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Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Water Resources Research

Using a combination of innovative approaches including observations and models, Platt and Dugan [2025] demonstrate how post-winter storm pulses of road salt lead to high concentrations of toxic substances in runoff water.

Surprisingly, the authors find that dilution is not an effective solution in this case, as discharge and snowfall magnitudes do not significantly impact concentrations. Key factors instead include the amount of road salt applied, land use, groundwater recharge and the base flow index. Thus, under conditions of increased groundwater recharge, road salt is stored in groundwater rather than running off.

However, this is not good news either, as it contributes to legacy effects. The authors use a random forest model with available data to show that smaller, ecologically important streams in the study region are at risk, providing a map of potential regions of road salt lightning strikes.

Citation: Platt, L. R. C., & Dugan, H. A. (2025). Episodic salinization of midwestern and northeastern US rivers by road salt. Water Resources Research, 61, e2024WR039496. https://doi.org/10.1029/2024WR039496

—Stefan Kollet, Editor, Water Resources Research

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.

Scientists of all stripes know the value of collecting and using data to answer research questions about everything from microscopic life to Earth system processes to space physics. But what about the value of data shedding light on peers within their own research communities?

Such data can help scientists better understand the makeup of their field and help them find and connect with colleagues. Compiled into an up-to-date, worldwide directory of researchers in a given discipline, for example, they could help people search for employment opportunities, identify possible collaborators, and suggest potential reviewers for papers and proposals.

These data can also help scientists who are early in their careers or otherwise less visible within their community to gain recognition. And they can be used to identify emerging research areas and trends indicating fields that are thriving or declining—important information not only for scientists themselves but also for funding bodies, oversight committees, and policymakers.

Researchers may have ideas of the approximate size and composition of their community, but hard numbers and comprehensive information are difficult to come by.

Researchers may have ideas of the approximate size and composition of their community based on conferences they attend and journal articles they read, but hard numbers and comprehensive information are difficult to come by. Demographic surveys conducted by professional societies or funding agencies typically provide incomplete information, because not everybody responds to them, they may cover single countries only, and they’re performed infrequently.

The need for workforce demographic data was highlighted in the recent National Academies’ Decadal Survey for Solar and Space Physics, which specifically called (in recommendation 4-1) for U.S. federal agencies to fund collection of this information to help determine the state of the profession.

An underused resource for this data collection is hiding in plain sight: the body of scientific articles produced by the research community. By combining the metadata from these articles with Open Researcher and Contributor IDs (ORCIDs) that uniquely identify authors, it is possible to extract accurate, current information about researchers and their work.

HelioIndex is a new, automated online directory that uses this approach to offer an evolving snapshot of the global community in the field of solar and heliospheric physics (SHP) [Young, 2025]. HelioIndex’s methods are generalizable and can be applied as long as researcher ORCIDs are widely used in research publications, meaning it offers a model for developing similar tools in many other scientific fields.

The Who, What, Where, and How Much of SHP

SHP includes science focused on all aspects of the Sun, from its interior through its atmosphere, out into the solar wind, and all the way to the outer edge of the heliosphere. HelioIndex currently identifies more than 2,300 active SHP researchers in about 60 countries, offering information about these scientists’ geographic distribution, institutional affiliations, areas of expertise (derived from journal article keywords), and publication records.

Figure 1 offers a glimpse of how HelioIndex can be used to consider geographic trends, for example, showing the 10 countries with the most researchers included in the directory. As of July, the United States had the largest share at 29.1%, followed by China and the United Kingdom.

Fig. 1. Tallies of HelioIndex authors located in the 10 most-represented countries in July 2025 and July 2022 are shown here, along with the corresponding percentages of the total number of authors.

Updated twice a month using freely available publication data, HelioIndex always provides the most recent data, but figures from earlier dates can be used to track changes over time. Figure 1 also compares the current numbers of researchers in HelioIndex in the top 10 countries with the corresponding numbers from 3 years earlier and shows how each country’s proportional share of the SHP community has changed during that time.

From July 2022 to July 2025, China, India, and the United States, for example, saw standout increases of 42%, 39%, and 33%, respectively, in their numbers of SHP researchers. The increases contributed to these countries’ growing shares of the global total population of SHP scientists during this 3-year period. Meanwhile, growth in several European countries in the top 10 has been smaller, leading to generally decreased shares of the overall community population.

These numbers demonstrate that overall, SHP as a field is growing. The extent of growth shown in different countries may help early-career scientists to decide where to pursue their careers. The data may also be valuable to national funding bodies for assessing their countries’ competitiveness and determining whether funding levels are appropriate.

An important function of HelioIndex is to enhance the visibility of researchers and their work, especially researchers who have few opportunities for recognition.

At the other end of the scale from the top 10 countries, almost half of the countries are represented in HelioIndex with five or fewer SHP researchers. An important function of HelioIndex is to enhance the visibility of researchers and their work, especially researchers in countries with smaller SHP research communities or who have few opportunities for recognition. Greater visibility can foster new collaborations and research directions and help researchers to prosper and develop research communities in their countries.

The publication and ORCID data used in HelioIndex also enable users to better understand publishing trends within the SHP community. For example, these data allow calculation of the average annual number of first-authored, refereed (FAR) articles per person across all HelioIndex authors.

Knowing this average—currently 0.68, which equates to about two FAR papers every 3 years—is valuable for managing expectations in the field. It may reassure young researchers feeling pressure to publish frequently to advance in their careers that success does not necessarily require such a rapid publishing pace. Meanwhile, if a researcher submits a grant proposal claiming their project will yield 10 FAR papers in a 3-year period, the HelioIndex data suggest that a reviewer considering the proposal would have a right to be skeptical!

Fig. 2. The distribution of career ages—a metric estimated from the publication date of an author’s first first-authored, refereed paper—across all HelioIndex authors, as of July 2025, is currently weighted toward early-career-stage researchers.

A “career age” can also be estimated for each HelioIndex author, using the publication date of their first FAR paper as age 0. This leads to a plot of age distributions (Figure 2), with vertical lines indicating boundaries between early-, middle-, and senior-career categories. The current median career age of all authors in HelioIndex is 9.9 years.

The age distribution and calculated career ages seemingly skew toward younger ages, likely because ORCIDs came into use only in 2009. Whereas most articles published since then will be linked to authors’ ORCIDs and thus included in the HelioIndex data, older articles may be missing for some researchers. However, it is clear from the long tail of the distribution that many senior authors have manually updated their ORCID records.

A Community-Specific Resource

HelioIndex differs from other resources that contribute to professional networking in that it serves a particular research community.

HelioIndex differs from other resources that contribute to professional networking such as ORCID, Scopus, and LinkedIn in that it serves a particular research community.

The procedure for populating HelioIndex begins with scheduled, automatic queries of recent scholarly literature—as captured in NASA’s Astrophysics Data System (ADS) bibliographic database—for articles related to SHP. Articles are likely to be flagged if they, for example, reference prominent review papers, mention a major SHP observatory or spacecraft, or include certain keywords (e.g., “solar flare”).

For each article found by the queries, the names and ORCID identifiers of the authors are gathered and added to a master list of potential HelioIndex authors. As journals generally do not have standard formats for specifying author affiliations, HelioIndex uses custom software to extract institution names and countries from affiliation information through string matching. (Affiliations listed in HelioIndex are updated routinely based upon an author’s most recent publication.)

Authors are included in HelioIndex based on meeting specific keyword criteria and publication criteria. Most journals require authors to assign several keywords to their articles to indicate the area of research to which their work belongs. For inclusion in HelioIndex, it is required that at least 15% of an author’s keywords across all their published articles contain “solar,” “Sun,” or “interplanetary.” This approach has proven effective in distinguishing SHP scientists from scientists in neighboring fields such as stellar physics and magnetospheric physics.

The publication criteria include having at least one refereed article published within the past 3 years, at least one FAR paper in their career, a career age of at least 2, and at least six total points (authorship of a FAR paper counts as two points and coauthorship of a paper counts as one point). These criteria have been chosen so that HelioIndex, at least initially, primarily represents the community of SHP researchers who have earned a doctoral degree and are part of the professional workforce.

Of course, it is difficult to ensure that the directory includes everyone it should in the SHP community. Using the criteria above, for example, it is possible that some early-career researchers—who perhaps haven’t published enough research yet—may be unintentionally excluded. Such issues can be overcome, however, because as the directory’s creator (and part of the SHP community myself), I can readily assess its completeness and adjust query parameters as needed, and I can directly respond to questions about or requests to be added to HelioIndex.

Listed authors can also check their own data, identify omissions or errors, and request not to be listed by name (though in such cases, their geographic and publication data still count toward the general statistics, such as shown in Figures 1 and 2, to maintain completeness).

Scientists Finding Scientists

In addition to providing basic demographic data about the current community of SHP scientists, HelioIndex can serve many other functions. Students and other researchers exploring career options can quickly assess where scientists in the SHP community are concentrated (or not) and use the keyword data to determine with whom their expertise and interests match. They can also browse publication lists to determine scientists’ interests, activity levels, and collaborators.

HelioIndex can also be used to identify potential reviewers for a submitted journal article by matching authors’ keywords to those used in the article. This usage allows an author (or journal editor) to suggest reviewers they may otherwise not have considered, helping diversify the reviewer pool and raise the visibility of peers. This use of HelioIndex may also benefit program managers at funding agencies looking for scientists to sit on review panels.

In just the few months since HelioIndex was publicly announced, traffic to it has been robust and feedback from users has been largely positive. In September and October, for example, the site received a combined 14,651 unique visitors—higher-than-expected traffic considering the modest size of the SHP community. Individuals have commented, for example, that HelioIndex has revealed researchers and research they weren’t previously aware of, and that it helps scientists “grasp the global view of the community of Solar Physics and Heliophysics in the world,” in the words of one midcareer scientist. These early indications suggest that HelioIndex is providing valuable services to many in this community, and seemingly even to many outside it.

The basic mechanics and principles of HelioIndex can be readily applied to develop similar resources for other scientific fields, no matter their size or scope.

Beyond SHP, the basic mechanics and principles of HelioIndex can be readily applied to develop similar resources for other scientific fields, no matter their size or scope, although specific aspects of the literature queries and keyword criteria would need to be adjusted. The initial article search, for example, would need to be modified to cover relevant journals and keywords. The keyword search would need updating too; to distinguish volcanologists from geoscientists in neighboring fields, say, the keyword search could require “volcano.” (Requiring “Earth” as well could help exclude those who study volcanoes elsewhere, such as on Mars or Io.) Author publication criteria could also be revised if, for example, average publishing trends in other fields differ from those in SHP.

As the ADS database is not currently complete for the Earth sciences or other fields outside of astrophysics, an alternative source for publication data, such as Web of Science or Scopus, may be needed. Furthermore, the approach of designing custom software to pull affiliation information from articles into HelioIndex, which worked well for the relatively small SHP research community, may be more challenging for larger fields with many more institutions represented.

HelioIndex demonstrates that scientific article metadata are a rich resource that can be efficiently and effectively mined to complement the sporadic data collected through researcher surveys. With a baseline of consistent and reproducible demographic data, geographic, temporal, and subject matter trends can be identified, providing a variety of valuable information about and for research communities.

References

Young, P. R. (2025), HelioIndex: A directory of active researchers in solar and heliospheric physics, Sol. Phys., 300, 77, https://doi.org/10.1007/s11207-025-02488-y.

Author Information

Peter Young (peter.r.young@nasa.gov), NASA Goddard Space Flight Center, Greenbelt, Md.

Citation: Young, P. (2025), Shining a light on the people behind solar science, Eos, 106, https://doi.org/10.1029/2025EO250457. Published on 10 December 2025. Text not subject to copyright.
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

When exposed to environmental stressors like high ocean temperatures and excessive solar radiation, corals bleach and die. Coral reefs collapse, and their benefits—increased biodiversity, protection from coastal erosion, and local economic activity—also disappear.

Some researchers think stratospheric aerosol injection (SAI), one of the most well-studied methods of climate intervention, may help mitigate some of the effects coral bleaching when used in tandem with reductions in greenhouse gas emissions. SAI describes a process in which aerosols such as sulfur dioxide are injected into the stratosphere to reduce incoming solar radiation.

To find out whether SAI could help corals, researchers led by physical oceanographer Gouri Anil of Louisiana State University modeled future heat stress on shallow coral reefs with and without the intervention.

Anil and her fellow researchers found that SAI could help many vulnerable reefs survive through 2060, giving researchers and lawmakers time to develop more lasting solutions to mitigate climate change. Anil and the research team will present their results on 15 December at AGU’s Annual Meeting 2025 in New Orleans.

Cool Atmosphere, Warm Waters

Anil’s team calculated the heat stress that shallow equatorial reefs across the globe would experience under a moderate climate change scenario with surface sea temperature data from the United Nations’ World Conservation Monitoring Centre and the Community Earth System Model–Whole Atmosphere Community Climate Model version 6 (CESM-WACCM6).

The model used in the study is one of the best suited for this type of climate research, according to Alan Robock, a climatologist at Rutgers University who was not involved in the study. Built with data from volcanic eruptions, CESM2-WACCM6 is able to evaluate SAI as a similar release of sulfur dioxide into the atmosphere.

The modeling showed that without any intervention, nearly all the coral reefs studied would experience a fatal amount of heat stress by 2060. Certain coral species and coral reefs in central Polynesia and the tropical east Pacific, which are exposed to the most sunlight, were particularly vulnerable.

When the researchers simulated a scenario that included SAI, however, the sustainability of shallow equatorial reefs through 2060 improved. Every year, the models showed only 10% of the reefs’ area would be at risk of bleaching if SAI was implemented beginning in 2035.

SAI Side Effects

Though SAI may reduce heat stress on coral reefs, researchers said, it could have consequences that require more research to fully understand.

For example, sulfur dioxide can react with water and other substances in the atmosphere to form sulfuric acid aerosols. These aerosols eventually precipitate, Robock said. “It’s going to fall out of the atmosphere to produce acid rain, acid snow.”

“What we’re trying to do is get this information out to people who make these decisions so that they know exactly what could happen.”

Precipitation also means that regular injections of sulfur dioxide into the stratosphere, likely by specialized planes, would be required to maintain SAI’s cooling effect, Robock explained. “You need to put gas continually into the atmosphere—the amount that would be falling out at steady state.”

And while the new model points to SAI contributing to reduced heat stress on coral reefs, it doesn’t consider other factors that could affect their survival, including ocean acidification, according to Anil. The researchers are currently working on models that incorporate variables like this.

“What we’re trying to do is not advocate for climate intervention,” Anil said. “What we’re trying to do is get this information out to people who make these decisions so that they know exactly what could happen.”

—Albert Chern, Science Writer

10 December 2025: This article has been updated to correct the climate intervention method mentioned in the headline.

Citation: Chern, A. (2025), Could stratospheric aerosol injection help save corals from bleaching?, Eos, 106, https://doi.org/10.1029/2025EO250463. Published on 10 December 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.

Satellite images are revealing the scale of the destruction in Sri Lanka caused by landslides triggered by Cyclone Ditwah at the end of November 2025.

At the end of November 2025, a “weak” tropical cyclone, subsequently named Cyclone Ditwah, formed just offshore from Sri Lanka. Over the following day the storm tracked around the south and east coasts of Sri Lanka before moving northwards to dissipate on 3 December off the east coast of India. This was not a strong tropical cyclone, but it brought catastrophic rainfall to Sri Lanka, triggering extremely extensive landslides and floods.

The stats on the impact of Cyclone Ditwah on Sri Lanka are horrifying. The UNDP is reporting that 1,200 landslides were triggered and that about 20% of the island was affected by flooding. As of the time of writing, there are 639 known fatalities, with a further 203 people reported to be missing. The highest loss of life occurred in Kandy District, in the hilly centre of of the country. Many of the fatalities occurred in channelised debris flows.

The impact of the storm is complex – to study the landslides properly would require a PhD study or similar – but a quick inspection of the Planet Labs imagery of the centre of Sri Lanka illustrates the scale of the devastation. This image, collected on 7 September 2025, shows an area in the vicinity of [7.43518, 80.87898]:-

A satellite image of part the area affected by landslides triggered by Cyclone Ditwah in Sri Lanka. This image shows the area before the event. Image copyright Planet Labs, used with permission, dated 07 September 2025.

This image, collected on 30 November 2025, shows the same area after the passage of Cyclone Ditwah:-

A satellite image of part the area affected by landslides triggered by Cyclone Ditwah in Sri Lanka. This image shows the aftermath of the event. Image copyright Planet Labs, used with permission, dated 30 November 2025.

And here is a slider to compare the two images:

Image copyright Planet Labs.

And here is the post event image pasted onto the Google Earth DEM:-

A satellite image of part the area affected by landslides triggered by Cyclone Ditwah in Sri Lanka. This image shows the aftermath of the event. Image copyright Planet Labs, used with permission, dated 30 November 2025.

In the foreground is a large landslide that has started at the ridgeline. It has entrained heavily along the track, and has impacted a large area of fields at the toe of the slope. Note the channelised debris flow close by. In the background are multiple shallow landslides, many of which have reached the drainage line to generate channelised debris flows. These have been devastating downstream.

The impact of these landslides will be long lasting. I have made the point before, but it is worth reiterating, that tropical cyclones are often associated with strong winds and storm surge, but a huge proportion of the damage is actually caused by rainfall. Cyclone Ditwah was, in meteorological terms, “weak”. The images above show that this is a completely inappropriate way to characterise such storms.

Acknowledgement

Images from Planet Labs 2025 – see: https://www.planet.com/. Thanks as always for their agreement that I can use their images on this blog.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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New research reveals how the speed of ocean currents and the shape of the seabed influence the amount of heat flowing underneath Antarctic ice shelves, contributing to melting.

SummaryThe regional seismic travel-time (RSTT) model predicts travel times of regional seismic phases accounting for three-dimensional structure of the crust and the upper mantle on a global scale. Previous versions of the RSTT model have been implemented using nodes separated by ∼1° spacing across the globe. A regional-scale study using regional Pn and Pg travel times across Israel and the Middle East demonstrated that data driven, systematic grid refinement reduces travel time residuals and enhances resolution of smaller tectonic features in regions having dense ray coverage. High density Pn ray coverage in the western US, Europe, Middle East, and East Asia can likewise provide the resolution that allows systematic global grid refinement of the RSTT model. In this study, we use a large number of Pn ray paths originating from events located with an epicentral location uncertainty of 25 km (GT25) or better. We conduct targeted grid refinements at 1.0°, 0.5°, 0.25°, and 0.125° on a global scale, producing a refined RSTT model that yields a 21.6% reduction in median event location error in Europe and the Middle East, when compared with the original global RSTT model presented in Begnaud et al. (2021a). The new model also resolves finer tectonic structures in regions with high Pn ray density.

SummaryWe present and apply a pseudo trans-dimensional inversion method for 3D geometrical gravity inversion, in which the number of rock units, their geometry, and their density can vary during sampling. The method is designed for efficient exploration of the model space and to infer the presence and properties of units not directly observable but detectable with geophysical data. Sampling relies on a non-reversible Metropolis-Hastings algorithm, during which rock units can be added or removed from the model, interface geometries are perturbed using random fields, and densities are sampled from distributions informed by prior information. To visualise the space of sampled models and to aid interpretation, a workflow is proposed that combines dimensionality reduction with the clustering of models in families. The capabilities of the inversion method are evaluated using two synthetic cases. The first is a motivating example aimed at recovering an intrusion missing from the prior model. It features a horizontal layer-cake where fixed-dimensional inversion fails to adequately fit the data and sample models close to the true model, while the proposed pseudo trans-dimensional approach is much more successful. The second case investigates the recovery of two missing units and the capability to overcome prior model biases. Results show the potential of our method to infer the presence of unseen geological features such as intrusions. However, they suggest that with biased prior geological modelling, it may be challenging to infer with certainty the presence of more than two previously unknown rock units at depth.

SummaryWhen highly viscous fluids are present in a rock medium, the viscous effect of such fluids cannot be neglected in the propagation of elastic waves. In this paper, a fractional thermoporoelastic theory is newly proposed, which is a further improvement of the two-temperature generalized thermoporoelastic theory. Firstly, by introducing the Kelvin-Voigt model into the stress-strain constitutive equation, the viscous effect of highly viscous fluids is considered. Then, fractional derivatives are introduced into the heat conduction equations of the solid and fluid phase to consider the anomalous heat conduction caused by the viscous effect in rock media. Plane wave analysis method is adopted to obtain the phase velocity and attenuation factor of four longitudinal waves (P1, P2, T1, T2). Numerical results show that the introduction of fluid viscosity leads to the appearance of new relaxation peaks in the P wave at high frequencies, and the introduction of fractional derivatives causes a decrease in the phase velocity and attenuation factor of T waves. The results provide a reference for further research on the wave propagation in rock media containing highly viscous fluids.

SummaryInduced polarization (IP) effects in airborne electromagnetic (AEM) surveys have commonly been investigated in helicopter-borne systems, leaving both a bibliographic and application gap for fixed-wing configurations. This gap partly reflects the large relative number of helicopter compared to fixed wing AEM systems, but also the geometric complexity of fixed wing platforms. In these platforms, nine geometric parameters come into play: the pitch, roll, and yaw of both transmitter and receiver, plus the three-axis offsets between the coils. Shifts in these factors can distort the measured data in ways that aren’t uniquely attributable, making it hard to pinpoint whether negative recordings truly arise from IP or from geometry-related effects. The non-fixed geometry also complicates removal of the primary field, often requiring iterative processing steps that may suppress or alter spectral content linked to IP. With advances in airborne IP understanding from helicopter-borne systems, revisiting fixed-wing platforms is both timely and necessary. Part A of this two-part study addresses this issue using the TEMPEST™ fixed-wing system connecting numerical modelling with field evidence. A suite of synthetic two-layer models with variable resistivity and chargeability parameters was developed to evaluate the system’s sensitivity to polarizable structures. The experiments demonstrate that IP effects, including negative secondary field responses, can be reliably detected in fixed-wing AEM data, both in X and Z magnetic field components. The capacity of these systems to detect IP phenomena is, however, strongly dependent on the electrical conductance of the environment. For instance, both fixed-wing and helicopter-borne systems, elevated near-surface conductance enhances the amplitude of purely electromagnetic induction currents, which in turn can dominate the recorded response and obscure the comparatively weaker polarization currents. More in general, IP detectability depends on the strength of the EM response generated by induction currents flowing elsewhere, which can dominate the small reverse current flow from a polarizable target. This highlights the critical role of near-surface conductivity in controlling the expression of IP responses and underscores the need to carefully account for these factors when interpreting survey data. The synthetic results are then connected with field-scale observations from a subset of the AusAEM dataset, over 470 000 line-km of TEMPESTTM data, where negative responses align with areas of low shallow conductance, confirming the simulation results. These finding open the way to the Part B of this study, where TEMPESTTM data are inverted taking into account IP and compared with helicopter-borne results and geological information.

The Greenland and Antarctic ice sheets are highly vulnerable to global warming and scientists are being increasingly worried about the possibility of large parts of the ice sheets collapsing, if global temperatures keep on rising.

Galápagos is a living laboratory where every environmental decision matters. On Santa Cruz, the most populated island of the archipelago, freshwater is a limited and increasingly vulnerable resource due to urban growth, agricultural pressure, saltwater intrusion, and climate change. In this context, understanding how water behaves across the landscape becomes essential for water security.

What if it were possible to take a very slow geological process, one that takes thousands of years in nature, and speed it up so that it happens within hours, in order to slow the rate of global warming?

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

If you spin a bowling ball, the finger-holes will end up near the rotation axis because putting mass as far from the axis as possible minimizes energy. So, on planets –if there is a large mountain, it will end up at the equator; in physics terms, the axes of rotation and maximum inertia align.

Conversely, a planet that is very spherical will be rather unstable, so that the solid surface can move relative to the rotation axis, so-called true polar wander (TPW). Because of its slow rotation, Venus is extremely spherical; TPW can thus easily occur, driven for example by mantle convection, which is time-dependent. Furthermore, Venus’s axes of maximum inertia and rotation are offset, by about 0.5o.

In a new paper, Patočka et al. [2025] analyze the effect of convection on Venus’s axial offset and potential for TPW. They find TPW rates that are consistent with geologically-derived values, but that the resulting axial offset is much smaller than observed. Their conclusion is that atmospheric torques are likely responsible, as they probably are for the apparent variations in Venus’s rotation rate measured from Earth.

The angular offset between the rotation and maximum inertia axis as a function of time, driven by time-dependent convection. The mean value (0.0055o) is two orders of magnitude smaller than the observed value (0.5o). Convection cannot be causing this offset. Credit: Patočka et al. [2025], Figure 2e

Three spacecraft missions will soon be heading to Venus. Direct measurement of the effects predicted by the researchers are challenging, but the coupling between atmospheric dynamics and planetary rotation will surely form an important part of their investigations.

Citation: Patočka, V., Maia, J., & Plesa, A.-C. (2025). Polar motion dynamics on slow-rotating Venus: Signatures of mantle flow. AGU Advances, 6, e2025AV001976. https://doi.org/10.1029/2025AV001976

—Francis Nimmo, Editor, AGU Advances

Text © 2025. The authors. CC BY-NC-ND 3.0
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The ocean is saturated with microplastics. While we know the location of the great garbage patches, where plastic particles may accumulate below the ocean surface remains unknown. The vastness of the ocean means particle sampling data are sparse, but modeling how particles aggregate in 3D fluid flows can help determine where to look.

Wildfires pose a significant threat across the southwestern United States, due to the region's unique topography and weather conditions. Accurately identifying locations at the highest risk of a severe wildfire is critical for implementing preventive measures.

Dozens of bushfires raged over the weekend as far afield as the mid-north coast of New South Wales and Tasmania's east coast. A NSW firefighter tragically lost his life, 16 homes burned down in the NSW town of Koolewong and four in Bulahdelah, and another 19 burned down in Tasmania's Dolphin Sands.

In 2009, Rolf Hut—then a doctoral student at Delft University of Technology in the Netherlands—hacked a $40 Nintendo Wii remote, turning it into a sensor capable of measuring evaporation in a lake.

The innovation, tested in his lab’s wave generator basin, became part of Hut’s doctoral thesis and changed the course of his career. Though he’s now an associate professor at Delft, Hut considers himself a professional tinkerer and a teacher of tinkerers.

Back in 2009, Hut and a group of fellow Ph.D. students organized a session at AGU’s annual meeting in which hydrologists could demonstrate the quirky measurement devices they’d made, hacked, scavenged, or used in a manner entirely different from what manufacturers intended.

Rolf Hut from Delft University of Technology organized the AGU 2010 MacGyver session. The session included homemade devices such as a “disdrometer” for counting raindrops and a demonstration of the “rising bubble“ method of determining canal discharge. Credit: Rolf Hut

The session, “Self-Made Sensors and Unintended Use of Measurement Equipment,” was so popular that Hut organized it again the next year and the next. In addition to Hut’s remodeled Wiimote, early sessions included an acoustic rain sensor made from singing birthday card speakers, a demonstration of how to use a handheld GPS unit to measure tidal slack in estuaries, and a giant temperature-sensing pole that showed how the room heated up after the coffee break.

Since then, the endeavor has grown from a single session to many, expanded to the annual meeting of the European Geosciences Union in addition to AGU’s, and gained a new name: “People just kept calling it ‘the MacGyver session,’” Hut said.

This year, there are five MacGyver sessions, encompassing space weather, ocean environments, the geosphere, and crowdsourced science—the biggest program yet, said Chet Udell of Oregon State University, an electrical engineer and musical composer who is convening the hydrology session.

“The MacGyver sessions are a powder keg of possibilities,” Udell said. “You never know who’s gonna talk with who and what really cool collaboration or initiative could get started that way.”

The MacGyver Spirit

The term “MacGyver” originated with the 1980s television character, a resourceful secret agent known for elegantly solving complex problems with a Swiss Army knife, a few paper clips, chewing gum, or the roll of duct tape he always kept in his back pocket.

That can-do attitude is a natural fit for science, said Udell. “The MacGyver spirit is all about empowering the curiosity that drives science to also drive instrumentation.”

“Oftentimes, [scientists] come up to the barrier of, ‘I can’t ask that question because measuring this thing would be too infeasible, too complicated, too expensive, [the sensor] doesn’t exist,’” he said.

In addition to innovation—“There are a lot of people generating new science because they’ve hacked their instrumentation”—collaboration is key to the MacGyver spirit, Udell said. The ethos is less do-it-yourself (DIY) and more do-it-together. With strong links to the open-source and makerspace traditions, community and transparency are prioritized over competition and secrecy.

“No one lab has all of the expertise, the tools, and the capacity to bring these really interesting, handmade types of DIY innovation to the sciences,” Udell said.

Until recently, the MacGyver sessions were among the only places scientists and engineers could share these kinds of innovations with others. Journal articles’ methods sections typically aren’t long enough to explain exactly how to make one of these hacked or duct-taped devices.

But in 2017, the multidisciplinary, peer-reviewed journal HardwareX was launched with the aim of accelerating the distribution of low-cost, high-quality, open-source scientific hardware. Udell is an associate editor of the journal and recently published an article there with instructions on how to build a “Pied Piper” device that senses pest insects and then lures them into a trap. Citations from HardwareX can help MacGyver scientists justify time spent tinkering, he added.

The Alchemy of Serendipity

The in-person MacGyver sessions remain the heart of the movement, said Udell. There’s a certain alchemy that happens when you bring similarly geeky people together. “You know you’ve really found your community,” said Udell. “There’s a sensation that we’re all cut from the same cloth.”

“We want people to bring the physical device they’ve made and have a nerd-on-nerd discussion about that.”

There’s a reason they’re usually poster sessions, too, added Hut. “We want people to bring the physical device they’ve made and have a nerd-on-nerd discussion about that, which is a very different sort of communication than one-to-many broadcasting your awesome work.”

The format facilitates serendipitous discovery, too. “People walk by and they’re like, ‘Hey, what’s this weird device? I didn’t know you could measure that,’” said Udell. The conversation might spark an epiphany that could help someone solve a problem they’ve been wrestling with in their own research.

Kristina Collins, an electrical engineer who has convened several MacGyver sessions, said scientists and engineers from all disciplines are welcome at any of them—not just those in their own “Hogwarts House” or discipline.

“Having open-source hardware gives people a way to exchange information across different scientific cultures,” she said. “The point of Fall Meeting is to connect with the gestalt of what’s happening at the level of your field and also across fields. I really like that. I think everything interesting happens at the interface.”

Crowdsourced Science

Collins, now a research scientist at the Space Science Institute in Boulder, stumbled upon the MacGyver sessions at her first AGU annual meeting, in 2019—when she was a graduate student and the sessions were hydrology only.

At the time, she was working on making low-cost space weather station receivers for taking Doppler measurements and working with the worldwide ham radio community to deploy them—harnessing low-cost tech and crowdsourced science to gather data from the ionosphere and provide insights into the effects of solar activity on Earth.

“We named [our first receiver] the Grape because people like to name electronics after tiny fruit, and everything else was taken,” she explained (think: kiwis, limes, raspberries, blackberries, apples). “And also, it does its best work in bunches—many, many instruments [working] as a single meta instrument.”

The following year, Collins and some colleagues organized their own MacGyver session on sensors for detecting space weather. At AGU’s Annual Meeting 2025, there will be both oral and poster space weather MacGyver sessions . Collins will present an update on the Personal Space Weather Station Network and the various instruments, including Grape monitors, that make up this distributed, crowdsourced system.

For many geoscientists, the MacGyver spirit is not just a fun side quest, but a fundamental part of the scientific process, said Udell. “The questions we ask and the things that we observe are shaped by what we can measure, and this is shaped by our instrumentation,” he said.

“And so, in a way, what we make ends up making us.”

—Kate Evans (@kategevans.bsky.social), Science Writer

Citation: Evans, K. (2025), Celebrating the MacGyver spirit: Hacking, tinkering, scavenging, and crowdsourcing, Eos, 106, https://doi.org/10.1029/2025EO250460. Published on 9 December 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.

Time travelers to the Ediacaran can forget about packing a compass. Our planet’s magnetic field was remarkably weak then, and new research suggests that that situation persisted for roughly 3 times longer than previously believed.

That negligible magnetic field likely resulted in increased atmospheric oxygen levels, which in turn could have facilitated the observed growth of microscopic organisms, researchers have now concluded. These results, which will be presented at AGU’s Annual Meeting on Wednesday, 17 December, pave the way for better understanding a multitude of life-forms.

The Ediacaran period, which spans from roughly 640 million to 540 million years ago, is recognized as a time in which microscopic life began evolving into macroscopic forms. That transition in turn paved the way for the diversification of life known as the Cambrian explosion. The Ediacaran furthermore holds the honor of being one of the most recent inductees into the International Chronostratigraphic Chart, the official geologic timescale. (Last year, the Anthropocene was rejected as an addition to the International Chronostratigraphic Chart.)

A Collapsing Field, with Implications for Life

The Ediacaran was a time of magnetic tumult. An earlier study showed that our planet’s magnetic field precipitously fell from roughly modern-day values, decreasing by as much as a factor of roughly 30.

“We have this unprecedented interval in Earth’s history where the Earth’s magnetic field is collapsing.”

“We have this unprecedented interval in Earth’s history where the Earth’s magnetic field is collapsing,” said John Tarduno, a geophysicist at the University of Rochester involved in the earlier study as well as this new work.

The strength of our planet’s magnetic field has implications for life on Earth. That’s because Earth’s magnetic field functions much like a shield, protecting our planet’s atmosphere from being pummeled by a steady stream of charged particles emanating from the Sun (the solar wind). A weaker magnetic field means that more energetic particles from the solar wind can ultimately interact with the atmosphere. That influx of charged particles can alter the chemical composition of the atmosphere and allow more DNA-damaging ultraviolet radiation from the Sun to reach Earth’s surface.

There’s accordingly a strong link between Earth’s magnetic field and our planet’s ability to support life, said Tarduno. “One of the big questions we’re interested in is the relationship between Earth’s magnetic field and its habitability.”

We’re Getting Older (Rocks)

Tarduno and his colleagues previously showed that a weak magnetic field likely persisted during the Ediacaran from 591 to 565 million years ago, a span of 26 million years.

But maybe that period lasted even longer, the team surmised. To test that idea, the researchers analyzed an assemblage of 641-million-year-old anorthosite rocks from Brazil. Those rocks date to the late Cryogenian, the period immediately preceding the Ediacaran.

Back in the laboratory, the researchers extracted pieces of feldspar from the rocks. Within that feldspar, the team homed in on tiny inclusions of magnetite, a mineral that records the strength and direction of magnetic fields.

Team member Jack Schneider, a geologist at the University of Rochester, used a scanning electron microscope to observe individual needle-shaped bits of magnetite measuring just millionths of a meter long and billionths of a meter wide. “We can see the actual magnetic recorders,” said Schneider.

Working in a room shielded from Earth’s own magnetic field, Schneider measured the magnetization of feldspar crystals containing those magnetite needles. To ensure that the magnetite needles were truly reflecting Earth’s magnetic field 641 million years ago rather than a more recent magnetic field, the team focused on single-domain magnetite. A single domain refers to a region of uniform magnetization, which is much more difficult to overprint with a new magnetic field than a region magnetized in multiple directions. “We make sure that they’re good samples for us to use,” said Schneider.

Don’t Blame Reversals

The average field strength that the team recorded was consistent with zero, with an upper limit of just a couple hundred nanoteslas. “Those are the type of numbers you measure on solar system bodies today where there’s no magnetic field,” said Tarduno. For comparison, Earth’s magnetic field today is several tens of thousands of nanoteslas.

Given the weak magnetic field strengths dating to 565 million years ago and 591 million years ago and these new measurements of rocks from 641 million years ago, there might have been a roughly 70-million-year span in which Earth’s magnetic field was unusually feeble and possibly nonexistent, the team concluded.

And magnetic reversal—the periodic switching of Earth’s north and south magnetic poles—isn’t the likely culprit, the researchers suggest. It’s true that the planet’s magnetic field drops to very low levels during some parts of a magnetic reversal, but that situation persists for at most a few thousand years, said Tarduno. That’s far too short a time to show up in this dataset—the rocks that the team measured all cooled over tens of thousands of years, so the magnetic fields they recorded are an average over that time span.

Take a Deep Breath

If it’s true that Earth’s magnetic field was anomalously weak for about 70 million years, cascading effects might have helped prompt the transition from microscopic to macroscopic life, the team suggests. That shift, known as the Avalon explosion, preceded the better-known Cambrian explosion.

In particular, a weak magnetic field would have allowed the solar wind to impinge more on our planet’s atmosphere, a process that would have preferentially kicked out lighter inhabitants of the atmosphere such as hydrogen. Such a depletion of hydrogen would have, in turn, boosted the relative concentration of an important atmospheric species: oxygen.

“If you’re removing hydrogen, you’re actually increasing the oxygenation of the planet, particularly in the atmosphere and the oceans,” explained Tarduno. And because oxygen plays such a key role for so many species across the animal kingdom, it’s not too much of a stretch to imagine that the important life shift that occurred soon thereafter—miniscule creatures evolving into ones that measured centimeters or even meters in size—owes something to the invisible actor that is our planet’s magnetic field, the team concluded. “We passed a threshold that allowed things to get big,” said Tarduno.

It’s difficult to test this hypothesis by measuring ancient atmospheric oxygen levels, the team admits. (The ice cores that famously record atmospheric gases stretch back in time just about a million years, give or take.)

But this idea that the planet’s magnetic field may have triggered atmospheric changes that in turn played a role in animals growing larger makes sense, said Shuhai Xiao, a geobiologist at Virginia Tech not involved in the research. “If the oxygen concentration is low, you simply cannot grow very big.”

In the future, it will be important to fill in our knowledge of the magnetic field during the Ediacaran with more measurements, added Xiao. “One data point could change the story a lot.”

Cathy Constable, a geophysicist at the Scripps Institution of Oceanography not involved in the research, echoed that thought. “The data are sparse,” she said. But this investigation is clearly a step in the right direction, she said. “I think this is exciting work.”

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2025), The long and the weak of it—The Ediacaran magnetic field, Eos, 106, https://doi.org/10.1029/2025EO250454. Published on 9 December 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.

SummaryAcoustic signals can couple to the ground, providing an opportunity to use seismic stations to investigate airborne sources. The study of Bishop et al. (2022) used wavefield simulations in a fluid-solid medium to quantify the role of topography on the seismic (ground) recordings of a monopole source in the air. We build upon this study by linking wavefield forward modeling with the source estimation code MTUQ, which can accommodate point forces or moment tensors in a solid medium, as well as sources in the air (or water) if they are enabled by the forward-modeling solver. We perform a series of synthetic numerical experiments to demonstrate that a dipole airborne source can be estimated using ground-based receivers, even within the presence of realistic topography. We investigate the influence of receiver coverage, topography, and assumed source location on the estimated results. The established capabilities raise the prospects for future efforts to estimate dipole sources in 3D models that include heterogeneity in the air and the earth in addition to topography.

After years of little snow across the Chicago area, recent record-breaking snowfall and below-freezing temperatures might seem to contradict scientific reports of winters getting warmer. But climate change is still transforming how locals experience the changing seasons, including this fall, one of the top 10 warmest recorded in Illinois.