EOS

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

Most evidence for plate motions in the geological past comes from remnant magnetization of crustal rocks. These indicate progressive changes in latitude with respect to the magnetic dipole. While such paths are often only apparent since relative motions can be explained by continental drift, there is a component of true polar wander. Since spin organizes the convecting core’s geodynamo, polar wander implies motions of the whole Earth with respect to the planet’s rotation axis.

Vaes and van Hinsbergen [2025] provide a reanalysis of paleomagnetic data and find wander rates of approximately 3 centimeters per year, consistent with a smooth response of the moments of inertia to density anomalies shifting within mantle convection. The data cannot rule out faster motions on timescales shorter than approximately 10 million years ago, and there are uncertainties such as due to the non-unique absolute motions of the entire lithosphere with respect to the deep mantle. However, the polar motion paths appear controlled by the connected system of subduction and lowermost mantle anomalies, substantiating earlier suggestions. This system also controls core heat flow, and with it perhaps the nature of the dynamo.

Moreover, some of the deep anomalies have distinct geochemical signatures as seen from plume-sourced hotspots. The geographic links of such reservoirs with the Wilson cycle arise from polar wander as well as absolute and relative plate motions, and the associated interactions remain to be fully integrated in planetary evolution models. Such work is crucial for better estimates of paleoclimate as well as an integrative view of continental geology within the core and mantle components of the Earth system.

Citation: Vaes, B., & van Hinsbergen, D. J. J. (2025). Slow true polar wander around varying equatorial axes since 320 Ma. AGU Advances, 6, e2024AV001515. https://doi.org/10.1029/2024AV001515

—Thorsten Becker, Editor, AGU Advances

Text © 2024. 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.

Source: Geophysical Research Letters

The use of solar power is growing rapidly, especially in developing regions in the tropics, as countries work toward meeting carbon neutrality goals. But according to new research, solar power use is also accompanied by solar power shortages, or “droughts,” when demand exceeds supply for at least 3 days. Such shortages can leave millions without access to cooling or cooking abilities.

Lei et al. analyzed global supply and demand for solar power from 1984 to 2014, looking for instances of these 3-day shortages and the conditions under which they occur. Over that time, the western United States, eastern Brazil, southeastern Asia, and much of Africa each experienced at least five solar power droughts per year, and solar power droughts increased at a rate of 0.76 additional shortage per decade. This increase in rate is responsible for 29% of the weather-driven solar droughts that occurred during the 30-year period.

Solar power droughts are driven by a combination of soaring temperatures that increase demand for cooling and inclement weather or light-blocking pollution that suppresses power generation, the researchers found. Low solar power generation typically becomes a problem during periods of high cooling demand—precisely when power is most needed to keep people comfortable and safe.

The researchers also modeled how the frequency and severity of solar power droughts could change under different emissions scenarios, assuming modern infrastructure. Under Shared Socioeconomic Pathway 2-4.5, a theoretical medium-emissions pathway used in projections by the Intergovernmental Panel on Climate Change, the researchers projected that by the 2090s, solar droughts will become 7 times more frequent and 1.3 times more severe than those in the historical period. In lower-emissions scenarios, solar power droughts peak in the 2060s and then decrease because lower emissions mean fewer heat waves.

The findings illustrate the importance of adopting mitigation measures and clean energy sources to lower emissions, the authors say. Doing so, they add, could result in a “cooler and cleaner future.” (Geophysical Research Letters, https://doi.org/10.1029/2024GL112162, 2024)

—Rebecca Dzombak, Science Writer

Citation: Dzombak, R. (2025), Solar power shortages are on the rise, Eos, 106, https://doi.org/10.1029/2025EO250145. Published on 16 April 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.

Many instructors in Earth sciences and other scientific disciplines wish to engage students with the latest advances in their fields, teach cutting-edge skills, and adopt more equitable and inclusive teaching practices. The latter is an especially pressing need in the Earth sciences, which remain among the least diverse of all science, technology, engineering, and mathematics (STEM) fields [Bernard and Cooperdock, 2018].

However, achieving these goals while balancing other requirements of careers in science and science education is extraordinarily challenging. It is simply impossible to be an expert in everything. Instructional models that significantly reduce barriers to providing innovative teaching may thus be highly valuable for scientist-instructors, saving them time and increasing their effectiveness in engaging a diversity of students.

The active learning that this approach engenders lends itself to equitable and inclusive teaching practices.

The comprehensive, evidence-based approach of Observing Earth from Above offers such a model, tailored for teaching students how to access, visualize, and communicate satellite remote sensing data focused on the environment. First piloted in 2023, we developed Observing Earth from Above to provide equitable and inclusive pedagogy and content that transforms students’ knowledge, skills, and attitudes toward science and to create an environment where all students can be successful.

We applied the principles of project-based learning (PBL), in which students engage in projects as a foundational part of the curriculum. Seven principles guide the PBL approach:

• Start with a challenging problem or question
• Be subject to sustained inquiry
• Have authenticity
• Incorporate student voice and choice
• Provide opportunity for reflection
• Include critique and revision
• Conclude with a public-facing end product

The active learning that this approach engenders lends itself to equitable and inclusive teaching practices [Theobald et al., 2020]. It also supports our goal to empower students and increase their interest in science, their science identity, and their sense of self-efficacy, which are keys to enhancing diversity in STEM [Ballen et al., 2017a].

A Range of Resources

The materials developed for Observing Earth from Above focus on NASA’s Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission [Fisher et al., 2020]. ECOSTRESS, launched in 2018, provides high spatial resolution observations of land surface temperatures globally, with revisit times of every 3–5 days. These land surface temperatures are then used to derive additional data products related to evapotranspiration, water use efficiency, and evaporative stress index.

At the heart of the resources provided by Observing Earth from Above is a series of follow-along tutorials in which students learn how to access ECOSTRESS data using the free NASA AppEEARS (Application for Extracting and Exploring Analysis Ready Samples) interface, visualize those data using free and open-source geographic information system (GIS) software (Figure 1), and then effectively communicate their findings. A key goal is for students to repeatedly practice accessing and visualizing data over the span of the tutorials, creating familiarity through repetition while gradually introducing new and increasingly sophisticated skills and data products. However, each tutorial is also designed to stand alone and to require only about 30 minutes to complete, which increases the flexibility of their use.

Fig. 1. The active learning tutorial modules developed for Observing Earth from Above are designed to engage students in real-world issues while they learn, develop, and practice new skills. Click image for larger version.

We complement the tutorials with video lectures that introduce the ECOSTRESS mission, provide comprehensive overviews of the theory and algorithms for each data product, discuss current applications of these products, and consider best practices in data visualization and science communication. The slide decks used for each lecture are available for instructors to modify and adopt as needed.

Resources also include short video interviews with individuals of diverse identities who have different careers connected to remote sensing. For example, students can learn how a college student found himself in graduate school using satellite remote sensing to detect crop disease or how an air pollution specialist uses satellite remote sensing to track air quality.

Together these resources form the basis of a course with learning outcomes aligned to core competencies, including the abilities to apply the process of science, use quantitative reasoning, understand the interdisciplinary nature of science, communicate and collaborate with others, and understand how science relates to society. In addition, we provide sample syllabi, assignments, and even grading rubrics, each of which can be particularly helpful for early-career faculty developing new classes while balancing research and service demands.

Pedagogy and Curriculum in Practice

The course spans disciplines including environmental science, remote sensing, geographic information systems, data science, science communication, environmental justice, and others.

We have now taught the Observing Earth from Above materials twice to undergraduate students at Chapman University in Orange, Calif. The course spans disciplines including environmental science, remote sensing, GIS, data science, science communication, environmental justice, and others. As such, it draws students from across majors—from philosophy and business to science and engineering—engaging them in interdisciplinary thinking grounded in science. Such an approach, connecting STEM to other disciplines, can improve students’ ability to contribute to the STEM workforce [Tytler, 2020].

During twice-weekly class sessions, students first learn about a given topic through a lecture; then they work through a tutorial on that topic. Weekly homework assignments prompt students to engage further by producing a new satellite remote sensing data visualization related to the topic.

For example, students may practice working with land surface temperature data by drawing a polygon around their hometown on a map, downloading corresponding ECOSTRESS data, and producing a visualization of the hottest or coldest local surface temperatures. This “hometown temperature competition” exercise begins to connect satellite remote sensing to issues of personal relevance, which is an important motivational factor for student learning and may provide inspiration for career paths [Priniski et al., 2018]. Having students work on a series of low-stakes assignments through the course ensures that they are making progress and that they have opportunities to demonstrate what they have learned in a way that minimizes the undue stress and anxiety that often accompany high-stakes midterm and final exams [Ballen et al., 2017b].

After learning to gather and visualize land surface temperature data, students turn their attention to producing visualizations of evapotranspiration and water use efficiency in different environments, for example, comparing a field with a neighboring forest. They ultimately tackle a final project of their choosing, often using ECOSTRESS data to characterize a recent environmental event such as a heat wave or wildfire, which offers a sense of timeliness and relevance. Final projects have ranged from a study of how cooling water from power plants affects lake surface temperatures to how dam removal affects rates of evapotranspiration on neighboring riverbanks.

One student studied the surface temperatures of the school grounds in her hometown of Brea, Calif., for her final project (Figure 2). Increasing temperatures at schools represent a growing problem that has implications for students’ physical and mental health. She and another student have since expanded this work to consider every K–12 public school across Orange County, California, and are studying how school ground temperatures correlate with neighborhood demographics. This work drew interest from city government officials, who are using the information to help decide where to prioritize limited resources for repairing and renovating school grounds.

Fig. 2. This poster, produced by an undergraduate student in the Observing Earth from Above course at Chapman University as part of a final class project, compares ground surface temperatures at schools in Brea, Calif. (outlined in blue), during a heat wave. Temperature data were collected by the ECOSTRESS mission on 18 August 2023. Temperatures shown in the insets are averages for the area of that school. Credit: Gabriella Dauber

Students have expressed excitement and a sense of accomplishment at seeing the societal impacts of their work.

Students have expressed excitement and a sense of accomplishment at seeing the societal impacts of their work. In addition to the interest in the school temperatures project, other student projects are now featured on NASA’s ECOSTRESS image gallery, where they contribute to the mission’s public-facing communication efforts. Following participation in the Observing Earth from Above course, some students have focused on transitioning their class projects into publishable science, helping to advance their careers and expanding the value of the ECOSTRESS mission.

Encouraging Outcomes

The 47 students in our first two cohorts reported increases in their interest in remote sensing and science, in their sense of science identity, and in their self-efficacy to participate in science (Figure 3). One possible explanation for the reported increases may be the success of project-based learning; in semistructured interviews, students repeatedly mentioned the course’s “real-world” approach (in contrast to typical problem sets and exams):

• “The projects connected classroom theories to real-world environmental issues, which made the learning process incredibly relevant and engaging.”
• “Tackling real-world problems through projects developed my ability to analyze complex datasets and think critically about potential solutions.”
• “The hands-on GIS component was unlike anything offered in my other courses, providing not just insight but real-world skills.”

More equivocal were students’ responses about their interest in pursuing a career in science, which did not change significantly after participating in the course. A possible explanation is that about half the students across the two classes were already pursuing majors outside the natural sciences and may have been envisioning careers related to those majors.

Still, the videos featuring individuals from various careers in remote sensing were well received by many of the students, according to their interview responses. We are as content with the idea that a journalism student, for example, could engage with satellite remote sensing as part of their reporting as we are with the idea of a student changing career paths because of their participation in the course. Ultimately, the course helps build marketable skills for internships and career opportunities across disciplines—indeed, some students have subsequently been accepted for internships at NASA and other institutions.

Fig. 3. Students’ responses to survey questions collected before and after their participation in the Observing Earth from Above course indicated that their sense of science identity increased as a result of participation in the course. Earth Sciences for Everyone

Through word of mouth and conference presentations, we are engaging broader networks of educators and expanding the use of Observing Earth from Above’s learning materials to colleges and universities across the country. In these efforts, we are emphasizing empowering early-career instructors at institutions that predominantly serve students from identities that have historically been underrepresented in the geosciences.

The materials, revised on the basis of initial evaluations and assessments, are now being used by instructors at the University of California, Riverside; Murray State University; California State University, Northridge; Northern Arizona University; Wesleyan University; Colorado State University; New Jersey Institute of Technology; and Texas A&M Corpus Christi, many of which are minority-serving institutions.

Students from Chapman University; California State University, Northridge; and the University of California, Riverside, who have used the Observing Earth from Above course materials pose for a photo during a recent visit to NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Credit: Ghana Tirpude

This expansion has not been without challenges: Different schools have different academic calendars, curricular requirements, and class structures (e.g., with different meeting durations). And because adding new classes to course catalogs can be difficult and time-consuming, many instructors must blend our materials with other materials that they have to teach.

Highly modular, evidence-based materials that help address unmet needs are more flexible and likely of greater value for a broader range of educational settings than a full semester-long curriculum.

Highly modular, evidence-based materials that help address unmet needs are more flexible and likely of greater value for a broader range of educational settings than, for example, a full semester-long curriculum. Thus, we designed our lecture and tutorial content for application in 30-minute blocks to facilitate their widespread use.

Analytics data from fall 2024, the first semester that the materials were publicly available, indicate robust use. Nearly 400 users engaged with the website more than 1,500 times, and more than half of the visits were to the tutorials. Ongoing evaluation and assessment will help us understand how students with diverse identities and their instructors interact with the materials—and thus how they can be improved in the future.

Broadening diversity in the Earth sciences and expanding the relevance of the discipline in addressing environmental and societal challenges require transformative, evidence-based approaches that create equitable and inclusive opportunities for people of all identities to contribute. NASA, the U.S. Geological Survey, and other institutions have expressed strong interest in the pedagogical framework of Observing Earth from Above as one such approach and in applying it to other missions beyond ECOSTRESS. And we welcome additional interest from other programs.

We are confident that Observing Earth from Above can become a model for creating accessible educational experiences designed around Earth science missions and applications that can be used widely across classrooms to engage a new generation of students.

Acknowledgment

Observing Earth from Above was developed with support from NASA ECOSTRESS mission grant 80NSSC23K0309.

References

Ballen, C. J., et al. (2017a), Enhancing diversity in undergraduate science: Self-efficacy drives performance gains with active learning, CBE Life Sci. Educ., 16(4), ar56, https://doi.org/10.1187/cbe.16-12-0344.

Ballen, C. J., S. Salehi, and S. Cotner (2017b), Exams disadvantage women in introductory biology, PLOS One, 12(10), e0186419, https://doi.org/10.1371/journal.pone.0186419.

Bernard, R. E., and E. H. G. Cooperdock (2018), No progress on diversity in 40 years, Nat. Geosci., 11(5), 292–295, https://doi.org/10.1038/s41561-018-0116-6.

Fisher, J. B., et al. (2020), ECOSTRESS: NASA’s next generation mission to measure evapotranspiration from the International Space Station, Water Resour. Res., 56(4), e2019WR026058, https://doi.org/10.1029/2019WR026058.

Priniski, S. J., C. A. Hecht, and J. M. Harackiewicz (2018), Making learning personally meaningful: A new framework for relevance research, J. Exp. Educ., 86(1), 11–29, https://doi.org/10.1080/00220973.2017.1380589.

Theobald, E. J., et al. (2020), Active learning narrows achievement gaps for underrepresented students in undergraduate science, technology, engineering, and math, Proc. Natl. Acad. Sci. U. S. A., 117(12), 6,476–6,483, https://doi.org/10.1073/pnas.1916903117.

Tytler, R. (2020), STEM education for the twenty-first century, in Integrated Approaches to STEM Education: An International Perspective, edited by J. Anderson and Y. Li, pp. 21–43, Springer, Cham, Switzerland, https://doi.org/10.1007/978-3-030-52229-2_3.

Author Information

Gregory R. Goldsmith (goldsmit@chapman.edu), Schmid College of Science and Technology, Chapman University, Orange, Calif.; Monae Verbeke, Institute for Learning Innovation, Beaverton, Ore.; Jeremy Forsythe, Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff; and Joshua B. Fisher, Schmid College of Science and Technology, Chapman University, Orange, Calif.

Citation: Goldsmith, G. R., M. Verbeke, J. Forsythe, and J. B. Fisher (2025), A diverse new generation of scientists observes Earth from above, Eos, 106, https://doi.org/10.1029/2025EO250111. Published on 16 April 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.

This story was originally published by Knowable Magazine.

To the people of Mbiabet Esieyere and Mbiabet Udouba in Nigeria’s deep south, sundown would mean children doing their homework by the glow of kerosene lamps, and the faint thrum of generators emanating from homes that could afford to run them. Like many rural communities, these two villages of fishermen and farmers in the community of Mbiabet, tucked away in clearings within a dense palm forest, had never been connected to the country’s national electricity grid.

Most of the residents had never heard of solar power either. When, in 2021, a renewable-energy company proposed installing a solar “mini-grid” in their community, the villagers scoffed at the idea of the sun powering their homes. “We didn’t imagine that something [like this] can exist,” says Solomon Andrew Obot, a resident in his early 30s.

Solomon Andrew Obot poses for a portrait at the mini-grid site. Andrew Obot has lived in Mbiabet Esieyere his whole life. Before the arrival of the mini-grids, he acted as vice youth president. Today, he is the site manager. Credit: Victoria Uwemedimo

The small installation of solar panels, batteries and transmission lines proposed by the company Prado Power would service 180 households in Mbiabet Esieyere and Mbiabet Udouba, giving them significantly more reliable electricity for a fraction of the cost of diesel generators. Village leaders agreed to the installation, though many residents remained skeptical. But when the panels were set up in 2022, lights blinked on in the brightly painted two-room homes and tan mud huts dotted sparsely through the community. At a village meeting in September, locals erupted into laughter as they recalled walking from house to house, turning on lights and plugging in phone chargers. “I [was] shocked,” Andrew Obot says.

Like many African nations, Nigeria has lagged behind Global North countries in shifting away from planet-warming fossil fuels and toward renewable energy. Solar power contributes just around 3 percent of the total electricity generated in Africa — though it is the world’s sunniest continent — compared to nearly 12 percent in Germany and 6 percent in the United States.

“Nigeria is actually like a poster child for mini-grid development across Africa.”

At the same time, in many African countries, solar power now stands to offer much more than environmental benefits. About 600 million Africans lack reliable access to electricity; in Nigeria specifically, almost half of the 230 million people have no access to electricity grids. Today, solar has become cheap and versatile enough to help bring affordable, reliable power to millions — creating a win-win for lives and livelihoods as well as the climate.

That’s why Nigeria is placing its bets on solar mini-grids — small installations that produce up to 10 megawatts of electricity, enough to power over 1,700 American homes — that can be set up anywhere. Crucially, the country has pioneered mini-grid development through smart policies to attract investment, setting an example for other African nations.

Thanks to its sunny, equatorial position, the African continent has an immense potential for solar power, shown here in kilowatt-hours. However, solar power contributes less than 3 percent of the electricity generated in Africa. Credit: Knowable Magazine, adapated from Solar Resource Map, CC BY-SA 4.0. Click image for larger version.

Nearly 120 mini-grids are now installed, powering roughly 50,000 households and reaching about 250,000 people. “Nigeria is actually like a poster child for mini-grid development across Africa,” says energy expert Rolake Akinkugbe-Filani, managing director of EnergyInc Advisors, an energy infrastructure consulting firm.

Though it will take more work — and funding — to expand mini-grids across the continent, Nigeria’s experience demonstrates that they could play a key role in weaning African communities off fossil-fuel-based power. But the people who live there are more concerned with another, immediate benefit: improving livelihoods. Affordable, reliable power from Mbiabet’s mini-grid has already supercharged local businesses, as it has in many places where nonprofits like Clean Technology Hub have supported mini-grid development, says Ifeoma Malo, the organization’s founder. “We’ve seen how that has completely transformed those communities.”

The African energy transition takes shape

Together, Africa’s countries account for less than 5 percent of global carbon dioxide emissions, and many experts, like Malo, take issue with the idea that they need to rapidly phase out fossil fuels; that task should be more urgent for the United States, China, India, the European countries and Russia, which create the bulk of emissions. Nevertheless, many African countries have set ambitious phase-out goals. Some have already turned to locally abundant renewable energy sources, like geothermal power from the Earth’s crust, which supplies nearly half of the electricity produced in Kenya, and hydropower, which creates more than 80 percent of the electricity in the Democratic Republic of Congo, Ethiopia and Uganda.

But hydropower and geothermal work only where those resources naturally exist. And development of more geographically versatile power sources, like solar and wind, has progressed more slowly in Africa. Though solar is cheaper than fossil-fuel-derived electricity in the long term, upfront construction costs are often higher than they are for building new fossil-fuel power plants.

Getting loans to finance big-ticket energy projects is especially hard in Africa, too. Compared to Europe or the United States, interest rates for loans can be two to three times higher due to perceived risks — for instance, that cash-strapped utility companies, already struggling to collect bills from customers, won’t be able to pay back the loans. Rapid political shifts and currency fluctuations add to the uncertainty. To boot, some Western African nations such as Nigeria charge high tariffs on importing technologies such as solar panels. “There are challenges that are definitely hindering the pace at which renewable energy development could be scaling in the region,” says renewable energy expert Tim Reber of the Colorado-based US National Renewable Energy Laboratory.

Some African countries are beginning to overcome these barriers and spur renewable energy development, notes Bruno Merven, an expert in energy systems modeling at the University of Cape Town in South Africa, coauthor of a look at renewable energy development in the Annual Review of Resource Economics. Super-sunny Morocco, for example, has phased out subsidies for gasoline and industrial fuel. South Africa is agreeing to buy power from new, renewable infrastructure that is replacing many coal plants that are now being retired.

More than 500 million Africans lack access to electricity, and where there is electricity, much of it comes from fossil fuels. Countries are taking different approaches to bring more renewable energy into the mix. Nigeria is focusing on mini-grids, which are especially useful in areas that lack national electricity grids. Morocco and South Africa are building large-scale solar power installations, while Kenya and the Democratic Republic of the Congo are making use of local renewable energy sources like geothermal and hydropower, respectively. Credit: Knowable Magazine, featuring information from the IEA Africa Energy Outlook 2019. Click image for larger version.

Nigeria, where only about a quarter of the national grid generates electricity and where many turn to generators for power, is leaning on mini-grids — since expanding the national grid to its remote communities, scattered across an area 1.3 times the size of Texas, would cost a prohibitive amount in the tens of billions of dollars. Many other countries are in the same boat. “The only way by which we can help to electrify the entire continent is to invest heavily in renewable energy mini-grids,” says Stephen Kansuk, the United Nations Development Program’s regional technical advisor for Africa on climate change mitigation and energy issues.

Experts praise the steps Nigeria has taken to spur such development. In 2016, the country’s Electricity Regulatory Commission provided legal guidelines on how developers, electricity distribution companies, regulators and communities can work together to develop the small grids. This was accompanied by a program through which organizations like the World Bank, the Global Energy Alliance for People and Planet, Bezos Earth Fund and the Rockefeller Foundation could contribute funds, making mini-grid investments less financially risky for developers.

Solar power was also made more attractive by a recent decision by Nigerian President Bola Ahmed Tinubu to remove a long-standing government subsidy on petroleum products. Fossil-fuel costs have been soaring since, for vehicles as well as the generators that many communities rely on. Nigeria has historically been Africa’s largest crude oil producer, but fuel is now largely unaffordable for the average Nigerian, including those living in rural areas, who often live on less than $2 a day. In the crude-oil-rich state of Akwa Ibom, where the Mbiabet villages are located, gasoline was 1,500 naira per liter (around $1) at the time of publishing. “Now that subsidies have come off petrol,” says Akinkugbe-Filani, “we’re seeing a lot more people transition to alternative sources of energy.”

Mini-grids take off

The women, it turned out, were fascinated by the technology and how it could help them, especially at night — to fetch water from streams, to use the bathroom and to keep their children safe from snakes.

To plan a mini-grid in Nigeria, developers often work with government agencies that have mapped out ideal sites: sunny places where there are no plans to extend the national grid, ensuring that there’s a real power need.

The next step is getting communities on board, which can take months. Malo recalls a remote Indigenous village in the hills of Adamawa state in Nigeria’s northeast, where locals have preserved their way of life for hundreds of years and are wary of outsiders. Her team had almost given up trying to liaise with reluctant male community leaders and decided to try reaching out to the women. The women, it turned out, were fascinated by the technology and how it could help them, especially at night — to fetch water from streams, to use the bathroom and to keep their children safe from snakes. “We find that if we convince them, they’re able to go and convince their husbands,” Malo says.

The Mbiabet community took less convincing. Residents were drawn to the promise of cheap, reliable electricity and its potential to boost local businesses.

Like many other mini-grids, the one in Mbiabet benefited from a small grant, this one from the Rocky Mountain Institute, a US-based nonprofit focused on renewable energy adoption. The funds allowed residents to retain 20 percent ownership of the mini-grid and reduced upfront costs for Prado Power, which built the panels with the help of local laborers.

On a day in late September, it’s a sunny afternoon, though downpours from the days before have made their imprint on the ground. There are no paved roads and today, the dirt road leading through the tropical forest into the cluster of villages is unnavigable by car. At one point, we build an impromptu bridge of grass and vegetation across a sludgy impasse; the last stretch of the journey is made on foot. It would be costly and labor-intensive to extend the national grid here.

Mbiabet is so remote that no paved roads lead to it. But an unusual sight reveals that it is more “connected” than most communities like it — there are power lines threaded through the bush. Credit: Victoria Uwemedimo

Palm trees give way to tin roofs propped up by wooden poles, and Andrew Obot is waiting at the meeting point. He was Mbiabet’s vice youth president when Prado Power first contacted the community; now he’s the site manager. He steers his okada — a local motorbike — up the bumpy red dirt road to go see the solar panels.

Along the way, we see transmission lines threading through thick foliage. “That’s the solar power,” shouts Andrew Obot over the drone of the okada engine. All the lines were built by Prado Power to supply households in the two villages.

We enter a grassy clearing where three rows of solar panels sit behind wire gates. Collectively, the 39 panels have a capacity of over 20 kilowatts — enough to power just one large, energy-intensive American household but more than enough for the lightbulbs, cooker plates and fans in the 180 households in Mbiabet Esieyere and Mbiabet Udouba.

Whereas before, electricity was more conservatively used, now it is everywhere. An Afrobeats tune blares from a small barbershop on the main road winding through Mbiabet Esieyere. Inside, surrounded by walls plastered with shiny posters of trending hairstyles — including a headshot of popular musician Davido with the tagline “BBC — Big Boyz Cutz” — two young girls sit on a bench near a humming fan, waiting for their heads to be shaved.

The salon owner, Christian Aniefiok Asuquo, started his business two years ago when he was 16, just before the panels were installed. Back then, his appliances were powered by a diesel generator, which he would fill with 2,000 naira worth (around $1.20) of fuel daily. This would last around an hour. Now, he spends just 2,000 naira a month on electricity. “I feel so good,” he says, and his customers, too, are happy. He used to charge 500 naira ($0.30) per haircut, but now charges 300 naira ($0.18) and still makes a profit. He has more customers these days.

For many Mbiabet residents, “it’s an overall boost in their economic development,” says Suleiman Babamanu, the Rocky Mountain Institute’s program director in Nigeria. Also helping to encourage residents to take full advantage of their newly available power is the installation of an “agro-processing hub,” equipped with crop-processing machines and a community freezer to store products like fish. Provided by the company Farm Warehouse in partnership with Prado Power, the hub is leased out to locals. It includes a grinder and fryer to process cassava — the community’s primary crop — into garri, a local food staple, which many of the village women sell to neighboring communities and at local markets.

The women are charged around 200 naira ($0.12) to process a small basin of garri from beginning to end. Sarah Eyakndue Monday, a 24-year-old cassava farmer, used to spend three to four hours processing cassava each day; it now takes her less than an hour. “It’s very easy,” she says with a laugh. She produces enough garri during that time to earn up to 50,000 naira ($30.25) a week — almost five times what she was earning before.

“Everywhere is … brighter than before.”

Prado Power also installed a battery system to save some power for nighttime (there’s a backup diesel generator should batteries become depleted during multiple overcast days). That has proved especially valuable to women in Mbiabet Esieyere and Mbiabet Udouba, who now feel safer. “Everywhere is … brighter than before,” says Eyakndue Monday.

Other African communities have experienced similar benefits, according to Renewvia Energy, a US-based solar company. In a recent company-funded survey, 2,658 Nigerian and Kenyan households and business owners were interviewed before and after they got access to Renewvia’s mini-grids. Remarkably, the median income of Kenyan households had quadrupled. Instead of spending hours each day walking kilometers to collect drinking water, many communities were able to install electricity-powered wells or pumps, along with water purifiers.

“With all of that extra time, women in the community were able to either start their own businesses or just participate in businesses that already exist,” says Renewvia engineer Nicholas Selby, “and, with that, gain some income for themselves.”

Navigating mini-grid challenges

Solar systems require regular maintenance — replacing retired batteries, cleaning, and repairing and addressing technical glitches over the 20- to 25-year lifetime of a panel. Unless plans for care are built into a project, they risk failure. In some parts of India, for example, thousands of mini-grids installed by the government in recent decades have fallen into disrepair, according to a report provided to the Washington Post. Typically, state agencies have little long-term incentive to maintain solar infrastructure, Kansuk says.

Kansuk says this is less likely in situations where private companies that make money off the grids help to fund them, encouraging them to install high-quality devices and maintain them. It also helps to train locals with engineering skills so they can maintain the panels themselves — companies like Renewvia have done this at their sites. Although Prado Power hasn’t been able to provide such training to locals in Mbiabet or their other sites, they recruit locals like Andrew Obot to work as security guards, site managers and construction workers.

Over the longer term, demographic shifts may also leave some mini-grids in isolated areas abandoned — as in northern Nigeria, for instance, where banditry and kidnapping are forcing rural populations toward more urban settings. “That’s become a huge issue,” Malo says. Partly for this reason, some developers are focusing on building mini-grids in regions that are less prone to violence and have higher economic activity — often constructing interconnected mini-grids that supply multiple communities.

Eventually, those close enough to the national grid will likely be connected to the larger system, says Chibuikem Agbaegbu, a Nigeria-based climate and energy expert of the Africa Policy Research Institute. They can send their excess solar-sourced electricity into the main grid, thus making a region’s overall energy system greener and more reliable.

The biggest challenge for mini-grids, however, is cost. Although they tend to offer cheaper, more reliable electricity compared to fossil-fuel-powered generators, it is still quite expensive for many people — and often much more costly than power from national grids, which is frequently subsidized by African governments. Costs can be even higher when communities sprawl across large areas that are expensive to connect.

Mini-grid companies have to charge relatively high rates in order to break even, and many communities may not be buying enough power to make a mini-grid worthwhile for the developers — for instance, Kansuk says, if residents want electricity only for lighting and to run small household appliances.

“For you to be able to really transform lives in rural communities, you need to be able to improve the business viability — both for the mini-grid and for the community.”

Kansuk adds that this is why developers like Prado Power still rely on grants or other funding sources to subsidize construction costs so they can charge locals affordable prices for electricity. Another solution, as evidenced in Mbiabet, is to introduce industrial machinery and equipment in tandem with mini-grids to increase local incomes so that people can afford the electricity tariffs.

“For you to be able to really transform lives in rural communities, you need to be able to improve the business viability — both for the mini-grid and for the community,” says Babamanu. The Rocky Mountain Institute is part of an initiative that identifies suitable electrical products, from cold storage to rice mills to electric vehicle chargers, and supports their installation in communities with the mini-grids.

Spreading mini-grids across the continent

Energy expertsbelieve that these kinds of solutions will be key for expanding mini-grids across Africa. Around 60 million people in the continent gained access to electricity through mini-grids between 2009 and 2019, in countries such as Kenya, Tanzania and Senegal, and the United Nations Development Program is working with a total of 21 African countries, Kansuk says, including Mali, Niger and Somalia, to incentivize private companies to develop mini-grids there.

But it takes more than robust policies to help mini-grids thrive. Malo says it would help if Western African countries removed import tariffs for solar panels, as many governments in Eastern Africa have done. And though Agbaegbu estimates that Nigeria has seen over $900 million in solar investments since 2018 — and the nation recently announced $750 million more through a multinationally funded program that aims to provide over 17.5 million Nigerians with electricity access — it needs more. “If you look at what is required versus what is available,” says Agbaegbu, “you find that there’s still a significant gap.”

Many in the field argue that such money should come from more industrialized, carbon-emitting countries to help pay for energy development in Global South countries in ways that don’t add to the climate problem; some also argue for funds to compensate for damages caused by climate impacts, which hit these countries hardest. At the 2024 COP29 climate change conference, wealthy nations set a target of $300 billion in annual funding for climate initiatives in other countries by 2035 — three times more than what they had previously pledged. But African countries alone need an estimated 200 billion per year by 2030 to meet their energy goals, according to the International Energy Agency.

Meanwhile, Malo adds, it’s important that local banks in countries like Nigeria also invest in mini-grid development, to lessen dependence on foreign financing. That’s especially the case in light of current freezes in USAID funding, she says, which has resulted in a loss of money for solar projects in Nigeria and other nations.

With enough support, Reber says, mini-grids — along with rooftop and larger solar projects — could make a sizable contribution to lowering carbon emissions in Africa. Those who already have the mini-grids seem convinced they’re on the path toward a better, economically richer future, and Babamanu knows of communities that have written letters to policymakers to express their interest.

Eyakndue Monday, the cassava farmer from Mbiabet, doesn’t keep her community’s news a secret. Those she has told now come to her village to charge their phones and watch television. “I told a lot of my friends that our village is … better because of the light,” she says. “They were just happy.”

—Victoria Uwemedimo and Katrina Zimmer, Knowable Magazine

This article originally appeared in Knowable Magazine, a nonprofit publication dedicated to making scientific knowledge accessible to all. Sign up for Knowable Magazine’s newsletter.

Read the original article here.

Each year in early March, when summer turns to fall in the Southern Hemisphere, New Zealand glaciologists gather at an airfield in Queenstown to embark on a predawn flight along the spine of the Southern Alps.

For hours, they twist in the Cessna’s narrow seats to train cameras on glaciers clinging to mountaintops. The images capture the glaciers’ vanishing contours and the shifting snowline—the demarcation between the remains of the winter snowpack and exposed glacial ice.

“It’s like a bank account,” said Andrew Lorrey, a climate scientist at the National Institute of Water and Atmospheric Research who has been coordinating the surveys for 16 years. “If we put in the same amount of snow in winter as we’re taking out in summer, the glacier would be in balance, melting at its terminus but advancing downhill due to gravity and replenishing the ice that’s lost.”

But the surveys, which have been running since 1977, show that summer melt now far exceeds winter snowfall and “we’re seeing the glaciers’ terminus and sides, the whole body, diminishing.”

New Zealand has lost more than a third of its glacial ice and the archipelago ranks third globally—after central Europe and the Caucasus—in the proportion of ice lost to rising temperatures, according to findings published in Nature by the first comprehensive global Glacier Mass Balance Intercomparison Exercise (GlaMBIE).

Global Assessment of Glacial Retreat

The project assessed observations from 35 international teams, with a goal of reconciling all methods used to track glacial mass changes. These methodologies range from in situ measurements (in which scientists stud individual glaciers with ablation stakes to record their shrinkage) to various satellite-borne sensors (which use optical, radar, laser, and gravimetry technologies to track changes in glacial surface elevation).

Bringing all these methodologies together, the GlaMBIE team produced a time series of global glacial mass change between 2000 and 2023, showing that collectively, the world’s glaciers lost 5% of their total volume. “This may not seem much,” said Michael Zemp, GlaMBIE project leader and director of the World Glacier Monitoring Service at the University of Zürich. But it means an annual global loss of 273 billion tonnes (301 billion tons) of ice.

“The ice lost each year amounts to the water intake of the entire global population in 30 years.”

“To put this in perspective,” Zemp said, “the ice lost each year amounts to the water intake of the entire global population in 30 years, assuming 3 liters per person a day.”

Andrew Shepherd, an Earth scientist at Northumbria University who was not involved in this project but has led a similar assessment of mass loss from polar ice sheets, welcomed the authoritative standardized framework provided by GlaMBIE.

Reconciling the different methodologies is important because “climate change isn’t smooth,” Shepherd said. Short-term in situ measurements can deliver contrasting results and each satellite technique has its strengths and weaknesses, but “bringing all methods together leads to a clearer picture of total ice loss,” he noted.

Although all areas experienced ice loss, the GlaMBIE results show significant differences between regions, ranging from 1.5% ice loss in the Antarctic to 39% in central Europe.

This map displays glacier mass changes from 2000 to 2023 as percentage loss (red slice in the pie chart) based on total glacier mass in 2000 (size of the pie chart). The colored stripes under each pie chart represent annual specific mass changes (in meter water equivalent) for a combined estimate (indicated with an asterisk) together with combined results from digital elevation model differencing and glaciological observations (Dg), altimetry (A), and gravimetry (G). Regional results are represented for hydrological years, that is, running from 1 October to 30 September in the Northern Hemisphere, 1 April to 31 March in the Southern Hemisphere, and over the calendar year in the low latitudes. Global results are aggregated for calendar years. Credit: The GlaMBIE Team. Community estimate of global glacier mass changes from 2000 to 2023. Credit: The GlaMBIE Team, 2025, https://doi.org/10.1038/s41586-024-08545-z

The largest overall contribution to ice loss (22%) comes from Alaska, said Caitlyn Florentine, a research physical scientist with the U.S. Geological Survey in Bozeman, Mont., and a GlaMBIE member.

Alaska, like the Canadian Arctic and Greenland, has enormous volumes of ice. But the relatively low elevation and latitude of Alaskan glaciers meant that these ice fields “were the biggest contributor to sea level rise [from glaciers] in the first 2 decades of this century and are projected to continue [to be] until 2100,” Florentine explained.

“Every centimeter of sea level rise exposes another 2 million people to annual flooding somewhere on our planet.”

The GlaMBIE results also revealed clear evidence of increasing melt rates, with a 36% jump during the second half of the study period, from 2012 to 2023. Mountain glaciers hold enough water to raise sea level by 32 centimeters if all were to melt. The ice that has already been lost from the world’s mountains has contributed 18% more to sea level rise than the loss from the Greenland Ice Sheet and more than twice the loss from the Antarctic Ice Sheet.

“Even small amounts of sea level rise matter, because it leads to more frequent coastal flooding,” Shepherd said. “Every centimeter of sea level rise exposes another 2 million people to annual flooding somewhere on our planet.”

Zemp hopes to focus future work on assessing how glacier melt affects seasonal runoff, and that requires ongoing access to satellite data and higher-resolution remote sensing techniques. As some satellites and sensors approach the end of their missions, he’s concerned about continuing the study. “If we are left without open access to high-resolution stereo imaging missions with a global coverage, we’d be blind to these changes,” he said.

Gone This Century

In addition to the ice sheets in Antarctica and Greenland, there are more than 275,000 glaciers—or crystal cones, as Zemp calls them—in mountain ranges from the tropics to the polar regions. Only about 500 are monitored up close.

One is Brewster Glacier in New Zealand, which Te Herenga Waka–Victoria University of Wellington glaciologist Lauren Vargo visits regularly. She drills ablation stakes into the ice in spring and retrieves their exposed parts in fall. In the 8 years between 2016 and 2024, she’s helped document that the glacier has shrunk by 24% and lost 17 meters in height.

New Zealand’s Brewster Glacier has shrunk by 24% in the 8 years between 2016 and 2024. Credit: Lauren Vargo

The retreat made Vargo’s latest visit, in March, physically taxing, she said. “The more melt that happens, the more stakes you have to collect,” she explained. “I don’t think I could have carried any more stakes.”

Many glaciers will not survive this century, Zemp said. Among these is one of his favorites, Oberaargletscher at Grimselpass in Switzerland, which Zemp has studied for almost a quarter of a century and, more recently, began visiting with his sons.

Oberaargletscher will be gone by 2050, regardless of any cuts to carbon emissions, Zemp said. While the retreat is “interesting to witness as a scientist,” he continued, “I am deeply sad that my sons and their generation will lose this fantastic glacier.”

—Veronika Meduna (@veronikameduna.bsky.social), Science Writer

Citation: Meduna, V. (2025), First global comparison of glacier mass change: They’re all melting, and fast, Eos, 106, https://doi.org/10.1029/2025EO250141. Published on 15 April 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.

Source: Journal of Geophysical Research: Biogeosciences

At the uppermost reaches of stream networks, headwaters dry up during the summer, then burst back into existence when spring brings rain. These nonperennial headwater streams are individually small, but collectively, they make up most of the length of global stream networks, and their chemistry is consequential for downstream waters.

As Earth warms, headwater streams are spending more time dried up and less time running. Zarek et al. investigated how increased dry time affects the nitrogen dynamics of streams throughout a watershed. To do so, they installed 21 sensors throughout a stream network in Alabama’s Talladega National Forest to collect information about stream drying and nitrogen content over the course of a year. They complemented these frequent measurements, taken every 15 minutes, with manual measurements taken during six campaigns across seven sites in the watershed.

The researchers expected that increased streamflow during springtime would wash nutrients downstream and raise nitrogen levels at the outlet of the stream network. Instead, they observed the opposite: When headwater streams increased streamflow, nitrogen concentrations at the outlet decreased. That could be because stream biota, such as riparian plants, in need of nutrients took up more nitrogen, keeping it from running downstream. Aquifer recharging in the spring, as a result of stream rewetting, may also spur chemical reactions that remove nitrogen and prevent its transport downstream.

The researchers also found that both nitrogen concentrations in the watershed and nitrogen removal rates were highest during the period when headwater streams were drying, findings they noted were “surprising.” They hypothesize that the high nitrogen concentrations could be because low streamflow creates ideal conditions for microbial activity that raises the nitrogen content of the water. The same conditions, they suggest, could also be ideal for allowing other microbes to remove nitrogen.

Position within the stream network was not a strong predictor of nitrogen concentrations, the researchers found. That observation suggests that many qualities of streams influence nitrogen dynamics and lead to heterogeneous nitrogen concentrations throughout the system. Their results highlight the need for additional spatially distributed stream monitoring, the researchers write. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2024JG008522, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), The “surprising” effect of drying headwaters on nitrogen dynamics, Eos, 106, https://doi.org/10.1029/2025EO250142. Published on 15 April 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.

Source: AGU Advances

The 2023 Kahramanmaraş earthquake struck southern Türkiye and Syria along the East Anatolian Fault. The magnitude 7.8 quake and its magnitude 7.5 aftershock devastated the region, killing tens of thousands of people and destroying hundreds of thousands of buildings.

Before the earthquake, seismologists warned that the area was ripe for a major seismic event. The region sits at the junction of the Anatolian, Arabian, and Eurasian plates and is rife with faults. In the years since the quake, scientists have been researching the seismic links between the main shock and aftershocks that struck across hundreds of kilometers.

Luo et al. used interferometric synthetic aperture radar on imagery collected by the Sentinel-1 satellite and Advanced Land Observing Satellite-2 (ALOS-2) to measure changes in land surface elevation following the earthquake.

The analysis identified eight areas outside the main rupture zone that saw localized changes in surface elevation triggered by the 2023 earthquake sequence, none of which were associated with known, discrete seismic events.

Of these events, four were typical aseismic events. Aseismic events involve geologic movement without earthquakes. For instance, in a slow-slip event, energy is released along a fault line gradually, over the course of weeks or months, causing land to move in a way that is imperceptible without scientific instruments.

Two others were seismic events—in which energy along a fault line was released abruptly—that were masked by the main earthquake’s seismic waves.

The remaining two events stood out. Dubbed “silent” events, the quakes—both greater than magnitude 5—did not produce local aftershocks or radiate detectable seismic waves as a typical earthquake would. The amount of stress along the fault did drop significantly after the tremor, however, similar to how it would in a regular earthquake. The authors suggest the aseismic events with a high drop in stress represent a previously unidentified transitional mode between regular earthquakes and slow-slip events.

Though more reviews of recent earthquakes are needed to determine whether these silent events were outliers, the findings could represent a missing slip type in models, with significant implications for scientists’ understanding of earthquake physics. The results also reveal new insights into seismic hazards in the vicinity of large, deadly quakes. (AGU Advances, https://doi.org/10.1029/2024AV001457, 2025)

—Aaron Sidder, Science Writer

Citation: Sidder, A. (2025), Türkiye-Syria temblors reveal missing piece in earthquake physics, Eos, 106, https://doi.org/10.1029/2025EO250144. Published on 15 April 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.

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

Water flowed on ancient Mars, but the timing, duration, effects, and exact nature of liquid water systems at or near the surface are still debated by planetary scientists. One setting where water could have been prevalent on early Mars is hydrothermal circulation—that is, the heat-driven circulation of warm water within the crust—under craters.

Mittelholz et al. [2025] test the presence and duration of hydrothermal systems under impact craters on early Mars by considering the effects that those systems would have on geophysical parameters of the Martian crust that we can observe today. In particular, the authors focus on the concepts that hydrothermal circulation would efficiently cool the local crust, hindering the deformation of craters that occurs when rocks are warm, and would alter the magnetization of the crust through chemical processes associated with the extensive water-rock interaction triggered by hydrothermal systems. The authors use sophisticated data analyses and numerical models to show that the orbital gravity and magnetic data collected by Mars-orbiting spacecraft are consistent with these effects of hydrothermal circulation in several regions on Mars.

The study finds that the water-rock interactions associated with hydrothermal circulation were not only present on early Mars, but long-lasting. Additionally, the study demonstrates how an interdisciplinary approach—tying together geophysics and geochemistry, gravity and magnetism, crust and core—can be used to address big picture questions about planetary habitability. The authors argue that a dedicated gravity mission in Martian orbit or regional magnetic studies conducted near the surface could further test these ideas.

Citation: Mittelholz, A., Moorkamp, M., Broquet, A., & Ojha, L. (2025). Gravity and magnetic field signatures in hydrothermally affected regions on Mars. Journal of Geophysical Research: Planets, 130, e2024JE008832. https://doi.org/10.1029/2024JE008832  

—Michael M. Sori, Associate Editor, JGR: Planets

Text © 2024. The authors. CC BY-NC-ND 3.0
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The locations of drainage divides determine how water flows across a landscape. Now, a new study has revealed how quickly these features can migrate when a region’s normally dry climate gets a little wetter.

Researchers used a combination of field observations, sediment dating, and numerical modeling to show how a river system in Israel’s Negev Desert has made sudden shifts in response to known wet periods. Drainage divides that migrated at an average rate of 1.1 kilometers (0.7 mile) per million years over the studied interval stalled and picked up speed in step with known shifts in the region’s climate.

“To my knowledge, this is the first study that directly measures rates of drainage divide migration,” said Mikaël Attal, a geomorphologist at the University of Edinburgh in Scotland who was not involved in the research. “This is important because drainage migration can have implications for understanding erosion across landscapes, our ability to infer tectonics from topography, and the management of water resources.”

Drainages Move Slowly, Then All at Once

Water falling on a landscape flows downhill, accumulates in rivers, and eventually drains into lakes, wetlands, or oceans. Drainage divides are topographic boundaries that control the water’s path.

“If a drop of water falls on one side or the other of a drainage divide, it will follow a different route,” Attal said. He used North America’s Great Divide as an example: “If a drop falls on the west side of the divide, it goes to the Pacific; if it falls on the other side, it goes to the Atlantic.”

A drainage divide migrates when the rivers on one side of the ridge erode more rapidly than on the other. In response, rivers may change their course or even reverse direction.

Because divide migration has a significant effect on landscapes, researchers are interested in how—and how quickly—it happens. But so far, it has been difficult to determine the rate at which drainage divides migrate on short timescales.

“Geomorphic markers capable of recording past divide locations, such as alluvial terraces, are often eroded away,” explained Elhanan Harel, a geomorphologist at the Geological Survey of Israel and a coauthor of the study, which appeared in Proceedings of the National Academy of Sciences of the United States of America.

Most of the movement happened in two intervals, during which the drainage divide migrated across the landscape at twice the average rate.

Previous studies have used cosmogenic nuclide dating to measure erosion on either side of drainage divides. These erosion rates, along with other variables, were fed into an equation that estimates the rate of drainage divide migration.

This approach, however, presents several drawbacks. The equation relies on a simplified geometric model of the drainage divide, which may not accurately describe a specific site. In addition, cosmogenic nuclide dating provides erosion rates that are averaged over a river basin, which may not match erosion at the drainage divide. The erosion rates inferred from cosmogenic nuclides are also time averaged, making it impossible to track short-term changes.

Harel and his coauthors overcame these difficulties by studying unusually well-preserved river terraces in Israel’s dry southern Negev Desert. River terraces, created as rivers slowly erode and leave behind steps that represent previous levels of the valley floor, are valuable markers of regional geomorphology. At the Negev Desert site, each terrace records a past location of the drainage divide, enabling Harel and others to trace the divide’s migration step by step.

The researchers used a technique called optically stimulated luminescence to date when the terraces formed. Collating dates on the sequence of terraces, they reconstructed the drainage divide’s 258-meter migration over the past 227,000 years.

Most of the movement, they found, happened during two intervals, from 245,000 to 183,000 years ago and 36,000 to 26,000 years ago, during which the divide moved across the landscape at twice the average rate.

Wet Climates May Drive Rapid Migration

Although the southern Negev Desert has been mostly dry for at least a million years, its arid state has been punctuated by occasional wet periods: One occurred around 220,000–190,000 years ago, and another took place between 35,000 and 20,000 years ago. These periods coincide with intervals of rapid drainage migration.

Increased weathering and the timing of groundwater recharge in the southern Negev indicate that extreme storms and floods occurred at those times.

The researchers simulated the physical processes of river incision to evaluate whether climate shifts could explain the observed divide migration rates. They found that a scenario assuming constant climate conditions couldn’t reproduce their observations from the Negev, but one that included intermittent climate shifts matched the results exactly.

“Our study provides the first direct evidence linking divide migration to climate fluctuations on much shorter timescales.”

The new analysis supports the idea that climate and rainfall drive landscape changes. “While previous studies have demonstrated that tectonic forces can drive divide migration over million-year timescales, our study provides the first direct evidence linking divide migration to climate fluctuations on much shorter timescales,” Harel said.

Attal agreed that the study helps researchers understand the connection between climate and drainage patterns. “It is very interesting that [the authors] found that the divide tends to migrate in bursts during wet periods,” he said.

This knowledge may be increasingly relevant as extreme weather events—such as severe rain, storms, and floods—become more common because of climate change. In flat areas with an abundance of loose sediment, severe flooding could divert rivers and shift drainage divides, causing permanent changes to the landscape.

“I think this work highlights that some landscapes may be highly sensitive to climate change,” said Attal.

—Caroline Hasler (@carbonbasedcary), Science Writer

Citation: Hasler, C. (2025), Climate shifts drive episodic drainage changes, Eos, 106, https://doi.org/10.1029/2025EO250139. Published on 14 April 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.

Source: Geophysical Research Letters

Much of Earth’s heat uptake is passed to the ocean, making ocean heat content key for understanding long-term climate patterns. Ocean heat content is typically lower during ice ages and rises during warmer periods of glacier retreat. Over the past 1.2 million years, ice ages and interglacials have occurred in cycles lasting about 100,000 years, and we are currently in an interglacial period after the Last Glacial Maximum occurred about 20,000 years ago.

Recent climate modeling studies have suggested that ocean heat content also changes on shorter timescales of just a few thousand years as a result of intermittent changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC)—a pattern of Atlantic Ocean currents that carries warm water north and cold water south. The models suggest that a weaker AMOC leads to increased ocean heat content. However, real-world evidence to support or refute AMOC’s potential influence on ocean heat content has been limited.

Grimmer et al. present the first record of ocean heat content during the ends of the last four ice ages and the subsequent warm periods, enabling the team to test modeling predictions against paleoclimate data.

To generate the new record, the researchers analyzed the ratios of specific noble gases trapped within 59 new samples from a 3,260-meter-long ice core drilled in East Antarctica as part of the European Project for Ice Coring in Antarctica (EPICA). The noble gas ratios in different ice layers serve as fingerprints of ocean heat content at various times in Earth’s past.

Analysis of the new record showed that at the end of each of the last four ice ages, ocean heat content generally increased alongside a weaker AMOC, as predicted by the models. These transitions to warmer interglacial periods, known as deglaciations, last several thousand years. The record also showed evidence of millennial-scale changes in ocean heat content that occurred alongside changes in ocean circulation. When the AMOC strengthened, ocean heat content either increased at a slower pace or decreased.

These findings align with the prior modeling predictions, supporting the idea that on millennial timescales, the AMOC plays a key role in controlling heat uptake by Earth’s oceans. In turn, this interaction likely influences subsequent sea levels, climate conditions, and atmospheric carbon dioxide levels. (Geophysical Research Letters, https://doi.org/10.1029/2024GL114415, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), When ice ages end, ocean circulation fine-tunes ocean heat, Eos, 106, https://doi.org/10.1029/2025EO250137. Published on 14 April 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.

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

Ice sheets are formed by the slow transformation of snow into ice. Large masses of ice, such as the Antarctic ice sheet, deform under their own weight and transport the ice from the interior of the continent to the coast, eventually breaking off and forming icebergs. The flow of ice is non-Newtonian, which means that its viscosity decreases as it deforms more. Recent research has shown that this effect may be even stronger than what current computer models use.

Getraer and Morlighem [2025] evaluate what the consequences of ice being an even more nonlinear material may be on its stability and contribution to sea level rise. The authors find that the sector of Thwaites glacier in West Antarctica would lose 32% more ice by 2100, and 70% by 2300. Current estimates of the future contribution of the ice sheets to sea level may therefore be strongly underestimated.

Citation: Getraer, B., & Morlighem, M. (2025). Increasing the Glen–Nye power-law exponent accelerates ice-loss projections for the Amundsen Sea Embayment, West Antarctica. Geophysical Research Letters, 52, e2024GL112516. https://doi.org/10.1029/2024GL112516

—Minghua Zhang, Former Editor-in-Chief, Geophysical Research Letters

Text © 2024. 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.

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

The initial draft of President Donald Trump’s budget request proposes devastating cuts to NASA’s science research, future space missions, and field centers. The draft budget request, reported by Ars Technica and The Washington Post, proposes an overall 20% cut to NASA’s budget, from about $25 billion to $20 billion.

“This is an extinction-level event for NASA science,” Casey Dreier, chief of space policy for the Planetary Society, told The Washington Post. “It needlessly terminates functional, productive science missions and cancels new missions currently being built, wasting billions of taxpayer dollars in the process. This is neither efficient nor smart budgeting.”

The overwhelming majority of the cuts would come from NASA’s Science Mission Directorate (SMD), which would face a more than 50% cut from $7.5 billion to just $3.9 billion. This division includes all planetary science, Earth science, astrophysics, heliophysics, and biological and physical science research.

The draft budget request proposes a 68% cut to astrophysics (from $1.5 billion to $487 million), a more than 43% cut to heliophysics (from $805 million to $455 million), a 30% cut to planetary science (from $2.7 billion to $1.9 billion), and a 53% cut to Earth science (from $2.2 billion to $1.033 billion).

The proposal retains funding for the Hubble Space Telescope and the James Webb Space Telescope, but kills funding for the upcoming Nancy Grace Roman Space Telescope, which is fully assembled, on budget, and on schedule to launch in 2 years.

Also on the chopping block are the funding for the DAVINCI+ mission to Venus and the Mars Sample Return joint mission with the European Space Agency, which has been a budgetary flashpoint for years.

— Casey Dreier (@caseydreier.bsky.social) 2025-04-11T17:45:09.472Z

NASA’s Earth science division within SMD is home to NASA’s Earth observing satellite programs and climate research. Combined with continued attacks on NOAA and the National Weather Service, such steep budget cuts to NASA Earth science would nearly eliminate the United States’s capacity to study climate change and protect people from increasingly severe climate impacts.

The draft budget also appears to seek to force the closure of NASA’s Goddard Space Flight Center in Greenbelt, Md., which employs more than 10,000 civil servants and contractors.

 
Resources

•  Trump White House budget proposal eviscerates science funding at NASA (Ars Technica)
•  Massive cuts to NASA science proposed in early White House budget plan (Washington Post)
•  Historical NASA Budget Data (Casey Dreier, The Planetary Society)
•  Get Involved: AGU Science Policy Action Center
 

“NASA Goddard and the NASA science missions are critical to discovering the secrets of the universe and the planet we live on and have a direct bearing on our leadership in technological innovation and our national security,” wrote U.S. Senator Chris Van Hollen (D-Md.) in a statement. Van Hollen is the Ranking Member of the Appropriations Subcommittee on Commerce, Justice, Science, and Related Agencies.

“This is a wholly unserious budget proposal,” Van Hollen noted. “I will fight tooth and nail against these cuts and to protect the critical work being done at NASA Goddard.”

On 9 April, Jared Isaacman, Trump’s nominee for NASA administrator, said in his Senate hearing that he had no knowledge of any planned budget cuts to NASA and had no present intentions of cancelling existing programs. Notably, he did not commit to keeping all NASA field centers open given multiple chances to do so. Isaacman repeatedly emphasized that he was committed to ensuring U.S. dominance in the space race against China, which also seeks to put humans on the Moon and Mars, as well as expand its exploration science program throughout the solar system. These budget cuts would make that goal much harder to achieve.

With Trump’s proposed NASA budget…1st samples from Mars:

Source: Geophysical Research Letters

In magnetic reconnection, adjacent magnetic field lines break and snap together to form new lines. This process converts magnetic energy to both thermal energy, or heat, and kinetic energy, or the acceleration of particles, creating jets of electrons and ions. Magnetic reconnection plays a key role in many outer space events such as solar flares and aurorae, as well as in laboratory methods related to nuclear fusion.

Several years ago, observations of Earth’s magnetic field by NASA’s Magnetospheric Multiscale mission led to the discovery that magnetic reconnection can occur with only electron jets, without also involving the acceleration of ions. These events also have a relatively high reconnection rate, meaning the involved magnetic field lines snap together quickly. Now Fan et al. report the results of new simulations that deepen the understanding of these electron-only events.

The researchers applied a computational method known as particle-in-cell simulation to model the behavior of ions and electrons during magnetic reconnection. They ran 12 simulations to explore what factors might underlie electron-only reconnection.

The simulations revealed that the electron-only status of reconnection occurs when field lines outside of the electron diffusion region do not bend enough, leading to an underdeveloped ion diffusion region. This atypical bending happens in the early stage and may continue throughout the process if the entire system size (the size of the area in which reconnection occurs) is smaller than the radius of the path along which the ions travel.

The team also realized that magnetic reconnection and field line bending may not develop at the same pace. A relatively thin initial current sheet allows the reconnection rate to peak before field lines are fully bent, leading to calculations of high reconnection rates if they are normalized by ion parameters. However, the calculations of the reconnection rate are more typical when they are normalized by electron parameters.

These findings could help clarify the fundamental physics of magnetic reconnection, the authors suggest. (Geophysical Research Letters, https://doi.org/10.1029/2024GL113889, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), New insights into an enigmatic form of magnetic reconnection, Eos, 106, https://doi.org/10.1029/2025EO250138. Published on 11 April 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.

Cycles of ice sheet growth (glacials) and intervening warmth (interglacials) in Earth’s past—largely triggered by shifts in the amount of solar radiation (insolation) reaching the planet—have been characterized by major changes in global atmospheric carbon dioxide (CO2) levels, sea levels, and temperatures. Around the time of the Last Glacial Maximum 20,000 years ago, for example, average global temperatures were roughly 6°C (11°F) colder, and sea levels were more than 120 meters (400 feet) lower than today, whereas ice covered about a quarter of Earth’s land surface.

Such changes have had profound effects on ecosystems, particularly coastal ecosystems, including coral reefs. And as CO2 levels, temperatures, and sea levels rise rapidly around the world today, modern ecosystems—humans included—will likely continue to experience major impacts as well.

Coral reef systems are highly sensitive to sea level and climate, and fossil reefs preserve reliable records of past variations.

Yet many unknowns remain about the mechanisms that control climate transitions, particularly during past episodes of rapid warming. These unknowns raise critical questions about present and future warming as well: Are predictions of catastrophic sea level rise—up to several meters—resulting from ice sheet collapse valid? Will the behavior and effects of annual to interannual climate phenomena, such as the El Niño–Southern Oscillation and seasonal rainfall, change as the average global climate changes?

Also uncertain is how coral reefs and coasts will respond to associated environmental stresses. Coral reef systems are highly sensitive to sea level and climate, and fossil reefs preserve reliable records of past variations. Yet our understanding of these variations is severely limited because we lack continuous fossil coral records, particularly from periods of abrupt climate instability. Such records are exceptionally rare given the specific conditions required to build and preserve fossil reef sequences over extended periods and the difficulty of sampling them where they do occur.

In fall 2023, scientists and crew on the International Ocean Discovery Program’s (IODP) Expedition 389 (X389) employed an advanced, remotely operated seabed drilling system to access the interiors of submerged, or “drowned,” fossil reefs off the island of Hawai‘i for the first time (Figure 1). The reef sequences there contain globally unique records of sea level and climate change—and their impacts on reef ecosystems—over the past 500,000 years [Webster et al., 2025].

Fig. 1. A unique sequence of drowned fossil coral reefs was sampled off Hawai‘i during X389. (a) Sampling sites (red markers) are indicated along with their depths below sea level and name (H1, H2, etc.). (b) Sea level changes (blue curve) are shown through the cold glacials (blue shading) and warm interglacials (orange shading) over the past 600,000 years [Rohling et al., 2009; Elderfield et al., 2012; Lambeck et al., 2014]. New preliminary age data (red bars) confirm that reefs H1–H8 (gray bars) span 13 glacial-interglacial intervals (termed marine isotope stages (MIS), numbered boxes), including rapid climate transitions. ka = thousand years ago. Credit: Adapted from Webster et al. [2025], CC BY 4.0 Hawai‘i’s Unique Reef Records

Hawai‘i is geologically special. Located over an active volcanic hot spot, it has been—and continues to be—built up by successive eruptions. As the underlying mantle compensates for the increasing weight of the island, the ocean crust has experienced nearly constant subsidence over the past 500,000 years. This subsidence creates space that accommodates growth and vertical expansions of reefs, which, as they accumulate and fossilize, capture conditions through glacial-interglacial intervals in great detail (Figures 1b and 2). These reefs ring the island, forming a spectacular sequence of increasingly older terraces between 100 and 1,500 meters below present sea level (Figure 1a).

Rapid sea level rises linked to catastrophic ice sheet collapse and abrupt meltwater pulse events during deglaciations cause reef drowning.

The reefs have been the subject of 4 decades of data collection and study involving multiple methods of seafloor imaging (bathymetric, backscatter, and seismic) and sampling (with dredges, submersibles, and remotely operated vehicles), as well as geochronologic methods and numerical modeling [Webster et al., 2009]. These prior data underpin our knowledge of fossil reef development and motivated the scientific rationale and drilling strategy of X389.

As Hawai‘i subsides at a rate of 2.5 millimeters per year, space below the ocean surface is created for reef growth in the near term (Figure 2). But how do large and longer-term sea level changes occurring through glacial-interglacial intervals affect reefs?

Reef growth initiates during sea level highstands and continues during glaciation as sea levels slowly drop. If sea level falls quickly, outpacing the island’s subsidence rate, the living part of the reef dies as it is exposed above the waves. If, on the other hand, sea level rises too quickly and new reef growth—which requires the sunlight available near the ocean surface—fails to keep up, the reef will deepen and ultimately drown.

Fig. 2. This conceptual model illustrates the development and accumulation of drowned fossil coral reefs and other rock facies (e.g., microbialites, volcanic deposits) in different paleoenvironments around Hawai‘i over the past 100,000 years in response to rapid island subsidence, which creates accommodation space (double-headed arrow), and changing sea levels (dark blue curve). ka = thousand years ago; mbsl = meters below sea level. Credit: Adapted from Webster et al. [2025], CC BY 4.0

Rapid sea level rises linked to catastrophic ice sheet collapse and abrupt meltwater pulse events during deglaciations thus cause reef drowning [Sanborn et al., 2017]. Then, during the subsequent warm high sea level stand, a new reef is initiated upslope, and the cycle starts again.

Numerical models of reef growth and demise, forced by changes in sea level, predict that the Hawaiian terraces comprise thicker sequences of fossilized reef—100–150 meters per glacial cycle—compared with those built on stable margins such as the Great Barrier Reef. As such, the Hawaiian expanded sequences hold great promise for providing sea level and climate records of unprecedented resolution and detail.

To sample these Hawaiian reefs across a range of water depths and challenging lithologies (they commonly fragment and break), researchers required a novel drilling system—unavailable to the scientific community until recently—that could penetrate the reef interior rather than just scratch its surface.

The Core of the Matter

The X389 team found the needed technology in Benthic’s fifth-generation portable remotely operated drill (PROD5). This commercial, tethered device can be guided to and secured at seafloor targets as deep as several kilometers, where its automated capabilities allow it to collect long sample cores (up to 73 meters below the seafloor in the case of X389). A major advantage of seafloor drills over ship-based systems is that they’re stationary, which makes it easier to keep constant weight on the drill bit and improves recovery of continuous core segments.

Scenes from X389’s drilling operations show the PROD5 drill (a) being deployed over the side of the MMA Valour and (b) landing on the seafloor, as well as (c) team members processing and archiving a core collected from a well-preserved fossilized massive Porites coral. Credit: Jody Webster

Sailing aboard the MMA Valour, the expedition used PROD5 to obtain reef material from roughly the past 500,000 years to address four major objectives: (1) measuring the extents of past sea level variations, (2) investigating seasonal to millennial climate and oceanic change, (3) assessing coral reef ecosystem responses to abrupt sea level and climate changes, and (4) improving knowledge of the growth and subsidence of Hawai‘i over time.

Over the course of 2 months in fall 2023, we deployed the drill at 16 drowned reef sites offshore Hawai‘i, coring 35 holes at water depths ranging from 132 to 1,242 meters (Figure 1a). A total of 425 meters of core were recovered, comprising both reef (83%) and volcanic (17%) materials. Core recoveries averaged 66%, and numerous intervals of well-preserved reef samples exhibited recoveries greater than 90%, significant achievements compared with recoveries from prior expeditions. For example, core recoveries averaged 27% using a ship-based drilling system during Expedition 325 to the Great Barrier Reef in 2010 [Webster et al., 2011].

The deployments were largely successful, but the expedition was not all smooth sailing.

The deployments were largely successful, but the expedition was not all smooth sailing. Technical issues with the drill, including mechanical breakdowns and difficulties penetrating heterogeneous coral reef material, limited our ability to reach all target depths.

Moreover, the expedition did not adequately engage with community members about the plans and purpose of its research or about concerns it may have posed. This regrettable oversight alienated members of the local and Native Hawaiian communities, some of whom expressed frustration at not being informed or consulted prior to the Valour’s arrival offshore and voiced uncertainties over possible environmental harms.

In addition to damaging the expedition’s relationship with local communities, the lack of timely and vital engagement directly affected the science we could pursue. The concerns raised by community members contributed to the denial of a permit to drill in state waters—a decision received after X389 was already at sea—meaning that we could not sample at some young, science-critical reef sites as originally planned.

Consequently, we pivoted our approach to add more sites in federal waters where we could sample other young reef sequences and to drill transects of shorter, but high-quality, cores to capture small sea level oscillations. Since the research cruise, expedition members have sought to redouble community engagement efforts to redress the offenses and concerns caused by the expedition.

Ancient Anatomy Lessons Fig. 3. Line scan images of two core sections show shallow, in situ reef frameworks characterized by branching Porites coral with well-developed encrusting coralline algae, vermetid gastropods, and microbialite deposits. These cores were collected from the same H2 reef terrace but on opposite sides of Hawai‘i, (a) one near Kawaihae on the leeward, dry side and (b) one near Hilo on the windward, wet side; they are indicative of rapid reef accretion in response to sea level rise and differing riverine inputs. Credit: Adapted from Webster et al. [2025], CC BY 4.0

Analysis of the hundreds of meters of core collected during X389 will reveal, for the first time, the complex internal anatomy and composition of Hawai‘i’s extensive reef packages through the past half million years. Preliminary visual observations have already offered glimpses of exquisite new details, including drowning reef sequences formed during the terminations of glacial periods [Webster et al., 2025]. The building blocks of these drowning reefs include branching, columnar, and massive shallow corals; several types of microbialite; thick crustose coralline algae (Figure 3); lithified and unlithified sediments; and a diversity of volcanic flows and associated sediments.

Observations so far also suggest that our sampling captured distinct shallow, intermediate, and deep reef communities and depositional settings, as well as the first evidence of major lithologic boundaries indicating repeated reef initiation and demise, as predicted by models and previous seafloor observations [Webster et al., 2009] (Figure 2). Furthermore, substantial differences in sedimentary contributions to the reefs between the dry and wet sides of Hawai‘i highlight that variations in precipitation, sediments, and nutrient input might influence reef evolution (Figure 3).

Fig. 4. A suite of nondestructive analytical techniques from across the electromagnetic spectrum was used to investigate fossil coral reef cores collected during X389. Shown here are representative high-resolution images of a robust branching Porites coral and other components from the same core from the H2 reef terrace (dated to between MIS7 and MIS6). The images include (a) a line scan image, (b) an X-ray computed tomography image showing 3D density changes, and hyperspectral images providing mineralogic information such as the (c) aragonite index, (d) calcite index, and (e) minimum wavelength mapping. Credit: Adapted from Webster et al. [2025], CC BY 4.0

Early analyses of the cores have been done using a suite of nondestructive imaging techniques (Figure 4). X-ray computed tomography is providing 3D reconstructions of massive Porites coral specimens, which often provide accurate records of past ocean conditions. In addition, traditional high-resolution line scans integrated with high-resolution hyperspectral scanning of the cores are revealing carbonate and other minerals (e.g., aragonite, calcite, clay, and iron), helping to guide sampling and more detailed analyses of the cores.

Windows into the Past and Future

The material recovered during X389 is between 10,000 and 500,000 years old and includes hundreds of well-preserved samples. These samples will be used to reconstruct the first absolute dating of sea level changes during portions of this time window. Putting absolute dates to these changes will have profound implications for testing theories about the drivers and triggers of past glacial-interglacial cycles and for validating climate and ice sheet models that are critically important for predicting sea level changes resulting from current and future global warming.

Further, the X389 cores include more than 300 Porites coral specimens with annual banding that will provide the first estimates of seasonal to millennial paleoclimate variability in the region. Geochemical analyses can be used to estimate monthly oceanographic variability with respect to temperature, precipitation, nutrient dynamics, carbon chemistry, and pH.

Assessing the nature of variability at different temporal scales will help answer critical questions. For example, were the occurrence and seasonality of extreme climate events in the past dependent on the background average climate state at times when global temperature, Pacific storm tracks positions, solar insolation, and atmospheric CO2 levels were different? The state dependency of high-frequency temperature and hydroclimate variability is a key question today as Earth warms.

The sequences of reef lithologies recovered during X389, including volcanic flows and the diverse variety and shapes of reef-building organisms, will be interpreted to reveal a story of ecosystem response to geological processes and paleoclimatic variations in sea level and oceanographic conditions. This interpretation will inform broader understanding of the factors that control reef growth, reef health, and coastal resilience in subsiding island settings in the face of future changes in hydroclimate, ocean temperature, nutrient availability, sediment supply, and ocean pH.

The X389 science party is working together to continue studying the collected cores in greater detail to address the project’s scientific goals. And we welcome contributions from external scientists as well: Careful sampling of the cores has left much of the material intact, and as of late February 2025, anyone can request X389 samples from the IODP core repository at Texas A&M University. With concerted and collaborative efforts, we can continue the flexible and inclusive approach of IODP—even as the Sun sets over its current phase—to advance knowledge of the paleoclimate over the past 500,000 years and understanding of what conditions Earth may experience in the future.

Acknowledgments

We thank the entire IODP 389 Expedition Science Party, ECORD Science Operator (ESO) support staff, Benthic drilling team, MMA surveyors, and the captain and crew of the MMA Valour for their outstanding work on the offshore and onshore phases of the expedition. IODP Expedition 389 was supported by funding from the various national funding agencies of the participating IODP countries.

References

Elderfield, H., et al. (2012), Evolution of ocean temperature and ice volume through the mid-Pleistocene climate transition, Science, 337(6095), 704–709, https://doi.org/10.1126/science.1221294.

Lambeck, K., et al. (2014), Sea level and global ice volumes from the Last Glacial Maximum to the Holocene, Proc. Natl. Acad. Sci U. S. A., 111(43) 15,296–15,303, https://doi.org/10.1073/pnas.1411762111.

Rohling, E. J., et al. (2009), Antarctic temperature and global sea level closely coupled over the past five glacial cycles, Nat. Geosci., 2(7), 500–504, https://doi.org/10.1038/ngeo557.

Sanborn, K. L., et al. (2017), New evidence of Hawaiian coral reef drowning in response to meltwater pulse-1A, Quat. Sci. Rev., 175, 60–72, https://doi.org/10.1016/j.quascirev.2017.08.022.

Webster, J. M., et al. (2009), Coral reef evolution on rapidly subsiding margins, Global Planet. Change, 66(1–2), 129–148, https://doi.org/10.1016/j.gloplacha.2008.07.010.

Webster, J. M., et al. (2011), Great Barrier Reef environmental changes, Proc. Integrated Ocean Drill. Program, 325, https://doi.org/10.2204/iodp.proc.325.2011.

Webster, J. M., et al. (2025), Hawaiian drowned reefs, Proc. Int. Ocean Discovery Program, 389, https://doi.org/10.14379/iodp.proc.389.2025.

Author Information

Jody M. Webster (jody.webster@sydney.edu.au), School of Geosciences, Geocoastal Research Group, University of Sydney, Australia; and Christina Ravelo (acr@ucsc.edu), Ocean Sciences Department, Institute of Marine Sciences, University of California, Santa Cruz

Citation: Webster, J. M., and C. Ravelo (2025), Unlocking climate secrets of Hawai‘i’s drowned reefs, Eos, 106, https://doi.org/10.1029/2025EO250135. Published on 11 April 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.

Past lunar missions have detected evidence of large ice deposits in permanently shadowed regions near the Moon’s south pole. Such ice could provide astronauts with drinking water, oxygen, and rocket propellants, reducing the cost of lunar operations.

But new research has found that astronauts might not have to dig very deep or journey especially close to the Moon’s poles to find water ice. A recent study published in Communications Earth and Environment says the critical resource for future lunar explorers might lurk tantalizingly close to the surface on pole-facing slopes at lower latitudes. The Sun shines at a low angle on such regions, which may allow ice to accumulate just centimeters below the surface, where it would be insulated by lunar regolith.

The Moon’s low axial tilt means that craters and low-lying areas near the south pole never see direct sunlight. This lack of sunlight would allow even surface ice deposits to remain frozen for a long time—perhaps billions of years. Because of the likely presence of ice, both NASA and China’s space agency have announced plans to land astronauts near the south pole and eventually establish permanent outposts there.

The Chandrayaan-2 orbiter photographed the Vikram lander from orbit. Credit: Indian Space Research Organisation

Locations farther from the poles “can also become potential locations for future human habitats, with better illumination and smoother topography than the poles. These regions pose less technical challenges for landing and operations.”

“Our study reveals that the poles are not the only options for future exploration,” said K. Durga Prasad, lead author of the report and a planetary scientist at the Physical Research Laboratory in Ahmedabad, India. Locations farther from the poles “can also become potential locations for future human habitats, with better illumination and smoother topography than the poles. These regions pose less technical challenges for landing and operations.”

“This result is very much consistent with both theoretical modeling studies and observations made by Lunar Reconnaissance Orbiter,” said Timothy McClanahan, an emeritus planetary scientist at NASA’s Goddard Space Flight Center who was not involved with the study.

First Measurements Since Apollo

The new lunar temperature data come from Chandra’s Surface Thermophysical Experiment (ChaSTE), an instrument aboard the Vikram lander, which itself was part of India’s Chandrayaan-3 mission. Vikram touched down on 23 August 2023 at 69° south latitude, the most southerly landing site at that time. (Two subsequent landers, both built by the American company Intuitive Machines, landed farther south, but both tipped over on landing and were unable to achieve all of their science goals.)

ChaSTE collected data continuously from 24 August to 2 September, shortly before the Sun set on the solar-powered lander (a lunar day lasts about 29.5 Earth days). The probe penetrated 10 centimeters into the regolith, with temperature sensors spaced at 1-centimeter intervals. The instrument also heated the regolith to measure its thermal conductivity.

ChaSTE provided the first direct subsurface lunar temperature measurements since the Apollo 15 and 17 missions of the early 1970s. The Apollo heat probes drilled deeper than ChaSTE did but provided fewer measurements of the top 10 centimeters. The Apollo sites also were close to the equator, where temperatures are likely to remain too warm for water ice even well below the surface, Prasad said.

An enlarged version of the Pragyan image of Vikram indicates the location of the ChaSTE instrument, which measured thermal conductivity and temperatures, and the Instrument for Lunar Seismic Activity (ILSA). Credit: Indian Space Research Organisation

Vikram landed on the rim of a shallow crater in a Sun-facing area with a 6° slope. ChaSTE and other instruments aboard the lander recorded a peak daytime surface temperature of 355 K (81.85°C). That was higher than expected on the basis of both models and observations by Diviner, an infrared instrument aboard the Lunar Reconnaissance Orbiter that has compiled temperature maps of much of the lunar surface. (Temperatures at the probe’s maximum depth ranged from 55 K to 85 K colder than surface temperatures, depending on the time of day.)

However, the temperature on a flat area just 1 meter from the ChaSTE site peaked at only 332 K (58.85°C), suggesting that a location’s slope could play a significant role in its subsurface temperatures.

The findings “validated the idea that topographic variation, even toward meter scales, has an important impact on locations where we might expect water ice to occur,” McClanahan said.

Taking the Right Angle

Modeling showed that at high latitudes, poleward-angled slopes of 14° or greater could remain cold enough to preserve ice at depths of just a few centimeters. The Sun would hit such tilted regions at a low angle, minimizing heating, and the fine-grained top layer of the regolith would be an efficient thermal blanket, effectively insulating the shallow subsurface.

“Depending on the slope, you can have a lot of temperature variation even in craters as small as a meter. One side might be quite warm, but…you could have conditions that are suitable for water ice on the poleward-facing slope.”

“Depending on the slope, you can have a lot of temperature variation even in craters as small as a meter,” McClanahan said. “One side might be quite warm, but given the low thermal conductivity of the regolith, you could have conditions that are suitable for water ice on the poleward-facing slope.” The slope angle suitable for hosting ice increases as you move farther from the pole, he added.

The Vikram team is continuing to analyze the ChaSTE observations to learn more about the thermal characteristics of the landing site and of high lunar latitudes in general, Prasad said. In addition, because temperatures are important for any lunar lander, “future missions will definitely carry similar instruments that will also help substantiate our results,” he said.

—Damond Benningfield, Science Writer

Citation: Benningfield, D. (2025), Lunar ice might be easier to reach than we thought, Eos, 106, https://doi.org/10.1029/2025EO250136. Published on 11 April 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.

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

Magma transport involves interactions of rocks and volatiles in their solid, fluid, and gas phases that must be captured by physical models across a vast range of scales. What complicates matters further is that eruptions respond to heterogeneous and time-variable source conditions modulated by a crust that experiences hysteresis due to its volcano-tectonic history. Any efforts of interpreting signals such as the multi-decadal unrest at the Campi Flegrei, Italy volcanic fields thus must find the balance between honoring the regional specifics and fundamental volcano dynamics.

Numerical scenario computation illustrating how dike populations may respond to the large-scale caldera stress field. Credit: Buono et al. [2025], Figure 7l

Buono et al. [2025] present a sweeping review that seeks to integrate rock physics, seismic tomography, and mechanical modeling into a systems-level understanding of the Campi Flegrei setting. It appears that the combination of caldera geometry and lithology leads to a crustal stress state that affects volcanic dike ascent which in turn may feed back into crustal deformation behavior. This suggests the importance of a resulting weak crustal layer for subsequent magma and gas pathways and perhaps an evolutionary scenario for similar volcanic centers. While the modeling is suggestive, there are a range of interactions and features left to be explored. However, the range of geophysical and geological constraints that are accessible in well instrumented volcanic systems points toward the potential of future, fully integrated models that might be capable of assimilating time dependent observations for improved, physics-based forecasting of volcanic hazards.

Citation: Buono, G., Maccaferri, F., Pappalardo, L., Tramelli, A., Caliro, S., Chiodini, G., et al. (2025). Weak crust owing past magmatic intrusions beneath Campi Flegrei identified: The engine for bradyseismic movements? AGU Advances, 6, e2024AV001611. https://doi.org/10.1029/2024AV001611

—Thorsten Becker, Editor, AGU Advances

Text © 2024. The authors. CC BY-NC-ND 3.0
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The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

Rail Advent has a very nice article that describes the now completed repair of the Browney Curve landslide on the East Coast Mainline railway line in England. This is a site that is dear to my heart as, for 14 years, I drove across the landslide on my way to work.

There is a Google Earth image from 2020, taken from a low sun angle, that beautifully illustrates the issues at this site:-

Google Earth image from 2020 showing the Browney Curve landslide site. Note the East Coast mainline railway running across the landslide.

The East Coast Mainline is one the most important long distance line the country. Built two centuries ago, the line links London and Edinburgh, via York and Newcastle. The Browney Curve landslide has caused issues for many years. The image below, from Network Rail, shows the scale of the problems:-

The Browney Curve landslide site. Image from Network Rail.

The hummocky terrain seen in the image is characteristic of land that is undergoing movement. The underlying surface geology consists primarily of glacial till, which causes stability issues in many locations in the UK. The embankment supporting the railway line runs below the very clear back scarp of a natural landslide, and there are clear signs of ground deformation on the slopes above and below the track.

The landslide has regularly caused damage to the track and the road, and there were concerns that a major movement could close the line for a protracted period. Prior to the works, the line was being intensely monitored at this location to ensure that the alignment was safe.

Network Rail has a good page detailing the remediation works, which primarily consist of the installation of 529 piles extending up to 25 metres into the ground to anchor the slope, plus extensive drainage works to lower pore water pressures. The gradient of the embankment has also been reduced, and there will be a tree planting programme as well.

Pell Frischmann has a good web page detailing the ground investigation and design works at the site. There is also a very good, very detailed review of the problems and the repairs on Youtube, presented by Pell Frischmann and Network Rail. This is a fantastic resource:-

The works have cost £33 million (US$43 million), representing a significant investment in the safety and resilience of the East Coast Mainline.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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A warm cup of tea could offer some unexpected health benefits.

While steeping, tea leaves soak up lead ions from water, researchers reported in ACS Food Science and Technology. Though the process doesn’t completely purify the water and is not intended for large-scale water remediation, the passive benefit could help explain the correlation between regular tea consumption and lower incidences of heart disease and stroke.

“This idea that the tea bag, or tea within the bag, would absorb something was something nobody thought about.”

Tea is known to release various compounds such as tannins and caffeine into water. But “this idea that the tea bag, or tea within the bag, would absorb something was something nobody thought about,” said Vinayak Dravid, a coauthor of the study and a materials scientist at Northwestern University.

In the lab, Dravid and his research group regularly develop spongelike materials that absorb pollutants. The composition of one of these sponges reminded study coauthor Benjamin Shindel of tea bags, Dravid said. Shindel, at the time a Ph.D. candidate and now a materials scientist contracting with the U.S. Department of Energy, suspected that conditions inside a cup of tea would encourage metals to stick to the tea leaves.

To test the hypothesis, Shindel and his colleagues prepared solutions made of water with different concentrations of lead, ranging from 10 parts per billion—EPA’s trigger level for lead—to highly toxic levels of 10 parts per million. Then they heated the solutions to 85°C (185°F, just below the boiling point of water) and prepared different kinds of teas, including traditional black, green, oolong, and white teas brewed from the Camellia sinensis plant as well as the herbal teas rooibos and chamomile. After steeping the tea leaves for a range of times—anywhere from a few seconds to 4 hours—the researchers measured how much lead was left in each cup.

Spilling the Tea

Black and green teas were the most effective at removing lead, the team found, although the type of tea had less efficacy than the time it steeped. Finely grinding the leaves before steeping slightly improved their performance, likely because the increased surface area left more space for lead atoms to attach to the leaves. Steeping leaves in a cup of black tea for 5 minutes removed about 15% of the lead from the laboratory solutions. White and herbal teas, whose leaves remain smooth as they steep, were less effective.

The wrinkled surface of black tea leaves, seen here under a scanning electron microscope, may contribute to an increased surface area onto which lead and other metal ions adsorb. Credit: Vinayak P. Dravid Group/Northwestern University

The longer the leaves steeped, researchers found, the more lead adsorbed onto them. The longer leaves steep, however, the more bitter the tea becomes.

Tea’s metal-remediating benefits weren’t limited to lead. The team also prepared separate solutions of cadmium, chromium, copper, and zinc. Ions of each adsorbed onto the leaves.

In addition to the leaves themselves, the team also experimented with whether the type of tea bag influenced the amount of metal removed. Though nylon and cotton tea bags didn’t remove any lead, the metal did bind to cellulose (or “wood pulp”) tea bags.

Previous research has shown that C. sinensis can absorb metals from soil and store them in its leaves, so “there is always a risk, and obviously a concern, that you are actually then contributing those heavy elements and heavy toxins into water again when you make tea,” Dravid said.

But the new study suggests that metals will stick with the plant and not be released into the surrounding environment. “What our work showed,” Dravid explained, is that C. sinensis “has an affinity for heavy metals—that even if they exist in the leaf, they actually will remain. And that’s so reassuring.”

Brewing with Perspective

Tea leaves are not a substitute for existing methods of water purification, the authors emphasized. Most of the lead that enters drinking water does so through lead pipes connecting water mains and homes, and many domestic faucets or under-sink filters can remove more than 90% of lead ions.

Instead, tea leaves are “a way of reducing the lead exposure that occurs naturally,” explained Marc Edwards, an environmental engineer at Virginia Tech who was not involved in the study. Tea leaves could help mitigate—though not completely remove—the presence of other metals that enter drinking water either through corrosion (e.g., of copper or zinc pipes) or through erosion of mineral deposits like chromium.

“It’s not going to remove all the metal in the water.…But it is removing a fraction that may be meaningful from a public health perspective.”

“It’s not going to remove all the metal in the water, 99.9% or something like this,” Shindel agreed. “But it is removing a fraction that may be meaningful from a public health perspective.” If brewing tea removes 15% of lead and a person drinks enough tea to account for one fifth of their daily liquid consumption, that consumption could lower their lead intake by 3% compared with someone who drinks no tea.

This passive removal may help explain the observed relationship between tea consumption and a lower incidence of certain health issues such as heart disease, high blood pressure, and stroke, the researchers suggest. All three conditions have been associated with lead intake. But more research is needed to determine whether a direct link exists between tea consumption and metal intake, they said.

Though tea leaves can’t eliminate lead in water completely, their widespread use may help reduce an individual’s lead exposure over time.

Still, there’s no need to oversteep your morning cup, Shindel said. “I don’t think people should be changing their tea consumption patterns, or brewing really bitter tea…so they can get more metals out.”

—Skyler Ware (@skylerdware), Science Writer

Citation: Ware, S. (2025), Tea leaves remove lead from water, Eos, 106, https://doi.org/10.1029/2025EO250134. Published on 10 April 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.

After decades of nondetections and tantalizing maybes, astronomers have definitively detected an aurora on Neptune. Using the James Webb Space Telescope (JWST), researchers detected an infrared auroral glow and the spectral signature of a key tracer of aurorae in Neptune’s upper atmosphere for the first time. The spectrum of this ionized molecule also suggests that Neptune’s upper atmosphere has cooled significantly since Voyager 2’s flyby 34 years ago.

Aurorae have been seen on planets and moons throughout the solar system. Theories predicted that Neptune should have aurorae, too, but previous attempts to detect them failed, said Henrik Melin, a planetary aurora researcher at Northumbria University in Newcastle upon Tyne, United Kingdom (U.K.).

“I’ve spent many, many nights up a mountain trying to detect this stuff using ground-based telescopes. You spend four nights staring at Neptune, and you see nothing,” Melin said.

This auroral detection is “completing the set” of giant planet aurorae, he added. “We have Jupiter, we have Saturn, we have Uranus. We now have Neptune.”

Chilly Aurora

Aurorae occur when charged particles from the solar wind or a nearby volcanic moon, for example, interact with a body’s magnetosphere and upper atmosphere. Some aurorae glow in visible light, like on Earth and some of Jupiter’s moons. Mercury’s aurorae shine in X-ray light.

On planets with hydrogen-dominated atmospheres like Jupiter, Saturn, and Uranus, aurorae typically glow in the infrared or ultraviolet and are traced by the presence of the trihydrogen cation (H3+). Anywhere they occur, aurorae can help scientists understand the inner workings of a planet’s magnetosphere.

“Auroral emissions provide important insight into the space environment of a planet.”

“Auroral emissions provide important insight into the space environment of a planet, and this is particularly important for Neptune, which has a very bizarre magnetic field,” said Jonathan Nichols, a planetary aurora researcher at the University of Leicester in the U.K. who was not involved with the new discovery.

Voyager 2’s brief 1989 flyby suggested that Neptune’s magnetic field is both tilted from its axis of rotation and offset from the center of the planet. The flyby also detected some hints of a possible aurora that astronomers have been hoping to confirm ever since. Models of Neptune’s atmosphere and magnetic field have suggested that Neptune’s aurorae should also be traceable by H3+ and have even predicted the longitudes at which they should appear. But detecting the aurorae proved elusive.

In June 2023, Melin and his colleagues obtained near-infrared JWST spectra of Neptune, originally intending to explore the circulation of Neptune’s middle atmosphere. The observations unexpectedly revealed an infrared auroral glow as well as a shockingly clear infrared spectrum of H3+ emitted by the planet’s upper atmosphere.

The intensity of the H3+ spectrum suggests that the upper atmosphere generating the aurora is 85°C (358 K), a significant cooldown from the 477°C (750 K) temperature measured by Voyager 2.

“It’s great to see this addition to the family portrait of solar system auroras.”

“That was quite a surprise,” Melin said.

Neptune’s seasons are roughly 41 Earth years long, so this dramatic cooling took place faster than the seasonal timescale. The researchers don’t yet understand what might be driving the cooldown, Melin said, though it is likely unrelated to the unseasonably cool summer observed elsewhere in Neptune’s atmosphere.

“The consequence of these really cold temperatures means that the auroral emissions are extremely faint,” Melin said. That explains why Neptune’s aurorae eluded the gazes of ground- and space-based telescopes before. “It was just really, really cold.”

“It’s great to see this addition to the family portrait of solar system auroras,” Nichols said. “Now we know how bright the infrared emission is, we can work out the intensity in other wavelengths such as ultraviolet, and we can run models to see what the upper atmosphere is like.”

The researchers published this discovery in Nature Astronomy.

A Neptunian Day

These JWST data were clear enough to trace aurorae to specific latitudes and longitudes, “producing the first map of the aurora at Neptune,” Melin said.

What’s more, the aurorae appeared at the exact longitudes in the southern hemisphere predicted by long-standing theories.

“This is the tantalizing starting point of really getting to understand Neptune.”

“This was not a given,” Nichols explained, “since the length of the planet’s day was determined more than 3 decades ago, and the uncertainty was such that we were supposed to have lost track of what the time is at any point on Neptune.” (Uncertainty in planetary day lengths is pretty common.)

“But it appears as if it is more accurate than we thought!” Nichols added.

Later this year, the team will point JWST at Neptune several times over the course of a month to learn more about what drives its aurorae and how the planet’s magnetosphere responds to different levels of solar activity.

“By studying the morphology of the aurorae and its changes over time, we can figure out what drives it,” Melin said. The team needs more data to do that, “but this is the tantalizing starting point of really getting to understand Neptune.”

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

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Citation: Cartier, K. M. S. (2025), After 30-year search, scientists finally find an aurora on Neptune, Eos, 106, https://doi.org/10.1029/2025EO250130. Published on 10 April 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.

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

The longer a magma chamber resides in the upper crust, the more likely it will evolve to silica-rich compositions. Volcanism has been active on Mars throughout its history, but there is an apparent lack of widespread evolved magmatism, and the development of magma storage systems has been poorly constrained.

To better understand how crustal depth and temperature profile affect the evolution and growth of magma chambers on Mars, Chatterjee et al. [2025] utilize numerical modeling and compare with recent results from the InSight lander mission. Their models suggest that Mars’ crust is divided into three zones that are consistent with InSight seismic data: (1) the upper crust where small intrusions, such as dikes, dominate the upper crust; (2) the lower crust where larger magma chambers can develop and grow; and (3) a middle zone where magma chambers can occasionally grow and produce dikes that erupt at the surface.

The depths where the three magma storage zones are located depend on the crust’s temperature gradient and this study is the first to model the longevity of magma chambers on Mars as it has gradually cooled over geological time. A higher temperature gradient during Mars’ early history (the Noachian and Hesperian time periods) would have allowed larger, more long-lived upper crustal chambers to develop with the potential to feed eruptions at the surface. Seismic activity in Cerberus Fossae detected by InSight is consistent with magmatism and suggests its continued influence on the structure and make-up of the crust of Mars.

Citation: Chatterjee, A. P., Huber, C., Head, J. W., III, & Bachmann, O. (2025). Magma chamber longevity on Mars and its controls on crustal structure and composition. Journal of Geophysical Research: Planets, 130, e2024JE008798. https://doi.org/10.1029/2024JE008798

—Mariek E. Schmidt, Associate Editor, JGR: Planets

Text © 2024. 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.