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Four of the most important interconnected parts of the Earth's climate system are losing stability, according to a review article based on observational data published in Nature Geoscience. The researchers succeeded in highlighting the warning signals for destabilization of the Greenland Ice Sheet, the Atlantic Meridional Overturning Circulation (AMOC), the Amazon rainforest, and the South American monsoon system.

A large proportion of the carbon dioxide emissions that are currently being released into the atmosphere by human activities are absorbed by the surface ocean, making it more acidic. As a result, the tiny organisms (plankton), which lie at the base of the marine food web and make the surface ocean their home, are at risk. The fossil record can tell us how these plankton responded during ancient intervals of climatic change that were similarly associated with increased carbon dioxide emissions.

Wildfire smoke causes more air pollution than current atmospheric models can predict. A new study by researchers at King Abdullah University of Science and Technology (KAUST) and the Chinese Academy of Sciences explains why by revealing that, under sunlight, wildfire smoke particles act like tiny chemical factories, producing harmful oxidants such as peroxides, a group of highly reactive pollutants contributing to smog and haze.

More than 90% of plastic waste ends up in the soil, where it breaks down into microplastics that are invisible to the naked eye. Microplastic pollution of the soil poses a severe threat to soil health as it can harm essential microbial communities and reduce crop yields. The presence of these tiny plastics may also worsen climate change by boosting the production of greenhouse gases, according to a new study published in Environmental Science & Technology.

A team of researchers at the University of Miami has developed a global atmospheric modeling framework that blends powerful research capabilities with accessibility for students and scientists alike.

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.

At 12:01 a.m. this morning, the U.S. federal government shut down. This shutdown comes after weeks of negotiations and pressure tactics failed to bring Congressional Republicans and Democrats together on a budget for the 2026 fiscal year or a continuing resolution to fund the government for a few more weeks.

The federal government has experienced numerous shutdowns over the past decade, the longest of which happened during the first Trump administration and lasted 35 days.

This shutdown, however, may be different, and far more devastating, for the federal workers, including scientists, who live and work across the nation.

In a typical shutdown, employees and contractors who are deemed nonessential to government function, including most workers at science and science-adjacent agencies, are furloughed (temporarily suspended) without pay. Those whose jobs are deemed essential work without pay. Employees receive backpay when the shutdown lifts, but contractors do not.

As of this morning, the shutdown has been proceeding as before.

“The plan to exploit a shutdown to purge federal workers is illegal, unconstitutional, and deeply disturbing.”

But experts are watching how the Trump administration proceeds, as, earlier this week, it ordered all agencies to prepare plans for mass firings and reductions in force (RIFs), not furloughs, should a shutdown occur. According to the White House’s Office of Personnel Management, RIF plans must work within the budget outlined by the President’s Budget Request (PBR). On top of this, thousands of federal workers took offers of deferred resignation earlier this year and have been on paid leave for months. With the shutdown, they may be officially out of jobs.

Exceptions to the shutdown include departments that align with the president’s agenda and received money from his domestic policy megabill, such as the Department of Defense and the Department of Homeland Security, along with a few essential services like Medicare and Social Security.

Trump had doubled down on the threat to fire federal employees yesterday afternoon, which spurred a set of federal employee unions to file a lawsuit alleging that the threats are an unlawful abuse of power.

“The plan to exploit a shutdown to purge federal workers is illegal, unconstitutional, and deeply disturbing,” Tim Whitehouse, the executive director of Public Employees for Environmental Responsibility, said in a statement. “To weaponize it as a tool to destroy the civil service would mark a dangerous slide into lawlessness and further consolidate power in the Executive Branch.”

 
Related

•  From the Prow: AGU Statement on the U.S. Government Shutdown
•  How the Shutdown Is Affecting Federal Services and Workers
•  U.S. Scientists Gird for Yet Another Government Shutdown
•  Government Shutdown Threatens Further Destruction of Environment and Science Agencies, Advocates Warn
•  Get Involved: AGU Science Policy Action Center
 

These mass firing plans, poised to radically downsize and reshape the federal government, have not yet been implemented and it’s unclear if or when that will change. In preparation for possible firings, the Interior Department instructed employees to take home government laptops and cellphones to be able to receive updates.

Nonetheless, until this shutdown is resolved many federal science agencies have largely ceased operations or are working with very limited capacity. Some agencies that have submitted revised shutdown plans, like NOAA and the U.S. Geological Survey, have not yet received approval for the plans, leaving significant uncertainty about what parts of an agency will be allowed to legally operate.

Below is a nonexhaustive list of science-related agencies and how they are being affected by the shutdown.

• Environmental Protection Agency (EPA): An updated contingency plan from the EPA, posted 30 September, is much the same as in past years. Research at the EPA was already suffering: Staff cuts to the agency’s research arm, the Office of Research and Development, are expected to set back much of the agency’s research into environmental hazards, for example.
  • Under the plan, about 89% of EPA staff are now furloughed.
  • The plan calls for a cessation of new grants, updates to the EPA website and communications, all Superfund cleanup activities not necessary to safeguard human lives, inspections of industrial sites, and issuance of permits. Any research and publication activities not deemed necessary to maintain critical operations (such as care for lab animals, plants, and maintenance of instrumentation) must cease as well. Although not mentioned in the current plan, The New York Times notes that during past shutdowns, most employees responsible for monitoring pollution and ensuring industry compliance were furloughed.
  • Past EPA employees think the shutdown could also derail administrator Lee Zeldin’s plans to restructure the agency and revoke landmark EPA rules, such as the 2009 Endangerment Finding.
• National Aeronautics and Space Administration (NASA):
  • Per NASA’s shutdown plan, less than 17% of essential personnel will remain at work, tasked with protecting mission-critical assets such as spacecraft in orbit, astronauts aboard the International Space Station, and other safety operations. Research activities, educational support, and NASA Center tours will cease. NASA Television and the NASA.gov website will not be updated. The agency has requested an exemption from furlough for operations related to upcoming Artemis missions. Although a bipartisan group of lawmakers included a request in a proposed continuing resolution that NASA follow funding guidelines set in the appropriations bill passed by the House of Representatives, for now NASA is following the more severe PBR. Federal whistleblowers recently reported that NASA was illegally implementing the PBR before now, so this shutdown might lead to many spacecraft and their operators being terminated.
  • Proposals for the next observing cycle of the James Webb Space Telescope are due 15 October. The Space Telescope Science Institute has extended the deadline for scientists affected by the shutdown.
• National Oceanic and Atmospheric Administration (NOAA) and National Weather Service (NWS): NWS was chronically understaffed before January 2025 and staffing problems have only gotten worse this year. The current shutdown will likely deepen the existing strain on NWS staff and slow down the hiring process for new meteorologists and forecasters.
  • NWS will continue to issue weather warnings and watches, including those related to developing Atlantic storms. NWS and NOAA tours, outreach, and educational activities will cease. Hurricane Hunter crew and maintenance workers are exempted from being furloughed. Flights are expected to continue. Many employees who operate NOAA satellites are exempted from being furloughed. NOAA satellite data should continue to flow. Most NOAA research activities will cease.
  • If NOAA implements firings in line with the PBR, research related to climate, weather and air chemistry, habitat conservation, ocean science, coastal conservation, and the Great Lakes would be eliminated, as would the Office of Oceanic and Atmospheric Research (OAR).
• National Park Service (NPS): The most recent NPS shutdown contingency plan is from March 2024.
  • Activities related to law enforcement, emergency response, fire suppression and monitoring, and public safety should continue. Most national parks are not expected to close. However, some former park superintendents have asked people not to visit due to safety concerns and bad public behavior during past shutdowns. Visitor centers, bathrooms, trash collection, and park ranger services are now unavailable in most locations. No staff are maintaining trails, clearing brush, or monitoring wildlife. The majority of NPS staff are furloughed and some may soon be laid off.
  • Access to some wildlife refuges has been restricted.
• National Science Foundation (NSF):
  • According to a 2023 contingency plan for the agency, no new grants, cooperative agreements, or contracts are being awarded, and no new funding opportunities issued. The agency’s plan also calls for responses to any questions about upcoming grant deadlines to pause, so calls and emails won’t be answered. Scientists are still free to complete work that has already been funded, and the Award Cash Management Service, responsible for disbursing already-awarded funds, will still operate. However, funding decisions have been halted or delayed. Websites such as Grants.gov and Research.gov remain operational and will accept materials, but processing of those materials will be delayed.
  • NSF scientists temporarily working at the agency but paid by their home institutions are continuing to work.
• U. S. Forest Service (USFS):
  • A 2024 contingency plan from the agency calls for more than half its staff to remain active, as thousands of employees have been deemed necessary to protect life and property. Some USFS work to manage forests, such as reducing hazardous fuels, running fire training, planting new trees, or supervising controlled burns, will continue. However, the 2024 plan states that an extended shutdown could delay these activities, possibly impacting fire risk over hundreds of thousands of acres of forest as windows of favorable burn conditions dwindle.
  • Per the 2024 plan, USFS science, including experiments that rely on specific timing, such as prescribed burn studies, may face delay or cessation.
• U.S. Geological Survey (USGS):
  • In the past, USGS shutdown plans have called for all employees who are not deemed necessary to protect human lives and property to be furloughed, resulting in about half of the agency’s staff temporarily losing their paychecks. According to past contingency plans, some research activities at USGS are supported by supplemental funding from laws such as the Infrastructure Investment and Jobs Act and the Inflation Reduction Act. Such projects can continue. However, much of the USGS’s monitoring and analyzing of Earth systems and natural resources will cease.
  • Online access to USGS maps, publications, and data may be limited, including water quality data and Landsat data critical for emergency response, agriculture, Earth science research, and more.

“It’s incredibly difficult to predict what the federal research enterprise might look like on the other side.”

We don’t know how long this shutdown will last. But the Office of Management and Budget’s posture means “there are likely to be more questions than answers about the operating status of science agencies,” Cole Donovan, associate director of science & technology ecosystems at the Federation of American Scientists, wrote in an email to Eos. “It’s incredibly difficult to predict what the federal research enterprise might look like on the other side.”

Eos will be following news related to this shutdown and monitoring impacts to the federal workforce and larger scientific community. If you have a tip, suggestion, or personal story to share about how this shutdown has affected you, please email us at eos@agu.org.

–Grace van Deelen (@gvd.bsky.social) and Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writers

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 © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

California heads into the new water year facing continued risks from climate-driven extremes, the California Department of Water Resources said.

With unprecedented clarity, scientists have directly observed a subduction zone—the collision point where one tectonic plate dives beneath another—actively breaking apart. The discovery, reported in Science Advances, sheds new light on how Earth's surface evolves and raises fresh questions about future earthquake risks in the Pacific Northwest.

Almost a decade after NASA’s InSight mission put the first working seismometer on the Martian surface, researchers are still combing through its records of faint ground vibrations to reveal secrets of the planet’s deep interior.

In a recent analysis, scientists reported seismic evidence that Mars has a solid inner core, an unexpected finding that challenges earlier studies that suggested the planet’s core was entirely molten.

Like Earth—and onions and ogres—the interior of Mars has layers. These layers have different densities and can be solid or liquid. As seismic waves move through the layers, they are bent or reflected, especially at boundaries where density changes sharply. By analyzing how these waves propagate, scientists can trace their paths and infer the structure and properties of the materials they pass through.

Previous analyses of InSight data had already mapped the structure of the Martian crust and mantle and also revealed that the planet has a surprisingly large molten metallic core, spanning nearly half its radius. Such a large core, combined with measurements of the planet’s relatively low density, suggested that it must contain a lot of light elements such as sulfur, carbon, hydrogen, and oxygen. These light elements lower iron’s melting point, making it less likely to crystallize to form a solid inner core, which partly explains why the new finding caught InSight scientists off guard.

“None of us really believed that you would have a solid inner core,” said Amir Khan, a geophysicist at ETH Zurich who is part of the InSight science team but wasn’t involved in the new study.

A Long Way to the Core

Still, seismologist Daoyuan Sun of the University of Science and Technology of China in Hefei and his colleagues decided to look for signs of a solid core in the publicly available InSight data. Specifically, they reexamined data from a set of 23 marsquakes with seismic waves that passed through the planet’s core before returning to the surface.

To enhance the faint signals from the seismometer, the team combined—or stacked—recordings from these quakes. This revealed two types of compressional (P) waves that crossed the core. One set, known as P′P′ waves, traveled through the outer core to the farside of the planet, reflected off the surface there, and then passed back through the core to reach the seismometer. The other set, called PKKP waves, passed through the outer and inner core before being reflected back to the surface and encountering the core-mantle boundary on the way out.

“To me that’s the most exciting thing. That’s basically saying that you see this inner core structure. ”

Initially, the researchers could not find the PKKP waves at their expected arrival times. Instead, the waves were arriving 50–200 seconds earlier than predicted if the core was fully molten. The early arrivals suggested the waves had traveled through solid material, which transmits seismic P waves faster than liquids.

While looking for these early-arriving signals, the team also picked up a third set of seismic waves, called PKiKP. These are P waves that reflect back to the surface right at the boundary between the inner and outer core. This is the same type of seismic phase that seismologist Inge Lehmann used to reveal the existence of Earth’s solid inner core in 1936.

Finding these PKiKP waves in InSight data offered scientists a strong clue that Mars, too, may have a solid core.

“To me that’s the most exciting thing,” Sun said. “That’s basically saying that you see this inner core structure.”

By measuring the travel times of the seismic phases, Sun’s team estimated that Mars has a solid inner core with a radius of about 613 kilometers—roughly 18% percent of the radius of the planet itself. That ratio is very similar to that of Earth’s inner core, which is about 19% of Earth’s radius, and much larger than many researchers anticipated Mars could have. The new findings were published in Nature.

The team posited that their seismic observations could be explained by an outer core made up mostly of liquid or molten iron and nickel, as well as smaller amounts of sulfur and oxygen, and no more than 3.8% carbon, encasing a solid inner core enriched in more oxygen.

“It’s like Mars has lifted just the corner of its veil and allowed us to peek inside, but only a sneak peek—we could not get the full picture.”

These levels of light elements remain difficult for scientists to explain, Khan said. As light elements prefer to stay liquid, the existence of a solid inner core means that the outer core around it would have to be even richer in light elements than in previous models, which were already pushing the limits of what seemed plausible. On top of that, the building blocks from which scientists think Mars formed don’t contain enough of these elements to account for the abundance required by a solid core, Khan added.

The finding is also at odds with two studies published 2 years ago, one of them led by Khan, that proposed that a layer of molten rock sits at the bottom of the mantle, just above the core, insulating it like a thermal blanket. Such a layer would keep the core hotter, making it more difficult for it to crystallize and solidify.

“It’s like Mars has lifted just the corner of its veil and allowed us to peek inside, but only a sneak peek—we could not get the full picture,” Khan said. “We are not there yet.”

A Hibernating Dynamo

The new finding also renews questions about the absence of a global magnetic field on Mars. Earth’s magnetic field is sustained by the slow crystallization of the core, which drives magnetism-inducing convective motions in the liquid outer core. We know that Mars once had a magnetic field, but it died out billions of years ago.

If Mars does have a solid inner core, why is its magnetic dynamo inactive?

The likely reason is that core crystallization, and thus convection in the outer core, is too slow to power a global magnetic field on Mars, said Douglas Hemingway, a planetary scientist at the University of Texas at Austin and a coauthor of the new study. Mars’s early magnetic field was likely powered by primordial heat escaping from its core. As the planet cooled over billions of years, this convection weakened, and the magnetic field eventually disappeared.

Finding a solid core on Mars, however, opens up the intriguing possibility of a global magnetic field eventually reigniting, Hemingway said. The process of crystallization happens at the boundary of the outer core and the inner core, and if this surface grows larger over time, it could reach a point where there’s enough convective motion to kick-start the dynamo and revive the global magnetic field.

In earlier work, Hemingway predicted that if the Martian core is crystallizing from the center outward, the magnetic field could turn on sometime within the next billion years. “So, you know, if we wait a billion years and it doesn’t happen, then we were wrong,” he joked.

There may be no definitive confirmation of the existence of a solid core on Mars for a long time. The InSight mission ended in 2022, after dust piling up on the lander’s solar panels drained the device’s power supply, and new seismic data from Mars won’t be available for decades, most likely.

“Maybe when we send humans, we would be motivated to bring a few seismometers,” Hemingway said.

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

Citation: Barbuzano, J. (2025), Scientists may have finally detected a solid inner core on Mars, Eos, 106, https://doi.org/10.1029/2025EO250367. Published on 1 October 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryFlooding of abandoned excavation mines implies significant changes in the hydromechanic rock behavior often associated with instantaneous rock instabilities which cause underground and ground failure and collapses, sometimes (but not always) accompanied by induced seismicity. The permanent modification of the hydrogeological setting may, in certain cases, also induce long-term seismic activities persistent over several years. The governing hydromechanic triggering mechanisms are poorly understood in these cases what bares challenges in related seismic hazard and risk assessment. In this study, we provide new insights into this poorly explored field of fluid induced seismicity, by investigating the long-lasting (> 10 years) swarm activity induced by the flooding of an abandoned coal mine at Gardanne in Southern France. The strongest events of the activity have comparatively small magnitudes (Mw < 2) but are felt by the local population due to their shallow source depth (< 1 km). Thanks to full waveform based source analysis we show that the swarm is associated with the permanent activation of preexisting faults situated below the flooded mining voids which act as a very high-capacity anthropogenic reservoir and aquifer. We further show that mine water level changes caused by either natural or anthropogenic driving forces cause seismic triggering which involves direct pore-pressure as well as poroelastic effects. These findings provide constraints for adequate guidelines for safe mine water level management and seismic risk mitigation.

SummaryHigh-resolution seismic reflections are essential for imaging and monitoring applications. In seismic land surveys using sources and receivers at the surface, surface waves often dominate, masking the reflections. In this study, we demonstrate the efficacy of a two-step procedure to suppress surface waves in an active-source reflection seismic dataset. First, we apply seismic interferometry (SI) by cross-correlation, turning receivers into virtual sources to estimate the dominant surface waves. Then, we perform adaptive subtraction to minimise the difference between the surface waves in the original data and the result of SI. We propose a new approach where the initial suppression results are used for further iterations, followed by adaptive subtraction. This technique aims to enhance the efficacy of data-driven surface-wave suppression through an iterative process. We use a 2D seismic reflection dataset from Scheemda, situated in the Groningen province of the Netherlands, to illustrate the technique’s efficiency. A comparison between the data after recursive interferometric surface-wave suppression and the original data across time and frequency-wavenumber domains shows significant suppression of the surface waves, enhancing visualization of the reflections for subsequent subsurface imaging and monitoring studies.

Scientists at King Abdullah University of Science and Technology (KAUST) have provided conclusive evidence that the Red Sea completely dried out about 6.2 million years ago, before being suddenly refilled by a catastrophic flood from the Indian Ocean. The findings put a definitive time on a dramatic event that changed the Red Sea.

Long-term weather forecasting is a difficult task, partly because weather systems are inherently chaotic. Though mathematical equations can approximate the underlying physics of weather, tiny inaccuracies that grow exponentially as a model progresses in time limit most physics-based forecasts to 2 weeks or less.

While publicly registered drinking water must meet government standards and regulations, people accessing private groundwater bores and springs supplying 25 or fewer people have no requirements to test their drinking water. Most of these groundwater self-supplies are found in rural areas and are vulnerable to nitrate contamination, leaving communities at risk if left untested.

On the edge of California's Monterey Bay, ecologist Matthew Savoca and a team of volunteers sift through sand and seawater for microplastics, one of the planet's most pervasive forms of pollution.

Air quality in America's largest cities has steadily improved thanks to tighter regulations on key sources of particulate pollution. However, increased heat, wildfire smoke and other emerging global drivers of urban aerosol pollution are now combining to create a new set of challenges for public health officials tasked with protecting millions of people on the East Coast.

In July 2024, a 7.4-magnitude earthquake struck Calama, Chile, damaging buildings and causing power outages. The country has endured violent earthquakes, including the most powerful recorded in history: a 9.5-magnitude "megathrust" event that struck central Chile in 1960, causing a tsunami and killing between 1,000 to 6,000 people. However, the Calama quake was different from the megathrust quakes that are usually associated with the most destructive events in Chile and around the world.

The Earth became darker from 2001 to 2024, meaning it reflects less sunlight, a research team reports in the journal Proceedings of the National Academy of Sciences.

On September 5, 2020, California's Creek Fire grew so severe that it began producing its own weather system. The fire's extreme heat produced an explosive thunderhead that spewed lightning strikes and further fanned the roaring flames, making containment elusive and endangering the lives of firefighters on the ground. These wildfire-born storms have become a growing part of fire seasons across the West, with lasting impacts on air quality, weather, and climate.

Source: Journal of Geophysical Research: Machine Learning and Computation

Long-term weather forecasting is a difficult task, partly because weather systems are inherently chaotic. Though mathematical equations can approximate the underlying physics of weather, tiny inaccuracies that grow exponentially as a model progresses in time limit most physics-based forecasts to 2 weeks or less.

Estimated values called parameters, which are used to represent the effects of specific physical processes, are important ingredients in these equations. Parameters are inferred by physical data and affect model outcomes by, for example, multiplying or giving different weights to measurements of temperatures, winds, or other factors.

In recent years, artificial intelligence (AI)–based models such as GraphCast and FourCastNet have transformed weather prediction with their ability to learn from large amounts of weather data and produce highly accurate predictions of future weather. However, AI-based models typically contain tens of millions to hundreds of millions of parameters that do not directly translate to underlying physical processes. Because these parameters are not interpretable by researchers, such AI models make only limited contributions to the scientific understanding of weather.

Minor et al. address this limitation by demonstrating the capabilities of a Weak form Scientific Machine Learning (WSciML) algorithm known as Weak form Sparse Identification of Nonlinear Dynamics (WSINDy). Like other AI methods, WSINDy learns from data. But instead of using a highly parameterized approach, it discovers mathematical equations that represent complex, real-world physical processes, such as how air pressure, density, and vorticity interact to determine wind speed and direction.

The researchers applied WSINDy to both simulated and real-world turbulent atmospheric fluid data, which include measurements of temperature, pressure, and wind speed. WSINDy used the artificial data to identify the known equations from the simulation. Most important, WSINDy was also able to successfully identify the governing equations of the known atmospheric physics from a global-scale set of assimilated data incorporating real-world weather observations.

These findings suggest that WSINDy could not only aid in weather forecasting but also help uncover new physical insights about weather, the researchers say. They also note that WSINDy is especially well suited for application to data with high levels of observational noise.

However, further work will be needed to refine WSINDy so it can identify more accurately certain kinds of known atmospheric equations, such as realistic models for atmospheric wind, the researchers say. The algorithm is also being explored for use across a wide range of other scientific areas, including unexplained phenomena in fusion, population behaviors driving epidemics, and communication between cells that leads to collective motion in wound healing. (Journal of Geophysical Research: Machine Learning and Computation, https://doi.org/10.1029/2025JH000602, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Unveiling what’s under the hood in AI weather models, Eos, 106, https://doi.org/10.1029/2025EO250365. Published on 30 September 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.