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Shoppers may use a plastic bag for only a few minutes before tossing it in the trash. Inefficient waste disposal, however, may allow that bag to find its way into streams and, ultimately, coastal ecosystems. There, plastic pollution can imperil marine plants and animals as well as the economic value of beachfront businesses.

“Plastic bags are designed to be single use. They’re designed to be lightweight. Even if we’re trying to properly manage them, they just get into the environment more easily than other plastics,” said Erin Murphy, ocean plastics science and research manager at the Ocean Conservancy.

“These [plastic bag bans] are effective policies, regardless of the scale of governance in which you implement them.”

While many states and municipalities have plastic bag bans or require fees for customers who want a bag, there is no national policy that aims to reduce the number of plastic bags used in the United States.

But a study published last month in Science shows some promising results: In places with bag bans and fees, the number of plastic bags found on local beaches and shorelines has dropped significantly.

“A lot of the time, communities don’t feel like they can implement policy that will directly impact their communities and directly benefit their communities. This study showed that whether it’s a town or state, these [plastic bag bans] are effective policies, regardless of the scale of governance in which you implement them,” said Murphy, who was not involved in the research.

Analyzing the Trash

Study authors Anna Papp and Kimberly Oremus examined data collected from 45,067 shoreline cleanup events between 2016 and 2023. During these events, organized by the Ocean Conservancy, participants collected trash along a beach and logged their findings into the Trash Information and Data for Education and Solutions (TIDES) database.

Plastic bags are the fifth most common item found during these shoreline cleanups, making up 4.5% of all cataloged trash. (Some of the more unusual items logged include golf balls, Mardi Gras beads, and fake nails.)

Papp and Oremus cross-checked the cleanup data with 182 plastic bag policies around the United States that were enacted between 2017 and 2023. The discrepancy between the dates of the cleanup data (starting in 2016) and the policy data (starting a year later) allowed the researchers to use the 2016 data as a control to evaluate how trends in plastic bag litter may have changed in response to local or state-level regulation.

“Comprehensive data on plastics in the environment can be challenging to find, so the cleanup data offered a new way of measuring plastic bag litter in the environment. This, combined with the wide reach of bag policies in the U.S. in recent years, made our study possible,” said Papp, an environmental economist at the Massachusetts Institute of Technology.

A Broad Spectrum of Bans

Across the country, a hodgepodge of legislation exists to manage plastic bag waste, from strict bans (like the ones implemented in New Jersey, where single-use paper bags are also limited), to partial bans (like the ones in California, targeted at large retailers), to required fees (as in Oregon, where retailers must charge at least 5 cents for a thick, presumably reusable plastic bag). In addition to statewide legislation, hundreds of municipalities have their own plastic bag policies.

“During our data collection phase, I was initially surprised by the reach of plastic bag policies. We estimate that now one in every three Americans lives in an area with some bag policy,” said Papp.

Papp and Oremus were able to document the effectiveness of such policies, regardless of their reach. In places where some form of plastic bag legislation exists, data showed a 25%–47% decrease in the proportion of plastic bags recovered in coastline cleanups. Although all policies aimed at reducing plastic bag litter were effective, researchers found that those implemented at the state level correlated most strongly to reducing the amount of plastic bag waste found during beach cleanups.

“In some ways it’s like, well, of course, if you use fewer plastic bags, you’re going to find fewer plastic bags on the beach, but it’s good that [researchers] documented that in a quantitative way,” said Susanne Brander, an ecotoxicologist at Oregon State University who was not involved in the study. “We need those data in order to convince additional lawmakers and agencies to take this seriously and to think not just about plastic bags, but about other single-use items as well.”

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Policy success: Fees and bans on plastic bags reduce beach trash, Eos, 106, https://doi.org/10.1029/2025EO250247. Published on 14 July 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.

Tropical cyclones hundreds of kilometers away from the Philippines are often more responsible for heavy rainfall than those that hit the country directly during the annual "Habagat" or southwest monsoon season from July to September, according to new research published in Atmospheric Research.

The cleanup of air pollution in East Asia has accelerated global warming, a new study published today (Monday, 14 July) in the journal Communications Earth and Environment has found.

A new paper (Dalal et al. 2025) in the journal Engineering Geology examines movement of a major landslide complex in India. It shows that the slope reactivated in 2018, probably as a result of the loss of vegetation and poor management of water.

Loyal readers will remember a series of posts that I made back in early 2023 regarding accelerated movement of the complex landslide system located beneath the town of Joshimath located in the Himalaya in Uttarakhand, India. At this time, there was a significant increase in the movement rate of the landslide, causing substantial damage to structures within the town.

Joshimath is located at [30.5526, 79.5628]. This is a Google Earth image of the town in 2022. The complex landslides in the area are quite easy to see:-

Google Earth image of the town of Joshimath in northern India.

A very nice paper (Dalal et al. 2025) has been published in the journal Engineering Geology. The authors have used InSAR to examine the long term movement pattern of the landslides – the InSAR data extends back to 2017. In it, they demonstrate that the slope did indeed undergo a phase of rapid movement in early 2023, and they link this to heavy rainfall that occurred in October 2022, which increased the pore water pressure in the slope.

But there are some interesting details in this piece of work. First, the slope actually started to move in 2018, and showed a seasonal pattern of deformation until the rapid movement even in 2023. The authors link this reactivation of the landslide at Joshimath to progressive urbanisation and removal of the vegetation canopy – modelling indicates that the factor of safety of the slope has been notably reduced by this effect. This is quite surprising as the failure at Joshimath is deep-seated, where vegetation does not normall play a major role.

Second, the analysis also highlights that “mismanaged groundwater seepage and blocked drainage paths further exacerbated slope weakening.” This is a common problem in rapidly developing Himalayan communities.

Finally, and most worryingly, Dalal et al. (2025) indicate that the slope could be undergoing progressive failure towards a catastrophic collapse. They have modelled runout scenarios for the slope, which indicate that such an event would threaten the Tapovan Vishnugad hydropower project downstream.

All of this indicates that action is needed at Joshimath. If a large-scale mitigation project is not possible (and I recognise that this would be extremely expensive and very challenging), efforts should be made to manage water (and drainage) across the whole area, and the slope should be monitored in real time.

Reference

Dala, P. et al. 2025. Deformation dynamics and hazard of slow-moving landslides: The 2023 Joshimath event, Uttarakhand Himalaya. Engineering Geology, 354, 108201. Doi: https://doi.org/10.1016/j.enggeo.2025.108201

Return to The Landslide Blog homepage Text © 2023. 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.

SummaryThis paper investigates the seismic activity and velocity structure in the Three Gorges Reservoir (TGR) region using high-quality travel time data from an extensive seismic observation network. The primary goal is to understand the relationship between the three-dimensional velocity structure and seismicity within the reservoir area. We employed advanced inversion techniques to develop detailed 3-D models of the P- and S-wave velocities and analyzed the focal mechanisms of significant seismic events. Our results reveal that there are substantial lateral variations in the upper crustal velocity structure, with high-velocity zones in the northeastern region of Badong and lower velocities in the Zigui Basin (ZGB). The sedimentary layers in the ZGB are 6–8 km thick, and low S-wave velocity anomalies extend from this depth and are correlated with the Triassic formations. The seismic activity patterns show that the earthquakes in the Badong region were concentrated along three east–west trending belts within the core of an anticline. These patterns suggest that the geological structures and fluid infiltration significantly influence the seismicity. In particular, the M5.1 Badong earthquake occurred at the boundary of a high-velocity zone and was associated with a seismic belt extending from shallow to deeper depths. The results of this study highlight the complex interactions between rock heterogeneity, fault dynamics, and fluid effects, providing a comprehensive analysis of reservoir-induced seismicity. This work provides a better understanding of the physical mechanisms driving seismic activity in large reservoir systems and provides insights relevant to seismic hazard assessment and reservoir management.

SummaryCharacterizing ore deposits or mining dumps in terms of mineral content and grain size remains a challenge. Since the 1950s the Induced Polarization (IP) method has been successfully applied in ore prospecting. However, reliably interpreting field survey data requires comprehensive laboratory studies to establish a link between the IP parameters from empirical or phenomenological models and the type and quantity of ore minerals. In this study, we use numerical electrical networks to replicate the complex electrical resistivity spectra observed in experiments on sand-pyrite-water mixtures. A network consists of a 3D assembly of resistors, representing the saturated pore space, and leaky capacitors simulating the electrical behaviour of ore minerals. A sophisticated fitting procedure enables the precise determination of resistor and capacitor parameters, ultimately leading to strong agreement between measured and synthetic IP spectra. The results obtained from the 3D network align well with the classical Pelton model, which is based on a simple equivalent circuit. Our findings indicate that the network's chargeability depends on the fraction of capacitors in the system (i.e. the number of capacitors divided by the number of capacitors and resistors), and that the Pelton time constant of the measured spectra is closely related to the resistor and capacitor parameters. We argue that a 3D approach offers a more realistic framework, paving the way for future studies on the effects of ore grain size distribution, and the spatial arrangement of ore grains.

SummaryThe most widely used method to derive global geomagnetic field models for historical and longer timescales has long been regularized non-linear least squares inversion. It is based on spherical harmonics for the spatial part and cubic B-splines for the temporal dynamics. Recently, different versions of Bayesian inversion have been applied for this purpose. Early literature on the traditionally used formalism states the inverse problem in a Bayesian setting and discusses uncertainty estimation via the posterior covariance, but this view was lost in subsequent studies in the geomagnetic community. Here we aim to provide both geomagnetic field modellers and users of such models with a comparative view of the methods to enable them to better evaluate strengths and weaknesses of different models. We first describe the connection between regularized least squares and Bayesian inversion in general form in a linear, one-dimensional setting. A fully Bayesian perspective allows interpreting the regularization term as a form of prior and offers new ways of comparing models from both approaches. We then discuss the particular case of geomagnetic field modelling. We find that in comparison to Bayesian modelling approaches the prior corresponding to the widely used regularization does not imply reasonable field properties and does not lead to meaningful uncertainty estimates.

AbstractThis study presents a refined interpretation of the Jeokjung-Chogye Basin (JCB), a confirmed meteorite impact structure in South Korea, by integrating high-resolution gravity data, microtremor measurements, and borehole information. A total of 1 700 gravity stations including 1 000 newly acquired in 2023, were used alongside horizontal-to-vertical spectral ratio (HVSR) analysis and well-log constraints to characterize subsurface structures. To isolate the impact-induced deformation from overlying sedimentary effects, gravity stripping was applied to remove the signal from post-impact ejecta deposits. The residual gravity field was analysed using dip-curvature mapping and Euler deconvolution, which revealed concentric ring structures with displaced centres. These asymmetries, corroborated by 3D forward gravity modelling using IGMAS+, suggest a northeast-to-southwest impact trajectory with an oblique incidence angle of approximately 45°, contrasting with earlier estimates of ~55° from east to west. The final 3D density model achieves a strong correlation with observed anomalies (R ≈ 0.95) and successfully resolves variations in the autochthonous and basement layers.

Despite a warming climate, bone-chilling winter cold can grip parts of the U.S. In a study appearing in Science Advances, researchers found that two specific patterns in the polar vortex, a swirling mass of cold air high in the stratosphere, steer extreme cold to different regions of the country. One pattern drives Arctic air into the Northwest U.S., the other into the Central and Eastern areas.

Tungsten (W), a hard, heat-resistant, and corrosion-resistant metal, is indispensable to modern high-tech industries—from aerospace and defense to computing. While its global distribution is uneven, most tungsten deposits share defining geological traits: close ties to highly evolved, volatile-rich granites; formation from melted sedimentary rocks (anatexis) in tungsten-rich granitoids; and occurrence in back-arc or intraplate zones rather than convergent tectonic margins. These features have long supported theories of a purely crustal origin for tungsten mineralization.

Source: Global Biogeochemical Cycles

Whether from a forest on fire or gasoline powering a car, organic matter rarely combusts completely: Remnants such as char and soot can persist in the environment for decades. Over time, as physical and biological processes break down the scorched leftovers, some of the carbon they contain leaches into groundwater, lakes, and rivers, eventually making its way to the ocean.

This carbon, known as dissolved black carbon (DBC), represents the ocean’s largest identified reservoir of stable dissolved organic carbon. Yet the isotopic signature of DBC in the ocean does not match what rivers alone supply. This discrepancy suggests there are one or more unknown sources of DBC entering the ocean that are not accounted for in the global carbon budget.

To address this knowledge gap, Zhao et al. conducted six field surveys along China’s eastern coast, in the Jiulong, Changjiang (Yangtze), and Pearl River estuaries. By gathering samples during all four seasons, the researchers aimed to quantify changes in DBC and shed light on how it moves through coastal ecosystems toward the sea. Prior research focused only on individual estuaries and didn’t always account for how processes may vary across seasons and tide cycles.

The findings from the new study reveal submarine groundwater discharge (SGD) as a likely missing source of DBC. The scientists observed that as seawater pushed into estuaries during flood tides, DBC levels rose. Conversely, when water flowed out of the estuaries during ebb tides, DBC concentrations fell. They suggest that this pattern occurs because the salty ocean water that mixes into the estuaries during flood tides promotes the release of DBC from groundwater into the water column.

The researchers estimate that globally, SGD contributes approximately 20% of the riverine discharge of DBC that enters the ocean each year. Given the role that DBC plays in carbon sequestration and biogeochemical cycling in the ocean, the findings underscore the importance of including estuarine processes in global carbon models. (Global Biogeochemical Cycles, https://doi.org/10.1029/2025GB008532, 2025)

—Aaron Sidder, Science Writer

Citation: Sidder, A. (2025), Tracing black carbon’s journey to the ocean, Eos, 106, https://doi.org/10.1029/2025EO250248. Published on 11 July 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.

Marine scientist Matthew Mulrennan was piggybacking on a tourist vessel around the Antarctic Peninsula’s coasts, surveying a seabed teeming with life, when his underwater cameras came across a gray seafloor scarred with ridges.

Anchoring had churned up the sediment, leaving lifeless patches strewn with crushed sponges. The damage had narrowly missed three giant volcano sponges, which can live for up to 15,000 years and grow larger than the divers who study them.

“We saw a lot of life on the seafloor and not a lot of regulation around its protection,” said Mulrennan, founder of KOLOSSAL, an ocean exploration and conservation nonprofit in California.

Anchoring churns up the seabed, destroying life and leaving regular furrows, akin to plow marks. Credit: Matt Mulrennan/KOLOSSAL

Mulrennan’s footage, which was released alongside a recent study in Frontiers in Conservation Science, provides evidence that the seafloor impacts of anchoring now extend to remote polar waters.

A Vulnerable Ecosystem

Retreating sea ice is opening Antarctica’s coast to increasing amounts of ship traffic, including tourist cruises. “Most visitors want to see the penguins, seals, and whales,” Mulrennan said, but the seafloor, which is home to 95% of the continent’s biodiversity, “is where the real action is.”

With large areas of the Southern Ocean unexplored, scientists estimate that as many as 17,000 species might live on the seabed.

Colorful life lies on the Antarctic seabed, including the 50-armed death star starfish and the giant volcano sponge, the oldest animal on the planet. Credit: Matt Mulrennan/KOLOSSAL

Many Antarctic species, such as the giant volcano sponge, are uniquely adapted to extreme cold and play an important ecological role, Mulrennan said. “They filter water, sequester carbon, provide food and habitat.”

“These are probably some of the most vulnerable ecosystems to anchor in in the world.”

“These are probably some of the most vulnerable ecosystems to anchor in in the world,” Mulrennan said. Although relatively fast-growing tropical reef communities may start to recover from anchoring in roughly a decade or so, “it could take hundreds or potentially thousands of years for Antarctic ecosystems to grow in the exact same way,” he said.

Mulrennan surveyed 36 sites around the Antarctic Peninsula between 2022 and 2023, finding anchor damage only at Yankee Harbour on Greenwich Island.

He showed the footage to Sally Watson, a geophysicist at Earth Sciences New Zealand and a study coauthor, who matched the characteristically uniform, curved gouges to anchor damage observed elsewhere.

Anchors can dig through 80 centimeters of sediment, but most damage is caused by the connected chain, which sweeps sideways because of winds and currents and can excavate 50 centimeters of sediment where it lies on the seafloor. From above, the scars resemble a broomstick, explained Watson, composed of one main scour stemming from the anchor connected to a series of branching gouges dug as the chain shifts in the sediment.

“Most of the really important life is within the uppermost 10 centimeters,” Watson said. “Anchoring blasts through that.”

In 2022, Watson and her colleagues published the first estimate of anchoring’s global footprint, putting its damage on par with bottom trawling.

Anchors and Icebergs

Anchoring isn’t the only thing churning up the Antarctic seafloor. Icebergs can drift into shallow water and drag along the seabed—causing well-documented impacts around the Antarctic Peninsula’s coastline, said Lloyd Peck, a marine biologist from the British Antarctic Survey who was not involved in the study.

Diver surveys show that iceberg scouring can destroy up to 99% of life on the shallow seabed. Regularly uprooted by icebergs, shallow-living species recover relatively quickly, in around a decade.

Waters deeper than 30 meters are struck less often, Peck said, allowing complex, slow-growing organisms to establish themselves. The slow growth also means these deeper areas take longer to recover.

At Yankee Harbour, Mulrennan observed the scours in waters 70 meters in depth, so he is confident they were caused by anchoring rather than by icebergs. Peck agreed, noting the large, slow-growing volcano sponges nearby. “That suggests the iceberg scouring is going to be very rare here,” he explained.

“Activities in Antarctica are bound by strict conservation rules, yet ship anchoring goes almost completely unregulated.”

Peck said that compared to iceberg scouring, anchoring will have a minor imprint across the Antarctic Peninsula. But the location of an anchoring impact is as important as its scope, he noted. “This is about disrupting sheltered areas that icebergs can’t reach.”

Species-rich areas in deeper waters, such as Yankee Harbour, could be acting as refugia, Peck explained, reseeding surrounding areas with life after they are scoured by icebergs. To avoid wider ecosystem impacts, he said, “we should be making every effort to avoid anchoring in areas of undisturbed biodiversity.”

In addition to tourist cruises, research vessels, shipping fleets, and private yachts operate in Antarctic waters. “Activities in Antarctica are bound by strict conservation rules” for all visitors, Mulrennan said, “yet ship anchoring goes almost completely unregulated.”

Watson and Mulrennan have several suggestions to mitigate anchoring impacts, including limiting time vessels spend on anchor and the use of designated anchorages, where ecological impact can be monitored and limited.

Above all, anchoring needs wider recognition as a conservation concern, not just in Antarctica but globally, Watson said. “I think we could do better, by changing the way we anchor, the gear we use, but at least understanding that this is not a no-consequences game.”

—Erin Martin-Jones, Science Writer

Citation: Martin-Jones, E. (2025), Anchoring is damaging the fragile Antarctic seabed, Eos, 106, https://doi.org/10.1029/2025EO250246. Published on 11 July 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.

As Great Salt Lake's levels continue to sag, yet another strange phenomenon has surfaced, offering Utah scientists more opportunities to plumb the vast saline lake's secrets.

Rivers are Earth's arteries. Water, sediment and nutrients self-organize into diverse, dynamic channels as they journey from the mountains to the sea. Some rivers carve out a single pathway, while others divide into multiple interwoven threads. These channel patterns shape flood risks, erosion hazards and ecosystem services for more than three billion people who live along river corridors worldwide.

The remains of landscapes thought to have formed when ancient rivers flowed across East Antarctica have been discovered—and could help predictions of future loss from the ice sheet.

A new study conducted by geologists from the University of Florida and the University of Maryland reveals that, as land is exposed by melting glaciers, chemical reactions in the newly uncovered glacial sediments initially suppress greenhouse gas emissions.

A new study published in Nature Communications has found that 17.31% of tropical tree cover—an area spanning 395.9 million hectares (Mha)—has been consistently overlooked by global forest monitoring systems, exposing significant gaps in efforts to track deforestation and ecological degradation.

Four years ago, summer floods in Limburg—in the south of the Netherlands—drastically altered the riverbed of the Meuse, making accurate high-water forecasts even more difficult than usual. "This shows just how vulnerable and unpredictable the Meuse really is," says researcher Hermjan Barneveld.

A new real-time monitoring system captures minute-by-minute changes in toxic metals resulting from traffic pollution. Research indicates that non-exhaust sources, including brake wear, significantly contribute to urban health risks.

A total collapse of the roughly 80-mile-wide Thwaites Glacier, the widest in the world, would trigger changes that could lead to 11 feet of sea-level rise, according to scientists who study Antarctica. To better predict fractures that could lead to such a collapse—and to better understand the processes driving changes in Antarctic ice shelves—a team led by researchers at Penn State developed a new method to evaluate cracks that destabilize ice shelves and accelerate those losses.