date: Available online 25 November 2025

Source: Advances in Space Research

Author(s): Rituraj Neog, Behnam Ghasemzadeh

Publication date: Available online 25 November 2025

Source: Advances in Space Research

Author(s): XuMing Yang, YaJing kang, ChunKang Zhang