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Mangrove forests, once considered one of the world's most threatened coastal ecosystems, are showing signs of recovery worldwide, according to new research from Tulane University that finds decades of losses largely offset by regrowth and expansion.

Ozone pollution has worsened in much of the continental United States over the past decade, fueled by wildfires and the long-distance transport of unhealthy air, according to a new study titled "Fires reverse progress toward ozone air quality standards in the U.S.," led by University of Iowa researchers and published in the journal Science.

Arctic communities are increasingly exposed to dangerous weather events due to climate change and rely on accurate weather forecasts. However, conditions in the lower atmosphere remain poorly observed in the Arctic because monitoring systems are expensive and difficult to deploy.

For the first time, mighty ocean waves generated in the Southern Ocean have been accurately measured all the way to the tiny ripples they form on the shores of Alaska. Professor Ian Young, from the University of Melbourne's Department of Infrastructure Engineering, is lead author on a landmark study that analyzed data from 300 drifting ocean buoys to gain a detailed understanding of how storms in Antarctica drive waves all around the globe.

Deep below the Tyrrhenian Sea offshore Italy, scientists drilled into what they thought would be dark mantle rock—and found pieces of granite that seemingly had no business being there. Those unexpected intrusions turned out to offer a rare glimpse of how a massive fault rapidly pulled deep Earth rocks toward the surface during the opening of a young ocean basin.

Earth is divided into two halves: the Northern and Southern Hemispheres. Both reflect equal amounts of sunlight (albedo) even though they have different landmasses and weather patterns, especially cloud distribution. Why this is so is an ongoing mystery waiting to be solved.

You may have heard the rumors of a "monster El Niño." It's not the first time we've heard forecasts like this in Australia, but this time, they aren't coming out of nowhere. Early signs in the Pacific have been building for months and forecasts now point to a high likelihood of a moderate to strong El Niño developing in 2026.

After centuries of overharvesting and environmental degradation reduced the world’s oyster reefs by 85%, restoration is bringing the conglomerations of thick-shelled mollusks back to coastal waters. And their return may have more benefits than scientists realized, new research suggests.

“Oysters build the foundation of an entire ecosystem.”

Oysters were initially restored to boost depleted fisheries, according to Rachel Smith, a marine ecologist at the University of California, Santa Barbara. As oysters cement their shells together into reefs, they create habitats for myriad species, including fish. “Oysters build the foundation of an entire ecosystem,” Smith said.

These days, oyster reefs are restored for reasons extending beyond ecology, including to rid coastal water of excess nutrients such as nitrogen. This pollutant enters coastal waters when wastewater, sewage, and fertilizer wash into the sea.

Past studies of nitrogen removed by oyster reefs largely looked at denitrification, a process in which microbes transform organic nitrogen in dead oysters and their excrement into inert gas. If organic nitrogen evades these microbes, it can be buried in reefs, but measurements of this mechanism are few.

Researchers collected cores from 20 oyster reefs in coastal North Carolina. Credit: Antonio Rodriguez/Institute of Marine Sciences, UNC-Chapel Hill

“[Burial] is definitely much less explored,” said Smith.

A study published in PLoS One looked beyond denitrification and found significant amounts of nitrogen become sequestered within oyster reefs as they grow, offering evidence that restored oyster reefs actually remove far more nitrogen than we thought.

Before she started this research, Anne Margaret Smiley, lead author of the new paper and a biogeochemist at the University of North Carolina (UNC) at Chapel Hill, suspected that the amount of nitrogen buried in oyster reefs would be small because organisms at the surface transform so much of it, leaving little left to bury. She was pleasantly surprised by the results.

“We’ve been looking at denitrification all this time, and now we found out that [oysters themselves] are really good at doing this too,” she said. “What an amazing thing to know.”

In Search of Buried Nitrogen

To explore how nitrogen is buried over time, scientists turned to 20 oyster reefs in the Rachel Carson National Estuarine Research Reserve near Beaufort, N.C., that were restored nearly 3 decades ago by UNC scientists.

Using a jackhammer and metal pipe, they extracted cores from the oyster reefs in 2011. About 10 centimeters in diameter, the cores sampled the full thickness of each reef, which ranged from 10 to 55 centimeters. Shortly after they were collected, the cores were sectioned off into 5-centimeter increments, sealed, and stored in a walk-in freezer. In the years since, the samples have proved useful for studying oyster reef growth during sea level rise and how much carbon the reefs sequester and in other areas of research. Recently, Smiley measured the nitrogen levels in each of these 5-centimeter sections.

Below the top 10 centimeters or so, where microbes break down organic matter, nitrogen levels increased. Looking at all samples, Smiley found that on average, a square meter of reef buried more than 6 grams of nitrogen each year, which is similar to the rate of nitrogen transformed by denitrification at oyster reefs.

“The more they can build up and out, the more [nitrogen] they can bury underneath.”

However, there was a large range in the amount of nitrogen buried, between 1 and 15 grams of nitrogen per square meter. The variability, the researchers found, was related to where the different oyster reefs grew.

For oyster reefs in sand flats, those in intertidal areas (between high and low tide on a shore) buried more than twice as much nitrogen as subtidal reefs, on average. Intertidal reefs grow faster and so bury more nitrogen. “The more they can build up and out, the more [nitrogen] they can bury underneath,” said Smiley.

But intertidal reefs that fringed the edge of salt marshes buried less nitrogen than other intertidal reefs. “They’re not able to grow as quickly,” she said, speculating that sediment from the neighboring marshes may slow reef growth.

Put Your Money Where Your Mollusk Is Intertidal oyster reefs, like this one in coastal North Carolina, are exposed above water at low tide. Credit: Johanna Rosman/Institute of Marine Sciences, UNC-Chapel Hill

North Carolina’s Department of Environmental Quality places the economic value of each kilogram of nitrogen removed from the environment at $26.39 (in 2024 dollars, which is about $28.50 in 2026). Using this figure, Smiley and her colleagues calculated that nitrogen removed from coastal waters and buried each year by a hectare of oyster reef has a value of $1,700 on average. This finding increases previous estimates of the value of oysters’ nitrogen removal services by 25% to 42%.

“A really valuable part of the study is not just taking those measurements, but then also translating that into valuation,” said Smith, who was not involved with the new study. The value of nitrogen burial can be added to oyster reef ecosystem services—the monetary value of benefits that humans gain from oyster reefs, such as clean water, food, and flood control. “[Buried nitrogen] is definitely an ecosystem service that I think is underappreciated,” she said.

Looking more broadly at the county that is home to the Rachel Carson Reserve, Smiley and her colleagues found that all the oyster reefs countywide bury about 120,000 kilograms of nitrogen each year—more than $3 million of value in the county’s shallow sounds and bays.

—Lisa S. Gardiner (@lisasgardiner.bsky.social), Science Writer

Citation: Gardiner, L. S. (2026), Oysters clean up more nitrogen pollution than we thought, Eos, 107, https://doi.org/10.1029/2026EO260182. Published on 4 June 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.

Editors’ Vox is a blog from AGU’s Publications Department.

Mesoscale and submesoscale ocean processes influence ocean circulation, air-sea fluxes, ecosystem variability, and transport of materials. A new article in Reviews of Geophysics examines how these fine-scale processes shape the Indian Ocean, an ocean basin with unique monsoon behavior and a disproportionate impact on global climate. Here, we asked the authors to explain what mesoscale and submesoscale processes are, the techniques and challenges of observing and modeling fine-scale processes, and how biogeochemical cycles and climate change interact with these processes.

In simple terms, what are mesoscale and submesoscale processes?

Mesoscale processes pertain to oceanic features such as eddies and fronts, which
typically span a range of approximately 10 to 100 kilometers and can persist from
weeks to months. Submesoscale processes are of an even smaller scale, ranging
between approximately 100 meters and 10 kilometers, and evolve rapidly within a time frame of hours to days. These encompass sharp fronts, filaments, and small vortices.

Mesoscale processes account for more than 80% of the total kinetic energy. Submesoscale motions are of particular significance as they generate robust vertical movements that establish a connection between the surface ocean and deeper layers. As elaborated in our review, mesoscale and submesoscale processes function as a crucial link between large-scale ocean circulation and small-scale turbulence, facilitating the transfer of energy across different scales and regulating the distribution of heat, salt, and nutrients throughout the ocean.

Why is it important to understand how fine-scale processes operate in the Indian Ocean?

The Indian Ocean has a disproportionate influence on global climate.

The Indian Ocean has a disproportionate influence on global climate. It absorbs over a quarter of the ocean’s net heat gain and directly affects the environment and food security of nearly one-third of the world’s population. Unlike other ocean basins, the Indian Ocean is uniquely shaped by seasonally reversing monsoon winds and is strongly coupled with climate modes like the Indian Ocean Dipole and the Madden- Julian Oscillation. Mesoscale and submesoscale variability in this region modulates biogeochemical cycles, air-sea fluxes, and even large-scale energy balance. As our review highlights, understanding these fine-scale dynamics is essential for improving predictions of monsoon rainfall, tropical cyclone behavior, and long-term climate change.

How do scientists study mesoscale and submesoscale ocean processes?

Scientists employ a combination of field measurements, satellite observations, and numerical models, all of which were summarized in our review. In-situ observations serve as the foundation for mesoscale and submesoscale processes in the ocean. They encompass research cruises, moored arrays such as the RAMA network, Argo profiling floats, and autonomous platforms. The in-situ observations capture the three-dimensional structures and multiple variables during mesoscale and submesoscale processes.

Satellite altimetry has long been the principal tool for observing mesoscale eddies. However, the newly launched Surface Water and Ocean Topography (SWOT) mission is revolutionary, as it offers sea surface height measurements at an unprecedented resolution, enabling the direct observation of submesoscale features for the first time.

High-resolution regional models with grid spacings of a few kilometers or less enable researchers to simulate these processes and test dynamical theories under controlled conditions.

What are some of the challenges in observing and modeling these processes?

In our review paper, we tackled the challenges in observations by adhering to four principles, namely high-resolution (more observations in a relatively small region), synchrony (observations conducted at the same time), persistence (observations for a long time), and interdisciplinary (observations of multiple ocean properties). These principles are anticipated to offer valuable guidance for future observational endeavors to surmount the corresponding challenges.

Modeling also poses difficulties. Even state-of-the-art climate models are unable to explicitly resolve submesoscale processes. Consequently, their effects have to be approximated via parameterizations. The development of accurate parameterizations continues to be an active area of research. Moreover, as the model resolution improves, the widely employed hydrostatic approximation may lose its validity, necessitating more intricate non-hydrostatic formulations. Data assimilation for such rapidly evolving features presents a particularly arduous challenge.

How do fine-scale processes interact with biogeochemical cycles in the Indian Ocean?

Mesoscale and submesoscale motions exert a strong regulatory influence on biogeochemical cycling.

Mesoscale and submesoscale motions exert a strong regulatory influence on biogeochemical cycling through the control of nutrient supply to the sunlit upper ocean. Cyclonic eddies elevate nutrient-rich deep waters into the euphotic zone, thereby promoting phytoplankton blooms. In contrast, anticyclonic eddies typically suppress surface productivity by deepening the mixed layer.

In the Arabian Sea, eddies and filaments can contribute up to 70% of the nutrients that support the monsoon-driven biological bloom. These fine-scale dynamics also have an impact on carbon dioxide exchange; mesoscale variability accounts for approximately 40% of the CO₂ flux variability in the western Arabian Sea. Moreover, eddies modulate oxygen minimum zones in the Arabian Sea and Bay of Bengal, where low oxygen levels have a profound effect on marine ecosystems.

How is climate change expected to influence these fine-scale processes in the Indian Ocean?

With the continuous progression of climate change, alterations in upper-ocean stratification, propelled by warming and modified freshwater inputs, are anticipated to transform the conditions giving rise to fine-scale instabilities. High-resolution climate model simulations suggest that in a warming global scenario, the eddy-active region associated with the Agulhas Current system may shift westward and poleward. This shift is correlated with the intensification of Agulhas leakage, which refers to the transport of warm Indian Ocean water into the Atlantic. These changes could exert far-reaching effects on global ocean circulation.

Warming is augmenting the frequency and intensity of marine heatwaves in the Indian Ocean.

Moreover, warming is augmenting the frequency and intensity of marine heatwaves in the Indian Ocean. These heatwaves disrupt vertical mixing and nutrient supply, thereby having cascading impacts on biological productivity. Nevertheless, substantial uncertainties persist in quantifying these long-term responses.

In general, there are two-way interactions between climate change and fine-scale processes. Alterations in one component will induce changes in the other, and the former will be subject to feedback from the latter.

What are the remaining questions or knowledge gaps where additional research is needed?

Our review reveals several key priorities. In the short term, specialized multi-scale observational campaigns are acutely required, especially in regions with insufficient sampling, to capture the three-dimensional structure and rapid evolution of submesoscale features. Additionally, a more in-depth understanding is needed regarding how eddies interact with barrier layers—regions characterized by strong salinity stratification that are unique to the northern Indian Ocean—and how these interactions regulate air-sea fluxes and marine heatwaves.

Longer-term challenges encompass integrating fine-scale dynamics into climate models and refining submesoscale parameterizations. Emerging tools from artificial intelligence and machine learning hold potential for representing unresolved processes and enhancing data assimilation. Finally, considering the logistical and financial requirements of fine-scale ocean research, sustained international collaboration will be indispensable.

—Lei Zhou (zhoulei1588@sjtu.edu.cn, 0000-0002-0433-3991) Shanghai Jiao Tong University, China; Dongxiao Wang (dxwang@mail.sysu.edu.cn, 0000-0001-8778-2188) Sun Yat-Sen University School of Marine Sciences, South China Sea Institute of Oceanology, China; Lin Wang (wanglin58@mail.sysu.edu.cn, 0009-0003-1062-5207) Sun Yat-Sen University, China; and Chunhua Qiu (qiuchh3@mail.sysu.edu.cn, 0000-0001-9684-6067)  Sun Yat-sen University School of Marine Sciences, China

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Zhou, L., D. Wang, L. Wang, and C. Qiu (2026), Small-scale Indian Ocean dynamics underpin marine ecology and climate, Eos, 107, https://doi.org/10.1029/2026EO265025. Published on 4 June 2026. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). 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.

SummaryMachine learning offers new opportunities for geophysical inverse problems, yet conventional regularized inversions of potential field data remain limited by global smoothing constraints and low structural resolution. We propose a locally adaptive, data-driven framework that combines synthetic Earth model generation and ensemble learning for joint gravity and magnetic interpretation. Training models are generated using geologically informed Voronoi-based geometries and planar structures, and a random forest classifier is trained on local statistical features of gravity and magnetic anomalies. The method yields geologically consistent subsurface models that reproduce observed anomaly characteristics without explicit regularization or iterative inversion. Compared with nonlinear Bayesian and traditional regularized inversions applied to the same dataset, the approach provides a substantial reduction in computational cost while preserving key structural features. The performance of the method is inherently linked to how representative the training ensemble is with respect to the target structure, and the results should be interpreted within this context. This framework demonstrates a practical and efficient alternative for potential field inversion using machine learning.

An international team of scientists has discovered that plants are not responding to global warming in the way researchers long assumed. Scientists have expected that ecosystems would keep pace with warming by raising the temperature at which photosynthesis works best.

El Niño is a recurring climate event with impacts across the globe. It has three phases: one cold (known as La Niña), one neutral, and one warm (El Niño).

Off the southern coast of Japan, the Philippine Sea Plate lies underneath the Japanese mainland. The locked tectonic plates threaten to unleash a catastrophic megathrust earthquake, likely within the next few decades. Given the potential devastation a large quake could evoke, constant developments in predictive technology must be sought. However, predicting the unpredictable movement of the seafloor requires innovative thought.

The Hadley circulation, a key atmospheric conveyor belt transporting heat and moisture from the tropics to the subtropics, directly influences subtropical aridity, the positions of tropical rainfall belts, and extreme weather risks. However, climate models have long shown inconsistencies in simulating its upper-level intensity (UP-HCI), undermining the reliability of future projections.

Many rivers flow into the Arctic Ocean north of the Arctic Circle—including the Lena in Siberia and the Mackenzie River in Canada. The deltas of these large and small rivers store large amounts of carbon, which is bound there in frozen soils and sediments. Climate change, however, is destabilizing the deltas from the ocean and land side and also from the air.

An international team of researchers including our Department of Geography has discovered a vast geological structure hidden beneath the East Antarctic Ice Sheet. The findings are published in the journal Nature Geoscience.

A new study in Nature Communications finds a critical climate tipping point in Tibetan permafrost ecosystems. Warming of 2–4 degrees Celsius triggers a self-reinforcing cycle of carbon release that could significantly accelerate climate change, according to the work.

Florida State University research published in Science Advances demonstrates a new framework for predicting the motion of kilometer-scale underwater waves that complicate satellite readings of the ocean.

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

The Trump administration’s National Science Foundation (NSF) has begun dismantling the infrastructure of a $368 million deep-ocean observing program critical to monitoring marine ecosystems, global currents, marine heat waves, and more, according to a 21 May announcement. 

The Ocean Observatories Initiative (OOI), funded by the NSF, has been collecting long-term oceanographic data at multiple deep-ocean sites since 2016. The information about ocean temperature, chemistry, currents, biological conditions, and more is used by scientists to understand a multitude of marine research questions including the activity of the Atlantic Meridional Overturning Circulation (AMOC), a critical ocean current.

“I worry that … we’ll be losing this enormously valuable site where we could really contextualize and detect these changes going forward.”

“There’s a real danger that we lose the ability to keep looking for long-term changes [in the ocean]” as climate change alters Earth systems, said Hilary Palevsky, a marine biogeochemist who has used OOI data for a decade to study how the ocean absorbs carbon dioxide. “I worry that … we’ll be losing this enormously valuable site where we could really contextualize and detect these changes going forward.”

The NSF plans to remove all in-water arrays and infrastructure—including hundreds of deep-sea instruments—from four of the five currently-operating sites within the project: the Global Station Papa Array (in the Gulf of Alaska), Coastal Endurance Array (off the coasts of Oregon and Washington), Global Irminger Sea Array (southeast of Greenland), and Coastal Pioneer Array (off the coast of North Carolina). The removal is expected to occur over the next 15 months, though the process has already begun at the Endurance Array. 

The National Science Foundation’s planned descoping of the Ocean Observatories Initiative will include dismantling four of the five currently operating arrays of equipment. Credit: NSF/OOI

The Trump administration attempted previously to downscale OOI operations, proposing to cut its funding in 2025 and 2026, though Congress never approved the cuts. 

The administration’s decision to dismantle the arrays “aligns with NSF’s wider strategy to have a nimbler approach to prioritizing support for evolving scientific priorities and emerging technologies as well as a deliberate approach to smart life cycle management within its portfolio of research infrastructure,” Michael England, an NSF spokesman, told the New York Times. 

A Dearth of Data

As each array is dismantled, data streams will end, though all previously collected data from OOI networks will remain accessible, Jim Edson, principal investigator for the OOI, wrote in a letter to the oceanographic community. 

Palevsky said there’s “a lot of real concern” among the oceanographic community that the Endurance Array is being dismantled just as an intense El Niño event—and associated marine heat wave—is expected this summer. “It would be especially important to be able to document the effect that [El Niño] is having on coastal physical circulation and ecosystems,” she said. 

 
Related

•  Announcement on NSF OOI Descoping
•  NSF OOI Descoping Update for the Community 
•  Trump Administration to Dismantle Ocean Monitoring System
•  Democrats Pledge to Fight Trump’s Removal of Ocean Monitors
•  Get Involved: AGU’s Science Policy Action Center 

“We encourage the community to use the ten-plus years of OOI data by including it in proposals, publications, presentations, and conversations with colleagues. Continued engagement demonstrates the scientific impact and wide-ranging applications enabled by the OOI and its data, underscoring its importance as a resource for the oceanographic community,” the 21 May announcement stated. 

There are other sources of data that researchers like Palevsky can use. But oceanographic research often requires stitching together different data sets, including OOI observations, satellite observations and observations from the U.S. research fleet. Many of these other sources of data are also facing uncertain futures. 

Palevsky also worries about the loss of expertise that will occur as the program scales down. Installing these deep-sea observing networks was a huge achievement for U.S. science that will not be easy to replicate, she said. “If, in five years, we as a community decide we want to again be able to deploy this kind of complicated infrastructure in places that have really difficult oceanographic conditions … it’s going to be a lot of reinventing the wheel to figure out how to put things out again.”

“The complete cessation without community input or a community conversation about what’s going to happen to all this equipment and what’s going to happen with all of the expertise,” she said, “feels like a huge loss.”

—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 how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. 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.

Scientists know that manganese, in its various oxide forms, plays a significant role in Earth's geochemical cycles. However, the exact forms of manganese, their abundance and the mechanisms behind these cycles that occur in Earth's deep, high-pressure interior are not well understood. But, a recent study, published in Physical Review B, reports on a newly discovered manganese rich compound that might help shed light on manganese's behavior in Earth's interior and explain why seismic waves slow down in certain regions.