Feed aggregator

SummaryAccurate quantification of natural gas hydrate is essential for resource potential and climate impact assessment. Archie’s empirical equations are commonly used to quantify hydrates from electrical resistivity measurements. One dominant Archie equation parameters, i.e. saturation parameter (n), is generally assumed to be constant for different hydrate saturation range for a given reservoir. However, n actually varies with hydrate saturation and morphology, and the exact relationship between n and hydrate saturation or morphology still remains poorly understood, leading to great uncertainties in resistivity-derived saturations. Here we investigate the effect of hydrate saturation and dominant hydrate morphologies on n using well logs from four sites in both fine and coarse-grained sediments: two sites with fluid-displacing hydrate (site W11 from the third Guangzhou Marine Geologic Survey; and Mallik 5L-38 well in the Mackenzie Delta) and two sites with fracture-filling hydrate (site 10 from Indian National Gas Hydrate Program Expedition 01; and site W08 from the second Guangzhou Marine Geologic Survey). We calculated n value using Archie’s law with hydrate saturation determined from velocity. Our results demonstrate a clear negative relationship between hydrate content and n value. Moreover, n estimates from two fracture-filling sites show greater variability compared to fluid-displacing sites. At a fracture-filling hydrate site, site 10, various trends between n and hydrate saturation are possibly caused by the distint gas compositions of hydrate. Our results demonstrate that significant effects of hydrate morphology and saturation on n that are site specific, and can be used to enhance the accuracy of gas hydrate quantification.

SummaryFull-waveform inversion (FWI) is a method that utilizes seismic data to invert the physical parameters of subsurface media by minimizing the difference between simulated and observed waveforms. Due to its ill-posed nature, FWI is susceptible to getting trapped in local minima. Consequently, various research efforts have attempted to combine neural networks with FWI to stabilize the inversion process. This study presents a bidirectional physics-constrained full waveform inversion (BP-FWI) framework that leverages transfer learning by pre-training on simple initial models and utilizing the results. Additionally, it employs FWI gradients to co-optimize both the neural network and the adaptive residual learning module under bidirectional physics constraints. By eliminating the reliance on a large amount of manually constructed synthetic datasets, the proposed training strategy addresses the challenge of data dependency. Furthermore, through the joint optimization strategy guided by bidirectional constraints, the neural network is able to focus on integrating physically-informed prior knowledge into global stratigraphic representations, while the adaptive residual learning module specializes in learning residual mappings from the network’s output, thereby capturing subtle inter-layer velocity variations in local geological structures. Evaluating the method on two benchmark models under various conditions, including absent low-frequency data, noise interference, non-uniform receiver configurations, and differing initial models, along with corresponding ablation experiments, consistently demonstrates the superiority of the proposed approach.

Source: Earth’s Future

Water levels are creeping upward on shorelines across the world, and decisionmaking systems are not keeping up. One barrier to including sea level rise projections in adaptation plans is limited information on the full range of possible outcomes.

Substantial scientific uncertainty exists around how quickly ice sheets could collapse. This uncertainty means high-end sea level rise projections have been particularly tough for coastal planners to incorporate into their risk assessments for critical infrastructure such as nuclear power plants. In the United Kingdom, current official guidance states that planners should consider a worst-case scenario of 1.9 meters of sea level rise by 2100, but recent scientific evidence suggests that worse scenarios are plausible. Given the broad range and large uncertainty surrounding high-end projections, new tools for decisionmakers are sorely needed.

Weeks et al. present a new decisionmaking framework that includes a “decision-game” approach. This decision-game approach involves a time-step based progression through a plausible sea level rise scenario, allowing participants to prime long-term thinking skills, analyze impacts of previous decisions, and test their strategies for adaptation. The new framework, coproduced by the United Kingdom’s Met Office and Environment Agency, also incorporates scientific advances that have taken place since the last major update to high-end sea level rise projections in 2009.

To test their framework, the researchers held a decision-gaming workshop that was attended by consultants, coastal risk management experts, and climate change advisers. The researchers presented a hypothetical U.K. coastal city to the participants and gradually revealed the local sea level change over the 21st century and beyond for a high-end scenario. Participants held nuanced discussions and gained a deep understanding of the ramifications that their adaptation planning decisions would have over time, the researchers report. With widespread deployment, the framework could help coastal communities build resilience against rising waters. The researchers also note that the approach could be adapted to help make decisions about managing other climate hazards in various regions. (Earth’s Future, https://doi.org/10.1029/2025EF006086, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), A new way for coastal planners to explore the costs of rising seas, Eos, 106, https://doi.org/10.1029/2025EO250375. Published on 18 November 2025. 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.

About 1.5 million years ago, the mid-depth waters of the tropical Pacific Ocean suddenly grew cooler. The change came rapidly, and it spread across thousands of kilometers.

Before then, Earth’s climate had been relatively stable. Cycles of ice ages and interglacial periods had already begun, but they were shorter, and the tropical Pacific remained warm. Its surface temperature barely changed even as polar ice advanced and retreated.

So how did the waters suddenly become cold?

“We’re usually interested in the mid-depth waters—not the surface, not the deep ocean—because that’s where the music is.”

A new study published in Communications Earth and Environment suggests that the cold water came from the Southern Ocean and traveled northward through ocean tunnels into the tropics. An ocean tunnel, the research explains, describes a “channel for water masses that connects different oceanic and consequently, atmospheric regions.”

“We’re usually interested in the mid-depth waters—not the surface, not the deep ocean—because that’s where the music is,” said Jacek Raddatz, a climate scientist at GEOMAR Helmholtz Centre for Ocean Research Kiel, in Germany, and first author of the study.

“The Pacific is the largest ocean and important for global circulation and climate,” he continued. “That’s why we focused our study on the tropical Pacific.”

Tunnels of Colder, Fresher Water

The researchers analyzed tests of planktonic foraminifera (forams) recovered from a sediment core drilled from the Manihiki Plateau, a submerged ridge in the tropical South Pacific. The plateau is located at the eastern edge of the Western Pacific Warm Pool, the region with the highest ocean temperatures in the world.

The team measured magnesium-to-calcium ratios and oxygen isotope values in tests of two species of forams. One species lived near the surface, and the other lived about 400 meters down. With those values, the scientists reconstructed past temperatures and salinity spanning a period from about 2.5 million to 1 million years ago.

“At the Manihiki Plateau, we see that around 1.5 million years ago, there’s a drop in both temperature and salinity,” said Raddatz.

This timing matched a major growth of Antarctic ice.

The new research indicates cold Antarctic water traveled northward through the Pacific’s mid-depths as a pulse, a process known as ocean tunneling.

“Cold water forms off places like Chile, Peru, and California and slowly sinks. It moves toward the equator beneath the surface,” explained Matt Luongo, a climate scientist and postdoctoral researcher at the University of Washington, in Seattle. He was not involved in the study. “If that water becomes cooler or fresher, then maybe…10 to 20 years later, the equator ends up bringing up cooler water too. That’s basically how ocean tunneling connects distant parts of the ocean.”

Raddatz and his fellow researchers also examined how the cooling was related to Earth’s orbital cycles: eccentricity, or the shape of Earth’s orbit; obliquity, or the angle at which Earth’s axis is tilted with respect to its orbital plane; and precession, or the direction Earth’s axis is pointed.

They found a consistent pattern. “We see the same increase in obliquity-related signals in Antarctic ice volume, in midlatitude temperature reconstructions, and in our salinity record,” Raddatz said. “That led us to conclude that they’re all connected through the same mechanism.”

Raddatz and his colleagues think the cooling may have been an early step toward the period when Earth’s ice ages grew longer and more intense. “We think this might be a first step that led, maybe, to the Mid-Pleistocene Transition.”

Interesting, but Not Definitive

Luongo agreed the study shows that South Pacific waters did chill out and freshen up about 1.5 million years ago and that the source of these changes came from the Southern Hemisphere. The research is “interesting, because it helps explain why the thermocline in the equatorial Pacific is so cold and fresh,” he said.

But he also cautioned against directly linking the changes to Antarctic ice growth. “It’s suggestive of the ice sheet, the wiggles match, but it also could be something else,” said Luongo. “There are a lot of things that can cause freshening of the waters.”

Raddatz and his colleagues plan to extend their work to other ocean basins. They want to add nutrient and carbon measurements to build a fuller picture of how mid-depth waters evolve. “If we understand these variations,” he said, “we can also explain the growth and decline of biodiversity hot spots in the deep sea.”

—Larissa G. Capella (@CapellaLarissa), Science Writer

Citation: Capella, L. G. (2025), Ocean tunneling may have set off an ancient Pacific cooldown, Eos, 106, https://doi.org/10.1029/2025EO250428. Published on 18 November 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.

Source: Journal of Geophysical Research: Biogeosciences

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

氮是全球环境的重要组成部分，影响着农业、气候、人类健康和生态系统。氮循环的作用已经得到了更广泛的认识，然而用于预测全球环境变化的地球系统模型（ESM）仍然没有将其完全纳入考量。

Kou-Giesbrecht主张在ESM中交互式地纳入完整的氮循环，以解释氮在陆地、海洋和大气之间复杂且相互关联的流动方式。氮直到最近才被纳入一些ESM的陆地模型中，并且仅仅作为初级生产力的限制因素。

氮的作用远不止于植物生长，它还是一种强效温室气体，也是臭氧形成和气溶胶成分的重要驱动因素。野火会释放氮氧化物和氨，导致颗粒物浓度升高；海洋微生物既吸收氮也释放氮。氮向海洋的输出会影响海洋初级生产力，也影响海洋氮的排放，而海水中过量的氮会导致富营养化，即营养物质过剩，从而引发有害藻类大量繁殖。

尽管氮循环在全球范围内都非常重要，但ESM中的许多氮循环组成部分即使被包括在内，也不是完全交互的，有些甚至根本没有被纳入模型；相反，它们只是作为静态输入提供给模型。作者认为，在陆地、海洋和大气之间动态模拟氮循环，将大大缩小我们对地球气候和环境近期演变的认知差距。

为了实现这一目标，我们需要更多的观测数据来更好地建立陆地氮循环的基准模型，并开展实验操作，为氮相关过程提供经验约束。作者指出，这些进展有助于我们理解并实现《科伦坡可持续氮管理宣言》的目标，即到2030年将氮废弃物减少一半，这样每年可以节省1000亿美元，并有助于减缓气候变化，改善生物多样性、粮食安全和公共卫生。(Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2025JG009209, 2025)

—科学撰稿人Nathaniel Scharping (@nathanielscharp)

This translation was made by Wiley. 本文翻译由Wiley提供。

Read this article on WeChat. 在微信上阅读本文。

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.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Solid Earth

Giant dyke swarms are networks of long, sheet-like cracks in Earth’s crust that carry molten rock (magma) sideways for hundreds of kilometers. In a new study, Foschi and Cartwright [2025] use shallow, laterally injected sills—thin, horizontal sheets of solidified magma—as natural pressure gauges to reconstruct magma pressure along a 660 kilometers dyke from the Mull volcanic center.

The authors run large Monte Carlo simulations (many randomized model runs) to account for uncertainty and find that magma pressure remained high enough that eruption at the surface should have been possible in many places. Despite that, the dykes did not erupt, and the paper shows the classic ideas of neutral buoyancy (where magma stops rising because it becomes the same density as the surrounding rock) or simple mechanical blockage do not explain this. Instead, field evidence and the pressure reconstructions point to near‑surface cooling by groundwater: when hot magma meets cold water or wet sediment it cools, becomes more viscous (thicker), and stalls before reaching the surface.

This finding matters because it changes how we think about long‑range magma transport and eruption risk: strong subsurface cooling can prevent eruptions even when subsurface pressures are high. The sill‑piezometer approach also offers a practical method for constraining magma pressure in other volcanic systems, improving models of where and how magma moves underground.

Citation: Foschi, M., & Cartwright, J. A. (2025). Constraints on magma pressure distribution during long range lateral propagation of giant radial dyke swarms. Journal of Geophysical Research: Solid Earth, 130, e2025JB031995. https://doi.org/10.1029/2025JB031995

—Nikolai Bagdassarov, Associate Editor, JGR: Solid Earth

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.

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.

The world has made significant progress on methane mitigation since 2020, though meeting the goals of a major international pledge will require additional action, according to a United Nations Environment Programme (UNEP) report. 

The report was publicized today at the UN Framework Convention on Climate Change Conference of the Parties (COP30) in Belém, Brazil. It is the first comprehensive stocktake of global methane emissions since the 2030 Global Methane Pledge, an international agreement that aims to reduce global methane emissions by 30% compared to 2020 levels by 2030, was launched in 2021.

“The global methane pledge is still achievable.”

“The global methane pledge is still achievable,” said Ruth Zugman do Coutto, the deputy director for UNEP’s Climate Change Division, in a press conference. “We have the tools, technologies and data, and 80% of the reduction potential can be achieved through low cost measures available today, but we must accelerate action now.”

Methane is a powerful greenhouse gas able to warm the atmosphere about 30 times as much as the equivalent amount of carbon dioxide. Human-caused methane emissions come mostly from agriculture, livestock, natural gas, and landfills. 

Though global methane emissions are still rising, new waste regulations in Europe and North America, slower growth of natural gas markets, and additional national pledges to reduce methane have lowered projected global methane emissions. Countries’ new 2025 commitments are projected to cause an 8% reduction in human-caused methane emissions by 2030 compared to 2020-level commitments. If these commitments are realized, they would be the largest decline in methane emissions in history.

“We have seen an unprecedented increase in the availability and quality of data and knowledge, and the ambition for methane abatement. This is proof of what collective action can achieve,” wrote Cristina Lobillo Borrero, the director for international relations and energy security at the European Commission and Tibor Stelbaczy, the European Union principal adviser on energy diplomacy, in the report.

“Knowledge is still missing in terms of the broad coverage of all the millions of individual emitters in all sectors.”

However, meeting the 2030 Global Methane Pledge will require additional action and adoption of broader methane-reducing and methane-tracking technologies, the report states. 

For example, though satellites track emissions from so-called methane “super-emitters” in detail, such entities still collectively represent a minority of total global methane emissions, wrote Stefan Schwietzke, senior scientist at data integration lead for UNEP’s International Methane Emissions Observatory (IMEO), in an email. “Knowledge is still missing in terms of the broad coverage of all the millions of individual emitters in all sectors,” he wrote. 

All methane sources require more monitoring, but methane from rice farming and ruminants (a class of livestock that includes cattle, sheep, and goats), are particularly under-studied, Schweitzke wrote. Fragmentation of existing data and the use of different measurement technologies in different regions also hamper a straightforward understanding of the origins of methane emissions: “It is critically important to start integrating the existing data to build on current knowledge,” he wrote.

 
Related

•  Read the Report: Global Methane Status Report 2025
•  Global Methane Pledge
•  Ministers Urge Decisive Methane Action as Global Report Shows Progress, Warns of Gaps
•  Get Involved: AGU Science Policy Action Center
 

IMEO works to help national governments study methane emissions and build their capacity to monitor methane.

Meeting the Global Methane Pledge would avoid 0.2°C (0.36°F) of warming and more than 180,000 premature deaths by 2050 as well as $330 billion in annual avoided damages by 2030, according to the report. Adopting the maximum technically feasible methane reductions by 2030 would cost about $127 billion annually. 

“Methane mitigation remains one of the smartest climate investments we can make, with benefits far exceeding the cost,” said Martina Otto, head of UNEP’s Climate & Clean Air Coalition, in a press conference. “Cost-effective solutions exist today, waiting to be brought to scale, and the benefits are enormous.”

—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.

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

Cirrus clouds—the wispy, high-altitude ice clouds—are critical players in Earth’s climate. They form in two main ways: anvil cirrus spread out from large storm systems, while in-situ cirrus form on their own, high in the quiet atmosphere. Telling these two types apart on a global scale has been a long-standing challenge.

Using an innovative method that applies computer vision to satellite data, Mu et al. [2025] create the first global maps that cleanly separate these cloud types. The analysis reveals a surprising connection across the planet: powerful storm systems in one half of the world generate massive atmospheric waves that travel across the equator, significantly influencing the formation of in-situ cirrus in the opposite hemisphere.

This discovery highlights how interconnected our climate is and confirms that the two cirrus types are governed by different rules. Anvil cloud amount is driven by storm activity in its own hemisphere. In contrast, in-situ cloud formation, while dependent on local conditions, is also clearly controlled by major storms thousands of miles away. This newfound coupling is vital for climate models to accurately predict how shifting storm patterns under global warming will reshape our future climate.

 Citation: Mu, Q., Ge, J., Huang, J., Hu, X., Peng, N., Li, Y., et al. (2025). A new classification of in situ and anvil cirrus clouds uncovers their properties and interhemispheric connections. AGU Advances, 6, e2025AV001919. https://doi.org/10.1029/2025AV001919

—Donald Wuebbles, 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.

Central Asia’s Pamir Mountain Range contains some of the most well-preserved glaciers in the world.

Obtaining cores from a Pamir region glacier has been “almost like a holy grail for ice core scientists,” said Stanislav Kutuzov, a glaciologist at Ohio State University. But logistical challenges thwarted past attempts.

“The scientific community has been trying to take an ice core from this region for a long time.”

Last month, scientists finally did it: Between 27 September and 1 October, 13 researchers successfully drilled three ice cores from Tajikistan’s Kon Chukurbashi ice cap, a glacier 5,800 meters (19,029 feet) above sea level. Researchers expect the cores to contain ice more than 10,000 years old. The cores preserve important climate information that will help scientists better understand glacier evolution and past climate and weather patterns in central Asia.

“I’m still in disbelief that the expedition happened,” said Evan Miles, the expedition’s leader and a glaciologist at the Universität Zürich and the Universität Freiburg. “The scientific community has been trying to take an ice core from this region for a long time.”

The Tajik government formally donated the cores to the international scientific community in a 13 October ceremony. The cores are the first deep, high-elevation, uninterrupted ice archive to be collected in the Pamir region in Asia’s highlands—dubbed Earth’s “Third Pole” for its ice-, snow-, and glacier-covered landscape. 

“In the whole region of high-mountain Asia, there is not very much climate information available for longer periods into the past,” said Christoph Mayer, a glaciologist at the Ludwig-Maximilians-Universität München who was not involved in the expedition. With the core, “we can fill a really big research gap in this region,” he said. 

A Pamir Core at Last

Scientists have wanted additional glacial cores from this region both because of the region’s long-term, somewhat anomalous stability and because such cores could help them better describe the region’s weather patterns, such as the winter westerly winds that bring moisture to the Pamir range and influence the hydrology of a basin supplying water to millions of people.

Most efforts to obtain Pamir region cores targeted Vanch-Yakh Glacier (formerly Fedchenko Glacier) in Tajikistan. At about 75 kilometers (47 miles) long and more than 1,000 meters (3,281 feet) deep, Vanch-Yakh Glacier was a very desirable object of study. 

But the complex terrain surrounding Vanch-Yakh Glacier means it is extremely hard to reach. Since the 1980s, problems with helicopters, difficult-to-obtain permits, and geopolitical tensions have repeatedly thwarted scientists attempting to drill cores there.

Kon Chukurbashi provided an alternate opportunity. This glacier is accessible by road and foot, no helicopter needed.

The international expedition to Kon Chukurbashi was led by the Swiss Polar Institute’s PAMIR Project in partnership with the Ice Memory Foundation and included researchers from the Academy of Science of Tajikistan, Hokkaido University, Nagoya University, and Ohio State University; local porters; drivers; and a media team. The team left to retrieve the ice cores on 14 September.

The expedition began with a 4-day drive on the bumpy Pamir Highway, one of the world’s highest-elevation roads. Researchers required multiple days of acclimatization, first in the Tajik village of Karakul, then at a 5,100-meter-high (16,732-foot-high) base camp, to safely function at the high altitudes. The team carried roughly 1.5 tons of equipment up to the glacier.

“It’s a risky operation every time. We were fortunate.”

The expedition faced additional challenges, Miles said: There were moments when it looked as though permits might not be issued, cars broke down in the middle of nowhere, and a couple members of the team suffered from acute mountain sickness.

In the final year of funding for their project, the expedition was “make or break,” Miles said. But the team succeeded and carried three ice cores—two about 105 meters (345 feet) long and one shallow 22-meter (72-foot) core—in freezer boxes down from the glacier. They also successfully installed instrumentation to monitor the glacier’s future mass changes and completed a radar survey to determine its internal structure.

After extraction, data from the Kon Chukurbashi ice cores were logged, and researchers took notes on structural changes, dust or rock inclusions, and core quality. Credit: © Jason Klimatsas

“It’s a risky operation every time,” said Kutuzov, who was also the team’s lead driller. “We were fortunate.”

Miles and Kutuzov both said they were impressed with the way the international group was able to work together. “It is only due to the resolve and collaborative nature of our team that we managed to find ways forward and continue,” Miles said. Kutuzov found the international collaboration especially encouraging amid the current dearth of federal support for science in the United States. 

Probing the Pamir’s Climate History

The three ice cores will eventually travel to three continents for safe storage and study.

One is in the custody of the Ice Memory Foundation, an international organization aiming to collect, save, and manage ice cores from glaciers in danger of degradation or disappearance. The foundation runs a heritage collection of ice cores that it plans to store in Antarctica at Concordia Station, a French- and Italian-run research station, starting in December. (The core is currently in Japan, awaiting travel to Antarctica.) The Ice Memory Foundation provided funding that allowed the expedition team to drill multiple cores rather than one.

The Ice Memory core will be preserved for future generations of scientists who may develop techniques to gather information from the ice that today’s methods aren’t able to access. “It’s a brilliant initiative,” Mayer said.

The second deep core, also currently in Japan, is headed to Hokkaido University, where scientists will investigate long-held questions about weather and climate in central Asia.

“We have huge questions on the paleotimescale, the multiple thousands of years timescale about glaciation fluctuations across this region,” Miles said.

Evan Miles inspects a short ice core segment for rock and dust inclusions before it is packed for transport. Credit: © Jason Klimatsas

For one, the drivers behind the unique stability of the region’s glaciers compared to the rest of Asia, a phenomenon dubbed the Karakoram Anomaly, have long been a mystery to scientists. It’s clear from satellite data that the anomaly has persisted since about 1970, but scientists don’t know whether it existed before then. Glaciers in the region also have begun to show signs of melting in the past few years, also raising questions about whether the pattern is truly anomalous or simply a result of natural climate variability.

“We really lack the in situ data to understand even the mechanisms by which this anomaly has happened. We are relying almost solely on remote sensing data,” Miles said.

“We have modeling, we have reanalysis, but no actual data,” Kutuzov added. 

The new Pamir cores may be able to determine whether the anomaly has occurred in the past, as well as its possible source—one untested hypothesis posits that perhaps an increase in irrigation in the valleys below contributed to an increase in the region’s precipitation and stabilizing the glaciers, for example. “There’s a scientific puzzle,” Kutuzov said.

“Maybe [the anomaly] is a frequent thing that happens every so many decades or centuries,” Mayer said. “That would be something very interesting to understand.”

The cores will also give insight into the past climate and weather patterns governing the region, which will provide context to understand the current weather and climate dynamics that affect the region’s hundreds of millions of people.

“Society is going to have to grapple in the coming decades with rather dramatic changes to the hydrosphere, including the cryosphere. And this is, I think, where we can provide really useful information,” Miles said.

The third, shallow core also traveled to Japan after the expedition but will eventually head to Ohio State University, where it will be used to test new research methodologies.

The expedition and the research it allows honor the United Nations Decade of Action for Cryospheric Sciences and International Year of Glaciers’ Preservation.

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

17 November, 2025: This article was updated to reflect the correct date of the beginning of the expedition.

Citation: van Deelen, G. (2025), Pamir glacier expedition returns with high-elevation ice cores, Eos, 106, https://doi.org/10.1029/2025EO250427. Published on [DAY MONTH] 2025. 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.

This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

Una estalagmita en una cueva de Yucatán ha proporcionado una nueva percepción del rol que la sequía puede haber jugado en los cambios sociopolíticos Mayas hace más de 1,000 años. Un análisis reciente de un proxy de precipitación en las tierras bajas Mayas reveló que varios episodios de sequía severa y prolongada durante el Período Clásico Terminal Maya (aproximadamente 800-1000 CE), un período en el que los grandes centros urbanos experimentaron cambios sociopolíticos importantes.

Los investigadores sugieren que, así como el cambio climático actúa como un multiplicador de amenazas hoy en día, la sequía puede haber amplificado los problemas existentes en los centros políticos Mayas como Chichén Itzá y Uxmal, añadiendo estrés climático a las sociedades que ya estaban bajo presión.

“Estos eventos climáticos habrían afectado a cada sitio individual de una manera muy específica dependiendo de la resiliencia de ese sitio en ese momento”, afirmó el investigador principal Daniel James, quien estudia la reconstrucción paleoambiental en la Universidad London College. “Esperamos que la precisión de este registro permita que [el análisis] se realice en sitios individuales … entonces podremos realmente comenzar a construir una imagen de lo que estoy seguro será una amplia variedad de respuestas sociales al cambio climático a lo largo del tiempo y a lo largo de la región”.

Sequías Extendidas Durante las Temporadas Húmedas

Durante el Período Clásico Terminal Maya, varias ciudades-estado Mayas en las tierras bajas del sur (en la actual México, Belice y Guatemala) experimentaron agitación sociopolítica, abandono de sitios y despoblación. Los centros políticos y culturales cambiaron hacia el norte. Aunque los cambios sociales están claros en el registro arqueológico, aún existe un debate generalizado sobre los posibles impulsores de estos cambios, así como por qué algunas ciudades-estado sobrevivieron, mientras otras no.

Este mapa de las tierras bajas Mayas en Yucatán marca sitios de estudios paleoclimáticos previos con cuadrados blancos, con el sitio de este estudio, Grutas Tzabnah, marcado con una X. Mientras que los círculos blancos denotan sitios de las Tierras Bajas del Norte Maya, y las estrellas denotan sitios de interés para este estudio. La tierra está sombreada con base en su elevación en metros sobre el nivel del mar (msnm). Los contornos azules delinean las precipitaciones totales anuales medias modeladas de 1979 a 2022, en milímetros por año. Crédito: James et al., 2025, https://doi.org/10.1126/sciadv.adw7661, CC BY 4.0

La sequía surge a menudo en estos debates como un potencial desestabilizador: las lluvias insuficientes o impredecibles pueden dar lugar a inestabilidades alimentarias, interrupciones comerciales, enfermedades e incluso conflictos militares. Sin embargo, estudios paleoclimáticos previos fallaron en precisar los momentos y la duración de las sequías en las tierras bajas Mayas durante el Período Clásico Terminal, dijo James.

James y sus colegas caminaron a una cueva llamada Grutas Tzabnah, en el estado de Yucatán, México, ubicada cerca de varios grandes sitios Mayas Clásicos, incluidos Chichén Itzá y Uxmal. Esta cueva ha sido buscada previamente para estudios de paleoclima de la región debido a su accesibilidad y las formaciones de cuevas bien conservadas. Además, Grutas Tzabnah es también una cueva relativamente poco profunda, lo que significa que el agua no tarda mucho en gotear en la cueva desde el nivel del suelo.

Los investigadores eligieron una estalagmita que ha estado creciendo por miles de años y muestra distintas capas de crecimiento anual. Esta estalagmita en particular creció rápido en las capas que datan del Período Clásico Terminal Maya, dijo James, entonces el equipo fue capaz de colectar 10-20 puntos de datos dentro de cada capa anual para determinar la precipitación subanual y estacional.

Los investigadores Daniel James (izquierda), Ola Kwiecien (centro) y David Hodell (derecha) instalan un automuestreador de agua por goteo en las Grutas Tzabnah para analizar los cambios estacionales en la química del goteo. Crédito: Sebastian Breitenbach, 2022

“Tú puedes ver temporadas húmedas y temporadas secas en nuestro registro, mientras que los registros previos de la misma cueva están viendo la precipitación media anual”, dijo James. “La precipitación de la temporada húmeda es la que determina el éxito o el fracaso de la agricultura, a diferencia del promedio anual”.

Ellos midieron la edad de las capas empleando datación radiométrica de uranio-torio y la cantidad de precipitación usando una relación isotópica estable de oxígeno, O dentro de la calcita. Las muestras de estalagmita que registraron un bajo O indican más precipitación, mientras que las O más altas indican menos precipitaciones. El equipo calibró sus cálculos paleoclimáticos con mediciones modernas de agua de lluvia y goteo de cuevas en unos pocos años para asegurarse de que podían convertir las mediciones de O de la estalagmita a precipitaciones.

De 871 a 1021, la estalagmita registró ocho sequías extremas durante las temporadas húmedas, cada una con una duración de al menos 3 años. Una sequía de 4 años que inició en 894 fue interrumpida por un solo año húmedo y fue seguida por otros 5 años de sequía de temporada húmeda. Unas décadas más tarde, la región había experimentado 13 años consecutivos de sequía en la temporada húmeda (929–942), más larga que cualquier sequía multianual de los registros históricos locales. Esta investigación fue publicada en Science Advances en agosto.

“La cronología hace de este uno de los registros de paleoclima más detallados disponibles para comprender las interacciones entre humanos-clima durante el período de colapso Maya.”

“Este nuevo estudio representa un avance significativo en nuestra comprensión de los patrones de sequía del Clásico Terminal, principalmente debido a su excepcional resolución temporal y robusto control de la edad con incertidumbres de solo unos pocos años”, dijo Sophie Warken, quien estudia los espeleotemas y variabilidad climática en la Universidad Heidelberg en Alemania y no participó en esta investigación.

“Este enfoque de alta resolución permite a los autores examinar el momento y la duración de los episodios de sequía individuales con mucha precisión, los cuales estudios previos solo pudieron identificar como amplios períodos de desecación”, agregó Warken. “La cronología hace de este uno de los registros paleoclimáticos más detallados disponibles para comprender las interacciones entre humanos-clima durante el período del colapso Maya.”

Una pieza del Rompecabezas

Mientras que este registro de precipitaciones es un gran avance, Warken dijo que le gustaría verlo verificado usando proxies adicionales como elementos traza, así como un período de calibración moderno más largo. También, a ella le gustaría ver este registro extendido antes y después del Período Clásico Terminal para evaluar si esas sequías fueron realmente excepcionales para la región.

“Estas redes paleoclimáticas ampliadas también podrían proporcionar importantes líneas de base para evaluar los cambios climáticos recientes y futuros en esta región vulnerable”, agregó ella.

A pesar de que las sequías prolongadas coinciden con los principales cambios sociales, James advirtió que esto no significa que la sequía causara estos cambios o que fuera incluso el factor más importante.

“Otras dificultades como la hambruna, la enfermedad y la violencia interna podrían haber sido causadas por la sequía o, de hecho, podrían haber existido previamente y haber hecho que la sociedad fuera más susceptible y menos preparada para las dificultades climáticas”, dijo James.

“Me encantaría que estos datos se utilicen para separar historias individuales de sitios individuales de resiliencia y supervivencia, así como también las historias de desintegración de sistemas y abandono y pérdida de población.”

Es importante destacar que la evidencia arqueológica sugiere que dos ciudades Mayas cercanas a esta cueva, Chichén Itzá y la capital regional de Uxmal, no declinaron al mismo ritmo (Uxmal declinó mucho más rápido). Comprender las presiones que experimentaron las dos ciudades, incluida la sequía, será clave para crear una imagen holística de cómo funcionaron las ciudades durante el Período Clásico Terminal.

“Mientras que el estrés climático probablemente jugó un papel importante en las transformaciones del Clásico Terminal”, dijo Warken, “la respuesta de los Mayas a la sequía fue probablemente mediada por las vulnerabilidades sociales, políticas y económicas existentes que variaron entre diferentes centros y regiones”.

“Esto podría deberse a lo bien gobernados que estuvieron, cuán rígido o flexible era su sistema político o qué tan buena era su gestión del agua en ese momento”, dijo James.

“Me encantaría que estos datos se utilicen para separar historias individuales de sitios individuales de resiliencia y supervivencia, así como también las historias de desintegración de sistemas y abandono y pérdida de población”, añadió.

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Escritora Asociada

This translation by Solange Fiallos Ayala (@sol_fiallos_ec) was made possible by a partnership with Planeteando. Esta traducción fue posible gracias a una asociación con Planeteando.

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.

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

Satellite company Blacksky has released a high resolution satellite image, captured on 12 November 2025, showing the aftermath of the 11 November 2025 landslide at Hongqi Bridge in China. The image was captured by their Gen-3 instrument, and distributed via Twitter:-

The aftermath of the 11 November 2025 landslide at Hongqi Bridge in Sichuan Province, China. Image captured by Blacksky and released via Twitter.

On Reddit, there is a good short video of the site too, which includes this still:-

The aftermath of the 11 November 2025 landslide at Hongqi Bridge in Sichuan Province, China. Still from a video posted to Reddit.

This is a rock slope landslide with several metres of movement on the back scarp. Essentially the rock spur has failed. On one side (the left on the photograph above) the slope has collapsed down to the level of the lake (and probably below), whilst the main mass has a lower level of displacement (although I suspect that the failure is still through the mass to below the lake). It appears that the tunnels remain largely intact. The main part of the cantilever bridge has performed well, with the largest piers and their bridge decks remaining intact. However, the missing section is going to be very challenging to replace.

It appears that filling of the lake might have been suspended (satellite imagery shows no change in the level since the landslide occurred). One hopes that this is to allow a reappraisal of the stability of the slopes along the reservoir banks. I would be particularly concerned about those slopes that have had excavations close to the current level of the lake. There will also be some concern about the stability of this landslide. Is it possible that further filling of the lake could induce a further collapse, endangering the main bridge pillars?

Acknowledgement

Many thanks to loyal reader Alasdair for finding the image and the video.

Return to The Landslide Blog homepage Text © 2023. 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.

Source: Journal of Geophysical Research: Earth Surface

Arctic coastlines are falling into the sea. Wave action, rising sea levels, and thawing permafrost are all contributing to the massive erosion that has forced whole towns to move farther from the water’s edge.

To understand how these forces combine to bring down cliffs, Omonigbehin et al. created a microcosm of an Arctic coastline in a lab. First, the researchers mimicked soil containing permafrost by mixing water and sand in ratios designed to maximize the density of the sand, then compacting the mixture with a hydraulic press and freezing it. The researchers pummeled these blocks of faux permafrost with water in a cooled wave flume, a long and narrow tank in which waves are generated so researchers can observe their effects. In this study, the scientists varied the wave height and frequency to see how the permafrost would respond.

The method reproduced observed patterns of erosion that hollow out the bases of coastal bluffs. Wave height had the strongest influence on the rate of erosion, with the highest-wave conditions causing twice as much erosion as low-wave conditions. Wave frequency, on the other hand, strongly influenced the height of the notch carved out by the waves.

When the researchers increased the ice content in the soil by adding more water prior to freezing, they found that the higher ice content decreased the initial erosion rate (because the ice took longer to thaw). This finding suggests that coastlines with higher ice content that currently appear stable may not see high erosion rates in the immediate term but could erode abruptly if the current global warming rate is sustained—a finding that’s consistent with the theory that climate change will trigger tipping points. However, the researchers caution that more research is needed to confirm this finding. (Journal of Geophysical Research: Earth Surface, https://doi.org/10.1029/2025JF008528, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), Lab setup mimics Arctic erosion, Eos, 106, https://doi.org/10.1029/2025EO250422. Published on 14 November 2025. 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.

More than 75 million people work in the garment industry, many of them in the world’s hottest countries. As climate change warms the air and oceans, so too does it seep into the stuffy chambers of garment factories, where conditions are highly uncomfortable if not downright unsafe.

In research recently published in The Lancet, scientists tested different interventions for protecting workers from rising temperatures in Bangladesh, a nation where 80% of its export revenue comes from the garment industry. The 4 million Bangladeshi people, mostly women, who sew ready-made garments often work 12-hour shifts 6 days a week in humid and poorly ventilated buildings. Prolonged heat stress can put strain on their cardiovascular systems and increase their risk of heat stroke, especially because many workers have existing kidney and cardiovascular issues.

“I think it’s really important that we get ahead of the curve and start identifying solutions…that are both effective in today’s climate, but also future-proof.”

“Bangladesh has already been identified as one of the most climate-change-vulnerable countries in the world,” said lead author James Smallcombe, a thermal physiologist at the University of Sydney. “I think it’s really important that we get ahead of the curve and start identifying solutions…that are both effective in today’s climate, but also future-proof.”

His team began by outfitting a factory in Bangladesh with temperature and humidity sensors to determine hot spots that might respond to building-level changes. They then re-created the factory conditions inside a climate-controlled chamber, where volunteer participants conducted factory work while having their physical health and productivity assessed.

Here are the most promising solutions from the study.

1. Green and White Roofs

Most factory roofs in Bangladesh are made of hard concrete or sheet metal, both of which trap heat.

Friendlier “green” roofs require planting a layer of vegetation on top, and “white” roofs involve applying a layer of reflective white paint. While white roofs are cheap to retrofit, green roofs require more installation and maintenance costs—resources that, in turn, contribute to enhancing biodiversity and storing carbon.

Factory owners are often reluctant to make such capital investments, especially in an era of tariffs and economic uncertainty. If they do, however, such building-level changes can lower indoor heat by a dramatic 2°C–3°C (3.6°F–5.4°F) and reduce individuals’ core temperature, heart rate, and level of dehydration.

2. Electric Fans

While air conditioners (ACs) are nearly ubiquitous in the United States, they are hardly a global panacea due to their high costs and energy demands. Electric fans may solve both of ACs’ ills, but they improved only physical comfort in the study, not physiological strain.

Using fans as cooling devices can be deceptively tricky, explained environmental physiologist George Havenith of Loughborough University, United Kingdom: At temperatures above 43°C (109°F), fans push heat onto the skin more than they help evaporate sweat.

Havenith, who was not a part of the new study, noted that fans with a water spray function can also cool the body, as can combining normal fans with wet clothing—known as the “wet T-shirt method” of alleviating heat stress. A major benefit of fans is that they can direct airflow to particularly vulnerable areas of a factory, such as stations where ironing and steaming create extra heat.

3. Water Breaks

One of the best ways to cool the body is from the inside out. Researchers found that taking a water break once or twice an hour lowered participants’ core temperatures, heart rate, level of dehydration, and discomfort when paired with an electric fan.

However, noted Vidhya Venugopal, an occupational and environmental health researcher at the Sri Ramachandra Institute of Higher Education and Research in Chennai, India, garment workers are typically paid at a per-piece rate, making them reluctant to take breaks and receive less income. Even if employers distributed water to each station, she said, many factories lack bathroom facilities, meaning workers would have nowhere to relieve themselves. Venugopal was not involved in the new research.

“We have the scientific evidence to prove that these things can work. The main challenge is, How do we get them into a policy framework?”

Notably, the break helps more if it’s in a cooler location, said Dung Phung, a public health scientist at the University of Queensland who was not involved in the study. His own research in Thailand showed that lumber workers’ health improved after taking breaks under trees or in a cool house.

Ultimately, said study coauthor Fahim Tonmoy, a climate change adaptation researcher at Griffith University in Australia, “we have the scientific evidence to prove that these things can work. The main challenge is, How do we get them into a policy framework?”

The team hopes their findings on productivity may move the needle; unmediated heat stress lowered workers’ efficiency so much that even taking breaks improved their output. Tonmoy also said clothing companies can create incentives by buying only from factories that implement such solutions.

As temperatures in Southeast Asia “get hotter by the day,” said Venugopal, making changes will only become more vital. “We are not talking about a few people,” she said. “We are talking about millions and millions.”

—Hannah Richter (@hannah-richter.bsky.social), Science Writer

Citation: Richter, H. (2025), Garment factories are heating up. Here’s how workers can stay cool, Eos, 106, https://doi.org/10.1029/2025EO250425. Published on 14 November 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.

As tectonic stress is released during an earthquake, rock slips, and Earth’s crust is damaged, like a wound to the skin. And like skin, the scar-like wounds left after an earthquake can heal, and the impacted area can recover its strength over time. A study published in Science indicates that such recovery may be limited to only the upper crustal layers. The deep crust takes much longer to recover—or possibly doesn’t recover at all.

Lasting Change to the Deeper Crust

The findings stemmed from what was meant to be only a test of a new technique.

Jared Bryan, a geophysicist at the Massachusetts Institute of Technology (MIT) and first author of the new study, was refining a method to investigate localized damage to Earth’s crust by measuring the speed at which seismic waves generated by distant earthquakes pass through it.

Bryan wanted to use the technique to study volcanoes, but as a test, he turned to California’s 2019 Ridgecrest earthquake sequence—a magnitude 6.4 foreshock followed by a magnitude 7.1 main shock. “What brought me originally to working on the Ridgecrest fault zone was just that I wanted an obvious signal that I could use to calibrate my technique,” Bryan said. Conveniently, the region had readily available seismic wave data from 34 permanent seismic stations within 74 miles (120 kilometers) of the fault zone.

Between 2015 and 2023, 5,500 earthquakes generated seismic signals that traveled through Earth’s crust and arrived vertically at the seismic stations, allowing the team to track the seismic wave velocities before and after the Ridgecrest earthquake. Earthquake damage creates fractures in the rock, measurably slowing seismic waves passing through it. After the test, Bryan planned to use the technique to study volcanoes. But the results were too intriguing to abandon.

Previous studies of earthquake damage were limited to the shallow crust, typically less than 6 miles (10 kilometers) down, or averaged the results across all depths.

“You could never tell where those changes really were a function of depth, and that’s crucial,” said geophysicist Roland Bürgmann from the University of California, Berkeley, who wasn’t involved in the study.

The technique researchers used in the new study, however, detects changes equally well throughout the entire crustal column, from the surface down to 15 miles (25 kilometers). “What we were most excited about was using this method that allows us to image how things change in the Earth beyond the depth that we typically think about doing that sort of work,” said William Frank, a geophysicist at MIT and coauthor of the study.

Tracking the seismic waves passing through the crust around the Ridgecrest earthquake, the researchers saw that in the upper crust, waves slowed, then returned to normal within months, indicating the crust had, indeed, been damaged but had recovered.

The finding that the lower crust experiences slow, evolving, and enduring damage is “completely new and novel.”

However, seismic waveform data from deeper down, between 6 and 9 miles (10 and 15 kilometers), indicated that the damage accumulated more slowly and did not heal over the 3-year-plus time span analyzed after the quake. Bryan said that data showing changes to waveforms are usually subtle, requiring careful quantification, but that was not the case with data from the deeper crust. “I could see, visually, this permanent change at the time of the earthquake,” he said.

Bürgmann said that the finding that the lower crust experiences slow, evolving, and enduring damage is “completely new and novel.”

Looking Beyond Ridgecrest

The scientists suggest two possible outcomes for damage to the deep crust. Either the damaged area will recover, albeit over decades or centuries rather than months, or the changes will be permanent, and the fault zone’s structure will progressively shift with each earthquake.

Since the Ridgecrest region has not experienced as many earthquakes as more mature fault zones, it’s possible “we’re watching these fault zones mature in real time,” Bryan said.

The team wants to apply the same method to more mature faults like the well-studied San Andreas zone to the west. If data indicate the deeper crust of a mature fault zone heals after an earthquake, the lasting damage at Ridgecrest could be a characteristic of fault evolution.

Research on recovery in the deep crust is “going to place important constraints on how we model that evolution and how that then impacts our future forecasts of where and how earthquakes might happen,” Frank said.

—Andrew Chapman (@andrewchapman.bsky.social), Science Writer

Citation: Chapman, A. (2025), The Ridgecrest earthquake left enduring damage in Earth’s deep crust, Eos, 106, https://doi.org/10.1029/2025EO250421. Published on 14 November 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.

A large landslide has destroyed a 662 m long highway viaduct in China.

Over the last two days there has been considerable media coverage of a large, highly destructive rockslide that occurred at Hongqi Bridge in Sichuan Province, China. There is a very interesting set of images of the bridge during construction on the Highest Bridges site – the bridge was 662 metres long with pillars 172 m high, constructed to divert the G317 road as a result of the construction of the 312 m high Shuangjiangkou Dam.

The location of Hongqi Bridge is [31.82084, 101.90537]. The road exits a tunnel on a steep slope on the east side of the river, crossing via the bridge, and then enters another tunnel on the west side.

This is a video of the landslide:-

This is clearly a rockslide that has destroyed the pillars on the west side of the channel. It is interesting to see the amount of dust being generated. Note that there is a lot of false information circulating about this collapse, including AI generated videos and footage from other sites.

Reports suggest that cracks were noted in the slope and in the structures on 9 November 2025, with the road being closed the following day. The rockslide occurred on 11 November 2025.

This Google Earth image shows the site before construction of the bridge started:-

Google Earth image from 2010 of the site of Hongqi Bridge in Sichuan Province, China.

First inspection of that site suggests that it is immensely challenging from an engineering geomorphological perspective. There are hints of palaeo-landslides, fractured rock masses and loose deposits in a very steep, active topography.

Impoundment of water started on 1 May 2025, and satellite images suggest that the water level has been rising rapidly. Landslides during first impoundment are common – Three Gorges for example suffered many examples. The video suggests that the initial large scale failure might have occurred just above the road level, where the slopes have been excavated to create the road platform. This then propagated both downslope and upslope.

At this stage, the failure might be attributed to some combination of increased groundwater levels and poor engineering design / construction, especially with respect to the cut slopes.

The engineers now face two problems. First, reinstating this key road is going to be extremely challenging and time consuming. The highway has to cross this gorge, which of course will have been flooded. This will be a long and very expensive operation.

Second, as impounding continues, are there other potentially unstable slopes? An abundance of caution is needed given the height of the dam.

Return to The Landslide Blog homepage Text © 2023. 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.

Source: AGU Advances

Earth’s largest mass extinction occurred around 252 million years ago, wiping out the majority of marine and terrestrial life, disrupting the global carbon cycle for several hundred thousand years, and earning the title “the Great Dying.” Global warming, changing temperature gradients, shifts in nutrient cycling, and oxygen depletion wiped out 81% of all marine life at the time.

But cooler, relatively high latitude marine environments may have been refuges for species escaping volatile climate conditions elsewhere. Buchwald et al. examined rock samples from the Arctic archipelago of Svalbard, Norway, and identified high levels of lipid biomarkers in rocks dated soon after the Permian-Triassic extinction. Though the exact organism producing these molecules is unknown, it is likely a group of phytoplankton. This finding suggests that the cooler waters of the paleo-ocean allowed this primary producer to bloom and sustain remaining sea life.

The researchers collected 32 rock samples from Svalbard taken from layers formed pre- and postextinction and compared them with samples taken from other locations, such as northern Italy, southern China, and Türkiye. All represent warmer regions surrounding the prehistoric Tethys Ocean, a precursor to the modern Indian Ocean and Mediterranean Sea. The team examined the samples for C33–n-alkylcyclohexane (C33–n-ACH) and phytanyl toluene, molecular fossils that act like fingerprints of ancient marine life.

In the Svalbard samples dated after the Permian-Triassic extinction event, C33–n-ACH levels were 10 times higher than in samples from before the event. The researchers note that the preextinction samples likely experienced more degradation, but that alkylcyclohexane biomarkers are relatively resistant to such degradation, meaning the higher amounts detected after the extinction point to a true increase in the biomarker. In the samples taken from warmer regions, far less C33–n-ACH overall was detected, but a similar increase in abundance after the extinction event occurred.

Phytanyl toluene was largely absent from the Svalbard samples before the extinction and showed a similarly dramatic increase in the extinction’s aftermath. It was not present in the tropical samples, suggesting that it was produced by a different phytoplankton than the species that produced the C33–n-ACH.

Overall, these findings suggest that the phytoplankton producers of these biomarkers remained stable and thrived in cooler waters during a time when warmer waters were unable to support significant marine life, the researchers say. (AGU Advances, https://doi.org/10.1029/2025AV001785, 2025)

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

Citation: Owen, R. (2025), How algae helped some life outlast extinction, Eos, 106, https://doi.org/10.1029/2025EO250426. Published on 13 November 2025. 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.

Where Science Connects Us

This month, Eos is meeting the moment “Where Science Connects Us” with deep dives into the state of the geoscience profession (“Eight Ways to Encourage Equality, Diversity, and Inclusion Discussions at Conferences”) and some ATLAS-sized enthusiasm for a comet (“How an Interstellar Interloper Spurred Astronomers into Action”), as well as research updates (“Tracing Black Carbon’s Journey to the Ocean”) and quirky queries (whither Planet Y.)

AGU’s annual meeting is in New Orleans this year, and our feature story, a forward-looking analysis of the ways hurricane forecasting has grown in breadth and depth since Hurricane Katrina, is a great read for those attending AGU25. It’s a great read for those who aren’t at the meeting, too—a reminder of the relevance and importance of Earth and space sciences for discovery and solution-based inquiry.

So follow the path of the Mighty Mississippi as you let Eos show where science connects us to Earth, space, and each other.

—Caryl-Sue Micalizio, Editor in Chief

Citation: Micalizio, C.-S. (2025), Where science connects us, Eos, 106, https://doi.org/10.1029/2025EO250423. Published on 13 November 2025. 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.

Abstract

To meet the high-precision and high-integrity positioning demands of safety–critical applications, monitoring the quality of precise satellite products in global navigation satellite system (GNSS) precise point positioning (PPP) is crucial. This work employs ionosphere-free (IF) PPP with ambiguity resolution (PPP-AR) phase residuals to construct test statistics for monitoring the quality of precise satellite corrections. By utilizing precise satellite orbit and clock products from CODE, WUM, and GRG, the PPP-AR phase residuals were first analyzed with sample moments, Allan variance and power spectral density (PSD). The key findings are as follows: (1) The skewness and kurtosis results indicate that ambiguity-fixed phase residuals deviate from an ideal zero-mean Gaussian distribution and exhibit a super-Gaussian distribution. (2) Allan variance and PSD analysis reveal that flicker noise dominates the phase residuals. (3) The noise amplitudes are similar for all satellites, but certain differences are observed among different GNSS systems and satellite types. (4) The noise level of phase residuals is influenced by the receiver types, antenna types, and precise products from different analysis centers. Leveraging the error characteristics, the two-step Gaussian overbounding (OB) method was employed to estimate the corresponding OB parameters of the phase residuals. The overbounding results demonstrate that, under similar conditions, phase residuals can be bounded by the calculated bound within the acceptable integrity risk after removing the detected outliers. Anomaly monitoring experiments further show that phase residuals can effectively capture anomalies in precise satellite corrections, with the set threshold successfully detecting such anomalies.

The measurement of virtual height of the sporadic E layer (h'Es) is very sensitive to the type of ionosonde used and the calibration processes. The ionosondes used by the national institute of communication an...

Abstract

Solar photospheric abundances and CI-chondrite compositions are reviewed and updated to obtain representative solar system abundances of the elements and their isotopes. The new photospheric abundances obtained here lead to higher solar metallicity. Full 3D NLTE photospheric analyses are only available for 11 elements. A quality index for analyses is introduced. For several elements, uncertainties remain large. Protosolar mass fractions are H (X = 0.7060), He (Y = 0.2753), and for metals Li to U (Z = 0.0187). The protosolar (C+N)/H agrees within 13% with the ratio for the solar core from the Borexino experiment. Elemental abundances in CI-chondrites were screened by analytical methods, sample sizes, and evaluated using concentration frequency distributions. Aqueously mobile elements (e.g., alkalis, alkaline earths, etc.) often deviate from normal distributions indicating mobilization and/or sequestration into carbonates, phosphates, and sulfates. Revised CI-chondrite abundances of non-volatile elements are similar to earlier estimates. The moderately volatile elements F and Sb are higher than before, as are C, Br and I, whereas the CI-abundances of Hg and N are now significantly lower. The solar system nuclide distribution curves of s-process elements agree within 4% with s-process predictions of Galactic chemical evolution models. P-process nuclide distributions are assessed. No obvious correlation of CI-chondritic to solar elemental abundance ratios with condensation temperatures is observed, nor is there one for ratios of CI-chondrites/solar wind abundances.