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Publication date: 15 January 2026

Source: Advances in Space Research, Volume 77, Issue 2

Author(s): Songhua Hu, Jingshi Tang

Publication date: 15 January 2026

Source: Advances in Space Research, Volume 77, Issue 2

Author(s): Xiangru Bai, Haibo Song, Caizhi Fan

Publication date: 15 January 2026

Source: Advances in Space Research, Volume 77, Issue 2

Author(s): Zhaoyu Li, Tianyou Li, Hao Zeng, Rui Xu

The cycling of water within Earth's interior regulates plate tectonics, volcanism, ocean volume, and climate stability, making it central to the planet's long-term evolution and habitability and a key scientific question. While subducting slabs are known to transport water into the mantle, scientists have long assumed that most hydrous minerals dehydrate at high temperatures, releasing fluids as they descend.

Large-scale melting of the Greenland Ice Sheet is irreversible and happening at a rapid rate, and now a new international study is the first to understand why. A University of Waterloo scientist and a team of international collaborators found that airborne mineral dust and other aerosols are directly connected to how much algae grows on the ice. The algae interfere with albedo, or the reflection of the sun's rays, exacerbating melting. The work is published in the journal Environmental Science & Technology.

A new study using Explainable Artificial Intelligence (XAI) has revealed land-use change—particularly deforestation and unplanned agricultural expansion—is dramatically intensifying heat waves across Africa, with findings that carry direct implications for Australia's warm climate. Although the research focused on Africa, the physical mechanisms behind this amplification are universal.

As high-latitude soils warm, microbes in the soil change how they handle nutrients like nitrogen. Normally, these microbes are nitrogen recyclers, pulling it from the soil and turning it into inorganic forms—like ammonium and nitrates—that plants can absorb. But a new study published in Global Change Biology suggests that with rising temperatures, microbes are changing their strategy. They take up more nitrogen for themselves while reducing the amount they release back into the environment. This change alters the flow of nitrogen through the ecosystem, potentially slowing vegetation growth and affecting the rate at which our planet warms.

These findings come from experiments carried out in subarctic grasslands near Hveragerði, Iceland. In 2008, earthquakes rerouted groundwater in an area that had been warmed by geothermal gradients, creating patches of soil heated between 0.5°C and 40°C above normal temperatures. The event turned the region into a natural laboratory where researchers could study how ecosystems respond to long-term warming under natural conditions.

Earlier research in this location had already shown that in warming soils, microbes become highly active while plants are dormant. As a result, nitrogen-containing compounds released into the soil by the microbes were lost, either by leaching into groundwater or by escaping into the atmosphere as the potent greenhouse gas nitrous oxide.

An abandoned greenhouse near the experimental sites in Iceland serves as a reminder that climate change is having an especially strong effect on high-latitude soils. Credit: Sara Marañón Jiménez

In this work, scientists added nitrogen-15 to the soil, which they could track to determine how much the plants had used up and what they did with it. Researchers found that after the initial nutrient loss, microbes became more conservative in their handling of nitrogen, recycling nitrogen internally rather than absorbing more from the ground. At the same time, microbes stopped releasing ammonium, a nitrogen-rich by-product of their normal metabolism that is usable by plants—the microbial equivalent of urine, said study coauthor Sara Marañón Jiménez, a soil scientist at the Centre for Ecological Research and Forestry Applications in Spain.

Nitrogen Heist

This change in nitrogen cycling has important consequences for the whole ecosystem. On the one hand, it has a positive effect because it prevents further nitrogen loss.

“The study shows that nitrogen is not released as inorganic nitrogen, but it seems to go directly in an organic loop,” said Sara Hallin, a soil microbiologist at the Swedish University of Agricultural Sciences in Uppsala who was not involved in the study. “You could say that it’s a positive aspect, and so it’s more beneficial for the ecosystem if that nitrogen is sort of retained.”

“If microorganisms start immobilizing nitrogen, it could lead to competition between microbes and plants.”

On the other hand, microbes’ nutrient-hoarding behavior might reduce nitrogen availability for plants. “There’s a delicate feedback between plants that take nitrogen, make photosynthesis, and put carbon in the soil as organic matter and microorganisms that take this organic matter, recycle it, and release nitrogen in forms the plants can use,” Marañón Jiménez said. “If microorganisms start immobilizing nitrogen, it could lead to competition between microbes and plants.”

The team is now working on a study to determine what exactly happens to soil at the very early stage of warming, before nutrients have been lost. “This way we hope to recover the first chapters, to see what we’ve been missing,”

To this end, they transplanted bits of normal soils into heated areas to study the process in detail from the very beginning. “Soils exposed to [soil] temperature increases showed the same nutrient loss after 5 years [as] after 10 years,” Marañón Jiménez said, suggesting that most of the nutrient loss occurs early on.

A Greenhouse Time Bomb

Climate models may be underestimating how the loss of nitrogen and carbon from cold soils is contributing to global warming, researchers said. Disruptions to nutrient cycling at these latitudes could represent a previously overlooked source of greenhouse gas emissions.

Arctic soils store massive amounts of carbon, built up over thousands of years from plant material that microbes cannot fully break down. This partially decomposed organic matter accumulates, forming one of the largest carbon reservoirs on Earth. As temperatures rise, scientists expect microbes to become more active, accelerating decomposition and releasing much of this stored carbon into the atmosphere as carbon dioxide.

“As biomass is lost from the microbial mass, that means there’s less storage capacity for carbon and nitrogen in the soil, leading to poorer soils where plants can’t grow as well.”

Researchers had hoped warmer temperatures would allow plants to grow more vigorously, absorbing some of the extra carbon released by Arctic soils.

The new findings call this idea into question. “It’s a chain reaction,” Marañón Jiménez explained. “As biomass is lost from the microbial mass, that means there’s less storage capacity for carbon and nitrogen in the soil, leading to poorer soils where plants can’t grow as well, and plants cannot compensate emissions by absorbing more carbon.”

Studying these geothermally heated soils could yield confusing results, though. “It’s not really the way global warming works,” Hallin said. Global warming includes increases in air temperature, she explained, whereas the plants in the current study had only their root system in a warmer climate, not their aboveground shoot system. “That could potentially cause some effects [the researchers] are not accounting for,” she said.

Finally, the authors of the new study also warn that not all soils have the same response to warming. The Icelandic soils in this study are volcanic and rich in minerals, unlike the organic peat soils that dominate many Arctic regions. Deep peatlands in Scandinavia and northern Russia store vast amounts of carbon and may behave differently, highlighting the need for similar long-term studies across a wider range of Arctic landscapes.

—Javier Barbuzano (@javibar.bsky.social), Science Writer

Citation: Barbuzano, J. (2026), As some soils warm, microbes stockpile essential nutrients, Eos, 107, https://doi.org/10.1029/2026EO260043. Published on 28 January 2026. 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.

Source: GeoHealth

Polluted air causes an estimated 7 million deaths worldwide each year, according to the World Health Organization. Much of the mortality comes from PM2.5, particulate pollution smaller than 2.5 micrometers in diameter that can enter the lungs and bloodstream and cause respiratory and cardiovascular problems. In addition to particles emitted directly into the atmosphere, ammonia (NH3), nitrogen oxides (NOX), and sulfur dioxide (SO2), which are emitted by factories, ships, cars, and power plants, are all precursors that can contribute to the formation of PM2.5. The effects of particulate pollution are not evenly distributed, however.

Oztaner et al. model the consequences of air pollution across the Northern Hemisphere by region, offering a more granular look at where targeted mitigation policies could be the most beneficial. Using the multiphase adjoint model of EPA’s Community Multiscale Air Quality (CMAQ) modeling platform, the authors assessed the benefits of mitigating various pollutants from the perspective of both lives and money saved. Monetary values of air pollution impacts were calculated using a well-established method used by international agencies, although the method introduces ethical concerns because it assigns values to lives partly based on different countries’ per capita gross domestic products (GDP).

Overall, they found that a 10% reduction in all modeled emissions could save 513,700 lives and $1.2 trillion each year in the Northern Hemisphere.

The largest mortality reductions came from China and India, where cutting emissions would save 184,000 and 124,000 lives, respectively, each year. The largest cost savings were found in China, followed by Europe and North America. Health benefits also varied by type of emissions and sector. NH3 causes more issues in China, whereas NOX is relatively more harmful in Europe than in other places. Across the Northern Hemisphere, the agricultural sector contributes most to particulate and precursor pollution, with a 10% reduction in agriculture-related emissions projected to save 95,000 lives and an estimated $290 billion. This is followed by the residential and industrial sectors.

The authors note that caution is warranted when comparing results across similar studies, in part because the link between pollutant concentrations and health outcomes is not always linear and in part because different regions may have different methodologies when accounting for emissions by sector. Also, their study focuses only on PM2.5-related mortality and does not consider other pollutants, such as ozone. Overall, they suggest their work offers a meaningful reference for comparing the effects of different pollutant mitigation strategies in the Northern Hemisphere. (GeoHealth, https://doi.org/10.1029/2025GH001533, 2026)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2026), Which countries are paying the highest price for particulate air pollution?, Eos, 107, https://doi.org/10.1029/2026EO260026. Published on 28 January 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.

Mangrove forests play an important role in the global carbon cycle, particularly within the marine carbon system. Growing along tropical and subtropical coastlines, these salt-tolerant trees are among nature's most efficient "blue carbon" sinks, capturing and burying vast amounts of carbon dioxide that would otherwise warm Earth's atmosphere. Much of this carbon is stored in thick, waterlogged soils, where it can remain locked away for centuries, making mangroves a major contributor to long-term coastal carbon sequestration.

SummaryGeothermal energy production emits significant amounts of hydrogen sulfide (H2S). A strategy to mitigate the emissions is to reinject the H2S into basaltic formations, where it reacts with the rock to form pyrite. Due to the polarization properties of pyrite, the direct current resistivity (DC) and induced polarization (IP) geophysical method (i.e., DCIP) has shown the potential for monitoring H2S mineral storage. However, field applications of DCIP monitoring have been limited by the low spatial coverage of wireline logging and by the ambiguity in interpreting IP signals due to multiple processes that contribute to the polarization response. This study integrates DCIP with field-scale reactive transport modeling, utilizing both synthetic modeling and field investigations, to assess the ability of surface and cross-hole DCIP to monitor H2S mineral storage at the Nesjavellir study site in Iceland. Two surface DCIP datasets were collected at Nesjavellir, with six months of continuous H2S injection between them. Time-lapse inversions, performed using a novel gridding scheme that accounts for electrode misplacement between the two DCIP surveys, recover no significant IP changes beyond data noise. Interpreting these results alongside the reactive transport results finds that pyrite mineralization during the six-month injection period is too small and too deep to be resolved by surface DCIP time-lapse surveying, highlighting the benefit of a joint geophysical-geochemical interpretation approach. Conversely, joint DCIP-reactive transport synthetic modeling shows the potential of cross-hole DCIP for monitoring long-term H2S mineral storage, provided that data noise is low and sufficient H2S is injected. The reactive transport models also provide insight into the mechanisms contributing to the polarization response, demonstrating that pyrite mineralization is the primary contributor to the polarization response, with minimal contribution from other minerals such as smectites and iron oxides. However, existing petrophysical relationships are simplistic, which adds uncertainty to the interpretation of the DCIP signal and the quantification of pyrite mineralization. Additionally, smectite formation has been shown to decrease both the polarization signals and the quality of the IP data due to its electrically conductive properties. At Nesjavellir, a decrease in the DC resistivity from 1925 to 325 Ωm is observed, attributed to the disposal of warm wastewater. This decrease is identified by comparing resistivity data collected in this study to historical vertical electrical sounding data collected prior to geothermal development. Lastly, petrophysical relationships linking DC resistivity, smectite content, and permeability suggest a high basalt fracture permeability of 7.9× 10−12 m2, which agrees with values recovered through flow model calibrations. This result demonstrates the value of geophysical surveying not only for monitoring but also for constraining key parameters in reactive transport simulations.

SummaryMegathrust earthquakes occur at subduction zones and produce many of the largest magnitude earthquakes on record. The ruptures of megathrust earthquakes have classically been thought to nucleate at asperities, zones on the subduction interface of rheological strength which accumulate strain as the plates move. Imaging such asperities would critically inform seismic hazard analyses, to the benefit of millions who live adjacent to major subduction boundaries. We created a 3D shear wave attenuation (QS) tomography of the 2015 MW 8.3 Illapel, Chile, earthquake rupture region by measuring QS using a body wave S/P spectral ratio method along 3,852 ray paths between 708 aftershocks of the 2015 earthquake and a network of 22 broadband seismometers. We then used these measurements in a 3D nonnegative least-squares regression inversion to determine the subsurface QS structure. We identify high QS anomalies on the Nazca – South America subduction interface in the Illapel region which correlate spatially with areas of high frequency seismic radiation and high coseismic slip from the 2015 earthquake, and we interpret these anomalies as asperities. We also observe elongated bands of alternating high and low QS on the plate interface which match the orientation of normal fault fabrics on the surface of the subducting Nazca plate. We interpret the high QS bands as subducted horsts, which are materially strong and prominent, and behave as asperities; low QS bands are subducted grabens full of more attenuating subducted sediments and underplated continental material. These structures guided the rupture of the Illapel earthquake: nucleation occurred in a region of moderate QS (∼400) within a graben, but propagated to two adjacent high QS (> 1000) asperities which were critically stressed to near-failure, one on a horst directly up dip and another on a horst directly down dip. Both of these asperities subsequently failed, causing a cascading rupture which characterized the great earthquake.

SummaryOver the past few decades, the global number of dams has increased substantially. Water impounded behind these dams, resulting in elevated crustal pore pressure and altered stress distribution around reservoirs, could potentially trigger or suppress the failure of nearby faults, leading to transient changes in seismicity. In this study, we analyze 14 years (2006-2019) of spatiotemporal seismicity recorded by a dense local network in the Gotvand area (SW Iran), covering about 5.5 years before and 8.5 years after impoundment. The initial catalog, comprising over 48,000 relocated earthquakes, was reduced to 6,464 background events by adopting a 3D ETAS declustering model with a cutoff magnitude of 1.3. We analyze the spatiotemporal background seismicity pattern in the Gotvand area in comparison with calculated reservoir-related spatiotemporal stress changes relative to the initial stress state before water impoundment, approximating the Gotvand reservoir by 726-point sources covering the reservoir surface. We find that following the initiation of impoundment, the local background seismic activity slightly increased during the impounding, pointing to induced/triggered seismicity. However, most importantly, the impoundment of Gotvand lake has altered the spatial seismicity patterns, leading to a notable reduction in seismic activity in the central area of the reservoir, which is in agreement with the calculated negative Coulomb stress changes in the same area. Using the Coulomb-Rate-and-State seismicity model, we find that the spatiotemporal seismicity response due to the calculated stress changes is consistent with the observations.

SummaryWe present a statistically and computationally efficient spectral-domain maximum-likelihood procedure to solve for the structure of Gaussian spatial random fields within the Matérn covariance hyperclass. For univariate, stationary, and isotropic fields, the three controlling parameters are the process variance, smoothness, and range. The debiased Whittle likelihood maximization explicitly treats discretization and edge effects for finite sampled regions in parameter estimation and uncertainty quantification. As even the ‘best’ parameter estimate may not be ‘good enough’, we provide a test for whether the model specification itself warrants rejection. Our results are practical and relevant for the study of a variety of geophysical fields, and for spatial interpolation, out-of-sample extension, kriging, machine learning, and feature detection of geological data. We present procedural details and high-level results on real-world examples.

SummaryThe Surface Water and Ocean Topography (SWOT) altimeter mission provides high-resolution sea surface heights (SSHs), which can be used to retrieve high-precision and high-resolution marine gravity fields. However, data acquisition from the SWOT satellite’s Ka-band Radar Interferometer (KaRIn) is characterized by a 20-km nadir gap and a seam gap. Interpolation methods were employed to fill the nadir and seam gaps in the SWOT/KaRIn SSHs. The 20-km nadir gaps were interpolated using SWOT/KaRIn SSHs from flanking swaths on both sides. To reduce temporal decorrelation, seam gap interpolation was performed separately for each pass using SWOT/KaRIn SSHs from adjacent passes. The vertical gradient of gravity anomaly (VGGA) model was inverted from the interpolated SWOT/KaRIn SSHs using least-squares collocation and the remove-restore methods. The study region was selected as the Philippine Sea, with SWOT/KaRIn SSHs from cycle-02 serving as the experimental dataset. SWOT/KaRIn SSHs were processed using four schemes: Kriging interpolation, Cubic Spline interpolation (CSI), mean sea surface (MSS) interpolation, and no interpolation. The VGGA models inverted from the respective processed SWOT/KaRIn SSHs are hereafter referred to as Kriging_SWOT_VGGA, CSI_SWOT_VGGA, MSS_SWOT_VGGA, and NO_SWOT_VGGA. The results show that the NO_SWOT_VGGA model exhibits distinct strip artifacts, whereas the interpolated VGGA models eliminate these artifacts. All interpolated VGGA models exhibited superior consistency with the reference model compared to the NO_SWOT_VGGA model. Among them, the Kriging_SWOT_VGGA model achieved optimal consistency. Therefore, this study on interpolation methods for SWOT/KaRIn SSHs provides a novel methodological framework for the recovery of high-precision marine gravity fields from SWOT observations.

Researchers at the University of Kansas have shown the National Severe Storms Laboratory's Warn-on-Forecast System (WoFS) has potential to help weather forecasters issue warnings to emergency managers and the general public well before tornado formation. Their study appears in the peer-reviewed journal Weather and Forecasting.

In its natural state, peatland is one of the largest carbon stores in nature. This is because the soil is so waterlogged and low in oxygen that dead plant material breaks down very slowly. The plants do not fully decompose but instead accumulate over thousands of years, forming thick layers of peat. When a peatland is drained for agricultural use, the water level drops and oxygen enters the peat layer. Microorganisms can then break down the old plant material much faster, releasing carbon that has been stored for many years as the greenhouse gas carbon dioxide (CO₂).

The U.S. Geological Survey (USGS) crowdsourcing platform Did You Feel It? (DYFI) rapidly transforms people's earthquake shaking intensity experiences into detailed maps of damage extent. While the tool's reach is global, language and technology barriers prevent participation in certain areas, according to a USGS and University of Michigan Engineering study published in Seismological Research Letters.

Mass extinctions are extremely catastrophic events on Earth. Throughout Earth's evolutionary history, numerous mass extinctions have occurred, with five major mass extinctions being particularly representative. These extinctions have reshaped the course of life's evolution on Earth. In addition to the five major mass extinctions, many frequent, lower-order extinctions have also taken place on Earth, such as the Norian–Rhaetian Extinction during the Triassic. Regarding the triggering mechanisms of extinctions, the five major events have been relatively well studied. However, the triggering mechanisms of the frequent lower-order extinctions remain unclear.

Narrow bands of ocean covering just over one-third of the world's seas are responsible for absorbing nearly three-quarters of the carbon dioxide that oceans pull from the atmosphere, new research shows. The study, published in Nature Climate Change, reveals ocean fronts play a far larger role in regulating Earth's carbon cycle than previously understood.

Smoke from wildfires may be responsible for 17,000 strokes each year in the United States, new research suggests.

The study, published in European Heart Journal, examined various sources of particulate matter smaller than 2.5 micrometers in diameter (about 30 times smaller than the width of a human hair). Also known as PM2.5, such particles are so small that they can be inhaled and enter the bloodstream, where they have been linked to an array of health effects, including decreased lung function, cardiovascular diseases, and even neurological disorders. But the new study seems to indicate that PM2.5 from wildfires is particularly harmful.

“The longer you’re exposed to smoke, the greater your stroke risk.”

Scientists examined a cohort of about 25 million people over the age of 65 who were covered by Medicare, a federal health insurance program. Between 2007 and 2018, about 2.9 million of those people experienced a stroke. The researchers calculated the average amount of wildfire smoke, as well as nonsmoke PM2.5, that each study participant was exposed to over the course of each year on the basis of participants’ zip codes.

After 1, 2, or 3 years of exposure to nonsmoke PM2.5, the participants’ risk of stroke didn’t change much.

“But for smoke, this picture is very different,” said Yang Liu, a health and environmental scientist at Emory University and corresponding author of the paper. “It’s like you are seeing some kind of a dose-response effect: The longer you’re exposed to smoke, the greater your stroke risk.”

More specifically, the study found that an increase of 1 microgram per cubic meter in the average concentration of wildfire smoke was associated with a 1.3% increase in stroke risk. Researchers found that Medicaid-eligible individuals (those who qualify for the program have limited income and resources) were especially vulnerable to the effects of wildfire smoke.

Unique Harms of Wildfire Smoke

The researchers input air quality data from several sources, including satellites, ground-based air monitors, and low-cost sensors such as PurpleAir devices, into a machine learning framework. The framework was used to estimate the daily wildfire smoke PM2.5 and nonsmoke PM2.5 concentrations across the contiguous United States at a 1-kilometer resolution. The team then used this information to calculate the average exposure rates within each zip code over 1, 2, and 3 years.

Their model and subsequent analyses of the findings were also designed to control for other factors that could affect stroke risk, including meteorology (extreme heat can increase stroke risk), access to care, Medicaid eligibility, and substance abuse disorders.

Jennifer Stowell, a geohealth scientist at the University of Maryland, said this was an “important” study.

“I really like where this paper has gone because they’ve characterized exposure slightly differently,” she said. “Rather than looking at more acute exposure, they looked at up to 3 years of exposure prior to a stroke. Also, other studies, for the most part, rely on emergency department data. So the fact that this is data in addition to that, from doctors’ offices and all sorts of things, is a big plus.”

The study did not establish the reason for the link between wildfire smoke exposure and stroke risk, but previous studies have suggested that inhaling pollutants can cause oxidative stress that affects the function of the endothelial cells (those lining the blood and lymphatic vessels) and of the cardiovascular system as a whole.

The study’s findings are also in line with previous research: A 2021 study suggested that PM2.5 from wildfires is up to 10 times more harmful than PM2.5 from other sources, such as ambient pollution.

“It all comes down to what [materials] wildfires are burning,” Stowell said. “There is a lot of organic matter, chemicals, and particles that we don’t normally see in air pollution from traffic or from industry that can be emitted during a fire. This is especially true if that fire burns any sort of man-made structures. Then, you start getting some highly toxic, synthetic emissions that we don’t normally breathe.”

Only a Small Part of the Picture

In a world where wildfires are growing both more frequent and more severe, Liu said he hopes a study like this will help guide future research, noting the importance of a large-scale epidemiological study to complement lab-based research.

“Policymakers can look at the disease burden numbers and say, ‘Wow, it may be worthwhile to spend more money on firefighting, or forest management, because it’s a huge disease burden.’”

“I think its real burden is going to be much, much larger than what we show in this paper.”

Liu said he wasn’t at all surprised by his team’s findings because stroke is only one part of the overall picture of how smoke affects overall health.

“I think its real burden is going to be much, much larger than what we show in this paper,” Liu said. In fact, he noted that the study focuses only on the fee-for-service Medicare population and doesn’t account for the more than 40% of the Medicare population enrolled in private insurance.

“So even for the overall Medicare population, or just the elderly population in the U.S., we are underreporting the burden, maybe by half,” he said.

—Emily Gardner (@emfurd.bsky.social), Associate Editor

Citation: Gardner, E. (2026), Wildfire smoke linked to 17,000 strokes annually in the United States, Eos, 107, https://doi.org/10.1029/2026EO260042. Published on 27 January 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.