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Solid as they are, rocks are not static materials with constant properties. Even small loads are enough to alter their mechanical properties; their reaction to being deformed is a loss of stiffness. Rocks which have been damaged in such a way are then less able to withstand loads, such as gravity or tectonic stresses. This phenomenon is therefore of relevance for understanding the occurrence of material failure, as in landslides or earthquakes.

Materials scientists at the University of California San Diego have performed powerful laser shock experiments on a perovskite mineral to better understand the geophysical processes in Earth's deep interior and the mechanisms behind earthquakes deep within the planet.

On 28 August 2005, New Orleans area residents received a bulletin from the National Weather Service (NWS) office in Slidell, La., warning them of “a most powerful hurricane with unprecedented strength.” One excerpt of the chilling announcement, issued via NOAA radio and the Federal Communications Commission’s Emergency Alert Service, read,

BLOWN DEBRIS WILL CREATE ADDITIONAL DESTRUCTION. PERSONS…PETS…AND LIVESTOCK EXPOSED TO THE WINDS WILL FACE CERTAIN DEATH IF STRUCK.

POWER OUTAGES WILL LAST FOR WEEKS…AS MOST POWER POLES WILL BE DOWN AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS.

Hurricane Katrina, which caused 1,833 fatalities and about $108 billion in damage (more than $178 billion in 2025 dollars), remains the costliest hurricane on record to hit the United States and among the top five deadliest.

“If we were to have a Katrina today, that [forecast] cone would be half the size that it was in 2005.”

In the 20 years since the hurricane, meteorologists, modelers, computer scientists, and other experts have worked to improve the hurricane forecasting capabilities that inform bulletins like that one.

Consider the forecast cone, for instance. Also known as the cone of uncertainty, this visualization outlines the likely path of a hurricane with decreasing specificity into the future: The wider part of the cone might represent the forecasted path 36 hours in advance, and the narrower part might represent the forecasted path 12 hours in advance.

“If we were to have a Katrina today, that cone would be half the size that it was in 2005,” said Jason Beaman, meteorologist-in-charge at the National Weather Service Mobile/Pensacola office.

How to Make a Hurricane

The ingredients for a hurricane boil down to warm water and low pressure. When an atmospheric low-pressure area moves over warm ocean water, surface water evaporates, rises, then condenses into clouds. Earth’s rotation causes the mass of clouds to spin as the low pressure pulls air toward its center.

Storms born in the Gulf of Mexico or that traverse it, as Katrina did, benefit from the body’s sheltered, warm water, and the region’s shallow continental shelf makes storm surges particularly destructive for Gulf Coast communities.

Hurricanes gain strength as long as they remain over warm ocean waters. But countless factors contribute to how intense a storm becomes and what path it takes, from water temperature and wind speed to humidity and proximity to the equator.

Because predicting the behavior of hurricanes requires understanding how they work, data gathered by satellites, radar, and aircraft are crucial for researchers. Feeding these data into computer simulations helps researchers understand the mechanisms behind hurricanes and predict how future storms may behave.

“Since 2005, [there have been] monumental leaps in observation skill,” Beaman said.

Seeing a Storm More Clearly

Many observations of the weather conditions leading up to hurricanes come from satellites, which can offer a year-round bird’s-eye view of Earth.

NOAA operates a pair of geostationary satellites that collect imagery and monitor weather over the United States and most of the Atlantic and Pacific oceans. The mission, known as the Geostationary Operational Environmental Satellite (GOES) program, has been around since 1975; the current satellites are GOES-18 and GOES-19.

When Beaman started his career just a few years before Katrina hit, satellite imagery from GOES-8 to GOES-12 was typically beamed to Earth every 30–45 minutes—sometimes as often as every 15 minutes. Now it’s routine to receive images every 5 minutes or even as often as every 30 seconds. Having more frequent updates makes for much smoother animations of a hurricane’s track, meaning fewer gaps in the understanding of a storm’s path and intensification.

For Beaman, the launch of the GOES-16 satellite in 2016 marked a particularly important advance: In addition to beaming data to scientists more frequently, it scanned Earth with 4 times the resolution of the previous generation of satellites. It could even detect lightning flashes, which can sometimes affect the structure and intensity of a hurricane.

The transition to GOES-16 “was like going from black-and-white television to 4K television.”

The transition to GOES-16 “was like going from black-and-white television to 4K television,” Beaman said.

NOAA also has three polar-orbiting satellites, launched between 2011 and 2017, that orbit Earth from north to south 14 times a day. As part of the Joint Polar Satellite System (JPSS) program, the satellites’ instruments collect data such as temperature, moisture, rainfall rates, and wind for large swaths of the planet. They also provide microwave imagery using radiation emitted from water droplets and ice. NOAA’s earlier polar-orbiting satellites had lower resolution at the edges of scans, a more difficult time differentiating clouds from snow and fog, and less accurate measurements of sea surface temperature.

“With geostationary satellites, you’re really just looking at the cloud tops,” explained Daniel Brown, branch chief of the Hurricane Specialist Unit at NOAA’s National Hurricane Center in Miami. “With those microwave images, you can really kind of see into the storm, looking at structure, whether an eye has formed. It’s really helpful for seeing the signs of what could be rapid intensification.”

NOAA’s Geostationary Operational Environmental Satellites (GOES) monitor weather over the United States and most of the Atlantic and Pacific oceans. Credit: NOAA/Lockheed Martin, Public Domain

Rapid intensification is commonly defined as an increase in maximum sustained wind speed of 30 or more nautical miles per hour in a 24-hour period. Katrina had two periods of rapid intensification, and they were one reason the storm was so deadly. In the second period, the storm strengthened from a low-end category 3 hurricane (in which winds blow between 178 and 208 kilometers per hour, or between 111 and 129 miles per hour) to a category 5 hurricane (in which winds blow faster than 252 kilometers per hour, or 157 miles per hour) in less than 12 hours.

New Angles

Radar technology has also made strides in the decades since Katrina. Hurricane-tracking radar works via a ground- or aircraft-based transmitter sending out a radio signal. When the signal encounters an obstacle in the atmosphere, such as a raindrop, it bounces back to a receiver. The amount of time it takes for the signal to return provides information about the location of the obstacle.

Between 2011 and 2013, NWS upgraded its 150+ ground-based radars throughout the United States with dual-polarization technology—a change a 2013 NWS news release called “the most significant enhancement made to the nation’s radar network since Doppler radar was first installed in the early 1990s.”

So-called dual-pol technology sends both horizontal and vertical pulses through the atmosphere. With earlier technology, a radar signal might tell researchers only the location of precipitation. Dual-pol can offer information about how much precipitation is falling, the sizes of raindrops, and the type of precipitation or can even help researchers identify debris being transported in a storm.

Credit: NOAA

“That’s not something that we had back in Katrina’s time,” Beaman said. In 2005, forecasters used “much more crude ways of trying to calculate, from radar, how much rain may have fallen.”

Radar updates have become more frequent as well. Beaman said his office used to receive routine updates every 5 or 6 minutes. Now they receive updated radar imagery as often as every minute.

Hunting Hurricanes from the Skies

For a more close-up view of a hurricane, NOAA and the U.S. Air Force employ Hurricane Hunters—planes that fly directly through or around a storm to take measurements of pressure, humidity, temperature, and wind speed and direction. These aircraft also scan the storms with radar and release devices called dropwindsondes, which take similar measurements at various altitudes on their way down to the ocean.

NOAA’s P-3 Orion planes and the 53rd Weather Reconnaissance Squadron’s WC-130J planes fly through the eyes of storms. NOAA’s Gulfstream IV jet takes similar measurements from above hurricanes and thousands of square kilometers around them, also releasing dropwindsondes along the way. These planes gather information about the environment in which storms form. A 2025 study showed that hurricane forecasts that use data from the Gulfstream IV are 24% more accurate than forecasts based only on satellite imagery and ground observations.

The NOAA P-3 Hurricane Hunter aircraft captured this image from within the eye of Hurricane Katrina on 28 August 2005, 1 day before the storm made landfall. Credit: NOAA, Public Domain

Hurricane Hunters’ tactics have changed little since Katrina, but Brown said that in the past decade or so, more Hurricane Hunter data have been incorporated into models and have contributed to down-to-Earth forecasting.

Sundararaman “Gopal” Gopalakrishnan, senior meteorologist with NOAA’s Atlantic Oceanographic and Meteorological Laboratory’s (AOML) Hurricane Research Division, emphasized that Hurricane Hunter data have been “pivotal” for improving both the initial conditions of models and the forecasting of future storms.

With Hurricane Hunters, “you get direct, inner-core structure of the storm,” he said.

Hurricane Hunters are responsible for many of the improvements in hurricane intensity forecasting over the past 10–15 years, said Ryan Torn, an atmospheric and environmental scientist at the University at Albany and an author of the recent study about Gulfstream IVs. One part of this improvement, he explained, is that NOAA began flying Hurricane Hunters not just for the largest storms but for weaker and smaller ones as well, allowing scientists to compare what factors differentiate the different types.

“We now have a very comprehensive observation dataset that’s come from years of flying Hurricane Hunters into storms,” he said. These datasets, he added, make it possible to test how accurately a model is predicting wind, temperature, precipitation, and humidity.

In 2021, NOAA scientists also began deploying uncrewed saildrones in the Caribbean Sea and western Atlantic to measure changes in momentum at the sea surface. The drones are designed to fill observational gaps between floats and buoys on the sea surface and Hurricane Hunters above.

Modeling Track and Intensity

From the 1980s to the early 2000s, researchers were focused on improving their ability to forecast the path of a hurricane, not necessarily what that hurricane might look like when it made landfall, Gopalakrishnan explained.

Brown said a storm’s track is easier to forecast than its intensity because a hurricane generally moves “like a cork in the stream,” influenced by large-scale weather features like fronts, which are more straightforward to identify. Intensity forecasting, on the other hand, requires a more granular look at factors ranging from wind speed and air moisture to water temperature and wind shear.

Storms like 2005’s Katrina and Rita “showed the importance of [tracking a storm’s] intensity, especially rapid intensification.”

Gopalakrishnan said storms like 2005’s Katrina and Rita “showed the importance of [tracking a storm’s] intensity, especially rapid intensification.”

Without intensity forecasting, Gopalakrishnan said, some of the most destructive storms might appear “innocuous” not long before they wreak havoc on coastlines and lives. “Early in the evening, nobody knows about it,” he explained. “And then, early in the morning, you see a category 3 appear from nowhere.”

Gopalakrishnan came to AOML in 2007 to set up both the Hurricane Modeling Group and NOAA’s Hurricane Forecast Improvement Project. He had begun working on what is now known as the Hurricane Weather Research Forecast model (HWRF) in 2002 in his role at NOAA’s Environmental Modeling Center. With the formation of the hurricane modeling group in 2007, scientists decided to focus on using HWRF to forecast intensity changes.

HWRF used a technique called moving nests to model the path of a storm in higher resolution than surrounding areas. Gopalakrishnan compared a nest to using a magnifying glass focused on the path of a storm. Though a model might simulate a large area to provide plenty of context for a storm’s environment, capturing most of an area in lower resolution and the storm path itself in higher resolution can save computing power.

By 2014, Gopalakrishnan said, the model’s tracking and intensity forecasting capabilities had improved 25% since 2007. The model’s resolution also upgraded from 9 square kilometers in 2007 to 1.5 square kilometers by the time it was retired in 2023.

Since 2007, the National Hurricane Center’s official (OFCL) track forecast errors decreased between 30% and 50%, and intensity errors shrank by up to 55%. MAE = mean absolute error; VMAX = maximum sustained 10-meter winds. Credit: Alaka et al., 2024, https://doi.org/10.1175/BAMS-D-23-0139.1

Over time, advances in how data are introduced into models meant that the better data researchers were receiving from satellites, radars, and Hurricane Hunters improved modeling abilities even further. Gopalakrishnan estimated that by 2020, his office could predict hurricane track and intensity with somewhere between 50% and 54% more accuracy than in 2007.

NOAA began transitioning operations to a new model known as the Hurricane Analysis and Forecast System (HAFS) in 2019, and HAFS became the National Hurricane Center’s operational forecasting model in 2023. HAFS, developed jointly by several NOAA offices, can more reliably forecast storms, in part by increasing the use of multiple nests—or multiple high-resolution areas in a model—to follow multiple storms at the same time. HAFS predicted the rapid intensification of Hurricanes Helene and Milton in 2024.

Just as they did with HWRF, scientists run multiple versions of HAFS each year: an operational model, used to inform the public, and a handful of experimental models to see which of them work the best. At the end of hurricane season, researchers examine which versions performed the best and begin combining elements to develop the next generation of the operational model. The team expects that as HAFS improves, it will lengthen the forecast from the 5 days offered by previous models.

“As a developer [in 2007], I would have been happy to even get 2 days forecast correctly,” Gopalakrishnan said. “And today, I’m aiming to get a 7-day forecast.”

NOAA’s budget plan for 2026 could throw a wrench into this progress, as it proposes eliminating all NOAA labs, including AOML.

The Role of Communication

An accurate hurricane forecast does little good if the information isn’t shared with the people who need it. And communication about hurricane forecasts has seen its own improvements in the past 2 decades. NWS has partnered with social scientists to learn how to craft the most effective messages for the public, something Beaman said has paid dividends.

Communication between the National Hurricane Center and local weather service offices can be done over video calls, rather than by phone as was once done. Sharing information visually can make these calls more straightforward and efficient. NWS began sending wireless emergency alerts directly to cell phones in 2012.

In 2017, the National Hurricane Center began issuing storm surge watches and warnings in addition to hurricane watches and warnings. Beaman said storm surge inundation graphics, which show which areas may experience flooding, may have contributed to a reduction in storm surge–related fatalities. In the 50-year period between 1963 and 2012, around 49% of storm fatalities were related to storm surge, but by 2022, that number was down to 11%.

“You take [the lack of visualization] back to Katrina in 2005, one of the greatest storm surge disasters our country has seen, we’re trying to express everything in words,” Beaman said. “There’s no way a human can properly articulate all the nuances of that.”

Efforts to create storm data visualization go beyond NOAA.

Carola and Hartmut Kaiser moved to Baton Rouge, La., just weeks before Hurricane Katrina made landfall. Hartmut, a computer scientist, and Carola, an information technology consultant with a cartography background, were both working at Louisiana State University. When the historic storm struck, Hartmut said they wondered, “What did we get ourselves into?”

Shortly after the storm, the Kaisers combined their expertise and began work on the Coastal Emergency Risks Assessment (CERA). The project, led by Carola, is an easy-to-use interface that creates visual representations of data, including storm path, wind speed, and water height, from the National Hurricane Center, the Advanced Circulation Model (ADCIRC), and other sources.

The Coastal Emergency Risks Assessment tool aims to help the public understand the potential timing and impacts of storm surge. Here, it shows a forecast cone for Hurricane Erin in August 2025, along with predicted maximum water height levels. Credit: Coastal Emergency Risks Assessment

“We know of a lot of people who said, ‘Yes, thank you, [looking at CERA] caused me to evacuate.”

What started as an idea for how to make information more user-friendly for the public, emergency managers, and the research community grew quickly: Hundreds of thousands of people now use the tool during incoming storm events, Hartmut said. The Coast Guard often moves its ships to safe regions on the basis of CERA’s predictions, and the team frequently receives messages of thanks.

“We know of a lot of people who said, ‘Yes, thank you, [looking at CERA] caused me to evacuate,” Hartmut said. “And now my house is gone, and I don’t know what would have happened if I didn’t go.”

Looking Forward

Unlike hurricane season itself, the work of hurricane modelers has no end. When the season is over, teams such as Gopalakrishnan’s review the single operational and several experimental models that ran throughout the season, then work all year on building an upgraded operational model.

“It’s 365 days of model developments, testing, and evaluation,” he said.

NOAA scientists aren’t the only ones working to improve hurricane forecasting. For instance, researchers at the University of South Florida’s Ocean Circulation Lab (OCL) and the Florida Flood Hub created a storm surge forecast visualization tool based on the lab’s models. The West Florida Coastal Ocean Model, East Florida Coastal Ocean Model, and Tampa Bay Coastal Ocean Model were designed for the coastal ocean with a sufficiently high resolution to model small estuaries and shipping channels.

Though Yonggang Liu, a coastal oceanographer and director of OCL, cited examples of times his lab’s models have outperformed NOAA’s models, the tool is not used in operational NOAA forecasts. But it is publicly available on the OCL website (along with a disclaimer that the analyses and data are “research products under development”).

The Cyclone Global Navigation Satellite System (CYGNSS) is a NASA mission that pairs signals from existing GPS satellites with a specialized radar receiver to measure reflections off the ocean surface—a proxy for wind levels. The constellation of eight satellites can take measurements more frequently than GOES satellites, allowing for better measurement of rapid intensification, said Chris Ruf, a University of Michigan climate and space scientist and CYGNSS principal investigator.

It might seem that if a method or mission offers a way to more accurately forecast hurricanes, it should be promptly integrated into NOAA’s operational models. But Ruf explained NOAA’s hesitation to use data from university-led efforts: Because they are outside of NOAA’s control and could therefore lose funding or otherwise stop running, it’s too risky for NOAA to rely on such projects.

“CYGNSS is a one-off mission that was funded to go up there and do its thing, and then, when it deorbits, it’s over,” Ruf said. “They [at NWS] don’t want to invest a lot of time learning how to assimilate some new data source and then have the data disappear later. They want to have operational usage where they can trust that it’s going to be there later on.”

“These improvements cannot happen as a one-man army.”

Whatever office they’re in, it’s scientists who make the work of hurricane forecasting possible. Gopalakrishnan said that during Katrina, there were two or three people at NOAA associated with model development. He credits the modeling improvements made since then to the fact that, now, there’s a team of several dozen. And more advances may be on the horizon. For instance, NOAA expects a new Hurricane Hunter jet, a G550, to join the ranks by 2026.

However, some improvements are stalling. The Geostationary Extended Observations (GeoXO) satellite system is slated to begin expanding observations of GOES satellites in the early 2030s. But the 2026 U.S. budget proposal, which suggests slashing $209 million from NOAA’s efforts to procure weather satellites and infrastructure, specifically suggests a “rescope” of the GeoXO program

Hundreds of NOAA scientists have been laid off since January 2025, including Hurricane Hunter flight directors and researchers at AOML (though NWS received permission to rehire hundreds of meteorologists, hydrologists, and radar technicians, as well as hire for previously approved positions, in August).

In general, hurricane fatalities are decreasing: As of 2024, the 10-year average in the United States was 27, whereas the 30-year average was 51. But this decrease is not because storms are becoming less dangerous.

“Improved data assimilation, improved computing, improved physics, improved observations, and more importantly, the research team that I could bring together [were] pivotal” in enabling the past 2 decades of forecasting improvements, said Gopalakrishnan. “These improvements cannot happen as a one-man army. It’s a team.”

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

Citation: Dieckman, E. (2025), How researchers have studied the where, when, and eye of hurricanes since Katrina, Eos, 106, https://doi.org/10.1029/2025EO250320. Published on 28 August 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.

Wakeboats are causing a stir in Minnesota.

Though all powerboats create wakes, these specialty craft have heavier sterns and engines specifically designed to shape water into surfable waves. That extra turbulence is drawing ire from other lake-lovers.

Across the state, Minnesotans are reporting eroding banks, murky waters, and shredded vegetation. When considering wakeboats, one person’s recreation is another’s resentment.

“It’s divisive,” said Joe Shneider, president of the Minnesota Coalition of Lake Associations. “The three big issues we hear all the time [about wakeboats] are personal safety, bank erosion, and lake bed disruption.”

Specialty wakeboats are designed to shape water into surfable waves, allowing riders to follow behind without needing a towrope. New research shows how those wakes can affect the lake bed below. Credit: Colin Van Dervort/Flickr, CC BY 2.0

As the popularity and size of wakeboats grow, so does the need for data. Communities are wrestling with issues of regulation and education, and both approaches require information. That’s why Shneider and more than 200 others helped crowdfund recent research from the University of Minnesota’s Saint Anthony Falls Laboratory. (The state also supported the project.) The resulting public dataset shows how wakeboats can churn lake beds, information that can help communities navigate the brewing conflict.

The Stakes

Minnesota is not the only state navigating a great wake debate. In 2024, Maine implemented wakeboat regulations and Vermont restricted wake surfing to its 30 largest lakes. (Some residents want the number further reduced to 20.) In Wisconsin, individual municipalities are debating bans on wake surfing at hundreds of lakes, prompting at least one lawsuit.

Minnesota, in contrast, has issued wakeboat regulations at only one of its 10,000 lakes.

“There’s a whole lot of people out there that need to make decisions about their lake.”

The environmental issues at stake arise in shallow water, where powerboats can stir up obvious trails of sediment. Resuspended sediment absorbs sunlight, which heats the water column. Turbidity reduces the feeding rates of some fishes. Once-buried nutrients again become available, triggering toxic algal blooms that choke beaches and rob fish of oxygen.

But to connect the dots between wakeboat use and ecosystem disruption, researchers needed to document how various powerboats affect sediment dispersal.

“We want to understand how boats are interacting with the water column and provide data, because there’s a whole lot of people out there that need to make decisions about their lake,” said Jeff Marr, a hydraulic engineer at the University of Minnesota and a coauthor of the study.

The Wake

On Lake Minnetonka, just west of Minneapolis, seven locals lent their boats for the research. These watercraft ranged from relatively light, low-power deck boats (150-horsepower, 2,715 pounds) to burly bowriders (760-horsepower, 14,530 pounds) and included two boats built for wake surfing.

On test days, volunteers piloted their boats between buoy-marked goalposts. Acoustic sensors on the lake bed tracked pressure changes in the water column.

Powerboats mostly operate at either displacement speed (chugging low in the water) or planing speed (skipping faster along the surface). But there’s a transition called semidisplacement, in which the stern sinks in the water and waves spike in size.

“It’s right at that transition that [wakeboats] like to operate,” said Andy Riesgraf, an aquatic biologist at the University of Minnesota and a coauthor of the study.

Boaters drove the course five times at planing speed (21–25 miles per hour, common for water-skiing and tubing) and five times at displacement or semidisplacement mode (7–11 miles per hour, common for cruising and wake surfing). Researchers in rowboats paddled to collect water samples at various intervals in the track.

Researchers Chris Feist and Jessica Kozarek stand by the research rowboat. To minimize disruption in the water column, the human-powered sampling team paddled into the wake racetrack to collect 1-liter water samples at three different depths. Credit: Saint Anthony Falls Laboratory

The acoustic sensors showed that three types of waves affected the water column. Pressure waves, created by the immediate shift and rebound of water around a boat, were short-lived but strong enough to shake loose sediments. Transverse waves, which follow the boat’s path, and propeller wash, the frothy vortex generated by its engines, both elevated loose sediment and caused minutes-long disturbances.

Though all boats created these waves, the wakeboats churned the most sediment.

In planing mode, all seven boats caused brief and minimal disturbances. Sediments settled in less than 10 seconds at 9- and 14-foot depths. But when operating in slower, semidisplacement mode, wakeboats created a distinct disturbance. Following a pass from a wakeboat, sediment needed 8 minutes to settle at 14-foot depth and more than 15 minutes at 9-foot depth.

The research team released simple recommendations based on their findings. One recommendation is that all recreational powerboats should operate in at least 10 feet of water to minimize disturbances. Another is that wakeboats, when used for surfing, need 20 feet of water to avoid stirring up sediments and altering the ecosystem.

The Uptake

The new research adds to the group’s existing dataset on powerboats’ hydrologic impacts on lake surfaces.

Whether the suggestions lead to regulations is up to lake managers.

“Our goal is just to get the data out,” Marr said. The researchers published their findings in the University of Minnesota’s open-access digital library so that everyday lake-goers can find the information. Three external experts reviewed the material.

The more we continue to collect these data, the more that we start to fill in those other gaps.

The results add information to the policy debate. “If there is going to be some type of environmental regulation [on powerboating], you need very clear evidence that under these conditions, it’s detrimental,” said Chris Houser, a coastal geomorphologist at the University of Waterloo who was not involved in the project.

There are other variables to study—such as the number of boats on the water and the paths they’re carving—but “the more we continue to collect this data, the more we start to fill in those other gaps of different depths and different configurations,” Houser said.

For Shneider, the new data add much-needed clarity. The latest report “is monumental,” he said.

Marr, Riesgraf, and their colleagues are now comparing the impacts of boat-generated wakes against wind-driven waves. Those data could further isolate the impacts powerboats have on lakes.

—J. Besl (@J_Besl, @jbesl.bsky.social), Science Writer

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Citation: Besl, J. (2025), A debate over wakes in the land of 10,000 lakes, Eos, 106, https://doi.org/10.1029/2025EO250316. Published on 29 August 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.

SummaryWe demonstrate a method for the prediction of seismic discontinuity topography from thermochemical Mantle Circulation Models (MCMs). We find the discontinuity depth by using the peak reflectivity at each location in our mantle transition zone, taking account of compositional as well as thermal variations. We make some comparisons of our predicted topographies with those observed using SS-precursors, developing a simple smoothing filter to capture the distribution of sensitivity of a published topography model – finding that such filtering has a significant impact on the predicted discontinuity topographies. We also consider the significance of lateral variations in reflectivity or reflection amplitude in our predicted datasets and the real Earth. Finally, we consider what aspects of mantle-transition zone discontinuity structure would be matched by the predicted discontinuity structure from an Earth-like MCM – particularly the mean depths of the discontinuities, the amplitude of the topography and the shape of its spherical harmonic spectra.

SummaryA joint tomographic inversion for high-resolution P and S wave velocity models of the crust and uppermost mantle in the Middle East is performed using absolute and differential body wave travel times as well as Rayleigh wave dispersions from earthquakes and ambient noises. Checkerboard tests indicate that the models generally have a resolution of 2° x 2° down to a depth of 100 km and reaches 1° x 1° at a depth of 60 km in areas of high-density data coverage such as the Zagros collision zone. The velocity models reveal that the sedimentary layer in the region is nonuniform with a maximum thickness in the Mesopotamian foreland, Persian Gulf, southern Caspian Sea, and eastern Mediterranean Sea (∼10 km), whereas most of the Arabian Shield has no sedimentary cover. The Moho discontinuity vary considerably beneath the Arabian Plate with its shallowest extent at the Red Sea Rift (∼10 km) and its deepest under the Zagros collision zone (∼50 to 55 km). The Arabian Shield and Arabian Platform have a relatively uniform Moho depth of ∼40 km. Widespread low velocity anomalies in the upper mantle are found along the margins of the Arabian Plate and mountain ranges of the Anatolia and Iran plateaus which coincide with the Quaternary volcanism in the region. Extensive low velocity anomalies are observed in the upper mantle underneath the southern and central Red Sea Rift and the Arabian Shield, which may represent partial melt or upwelling hot asthenosphere material from the Afar plume or East African superplume. The southern Red Sea is in an active rifting stage driven by the upwelling of the asthenosphere, whereas the northern Red Sea is in a hybrid mode of active and passive rifting. The Arabian Plate drift toward the northeast is likely the driving force for the passive rifting. In the Zagros collision zone, crustal thickening with low velocity anomalies in the upper and mid crust is observed. This suggests that the present-day tectonic framework of the Zagros collision zone is the result of oceanic subduction of the Neotethyan Plate under the Eurasian Plate and subsequent continental collision of the Arabian Plate with the Eurasian Plate, during which the lower-velocity felsic upper crust of the Arabian Plate was dragged down under the higher-velocity mafic crust of the Eurasian Plate due to slab pull. The subducted slab has a diversified form with a torn-off central portion. The southern portion slopes steeper than its northern counterpart. The subducted Neotethyan slab likely underwent bending and tearing, and it eventually broke off. The remanent slab underplated to the overriding Eurasian Plate to form a thickened crust under the Zagros orogen. This study corroborates previous findings such as there being different modes of spreading in the northern and southern Red Sea rift and the presence of crustal thickening in the Zagros collision zone, and it unveils more details including asthenosphere material migration along the Red Sea rift and complex suture structure in the Zagros collision zone.

SummaryTimely identification of the triggering mechanism behind the observed seismicity in areas with multiple overlapping human activities is an important research topic that can facilitate effective measures to mitigate the seismic hazard. This task is particularly challenging when dealing with delayed operational data, uncertain focal depths, or uneven seismic monitoring coverage. Here, we propose a deep learning (DL) framework to identify which human activity triggered a certain earthquake in near real-time using only seismic waveforms as input. We use an advanced architecture, the compact convolutional transformer (CCT), to extract high-level abstract features from the three-component seismograms and then use an advanced capsule neural network to link the induced seismicity in West Texas with three potential causal factors, i.e., hydraulic fracturing (HF), shallow saltwater disposal (SWDsh), or deep saltwater disposal (SWDdp). The training data was prepared based on an established probabilistic approach that combined physics-based principles with both real and reshuffled injection data to hindcast past seismicity rates. In the end, each activity was assigned a confidence level for association at the 5 km spatial scale. Even though the training data include only 981 events, we obtain over 90% accuracy for all three causal factors for both the single- and multi-station versions of the model.

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 U.S. Department of Agriculture (USDA) is proposing rescinding the 2001 Roadless Area Conservation Rule, which protects about 45 million acres (182,000 square kilometers) of National Forest System lands from road construction, reconstruction, and timber harvests.

Of the land that would be affected by the rescission, more than 95% is in 10 western states: Alaska, Montana, California, Utah, Wyoming, Nevada, Washington, Oregon, New Mexico, and Arizona. The change would not apply to Colorado and Idaho, which have state-specific roadless rules.

Secretary of Agriculture Brooke L. Rollins first announced the USDA’s rescission of the rule on 23 June, prompting negative responses from several environmental, conservation, and native groups.

“The Tongass is more than an ecosystem—it is our home. It is the foundation of our identity, our culture, and our way of life,” said a letter from the Central Council of the Tlingit and Haida Indian Tribes of Alaska to the USDA and the U.S. Forest Service. “We understand the need for sustainable industries and viable resource development in Southeast Alaska. Our communities need opportunities for economic growth, but that growth must be guided by those who call this place home.”

 
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• Secretary Rollins Opens Next Step in the Roadless Rule Rescission
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On 27 August, the USDA released a statement about the agency taking “the next step in the rulemaking process,” noting that the proposal aligned with several recent executive orders, including Executive Order 14192, Unleashing Prosperity Through Deregulation and Executive Order 14153, Unleashing Alaska’s Extraordinary Resource Potential.

“This administration is dedicated to removing burdensome, outdated, one-size-fits-all regulations that not only put people and livelihoods at risk but also stifle economic growth in rural America,” Rollins said in the release.

A notice of intent seeking public comment on the proposal was published in the Federal Register on Friday, 29 August, but a preview of the document became available for public inspection on 28 August. The document suggests that the rule has posed “undue burden on production of the Nation’s timber and identification, development, and use of domestic energy and mineral resources.” Repealing the rule, the document states, would allow for local land managers to make more tailored decisions and would allow for better wildfire suppression.

“This scam is cloaked in efficiency and necessity,” said Nicole Whittington-Evans, senior director of Alaska and Northwest programs at Defenders of Wildlife, in a statement. “But in reality, it will liquidate precious old-growth forest lands critical to Alaska Natives, local communities, tourists and countless wildlife, who all depend on intact habitat for subsistence harvesting, recreation and shelter. Rare and ancient trees will be shipped off at a loss to taxpayers, meaning that Americans will subsidize the destruction of our own natural heritage.”  

The proposal will be open for public comment through 19 September.

–Emily Dieckman, Associate Editor (@emfurd.bsky.social)

29 August 2025: This article was updated with a link to the notice of intent published in the Federal Registrar.

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.

About 71% of Earth's surface is covered by the vast oceans. When winds blow over the sea surface, they transfer energy to the water, creating waves. Some of these waves, under the force of strong winds, break and produce tiny airborne droplets that become sea spray aerosols. This process happens across all oceans and is one of the world's largest sources of aerosols. Despite decades of research, scientists still do not fully understand the impact on the planet's climate, especially how much they contribute to particles that form clouds, known as cloud condensation nuclei.

A research team from the Aerospace Information Research Institute of the Chinese Academy of Sciences has developed a new method for evaluating urban sustainability, leveraging high-resolution data from the SDGSAT-1 satellite, according to a study published in Remote Sensing of Environment.

A team of geoscientists has identified a subtle but powerful force driving mountain building and compression of Earth's crust in Japan and neighboring regions. The so-called same-dip double subduction (SDDS) in nearby oceanic trenches has effects reaching hundreds and thousands of kilometers away from the zone of subduction.

Under high-emission scenarios, the Atlantic meridional overturning circulation (AMOC), a key system of ocean currents that also includes the Gulf Stream, could shut down after the year 2100. This is the conclusion of a new study, with contributions by the Potsdam Institute for Climate Impact Research (PIK). The shutdown would cut the ocean's northward heat supply, causing summer drying and severe winter extremes in northwestern Europe and shifts in tropical rainfall belts.

For decades, the Tijuana River has carried millions of gallons of untreated sewage and industrial waste across the U.S.-Mexico border. The river passes through San Diego's South Bay region before emptying into the ocean, recently leading to more than 1,300 consecutive days of beach closures and water quality concerns.

Clouds are important for Earth's energy balance because they interact with radiation in different ways. On one hand, low clouds reflect incoming solar radiation and thus cool Earth through a property known as albedo. On the other hand, clouds mainly at high altitudes prevent thermal radiation from escaping into space, which has a warming effect. Overall, the cooling effect currently dominates.

A more thorough way to estimate how much the world's boreal-Arctic wetlands and lakes contribute to current and future harmful methane emissions has been developed in part by University of Alberta researchers.

Humanity and the environment's adaptation to climate change is dependent on water, but projecting how water resources will be impacted in the future is difficult.

How Earth's atmosphere transformed from oxygen-poor to oxygen-rich over a span of about two billion years has been revealed by an international team of researchers.

An international team of scientists led by microbiologists Marc Mussmann and Alexander Loy from the University of Vienna has discovered a new microbial metabolism: so-called MISO bacteria "breathe" iron minerals by oxidizing toxic sulfide.

Greenland, despite its name, is largely blanketed in ice. And beneath that white expanse lies a world of hidden lakes. Researchers have now used satellite observations to infer that one such subglacial lake recently burst through the surface of the Greenland Ice Sheet, an unexpected and unprecedented event. By connecting this outburst with changes in the velocity and calving of a nearby glacier, the researchers helped to unravel how subglacial lakes affect ice sheet dynamics. These results were published in Nature Geoscience.

Researchers have known for decades that pools of liquid water exist beneath the Antarctic Ice Sheet, but scientific understanding of subglacial lakes in Greenland is much more nascent. “We first discovered them about 10 years ago,” said Mal McMillan, a polar scientist at Lancaster University and the Centre for Polar Observation and Modelling, both in the United Kingdom.

Subglacial lakes can exert a significant influence on an ice sheet. That’s because they affect how water drains from melting glaciers, a mechanism that in turn causes sea level rise, water freshening, and a host of other processes that affect local and global ecosystems.

McMillan is part of a team that recently studied an unusual subglacial lake beneath the Greenland Ice Sheet. The work was led by Jade Bowling, who was a graduate student of McMillan’s at the time; Bowling is now employed by Natural England.

Old, but Not Forgotten, Data

In the course of mining archival satellite observations of the height of the Greenland Ice Sheet, the team spotted something unusual in a 2014 dataset: An area of roughly 2 square kilometers had dropped in elevation by more than 80 meters (260 feet) between two satellite passes just 10 days apart. That deflation reflected something going on deep beneath the surface of the ice, the researchers surmised.

A subglacial lake that previously was situated at the interface between the ice and the underlying bedrock must have drained, said McMillan, leaving the ice above it hanging unsupported until it tumbled down. The team used the volume of the depression to estimate that roughly 90 million cubic meters (more than 3.1 billion cubic feet) of water had drained from the lake between subsequent satellite observations, making the event one of Greenland’s biggest subglacial floods in recorded history.

“We haven’t seen this before.”

Subglacial lakes routinely grow and shrink, however, so that observation by itself wasn’t surprising. What was truly unexpected lay nearby.

“We also saw an appearance, about a kilometer downstream, of a huge area of fractures and crevassing,” McMillan said. And beyond that lay 6 square kilometers (2.3 square miles)—an area roughly the size of lower Manhattan—that was unusually smooth.

The researchers concluded that after the subglacial lake drained, its waters likely encountered ice frozen to the underlying bedrock and were forced upward and through the surface of the ice. The water then flowed across the Greenland Ice Sheet before reentering the ice several kilometers downstream, leaving behind the polished, 6-square-kilometer expanse.

“This was unexpected,” said McMillan. “We haven’t seen this before.”

A Major Calving, a Slowing Glacier

It’s most likely that the floodwater traveled under northern Greenland’s Harder Glacier before finally flowing into the ocean.

Within the same 10-day period, Harder Glacier experienced its seventh-largest calving event in the past 3 decades. It’s impossible to know whether there’s a direct link between the subglacial lake draining and the calving, but it’s suggestive, said McMillan. “The calving event that happened at the same point is consistent with lots of water flooding out” from the glacier.

Using data from several Earth-observing satellites, scientists discovered that a huge subglacial flood beneath the Greenland Ice Sheet occurred with such force that it fractured the ice sheet, resulting in a vast quantity of meltwater bursting upward through the ice surface. Credit: ESA/CPOM/Planetary Visions

“It’s like you riding on a waterslide versus a rockslide. You’re going to slide a lot faster on the waterslide.”

The team also found that Harder Glacier rapidly decelerated—3 times more quickly than normal—in 2014. That’s perhaps because the influx of water released by the draining lake carved channels in the ice that acted as conduits for subsequent meltwater, the team suggested. “When you have normal melting, it can just drain through these channels,” said McMillan. Less water in and around the glacier means less lubrication. “That’s potentially why the glacier slowed down.”

That reasoning makes sense, said Winnie Chu, a polar geophysicist at the Georgia Institute of Technology in Atlanta who was not involved in the research. “It’s like you riding on a waterslide versus a rockslide. You’re going to slide a lot faster on the waterslide.”

Just a One-Off?

In the future, McMillan and his colleagues hope to pinpoint similar events. “We don’t have a good understanding currently of whether it was a one-off,” he said.

Getting access to higher temporal resolution data will be important, McMillan added, because such observations would help researchers understand just how rapidly subglacial lakes are draining. Right now, it’s unclear whether this event occurred over the course of hours or days, because the satellite observations were separated by 10 days, McMillan said.

It’s also critical to dig into the mechanics of why the meltwater traveled vertically upward and ultimately made it to the surface of the ice sheet, Chu said. The mechanism that this paper is talking about is novel and not well reproduced in models, she added. “They need to explain a lot more about the physical mechanism.”

But something this investigation clearly shows is the value of digging through old datasets, said Chu. “They did a really good job combining tons and tons of observational data.”

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2025), A burst of subglacial water cracked the Greenland Ice Sheet, Eos, 106, https://doi.org/10.1029/2025EO250317. Published on 28 August 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.

Micrometeorites, unlike their larger brethren, rarely get a spotlight at museums. But there’s plenty to learn from these extraterrestrial particles, despite the largest of them measuring just millimeters across.

Nearly 50 tons of extraterrestrial material fall on Earth every day, and the majority of that cosmic detritus is minuscule. Micrometeorites are, by definition, smaller than 2 millimeters in diameter, and they’re ubiquitous, said Fabian Zahnow, an isotope geochemist at Ruhr-Universität Bochum in Germany. “You can basically find them everywhere.”

Researchers recently analyzed fossilized micrometeorites that fell to Earth millions of years ago. They extracted whiffs of atmospheric oxygen incorporated into the particles and showed that carbon dioxide (CO2) levels during the Miocene and Cretaceous did not differ wildly from modern-day values. The results were published in Communications Earth and Environment.

Extraterrestrial Needles in Rocky Haystacks

Newly fallen micrometeorites can be swept from rooftops and dredged from the bottoms of lakes.

Zahnow and his collaborators, however, opted to turn back the clock: The team analyzed a cadre of micrometeorites that fell to Earth millions of years ago and have since been fossilized. The team sifted through more than a hundred kilograms of sedimentary rocks, mostly unearthed in Europe, to discover 92 micrometeorites rich in iron. They added eight other iron-dominated micrometeorites from personal collections to bring their sample to 100 specimens.

Metal-rich micrometeorites such as these are special, said Zahnow, because they function like atmospheric time capsules. As they hurtle through the upper atmosphere on their way to Earth, they melt and oxidize, meaning that atmospheric oxygen gets incorporated into their otherwise oxygen-free makeup.

“When we extract them from the rock record, we have our oxygen, in the best case, purely from the Earth’s atmosphere,” said Zahnow.

Ancient Carbon Dioxide Levels

And that oxygen holds secrets about the past. It turns out that atmospheric oxygen isotope ratios—that is, the relative concentrations of the three isotopes of oxygen, 16O, 17O, and 18O—correlate with the amount of photosynthesis occurring and how much CO2 is present at the time. That fact, paired with model simulations of ancient photosynthesis, allowed Zahnow and his colleagues to infer long-ago atmospheric CO2 concentrations.

“The story of the atmosphere is the story of life on Earth.”

Reconstructing Earth’s atmosphere as it was millions of years ago is important because atmospheric gases affect our planet so fundamentally, said Matt Genge, a planetary scientist at Imperial College London not involved in the work. “The story of the atmosphere is the story of life on Earth.”

But Zahnow and his collaborators first had to make sure the oxygen in their micrometeorites hadn’t been contaminated. Terrestrial water, with its own unique oxygen isotope ratios, can seep into micrometeorites that would otherwise reflect atmospheric oxygen isotope ratios from long ago. That’s a common problem, said Zahnow, given the ubiquity of water on Earth. “There’s always some water present.”

The team found that the presence of manganese in their micrometeorites was a tip-off that contamination had occurred. “Extraterrestrial metal has basically no manganese,” said Zahnow. “Manganese is really a tracer for alteration.”

Unfortunately, the vast majority of the researchers’ micrometeorites contained measurable quantities of manganese. In the end, Zahnow and his collaborators deemed that only four of their micrometeorites were uncontaminated.

Those micrometeorites, which fell to Earth during the Miocene (9 million years ago) and the Late Cretaceous (87 million years ago), suggested that CO2 levels during those time periods were, on average, roughly 250–300 parts per million. That’s a bit lower than modern-day levels, which hover around 420 parts per million.

“What we really hoped for was to get pristine micrometeorites from periods where the reconstructions say really high concentrations.”

The team’s findings are consistent with values suggested previously, said Genge, but unfortunately, the team’s numbers just aren’t precise enough to conclude anything meaningful. “You have a really huge uncertainty,” he said.

The team’s methods are solid, however, said Genge, and the researchers made a valiant effort to measure what are truly faint whiffs of ancient oxygen. “It’s a brave attempt.”

In the future, it would be valuable to collect a larger number of pristine micrometeorites dating to time periods when model reconstructions suggest anomalously high CO2 levels, said Zahnow. “What we really hoped for was to get pristine micrometeorites from periods where the reconstructions say really high concentrations.”

Confirming, with data, whether such time periods, such as the Triassic, truly had off-the-charts CO2 levels would be valuable for understanding how life on Earth responded to such an abundance of CO2.

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2025), Fossilized micrometeorites record ancient CO2 levels, Eos, 106, https://doi.org/10.1029/2025EO250319. Published on 28 August 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.