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Horizontal vortex tubes may have a significant impact on tornado development

Phys.org: Earth science - Wed, 09/24/2025 - 19:11

Tornadoes on the outer edges of a typhoon's spiral rain bands are a severe convective weather phenomenon that occurs on the periphery of tropical cyclone systems. Compared to the core region near the typhoon's center, the atmospheric instability and vertical wind shear conditions in these outer areas often combine in more subtle and easily overlooked ways, making their occurrence and development more sudden and localized. This poses greater challenges for forecasting and early warning.

Climate Change Could Slash Global GDP 24% By 2100

EOS - Wed, 09/24/2025 - 19:02

body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news that impacts science and scientists today.

Unchecked greenhouse gas emissions could cause the world’s income to fall by nearly a quarter within the century, projects a new study published in PLOS Climate.

“Climate change reduces income in all countries, hot and cold, rich and poor alike.”

“Climate change reduces income in all countries, hot and cold, rich and poor alike,” the study’s authors wrote in a press release.

Gross domestic product, or GDP, is the total value of goods and services produced in a given year. A country’s per-capita GDP is a measure of the average income of a person living there.

In the new study, researchers turned to information about the previously studied link between rising temperatures and GDP, along with possible scenarios of future warming, called Shared Socioeconomic Pathways. They used this data to simulate more precisely how rising temperatures might impact global GDP over time.

Their projections show warming could cause widespread economic losses as higher temperatures and climate variability impact the activities of industries including agriculture and manufacturing. But reducing greenhouse gas emissions could soften the effect, the authors write.

In a moderate emissions scenario (SSP2-4.5), global GDP decreased by about 2.5% by 2100. In a high-emissions scenario with minimal adaptation (SSP3-7.0), the projections showed global per-capita GDP dropping by up to 11%. And in a more extreme emissions scenario (SSP5-8.5) without any climate mitigation or adaptation, the researchers projected per-capita income losses of up to 24%.

Under this extreme scenario, the United States would lose nearly a third of its per-capita GDP by 2100.

The estimated changes in global income compared to the 1960-2014 warming trend, as well as a world without climate change, varied depending on the warming scenario that the researchers used. Credit: Mohaddes and Raissi, 2025, https://doi.org/10.1371/journal.pclm. 0000621

The results are in line with previous research from 2024, which indicated a likely decrease in global income by 11% to 29%, depending on future emissions scenarios. However, the new study finds that if the world’s governments abide by Paris Agreement goals—that is, limiting temperature increases to 0.01°C (0.02°F) per year—global GDP could slightly increase by 0.25% by 2100.

In both the new study and previous research, low-income and hotter countries fared the worst: In the new study’s projections, countries located in hot climates and classified as low-income faced income losses between 30% and 60% of the global average.

The publication comes on the heels of a speech at the United Nations General Assembly in which President Trump called climate change the “greatest con job ever perpetrated on the world.” That denialism won’t preserve global income, according to the authors: “Urgent action is needed to address climate change and protect economies from further income losses,” they wrote.

—Grace van Deelen (@gvd.bsky.social), Staff Writer

These updates are made possible through information from the scientific community. Do you have a story about science or scientists? Send us a tip at eos@agu.org. Text © 2025. AGU. 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.

Mantle 'chemical patchiness': Study provides first direct evidence of its spatial scale

Phys.org: Earth science - Wed, 09/24/2025 - 16:25

A joint research group has identified that the spatial scale of "heterogeneity" in the upper mantle, caused by a large-scale flow called a mantle plume rising from deep Earth, is less than 10 kilometers.

Scientists warn California should prepare for destructive 'supershear' earthquakes

Phys.org: Earth science - Wed, 09/24/2025 - 15:50

Most Californians are familiar with earthquakes. But researchers say the state faces an overlooked threat: "supershear" earthquakes that move so fast they outrun their own seismic waves.

Magma displacement triggered tens of thousands of earthquakes, Santorini swarm study finds

Phys.org: Earth science - Wed, 09/24/2025 - 15:00

Tens of thousands of earthquakes shook the Greek island of Santorini and the surrounding area at the beginning of the year. Now, researchers have published a comprehensive geological analysis of the seismic crisis in the journal Nature.

中国推进现代农业，小农户面临风险

EOS - Wed, 09/24/2025 - 14:47

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

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

在中国，通过大规模耕作实现农业现代化的努力，将许多参与了全国大部分粮食生产的小农户推到了边缘。一个颇具前景的解决方案是“循环农业”，它通过鼓励大规模和小规模农业经营之间的合作，重点关注可持续性、生产力和农村经济发展。

在Community Science期刊关于可持续农业跨学科合作的特刊中，Li 和 Nielsen[2025]研究了中国西南部一个将柚子种植与养猪相结合的循环农业项目。作者对小农户、政府官员、金融机构员工以及其他各类利益相关者进行了35次访谈，了解了该模式面临的各种利益和风险。

他们的研究结果表明，地方政府在搭建合作平台方面发挥着关键作用，而农业合作社则是商务管理的核心。该研究还揭示了政府参与往往出于政治动机，小农户在决策过程中可能失去自主权和公平代表权等挑战。作者建议，要使循环农业真正惠及每个人，小农户需要有话语权和权力来决定自己的未来，而不能让自己的利益受到侵犯。

Citation: Li, H., & Nielsen, J. Ø. (2025). Smallholders, capital, and circular agriculture—The case of combined pomelo and pig farming in southwest China. Community Science, 4, e2025CSJ000127. https://doi.org/10.1029/2025CSJ000127

—Claire Beveridge, Editor, Community Science

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.

More than half of world's coastal settlements retreating from rising seas, study shows

Phys.org: Earth science - Wed, 09/24/2025 - 14:33

Human settlements around the world are moving inland and relocating away from coastlines as sea levels rise and coastal hazards grow more severe, but a new international study shows the poorest regions are being forced to stay put or even move closer to danger.

The Ganges River is drying at an unprecedented rate, new study finds

Phys.org: Earth science - Wed, 09/24/2025 - 13:34

The Ganges River is in crisis. This lifeline for around 600 million people in India and neighboring countries is experiencing its worst drying period in 1,300 years. Using a combination of historical data, paleoclimate records and hydrological models, researchers from IIT Gandhinagar and the University of Arizona discovered that human activity is the main cause. They also found that the current drying is more severe than any recorded drought in the river's history.

Major Droughts Coincided with Classic Maya Collapse

EOS - Wed, 09/24/2025 - 10:55

A stalagmite in a Yucatán cave has provided new insight into the role drought may have played in Maya sociopolitical shifts more than 1,000 years ago. A recent analysis of a rainfall proxy in the Maya lowlands revealed that several episodes of severe, prolonged drought occurred during the Maya Terminal Classic Period (roughly 800–1000 CE), a time when large urban centers experienced major sociopolitical shifts.

The researchers suggest that just as climate change acts as a threat multiplier today, drought may have amplified existing troubles in Maya political centers like Chichén Itzá and Uxmal and added climate stress to societies already under pressure.

“These climate events would have affected each individual site in a very specific way depending on the resilience of that site at that time,” said lead researcher Daniel James, who studies paleoenvironmental reconstruction at University College London. “Hopefully the precision of this record allows that [analysis] to be done at individual sites…then we can really start to build up a picture of what I am certain will be a wide variety of societal responses to climate change across this time and across the region.”

Extended Droughts During Wet Seasons

During the Maya Terminal Classic Period, several Maya city-states in the southern lowlands (in modern-day Mexico, Belize, and Guatemala) experienced sociopolitical upheaval, site abandonment, and depopulation. Political and cultural centers shifted northward. Although the societal changes are clear in the archaeological record, there is still widespread debate about the potential drivers of these shifts as well as why some city-states survived while others did not.

This map of the Maya lowlands in Yucatán marks sites of prior paleoclimate studies with white squares, with this study’s site, Grutas Tzabnah, marked with an X. White circles denote Northern Maya Lowland sites, and stars denote sites of interest to this study. The land is shaded on the basis of its elevation in meters above sea level (m asl). Blue contours outline modeled mean annual total rainfalls from 1979 to 2022 in millimeters per year. Credit: James et al., 2025, https://doi.org/10.1126/sciadv.adw7661, CC BY 4.0

Drought comes up often in these debates as a potential destabilizer: Insufficient or unpredictable rainfall can lead to food instabilities, trade disruptions, disease, and even military conflicts. But previous paleoclimate studies failed to precisely pin down the timings and durations of droughts in the Maya lowlands during the Terminal Classic Period, James said.

James and his colleagues trekked to a cave called Grutas Tzabnah, in the state of Yucatán, Mexico, located near several large Classic Maya sites, including Chichén Itzá and Uxmal. This cave has been sought out before for paleoclimate studies of the region because of its accessibility and well-preserved cave formations. What’s more, Grutas Tzabnah is also a relatively shallow cave, which means that water does not take long to drip into the cave from ground level.

The researchers chose a stalagmite that has been growing for thousands of years and shows distinct annual growth layers. This particular stalagmite grew fast in the layers that dated back to the Maya Terminal Classic Period, James said, so the team was able to collect 10–20 data points within each annual layer to determine subannual, seasonal rainfall.

Researchers Daniel James (left), Ola Kwiecien (center), and David Hodell (right) install a drip water autosampler in Grutas Tzabnah to analyze seasonal changes in drip chemistry. Credit: Sebastian Breitenbach, 2022

“You can see wet seasons and dry seasons in our record, whereas previous records from the same cave are looking at annual average rainfall,” James said. “Wet season rainfall is what determines the success or failure of agriculture, as opposed to annual average.”

They measured the ages of the layers using uranium-thorium radiometric dating and rainfall quantity using a stable oxygen isotope ratio, δ18O, within calcite. Stalagmite samples that recorded a lower δ18O indicate more rainfall, while higher δ18O indicates less rainfall. The team calibrated their paleoclimate calculations with modern rainwater and cave drip measurements over a few years to ensure that they could convert the stalagmite’s δ18O measurements to rainfall.

From 871 to 1021, the stalagmite recorded eight extreme droughts during wet seasons, each lasting at least 3 years. A 4-year drought that started in 894 was interrupted by a single wet year and was followed by another 5 years of wet-season drought. A few decades later, the region had experienced 13 consecutive years of wet-season drought (929–942), longer than any multiyear drought in local historical records. This research was published in Science Advances in August.

“The chronology makes this one of the most detailed paleoclimate records available for understanding human-climate interactions during the Maya collapse period.”

“This new study represents a significant advancement in our understanding of Terminal Classic drought patterns, primarily due to its exceptional temporal resolution and robust age control with uncertainties of just a few years,” said Sophie Warken, who studies speleothems and climate variability at Universität Heidelberg in Germany and was not involved with this research.

“This high-resolution approach enables the authors to examine the timing and duration of individual drought episodes very precisely, which previous studies could only identify as broad periods of drying,” Warken added. “The chronology makes this one of the most detailed paleoclimate records available for understanding human-climate interactions during the Maya collapse period.”

One Piece of the Puzzle

While this rainfall record is a big step forward, Warken said that she would like to see it verified using additional proxies like trace elements, as well as a longer modern calibration period. She would also like to see this record extended to before and after the Terminal Classic Period to gauge whether those droughts were truly exceptional for the region.

“Such expanded paleoclimate networks could also provide crucial baselines for assessing recent and future climate changes in this vulnerable region,” she added.

Despite the fact that the extended droughts coincide with major societal shifts, James cautioned that this does not mean that drought caused these changes or were even the most important factor.

“I would love for this data to be used to pick apart individual stories from individual sites of resilience and survival, as well as the stories of disintegration of systems and abandonment and loss of population.”

“Other hardships like famine, disease, and internal violence could have been caused by drought or indeed could have been ongoing beforehand and made the society more susceptible to and less prepared for climate hardship,” James said.

Importantly, archaeological evidence suggests that two Maya cities near this cave, Chichén Itzá and the regional capital of Uxmal, did not decline at the same rate. (Uxmal declined much more rapidly.) Understanding the pressures that the two cities experienced, including drought, will be key to creating a holistic picture of how the cities functioned during the Terminal Classic Period.

“While climate stress likely played an important role in the Terminal Classic transformations,” Warken said, “the Maya’s response to drought was probably mediated by existing social, political, and economic vulnerabilities that varied between different centers and regions.”

“It could be how well were they ruled, how rigid or flexible was their political system, how good was their water management at the time,” James said.

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

Citation: Cartier, K. M. S. (2025), Major droughts coincided with Classic Maya collapse, Eos, 106, https://doi.org/10.1029/2025EO250361. Published on 24 September 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.

Free-Roaming Bison Graze Life into Grasslands

EOS - Wed, 09/24/2025 - 10:47

By the end of the 19th century, most of the estimated 30 million to 60 million bison roaming North America’s Great Plains had been eradicated, forever changing the landscapes that they lumbered across. Today, only about 400,000 bison remain in North America, and 95% of those animals are raised and managed for meat production. The remaining bison live in carefully controlled conservation settings, such as Yellowstone National Park.

Though existing research suggests that grazing bison can diversify habitats and drive nutrient cycling and productivity, studying how they shape larger, ecosystem-scale landscapes has been difficult. A new study conducted in Yellowstone does just that, showing how bison grazing boosts nitrogen cycling and improves plant health to create resilient grasslands.

Yellowstone offers a unique national laboratory for the study because the 5,000 bison who call the park home range freely along a 50-mile (80-kilometer) migration route. Their migration is a reminder of a time when millions of these massive herbivores roamed the continent.

Grazing Helps the Grass Grow

Researchers measured the plant productivity of 16 Yellowstone sites between 2015 and 2022. These sites spanned across lawn-like valley bottoms, which were grazed throughout grass-growing seasons; dry hillsides, which were grazed in spring, fall, and winter (depending on snowpack); and high-elevation wet areas, which were grazed from early summer until frosts arrived.

“Bison are true grazers. They put their heads down and just do their thing.”

Though other species subsist on these grasses, cameras and GPS data from tracking collars showed bison were the primary grazing animals in these locations. “Bison are true grazers. They put their heads down and just do their thing, whereas elk and mule deer and pronghorn are a little more selective in what they eat,” said study author Bill Hamilton, an ecologist at Washington and Lee University.

To compare areas of vegetation that were and were not grazed by bison, researchers constructed a series of movable “exclosures” that kept bison out of 9-square-meter areas. Some of the exclosures remained fixed in place from April, when snowpack melts and new plants emerge, to October, the time when grasses stop growing. Moveable exclosures, shifted every 30 days, followed the bison along their migration path.

By comparing fenced and unfenced areas, researchers were able to estimate how much biomass had been eaten. The missing biomass was added back into the productivity total to give a fuller picture of plant production. “It would be like if each time you mow your lawn and put it into a bag and then you weighed that pile at the end of the summer, you would know how much your grass you actually grew,” said Hamilton.

Having thousands of large animals grazing at once may seem like it would inhibit plant growth, but the study showed the opposite effects. As bison graze, they speed up the nitrogen cycle in the plants and soil around them. Urine is one concentrated source of nitrogen, and as it enters the soil, enzymes and microbes break it down into ammonia, which is then converted to ammonium. Some plants absorb the ammonium directly, and microbes further convert some of the ammonium into nitrate that is absorbed by other plants.

Populations of ammonium-oxidizing bacteria were concentrated more highly in heavily grazed areas, leading to more available nitrogen for plant growth. Researchers determined nitrogen levels by burying reverse osmosis membranes in the ground and measuring the amount of ammonium and nitrate collected on the membrane after 30 days.

The large amounts of bison urine and feces entering the soil weren’t the only cause of increased nitrogen, Hamilton explained. “We found differences in the amount of nitrogen in the leaf tissue above ground. But where’s it coming from? It’s coming from the nitrogen cycle that’s being stimulated by the grazing.”

Mutually Beneficial

When a bison chomps off the top of a patch of grass, the plants quickly release carbon into the soil through their roots to regrow their lost tissue. The carbon stimulates the microbes belowground to accelerate decomposition and nutrient cycling. “In 7 days, there’s more nitrogen in the leaf tissue of that [grazed] plant than a comparable ungrazed plant,” said Hamilton. “The key is that plants are not passive in this process.”

“Animals, through their natural behavior of congregating and eating and hanging out, are changing the way plant communities grow and respond.”

Increased nitrogen in the grasses means more nutritious food for Yellowstone’s migrating bison herds and resident ruminants: The rise in nitrogen translated to a 156% crude protein increase in lawn-like grasslands, a 155% increase in high-elevation habitats, and a 119% increase in dry areas.

“What this study tells me is that what’s happening in Yellowstone is very special,” said Tyler Kartzinel, an ecologist at Brown University who was not part of the study. “Animals, through their natural behavior of congregating and eating and hanging out, are changing the way plant communities grow and respond. And that has cascading effects on nutrient cycling and the functioning of the entire ecosystem.”

Yellowstone and Beyond

Yellowstone’s free-roaming bison herds provide a glimpse at the past, but they also might offer insight into how to preserve and improve grasslands in the future, the study authors suggest. When large groups of herbivores move freely across landscapes—like wildebeest in the Serengeti and caribou in Alaska—they can influence the broader ecosystem in a positive way.

Restoring bison in large-scale settings allows them to fulfill not only significant ecological roles but cultural roles as well. “That’s important for Indigenous tribes that have spiritual and cultural connections to these animals,” said Hamilton.

Besides Yellowstone, few places exist in North America to study how large grazing animals affect the land that sustains them. The nonprofit American Prairie aims eventually to connect 3.2 million acres (about 1.3 million hectares) of grasslands and host thousands of free-roaming bison in Montana—offering another venue where bison could migrate and interact with plants and soil on a large scale. “This study says it could work,” said Hamilton.

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

Citation: Owen, R. (2025), Free-roaming bison graze life into grasslands, Eos, 106, https://doi.org/10.1029/2025EO250355. Published on 24 September 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.

Supercritical subsurface fluids open a window into the world

Phys.org: Earth science - Wed, 09/24/2025 - 09:00

Researchers have built on past studies and introduced new methods to explore the nature and role of subsurface fluids, including water, in the instances and behaviors of earthquakes and volcanoes. Their study suggests that water, even heavy rainfall, can play a role in or even trigger seismic events. This could potentially lead to better early warning systems.