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In the ocean, a haze made from tiny bits of dead plants, animals, and microbes hangs in the upper reaches of the water. Each particle is just a fraction of a micrometer across, but together the carbon within these particles weighs about 700 billion tons—about as much as all the carbon in the atmosphere.

For decades, scientists have relied on a chemical fingerprint inside water molecules to determine where plants get their moisture. The method shaped our understanding of drought resilience, groundwater use, and ecosystem survival. But there was a problem. The fingerprints didn't always match.

For years, the Prairie Pothole Region has bothered me in a very specific way. On a map, it looks like a normal landscape: fields, gentle slopes, small streams. But hydrologically, it behaves like something else entirely. The surface is peppered with countless depressions—wetlands and "potholes"—that can store water for days, months, or even years. Most of the time, rainfall and snowmelt do not move cleanly downhill into channels. They disappear into storage. Then, sometimes, they don't.

There are many open questions about how our planet formed 4.55 billion years ago: When did plate tectonics start? When did the Earth's mantle begin to vigorously circulate in a process called convection? What was Earth like early in its lifetime? Because no rock records from the earliest years of the Earth remain, researchers turn to minerals called zircons, which are resilient against physical and chemical alteration over time and therefore preserve a precise chemical record about the moments in which they were formed.

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

The Amazonian forest takes up atmospheric carbon dioxide (CO2), thus helping to buffer the effect of global anthropogenic emissions on climate. As the climate changes, however, this previously reliable carbon sink may be at risk. Extreme weather events, such as the drought of 2023 in the Amazon region, are becoming more common. Although the Amazonian forest is adapted to climatic variation and drought to some extent, severe drought can lead to reduced photosynthesis and greater emissions from fires. Estimating this effect at a scale as large as the Amazon Basin is challenging.

Botía et al. [2026] use multiple approaches that generally show a net release of carbon from the basin during 2023, although there are differences among methodologies. Satellite-based measurements, biogeochemical models, and CO2 concentrations measured at a tall tower indicated a regional net release of carbon, but of varying amounts. A more localized method of tower-based eddy covariance measurements showed a net uptake of CO2, indicating that the local patch of forest was responding differently than the basin-wide estimates. In an accompanying Viewpoint, Liu [2026], these complex responses are nicely explained and summarized by the author.

Citations:

Botía, S., Dias-Júnior, C. Q., Komiya, S., van der Woude, A. M., Terristi, M., de Kok, R. J., et al. (2026). Reduced vegetation uptake during the extreme 2023 drought turns the Amazon into a weak carbon source. AGU Advances, 7, e2025AV001658. https://doi.org/10.1029/2025AV001658

Liu, J. (2026). The growing threat of extreme drought-heat to the Amazon carbon sink. AGU Advances, 7, e2026AV002309. https://doi.org/10.1029/2026AV002309

—Eric Davidson, Editor, AGU Advances

Text © 2026. 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: AGU Advances 

The amount of time that mercury (Hg) spends in the atmosphere determines its global spread, and therefore the distribution of this toxic pollutant, even to remote ecosystems. Generally, previous studies have assumed the chemical lifetime of elemental mercury (Hg0) has been constant throughout history, mirroring the conditions of present-day (2010–2019). However, since pre-industrial times (about 1850), anthropogenic emissions have altered the concentrations of oxidants that affect the lifetime of Hg0, including bromine radicals (Br), hydroxyl radicals (OH), and ozone (O3).

Feinberg et al. [2026] use a state-of-the-art chemistry-climate model to analyze the effects of the changes in background composition between 1850 and now to examine the resulting effects on mercury deposition into water around the world. The increasing concentrations of OH and O3 lead to 16% faster Hg0 oxidation in today’s Northern Hemisphere, while the increased partitioning of Br to reservoir species slows Hg0 oxidation by 20% in the Southern Hemisphere relative to the 1850 atmosphere. These regional oxidation changes shift the pattern of where Hg deposits to the surface.

The shifts in Hg0 oxidation enhance deposition by 15% to tropical and subtropical oceans, which are critical regions for Hg exposure risks. The 1850 atmosphere, however, was more conducive to the spread of Hg to the remote Southern Hemisphere extratropics. This finding significantly affects the interpretation of the Hg deposition historical records from natural archives. This study reveals that the changing atmospheric composition has been a previously overlooked factor when considering human Hg exposure risk via altered Hg deposition patterns. 

Citation: Feinberg, A., Sonke, J. E., Cuevas, C. A., Li, M.-L., Acuña, A. U., Fernandez, R. P., et al. (2026). Shifts in atmospheric composition since the preindustrial era modified the transport and deposition of mercury. AGU Advances, 7, e2025AV002158. https://doi.org/10.1029/2025AV002158

—Don Wuebbles, Editor, AGU Advances

Text © 2026. The authors. CC BY-NC-ND 3.0
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Source: Journal of Geophysical Research: Biogeosciences

In the ocean, a haze made from tiny bits of dead plants, animals, and microbes hangs in the upper reaches of the water. Each particle is just a fraction of a micrometer across, but together the carbon within these particles weighs around 700 billion tons—about as much as all the carbon in the atmosphere.

Dissolved organic carbon (DOC), as these little bits are called, is a food source that sustains marine bacteria and a carbon store with huge implications for climate change. Yet scientists don’t understand what dictates the distribution of DOC throughout the ocean.

Owusu et al. set out to explain the distribution of DOC with a focus on the North Atlantic subtropical gyre, where the concentration of DOC is particularly high. Some scientists have hypothesized that certain hard-to-break-down forms of DOC are sucked into subtropical gyres by strong currents, then remain trapped there long-term. But this team had a different suspicion: The type and number of bacteria present in the gyre dictate how much DOC accumulates.

To test their theory, the researchers used a consumer-resource model to study how bacteria compete for DOC when they have access to varying levels of nitrogen, which can limit bacterial growth. When the researchers varied bacterial prevalence, DOC concentration followed quite naturally, they found. However, the rate at which dead organisms produced DOC did not fully explain the prevalence of DOC. The results are consistent with a recent study in which researchers sampled water from the gyre and found there weren’t enough bacteria around to take advantage of all the DOC they could be munching on.

The findings represent a switch from the long-dominant theory that the biochemical properties of DOC determine how easily it breaks down. The study suggests that the microbial makeup of ocean water is actually the prime deciding factor in how much dissolved organic matter it contains. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2025JG009257, 2026)

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

Citation: Sidik, S. M. (2026), Bacteria decide the ocean’s dissolved organic carbon abundance, Eos, 107, https://doi.org/10.1029/2026EO260072. Published on 3 March 2026. Text © 2026. 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

Atmospheric rivers (ARs) are coherent current structures in the atmosphere that transport moisture and are important elements to deliver water through heavy precipitation events. They can also cause substantial hazards in many regions of the world. Due to their intrinsically long and narrow extent and high variability, it is challenging to observe and detect trends in AR activity and characteristics. Yet, this would be crucial for water resource planning and adaptation strategies.

Based on hourly atmospheric reanalysis data and applying several identification tools, Scholz and Lora [2025] find that the frequency of ARs in mid-latitudes of both hemispheres has robustly increased since 1940. Particularly, in the Southern Hemisphere, over the eastern United States, the North Atlantic region and into western Europe (see Figure), with concurrent increases in precipitation and snowfall. Less obvious surface impacts of ARs are warm winters and extreme heat events.

The longer-term context for AR trends that is established by the authors helps climate model simulations to better assess this important feature of atmospheric circulations and eventually improve projections. These are crucial inputs for decision makers to make water management and hazard prevention fit for the future. However, for example, formal detection and attribution studies on ARs are still challenging due to the large uncertainties associated with this fine-scale feature of atmospheric circulation.

Citation: Scholz, S. R., & Lora, J. M. (2025). Widespread increase in atmospheric river frequency and impacts over the 20th century. AGU Advances, 6, e2025AV001888. https://doi.org/10.1029/2025AV001888

—Thomas Stocker, Editor, AGU Advances 

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The devastating wildfires in northern Canada in recent years have climate consequences that go far beyond smoke and carbon dioxide released into the atmosphere, according to a new study co-authored by two NAU researchers. The study, which looked at the various effects of fire in northern Canada and Alaska, wasn't all bad news: The researchers found fires in Canada, when coupled with snowpack, have a net cooling effect. That cooling, however, isn't enough to outweigh the warming effects of permafrost carbon released into the atmosphere from fires in Alaska.

Author(s): Tomohiro Tanogami, Makoto Sasaki, and Tatsuya Kobayashi

Magnetically confined fusion plasmas exhibit predator-prey-like cyclic oscillations through the self-regulating interaction between drift-wave turbulence and zonal flow. To elucidate the detailed mechanism and causality underlying this phenomenon, we construct a simple stochastic predator-prey model…

[Phys. Rev. E 113, 035201] Published Tue Mar 03, 2026

SummaryThe Mendocino Triple Junction (MTJ), where the Gorda, North American, and Pacific plates meet, is one of the most seismically active regions in California. The tectonic movements along the Mendocino transform fault zone (MTFZ), Gorda slab (GS), and northern San Andreas Fault systems (NSAF) lead to high background seismicity rates but relatively low aftershock productivity. To improve the understanding of earthquake processes in the area, we analyze relations between background seismicity, aftershock productivity, and stress parameters. We apply the nearest-neighbor approach to investigate the spatial distributions and properties of background and clustered seismicity, and invert focal mechanisms of events in Voronoi cells for features of the deviatoric stress field. The results indicate that the intensity of background seismicity and aftershock productivity decrease with distance from the MTJ, defined here for simplicity as the hypocenter of the 1992 Mw7.2 mainshock. We also find that the stress regime is the most compressive in the area directly surrounding the MTJ. In the MTFZ and GS, the compressive stress decreases with increasing distance from the MTJ, correlating with the reduced aftershock productivity and background seismicity. In the NSAF, the observed relations between the stress, aftershock productivity, and background seismicity are not clear, possibly due to crustal extension related to the slab window and elevated heat flow. Compared to the MTFZ and GS, the NSAF has a higher foreshock proportion, lower aftershock proportion, and small-to-medium mainshock magnitudes, indicating more swarm-like clusters in this region. The inverted stress regimes in the MTFZ and NSAF are dominated by strike-slip faulting. The GS exhibits mostly strike-slip and normal mechanisms despite the subduction environment, which may reflect slab bending and reactivation of preexisting normal faults.

SummaryUnderstanding when and where strong earthquakes occur is crucial for assessing seismic hazard. Changes in the b-value, which describes how frequently earthquakes of different sizes happen, have been investigated as possible indicators in the space-time vicinity of upcoming large earthquakes. In this study, we investigate short-term b-value variations in the central-northern Apennines (Italy) by comparing an observed earthquake catalogue spanning the period 1987–2025 with a 10 000-year synthetic catalogue generated by a physics-based earthquake simulator. The synthetic seismicity is produced using a three-dimensional seismotectonic model derived from the DISS database and an elastic-rebound framework for earthquake nucleation. We apply a stacking procedure to compute average b-values within symmetrical time windows of ± 15 days and 30 km distance from selected pivot events of moderate to large magnitude. The same methodology is consistently applied to both observed and simulated datasets, enabling a direct comparison of their temporal behaviour. The observed catalogue shows a statistically significant decrease in the b-value in the days preceding earthquakes with Mw ≥ 4.0, followed by a post-event recovery. A comparable pattern is reproduced by the synthetic catalogue, where a pronounced b-value drop precedes pivot events of Mw ≥ 4.5 and is systematically followed by an increase after rupture. The persistence of this behaviour across different magnitude thresholds in the simulated data supports its robustness. These results indicate that physics-based simulations can reproduce short-term b-value variations associated with earthquake nucleation, supporting the relevance of this parameter for investigating the physical processes governing seismicity.

A research team led by a Keele scientist has shed new light on how a mysterious rock formation in Oman was created, which could reveal new details about Earth's ability to store carbon dioxide (CO2). The study, led by Dr. Elliot Carter in Keele's School of Life Sciences, in collaboration with the Universities of Ottawa and Manchester, looked at geological evidence from Oman to better understand processes that occur in subduction zones, which is where one of Earth's tectonic plates sinks beneath another due to the plates colliding together. This process is active around much of the Pacific "Ring of Fire" today, for example.

The Florida Everglades is a complicated climate actor. The 1.5-million-acre wetland system remains a carbon sink, removing an average of 13.7 million metric tons of carbon dioxide from the atmosphere each year, but the system also releases methane. In a new study, Yale School of the Environment scientists have analyzed the greenhouse gas fluxes in its mangroves and fresh-water marshes, providing a more detailed approach for guiding restoration efforts.

Atmospheric rivers carry unfathomable amounts of water across the sky, bringing moisture to drought-stricken regions like the Western U.S. But whether a particular incoming atmospheric river storm will result in disastrous flooding has long been difficult for researchers to determine with confidence. Now, a new Desert Research Institute-led study demonstrates that accounting for soil saturation levels can substantially improve our early warning of potentially destructive flooding events.

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A new study of Antarctica has found that since 1996, its ice sheet has lost 12,820 square kilometers (nearly 5,000 square miles) of ice—nearly enough to cover the state of Connecticut, or 10 cities the size of Greater Los Angeles.

The study, published today in Proceedings of the National Academy of Sciences, evaluated the retreat of the ice sheet’s grounding line over the past 30 years. A grounding line is the point at which continental ice (grounded on bedrock) meets a floating ice shelf, and as such serves as a good measure of the advance and retreat of ocean-terminating glaciers.

Since 1992, scientists have been monitoring the movement of grounding lines with synthetic aperture radar (SAR), the “gold standard for documenting ice sheet stability,” said Eric Rignot, a glaciologist at the University of California, Irvine, and coauthor of the new paper, in a statement. 

Data from multiple SAR-equipped satellites showed that about 77% of Antarctica’s coastline remains stable, but the unstable portions—West Antarctica, the Antarctic Peninsula, and portions of southern East Antarctica—are losing ice much faster as Earth’s climate warms.

Grounding line changes from 1992-2025 show quicker ice loss along West Antarctica, parts of the Antarctic Peninsula, and southern East Antarctica. Credit: Rignot et al. 2026, https://doi.org/10.1073/pnas.2524380123

Glaciers in West Antarctica have retreated the farthest: In the last 30 years, Pine Island Glacier retreated 33 kilometers (20.5 miles), Thwaites Glacier—often called the Doomsday Glacier for its potential contribution to sea level rise—retreated about 26 kilometers (16.2 miles), and Smith Glacier retreated about 42 kilometers (26.1 miles). 

 
Related

•  Read the paper: Thirty Years of Glacier Grounding Line Retreat in Antarctica
 

“Where warm ocean water is pushed by winds to reach glaciers, that’s where we see the big wounds in Antarctica,” Rignot said. Thwaites and Pine Island glaciers, for instance, began their retreats in the 1940s, when a prolonged El Niño event likely brought warmer-than average temperatures to the Southern Ocean.

Though warm ocean waters mostly explain the retreats along West Antarctica, large retreats along the northeast side of the Antarctic Peninsula are more difficult to interpret, according to the authors. There, “we don’t have evidence for warm water,” Rignot said. “Something else is acting—it’s still a question mark.”

The data provided in the new paper offer future ice sheet scientists critical benchmarks to test how accurate their own models and projections of Antarctic ice loss are, Rignot said. “If a model can’t reproduce this record, the modeling team will need to go back to the drawing board.”

—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 © 2026. AGU. CC BY-NC-ND 3.0
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A comprehensive 30-year study led by University of California, Irvine glaciologists has produced a circumpolar ice grounding line migration map of Antarctica. An amalgamation of three decades of satellite data compiled and analyzed by the researchers revealed that while most of Antarctica remains remarkably stable, vulnerable sectors are losing grounded ice equivalent to the size of Greater Los Angeles every three years.

In the forests of the southeastern United States, dense tree cover dominates most landscapes. That's why the Appalachian Trail is sometimes nicknamed "The Green Tunnel." But avid hikers know that often in the Southeast, they'll emerge from the green tunnel.

Publication date: February 2026

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 279

Author(s):

Publication date: February 2026

Source: Journal of Atmospheric and Solar-Terrestrial Physics, Volume 279

Author(s): Rafath Samrin, Pundru Chandra Shaker Reddy, K. Arun Kumar, Natha Deepthi, C. Mithra, S Bhargavi Latha, Sucharitha Yadala, Gopal Kumar Thakur