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Scientists at the University of Melbourne have uncovered for the first time how Australia's iconic Twelve Apostles were formed, finding tectonic plate movements over millions of years lifted and tilted the giant structures out of the sea.

This story was produced by Grist and the Food & Environment Reporting Network, a nonprofit news organization. Sign up for Grist’s weekly newsletter here.

Will Runion’s 736-acre cattle and hay farm is tucked into a horseshoe bend of the Nolichucky River in northeast Tennessee. On the morning of Friday, September 27, 2024, he was in the middle of two big projects: building a riverfront campground on his land to bring in tourists and income, and cutting the last of the season’s hay. Hurricane Helene had been arcing up from Florida toward the Appalachian Mountains, carrying heavy rain, and the river was high. Even though the banks seemed to be holding, he decided to move some of his cows and equipment to higher ground.

But the river kept rising. At about 11 a.m., the brown water topped its banks. He and his fiancée, his son-in-law’s parents, and neighbors scrambled to salvage what farm equipment they could, but they were nearly trapped when the quickly expanding river flowed into a low-lying area behind where they were working, cutting them off from dry land.

By afternoon, the river had swollen to some 1,200 feet wide—nearly 10 times its usual size. It “looked just like a lake,” Runion said. Trees snapped in the swift current and neighbors’ barns, roofs, hay bales, and household debris swirled by. The water swallowed Runion’s hay equipment and sent the little white house he’d planned to use as the new campground’s office sailing across a field.

At around 8 p.m., the Nolichucky finally crested and started to recede. Runion found a third of his fields covered in debris, dead fish, and tomatoes from upstream vegetable growers. The flood had gouged two holes the size of football fields in his hay pastures, down to a depth of 12 feet. Other sections of the farm were buried in up to 8 feet of sand or silt.

Flooding from Hurricane Helene brought massive damage to Will Runion’s farm, eroding the land in some places and washing up feet of sand on agricultural fields in other sections. Courtesy of Bryan LeBarre, via Grist

Helene dropped up to 30 inches of rain on southern Appalachia, causing historic flooding and landslides in parts of North Carolina, South Carolina, Tennessee, Georgia, Kentucky, and Virginia—a largely rural region where agriculture is a vital economic driver and cultural cornerstone. The mountains make it hard to spread out here, so farms tend to be small, and many growers use flood-prone bottomland because it is flat and fertile. But floods of this magnitude hadn’t hit here in generations. In North Carolina alone, Helene caused an estimated $4.9 billion in damage to the state’s agriculture sector. In Tennessee, agricultural losses were estimated at $1.3 billion. Thousands of farmers lost crops, tools, machinery, barns, buildings, animals, and fences.

“When you see 4 feet of sandy soils on top of your topsoil, you know that’s going to be a challenge. That was overwhelming.”

More than a year later, growers are also contending with the loss of something more vital, and more difficult to replace: their soil.

Runion knew immediately that his livelihood was ravaged. Without good soil, a farmer can’t farm. “When you see 4 feet of sandy soils on top of your topsoil, you know that’s going to be a challenge,” he said. “That was overwhelming.”

He sent drone footage of the damage to Forbes Walker, an environmental soil specialist with University of Tennessee Extension. “How do you fix this?” he asked.

“I don’t know,” Walker recalled thinking when he got Runion’s email. “How do we fix this?”

Over millennia, floods helped build the fertile land that farmers depend on. But today, climate change is driving more powerful and unpredictable storms. One study found that rainfall associated with Helene was 10 percent heavier due to man-made climate change. Research by the U.S. National Science Foundation suggests that what scientists call “100-year storms” will become three times more likely, and 20 percent more severe, over the next 50 years. What’s more, there’s little solid information about what happens to soil during a flood, or what to do when a farm’s soil is eroded or covered with material from elsewhere—its nutrients washed away and microbial communities disrupted. It’s a blind spot that is becoming more of a liability as storms like Helene become more common.

“None of us had ever seen anything like this before or responded to an emergency like that,” said Stephanie Kulesza, a nutrient and soil scientist at North Carolina State University. “And so we weren’t really prepared for recommendations to provide to producers.”

Soil can take thousands of years to form. Rock is weathered and slowly dissolves into smaller and smaller pieces. As dead leaves, animals, trees, and other plants decompose, they add organic matter and nutrients to the rock. Microorganisms establish themselves in the mix, driving nutrient cycling, aiding with decomposition, and stimulating plant growth; then worms and bugs, like beetles and ants, burrow in the mixture, aerating it. For soils to work well for agriculture, they need the right structure—airy enough to allow water to enter and move through, but not too quickly or too slowly—and sufficient biological and chemical richness, including nutrients like nitrogen, phosphorous, and potassium, to nourish crops.

Farmers use synthetic or natural fertilizers to ensure their soil has enough nutrients. They can also introduce practices like no-till—farming without plowing up the ground—to maintain the physical properties of their dirt. Topsoil, the rich, uppermost layer with the most available nutrients for crops, tends to make up less than a foot of the entire soil profile, but it’s crucial for agriculture.

Soil scientist Forbes Walker visits Will Runion’s farm in 2025, examining the deep sandy deposits left behind by Hurricane Helene. Credit: Raffe Lazarian/University of Tennessee Institute of Agriculture via Grist

Helene’s floodwaters either washed away significant topsoil or deposited new sediment on top of it on thousands of farms. Some, including one of Runion’s neighbors, saw their fields stripped down to bedrock, or river rock. Runion and others woke to pastures blanketed by feet of sand or stone.

When topsoil is washed away, the necessary nutrients for growing go with it. And when topsoil is covered with sand, farmers can’t get to it. Both scenarios can significantly alter the land’s usability. Topsoil can take decades or centuries to develop, and sand lacks both organic matter and the physical structure to hold water and nutrients. “These aren’t soils yet,” said Kulesza of what Helene left on Runion’s and other farmers’ land. “They are in their infancy now. The clock has been reset.”

Runion had cared for his soils, working to eliminate weeds, adding fertilizer to keep nutrient levels ideal, and lime to control pH. “They were our way of life,” Runion said. “They were our income.”

After the storm, from October to April, he removed debris, bulldozed sand off his fields to get closer to the topsoil, filled holes, and graded uneven land. Crews from the Federal Emergency Management Agency removed and shredded downed trees. He applied for government relief and received close to $1 million in state and federal aid. Runion said he could have easily used all of that money replacing equipment and paying for cleanup labor, fertilizer, and fuel, but he’s trying to stretch the money as much as possible.

By June, it was time to mow the fields that hadn’t flooded. He managed to put up enough bales of hay to feed his herd of 125 cattle, but not enough to sell. In a normal year, hay sales made up about a third of the farm’s income. With months of work behind him and his flooded land still too sandy and generally depleted, he realized the recovery would be a slog.

Runion returned to work on the campground, which he hoped would diversify the family’s earnings. The longer-term plan included a music venue and some hiking trails, and to host weddings and corporate events. After the storm, finishing it took on new urgency. He chose a new spot, about 450 feet upland from the river, and began clearing enough land for 45 camping sites.

One environmental soil specialist described the academic literature on flood-damaged soils as “thin.”

Runion also prepared a parcel of land for Walker, the extension soil specialist, to run tests that could guide his recovery. Last November, soon after the one-year anniversary of Helene, Walker showed me around Runion’s farm.

Working with students, Walker established four experiments over about 300 test plots. He’s looking at how different soil amendments—hay, wood chips, poultry litter, and a charcoal called biochar, to help the soil hold water and fertilizer; and Triple 19, a common plant food with equal parts nitrogen, phosphorous, and potassium—affect the growth of wheat and fescue grasses.

When I visited, some of the plots remained mostly bare while, in others, tufts of green had sprouted. “We actually got some stuff to grow,” Walker said.

He described the academic literature on flood-damaged soils as “thin.” While some research and case studies exist on how agricultural soil recovers after a flood, there are few systematic investigations like the one Walker is conducting—on what works, and what does not—particularly in Appalachia, where floods of this magnitude have been historically rare.

When so-called atmospheric rivers spawned devastating floods in the Pacific Northwest and southwestern British Columbia in 2021, Aimé Messiga, a Canadian soil research scientist at the Agassiz Research and Development Centre, found a similar “scarcity of data.” He conducted a detailed review of the existing research and concluded that there was limited long-term monitoring, little understanding of how floods affect nutrients and microorganism communities in the soil, and uncertainties about what the actual impacts of floods on agriculture and crops are. Complicating everything is the variability between different farms, soils, and crops.

“You need decades of accumulated data in order to be able to predict what will happen. We don’t have those data.”

“You need decades of accumulated data in order to be able to predict what will happen,” Messiga said. “We don’t have those data.”

Today, some researchers are attempting to replicate flood conditions in labs to better understand, but field work is rare, Messiga said. There’s little money for it—and in the U.S., the Trump administration has cut funding for climate-related research. In addition, “many among us still look at these events as random,” Messiga said. “They’re not random. They will keep occurring.”

Since 1980, 45 flooding events have caused damages over $1 billion each in the U.S., with more than half of those occurring in the past 15 years. In 2024, flooding in the upper Midwest drowned crops. Repeat events in central California damaged agricultural operations from winter 2022 to spring 2023. Flooding along the Mississippi River in 2019 reduced crop planting by millions of acres. There also have been numerous smaller or more localized floods. One study found nearly 75,000 flash floods in the contiguous U.S. from 1996 to 2017, with increasing frequency in the past 22 years. Flooding frequency and strength is predicted to rise in the years to come due to climate change—a warmer atmosphere holds more moisture and leads to stronger rain events—and poor land-use management.

Scientists are also starting to study a new type of event, called “weather whiplash,” when sudden changes occur from one extreme to another, amplifying the effects of the disaster. In Texas in 2025, a flood came after prolonged drought, causing widespread destruction.

For farmers, the effects of flooding on soil may linger for years after the disaster. In 2011, the Missouri River flooded states in the Upper Midwest, including thousands of acres of farmland. Fields were swamped for months with up to 20 feet of water. When the water finally receded, those fields were covered with anywhere from 2 to 20 feet of sand; other fields had washed out holes up to 70 feet deep. It looked like the surface of the moon, said John Wilson, a now-retired educator and agricultural expert who served Burt County, Nebraska, which was particularly hard-hit. “It was just bare soil,” he said. “There was no crop residue whatsoever.”

Wilson led teams that sampled the soil and helped farmers build back. He found that levels of nitrogen and organic matter were low in flooded soils, and fertility suffered when farmers planted their crops. Over about five years, fertility generally improved, but not everywhere. “If you went out today and did a yield map, you could still tell exactly where the erosion was because those areas are not as productive,” Wilson said.

Yield is money for farmers, who already navigate thin margins and, often, years without any profit at all. North Carolina’s strategic plan for agriculture recently enumerated just how thin: Of the state’s “42,500 farms, only 8,000 produce annual gross sales that exceed $100,000 annually. The overwhelming majority … some 23,400, gross less than $10,000 in sales, with only around 40 percent of the farms in the state having a positive net income in 2022.”

As floods increasingly wreck farmland, more researchers are starting to focus on understanding the effects of the floods and how to address them. Most of that work is happening in Asia, Messiga said. But a study in coastal North Carolina, where hurricanes regularly land, found that after a storm there was less organic matter in the soil, including carbon, and a disruption of microbial activity and nutrient cycling. The ground also absorbed water less readily.

Coastal flooding is also driving saltwater into the soil of farmland, making it more saline and unable to sustain crops. A North Carolina State University team has been developing test kits for farmers to sample the salinity of their soils, as well as a set of recommendations for keeping their soil viable. Such local work is important because soils vary greatly from place to place, and findings are not often easily transferable.

Nicole DelCogliano’s farm near Asheville, North Carolina, was wiped out almost entirely by floods from Hurricane Helene in 2024. Courtesy of Nicole DelCogliano via Grist

For now, in the wake of Helene, farmers are relying largely on trial and error to build back what was lost. Nicole DelCogliano has been farming vegetables, flowers, and livestock with her husband on 50 acres on the South Toe River, near Asheville, North Carolina, for 25 years. Helene washed away her barn, tractor, and other infrastructure. Of her 6 acres of vegetable fields, one was covered with several feet of sand, another got a foot, and a third field suffered extensive erosion.

“Our entire operation was wiped out, essentially,” she said.

“It’s not something that can be fixed overnight. This is a long process.”

With the help of some friends with tractors, DelCogliano cleared her main field and spread compost and lime on everything. “There was a mix of guidance about what you should do, like should you disturb the soil, should you not?” she said. “At an instinctual level, we just felt like we got to get the soil covered, we got to get something in the ground.” They sowed rye, a dependable cool season grass, as a cover crop, to protect the soil from erosion and add nutrients.

Karen Blaedow, an agricultural educator in Henderson County, North Carolina, said farmers should expect to put in at least three years of cover cropping before they see results in their soil. “It’s not something that can be fixed overnight,” she said. “This is a long process.”

In the spring following the flood, DelCogliano spread various amendments on her least-damaged field, including compost, lime, biochar, and blood and bone meal, which provide nitrogen and phosphorus, respectively. After all that, she and her husband seeded crops.

Their new vegetables came in about two weeks later than normal, but the season was more productive than ever, even though they grew on just 4 instead of 6 acres—“which is pretty amazing,” she said. “When we first started harvesting crops [after Helene], we didn’t yet have power at the farm. I had to dig one of our sinks out of a bank and bleach it and clean it and drag it up to the new barn—that we barely got a roof on—to wash and pack for that first [farmers] market.”

She doesn’t really know what made the year so productive. They planted more intensively to account for the smaller acreage and were able to harness their years of expertise to restart their operation basically from scratch. She also attributes the relative health of her soil to years of organic practices. “We’re dirt farmers,” she said. “Our primary job is to tend the dirt. Because that’s the basis of everything.”

Some farmers who’ve seen good harvests may have gotten a little lucky. Rather than sand, floods dumped silt. Even Runion got silt deposits in one section of his farm. Unlike the sand, the silty layers carry nutrients and create a positive growing environment. “We have a producer we work with and he said it’s the most fertile soil that he’s had in decades,” said Emine Fidan, a biosystems engineering and soil science researcher at the University of Tennessee, who’s also working on Runion’s farm. “And he said it grew the sweetest corn he’s ever had. It was growing just beautifully.”

Runion didn’t plant anything until this past fall. He prepared about 65 acres of the 220 that were underwater. It was slow going; he used a disking machine to till his land but had to stop often to clear sticks and trash and to grade out low spots. He mixed in mulch and planted oats, wheat, and fescue. Walker drove me past one of the fields and it still looked sandy, the grasses just a pale green shadow on the tan land. Runion said the greenery was “struggling to have any vigor about it.” He won’t know for sure how well or poorly the grasses do until spring, their peak growing season.

He considered planting more acreage but decided to wait and see what he learned from Walker’s trials. “It’s a process, and the knowledge we’re gaining there will help on the whole rest of it, too,” Runion said.

This spring, Walker’s team will measure the biomass in each plot as well as the quality of the crop, including how much protein it has and its digestibility. They’ll also be evaluating the soil itself, including its ability to hold water, to determine if any of the treatments improved the structure of the sandy dirt.

One farmer thinks the hay he’ll get in the coming years will be lower-yielding, lower-quality, and will cost more to produce due to the extra prep time, new seeds, and fertilizers.

Preliminary results suggest that, in plots where they put down mulch, the grasses are growing better than in plots with other amendments. The woody debris is reducing erosion and seeds are germinating well and standing up in the rough matrix. Spreading this kind of mulch isn’t an obvious solution, Walker said: Wood chips are a carbon-rich material, but as they break down in the soil they consume nitrogen, which can lead to a deficiency for the crops. But this mulch had sat in piles and started to decompose before it was applied to Runion’s fields, which made it less likely to cause these problems.

Runion had asked FEMA to leave the piles of wood chips on his farm rather than remove them like they normally would. Walker is looking for solutions to the soil problem that not only work but are also accessible. Have a mountain of mulch? Put it to work. Have nearby chicken houses? Maybe their nitrogen-rich manure can help revive flooded fields. His hope is that his team’s research can provide some guidance to farmers who find themselves in similar situations in the future. “I think it will have broad implications for a number of different crops,” including vegetables, Walker said.

Meanwhile, Runion is coming to terms with his situation. He thinks the hay he’ll get in the coming years will be lower-yielding, lower-quality, and will cost more to produce due to the extra prep time, new seeds, and fertilizers. He used to sell a lot of square bales, which tend to contain high-quality grasses and fetch a higher price, but he doesn’t expect to be doing that for a while. He’d initially hoped to have his land back in shape in a year or two. “Now it’s a four- to five-year [plan], I think,” Runion said. “It has been frustrating, and exhausting, too.”

He’s still optimistic, though. On my visit, I watched him grade out the new campground in a large dump truck. Freshly exposed red soil lay open to the sky. He thinks he can get the campground open by late summer or early fall. Over time, he hopes, it will be a more lucrative, and more sustainable, source of income. “The farm is really beautiful,” Runion said. “It still has a lot to offer.”

—Irina Zhorov, Grist

This article originally appeared in Grist at https://grist.org/extreme-weather/hurricane-helene-ravaged-farmers-topsoil-theyre-still-fighting-to-build-it-back/.

Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Earth Surface

Turbidity currents are underwater currents that transport sediment on the sea floor. They were first observed in the late 1800s in Lake Geneva, Switzerland. The cable break following the 1929 Grand Banks earthquake offshore Canada revealed how massive and destructive these fluxes can be.

Turbidity currents move downslope because they have a higher density than the surrounding water due to the presence of sediment in suspension. It is critical to keep in mind that suspended sediment concentration in these flows is low, meaning that the fluid is Newtonian and the flow is turbulent.

Notwithstanding recent advances in field monitoring, measuring turbidity current thickness, velocity, suspended sediment concentration, and grain size distribution remains difficult not only for the high-water depths and the destructive nature of some events, but also because these flows are often infrequent. Laboratory experiments and mathematical modeling have been used extensively to understand nature and some aspects of these flows, but questions remain on, for example, how turbidity currents interact with ocean waves, if they do.

Daniller-Verghese et al. [2026] performed laboratory experiments to determine if and how turbidity currents interact with ocean gravity waves. Experimental flows were released in an 11-meter-long, 1.2-meter-deep, and 0.61-meter-wide flume in the Experimental Sedimentation Laboratory of the Jackson School of Geoscience at the University of Texas. A motored wave maker was installed at the downstream end of the facility to generate the wave field. During the experiments, detailed velocity measurements were conducted to characterize the flow field and the fine details of the turbulent fluctuations. At the end of each experiment, high-resolution measurements of changes in bed elevations allowed the quantification of the net depositional fluxes.

The results show that, in presence of a superimposed wave field, the center of deposition volume shifted downstream compared to experiments conducted with the same inflow but in absence of waves. In addition, velocity measurements indicate that the wave signal is stronger in presence of turbidity currents compared to the “clear water” case. In other words, current velocity was larger when waves were present, enhancing downslope sediment transport and causing the observed downstream shift of the center of deposition.

Although the physical mechanism responsible for the observed increase of sediment transport rates in presence of a superimposed wave field still needs to be resolved, these results provide novel insight for the interpretation of storm and turbidity current deposits in the rock record. They also highlight the importance of considering wave-turbidity current interactions to constrain sediment budgets on continental shelves, which are essential to preserve and manage coastlines worldwide.

Citation: Daniller-Varghese, M., Smith, E., Mohrig, D., & Myrow, P. (2026). Wave-signal entrainment into combined flows: Consequences for sediment transport, signal dislocation, and turbulence. Journal of Geophysical Research: Earth Surface, 131, e2025JF008497. https://doi.org/10.1029/2025JF008497

—Enrica Viparelli, Associate Editor, JGR: Earth Surface

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.

Eastern Africa's Turkana Rift is both a hotbed for fossil discoveries of our earliest ancestors and a literal hotbed of volcanic activity caused by shifting tectonic plates. Now researchers have found that Earth's underlying crust in the region has been significantly thinned, presaging Africa's eventual breakup—and with that finding, the researchers offer a new perspective on how Turkana's world-famous fossil record of human evolution came to be. The findings are published in Nature Communications.

SummaryGeodetic measurements of ground deformation are crucial to identifying and interpreting geophysical processes. We develop a method to fuse data streams from multiple geodetic techniques into a single, three-component deformation field with quantified uncertainties, and without invoking a geophysical model. The fusion is formulated as a semi-parametric latent factor model: a linear mapping ties each observation to the underlying 3-D displacement, while the displacement components are represented nonparametrically with multi-output Gaussian process priors. To achieve practical performance at regional scale, we deploy two complementary sparse GP engines: an Informative Vector Machine (IVM) that selects a small, most-informative active set for fast subset-of-data inference, and a Sparse Variational GP (SVGP) that summarizes the full dataset with inducing points and optimizes a global variational bound. Together, these reduce the scaling of the computation to near-linear in data size and cubic only in the active/inducing set, enabling the potential of fusion of dense geodetic data while maintaining rigorous uncertainty quantification. We demonstrate the approach on coseismic deformation from the 2020 Sparta, NC, USA and 2016 Meinong, Taiwan earthquakes, fusing interferometric synthetic aperture radar (InSAR) with either light detection and ranging (LiDAR) or global navigation satellite system (GNSS) data, respectively. The fused solutions show marked improvements in the precision and coherence of the resolved deformation field and deliver robust, spatially explicit uncertainty estimates. The methodology is readily extensible to time-varying observations to produce four-dimensional (space-time) deformation fields, offering a scalable path to richer characterization of transient geophysical phenomena.

SummaryThe 2019 Mw 6.4 Durrës earthquake in Albania caused severe loss of life and economic damage, highlighting the seismic hazard along the Adriatic–European plate boundary. This study provides the first high-resolution analysis of the aftershock sequence based on data from a dense local seismic network deployed three weeks after the mainshock. Using machine-learning detection and phase-picking tools, we identified 19 152 aftershocks (Ml − 1.8 to 4.6; Mc ≈ 1) over a nine-month period. Based on a newly derived 1D velocity model with station corrections, accounting for large vertical and lateral velocity variations, we relocated the events applying cross-correlation based differential travel times and the double-difference algorithm. The refined seismicity images clearly reveal several sub-parallel ∼30° NE-dipping blind fault structures; the most prominent one, between 12 and 18 km depth, probably hosted the Durrës mainshock. The blind thrust faults lie beneath thick sediments and cut through a carbonate platform and into the Adriatic basement, indicating thick-skinned deformation. Our observations may be interpreted as incipient large-scale slicing and underplating of subducted Adriatic crust. Additional shallow seismicity within a duplex structure in the hanging wall points is relevant for seismic hazard, as even a relatively moderate earthquake occurring close to the surface could cause significant damage.

SummarySeismograms contain a variety of signals in addition to direct waves. The local later phase in the S coda (LPS; strongly reflected or scattered S-waves by subsurface heterogeneities when the hypocentre, station, and the origin of the later phase are located relatively close to each other) is useful for investigating fine-scale subsurface heterogeneities such as significant velocity contrasts and localized scatterers. With the development of dense seismic observation networks, accurate and rapid automatic processing techniques for large numbers of seismograms have become important. The introduction of deep learning techniques enables us to automate the processing of seismograms, such as phase detection and arrival time picking of direct waves with high quality and speed. To utilise the information on LPSs contained in large volumes of seismic waveform data, we developed the LPS-detector, a convolutional neural network-based automatic LPS detection model. We trained the LPS-detector using single-station data from the Moriyoshi volcanic area in northeastern Japan, which is known for observing distinct LPSs. We create an original training dataset with 5 000 earthquakes in this area. The training dataset was separated into the training (3 200), validation (800), and test (1 000) subsets. The LPS-detector yielded a 0.910 area under the curve (AUC) of the receiver operating characteristic (ROC) curve and 0.966 AUC of the precision-recall (PR) curve. These scores indicate good performance for automatic LPS detection, which is comparable to that of manual detection. Additionally, we confirmed that the LPS-detector could detect LPSs at other stations if the waveform characteristics were similar to those of the training subset. The large volume of the LPS catalogue obtained by the LPS-detector provides a new insight into the LPS origin in the Moriyoshi volcanic area. The LPS-detector detected 3 951 new LPSs outside of the training period. Combined with manual detection, 7 599 LPSs were detected in this area. Based on the comprehensive LPS catalogue, we found that the origin of LPSs in this area lies just beneath the earthquake swarm and is inclined at approximately 12° with a south-westward dip. These results indicate that the LPS-detector enables us to extract LPS information from seismogram big data and explore fine-scale subsurface structures.

SummaryThe British Palaeogene Igneous Province records the palaeomagnetic field at a time when it had returned to a reversing state following the Cretaceous Normal Superchron. Whilst the province is well studied for palaeomagnetic directions, palaeointensity results remain scarce. New palaeointensity and palaeomagnetic directional results are presented from a Palaeocene basaltic dyke swarm on the Sleat Peninsula, Skye (NW Scotland). The mean palaeomagnetic direction from 24 dykes has declination 356.7° and inclination 60.0°. The corresponding palaeopole lies at 75.2°N, 181.8°E with associated 95 per cent confidence interval, A95, of 6.6° which is close to, but distinguishable from, previous results from this swarm. The angular dispersion of virtual geomagnetic poles (VGPs), SB, was 17.9 ± 3.2°, consistent with stationary VGP dispersion throughout the Palaeogene. Three experimental palaeointensity methods were attempted: Shaw Double Heating Technique, thermal Thellier, and microwave Thellier. Palaeointensity experiments were successful from two dykes giving results of 15.8 ± 2.3 μT and 12.0 ± 3.4 μT which correspond to virtual dipole moments of 27 ± 4 ZAm2 and 21 ± 6 ZAm2. These are notably weaker than the long-term average and the recent field. Additionally, we present proof-of-concept of a novel method for estimating palaeointensity. The preliminary method was applied to results from the thermal Thellier experiments and is based on reproducing non-ideal Arai plot behaviour using a phenomenological model of thermal remanent magnetisation. This inversion highlighted laboratory field orientation as a major control on Arai plot shape with antiparallel fields predicted and observed to cause major distortions. It produced similar palaeointensity results to the conventional approach but derived from significantly more specimens.

Summary3D magnetotelluric (MT) inversion is a powerful tool for imaging the Earth’s electrical structure, yet its computational demands remain a major challenge, particularly when simulating responses across broad frequency bands. Conventional inversion schemes rely on a unified mesh for forward simulation at all frequencies, which inflates the number of model parameters and greatly extends runtime. To overcome these limitations, we present a finite-volume-based frequency-domain survey decomposition (FVFSD) method that adaptively constructs forward simulation meshes according to the skin depth of each frequency while maintaining a fixed horizontal discretization. This design decouples forward simulation meshes from the inversion mesh, striking a balance between accuracy and efficiency. To further improve the treatment of resistivity contrasts, an equivalent circuit scheme is employed to compute effective conductivities within control volumes, outperforming conventional volume-weighted averaging. We validate the proposed method through comprehensive numerical experiments, including synthetic benchmarks and real-world case studies from the Akebasitao region (China) and the Southern African MT experiment. Results demonstrate that FVFSD achieves accuracy comparable to standard finite-difference forward simulations, while significantly reducing computational time. In large-scale MT inversions, this acceleration directly translates into faster convergence and more efficient recovery of lithospheric-scale resistivity structures. The method is fully compatible with existing inversion algorithms and solvers, making it straightforward to integrate into standard workflows. Overall, FVFSD provides a scalable and accurate strategy for advancing 3D MT inversion, with clear implications for lithospheric studies, resource exploration, and tectonic investigations.

Too much stress can make even a rock crack. But before rocks reach their breaking point, they "sigh" a chemical warning by releasing nuclides, a type of atom defined by the number of neutrons as well as protons in the nucleus. Scientists have studied these naturally occurring geochemical emissions for more than half a century, but struggled to link nuclide release to the timing of rock breakage. Now, an international team of scientists from universities in China (led by Xin Luo at Hong Kong University and Yifeng Chen at Wuhan University) and the United States (led by Michael Manga at the University of California, Berkeley) has cracked that mystery, by creating a model to connect nuclide signal fluctuations to progressive changes in rock structure that lead to critical failure.

For more than 100,000 years, the Methana volcano in Greece appeared dormant. No lava, no explosions, no ash clouds. It appeared extinct, like many other volcanoes today. An international research team led by ETH Zurich has reconstructed a detailed, long-term history of the Methana volcano. Their work is published in the journal Science Advances, and their conclusion is striking: While Methana appeared silent at the surface, enormous amounts of magma were steadily accumulating deep within its magma chambers.

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

After more than half a century of Earth Days, one planetary challenge—climate change—threatens our planet more than ever.

In 1970, the year Sen. Gaylord Nelson (D-Wisc.) organized the first Earth Day events, the annual average concentration of carbon dioxide in the atmosphere was 326 parts per million. In 2025, it was 31% higher, at 427 parts per million. 

“It may sound small, but it’s reshaping daily life.”

Changes in average annual temperatures in U.S. cities and states show the powerful effects of this increase in heat-trapping carbon dioxide. A new analysis, published today by climate research and communications nonprofit Climate Central, found that since 1970, all 50 states and 99% of major U.S. cities have warmed, with an average city-level increase of 1.6°C (2.9°F).

“It may sound small, but it’s reshaping daily life,” Shel Winkley, a meteorologist at Climate Central, said in a video released alongside the report. 

On average, the 49 U.S. states analyzed in the report have warmed by 1.7°C (3.0°F) since 1970. The six states that have warmed the fastest since the first Earth Day are Alaska with a 2.4°C (4.4°F) increase, New Jersey and New Mexico with a 2.1°C (3.7°F) increase, and Delaware, Massachusetts, and Vermont with a 2°C (3.6°F). Trends for Hawaii, which were analyzed separately and not included in the national average, also showed statewide warming.

In 2025, the United States was on average 1.4°C (2.6°F) warmer than the 20th century average. The Paris Agreement, a legally binding global treaty, sets a goal to limit warming to 1.5°C (2.7°F) above preindustrial levels, though some scientists expect that the world has already entered the period of time during which this limit will be breached.

Warming is occurring much faster in some cities than in their respective states, or than the United States as a whole. Check out your city’s data in the Climate Central report. Credit: Climate Central, CC BY 4.0

Warming trends in the United States are most pronounced in the Southwest, where cities have warmed an average of 1.9°C (3.5°F) since 1970. And in some cases, cities are warming much faster than whole states. Three of the five cities that have warmed the fastest since 1970 are in the Southwest: Reno, Nev., with an increase of 4.4°C (7.9°F), Las Vegas, with an increase of 3.3°C (6.0°F), and El Paso, Texas, with an increase of 3.3°C (5.9°F). 

 
Related

•  Read the Climate Central Report: Fastest-Warming U.S. States and Cities
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The effects are evident at the national, state, and local levels. Temperatures have warmed in 240 of the 242 cities analyzed by Climate Central. Harrisonburg, VA and Monterey, CA were the only two cities analyzed that have not warmed since 1970.

The report highlights some good Earth Day news, however, and points out that solar and wind power generation is at an all-time high in the United States, accounting for 19% of the electricity generated in the country in 2025 despite those industries facing recent headwinds from the federal administration. 

“Every fraction of a degree [of warming] that we prevent does matter, for our health, for our communities, and for the world that we’re passing on to the next generations,” Winkley said. 

—Grace van Deelen (@gvd.bsky.social), Staff Writer

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Lakes are often described as "hotspots" in the global carbon cycle, yet quantifying their "breath"—the exchange of carbon dioxide (CO2) between water and the atmosphere—has long been notoriously difficult due to extreme variability across time and space and a shortage of long-term, high-resolution observational data. As a result, they have remained as a missing piece in regional carbon accounting.

Mud-rich coastlines could face a greater tsunami risk, at least that may have been the case for the 2011 Tōhoku-oki tsunami that killed more than 19,000 people and led to the Fukushima Daiichi nuclear disaster. According to a new study published in the Journal of the Geological Society, mud may have made the catastrophic ocean waves more destructive than they might otherwise have been.

Geoengineering could protect the Amazon rainforest from climate change, new research shows. Stratospheric aerosol injection (SAI) aims to artificially cool Earth by increasing the reflection of incoming solar radiation, thereby offsetting warming caused by anthropogenic greenhouse gases. SAI is designed to mimic explosive volcanic eruptions by injecting aerosols into the stratosphere.

Planting more trees will decelerate climate change only if those trees are placed in optimal locations—primarily the tropics and subtropics—suggests new research published in Communications Earth and Environment. However, planting trees in locations like Alaska, Siberia, and large parts of the United States could actually lead to warming, said lead author and doctoral student at ETH Zurich Nora Fahrenbach.

Much of the current thinking in nature-based solutions, Fahrenbach said, is based on the idea that “more is better.”

As in, “we’ll plant a trillion trees, or we’ll plant more than a trillion trees, and we are going to get more cooling, right?” Fahrenbach said. “That’s something we show is just not the case.”

Fahrenbach researches reforestation potentials, or global maps that identify areas where trees could be planted to mitigate climate change. In this work, she and her colleagues compared three prominent reforestation potentials to determine the effect of tree placement on local and global temperatures.

One scenario involved reforesting about 926 million hectares focused mostly on the tropics and resulted in about 0.25°C of cooling by 2100. Another called for reforesting 894 million hectares, including large areas in northern temperate and polar latitudes, and resulted in 0.13°C of cooling by 2100.

The third scenario involved planting forests strategically over only 440 million hectares of mostly tropical and subtropical land (less than half of the area covered in the other scenarios) but also resulted in 0.13°C of cooling. Geography, the findings suggest, may matter more than quantity when it comes to the cooling benefits of reforestation efforts.

Let’s Get (Biogeo)physical

The researchers modeled all three scenarios using the same parameters: Trees were planted from 2015 to 2070 and then remained steady in their population until 2100.

Planting trees in one area doesn’t just change the local temperature but has effects across the world.

All three models identified reforestation opportunities in regions such as the eastern United States, Amazonia, the Congo rainforest, and eastern China, as well as regions for which reforestation would not be as impactful, such as polar regions in the Northern Hemisphere. The researchers also found significant temperature changes across the Atlantic and Indian oceans as a result of atmospheric changes induced by reforestation, demonstrating an interconnected reality: Planting trees in one area doesn’t just change the local temperature but has effects across the world.

These local and nonlocal effects can be explained by a combination of biogeochemical and biogeophysical effects.

A biogeochemical effect relates to the movement of chemicals or chemical elements, such as trees absorbing carbon from the atmosphere.

A biogeophysical effect relates to the physical results of changing the land’s surface: Placing a tree in a snowy region, for instance, decreases the land’s albedo, meaning it causes the land surface to become darker and absorb more light, leading to more local heat. This rise in surface temperature also raises air temperature, creating cascading effects on wind patterns and oceanic currents.

Considering both processes together is essential for understanding whether a net cooling or net heating effect exists, but most policies focus only on biogeochemical effects, seeing trees solely for their ability to absorb carbon from the atmosphere, Fahrenbach said. They include prominent international policies such as the Paris Agreement and the United Nations’ Framework for REDD+.

“Really, we would also need to consider the biogeophysical effects,” Fahrenbach said. “That’s harder to do, right, considering those nonlocal effects, because just imagine, some country is going to plant a lot of trees, and that’s going to lead to warming somewhere else.”

A Call to Policymakers

Emilio Vilanova, a forest ecologist at the climate action nonprofit Verra, wrote by email, “The most important message for me is that this study emphasizes something that is often not well addressed in reforestation projects: Reforestation is not just about planting trees—it’s about designing where new forests go to maximize benefits and avoid unintended consequences.”

“Reforestation is a helpful tool, not a stand-alone solution to climate change.”

Vilanova also said the study puts the potential for reforestation efforts to address climate change in perspective. “Even very large reforestation efforts would only reduce global temperatures by about 0.13–0.25°C by the end of the century,” he said. “While meaningful, this finding also reinforces that reforestation is a helpful tool, not a stand-alone solution to climate change.”

Though the limited potential for change is sobering, the authors and Vilanova pointed out that this change does matter and that it matters how we think of our approach. They advocate for policies that adopt reforestation strategies based on location and that acknowledge both the local and nonlocal effects of reforestation.

“We really need to make sure that where we plant first, it has benefits locally, it has benefits globally,” Fahrenbach said.

—Andrew Meissen (@AndrewMeissen), Science Writer

22 April 2026: This article was updated to correct Nora Fahrenbach’s position at ETH Zurich.

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Citation: Meissen, A. (2026), Location, location, location: The “where” of reforestation may matter more than the extent, Eos, 107, https://doi.org/10.1029/2026EO260125. Published on 22 April 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’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

The evolution of rivers that split into multiple channels is a scientific challenge in terms of modeling and prediction. On the other hand, these rivers are widespread and play a key role for ecosystems’ life, groundwater recharge, and therefore, water security. They are also extremely sensitive to hydroclimatic changes, leading to shifts in precipitation, erosion and sediment transport.

Zhao et al. [2026] investigate the drivers of river evolution for 97 multithread river reaches worldwide, spanning diverse climates and morphologies. The study reveals the key role of intermittency for river evolution. In particular, higher flow intermittency could lead to more even flow partitioning among threads, therefore impacting hydrology and ecosystems. With flow variability increasing after climate change, rivers are likely to increase their thread count, thus impacting livelihoods and ecosystems.

Two example multithread reaches shown in Landsat images from (b) the Irtysh River (wandering) and (c) the Yukon River (braided). Credit: Zhao et al. [2026], Figure 1(b,c)

Citation: Zhao, F., Ganti, V., Chadwick, A., Greenberg, E., McLeod, J., Liu, Y., et al. (2026). Global hydroclimatic controls on multithread River dynamics. AGU Advances, 7, e2025AV002166. https://doi.org/10.1029/2025AV002166

—Alberto Montanari, Editor-in-Chief, AGU Advances

Text © 2026. The authors. CC BY-NC-ND 3.0
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New climate stripes for cities and countries all over the world have been launched to mark Earth Day (April 22). The updated graphics, which now include an additional stripe to represent temperatures from 2025, show the rapid impact that global warming is having on individual nations and regions.

SummaryDistributed Acoustic Sensing (DAS) captures seismic wavefields through precise measurement of phase changes in back-scattered laser pulse signals in an optical fiber that reflect distributed strains or strain rates over continuous fiber segments. The limitation of the DAS wavefield measurement for near surface imaging remains unclear and is worthy of verification with conventional dense nodal arrays. This study compares co-located DAS and dense nodal array recordings in near-surface active surveys conducted in Shenzhen, China. Our field experiment reveals the spatially fixed, step-like distortions of coherent signals in DAS wavefield recordings. These artifacts are attributed to the gauge-length spatial average acting upon fiber segments with heterogeneous sensitivity, which can arise from variations in backscatter intensity and cable coupling conditions. These distortions cause partial deviations between waveforms of DAS and co-located seismometer from their theoretical relationship. A statistical comparison of phase differences between DAS and seismometer waveforms across all nodal points reveals a normal distribution, indicating the prevalence of such distortions in DAS recordings. Moreover, the distortion becomes more severe as frequency increases, resulting in overly dispersed phase difference distributions between DAS and seismometers. This leads to discrepancies in the dispersion curves extracted from them at high frequencies, as dispersion extraction depends on the relative energy peaks contributed by the dominant channels. This study demonstrates that within the frequency range not severely affected by distortion, DAS can effectively extract comparable dispersion curves and velocity structure profiles in place of the nodal array for near-surface imaging applications, as validated through full-profile comparisons. But the DAS wavefield distortions limit advanced applications of the complete wavefield for better subsurface characterization, and imply that DAS data simulation and instrument response analysis should consider channel ensembles.

Soil biologist Eric Slessarev has some advice for conservationists, landscapers, and farmers with fallow fields: Go touch deep-rooted grass. Or better yet, go plant some. Slessarev, an assistant professor of ecology and evolutionary biology in Yale's Faculty of Arts and Sciences, is the first author of a new study in Earth's Future showing that deep-rooted grasses store significantly more carbon in their root biomass than shallow-rooted crops—without harming the existing organic material already in the ground.