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Some species of fig trees store calcium carbonate in their trunks—essentially turning themselves (partially) into stone, new research has found. The team of Kenyan, U.S., Austrian, and Swiss scientists found that the trees could draw carbon dioxide (CO2) from the atmosphere and store it as calcium carbonate 'rocks' in the surrounding soil.

Author(s): Koji Kikuchi and Hiroshi Akatsuka

Nonequilibrium plasma has attracted significant attention owing to its excellent physical properties, which are highly valued by the industrial community. However, determining the electron temperature in nonequilibrium plasmas proves challenging unless the energy distribution function is approximate…

[Phys. Rev. E 112, 015201] Published Mon Jul 07, 2025

Author(s): B. Disson, N. Bonifaci, O. Lesaint, C. Poulain, R. Dussart, and S. Iseni

Breakdown in Argon at nanoscale interelectrode gaps is studied to highlight the deviation from Paschen's law prediction. The discharge occurs between gold-plated electrodes in a setup similar to a planar configuration. A fast cutoff system allows the measurement of up to one hundred breakdowns for e…

[Phys. Rev. E 112, 015202] Published Mon Jul 07, 2025

SummarySeasonal variations in Nepalese seismicity have been reported with varying degrees of confidence. We re-investigate these claims by analysing 20 years of Nepalese seismicity before the 2015 Gorkha earthquake, as detected by the Nepalese national network, and focusing on earthquakes located along the eastern and central sections of the Nepalese Main Himalayan Thrust. Using several declustering techniques, we find no statistically robust evidence of seasonal seismicity in the studied record, regardless of magnitude threshold above completeness. This suggests that previously reported seasonality may be restricted to the western section of the Nepalese orogeny, may be an artefact, or may indicate that nucleation times of earthquakes are longer than the year. We also investigate potential annual variations in the Gutenberg-Richter b-value, given its recent observed modulation by transient stressing. Additionally, we use large-scale mass redistribution estimated from the monthly gravity field retrieved from the Gravity Recovery And Climate Experiment and Follow-On (GRACE/-FO) missions, to resolve stress variations at depth induced by transient surface loads. We find that the mean annual b-value peaks when seasonal Coulomb stress rates reach their minimum value at the height of the summer rainy season. When considering the combined effect of tectonic and seasonal loading, this corresponds to a recurring period of stress reversal, when Coulomb stress momentarily decreases. This suggests that periodic clamping of the Main Himalayan Thrust reduces the likelihood of earthquakes growing to larger magnitudes in accordance with hierarchical rupture models. The susceptibility of b-value to stress variations of roughly 0.1 points.kPa−1 is consistent with recent estimates of b-value sensitivity to transient loading, although it remains high when compared to the stress-dependency associated with both static differential stress, and with long-term evolution during the seismic cycle. This discrepancy points to the large impact of stress transients on the dynamics of seismic rupture.

SummaryThe goal of this paper is to present considerations, steps and tools to perform statistical analysis of InSAR time series by relying on multichannel singular spectrum analysis (M-SSA). We apply these tools to Sentinel-1 InSAR time series processed for Pacaya Volcano in Guatemala in two steps. First, we produce, in a data-adaptive way, estimates of data points to obtain evenly sampled time series. The resulting time series are then decomposed using M-SSA into long-periodic nonlinear trends and oscillatory modes providing a sparse representation of the signals present in the data. Combining M-SSA that includes varimax rotation with power spectrum analysis augments the physical interpretability of the InSAR dataset presented herein. Monte Carlo SSA hypothesis testing further helps estimate the statistical significance of the M-SSA modes with respect to a red-noise null hypothesis. The dominant frequencies of the main oscillatory modes retained correlate with frequency peaks of the seasonal variability of the regional hydrological system, as determined from correlograms of rainfall time series. The spatial patterns of the significant modes correlate with three types of geological structures present at Pacaya volcano: the volcanic edifice, the 2010 and 2014 lava flows, and a collapse scarp dividing the volcanic edifice into an eastern and western part. These findings suggest that, when including the complementary tools presented herein, M-SSA is able to provide a reliable statistical picture of InSAR datasets and that the main M-SSA modes are geophysically meaningful.

SummaryMachine-learning-based phase pickers have been successfully leveraged to build high-resolution earthquake catalogs using seismic data on land. However, their performance when applied to ocean bottom seismic (OBS) data remains to be evaluated. In this study, we first adopt three machine-learning-based phase pickers—EQTransformer, Pickblue, and OBSTansformer—to build three earthquake catalogs for the 350-km-long Blanco oceanic transform fault (BTF) based on a year-long OBS deployment. We then systematically compare these catalogs with an existing catalog which utilized a traditional workflow. Results indicate that the Pickblue-based catalog documents more events and/or provides better-constrained locations than the other catalogs. The different performances of the three phase pickers suggest that detailed assessment of catalogs built using automatic workflows is necessary to prevent misinterpretations, especially when applied to regions without training samples. The Pickblue-based catalog reveals seismicity gaps in three extensional segments of BTF, which likely represent aseismic slip zones affected by seawater infiltration. Furthermore, most earthquakes are shallower than the 600 °C isotherm predicted by a half-space conductive cooling model, except for the Blanco Ridge segment which has hosted 80 per cent of the Mw > 6.0 earthquakes along BTF since 1976. These Blanco Ridge deep earthquake clusters can be explained by hydrothermal cooling or the serpentinization of mantle peridotite due to seawater infiltration along conduits created by the deeper ruptures of large earthquakes. Our analyses also demonstrate the importance of careful examination of automatically produced earthquake catalogs since mislocated events can lead to very different interpretations of fault slip modes from seismicity distribution.

SummarySeismic wave multiples have historically been treated as noise when performing velocity model building or imaging and have, therefore, typically been attempted removed from the data during preprocessing. Recently, there has been interest in developing methods to utilise their information to better illuminate areas poorly covered by primary seismic wave energy. These often either predict and iteratively apply information from reflected wave multiples or incorporate multiple information by retaining surface reflected waves in a full/reflection waveform inversion framework. Such approaches have provided insight into the behaviour of reflected wave multiples, both alone and when mixed with multiples of other wave types. Much less is known about the behaviour of diving wave multiples alone. In velocity model building using full waveform inversion, diving waves are a significant source of the low-frequency information needed to update low wavenumbers. Here, we derive equations for the ray paths, traveltime, relative geometric spreading, and acoustic reflection coefficient of diving wave multiples when the vertical velocity increases linearly with depth in both an acoustic isotropic model and an acoustic factorized vertical transverse isotropic anisotropic model with constant anisotropy. These are used to investigate the effect of increasing the number of surface reflections. We also study their interference by deriving equations for the amplitude spectrum and traveltime of a wavetrain consisting of a sum of diving wave multiples, where the number of surface reflections increases linearly. Our results show that the properties of the diving wave multiples converge to those of the direct wave as the number of surface reflections approaches infinity. For the relative geometrical spreading in the acoustic factorized vertical transverse isotropic anisotropic model, this leads to a new equation describing the direct wave when the vertical velocity increases linearly with depth. This equation has an anisotropic dependence solely on the η parameter, indicating that η has the largest anisotropic influence on the relative geometrical spreading of the diving wave and its multiples. Both the amplitude spectrum and traveltime of the wavetrains show signs of dispersion. The dispersion primarily arises from the traveltime differences between the diving wave and the diving wave multiple that undergoes one surface reflection. In the amplitude spectrum, this causes notches to appear at different offsets that shift downward in frequency as the offset increases. Adding diving wave multiples that undergo more reflections to the sum significantly changes the amplitudes at short offsets. At mid to long offsets, this primarily affects the amplitude around existing minimum and maximum points, with new small local peaks and troughs additionally being induced at long offsets. The notches in the amplitude spectrum cause complex phase behaviour at different offsets, resulting in difficulties computing the traveltime beyond their appearance. Before this behaviour emerges, we observe low-frequency wavetrains to arrive earlier than those with higher frequencies. We attribute this to the lower-frequency wavetrains sampling the higher seismic velocities deeper in the subsurface. Overall, our results show a significant difference between properties in the acoustic isotropic model and the acoustic factorized vertical transverse isotropic anisotropic model.

For years, scientists have debated whether a giant thick ice shelf once covered the entire Arctic Ocean during the coldest ice ages. Now, a new study published in Science Advances challenges this idea as the research team found no evidence for the presence of a massive ~1km ice shelf. Instead, the Arctic Ocean appears to have been covered by seasonal sea ice—leaving open water and life-sustaining conditions even during the harshest periods of cold periods during the last 750,000 years.

Rising rural populations, drought and climate change are making water scarcity a problem in country townships—with more efficient handling of sewage system wastewater part of the solution.

The peer-reviewed study, "The Earth4All scenarios: Human well-being on a finite planet towards 2100," uses a system dynamics-based modeling approach to explore two future scenarios: Too Little Too Late, and the Giant Leap. The model presented in the paper provides the scientific basis for the analysis and policy recommendations of Earth for All: A Survival Guide for Humanity, published in 2022.

SummaryEfficient simulation of controlled-source electromagnetic (CSEM) methods in complex geological settings is critical for accurate subsurface imaging and resource evaluation. This study presents an advanced adaptive finite element algorithm leveraging non-conforming arbitrary hexahedral meshes and combining the flexibility of adaptive refinement with the accuracy of high-order basis functions to solve challenges in electromagnetic field modelling. We present a high-order finite element algorithm for electromagnetic geophysics that supports adaptive refinement on arbitrary hexahedral meshes, a capability not commonly available in existing implementations. The proposed algorithm resolves sign conflict issues inherent in non-conforming meshes by employing global vertex indices and adjusting constraint matrices, ensuring the tangential continuity of the electromagnetic field across the computational domain. Adaptive refinement is guided by goal-oriented error estimation, enabling precise solving for the electromagnetic response while maintaining computational efficiency. Numerical examples validate the algorithm’s accuracy and performance. In a steel-cased well model, the computational accuracy of our algorithm is verified by comparison with the 3-D cylindrically symmetric algorithm of the open-source software SimPEG. Furthermore, it is demonstrated that arbitrary hexahedral meshes can achieve accurate modelling of the steel casing with a reduced mesh count. The application to the Vallès Basin model demonstrates substantial computational savings using arbitrary hexahedral meshes compared to tetrahedral meshes. Finally, the algorithm successfully models a large-scale oil-gas reservoir, illustrating its robustness in addressing complex geological scenarios and its potential for monitoring dynamic processes such as water intrusion during resource extraction. These results establish the proposed method as a reliable and efficient forward modelling tool for controlled-source electromagnetic applications, providing significant improvement in flexibility, accuracy, and computational efficiency.

SummaryThe base of the Earth's lower mantle is characterized by large seismic velocity anomalies, known as large low-velocity provinces (LLVPs) (Garnero et al., 2016). There are several hypotheses related to the origin of LLVPs, such as remnants of Earth's early differentiation (Labrosse et al., 2007; Lee et al., 2010) and buried relics of proto-Earth's mantle after the Moon-forming giant impact (Yuan et al., 2023). However, the geodynamical implications, such as the role of LLVPs as driving mechanisms of plumes or subducted slabs, are not well resolved because some observations of the polarization of seismic velocity at LLVPs use the azimuthal anisotropy of shear wave splitting. Here, we combine new observations of antipodal PKPab seismic waves with the adjoint method to perform an inversion of the radially anisotropic Vp structure at the base of the lower mantle. We have carefully examined antipodal stations with sufficient signal to noise ratios for both the vertical and horizontal components over the past 30 years and selected 23 source‒receiver pairs with epicentral distances greater than 178.0 degrees and Mw values less than 7.0. We calculate synthetic seismograms with an accuracy of 6.9 s and perform an inversion of the radially anisotropic Vp structure at the base of the lower mantle by the adjoint method. The results of our inversion show that vertically polarized Vp is dominant within the LLVPs of the Pacific and African regions. These features are characterized by relatively small spots of high vertically polarized Vp anomalies, which may be interpreted as the locations of ascending mantle plumes inside LLVPs in the Pacific region.

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.

On 3 June, the U.S. House of Representatives passed a 940-page spending bill containing President Donald Trump’s domestic policy agenda. After the Senate passed the bill 2 days ago, it cleared the House by a four-vote margin and it will now head to Trump’s desk to be signed into law.

The bill provides trillions of dollars in tax cuts, boosts the fossil fuel industry, and dismantles incentives for clean energy, fulfilling Trump’s campaign promise to remake the U.S. energy economy in favor of oil and gas. 

“Congress has betrayed the working people of this country. This budget bill is the largest-ever transfer of wealth from working families to the ultra-rich and one of the most environmentally destructive pieces of legislation in U.S. history,” said Collin Rees, U.S. campaigns manager at Oil Change International, a clean energy advocacy group, in a statement. 

 
Related

•  How the G.O.P. Bill Will Reshape America’s Energy Landscape
•  A List of Nearly Everything in the G.O.P. Bill, and How Much It Would Cost or Save
•  Chart: ​‘Big, Beautiful Bill’ would cause energy bills to go up in every state
• The Most Perverse Part of the ‘Big, Beautiful Bill’
•  Get Involved: AGU Science Policy Action Center
 

Some of the provisions that most concerned renewable energy and environmental advocates ultimately did not make it into the bill. A tax on future wind and solar projects was removed; the bill no longer mandates the scale of public land sales; and tax credits for companies building nuclear, hydroelectric, and geothermal power plants were not targeted by the bill, according to the New York Times. 

“America, get ready for a safer, stronger, more affordable, and Energy Dominant future,” Doug Burgum, secretary of the U.S. Department of the Interior, wrote on X. According to a 25 February report from the Clean Energy Buyers Association, repealing clean energy tax credits, which the bill calls for, would raise electricity prices for U.S. residents by nearly 7% on average by 2026.

Contained within the bill are provisions related to climate, energy, and Earth science that would: 

• Phase out tax credits that have been in place for decades incentivizing wind and solar power projects. “We’ll continue to build out renewables, but we’ll build out a lot slower,” David Carrol, chief renewables officer for ENGIE North America, a major power plant developer, told the New York Times. 
• Repeal tax credits for consumers who buy new or used electric cars, as well as incentives for businesses to buy electric trucks.
• Postpone fees on methane leaks from oil and gas operations.
• End tax credits for homeowners to upgrade energy efficiency in their homes. In 2023, 3.4 million Americans took advantage of these incentives, according to Rewiring America, an electrification advocacy nonprofit.
• Provide tax breaks for oil and gas producers.
• Rescind unspent funding from President Joe Biden’s Inflation Reduction Act. 
• Mandate that millions of additional acres of federal land be made available for mining. 
• Provide tax breaks for U.S. producers of metallurgical coal (a form of coal used to make steel) and lower royalty rates for coal companies that mine on federal lands.
• Mandate oil and gas lease sales in the Gulf of Mexico, the American West, and Alaska’s Arctic National Wildlife Reserve.

“This bill will be the most transformational legislation that we’ve seen in decades in terms of access to both federal lands and federal waters,” Mike Sommers, chief executive of the American Petroleum Institute, told CNBC. “It includes almost all of our priorities.”

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 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.

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.

A group of EPA scientists who signed an open letter voicing their dissent from Trump administration policies have been placed on administrative leave.

The letter, addressed to EPA administrator Lee Zeldin, was published 30 June.

As of Thursday afternoon, all 620 signatories are listed as anonymous. However, initially, more than 300 were identified as EPA staffers, and 170 of those staffers chose to be named, according to the Washington Post. Now, about 140 of them have been placed on administrative leave, according to The Hill, E&E News, The New York Times, and other outlets.

“The Environmental Protection Agency has a zero-tolerance policy for career bureaucrats unlawfully undermining, sabotaging and undercutting the administration’s agenda as voted for by the great people of this country last November,” wrote EPA press secretary, Brigit Hirsch, in a statement.

 
Related

•  Declaration of Dissent
•  EPA places staffers who signed ‘dissent’ letter on leave
•  EPA puts 139 employees on leave who criticized administration
• E.P.A. Suspends 144 Employees After They Signed a Letter Criticizing Trump
• Roughly 140 EPA staffers who signed ‘dissent’ letter are put on leave
•  Get Involved: AGU Science Policy Action Center
 

Marie Owens Powell, president of American Federation of Government Employees Council 238, EPA’s largest union, told E&E News that EPA’s actions were “disgraceful” and an “obvious retaliation for individuals expressing their beliefs. She added that the union is investigating its options for legal recourse.

As of Thursday afternoon, the letter also has 4,597 “supporters and endorsers” who had added their name to a running list. The letter outlines five primary concerns:

• That the EPA is undermining public trust by “promot[ing] misinformation and overtly partisan rhetoric.” The letter calls out the use of politicized terms such as “green slush funds” and “clean coal” in EPA messaging.
• That the EPA is ignoring scientific consensus to benefit polluters. The letter states that the “administration’s actions directly contradict EPA’s own scientific assessments on human health risks” related to mercury, asbestos, greenhouse gases, and PFAS.
• That the EPA is reversing previous progress made to protect vulnerable communities. The letter references environmental justice staffers being placed on leave earlier this year and billions of dollars of cancelled grants.
• That the EPA has dismantled the Office of Research and Development (ORD). The letter suggests that placing ORD scientists in regulatory program offices “will make EPA science more vulnerable to political interference” and that budget cuts will leave the office “unable to meet the science needs of the EPA and its partners and will threaten the health of all Americans.”
• That the EPA has promoted a culture of fear. The letter cites comments from private speeches, reported by ProPublica, in which Office of Management and Budget director Russell Vought stated, “We want their funding to be shut down so that the EPA can’t do all of the rules against our energy industry because they have no bandwidth financially to do so.” And, “We want to put them in trauma.”

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

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.

Understanding where and in what quantities essential elements for life have existed on Earth's surface helps explain the origin and evolution of life. Phosphorus is one such element, forming the backbone of DNA, RNA, and cellular membranes.

On March 28, 2025, a major earthquake with a moment magnitude (Mw) of 7.7 struck Mandalay, central Myanmar (referred to as the 2025 Myanmar earthquake). This event caused severe shaking and substantial damage in Myanmar and neighboring countries. Aftershock distribution extended southward from the epicenter, indicating predominant southward rupture propagation.

Tsunami earthquakes are characterized by the generation of disproportionately large tsunamis relative to the observed ground shaking, complicating timely evacuation efforts. Understanding their generation mechanisms and associated risks is therefore critical.

Scientists have found evidence that the Asian continent was free of permafrost all the way to its northerly coast with the Arctic Ocean when Earth's average temperature was 4.5˚C warmer than today, suggesting that the whole Northern Hemisphere would have also been free of permafrost at the time.

University of Leicester-led research has revealed the start of industrial deforestation of the Malaysian rainforest and its long-lasting impact on coastal ecosystems in the skeletons of corals.

Ship traffic in shallow areas, such as ports, can trigger large methane emissions by just moving through the water. Researchers in a study, led by Chalmers University of Technology in Sweden, observed 20 times higher methane emissions in the shipping lane compared to nearby undisturbed areas.