EOS

Butterflies are often considered bellwether species for climate change, and to retain the cooler climates they need for their life cycles, species around the world have been shifting their habitats and migratory patterns to higher latitudes and higher elevations.

But are the plants that butterflies depend on shifting their habitats in step?

New research has found that out of 24 Southeast Asian butterflies examined, 17 of them (71%) could experience a net loss in the habitat area they share with their host plants under a high-emissions climate change scenario. Some butterfly species may lose nearly 40% of shared habitat as they retreat to cooler climes.

Losing Ground

Like most species on Earth, butterflies have a preferred temperature range. As climate change warms the planet, many butterfly species have shifted their habitats, typically moving to cooler, higher elevations or higher latitudes. But wherever they go, butterflies still need plants that provide food and host their larvae (caterpillars). Some butterflies depend on a single host species, while others can rely on several.

Plants, too, have environmental needs, but whether the insects and the plants they need are shifting their habitats at the same speeds and in the same direction has been unclear.

To compare shifting species ranges, researchers simulated how tropical Asian butterflies and their host plants would each experience habitat migration in response to a high-emissions climate change scenario (SSP585). They selected 24 butterfly species whose ranges span from dense lowland rainforests to mountainous highlands. Some species have large ranges, and others have small ranges. Some depend on a single host plant, and others can use several.

“We wanted to choose the most representative butterfly species in tropical Asia,” said Jin Chen, lead researcher on the project and a doctoral student at the University of Helsinki. “We only used climate data as the predictive factors. We wanted to see, in the worst situation, what happens to them.”

“I don’t think there’s any situation [in which] a butterfly will prefer to go a warmer place.”

They found that 17 of the 24 butterfly species would experience a net decoupling from their host plants, with shared habitat area decreasing between 6% and 39%. As expected, the decoupling in lowland areas was primarily driven by butterflies fleeing to cooler, higher-elevation areas.

“I don’t think there’s any situation [in which] a butterfly will prefer to go a warmer place,” Chen said.

But the model also predicted significant habitat decoupling in those cooler, higher-elevation regions, which was unexpected. The loss of shared highland habitat was primarily driven by the host plants not being able to thrive there, and as a result, the butterflies had no support system when they arrived. Butterfly species that are pickier about their plants experienced the biggest coupled habitat losses.

“The hot spots of this decoupling are mostly in the mountain regions of tropical Asia, including Borneo and the boundary of Laos, Vietnam, and Cambodia,” Chen said, as well as “the north of Myanmar close to the Himalayas.”

The model did predict that seven butterfly species would gain shared habitat with plants, with net gains of 1%–42%. Those gains were a result of several host plants expanding their ranges significantly in a warmer climate. The butterflies that relied on those plants had more options despite their own habitat shifts.

The team presented their results on 15 December at AGU’s Annual Meeting 2025 in New Orleans.

“There’s a lot of uncertainty in how butterflies are responding or will respond to climate change globally—and this is especially true in the tropics where data are generally sparse and species interactions complex,” said Timothy Bonebrake, a conservation scientist at the University of Hong Kong who was not involved with this research. “But yes, there is evidence that Asian species are shifting their distributions in response to warming and other environmental changes.”

“What role host plants play in such movements is less clear and needs further investigation,” he added. “So studies like this that model host and butterfly responses are a useful first step for understanding such impacts.”

Fluttering Away

“Modeling species interactions under global change can provide important perspectives for managers and conservation planners by emphasizing key linkages in the ecosystem,” Bonebrake said. “Indeed, for many butterfly species, host plant availability will be a key limiting factor that constrains distribution tracking. Research like this can help to identify which types of species might need attention or active intervention under rapid warming.”

Chen noted that because the team’s model used only climate change as a predictive factor, it might not have fully captured how plant ranges will change. Although temperature shifts, driven by climate change, are the most important factor for butterflies, plants also respond to land use changes, she said. Future modeling will include predicted land use change under different emissions scenarios and thus will provide more precise predictions about which butterfly species could thrive or falter.

“Hopefully, this ability will also give species an additional avenue for persisting in rapidly changing environments.”

Still, these initial models provide clues about which species are under more threat than others and can spark ideas about how humans can intervene to protect vulnerable pollinators. People living in cooler areas to which butterflies are fleeing can help support the insects by protecting their host plants from destructive land use and by planting more pollinator-friendly plants to support butterflies’ life cycles.

“We sometimes underestimate the ability of butterflies to switch host plants or otherwise alter their life histories to cope with climate change,” Bonebrake said. “When they do shift hosts, it introduces an additional element of complexity with respect to climate change projections. But hopefully, this ability will also give species an additional avenue for persisting in rapidly changing environments.”

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

Correction 19 December 2025: The photo caption has been corrected to identify the butterfly as Idea leuconoe, not Idea stolli.

Citation: Cartier, K. M. S. (2025), Climate change could drive butterflies and plants apart, Eos, 106, https://doi.org/10.1029/2025EO250481. Published on 19 December 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 low-latitude highlands region of southwestern China experienced two major climate events in recent years: a severe drought in 2009–2010 and an extreme heat wave in 2019. Though both sprang from similar large-scale atmospheric circulation patterns, the events produced different responses, raising questions about how multiple stressors can push ecosystems toward contrasting outcomes.

Southwestern China’s highlands system offered scientists a chance to study the ways a sensitive ecosystem reacted to both a once-in-a-century drought and an exceptional heat wave. Pan et al. analyzed soil moisture, vegetation productivity, and temperature using remote sensing data and nonlinear structural equation modeling. They discovered a distinct “personality switch” in the way the ecosystem responded to the second event versus the first.

In 2010, when drought left the soil very dry, the ecosystem’s productivity was limited by the amount of available water. During that drought, plant growth slowed as vegetation operated in survival mode and restricted water to its roots. In 2019, when the soil was moistened by previous rains, water was not a limiting factor. Instead, the hot temperatures served as an energy source and caused plant growth to thrive.

Wetter antecedent conditions helped the ecosystem better weather the heat, the research showed. This concept of “hydrological memory” helps explain why the ecosystem reacted so differently to two extreme events. Such a nonlinear effect can be hard to capture in traditional modeling, so these findings have important implications for future modeling and climate change projections, the authors say. Untangling seemingly unpredictable ecosystem behaviors, they continue, could help improve understanding of our planet and its future. (AGU Advances, https://doi.org/10.1029/2025AV001973, 2025)

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

Citation: Owen, R. (2025), An ecosystem never forgets, Eos, 106, https://doi.org/10.1029/2025EO250472. Published on 19 December 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: Journal of Advances in Modeling Earth Systems (JAMES)

An existing body of research indicates that climate change is making tropical cyclones wetter and more powerful.

Now, new research is indicating the same thing may be happening to the precursors of these storms: the wet weather systems that sometimes give rise to destructive hurricanes and often cause hazardous rain and flooding.

Tropical cyclones don’t spring into existence fully formed. Around 85% of Atlantic hurricanes, for instance, originate from African easterly waves, westward-moving disturbances of low pressure over Africa in which warm, humid air rises into the atmosphere from below and forms rain clouds. Despite these weather systems’ critical role as “seeds” for tropical cyclones, however, it’s not fully understood how climate change may affect their development.

Núñez Ocasio et al. recently investigated how African easterly waves might behave differently in the future because of climate change. To do this, Núñez Ocasio first developed a new regional weather model configuration that allowed for more realistic representation of possible rainfall extremes. Using this improved model, the team focused on the formation period of the wave that would become 2006’s Hurricane Helene and simulated how the storm might have played out differently in a warmer, more humid environment.

Under a scenario of high greenhouse gas emissions, the researchers found that by the end of the century, waves like the one that became Helene will grow significantly more intense, spinning faster and holding a greater amount of water vapor relative to their surroundings. At the same time, the waves will travel more slowly across Africa. Altogether, this means they will linger for longer periods while dumping heavier rain over affected areas, exacerbating the risk of extreme flooding.

Given that risk, the authors call for the use of high-resolution models like those in the present study to further research how African easterly waves will respond to climate change. Such studies may provide vulnerable communities with the information they need to prepare for extreme weather.

The authors also note that although forecasts with short lead times—the time between a weather forecast and the actual weather event—tend to offer higher accuracy, longer lead times may better account for the slower movement of future African easterly waves. (Journal of Advances in Modeling Earth Systems (JAMES), https://doi.org/10.1029/2025MS005146, 2025)

—Sean Cummings, Science Writer

Citation: Cummings, S. (2025), Warming may make tropical cyclone “seeds” riskier for Africa, Eos, 106, https://doi.org/10.1029/2025EO250468. Published on 19 December 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.

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

Images and audio samples of an eight-foot tall resin sculpture created by singer and artist Jewel, emitting a soundscape informed by ocean data from NASA, were shown at AGU’s annual meeting in New Orleans on 16 December.

“The entire sculpture is entirely data,” Jewel said at a press event where she discussed the piece’s development. Jewel was joined by Chelle Gentemann, program scientist at NASA’s Office of the Chief Science Data Officer, and Kevin Murphy, NASA’s Chief Science Data Officer.

The sculpture and soundscape, together named Heart of the Ocean, will debut at the Venice Biennale in 2026 along with other works by Jewel.

Jewel worked closely with NASA to select data that would translate well into an art piece. The soundscape is constructed with tones, sounds, and a tempo informed by open-source NASA data on the Atlantic Ocean’s wave height, precipitation, salinity, currents, seismicity, and wildlife. Datapoints are translated into a “sound library” created by Jewel that then comes together to form music.

The soundscape “travels” to the deep ocean, slowing as ocean temperatures drop. Then, the piece quickens, and “ascends” to convey ocean surface data. Cloud cover and ocean current data inform how the soundscape moves from one ear to another, simulating a 3-dimensional experience.

 
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“I learned so much,” working with NASA, Jewel said. “It was an incredible intellectual exercise to take that data and not want to alter it,” but still transform it into meaningful music. “I felt I had to be really honest about the data … I wanted it to be pure. I wanted it to be nature, talking to you,” she said.

The soundscape changes in accordance with near real-time Atlantic Ocean conditions, as the data update every 12 minutes. “If it’s raining, the piece looks and sounds different. If it’s stormy, the piece is different. It’s a living instrument that the ocean gets to play in real time,” Jewel said. She particularly likes to experience the piece under full moon conditions.

Jewel hopes the piece raises awareness about the accessibility of NASA data. “It was only because of open data” that she was able to build the piece, she said. 

Gentemann, the NASA program scientist, said the experience was a valued opportunity to explore the artistic side of an otherwise very technically focused career.  

When asked for advice to scientists looking to collaborate with artists, Jewel said: “If there’s an artist that you’re inspired by or a storyteller that you’re inspired by, just reach out.”

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

These updates are made possible through information from the scientific community. Do you have a story about science or scientists? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

The future of the Amazon may rely on its past. According to new research, landscape interventions made by the forest’s pre-Columbian Indigenous inhabitants might still affect the forest’s ecological functions, including its capacity to store biomass, absorb carbon, and withstand climate change.

For centuries, academics believed that the Amazon forest’s poor soil and harsh environment were unsuitable for supporting large and complex prehistoric societies. Before the arrival of Europeans, it was thought, the Amazon was mostly untouched, occupied only by small, nomadic Indigenous groups.

But recent archaeological research, aided by remote sensing technologies such as satellites and lidar, has challenged this idea, revealing extensive pre-Columbian settlements and land modifications throughout the forest. The new findings support the view that Indigenous peoples have actively shaped the forest’s landscape for at least 13,000 years.

Landscape interventions by these early inhabitants included selectively planting and domesticating large forest areas, as well as creating fertile soils known as terra preta, or Amazonian dark earth, by composting organic matter. Some groups even built extensive settlements that left ground marks like mounds and ditches, called earthworks, which are still visible from the sky via satellite and lidar.

In 2023, geographer and remote sensing expert Vinicius Peripato from Brazil’s National Institute for Space Research (INPE) and other researchers published a paper in Science that used lidar and mathematical models to estimate that as many as 24,000 pre-Columbian earthworks could still be hidden beneath the forest’s tree canopies.

Now, Peripato and colleagues have expanded their research to better understand the ecological effects of such large-scale land modifications by ancient forest inhabitants. In a study presented on 18 December at AGU’s Annual Meeting 2025, they used satellite and lidar imagery, along with mathematical models, to compare biomass levels both in areas of the forest where these pre-Columbian modifications were likely to be present and in places where they were not.

A forest reflects different wavelengths of light depending on the structure, density, and height of its vegetation. This property allows researchers to roughly calculate biomass levels in a forest, along with the amount of carbon the forest stores. To refine these estimates, the scientists also used vegetation maps, topographic models, and forest inventory data, providing a global picture of how much biomass the forest stores in 100-meter grids.

Researchers used lidar to image earthworks in Rio Branco in the Brazilian Amazon. From top to bottom, the layers represent the lidar point cloud colored by its height, followed by the terrain slope, hillshade, and elevation of an earthwork, all obtained after the digital removal of the forest. Credit: Vinicius Peripato A More Resilient Forest

Using this combination of methods, the researchers compared the biomass levels in dry and wet parts of the forest from 2010 to 2020. They discovered that within both dry and wet areas, areas with evidence of pre-Columbian management (or areas likely to have had such management based on their predictive models) contained significantly more biomass than untouched regions.

This was true even during extreme weather events, especially in dry areas. In 2010 and 2020, both years marked by severe droughts, researchers found that while the regional biomass average ranged from approximately 65 to 240 megatons per hectare in dry areas, managed portions of the forest in the same regions contained from 70 to 300 megatons of biomass per hectare—about 15%–22% above the regional average.

“The results reinforce the idea that pre-Columbian management practices left a lasting ecological legacy, capable of sustaining greater biomass even under the most severe droughts of the century.”

“The results reinforce the idea that pre-Columbian management practices left a lasting ecological legacy, capable of sustaining greater biomass even under the most severe droughts of the century,” Peripato said.

The researchers observed the same pattern in the forest’s wet regions, though it was more subtle. They found that wet areas contained between 80 and 295 megatons of biomass per hectare in 2010 and about 69–290 megatons per hectare in 2020, whereas the parts of the forest showing evidence of human occupation and landscape management held 72–309 megatons per hectare in 2010 and between 64 and 304 megatons per hectare in 2020—approximately 6% above the regional average.

Examples of managed areas included known archaeological sites, such as monumental earthworks, and more than 2,000 confirmed patches of terra preta.

According to Peripato, these sites provide conditions that make the forest’s vegetation healthier and better able to store more biomass and carbon. “The terra preta soils retain more water and nutrients than other soils, allowing the vegetation to grow more vigorously,” he explained. “In the case of earthworks, water can accumulate in the trenches and ditches left in the soil by the old settlements, also favoring the forest growth.”

The higher an ecosystem’s biomass, the greater its carbon stock is, and the more resilient it is. High biomass levels matter especially during droughts, as they help the forest to retain soil moisture, reducing erosion and the risk of forest fires.

“The managed areas of the forest have a much more fertile soil with a greater capacity to retain water,” said Peripato. “Therefore, these areas are much more apt to resist today’s climatic changes.”

A Legacy for the Future

The researchers argue that understanding the ecological impact of this legacy is crucial to developing effective conservation strategies for the forest. Jean Ometto, a senior researcher at INPE who focuses on the ecological impacts of climate change but was not involved with the study, agreed: “It is important to look at biomass distribution in these ancient sites because it can be a reference measurement for mitigation and adaptation projects, such as restoration and reforestation initiatives.” Ometto also serves as the international secretary with AGU’s Board of Directors.

Ometto, who is involved in a project using lidar to locate new archaeological sites in the forest, emphasized the importance of constructive engagement with local Indigenous populations who continue to live in the forest today and are descendants of the region’s early inhabitants.

“Lessons learned over millennia by these communities can be applied to protect the forest today, increase carbon stocks, and make it more resilient.”

These communities, he noted, still possess knowledge about how to interact sustainably with the forest. “Lessons learned over millennia by these communities can be applied to protect the forest today, increase carbon stocks, and make it more resilient,” he said.

Peripato also believes that the Indigenous legacy of landscape modifications may provide natural climate solutions by preserving biomass, biodiversity, and ecological stability despite modern challenges. He added that the scientific community should consider not only ancient modifications but also those currently promoted by Indigenous communities.

“Many Indigenous communities that live in the forest today still do landscape modifications that might be good for the ecosystem,” he said. “We have to try to understand these communities and how they see and manage the forest. I believe that they already have many of the answers.”

—Sofia Moutinho (@sofiamoutinho.bsky.social), Science Writer

Citation: Moutinho, S. (2025), How ancient Indigenous societies made today’s Amazon more resilient, Eos, 106, https://doi.org/10.1029/2025EO250478. Published on 18 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Volcanoes can erupt in many ways, sometimes blasting plumes of ash and other debris high into the atmosphere or sending rivers of lava downslope.

If an eruption evacuates enough stored magma, the ground overlying a volcano’s reservoir can collapse. The resulting structure, known as a caldera, can be kilometers across and hundreds of meters deep. Caldera-forming eruptions can produce some of Earth’s most hazardous natural phenomena, but they remain in many ways enigmatic despite decades of study.

Enormous caldera-forming eruptions at silicic volcanoes such as Yellowstone are understandably famous. However, collapses at basaltic volcanoes, which erupt less viscous magma and are usually less explosive, can also be highly impactful. Furthermore, basaltic collapses have occurred more frequently in historical times, generally occur more gradually, and can usually be approached more closely than silicic collapses, so they offer important advantages for scientific study.

Since the late 1960s, six caldera collapses are known to have occurred at basaltic volcanoes on land: at Fernandina in the Galápagos Islands (1968), Tolbachik in Russia (1975), Miyakejima in Japan (2000), Piton de la Fournaise on La Réunion (2007), Bárðarbunga in Iceland (2014–2015), and Kīlauea on the island of Hawaiʻi (2018).

Basaltic caldera–forming eruptions present several types of hazards. Clockwise from top left: lava fountains erupt along the rift zone of Tolbachik in Russia in late July 1975; lava flows through populated communities on the island of Hawaiʻi during Kīlauea’s 2018 eruption and caldera collapse; a tephra (ash) plume produced by an incremental collapse event on 19 May 2018 erupts from Kīlauea’s summit; and road damage caused by ground shaking and fault motion in 2018 is seen near the summit of Kīlauea. Credit: Clockwise from top left: Oleg Volynets, Institute of Volcanology, Petropavlovsk, via the Smithsonian Institution Global Volcanism Program, CC BY-NC 4.0; U.S. Geological Survey (USGS) photo by E. Rumpf, Public Domain; USGS webcam photo, Public Domain; USGS photo by K. Anderson, Public Domain

These events have demonstrated that basaltic caldera collapse eruptions can produce complex, cascading sequences of hazards that may occur concurrently over distances of tens of kilometers, with devastating effects on local communities. Hazards include damaging seismicity, ash-rich explosions, gas emissions, and distal eruptions that can discharge lava at hundreds of cubic meters per second for weeks at a time. Residents of the Japanese island of Miyakejima remained evacuated for years after the volcano’s summit collapsed, and the Kīlauea eruption destroyed hundreds of homes in one of the costliest volcanic disasters in U.S. history.

Data collected during caldera collapse eruptions provide unparalleled opportunities to understand some of Earth’s most active volcanoes. The 2018 eruption of Kīlauea was particularly well documented, with extensive observations from real-time monitoring helping to reveal new facets of the volcano’s structure and behavior [Neal et al., 2019]. Such observations have powered leaps in scientific knowledge and inspired renewed focus on understanding caldera-forming eruptions to prepare for and mitigate impacts of inevitable future events [Anderson et al., 2024].

New efforts within the research community are needed to synthesize observations, draw parallels, and identify common physical processes among caldera-forming eruptions. In February 2025, an international and multidisciplinary group of 155 scientists met to address these needs and to provide a springboard for new cross-disciplinary studies. Discussions during that meeting inform the following assessment of what we do and do not understand about this important class of eruption.

Similarities Suggest Common Physics

Comparing observations and interpretations from historical basaltic caldera collapses reveals intriguing commonalities that are remarkable considering the geological contrasts among the volcanoes.

In all six instances, documented collapses were preceded by the lateral intrusion of magma into the crust surrounding summit storage systems. These intrusions propagated as far as tens of kilometers—in many cases feeding fissure eruptions and long-distance lava flows—and in the process drained summit magma and triggered caldera collapses (Figure 1).

Fig. 1. In this conceptual model of basaltic caldera collapse, a dike intrusion and flank eruption withdraw magma from a summit reservoir, which triggers the collapse of the summit caldera that, in turn, sustains the eruption.

In addition, all historical basaltic caldera collapses, with the possible exception of Tolbachik, took place incrementally over days to months through a similar series of abrupt, semiperiodic down drops of the caldera floor (Figure 2). Measurements, where available, show that these incremental collapse events produced magnitude 4–5 earthquakes associated with relatively large amounts of energy at long periods, pushed the ground around the caldera upward and outward, and, in some cases, generated explosive tephra (ash) plumes that rose kilometers into the air.

Fig. 2. During Kīlauea’s 2018 collapse, the ground outside the caldera tilted slowly toward and rapidly away from the caldera as the reservoir depressurized between collapses and was repressurized by collapses, respectively (left axis, black line). The caldera subsided by meters at a time during abrupt collapses (right axis, red line).

These commonalities suggest similar processes. Following the 1968 Fernandina collapse [Simkin and Howard, 1970], a general conceptual model emerged that has since been refined and quantified using observations from subsequent collapses.

In this model, magma withdrawal partially empties a storage reservoir, reducing support for the overlying rock. Eventually, ring faults form in the rock, enabling a pistonlike block to abruptly slip downward into the reservoir under the force of gravity. This subsidence partially repressurizes the reservoir, which stabilizes the piston block and increases the rate of magma outflow, sometimes leading to surges in lava eruption up to tens of kilometers away. Continued magma outflow then reduces reservoir pressure once again, setting the stage for another abrupt collapse event.

Large distal intrusions and eruptions can thus trigger the onset of caldera collapse sequences, which promote further outflow of magma. These sequences explain the large volumes of lava erupted during basaltic caldera–forming eruptions.

Coupled Magmatic-Tectonic Systems

Data collected during caldera collapse eruptions provide unparalleled opportunities to understand some of Earth’s most active volcanoes.

Observations of caldera collapses yield insights that are difficult to glean from more common eruptive activity. One important lesson is that magmatic and tectonic systems can be tightly coupled over an enormous range of spatial and temporal scales and in ways that can result in complex, difficult-to-forecast hazards [Patrick et al., 2020].

For example, at Kīlauea in 2018, magma injection into the volcano’s East Rift Zone triggered a magnitude 6.9 earthquake at the base of the volcano that reduced compressional stress on the rift zone, in turn facilitating increased subsurface flow of magma from the summit into the rift. At Piton de la Fournaise in 2007, the collapse was associated with meter-scale displacement of the volcano’s eastern flank [Froger et al., 2015]. And at Bárðarbunga, the dike that triggered the collapse propagated over a distance of 45 kilometers at a rate and along a direction that were influenced by topography and tectonic stresses [Sigmundsson et al., 2015].

Geophysical and geochemical data collected during collapses can resolve, in unprecedented detail, the locations, volumes, and compositions of magma storage zones, which strongly govern eruptive activity and hazards. Although uncertainties remain, data from the Kīlauea collapse, for example, have placed some of the best constraints on the location and volume of magma storage beneath any volcano.

A scientist samples a lava flow as it crosses a road in Kīlauea’s lower East Rift Zone on 6 May 2018 during the early days of the 2018 eruption and collapse. Credit: USGS photo by K. Anderson, Public Domain

Temporal variations in the composition of erupted lavas demonstrate how fresh magma can mingle with magma stored from decades-old intrusions, influencing eruption rates, dynamics, and hazards. These observations, which can also be used to plumb the hidden pathways between summit magma storage zones and distant eruptive vents, indicate that basaltic rift zones may contain surprisingly large and potentially mobile bodies of magma with a wide range of compositions.

Insights from studying caldera collapses extend beyond volcanology. For instance, despite important differences, slip on caldera ring faults and slip on faults in nonvolcanic settings may be governed by similar physical processes. However, a single caldera collapse sequence may comprise dozens of individual ring fault rupture events, whereas nonvolcanic earthquake cycles often last centuries or longer. Thus, caldera collapse cycles may serve as natural, repeating, field-scale fault-slip experiments, yielding insights into recurrence intervals, fault creep, and the physical properties preceding earthquakes that may ultimately be applicable in places such as the San Andreas Fault [Segall et al., 2024].

The Postcollapse Evolution of Caldera Systems

Many basaltic volcanoes grow through innumerable cycles of caldera collapse and gradual refilling. These decades- or centuries-long cycles (not to be confused with the much shorter incremental collapse cycles during an individual eruption) are integral parts of the long-term evolution of many basaltic volcanoes.

Fernandina caldera, in the Galápagos Islands, collapsed in 1968, dropping by 350 meters, although lava flows and landslide material later filled some of this volume. Benches in the landscape, seen in the foreground and on the opposite side of the caldera in this image taken in January 2001, are evidence of past cycles of caldera collapse and filling. Credit: M. Poland

In contrast to the often fast-paced data gathering conducted during caldera collapses, long postcollapse stretches offer improved opportunities to plan and execute controlled research and to bolster monitoring networks. In the wake of the 2018 eruption at Kīlauea, for instance, congressionally allocated funding has supported important new studies, including the unprecedented deployment of nearly 2,000 seismic stations to resolve the volcano’s subsurface structure, as well as the development of new monitoring and investigative approaches.

Additional insight comes from observations at caldera volcanoes that have not collapsed in historical times despite displaying noteworthy unrest and eruptive activity, such as Ambrym (Vanuatu), Sierra Negra (Galápagos), and Axial Seamount. These observations further elucidate magma storage at caldera systems, dynamic interplays of magmatic and tectonic processes, and conditions required to trigger the onset of collapse.

Caldera collapses are linked with important changes in eruptive activity and hazards.

Caldera collapses are linked with important changes in eruptive activity and hazards. At Kīlauea, major collapses preserved in the geologic record over the past 2,500 years may have led to transitions between centuries-long periods of dominantly explosive and effusive activity [Swanson et al., 2014]. The 2018 collapse was associated with the cessation of a decades-long rift zone eruption and transition to episodic eruptive activity nearer the summit. At Piton de la Fournaise, the 2007 collapse reduced the period of unrest preceding subsequent eruptions, led to an increase in the number of dike intrusions, and increased the proportion of eruptions that occurred near the summit [Peltier et al., 2018].

Although the causes of such transitions are complex and may involve changes in crustal stress and magma supply rate, the effects of collapses on magma storage zones likely play a role. Geochemical analyses of pre- and postcollapse periods indicate that some collapses may strongly affect the structure of shallow magma storage zones (e.g., Kīlauea in 1500, 1790, and 1924), whereas others, such as at Kīlauea in 2018, do not [Lynn and Swanson, 2022]. Similar studies are lacking for many other basaltic caldera volcanoes, such as in the Galápagos, pointing to important avenues for new research.

As magma refills evacuated storage zones, these zones are repressurized, leading to ground deformation, seismicity, and sometimes—as at Bárðarbunga—even reverse slip on caldera ring faults [Glastonbury‐Southern et al., 2022]. Observations of these processes are useful for understanding the geometry and connectivity of magma storage zones, and they shed light on ring fault geometry and mobility.

Open Questions for Future Research

Many fundamental and humbling questions about basaltic caldera collapses remain unanswered, including why some magma intrusions trigger caldera collapse but others do not.

The success of long-standing conceptual models of basaltic caldera collapses suggests that our basic understanding of these remarkable phenomena is solid. Yet many fundamental and humbling questions remain unanswered, including why some intrusions trigger caldera collapse but others do not, what explains variations in collapse sequences among different volcanoes, and why these eruptions end.

We also do not yet know how insights from basaltic caldera collapses are applicable to explosive eruptions and collapses at silicic volcanoes such as Hunga Tonga–Hunga Ha’apai, which in 2022 produced a nearly 60-kilometer-tall ash plume and caused a Pacific-wide tsunami that resulted in several fatalities.

Addressing these questions and improving our ability to forecast basaltic caldera–forming eruptions and mitigate their impacts require improved interdisciplinary collaboration and synthesis of data from historical events. The lessons of the past will find practical application when the next caldera collapse takes place somewhere on Earth.

Acknowledgments

The AGU Chapman Conference on basaltic caldera–forming eruptions was supported by the U.S. Geological Survey (USGS) and the National Science Foundation (NSF EAR grant 2451637). We thank our coconvener, Aline Peltier; AGU conference coordinators Justine Joo and Heather Nalley; all conference participants for their contributions; and observatory scientists and academic investigators around the world for collecting invaluable data during past caldera collapses. Helpful comments were provided by Josh Crozier, Scott Rowland, and an anonymous reviewer. The USGS Additional Supplemental Appropriations for Disaster Relief Act of 2019 (H.R. 2157), signed by the president in 2019, contributed funding to the USGS to support research, recovery, and rebuilding activities in the wake of Kīlauea’s 2018 eruption. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government.

References

Anderson, K. R., et al. (2024), The 2018 eruption of Kīlauea: Insights, puzzles, and opportunities for volcano science, Annu. Rev. Earth Planet. Sci., 52, 21–59, https://doi.org/10.1146/annurev-earth-031621-075925.

Froger, J.-L., et al. (2015), Time-dependent displacements during and after the April 2007 eruption of Piton de la Fournaise, revealed by interferometric data, J. Volcanol. Geotherm. Res., 296, 55–68, https://doi.org/10.1016/j.jvolgeores.2015.02.014.

Glastonbury‐Southern, E., et al. (2022), Ring fault slip reversal at Bárðarbunga volcano, Iceland: Seismicity during caldera collapse and re‐inflation 2014–2018, Geophys. Res. Lett., 49, e2021GL097613, https://doi.org/10.1029/2021GL097613.

Lynn, K. J., and D. A. Swanson (2022), Olivine and glass chemistry record cycles of plumbing system recovery after summit collapse events at Kīlauea volcano, Hawai‘i, J. Volcanol. Geotherm. Res., 426, 107540, https://doi.org/10.1016/j.jvolgeores.2022.107540.

Neal, C. A., et al. (2019), The 2018 rift eruption and summit collapse of Kīlauea volcano, Science, 363, 367–374, https://doi.org/10.1126/science.aav7046.

Patrick, M. R., et al. (2020), The cascading origin of the 2018 Kīlauea eruption and implications for future forecasting, Nat. Commun., 11, 5646, https://doi.org/10.1038/s41467-020-19190-1.

Peltier, A., et al. (2018), Changes in the long-term geophysical eruptive precursors at Piton de la Fournaise: Implications for the response management, Front. Earth Sci., 6, 104, https://doi.org/10.3389/feart.2018.00104.

Segall, P., et al. (2024), Stress-driven recurrence and precursory moment-rate surge in caldera collapse earthquakes, Nat. Geosci., 17, 264–269, https://doi.org/10.1038/s41561-023-01372-3.

Sigmundsson, F., et al. (2015), Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic system, Iceland, Nature, 517, 191–195, https://doi.org/10.1038/nature14111.

Simkin, T., and K. A. Howard (1970), Caldera collapse in the Galápagos Islands, 1968, Science, 169, 429–437, https://doi.org/10.1126/science.169.3944.429.

Swanson, D. A., et al. (2014), Cycles of explosive and effusive eruptions at Kīlauea volcano, Hawai‘i, Geology, 42, 631–634, https://doi.org/10.1130/G35701.1.

Author Information

Kyle R. Anderson (kranderson@usgs.gov), U.S. Geological Survey, Moffett Field, Calif.; Kendra J. Lynn and Ashton F. Flinders, U.S. Geological Survey, Hilo, Hawaii; Thomas Shea, Department of Earth Sciences, University of Hawaiʻi at Mānoa, Honolulu; and Michael Poland, U.S. Geological Survey, Vancouver, Wash.

Citation: Anderson. K. R., K. J. Lynn, A. F. Flinders, T. Shea, and M. Poland (2025), Lessons and lingering questions from collapsing basaltic calderas, Eos, 106, https://doi.org/10.1029/2025EO250471. Published on 18 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Erupting from the vast blue expanse of the Pacific Ocean, the Hawaiian Islands are some of the most isolated landmasses on the planet. Communities and ecosystems there depend on a reliable climate that replenishes freshwater resources through regular rainfall. Unexpected disruptions can have serious impacts.

New high-resolution data from the Hawaiʻi Climate Data Portal have helped hydrometeorologist Audrey Nash at the University of Hawaiʻi at Mānoa draw new connections between rainfall and the activity of the Madden-Julian Oscillation (MJO), a global pattern of wind and moisture that regularly passes over the Hawaiian Islands.

The MJO’s direct impact on precipitation is understudied, and Nash hopes investigating its influence on climate variables in Hawaii could improve future predictions of rainfall. Nash will present her research on 19 December at AGU’s Annual Meeting 2025 in New Orleans.

“Hopefully, when [the MJO influence] becomes more understood, it could be implemented into 2- to 3-day forecasting,” Nash said.

A New Look at Old Data

The MJO is a global system that forms in the Indian Ocean and drifts eastward across the tropics in 30- to 60-day cycles before dissipating and re-forming at its origin point. During “active” phases of the MJO, winds at the surface of the ocean push moisture upward, creating rainfall. “Suppressed” phases occur when winds in the upper atmosphere converge and push downward, creating dry conditions as cool moisture hits warmer air and evaporates.

With the help of Koa, a cluster of computers that can perform large computations, Nash combined multiple available datasets that included decades of information on temperature, wind, humidity, seasonal variations, and other climate variables across Hawaii in her study of the MJO’s patterns.

Taking these known variations into account with the movement of the MJO, Nash uncovered patterns that could be used to improve forecasts: Rainfall decreased significantly in Hawaii when the MJO entered a suppressed phase over the Indian Ocean, while an active phase of the MJO occurring in the western Pacific led to substantial increases in rainfall.

John Bravender, a meteorologist with NOAA’s National Weather Service who was not involved in the research, wrote in an email that Nash’s conclusions align with the bigger picture of MJO activity illustrated by NOAA’s Climate Prediction Center (CPC).

“The benefit of the local study compared to the CPC maps,” Bravender wrote, “is that it provides details in much greater resolution and was validated against observed rainfall.”

The El Niño–Southern Oscillation (ENSO) is a more well-known system that modifies climate factors related to rainfall in Hawaii, with La Niña phases leading to wetter rainy seasons compared to El Niño phases. Nash also evaluated MJO-related rainfall signals in the context of ENSO and found that the signals remained valid across ENSO phases. Evaluating these oscillations together helps inform understanding of abnormally high or low precipitation events.

Forecasting Anomalies

“This research shows us that we may be able to use [the activity of the MJO] to improve our forecasts and preparedness messages during the wet season as well.”

“We’re used to looking at the MJO phase to help anticipate tropical cyclone development or rapid intensification,” Bravender wrote. “This research shows us that we may be able to use [the activity of the MJO] to improve our forecasts and preparedness messages during the wet season as well.”

Bravender also noted that this forecasting could be especially important to people relying on rainwater catchment systems who must decide to opt in or hold off on expensive water deliveries during periods of drought.

Past rainfall anomalies in Hawaii have had devastating consequences. Flooding in Kauai in 2018 affected more than 500 homes and cost $20 million in public property damages, and extreme drought contributed to the catastrophic Lahaina wildfire in 2023. More accurate forecasting of these extreme swings in rainfall could help improve water resources management and emergency preparation on these geographically remote islands.

—Kari Goodbar, Science Writer

Citation: Goodbar, K. (2025), Globe-trotting weather pattern influences rainfall in Hawaii, Eos, 106, https://doi.org/10.1029/2025EO250465. Published on 18 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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 Trump administration is planning to dismantle the National Center for Atmospheric Research (NCAR), one of the world’s leading climate and Earth science research laboratories, according to a statement from Russ Vought, director of the White House Office of Management and Budget, to USA Today. 

Vought called the facility “one of the largest sources of climate alarmism in the country” and said the administration had already started a comprehensive review of activities at the laboratory. 

“Vital activities such as weather research will be moved to another entity or location,” Vought said. 

 

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• Get Involved: Speak Out to Save NCAR Today

The National Science Foundation established NCAR in 1960 as the foundation’s first federally funded research and development center. Among other work, NCAR researchers use both models and observations to study weather, air quality, water management, and solar storms. NCAR’s Derecho supercomputer, housed in Wyoming, allows researchers across the country to run detailed models stimulating phenomena such as cyclones and major wildfires.

Among other innovations, scientists at NCAR invented dropsondes, devices that drop from aircraft to measure pressure, temperature, and humidity during storms. They use models that predict how inclement weather will affect road safety. They are developing a turbulence detection system to allow aircraft to avoid rough spots, working to improve hurricane prediction, and projecting atmospheric conditions months in advance to provide guidance for U.S. military planners.

In a statement shared with Eos, Pamitha Weerasinghe, a science policy professional and director of a campaign to strengthen federal science called Knowledge for a Competitive America, said that the work conducted at NCAR has “formed the scientific bedrock on which modern America was built. To propose ‘breaking up’ NSF NCAR is to ignore the needs of American families and industries, and deny them the information and tools they need to prosper.”

The news comes as international Earth and space scientists, many of whom will likely be affected by the news, gather at AGU’s annual conference in New Orleans. Some took to social media to express their disappointment.

“NCAR is quite literally our global mothership,” climate scientist Katherine Hayhoe wrote on Bluesky. “Everyone who works in climate and weather has passed through its doors and benefited from its incredible resources. Dismantling NCAR is like taking a sledgehammer to the keystone holding up our scientific understanding of the planet.”

NCAR is quite literally our global mothership. Everyone who works in climate and weather has passed through its doors and benefited from its incredible resources. Dismantling NCAR is like taking a sledgehammer to the keystone holding up our scientific understanding of the planet.Unbelievable.

— Katharine Hayhoe (@katharinehayhoe.com) 2025-12-17T02:59:29.336Z

Other scientists expressed similar sentiments.

It is hard to overstate how critical @ncar-ucar.bsky.social is to climate science in the US and around the world. It's the beating heart of our field. Generations of scientists have trained there, and almost everyone I know relies on deep collaborations with NCAR scientists. It's end is unthinkable.

— Kim Cobb (@kimcobb.bsky.social) 2025-12-17T02:50:46.254Z

This is absolutely insane and so incredibly shortsighted. NCAR is a global pillar for all atmospheric science and holds the highest of standards for research excellence. We collaborate with NCAR; source data from them; they pioneer scientific breakthroughs.This must not go quietly.

— Brian Matilla (@bxmatilla.bsky.social) 2025-12-17T05:25:14.802Z

As someone not with NCAR, I use NCAR-based software everyday to help identify and track regions of excessive precipitation to help NWS forecasters protect lives and property. NCAR is extremely valuable and we need them.

— Noah Brauer (@noaabrauer.bsky.social) 2025-12-17T04:16:52.073Z

NCAR is home to about 830 employees, but it is not clear how many employees or programs the dismantling will affect. According to a senior White House official who spoke to USA Today, the effort will begin immediately, and includes closing the center’s headquarters: the Mesa Laboratory in Boulder, Colo. The official also flagged several programs the administration considers wasteful, such as efforts to make the sciences more inclusive and research into wind turbines.

In a 16 December statement posted on the NCAR website, Antonio Busalacchi, president of the University Corporation for Atmospheric Research, which manages NCAR, said the center was aware of the Trump administration’s proposal, but had not received additional information.

“NSF NCAR’s research is crucial for building American prosperity by protecting lives and property, supporting the economy, and strengthening national security,” he wrote. “Any plans to dismantle NSF NCAR would set back our nation’s ability to predict, prepare for, and respond to severe weather and other natural disasters.”

In a livestream about the news on Wednesday morning, weather and climate scientist Daniel Swain said NCAR is set to be dismantled for “reasons that do not align with the interests of Americans, which do not align with the interests of really anybody, anywhere in the world.”

“I think this is the moment to be reaching out to your lawmakers and speaking with journalists about the value of NCAR and what would be lost, what will be lost, if the current plan is fully put into motion,” he said.

To voice your support for NCAR, visit this AGU page, where you can find email text and a call script to share with your representatives.

—Emily Gardner (@emfurd@bsky.social), Associate Editor, and Grace van Deelen (@gvd.bsky.social), Staff Writer

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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It’s now become easier to forecast the next eruption of Alaska’s Bogoslof volcano.

New research led by Pavel Izbekov, a volcanologist at the Alaska Volcano Observatory, is applying the foundations of diffusion chronometry—the study of chemical change in crystals over time—to a new eruption forecasting approach. Izbekov’s team used crystal clusters and their collective records of magma to date and discern the cause of the 2016–2017 Bogoslof volcanic eruption.

They found that around 180 days before the eruption, the volcano experienced a rapid ascent of magma to a shallow storage chamber under the surface of the volcano, where it accumulated until it erupted. These findings can be used in tandem with other monitoring methods to more accurately anticipate the next eruption at Bogoslof and other volcanoes.

“Understanding how [volcanoes] work, understanding what precedes an eruption, and the ability to forecast volcanic behavior is extremely important for our safety,” Izbekov said. The team presented their findings on 17 December at AGU’s Annual Meeting 2025 in New Orleans.

Crystal Clusters as Clocks

A volcanologist reconstructing the history of magma with zone records is “like a forensic detective trying to figure out a crime scene in a crystal,” said Hannah Shamloo, a volcanologist at Central Washington University who was not involved in the new research.

A volcanic crystal grows from its core outward, developing concentric zones each time it experiences a major event. Visible under an electron microprobe, the zones resemble a tree’s growth rings, which capture the chemical reactions spurred by a particular event. The innermost zones near the crystal’s core reflect early life events, while the outermost zones along the rim depict activity later in life.

“If you look at the pair [of crystals], which responded to the same event simultaneously, well, we’re in business.”

The challenge is that multiple events can yield the same chemical reaction within a zone. To eliminate competing possible causes of the Bogoslof eruption, Izbekov and his colleagues looked not just at one crystal, but at a cluster of crystals of different types. If volcanologists look not just at the plagioclase, whose zone records they can attribute to a few possible explanations, but also at a clinopyroxene, whose zone records point to a different set of explanations, they can find a common denominator by the process of elimination.

“If you look at the pair, which responded to the same event simultaneously, well, we’re in business. This is the beauty of this new approach,” Izbekov said.

From Past to Future

Bogoslof was an optimal case study for cluster chronometry because the magma in its chamber below the seafloor is rich in crystals that record clear responses to pressure and temperature changes.

The team analyzed plagioclase-clinopyroxene-amphibole clusters within samples of basalt that erupted from Bogoslof in August 2017, toward the end of a 9-month eruption period. The conjoined crystals shared zone boundaries, indicating that they experienced the same events in the magma chamber.

One event stood out because the three minerals responded very differently: The clinopyroxene crystals suddenly decreased in magnesium content, the plagioclases decreased in anorthite content, and the amphiboles stopped growing. Izbekov and his team determined that decompression, a rapid drop in magmatic pressure that happens when magma ascends toward the volcanic surface, is the best explanation for all three distinct responses across the crystals’ zones.

Now, when a seismometer picks up signs of decompression at Bogoslof, a roughly 180-day countdown until eruption can begin.

The researchers then attempted to date the decompression event and found that it happened no more than 180 days prior to the end of the second eruption in August, around early March 2017. They validated their detective work in the cluster investigation by comparing their results with those from established geochemical monitoring methods. Monitors had picked up higher seismic activity and sulfur dioxide emissions—two indicators of magma’s ascent through the crust and the corresponding drop in pressure—at Bogoslof in March 2017, which supported the team’s findings.

In the future, when a seismometer picks up signs of decompression at Bogoslof, a roughly 180-day countdown until eruption can begin—if an eruption happens when expected, it would further validate the diffusion chronometry technique.

Predictive Power of Crystals

Shamloo was encouraged by the results but cautioned that there was still much to decipher about how crystals record a volcano’s inner workings.

“There’s a lot that can happen to the crystal record that can confuse a geologist,” Shamloo said.

The temperature of the magma at the point of diffusion is one of those confusing, yet essential, components. While the exact temperature of the basalt is unknown, Izbekov and his colleagues “did a careful job handling their assumptions for their model to minimize uncertainty,” Shamloo said.

“I do think relying on the crystal record in general is becoming a useful ‘monitoring’ tool for volcanoes,” Shamloo said. “There is power in reading the crystal record to really understand eruptive histories and potentially how a volcano will erupt in the future.”

—Claudia Steiner (@claudiasteiner.bsky.social), Science Writer

Citation: Steiner, C. (2025), Crystal clusters contain clues to magma’s past and future eruptions, Eos, 106, https://doi.org/10.1029/2025EO250475. Published on 17 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Years before the first telescope was invented, sky-gazers made their rooms into pinhole cameras and took pen to paper, drawing the Sun and the little dark spots that moved across its face day by day. Sunspot drawings date back more than 2,000 years to astronomers in ancient China and, many centuries later, to Western scientists like Galileo and Kepler.

Now science historians worldwide have come together to compile and digitize 400 years’ worth of sunspot drawings in the hopes of illuminating solar activity of the past and informing our present understanding. Solar physicist Andrés Muñoz-Jaramillo used this digitized collection of sunspot observations to develop a collection of software tools to analyze solar cycles and reconstruct missing gaps.

“When we think about how much our capability of observing the [solar] cycle has evolved during the past decades—it’s incredible,” said Muñoz-Jaramillo, a senior research scientist at the Southwest Research Institute in Boulder, Colo. “The quality, resolution, cadence, everything.”

Learning from the Past

Solar cycles typically last 11 years, but Muñoz-Jaramillo said that the best instruments for observing the Sun, like the Parker Solar Probe and the Solar Dynamics Observatory, have been around for only about 2 decades. To understand solar variability going back centuries, researchers must look to techniques of the past.

“Whenever we’re dealing with long-term variability, we don’t have the luxury of waiting 100 years to get better data,” said Muñoz-Jaramillo.

Before the invention of the photograph, astronomers would point a solar telescope at the Sun and use the eyepiece to project the image upon a surface covered with paper. They would sketch the sunspots they observed that day and denote the time and date. Over time, the spots appeared to move across the page and grow or shrink or change shape. Some of these records of solar activity have survived to the present day, often gathering dust in neglected corners of archives.

Historians have been diligently collecting and digitizing centuries of drawings and creating detailed logs of the position and size of spots over time. Researchers are now using these logs to study the long-term variability of the Sun.

“A huge part of this work is done by our historian friends. They are like detectives.”

“A huge part of this work is done by our historian friends. They are like detectives,” said Muñoz-Jaramillo. “The real heroes are those that went from archives to basements and traveled all over the world and talked with people, convinced them to let them in, allowed them to take pictures.”

But hundreds of years’ worth of data are difficult to handle. So Muñoz-Jaramillo and his colleagues developed a computational framework to support the efforts of solar cycle researchers worldwide. This collection of software tools uses Bayesian statistics to fill in the gaps where sunspot data may not be available.

“You can make these statements now in a probabilistic way about what went on in these historical periods,” said Muñoz-Jaramillo.

The researchers used this new framework to learn more about the Maunder Minimum, a time period in the 15th century when the Sun was less active and very few sunspots were observed—a few dozen in comparison to the tens of thousands typically observed. With so few data points, any additional information can help scientists better understand the solar activity of the time, Muñoz-Jaramillo said. They also examined another slow activity period in the late 16th century called the Dalton Minimum and compared recent solar activity to that of previous centuries.

Using this framework, they learned that the Maunder and Dalton Minima might have been preceded by other cycles with deep minima in solar activity spread far apart in time. Some heliophysicists speculate that there may be entire solar cycles’ worth of observations missing, Muñoz-Jaramillo said.

Muñoz-Jaramillo and his colleagues presented these results on 16 December at AGU’s Annual Meeting 2025 in New Orleans.

Spotting the Sun’s Evolution

Solar cycle researchers typically observe cycles with what are known as butterfly diagrams, plots of the time and latitude of sunspots. These plots can be used to understand the long-term variability of the Sun by comparing modern and historic data and noting parallels between them. Researchers can reconstruct past solar cycles using this new computational framework and can analyze them using butterfly diagrams to better understand how the Sun has changed in recent centuries.

“It’s a service to the community. We put all these things together to make it easier for any modern scientist to work with.”

“This study is highly innovative because, until now, reconstructions of past solar activity have relied solely on sunspot counts,” José Manuel Vaquero Martínez, a physics professor at the Universidad de Extremadura who was not involved in the study, said in an email. “In contrast, this approach incorporates not only the number of sunspots but also their positions. In other words, it leverages our understanding of how solar active regions (in this case, sunspots) evolve to reconstruct past solar activity.”

The team hopes their work will enable researchers to tap into the treasure trove of historical data more easily than before, Muñoz-Jaramillo said. “It’s a service to the community. We put all these things together to make it easier for any modern scientist to work with.”

—Daniella García Almeida, Science Writer

Citation: García Almeida, D. (2025), Sunspot drawings illuminate 400 years of solar activity, Eos, 106, https://doi.org/10.1029/2025EO250477. Published on 17 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: AGU Advances

Earth system models offer insight into how climate change will affect communities. But residents of those communities are rarely consulted on the design and deployment of these models, which can lead to the models being misused in local decisionmaking. To bridge this divide, Cheng et al. collaborated with Indigenous communities in two regions to model the effects climate change will have on their land.

In the Arctic Rivers project, the researchers worked with Indigenous communities across Alaska to model how climate change will alter rivers and streams. In the Mid-Klamath project, the researchers worked with the Karuk Tribe in Northern California to study how different wildfire management strategies would affect local hydrology.

In both cases, mismatches existed between the methodology available to the researchers and the needs of the end users, and the collaborators mitigated these mismatches to varying extents. In the Arctic Rivers project, for example, constraints on computational resources limited the number of future scenarios the researchers could model. Thanks to involvement from the project’s own Indigenous Advisory Council and the Yukon River Inter-Tribal Watershed Council, the researchers were able to prioritize the scenarios most relevant to the communities.

In the Mid-Klamath project, on the other hand, misunderstandings at the start of the project led the researchers to choose a modeling tool that didn’t fully meet the expectations of the tribe. More extensive discussions during early stages of the project could have avoided this issue, the researchers noted, and the National Science Foundation has recently begun to change its granting system to allow for these early discussions.

Accurately communicating the limits of the available technology is crucial, the researchers wrote. For example, one member of an Alaskan community stated that conditions in the region were changing so quickly that they needed subseasonal projections in addition to decade-scale projections. Unfortunately, the former were beyond the technical expertise of the scientists involved in the project. But scientists were careful not to mislead the community into thinking such a thing was possible in that project.

Cultural humility and spending ample time with Indigenous communities are both cornerstones of successful collaborations, the researchers wrote. At the same time, it’s important to acknowledge the capacity constraints that many scientists face. In addition, it is valuable to offer roles involving reasonable time commitments to scientists with fewer resources, so as not to exclude them from the codesign process. (AGU Advances, https://doi.org/10.1029/2025AV001921, 2025)

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

Citation: Sidik, S. M. (2025), Climate modeling for communities, with communities, Eos, 106, https://doi.org/10.1029/2025EO250473. Published on 17 December 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
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NOAA released this year’s Arctic Report Card on 16 December at AGU’s Annual Meeting 2025 in New Orleans. The report gives an update on changes to the region’s climate, environment, and communities and documents these changes for future scientists looking to the Arctic’s past.

In 2025, parts of the Arctic experienced record-breaking temperatures, low sea ice extent, and other extreme climate events. Credit: NOAA’s Arctic Report Card 2025

After 2 decades of the U.S. government producing the annual report, however, datasets and resources used to create it may be under threat as federal science agencies lose staff and plan for funding uncertainties.

“There is growing concern over how the U.S. will be investing in Arctic research,” said Matthew Druckenmiller, an Arctic scientist at the National Snow and Ice Data Center and lead editor of the report.

Another Year of Arctic Records

From October 2024 to September 2025, the time period analyzed by the report, Arctic surface air temperatures were the warmest on record. The past year in the Arctic marked the region’s warmest autumn, second-warmest winter, and third-warmest summer ever.

This year, the Arctic also had the most precipitation ever recorded, with its wettest spring on record and higher than normal winter snow cover. “To see both those records [precipitation and surface air temperature] set in a single year was remarkable,” Druckenmiller said.

Seasonal surface air temperature anomalies (in °C) for (a) autumn 2024, (b) winter 2025, (c) spring 2025, and (d) summer 2025. Temperature anomalies are shown relative to their 1991–2020 means. Hatching indicates the warmest seasonal temperatures since 1940. Source: ERA5 reanalysis air temperature data were obtained from the Copernicus Climate Change Service. Click image for larger version. Credit: NOAA’s Arctic Report Card 2025

Sea ice in the Arctic continues to hit new lows: Maximum sea ice extent this winter was the lowest observed in the 47-year satellite record. As sea ice shrinks, the Arctic becomes less reflective, exacerbating climate change as the region absorbs, rather than reflects, more heat from the Sun. Ice on land also continues to melt—the Greenland Ice Sheet lost mass in 2025, as it has every year since the late 1990s.

As the region warms, the Arctic Ocean and associated waterways are changing, too. “Atlantification,” a northward intrusion of warm, salty water from the Atlantic, is altering the Arctic Ocean, leading to decreased winter sea ice and creating conditions for more frequent algal blooms. How this influx of water will affect ecological communities in the Arctic remains one of the biggest unanswered scientific questions about the Arctic, said Igor Polyakov, an oceanographer at the University of Alaska Fairbanks and coauthor of the report.

Data Difficulties

Data included in the report are collected by the Arctic Observing Network (AON), an internationally coordinated system of data observation and sharing.

But obstacles impede the system’s ability to monitor the Arctic, according to report authors. Sparse ground-based observation systems, unreliable infrastructure, limited telecommunications, and satellites operating beyond their mission lifetimes are hindering data collection and sharing. “Persistent gaps limit the AON’s ability to fully support Arctic assessments and decision-making,” the authors write.

Science agencies such as NOAA, NASA, and the National Science Foundation and the Interior Department contribute significantly to AON, but all faced staff and budget reductions in 2025. These changes could affect AON and its ability to publish the Arctic Report Card, “jeopardizing long-term trend analyses and undermining decision-making,” the authors write.

Though the Arctic Report Card team received “great support” from NOAA and the report was successfully published, “there were some difficult moments this year,” Druckenmiller said.

“Data doesn’t interpret itself.”

In particular, the shutdown of climate.gov, the NOAA website that housed most of its climate science information, slowed the team’s ability to create the report’s graphics. The federal shutdown in October and November delayed the processing of key datasets, notably one from NASA that documented surface air temperature.

In addition, the report points out that federal budget proposals for 2026 may affect multiple datasets and observation systems used in the report. The three primary sea ice–observing systems (CryoSat-2, Soil Moisture and Ocean Salinity (SMOS), and Ice, Cloud, and land Elevation Satellite 2 (ICESat-2)) are all operating past their mission lifetime, as well. And in July, the Department of Defense decommissioned its Defense Meteorological Satellite Program, which tracked meteorological, oceanographic, and solar-terrestrial physics in the Arctic and elsewhere.

“When these long-standing data products are decommissioned, you really lose a lot of data continuity, which is really important if you’re going to accurately document long-term trends,” Druckenmiller said.

Losing expert scientists at federal science agencies, labs, universities, and research institutions will likely pose challenges, too, he added. “Data doesn’t interpret itself.”

Indigenous-Led Data Collection

Rapid changes to the Arctic are stressing the human communities there: Permafrost thaw releases potential toxicants into drinking water, wetter weather contributes to flooding, and changes to snowfall and ice affect travel. The remnants of Typhoon Halong brought extreme winds and surging water to Alaska’s southwestern coast in October 2025, flooding communities and forcing more than 1,500 residents to evacuate.

Data give these communities—many of which are majority Indigenous—a better ability to respond to climate change, and a weaker AON could impede flood prediction and community adaptation plans, the report states.

As the availability of federal data and resources remains uncertain, Indigenous-led monitoring networks highlighted in the report have provided another model.

Sentinels from the Indigenous Sentinels Network and two NOAA officials conduct surveys on northern fur seal rookeries on St. Paul Island, Alaska. Credit: Hannah-Marie Ladd, NOAA’s Arctic Report Card 2025

The Indigenous Sentinels Network, for example, is a tribally owned and operated cyber infrastructure system supporting Indigenous-led environmental monitoring. Sentinels collect observational data on a range of environmental systems, from wildlife to coastal erosion to tundra greening. The data collected are governed by the communities that collect them and used locally for decisionmaking, collaborative research projects, and climate adaptation planning.

The Building Research Aligned with Indigenous Determination, Equity, and Decision-making (BRAIDED) Food Security Project, another example of an Indigenous-led monitoring project, tracks mercury in locally harvested foods to ensure food safety. All the samples are processed and tested locally on St. Paul Island in Alaska.

“These are models that can be used for resilience everywhere.”

This type of place-based, community-led monitoring is “foundational to understanding and responding to rapid change” facing the Arctic, said Hannah-Marie Ladd, program director for the Indigenous Sentinels Network and author of the new report.

“Indigenous-led monitoring can, and always has, complemented federal science by providing year-round, place-based observations that are often missing” from short-term field seasons, she said. “[Sentinels] live in these environments, and they can detect changes earlier and interpret them with cultural and ecological context that is often missing when outside entities come into a new relationship with a place.”

Such a framework will become only more valuable as the Arctic, and the rest of the world, warms. “These are models that can be used for resilience everywhere,” Ladd said.

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

Citation: van Deelen, G. (2025), Amid the Arctic’s hottest year, Arctic science faces a data deficiency, Eos, 106, https://doi.org/10.1029/2025EO250482. Published on 16 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Extreme wildfire events are becoming more frequent globally, a pattern that carries a risk for human health. Inhaling smoke from fires can send small bits of particulate matter into airways, aggravating asthma and decreasing lung function. But another, far less understood danger is hitching a smokey ride alongside these aerosols: fungi.

Researchers are increasingly recognizing how wildfire smoke can scatter microorganisms like fungi into the air. This phenomenon is part of a budding field called pyroaerobiology, explained Leda Kobziar, a wildland fire scientist at the University of Idaho in Moscow who has been studying the relationship between airborne spores and wildfire smoke since 2018.

New research from Kobziar’s team has confirmed that smoke-borne fungal spores can cause lung disease in mice. Her team took smoke samples from wildfires, isolated the fungal species within them, and exposed mice to these samples. Many of the mice soon showed symptoms of lung disease. The team will present its findings on 16 December at AGU’s Annual Meeting 2025 in New Orleans.

Catching Fire

“It was really an unknown that there were living microorganisms in wildland fire smoke. I think most people assumed that it was sterile because it comes from a hot fire.”

Studying the living side of smoke is a relatively new practice. “It was really an unknown that there were living microorganisms in wildland fire smoke. I think most people assumed that it was sterile because it comes from a hot fire,” said Phinehas Lampman, a former wildland firefighter, coauthor on the study, and wildland fire scientist at the University of Idaho.

The first study exploring the problem was published in 2004 by then–high school student Sarah Mims and her father, who used a smoke detector attached to a kite to collect fungal samples and correlate them with smokey days.

While there are more pyroaerobiologists today than there were 20 years ago, there are still many unanswered questions about what, how, and to what effect fungal spores travel with smoke.

For the new study, Kobziar, Lampman, and their team developed drone-based sampling systems to collect fungal samples and record conditions like temperature and humidity in wildfire smoke. Over a period of 4 years, the team conducted more than 100 drone flights into grassland and conifer forest fires across nine different areas, including sites in Utah, California, Kansas, and Florida.

A majority of the sampling was done at prescribed burns intentionally set by firefighters to reduce wildfire hazard. The controlled nature of prescribed burns allowed the researchers to get up close to fires and better maneuver their drones for sampling.

The team found that wildfire smoke from the prescribed burns contained spore concentrations of up to 400,000 spores per cubic meter, 4 times higher than the threshold that has been shown to decrease lung function.

To find out whether the fungal species present in smoke pose a health risk, the team used spores from the smoke samples to grow and isolate fungal colonies. They found 110 unique fungal taxa, 9 of which were identified to be potential human pathogens.

The researchers then exposed mice to these isolated samples. Over the course of a few weeks, the animals developed symptoms of lung disease in response to three different fungal taxa, suggesting that some fungi in wildfire smoke have the potential to negatively affect human health as well.

Exploring Health Impacts of Fungi in Smoke

Prescribed burns typically burn the same biomass as wildfires, so the composition of fungi in the smoke is likely similar. “But wildfires have a very different size footprint and typically generate a lot more power,” Kobziar said, explaining that large natural fires have the potential to generate much more advection of air and carry more diverse microbes.

Clouds of wildfire smoke with large distributions can act as vectors and scatter potentially dangerous fungi into new areas, said coauthor Borna Mehrad, a pulmonologist at the University of Florida in Gainesville.

“As fires become more frequent, this will become a progressively bigger issue. It’s something that we as physicians hadn’t even considered.”

“As fires become more frequent, this will become a progressively bigger issue,” he said. “It’s something that we as physicians hadn’t even considered.”

Despite the concerning finding, it’s important to note that not all fungi dispersed by wildfire smoke are a concern for human health, said Jennifer Head, an epidemiologist at the University of Michigan in Ann Arbor who was not involved in the new research. “The species of fungus matters a lot in terms of what is the risk posed to human health.” She stressed the need for future research to characterize which fires, and where, are most concerning as vectors for dangerous fungi.

Looking forward, the team seeks to differentiate the various causes of lung disease and uncover what proportion of negative health effects are caused by smoke-borne fungi. The team hopes their findings could help protect people on the frontlines of major burns, like wildland firefighters.

“This is really just the opening of the box of discovery,” Kobziar said.

—Alonso Daboub (@AlonsoDaboub), Science Writer

Citation: Daboub, A. (2025), Fungal spores in wildfire smoke could cause lung disease, Eos, 106, https://doi.org/10.1029/2025EO250470. Published on 16 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

During the ninth century BCE, King Mesha reigned over Moab, a kingdom located in what is now Jordan. Details of how King Omri of Israel ruled the Moabites, Mesha’s subsequent rebellion, and numerous construction projects Mesha undertook as monarch were recorded on a slab of stone around 840 BCE.

The Moabite Stone, found in 1868 in modern-day Dhiban, Jordan, and now on display at the Louvre Museum in Paris, tells a story seemingly contemporaneous with one from the biblical Book of Kings, but from a different perspective. Artifacts that illuminate biblical times hold great importance for archaeologists, museums, and collectors—so much that forgeries fetch great sums.

Artifacts from the biblical era are so valuable that in one infamous example, an entire class of reproductions, the Moabite forgeries, was created soon after the discovery of the Moabite Stone. The Moabite forgeries consist of clay vessels, figurines, and other items crafted in the 19th century. Some are inscribed with Phoenician script selected from the real Moabite Stone. The inscriptions on the Moabitica, as the forgeries are called, translate to nonsense, and the clay used to fashion the frauds came not from Jordan but from clays around Jerusalem.

This photograph of Moabitica pottery, a known forgery, features symbols written in Phoenician that translate to nonsense. This particular piece has been sampled for future paleomagnetic analysis. Credit: Published with the permission of the Institute of Archaeology of the Hebrew University of Jerusalem; photo by Mimi Lavi, Conservation Lab. Eos thanks Daphna Tsoran, Curator of the Collection Room at the Institute of Archaeology of the Hebrew University of Jerusalem, for permission to access this object.

The Moabite forgeries and other fakes can be used to validate ways to authenticate archaeological finds. In a pair of studies that will be presented at AGU’s Annual Meeting 2025, Scripps Institution of Oceanography postdoctoral scholar Yoav Vaknin will explore ways to verify archaeological finds using something that’s hard to imitate—Earth’s paleomagnetic field.

A Record in Clay

Earth’s magnetic field, which has both a direction and a strength, changes over time. North and south swap poles every so often. The intensity of the field—how strong it is at a particular location or at a particular time—also rises and falls.

“You can use these changes as a dating tool for archaeology,” explained Vaknin. “But first, you need to know how it changed over time.” To that end, Vaknin and colleagues had previously conducted a study compiling paleointensity measurements of the magnetic field for well-dated antiquities at the time they were produced, painstakingly reconstructing how the intensity changed in and around the Levantine region.

“We can use this reconstruction of the field to date [an] object.” This technique is also how forgeries can be detected.

“Artifacts are known to be really good magnetic records in part because they’re fired to really high temperatures,” said Courtney Sprain, a paleomagnetist at the University of Florida who was not involved in this study. In the kilns and ovens that harden clay, temperatures can reach 1,200°C (2,192°F). At these temperatures, chemical reactions cause new minerals to form, including iron-rich magnetite that locks in the status of Earth’s magnetic field—both direction and intensity—at around 580°C (1,076°F). Because pots don’t remain in place after they’ve been fired, the direction isn’t especially useful. But the magnetic field’s intensity is.

A marked increase in magnetic field intensity, more than twice that of today’s field, took place in the Levant from about 1050 to 700 BCE. Called the Levantine Iron Age anomaly, it has been documented across the region, recorded in artifacts and rocks from Cyprus, Israel, Jordan, Syria, and other locales.

Because the paleointensity timeline has been established for the region, “if we have materials that aren’t well dated, we can use this reconstruction of the field to date [an] object,” Vaknin said. This technique is also how forgeries can be detected.

Real or Fake

The Iron Age overlaps with much of the biblical period, Vaknin said. This is the time when many of the Bible’s stories—like those of King Mesha and King Omri—took place.

This time is an important part of human history, so people want these artifacts. As a result of this demand, Vaknin said, “they’re worth a lot of money.”

If an artifact comes to or from an antiquities market, private collection, or museum without information about the archaeological dig where it was excavated, “we don’t know how it got there,” said Vaknin. “There isn’t a method that’s really 100% secure to say if something is authentic.”

Researchers often disagree in their assessments of authenticity, with debates spilling into the academic literature about whether important items are legitimate or mere imitations.

If the artifact looks like it came from this time but has a magnetic field of today, “then it’s clearly fake.”

Measuring the paleomagnetic intensity of a disputed artifact can help archaeologists determine whether the artifact was made recently or during a time with a distinctly different paleomagnetic field than today’s. For instance, in Vaknin’s work, he demonstrates that forgeries were clearly fired at a time with today’s magnetic field intensity—not at the time of the Levantine Iron Age anomaly. If the artifact looks like it came from an earlier time but has a magnetic field of today, “then it’s clearly fake,” Vaknin said.

With this proof of concept, Vaknin and his colleagues have begun to look at artifacts of unknown authenticity that are under vigorous debate.

One limitation of the method is that it works only for authenticating artifacts from times when the paleomagnetic field was very different from the modern field, Vaknin cautioned. He and his colleagues are addressing that limitation by combining novel modeling and experiments related to how the magnetization of an item of interest can detectably change at low temperatures—the topic of another AGU25 presentation.

“This is one of the really cool examples of where [paleomagnetic] data can help with the study of archeology in general,” said Sprain regarding Vaknin’s work on using paleointensity. “Any artifacts that were from this area [and] from that time period, they have to have this strong magnetic signal.”

—Alka Tripathy-Lang (@dralkatrip.bsky.social ), Science Writer

Citation: Tripathy-Lang, A. (2025), Credible or counterfeit: How paleomagnetism can help archaeologists find frauds, Eos, 106, https://doi.org/10.1029/2025EO250449. Published on 16 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

Yesterday, I posted about the landslide disaster that struck Malalak in Sumatra at the end of November 2025. Unfortunately, that is just a tiny component of the catastrophe that has occurred in this part of Indonesia.

The BGS has used imagery released under the Disaster Charter to map landslides triggered by this event in Sumatra – their map shows a lower estimate of 4,326 landslides, but this is a massive underestimate:-

British Geological Survey map of landslides triggered by the November 2025 rains in Sumatra.

This is a dramatic image, and the BGS have done a great job to compile this map, but it covers just a small part of the affected area (Malalak is not in this part of Sumatra), and the mapping does not capture all of the landslides. For example, the southern banks of Takengon Lake, in the centre of the image, has no mapped landslides. However, this is how that area looked on the 30 November 2025 Planet Labs PlanetScope satellite image (the centre marker is at [4.57347, 96.87513]:-

Landslides on the southern side of Lake Takengon in Sumatra triggered by the November 2025 rains. Image copyright Planet Labs, used with permission, collected on 30 November 2025.

This is a classic situation that I have described repeatedly in recent years – intense rainfall triggering hundreds of thousands of shallow landslides, which then form channelised debris flows. Take a look at the area on the immediate banks of the lake. This is this area as of 28 October 2025 and on 29 November 2025:-

Planet Labs images from 28 October 2025 and on 29 November 2025 (https://www.planet.com/).

Note the devastation that the channelised flows have inflicted on the communities. This pattern is replicated over a massive area of Sumatra. I wonder if this is the largest landslide event on record in terms of the number of individual failures, surpassing even Cyclone Gabrielle in New Zealand.

Loyal reader Alasdair MacKenzie kindly highlighted that there is some footage of the debris flows at Malalak on social media:-

Acknowledgement

Thanks as always to Planet Labs (2025) for their amazing imagery.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Located in the western portion of the Brazilian Amazon, Terra Indígena do Vale do Javari (Valea do Javari Indigenous Land) is one of the world’s largest continuous patches of pristine tropical rainforest and harbors the world’s highest concentration of noncontacted Indigenous peoples.

The region gained global attention in 2022 with the assassinations of Brazilian anthropologist Bruno Pereira and British journalist Dom Phillips. The murders revealed the increasing pressure locals face in preserving the environmental and cultural integrity of their way of life and staving off the organized crime that often accompanies illegal logging and poaching in the region.

Wildfires are contributing to this pressure, and researchers are using innovative mapping techniques to try to understand their dynamics within the territory and its surroundings. A team of biodiversity and remote sensing experts based in Brazil and the United States will present some of their findings on 16 December at AGU’s Annual Meeting 2025.

Mapping wildfires around the still-pristine region may help identify priority areas for conservation and inform policy planning in forest protection, said coauthor Gabriel de Oliveira, a remote sensing and vegetation dynamics researcher with the University of South Alabama.

“Our goal was to understand whether the forest’s natural resistance to fire has held firm over 4 decades and how pressures in the surrounding landscape might be changing that,” said de Oliveira.

“Vale do Javari is certainly a highly threatened region because it is far from everything and very much at the mercy of organized crime.”

The team used MapBiomas Fire Collection data, which record the annual and monthly mapping of burned areas in Brazil from 1985 to 2024. They supplemented these data with additional satellite-derived thermal information to map where fires have occurred since 1985 inside Vale do Javari and surrounding buffer zones extending 50, 100, and 200 kilometers outward.

Researchers who study fire in the Amazon see this ongoing study as a valuable brick in the growing wall of knowledge about fire in protected lands. “They’re using MapBiomas data to see what has burned and how often it burned,” said Ane Alencar, science director at the Amazon Environmental Research Institute (IPAM Amazônia).

“Vale do Javari is certainly a highly threatened region because it is far from everything and very much at the mercy of organized crime. Any tool or study that reveals the threats facing that Indigenous land is very valuable, so it looks quite interesting,” she added.

Ultimately, de Oliveira hopes the new research will help inform conservation strategies in the area. “If we could detect where fire is already recurring or creeping closer, we could begin to identify zones that deserve urgent attention from policymakers,” he said.

Finding Patterns

Fires have become a growing concern in isolated Indigenous lands across the Amazon.

According to a recent analysis by the Observatory of Isolated Indigenous Groups, the past 25 years of satellite data show that in 2024, more than 10,000 hot spots (burn scars) were detected in Brazil alone. The analysis was conducted between January and September across 67 Indigenous territories and protected areas with isolated groups and represents both a 221% increase above the long-term average and a roughly 50% increase from its previous peak in 2010.

The landscapes of Indigenous and protected areas are typically less disturbed compared with the rest of the Amazon, so an abrupt spike in hot spot activity signals processes that researchers say deserve close attention.

A similar pattern emerges when considering not just the number of hot spots but their scope, the total area burned within Indigenous lands across Brazil. For most of the past decade, that figure remained around 1.5 million hectares per year. But in 2024, during one of the most severe droughts on record, total burned area inside Indigenous territories jumped to about 3 million hectares, an increase of 81%, according to IPAM Amazônia. Nearly a quarter of all area burned in the Amazon in 2024 occurred within Indigenous territories.

For researchers who study territories such as Vale do Javari, these trends are troubling not only because they indicate rising fire pressure but because Indigenous lands play critical roles in ecology and public health. A 2023 study showed that Indigenous territories act as major buffers against wildfire smoke, for instance, preventing large amounts of particulate pollution from reaching more densely populated areas nearby. A 2025 analysis identified Vale do Javari as one of Brazil’s most significant hot spots for future species discovery, meaning that habitat loss there could extinguish biodiversity that scientists have not even documented yet.

Those broader patterns align with what de Oliveira and his collaborators are observing on the ground and in satellite records. Their analysis showed that the forest interior of Vale do Javari remains relatively resistant to burning, but the surrounding landscape has changed markedly. In the 200-kilometer buffer zone, annual burned area has risen sharply in recent decades, with some of the highest values on record appearing in the past 2 years. “The signals are strongest at the edges,” de Oliveira said. “You see repeated fire in certain locations, and those are the places where degradation begins.”

To detect degradation that might not yet appear in traditional deforestation maps, the team also examined thermal anomalies from Landsat and Sentinel data. Deviations in surface temperature, de Oliveira said, can indicate canopy opening or drying under the trees. “A healthy, closed canopy regulates energy very efficiently,” he explained. “But when the canopy thins or fire has passed through multiple times, the ground heats up more. That thermal signature tells us something is happening below the leaves, even before clear-cutting takes place.”

The group validated some of these signals with fieldwork in regions just outside the Indigenous territory. They have not yet worked inside Vale do Javari itself.

The researchers found that small paths, recurring burn scars, and subtle canopy disruptions appear to align with known routes used for illegal logging, poaching, and other forms of encroachment. “It’s not the classic pattern of a large clear-cut,” said de Oliveira. “It’s a much slower, quieter process—fire escaping from pasture or burning the same patch of forest two or three times until it loses its resilience.”

Research as a Conservation Tool

“Repeated fire—especially combined with extreme drought—moves the system toward collapse.”

The gradual erosion of forest health is one of the team’s main concerns. “If a forest burns once, it can recover,” de Oliveira said. “But repeated fire—especially combined with extreme drought—moves the system toward collapse. You may not see deforestation immediately, but the structure and function of the forest are already changing.”

De Oliveira and his fellow researchers hope their maps will serve as a tool for early intervention, particularly in the buffer zones with the highest fire risk. The next step, de Oliveira said, is to work with local and federal agencies to establish targeted conservation strategies that extend beyond Indigenous land boundaries.

“Protection cannot stop at the line on a map,” he added. “We need buffer zone policies and monitoring systems that recognize how these landscapes are connected. Vale do Javari is still a stronghold, but the data show that what happens around it will determine its future.”

—Meghie Rodrigues (@meghier.bsky.social), Science Writer

Citation: Rodrigues, M. (2025), Fire encroaches on one of the Amazon’s most pristine Indigenous lands, Eos, 106, https://doi.org/10.1029/2025EO250467. Published on 15 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

As Earth’s population continues to grow and strain environmental resources, researchers are increasingly examining how humans might one day build settlements beyond Earth. Not many construction materials can withstand extreme temperatures and low-pressure environments like those that exist on Mars, however. New research explores an unconventional candidate: ice.

“This study…is expanding and questioning, How do we support life on other worlds?” said Rafid Quayum, a postbaccalaureate student at Harvard University and a researcher on the project. “Can we come up with a solution that’s environmentally friendly and also inspired by Earth’s systems?”

Ice, Quayum’s team says, offers a rare combination of benefits that can mitigate many of the environmental challenges astronauts would face: It absorbs radiation, transmits visible light, and can create a passive greenhouse effect inside enclosed habitats. That assumes, of course, that astronauts can harvest it.

Icy Habitats

Humans have been building temporary and permanent structures out of ice and snow for centuries. From the igloos and quinzhee of some Inuit peoples in Greenland and the Canadian Arctic to Kamakura in Japan, people have long recognized that ice can retain heat, keep out the elements, and be sourced in many cold environments.

But while ice retains its insulating qualities in environments beyond Earth, it may not be readily available, explained Armin Kleinboehl, a planetary scientist at the Jet Propulsion Laboratory in Pasadena, Calif., who was not involved in the study. Sourcing ice locally, especially on Mars, would be challenging. While Mars’s poles contain abundant ice, their harsh seasonal cycles make them unsuitable for long-term habitats, he said.

Unlike shelters built from regolith, ice domes would allow natural light to filter in, an advantage for both plant growth and human psychological well-being.

“If you were to build a build a habitat in those regions, you would want people to get out before the polar winter sets in,” Kleinboehl said. Instead, mission planners often target the northern midlatitudes, where shallow subsurface ice may be easier to access, he added.

Still, ice has certain advantages as a building material. Unlike shelters built from regolith, the fine layer of planetary topsoil made of dust, soil, and broken rock, ice domes would allow natural light to filter in, an advantage for both plant growth and human psychological well-being, Quayum said.

What’s more, even if surface ice isn’t easily accessible in the regions on Mars where humans might want to build, the resources are abundant on icy worlds like Ceres and Callisto, the researchers noted. Sourcing the ice from other planetary bodies could reduce the energy and cost of transporting materials from Earth.

Keeping Warm in Cold Environments

Quayum’s team modeled hypothetical ice domes that could be built on Mars’s surface, explored techniques to create them, and simulated what the conditions would be like inside. They placed their simulated domes at the midlatitudes of Mars, where ice is less accessible than at the poles but sunlight is more abundant. In these regions, daily temperatures swing from −56°C to −37°C, which is not enough to melt the ice, according to the model.

Removing dust and regolith allows the resulting ice shell to transmit sunlight while acting as radiation shielding.

In addition to temperature, Mars’s atmospheric pressure, which is less than 1% of Earth’s, also presented a challenge. Because liquid water cannot exist stably at such low pressures—it boils and freezes almost simultaneously—the team proposed using vacuum distillation to purify locally sourced ice. With this technique, heated ice vaporizes rather than melts. The vapor can then be captured, condensed into a liquid under high pressure, purified, and refrozen into clear, contaminant-free ice. Removing dust and regolith during this process allows the resulting ice shell to transmit sunlight while acting as radiation shielding, Quayum explained.

In the modeled ice domes, hydrophobic seals reinforced the dome by preventing any interior melted water from seeping into the shell, where it could weaken the ice. An aerogel insulating layer further slowed heat transfer to keep the outer layer below its melting point. Inside the habitat, sunlight warmed the air.

“There will be convection, like on Earth, to mix heat around, which should result in a fairly uniform temperature throughout [the dome],” said Robin Wordsworth, a planetary scientist at Harvard University and a researcher on the project.

The heat from that air then moved outward through the ice by conduction, a process that prevented the shell from losing strength. Temperature models and 3D structural simulations suggest the dome could remain stable at average Martian temperatures of roughly −58°C.

The team will present these results on 16 December at AGU’s Annual Meeting 2025 in New Orleans.

Testing Beyond Theory

The team said that a lot of research is still needed to determine whether ice domes could be a viable habitat for future Martian astronauts. Like Earth, Mars has seasonal variations that could affect the long-term durability of the domes, an effect they hope to investigate further.

To try to move Mars ice habitats beyond theory, the researchers aim to conduct field tests in extreme environments on Earth that mimic Martian conditions, such as the subzero temperatures of Antarctica and low-pressure environments like the Himalayas. If those are successful, structural habitability could eventually be tested on Mars itself.

“It would be something really exciting for scientists to be able to travel to other planetary environments, conduct field work, and be able to stay in habitats…using ice,” said Quayum.

—Olivia Maule (@ocmaule), Science Writer

Citation: Maule, O. (2025), Could future Mars habitats be made of ice?, Eos, 106, https://doi.org/10.1029/2025EO250456. Published on 15 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Taking the train or subway can be a time and cost-efficient way for city dwellers to commute. But during the summer months, some metro riders risk exposure to extreme heat, the deadliest weather-related hazard in the United States, while walking to and from stations.

A team of researchers at George Mason University in Fairfax, Va., analyzed the surface temperatures of walkways within a 10-minute walk of the three U.S. metro systems with the largest ridership. Then, they considered how socioeconomic factors, such as age and race, and development patterns, such as parking lots and indoor walkways, were related to differing levels of heat exposure.

The project began out of curiosity, said Luis Ortiz, an urban climate scientist at George Mason University. “It combines two of my big passions,” he said. As a longtime urban heat researcher and avid public transit user, Ortiz sought to answer a question from his day-to-day life: “If you’re a pedestrian using public transportation, what does your heat exposure look like?”

Black, Asian, and Hispanic commuters experience higher exposure to extreme heat.

The scientists combined station ridership data and Landsat 8 estimates of surface temperature to map where pedestrian public transit users were most exposed to heat on the New York City Subway, the Washington Metro, and the Chicago “L.” Ortiz will present the results on 16 December at AGU’s Annual Meeting 2025 in New Orleans.

The researchers found that the correlation between socioeconomic and demographic variables and surface temperatures were highest for the Chicago L and lowest for the Washington Metro. One pattern the researchers observed across all three cities is that commuters with minoritized identities, including Black, Asian, and Hispanic commuters, experience higher exposure to extreme heat, said coauthor Alireza Ermagun, a transportation scientist. So, too, do elderly populations and metro users between age 25 and 44.

Researchers analyzed the surface temperatures within a 10-minute walk of a metro station in three U.S. cities. Credit: Luis Ortiz, George Mason University

One result from the Washington Metro system seemed to contradict these correlations: Some of the hottest stations are in relatively wealthy areas of northern Virginia. Researchers attribute the unexpected finding to people driving to metro stations and parking a car. “They have massive parking lots there that get very hot in the afternoon,” Ortiz said.

A Green Solution

Urban planners should use research like this to strategize where to put shade and green space, said Nadav Sprague, an environmental epidemiologist at Harvard University who was not involved in the study. “Having access to shade is very important,” he said.

Many of the walking routes with high heat exposure have very few trees, Ortiz said. He said that trees “solve several of the issues” that cause heat stress by providing shade, reducing heat radiation into the body, and cooling the air.

“The best shade shelters are the trees.”

Transit users agree. “The best shade shelters are the trees,” said Jasper Elysian, a student at the University of Illinois Chicago who takes public transit to school, work, and almost everywhere. When it’s available, Elysian uses shade to combat the heat but said they would like to see more trees near transit stops.

Quantifying heat exposure to understand who is exposed and how is important, Sprague said, because it’s a hyperlocal problem requiring localized solutions. This research “gets at the point that each…place [faces] different implications of climate change.”

To better understand each city’s specific challenges, Ortiz and Ermagun said they want to collect more data on how often people in these cities in different socioeconomic situations use public transit and whether this usage is affected by the heat exposure they endure.

Recognizing that cities and counties have limited budgets, Ermagun hopes the team’s analysis will help decisionmakers identify where funds can be most useful in mitigating climate vulnerability. The ideal audience for this work, he said, is transportation designers.

—Pepper St. Clair (@pepperstclair.bsky.social), Science Writer

Citation: St. Clair, P. (2025), City dwellers face unequal heat exposure en route to the metro, Eos, 106, https://doi.org/10.1029/2025EO250461. Published on 15 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

In the last few days on November 2025, Cyclone Senyar brought torrential rainfall to parts of Indonesia, and in particular to Sumatra. At the time or writing, at least 1,022 people are known to have been killed and 206 more are missing.

One area that has been particularly badly impacted is Malalak, which is located in Agam Regency in West Sumatra – at [-0.39384, 100.27425]. This is a Google Earth image of the town, collected in February 2025:-

Google Earth image of Malalak in Indonesia, collected in February 2025.

Note the presence of the volcanoes close to the town, and the deeply incised river channels. This is a location at risk from channelised debris flows.

Unfortunately, this is a cloudy place, so obtaining good imagery is hard. But on 1 December 2025, Planet Labs captured an image using their PlanetScope sensors that give a sense of what has happened. This is the image:-

Satellite image of Malalak in Indonesia, in the aftermath of the catastrophic debris flows. Image copyright Planet Labs, used with permission, collected on 1 December 2025.

The sources of the landslides in the images remain hidden. However, it is evident is five substantial channelised debris flows that have affected the area, many of which have multiple upstream sources. There are some smaller events too. There is a high level of destruction as many of these landslides have flowed through the urban areas.

Reuters has a gallery of images of the aftermath of the landslides at Malalak, and there is some footage of the aftermath of the events too:-

Hopefully, imagery will become available that gives a sense of the source of these failures. In my mind, to be in a town with multiple channelised debris flows from different directions is hellish. This scenario appears to have occurred in several locations in Indonesia at the end of November.

Acknowledgement

Thanks as always to Planet Labs (2025) for their amazing imagery.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

In Alaska, winter is more than a season—it is survival. For Indigenous communities in Aniak, St. Mary’s, and Elim, snow and frozen rivers guide travel, hunting, and fishing. But those conditions are becoming less reliable in the Arctic, the fastest-warming region on Earth.

“The spring and the fall seasons are crunching in on the time frame where there’s enough snow and safe conditions to be able to move around,” said Helen Cold, a subsistence resource specialist with the Alaska Department of Fish and Game.

Indigenous communities “know their river better than anyone else in the world.”

With the Arctic Rivers Project, scientists and community leaders are racing to track changes in Alaska’s winters and plan for the future. By combining Indigenous Knowledges with high-resolution climate models, a team is working to build a collection of “storylines” to capture winter shifts and serve as tools for adaptation.

“There’s been a big movement in climate science to use narrative approaches to describe impacts,” said University of Colorado Boulder hydrologist Keith Musselman, who will present the research with his team on 15 December at AGU’s Annual Meeting 2025 in New Orleans. After all, Indigenous communities “know their river better than anyone else in the world.”

Voices from the River

Musselman and his colead, Andrew Newman, a hydrometeorologist at the National Science Foundation’s National Center for Atmospheric Research, leaned on local leadership by creating an Indigenous Advisory Council of 10 regional representatives. The council shaped research questions and ensured Indigenous Knowledges guided methods, data, and interpretation throughout the project.

To understand initial concerns, the research team convened the 2022 Arctic Rivers Summit to hear directly from community members. During the summit, council members emphasized the importance of inclusive planning to address climate change in ways that safeguard both people and ecosystems. In conjunction with the summit, interviews and workshops captured observations of shorter winters, thinner snowpack, midwinter thaws, and hazardous river ice. One respected elder and 15-time Iditarod racer shared that in his lifetime, he has witnessed more intense snowfall events and reduced snow persistence. Some communities also voiced concerns about more frequent coastal storms and shifts in wildfire patterns driven by lightning during dry periods.

Indigenous Knowledge holders shared their knowledge during a participatory mapping workshop in Kotlik, Alaska, as part of the Arctic Rivers Project. Credit: Nicole M. Herman-Mercer, USGS

Such shifts have major consequences, including reduced food security for Indigenous people who rely heavily on the land. Michael Williams, an Aniak tribal advocate and Indigenous Advisory Council member, said these climatic changes “make our hunting practices very dangerous.” Over the past 20 to 40 years, he has observed extreme temperatures in the area and a nearly 50% reduction in ice thickness on nearby rivers—changes that make traveling and hunting mammals, migratory birds, and fish a serious challenge.

“It has changed everything here,” Williams said. “It’s affecting our ways of life.”

Bridging River Wisdom and Climate Data

Researchers compared community observations with data from historical records, satellite measurements, and U.S. Geological Survey sensors to recreate past conditions and generate six climate scenarios for Alaska’s winters from 2035 to 2065. Beyond standard climate indicators like air temperature, the chain of models simulated hydroclimatic patterns such as streamflow, snowmelt timing, river ice dynamics, and fish population conditions.

Records corroborated what communities had observed for years, and the models indicated even harsher changes could be ahead, although northern regions could see increased snowpack as winter precipitation rises. Translating these results into usable guidance requires careful planning. Communities were both concerned and curious when shown initial results, asking to compare conditions across regions to understand what their neighbors were experiencing.

“If we don’t include [Indigenous voices], then we’re dead. We’re good as dead.”

The initial phase of the project, which involved gathering and analyzing information, ended in 2024. But to support effective, accessible communication, the team will continue codeveloping “narratives of change” that weave together datasets, Indigenous Knowledges, and lived experience. They’re also exploring how tools like maps and Facebook channels can help share science with affected communities, with the goal of supporting intuitive, locally led adaptation as climate change reshapes life in Alaska.

Past adaptation strategies have often fallen short in including Native realities, said Cold, who was not involved in the research. She thinks the Arctic Rivers Project’s approach is a step in the right direction toward more inclusive climate planning.

Community leaders echo that sentiment and emphasize the urgency of such efforts. “Mitigation planning has to be ongoing in our communities for the survival of our people,” Williams said. “If we don’t include [Indigenous voices], then we’re dead. We’re good as dead.”

—Cassidy Beach, Science Writer

Citation: Beach, C. (2025), Changing winters leave Indigenous Alaskans on thin ice, Eos, 106, https://doi.org/10.1029/2025EO250466. Published on 12 December 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.