Feed aggregator

Publication date: 15 January 2026

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

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

Using a new method to track groundwater levels and greenhouse gas emissions, researchers uncover the climate impact of Southeast Asia's peatlands. In Indonesia, Malaysia, and other parts of Southeast Asia, vast areas spanning up to 300,000 square kilometers have emerged over thousands of years as plants grow and thrive in dense tropical peat swamp forests, then die and slowly decompose in waterlogged, low-oxygen conditions.

When representatives of 197 countries ratified the Montreal Protocol to phase out ozone-depleting substances in 1987, they probably didn’t anticipate creating a new method for estimating the age of groundwater.

But the Montreal Protocol paved the way for a chemical called trifluoroacetic acid, or TFA, to become widespread in the atmosphere, and therefore in rainwater. Because the concentration of TFA has increased steadily since 1987, it’s a helpful tool for gaining a rough idea of how recently an aquifer has been recharged—which is what is meant by “groundwater age.”

Using TFA as a quick and easy tracer is one of several research techniques that rely on the mass amounts of anthropogenic material that enter the environment every moment of every day. Scientists are using pollution to study processes both small-scale and worldwide, from the history of a single bird’s nest to the history of humans on this planet.

Novel Tracers

TFA is one of thousands of per- and polyfluoroalkyl substances (PFAS), which are also known as “forever chemicals” because they take thousands of years to degrade. Fortunately, TFA seems to be much less toxic than the long-chain PFAS, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), that have been associated with human health problems.

TFA’s omnipresence is a side effect of the move from using ozone-depleting chlorofluorocarbons (CFCs) in refrigerants. The alternative refrigerants, originally thought to be less harmful than CFCs, have consequences of their own, however, making this a case of what scientists have called “a regrettable substitute.”

Cyclists ride in front of a bus on a rainy evening in Copenhagen, Denmark, where scientists have used the concentration of trifluoroacetic acid (TFA) in rain to estimate the age of groundwater. Credit: Kristoffer Trolle/Wikimedia Commons, CC BY 2.0

When modern refrigerants evaporate into the atmosphere, they break down into TFA, which then falls to the ground in the rain, explained environmental geochemist Christian Nyrop Albers from the Geological Survey of Denmark and Greenland.

Groundwater becomes drinking water, so part of Albers’s job is to screen groundwater for pollutants. But to convince politicians they need to regulate a pollutant, he and his colleagues need to show that the substance is entering groundwater because of how it’s used today, not in decades past. So they need to know how old the groundwater is.

More sophisticated methods “are not always very easy to use, or they are very expensive or time-consuming.”

“There are many sophisticated methods for that, but they are not always very easy to use, or they are very expensive or time-consuming,” Albers said. The gold standard is to measure the decay of a substance called tritium into helium, but only a few labs in the world have the capacity to do the test, and the water sample must be stored for 6 months to see the decay.

Measuring TFA is not as precise as measuring tritium decay, and those using the technique have to be cognizant of any farms in the area, because agricultural chemicals can also release TFA into the groundwater and affect results. But measuring TFA is fast and easy, so “we use it on a regular basis now,” Albers said. He and his colleagues recently published the method, and a research group in Germany has begun using it, too.

In general, PFAS in the environment are the “subject of huge amounts of discussion,” said environmental radiochemist Andy Cundy from the University of Southampton, who was not involved in developing the method. “As the measurement of PFAS becomes more routine, I think we will see more and more people using PFAS as tracers,” he added.

Plastic Cuts Both Ways Among the nests Auke-Florian Hiemstra analyzed was a common coot’s nest containing plastic dating back to the 1990s. Credit: Auke-Florian Hiemstra

More than 460 million metric tons of plastic are produced each year, with that number growing all the time. When it’s used as food packaging, plastic often comes with an expiration date stamped on it. Auke-Florian Hiemstra of the Naturalis Biodiversity Center in Leiden, Netherlands, is a nidologist, or a scientist who studies birds’ nests. He used those expiration dates to trace the history of birds’ nests found along the canals in Amsterdam. In the past, carbon-14 dating has been applied to some very old nests, but using plastic proved to be a far easier process.

Scientists used trash to date the construction of birds’ nests in Amsterdam. Click image for larger version. Credit: Auke-Florian Hiemstra

“This one bird nest that we found turned out to be like a history book,” Hiemstra said. The trash within it ranged from face masks from the COVID-19 pandemic to a candy bar wrapper advertising the 1994 FIFA World Cup. Of course, a piece of plastic’s expiration date doesn’t correspond exactly to the date when a bird incorporated it into its nest, but finding several pieces from the same time frame is suggestive. To increase confidence in the method, the researchers integrated their findings with the archives of Google Street View, which showed the presence of the nest at various points in time.

But even as plastic opens opportunities to estimate the ages of some natural materials, it may make it harder to tell the ages of others. That’s because plastic is derived from long-dead plants and animals that have negligible amounts of the carbon-14 isotope that’s used for carbon dating. Plastic carbon may dilute natural carbon and make materials appear older than they are.

This could be problematic for the study of ocean processes. One way of measuring how long it’s been since water was at the surface relies on carbon-14 dating. If 1% of the carbon in a sample of water is from microplastics—a conservative estimate given that up to 5% of ocean carbon is from plastic in some samples—then that would make the sample appear 64 years older than it actually is, calculated environmental oceanographer Shiye Zhao from the Japan Agency for Marine-Earth Science and Technology.

Ocean circulation proceeds over thousands of years, so adding 64 years doesn’t change the overall picture by very much. But the amount of plastic is always increasing, so “think about this in a future scenario,” Zhao said. Especially in plastic hot spots, the material could obscure the study of ocean circulation substantially.

“That could be an issue as more microplastics enter the ocean,” said Cundy.

The Anthropocene

Anthropogenic pollution can help scientists understand how nature is responding to other aspects of human influence.

We’re living in a period that’s colloquially called the Anthropocene because markers of human activity are obvious in environmental records worldwide. Although no formal date has been agreed upon, scientists have proposed a range of dates for when the Anthropocene began. One definition suggests that the period began in the mid-20th century and is marked by many human-made substances, such as plastic, that are evident in geological strata, including ice and sediment cores. But one of the most ubiquitous and reliable candidate markers for the start of the Anthropocene is plutonium-239. Atomic bomb tests conducted in the 1940s and 1950s were the main sources of plutonium-239, which went flying into the atmosphere and around the globe, depositing a layer across Earth and “labeling the entire planet,” said Cundy.

Having a marker for when anthropogenic activities began to affect the geological record is a powerful research tool.

Having a marker for when anthropogenic activities began to affect the geological record is a powerful research tool because it provides a benchmark against which scientists can measure how nature has responded since, said environmental geochemist Agnieszka Gałuszka from Jan Kochanowski University of Kielce, in Poland.

In a study of pollen in paleoecological records from across North America, for example, scientists looked at how the diversity of plant species has changed since the mid-20th century and compared that with previous time periods. They found that rates of species appearing and disappearing have been higher at any other time since the end of the last ice age, about 13,000 years ago. That’s probably because of land use changes, as well as of introduction of pests and invasive species to the continent, all driven by humans.

Likewise, in a study of peatlands in the Izery Mountains of Europe, researchers investigated how coal burning has affected microorganisms since the mid-1960s. By analyzing microbial communities, scientists discovered that amoebae picked up titanium, aluminum, and chromium from inorganic coal residue and incorporated these elements into their shells. “It was quite shocking news to all of us,” Gałuszka said.

Identifying pollutants as markers of the plausible start of the Anthropocene has led scientists to ask, “What has been the change over time?” said Cundy. “And, importantly, what have been the causes of that change over time? Is it human induced, or is it natural?”

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

Citation: Sidik, S. M. (2026), Pollution is rampant. We might as well make use of it., Eos, 107, https://doi.org/10.1029/2026EO260039. Published on 30 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: AGU Advances

Earth’s ocean absorbs carbon dioxide from the atmosphere, helping to temper the impact of climate change but increasing ocean acidity. However, calcium carbonate minerals found in the seabed act as a natural antacid: Higher acidity causes calcium carbonate to dissolve and generate carbonate molecules that can neutralize the acid.

For many years, researchers have thought of this carbonate dissolution buffer mainly as a very slow process because most ocean carbonates lie in deep-ocean sediments. There, the effects of their dissolution won’t reach the atmosphere for hundreds or thousands of years—long after many effects of acidification are already felt by ecosystems.

However, calcium carbonate also exists in more than 60% of the seabed of the shallower waters of continental shelves. New research by van de Velde et al. suggests that shelf carbonate dissolution may play a previously underappreciated climate feedback role on much faster timescales.

To explore the potential importance of shallow carbonate dissolution, the researchers analyzed high-precision ocean carbonate chemistry observations collected over 25 years in continental shelf waters off the southeastern coast of New Zealand.

They found that in the study area, calcium carbonate buffering has occurred in shallow shelf waters for at least the past 25 years and that this climate feedback process operates on annual to decadal timescales—orders of magnitude faster than in the deep ocean. Additional biogeochemical modeling suggested that this continental shelf carbonate dissolution is driven by an increase in dissolved carbon dioxide resulting from anthropogenic carbon dioxide emissions.

Similar dissolution feedback may occur in continental shelf waters around the world, in which case, shelf carbonate dissolution may have been accelerating globally since the 1800s. Furthermore, the researchers calculated that this process could account for up to 10% of the current discrepancy between state-of-the-art model predictions of ocean carbon dioxide uptake and real-world measurements.

Further research will be needed to explore the global role of shelf carbonate dissolution and how it should be incorporated into climate models. Such knowledge could have key implications for proposed efforts to combat climate change by deliberately boosting ocean alkalinity, the authors say. (AGU Advances, https://doi.org/10.1029/2025AV001865, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2026), Our ocean’s “natural antacids” act faster than we thought, Eos, 107, https://doi.org/10.1029/2026EO260013. Published on 30 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.

Australia has always had heat waves. But this week's heat wave in southeastern Australia is something else. Temperatures in some inland towns in South Australia, New South Wales and Victoria were up to 20°C above average for the time of year, which meteorologists described as "incredibly abnormal." Victoria's heat record toppled after Walpeup and Hopetoun hit 48.9°C. The heat is set to continue until Saturday in some areas.

This week, Victoria recorded its hottest day in nearly six years. On Jan. 27, the northwest towns of Walpeup and Hopetoun reached 48.9°C, and the temperature in parts of Melbourne soared over 45°C. Towns in South Australia also broke heat records.

Far from simply a source of unstructured online content, disaster management in the digital age can be supported by careful analysis of online social-media data, suggests a paper published in Natural Hazards and Earth System Sciences (NHESS) titled "Social Media for Managing Disasters Triggered by Natural Hazards: A Critical Review of Data Collection Strategies and Actionable Insights."

SummaryGlobal Navigation Satellite System (GNSS) plays a fundamental role in monitoring time-dependent ground displacement. However, GNSS daily position time series can often contain significant outliers, reaching up to several centimeters. These are likely of non-tectonic origin, and, if not properly accounted for, they can significantly impact the accuracy and dependability of the estimation of key parameters for geophysical analyses, such as long-term velocities and transient deformations. Characterizing these outliers can provide information about their possible sources and help us implementing mitigation strategies. Asymmetric outliers, i.e., those characterized by a primary direction, therefore occurring on one side of the mean time series, are of particular interest since they could point to the presence of recurring or repeatable sources of error. Their key features and potential causes are, however, still not fully analyzed and understood. We analyze asymmetric outliers in thousands of GNSS time series across three regions – Central-Southern Italy, New Zealand, and the Western U.S. – using data from multiple processing centers, and we reveal some persistent features among all datasets. Tens of the analyzed sites exhibit hundreds of large outliers (10-50 mm), far exceeding typical position uncertainties (∼1-6 mm). Remarkably, the outliers are numerous in the horizontal component, and tend to occur near mountainous regions, with preferred direction roughly orthogonal to the local topography. The results consistency across different datasets and instrumental features suggest a physical origin for these outliers rather than a specific processing approach or instrumental configuration. Further analyses at local scales align with previous studies linking skewed position errors to uncorrected tropospheric delays driven by the coupling between atmospheric conditions and local terrain (e.g., trapped lee waves). However, other factors – such as multipath, snow accumulation on GNSS antennas or obstructed sky visibility – could also contribute to the observed asymmetric outliers. We explore mitigation strategies at both processing and post-processing stages, but further analyses and more sophisticated approaches, such as high-resolution tropospheric modeling, are needed to better understand the involved processes and achieve meaningful improvements.

SummaryThe Gravity Recovery and Climate Experiment (GRACE) and its Follow-On mission provide essential observations of Earth’s surface mass redistribution. However, inherent north-south striping noise in the GRACE spherical harmonic (SH) products limits their application at sub-basin scales. To address this, we introduce a novel spatial domain decorrelation filter, the Physical-Informed Spatial Pattern (PISP) filter, which leverages the structured physical characteristics of the noise for its precise identification and removal. Comprehensive numerical experiments validated that PISP effectively eliminates striping noise globally and yields a consistent noise background across latitudes, with noise reduced to a uniform level in more than 90% of the months examined and with stable performance under strong-noise conditions. In a case study of water storage variations in Lake Victoria, PISP preserves the primary signal amplitude and reduces the root-mean-square error relative to reference data to 5.84 cm after spatial smoothing, outperforming the 6.81 cm achieved by the MVMDS + DDK6. Furthermore, for three earthquakes with magnitudes exceeding 8.8, PISP effectively removes striping noise using regional masking, successfully recovering the co-seismic signal morphology. By further verifying the method’s stability across various noise scenarios, the results demonstrate PISP’s potential for future global research integrating multi-satellite gravity data.

SummarySlowslip events (SSEs) modulate the earthquake cycle in subduction zones, yet understanding their physics remains challenging due to sparse observations and high computational cost of physicsbased simulations. We present a scientific machine-learning approach using a data-driven reduced-order modelling (ROM) framework to efficiently simulate the SSE cycle governed by rate-and-state friction in a Cascadia-like 2D subduction setting. Our approach projects fault slip, sliprate, and state-variable trajectories onto a splinebased latent space, which is subsequently emulated using properorthogonal decomposition and radialbasisfunction interpolation. Achieving a speedup of ∼360, 000 × compared to volumetric simulations, the ROMs enable comprehensive parameter exploration and Bayesian Markov chain Monte Carlo (MCMC) inversion. By smoothly interpolating between the physics-based simulations, the ROMs reveal complex dependencies that might be overlooked with coarser parameter space sampling. Our analysis reveals complex, non-linear dependencies of SSE characteristics on the width and magnitude of the deep, low-effective-normal-stress region while holding frictional parameters constant. We show that, to first order, the recurrence time of SSEs is linearly dependent on the normalized fault width, defined as the SSE zone width divided by the characteristic nucleation length, in agreement with previous work. However, at second order, the recurrence interval can change more rapidly with small variations in the SSE zone width. We identify a region of steep, non-linear dependence of the recurrence interval on the normalized fault width, which we attribute to the extent of the velocity-weakening portion of the subduction interface that produces SSEs. Our MCMC inversion constrained by Northern Cascadia SSEs observations indicates near-lithostatic pore fluid pressure (99.6 ± 0.17% lithostatic) and positions the upper frictional transition zone at 30.4 ± 2.8 km depth, consistent with geophysical observations. The inversion resolves the deep SSE-portion of the slab spanning 45 ± 16 km with low effective normal stress of 3.8 ± 1.4 MPa. We discuss how varying the fault frictional parameters affects the MCMC-inverted parameter values. This framework provides a new tool for advancing the physics-based understanding of SSEs and subduction zone faulting mechanics. By systematically linking megathrust properties such as fluid pressure and fault strength to rate-and-state friction governed slow slip cycle characteristics, such as recurrence interval, our approach helps to constrain the first and second-order physics-based controls and the uncertainties of how subduction zones slip.

SummaryDuring the last glacial period, the Black Sea developed oxic bottom waters that generally preserved detrital titano-/magnetite, yet greigite (Fe₃S₄) occurs sporadically within nodules in these otherwise oxic sediments. To clarify their origin and significance, we combined rock magnetism, X-ray diffraction, and scanning electron microscopy with energy-dispersive X-ray spectroscopy on nodules from core MSM33-55-1 and screened fifteen nearby cores using the ratio of saturation isothermal remanent magnetization to low-field magnetic susceptibility (SIRM/κLF). SIRM/κLF thresholds were applied to classify samples as greigite-bearing and greigite-free, then the greigite-bearing sample proportion was calculated in 0.3-kyr bins from 70 to 20 ka. The nodules have S-rich interiors (elemental sulphur plus greigite) coated by Fe-hydroxide rims (goethite), indicating formation in localized sulphidic microenvironments embedded in otherwise oxic sediment. Palaeomagnetic comparisons indicate that greigite-bearing samples track greigite-free (detrital titano-/magnetite) records for relative palaeointensity (RPI) and inclination (zero lag for inclination; ∼0.5 kyr lag for RPI), which implies that greigite formed shortly after deposition and acquired an early-diagenetic chemical remanent magnetization near-synchronous with a detrital post-depositional remanent magnetization. Greigite-bearing sample proportion increases during interstadials with modest but significant positive correlations with total organic carbon (TOC) content (and TOC/κLF) and a negative correlation with κLF, consistent with enhanced organic-matter supply relative to detrital input promoting sulphidic microenvironments. Together, these results demonstrate that greigite-bearing nodules can be incorporated into palaeomagnetic reconstructions when carefully screened, and that they serve as markers of micro-scale sulphidisation coupled to conditions that favour organic-carbon retention in glacial Black Sea sediments.

Researchers at Concordia have developed a new method of measuring the amount of usable water stored in snowpacks. The comprehensive technique, known as snow water availability (SWA), uses satellite data and climate reanalysis techniques to calculate snow depth, snow density, and snow cover across a wide swath of Canada and Alaska.

Should growing glacial lakes be used for energy production and water supply—or remain protected as ecologically valuable systems? A research team from the University of Potsdam, together with partners from the University of Leeds, has recorded the distribution and volume of glacial lakes worldwide. Their findings allow various usage scenarios to be derived, particularly in areas where the largest glaciers still exist today. Their article has been published in Nature Water.

A new study led by climatologists at the University at Albany has found that extreme heat waves across the Caribbean are becoming significantly more frequent, longer and severe. This study examined extreme summer heat waves in the Caribbean over the last five decades, focusing on their causes and how they have changed over time.

Forecasting volcanic eruptions in time to alert authorities and populations remains a major global challenge. In a study published in Nature Communications, researchers and engineers from the Institut de Physique du Globe de Paris (IPGP) and the GFZ Helmholtz Centre for Geosciences present a new detection method, called "Jerk," using a single broadband seismometer. It is capable of identifying, in real time, very early precursor signals of volcanic eruptions generated by subtle ground movements associated with magma intrusions.

For decades, families in communities around Johannesburg have been living close to huge gold mining waste dumps. For many residents, the dust that is released there is just part of everyday life—but it can contain natural uranium compounds that come to the surface with the mined rock. A new study in the journal Environmental Geochemistry and Health reveals how this exposure is reflected in children's hair.

People living on the low-lying shores of the Bristol Channel and Severn estuary began their day like any other on January 30, 1607. The weather was calm. The sky was bright.

The King's Trough Complex is a several-hundred-kilometer-long, canyon-like system of trenches on the North Atlantic seafloor. Its formation was long thought to be the result of simple stretching of the oceanic crust. An international research team led by the GEOMAR Helmholtz Center for Ocean Research Kiel has now shown that the so-called "Grand Canyon of the Atlantic" was formed about 37 to 24 million years ago through the interplay of a temporarily existing plate boundary and an early branch of the Azores mantle plume. Their findings have been published in the journal Geochemistry, Geophysics, Geosystems.

To reduce air pollution associated with ocean transport, the International Maritime Organization tightened restrictions on sulfur content in ship fuel, resulting in an 80% reduction in emissions by 2020. That shift created an inadvertent real-world experiment in how man-made aerosols influence cloud formation over the ocean.

When most of us look out at the ocean, we see a mostly flat blue surface stretching to the horizon. It's easy to imagine the sea beneath as calm and largely static—a massive, still abyss far removed from everyday experience.