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Coastal waters worldwide are rapidly losing oxygen, causing declines in marine life and affecting communities who rely on the health of coastal waters.

Prominent examples of low-oxygen coastal waters are found in the Baltic Sea, for instance, where oxygen loss in recent decades has led to major ecosystem changes. Potentially toxic cyanobacterial blooms have become frequent and widespread, spawning grounds for cod have been greatly reduced, and fish kills have been observed in coastal waters [Conley et al., 2009]. Similar issues have afflicted the Gulf of Mexico, the Adriatic Sea, the East China Sea, and numerous other areas.

Dead fish are seen in coastal waters near Ostend, Belgium, following a low-oxygen event in 2018. Credit: Grégoire et al. [2023], European Marine Board, CC BY 4.0

The main cause of declining coastal ocean oxygen is well-known: Since the 1950s, phosphorus and nitrogen from agricultural runoff and wastewater have flowed into coastal seas, where they stimulate phytoplankton blooms that, upon their decay, consume oxygen. This process, called eutrophication, is not the only cause of declining oxygen and so-called dead zones in coastal waters: Increasing global temperatures are contributing by reducing both the solubility of oxygen in seawater and vertical mixing of the ocean water column, thereby limiting the aeration of deeper waters [Breitburg et al., 2018].

Indeed, even coastal systems not experiencing eutrophication, such as the Gulf of St. Lawrence in Canada, may be under threat of low oxygen because of changes in ocean circulation linked to climate change [Wallace et al., 2023].

Various means of artificial reoxygenation have been suggested and studied as possible local to regional solutions to coastal oxygen loss.

Long-term reductions in nutrient inputs from land are widely acknowledged as essential to mitigate coastal eutrophication, but such reductions will take time to have an effect. Nutrients have been accumulating in many coastal systems for decades, and switching off inputs will not immediately lead to lower concentrations [Conley et al., 2009]. Moreover, reducing nutrient releases from agricultural lands in many regions is proving challenging. Attempts to curtail the global use of fossil fuels and cut greenhouse gas emissions substantially have also been less successful to date than what is required to affect ocean oxygen [Breitburg et al., 2018].

Amid the challenges of achieving global-scale solutions, various means of artificial reoxygenation have been suggested and studied as possible local to regional solutions to coastal oxygen loss [Stigebrandt et al., 2015]. Yet these approaches come with risks that must be assessed carefully before implementation [Conley et al., 2009].

Such assessments are becoming urgent with the emergence of potential new artificial reoxygenation technologies linked to green hydrogen production. This process of splitting water by electrolysis to generate hydrogen also generates oxygen [Wallace et al., 2023], which could be put to use in coastal waters, particularly where green hydrogen production facilities are located close to the sea.

Oxygen Supply Versus Demand

Coastal seas gain oxygen naturally through air-sea exchange, vertical and lateral mixing of seawater, and photosynthetic production by phytoplankton (Figure 1). They lose oxygen through respiration of organic matter in the water column and the underlying sediment. Surface waters typically remain oxygenated because of rapid air-sea exchange and primary productivity, but in deeper waters, oxygen removal may dominate, especially in systems with limited vertical mixing [Fennel and Testa, 2019].

Fig. 1. The oxygen budget for coastal ocean systems involves several main processes.

The main goal of artificial reoxygenation is to increase the supply of oxygen to deeper waters enough that the water and sediment at the seafloor surface become or remain oxygenated. The oxygen supply needed to achieve this goal depends on the local oxygen demand, which itself depends on the input of organic matter from sinking phytoplankton biomass and the eutrophication history of the system. If organic matter inputs remain high or a lot of organic matter has accumulated on the seafloor, oxygen demand may remain high for a long time. This “legacy” effect can hinder the reoxygenation of a coastal system, as shown in the Baltic Sea [Hermans et al., 2019].

A secondary goal of reoxygenation is to limit recycling of phosphorus from sediments, which, in turn, may reduce the availability of phosphorus as a nutrient for phytoplankton in surface waters. Decreasing how much organic matter is produced and then sinks to the seafloor may lower the oxygen demand for respiration and hence increase oxygen concentrations in deeper waters [Conley et al., 2009].

Inspired by methods used to reoxygenate lakes with some success, two broad approaches have been proposed for artificially reoxygenating coastal systems (Figure 2): bubbling pure oxygen or air into the ocean [Koweek et al., 2020; Wallace et al., 2023] and pumping oxygenated surface water to greater water depths, a process called artificial downwelling [Stigebrandt et al., 2015; Lehtoranta et al., 2022].

Fig. 2. Two key methods for artificially reoxygenating coastal waters include bubble diffusion (left) and downwelling (right). O2, oxygen. Credit: Adapted from Koweek et al. [2020], CC BY 4.0

Bubble diffusers have been used in lakes to oxygenate deep water directly [Koweek et al., 2020] and in shallow coastal systems to destratify and aerate the water column by inducing mixing [Harris et al., 2015]. Artificial downwelling has been tested for local applications in only a few small coastal systems [Stigebrandt et al., 2015; Lehtoranta et al., 2022].

The Imperfections of Artificial Reoxygenation

Studies to date show that artificial reoxygenation can be applied successfully in small estuaries and bays but that its effect lasts only as long as operations are maintained.

Studies to date show that artificial reoxygenation can be applied successfully in small estuaries and bays but that its effect lasts only as long as operations are maintained. This outcome was observed, for example, in two Swedish bays following their reoxygenation through pump-driven downwelling [Stigebrandt et al., 2015; Lehtoranta et al., 2022]. Similarly, when aerators were switched off in a shallow subestuary of the Chesapeake Bay after several decades of aeration, low-oxygen, or anoxic, levels returned within a day [Harris et al., 2015].

The rapid return of anoxia upon discontinuing artificial reoxygenation operations—also known from applications in lakes—illustrates that these approaches alone do not provide permanent solutions to deoxygenation because they do not address its root causes. Moreover, adding oxygen to the water column does not mitigate wider water quality problems. Nuisance algal blooms in many coastal areas will still occur if the availability of nutrients for phytoplankton remains high.

In the Baltic Sea, for example, natural decadal-scale reoxygenation of deeper waters linked to lateral inflow of oxygenated North Sea water does not lead to a removal of phosphorus in the sediment [Hermans et al., 2019]. This lack of an effect results from the highly reducing conditions in the seafloor sediment, which hinder formation of phosphorus-containing minerals. Consequently, reoxygenation of the water column in the Baltic does not necessarily decrease recycling of phosphorus [Hermans et al., 2019], which may continue to fuel cyanobacterial blooms [Conley et al., 2009].

Reoxygenation via artificial downwelling may also be unsuccessful if it causes warming of deeper waters, which is a risk, especially when surface water pumps are used to reoxygenate temperature- and density-stratified coastal waters. Transferring warm surface water to colder, denser depths near the seafloor may weaken stratification and enhance vertical mixing. Although this process may increase the downward transfer of oxygen, it can also boost upward mixing of nutrients, which may enhance biological productivity. This enhancement can ultimately increase the oxygen demand in deeper waters to such an extent that a net decrease in oxygen results [Conley et al., 2009; Lehtoranta et al., 2022].

Warming at depth can also lead to greater metabolic activity and increased respiration of organic matter, further decreasing oxygen concentrations instead of increasing them as intended.

Side Effects on Climate and Habitats

Artificial reoxygenation may have other undesirable effects as well. It can alter the dynamics of greenhouse gases in coastal waters, for example, because increased aerobic respiration increases carbon dioxide production.

Furthermore, bubbling air through shallow coastal waters can enhance upward transport of methane, a potent greenhouse gas, in the water column and its emission to the atmosphere [Lapham et al., 2022]. In eutrophic coastal systems, reoxygenation does not necessarily suppress the release of methane from sediments [Żygadłowska et al., 2024], implying that upon bubbling, methane emissions from coastal waters may be greater than without reoxygenation.

Reoxygenation operations may also alter ocean habitats and have unintended consequences for marine life. Bubbling generates underwater noise, turbulence, and gradients in oxygen pressure that differ from naturally occurring conditions. Artificial downwelling not only changes water column temperatures but also alters vertical salinity distributions, with unknown consequences for marine organisms [Conley et al., 2009; Wallace et al., 2023]. In addition, the return of bottom-dwelling animals with reoxygenation may cause increased sediment mixing that remobilizes sediment contaminants [Conley et al., 2009].

Assessing Artificial Reoxygenation as a Solution

Artificial reoxygenation, when applied, should always be only one of various measures used to improve water quality.

Taken together, the body of evidence from reoxygenation studies to date indicates that long-term improvements in the oxygen levels and quality of coastal waters require reductions in nutrient inputs and greenhouse gas emissions. Hence, artificial reoxygenation, when applied, should always be only one of various measures used to improve water quality.

In heavily managed coastal systems, reoxygenation may be a temporary solution, as illustrated by its successful application in a subestuary of the Chesapeake Bay [Harris et al., 2015]. Elsewhere, such as in the Gulf of St. Lawrence, reoxygenation might be harnessed to maintain the current oxygen state of the system [Wallace et al., 2023]. However, responses to reoxygenation in eutrophic systems with strong legacy effects, where sediments act as a source of nutrients and a sink for oxygen, are very difficult to predict [Conley et al., 2009; Hermans et al., 2019].

The dependence of reoxygenation effects, either from aeration or from pumping, on site-specific biological, chemical, and physical characteristics, which are often poorly known and differ greatly worldwide, also hinders predictions of responses. Yet accurately predicting the effects of artificial reoxygenation before implementing it is critical and consistent with the precautionary principle that in the absence of scientific certainty, we should act to avoid harm.

This principle can be interpreted to suggest that no measures should be taken in some cases and that in other cases, measures should not be postponed because delay could lead to even more harm. Thus, careful case-by-case assessments of the suitability of artificial reoxygenation at given sites are needed—as is careful monitoring when operations are implemented. Modeling studies are valuable for such assessments [e.g., Koweek et al., 2020] but must be paired and validated with field data.

The potential availability of substantial oxygen supplies to support artificial reoxygenation as a result of increasing green hydrogen production further raises the urgency of suitability assessments [Wallace et al., 2023]. If such supplies can be tapped near coastal areas, they may help make artificial aeration operations logistically more viable and sustainable.

Foundations for Responsible Reoxygenation

For areas found to be potentially well suited for artificial reoxygenation interventions, consensus best practices should be followed when initiating pilot studies or larger implementations. As informed by discussions during a recent meeting organized by the United Nations Educational, Scientific and Cultural Organization Intergovernmental Oceanographic Commission’s Global Ocean Oxygen Network, several elements are foundational to these best practices.

Relevant government bodies, such as national and local water management authorities; stakeholders, including representatives of local communities; and scientists should be involved from the outset to safeguard the interests of all parties. Field trials and implementations should consider perceived environmental benefits and risks of the intended intervention, as well as relevant ethical issues, taking into account the intrinsic value of nature.

Monitoring is important for understanding baseline conditions and assessing the effects of reoxygenation on water quality and ecology, including termination effects after an intervention ceases.

Key biological, chemical, and physical parameters of the system where the intervention will occur (as well as of a reference site) should be monitored before, during, and afterward. This monitoring is important for understanding baseline conditions and assessing the effects of reoxygenation on water quality and ecology, including termination effects after an intervention ceases. Continued measurements over years to decades are also critical to determine longer-term effects.

Finally, the results of all field trials, including failures, should be reported completely, transparently, and publicly.

Artificial reoxygenation is unlikely to be a permanent solution to declining ocean oxygen, and it cannot replace essential measures to reduce greenhouse gas emissions and nutrient inputs to ocean waters. But with science-based suitability assessments and ethical, environmentally safe practices, reoxygenation interventions might prove beneficial in some places, allowing temporary mitigation of the detrimental consequences of coastal deoxygenation.

Acknowledgments

This feature article summarizes the discussion of a workshop on marine reoxygenation organized by the Global Ocean Oxygen Network (GO2NE) on 10–11 September 2024. We thank all participants for their contributions: D. Austin, L. Bach, L. Bopp, D. Breitburg, A. Canning, D. Conley, M. Dai, B. DeWitte, H. Enevoldsen, E. Ferrar, A. Galan, V. Garcon, M. Gregoire, B. Gustafsson,, D. Gutierrez, A. Hylén, K. Isensee, R. Lamond, M. Li, K. Limburg, I. Montes, J. Sterling, A. Tan Shau Hwai, J. Testa, D. Wallace, J. Waniek, and M. Yasuhara.

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Breitburg, D., et al. (2018), Declining oxygen in the global ocean and coastal waters, Science, 359, 1–13, https://doi.org/10.1126/science.aam7240.

Conley, D. J., et al. (2009), Tackling hypoxia in the Baltic Sea: Is engineering a solution?, Environ. Sci. Technol., 43, 3,407–3,411, https://doi.org/10.1021/es8027633.

Fennel, K., and J. M. Testa (2019), Biogeochemical controls on coastal hypoxia, Annu. Rev. Mar. Sci., 11, 105–130, https://doi.org/10.1146/annurev-marine-010318-095138.

Grégoire, M., et al. (2023), Ocean Oxygen: The Role of the Ocean in the Oxygen We Breathe and the Threat of Deoxygenation, edited by A. Rodriguez Perez et al., Future Sci. Brief 10, Eur. Mar. Board, Ostend, Belgium, https://doi.org/10.5281/zenodo.7941157.

Harris, L. A., et al. (2015), Optimizing recovery of eutrophic estuaries: Impact of destratification and re-aeration on nutrient and dissolved oxygen dynamics, Ecol. Eng., 75, 470–483, https://doi.org/10.1016/j.ecoleng.2014.11.028.

Hermans, M., et al. (2019), Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin, Geochim. Cosmochim. Acta, 246, 174–196, https://doi.org/10.1016/j.gca.2018.11.033.

Koweek, D. A., et al. (2020), Evaluating hypoxia alleviation through induced downwelling, Sci. Total Environ., 719, 137334, https://doi.org/10.1016/j.scitotenv.2020.137334.

Lapham L. L., et al. (2022), The effects of engineered aeration on atmospheric methane flux from a Chesapeake Bay tidal tributary, Front. Environ. Sci., 10, 866152, https://doi.org/10.3389/fenvs.2022.866152.

Lehtoranta, J., et al. (2022), Different responses to artificial ventilation in two stratified coastal basins, Ecol. Eng., 179, 106611, https://doi.org/10.1016/j.ecoleng.2022.106611.

Stigebrandt, A., et al. (2015), An experiment with forced oxygenation of the deepwater of the anoxic By Fjord, western Sweden, Ambio, 44(1), 42–54, https://doi.org/10.1007/s13280-014-0524-9.

Wallace, D., et al. (2023), Can green hydrogen production be used to mitigate ocean deoxygenation? A scenario from the Gulf of St. Lawrence, Mitigation Adapt. Strategies Global Change, 28, 56, https://doi.org/10.1007/s11027-023-10094-1.

Żygadłowska, O. M., et al. (2024), Eutrophication and deoxygenation drive high methane emissions from a brackish coastal system, Environ. Sci. Technol., 58, 10,582–10,590, https://doi.org/10.1021/acs.est.4c00702.

Author Information

Caroline P. Slomp (caroline.slomp@ru.nl), Radboud University, Nijmegen, Netherlands; also at Utrecht University, Netherlands; and Andreas Oschlies, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany

Citation: Slomp, C. P., and A. Oschlies (2025), Could bubbling oxygen revitalize dying coastal seas?, Eos, 106, https://doi.org/10.1029/2025EO250163. Published on 1 May 2025. Text © 2025. The authors. CC BY 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

As droughts worsen and water shortages hit communities worldwide, a new study in the journal Decision Analysis has uncovered a smarter way to get people to save water—without breaking the bank.

SummaryThe development of reliable operational earthquake forecasts is dependent upon managing uncertainty and bias in the parameter estimations obtained from models like the Epidemic-Type Aftershock Sequence (ETAS) model. Given the intrinsic complexity of the ETAS model, this paper is motivated by the questions: “What constitutes a representative sample for fitting the ETAS model?” and “What biases should we be aware of during survey design?”. In this regard, our primary focus is on enhancing the ETAS model’s performance when dealing with short-term temporally transient incompleteness, a common phenomenon observed within early aftershock sequences due to waveform overlaps following significant earthquakes. We introduce a methodological modification to the inversion algorithm of the ETAS model, enabling the model to effectively operate on incomplete data and produce accurate estimates of the ETAS parameters. We build on a Bayesian approach known as inlabru, which is based on the Integrated Nested Laplace Approximation (INLA) method. This approach provides posterior distributions of model parameters instead of point estimates, thereby incorporating uncertainties. Through a series of synthetic experiments, we compare the performance of our modified version of the ETAS model with the original (standard) version when applied to incomplete datasets. We demonstrate that the modified ETAS model effectively retrieves posterior distributions across a wide range of mainshock magnitudes and can adapt to various forms of data incompleteness, whereas the original model exhibits bias. In order to put the scale of bias into context, we compare and contrast further biases arising from different scenarios using simulated datasets. We consider: (1) sensitivity analysis of the modified ETAS model to a time binning strategy; (2) the impact of including and conditioning on the historic run-in period; (3) the impact of combination of magnitudes and trade-off between the two productivity parameters K and α; and (4) the sensitivity to incompleteness parameter choices. Finally, we explore the utility of our modified approach on three real earthquake sequences including the 2016 Amatrice earthquake in Italy, the 2017 Kermanshah earthquake in Iran, and the 2019 Ridgecrest earthquake in the US. The outcomes suggest a significant reduction in biases, underlining a marked improvement in parameter estimation accuracy for the modified ETAS model, substantiating its potential as a robust tool in seismicity analysis.

Historic wildfires broke out in South Korea in late March 2025, killing 32 people, injuring 45, and displacing about 37,000. In total, the fires burned more than 100,000 hectares (about 247,000 acres), nearly quadruple the area that burned in the country’s previous worst recorded fire season in 2000. (In comparison, the January 2025 Palisades and Eaton Fires in Southern California burned about 91,000 hectares, or 37,000 acres.)

“This study adds to a growing body of science showing how climate change is making weather conditions more favorable to dangerous wildfires.”

A new study by scientists with World Weather Attribution (WWA) suggests that atmospheric warming—caused primarily by fossil fuel burning—made the hot, dry, and windy conditions that drove the South Korean fires about twice as likely and 15% more intense.

About 5,000 buildings burned, including homes, industrial structures, farms, and cultural heritage sites such as the Gounsa Temple in Uiseong, which was originally built in 618 CE.

Credit: World Weather Attribution

“The scale and speed of the fires were unlike anything we’ve ever experienced in South Korea,” said June-Yi Lee, an atmospheric scientist at Pusan National University and the Institute for Basic Science, in a statement. “This study adds to a growing body of science showing how climate change is making weather conditions more favorable to dangerous wildfires.”

Hot, Dry, and Windy

WWA researchers examined the Hot-Dry-Windy Index (HDWI) across the entire country for the month of March. This metric calculates fire risk from temperature, humidity, and wind speed observations.

The combination of high temperatures, low humidity, and high wind speeds that occurred from 22 to 26 March were unusual, even for today’s climate, the researchers found. Such conditions are expected to occur in March only once every 340 years. But this combination of conditions would have been even rarer in a preindustrial climate, occurring only once every 744 years.

The study suggests that the trend in the HDWI was driven primarily by unseasonably high temperatures.

“From March 22–26, the daily maximum average temperature in southeastern Korea averaged around 25°C, which was 10°C higher than the normal March average,” Lee said in a press briefing. Little rain fell in the region this winter, which, combined with high temperatures, led to drier, more flammable fuels. Relative humidity was around 20% at the time of the fires, not unusual for March. Wind speeds on 25 March reached up to 25 meters per second, a short-lived spike that helped the fires spread quickly.

The WWA team also calculated that if the climate warms by another 1.3°C by 2100, the HDWI will continue to increase, with the conditions behind such fires growing another 2 times as likely.

The nature of WWA’s rapid response studies means they are not peer reviewed, but they have published peer-reviewed studies on the methodology they use in all of their analyses. The study marks the World Weather Attribution’s 100th rapid analysis since the organization formed in 2014. It is the sixth to focus on a wildfire.

Credit: World Weather Attribution A Strong Case

ClimaMeter, another project that examines how extreme weather events may have been affected by a changing climate, released a study about South Korea’s wildfires on 25 March. (As with the WWA study, it was not peer reviewed but used peer-reviewed methods.)

ClimaMeter uses a different methodology than WWA does but had similar findings, reporting that the meteorological conditions leading up to the fires were about 2°C hotter, 30% drier, and 10% windier compared with similar past events.

“For the moment, it’s more difficult to prove that climate change did not affect an event.”

Davide Faranda, a physicist with the French National Centre for Scientific Research and coordinator of ClimaMeter, pointed out that their study showed climate change strengthened the meteorological conditions conducive to fires, not necessarily that climate change caused the fires. He was not involved with the WWA study but noted that the two groups’ rapid response studies often arrive at similar or complementary findings.

“For the moment, it’s more difficult to prove that climate change did not affect an event,” he said.

“A decade ago, the influence of climate change on events was less clear. But now it’s undeniable. The wildfires in South Korea are a case in point,” said Friederike Otto, WWA colead and a climatologist at Imperial College London, in a statement.

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

Citation: Dieckman, E. (2025), Climate change heightened conditions of South Korean fires, Eos, 106, https://doi.org/10.1029/2025EO250170. Published on 30 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Geologists led by the University of Maryland and the University of Hawaiʻi finally connected the dots between one of the largest volcanic eruptions in Earth's history and its source deep beneath the Pacific Ocean.

Hundreds of millions of people live in areas that could be affected by volcanic eruptions. Fortunately, clues at the surface, such as earthquakes and ground deformation, can indicate movement within underground magma dikes—sheets of magma that cut across layers of rock. Scientists can use these clues to make potentially lifesaving predictions of eruptions.

Volcanoes erupting underwater have a distinctive effect on the climate that is larger and more widespread than previously thought, according to an international group led by University of Auckland and Tongan scientists. Research on Tonga's devastating 2022 Hunga eruption has just been published in the journal Nature Geoscience.

A new study led by Prof. Li Zhi from the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences has revealed a troubling global increase in snow droughts under different climate scenarios. The findings were recently published in Geophysical Research Letters.

Source: Community Science

Research shows that communities are best able to mitigate the effects of climate change when they can work alongside scientists on adaptation plans. Hanson et al. recently extended this finding to Indigenous communities in the Colorado Plateau, including members of the Navajo Nation, Hopi Tribe, and Ute Mountain Ute Tribe.

To learn more about the qualities that make climate education most accessible to these groups, the researchers conducted a series of listening circles, interviews, and consultations with Indigenous peoples and Westerners with extensive experience working in Indigenous communities. They collaborated with members of the Nature Conservancy’s Native American Tribes Upholding Restoration and Education, or NATURE, program, which aims to equip Indigenous college students with natural resource management skills.

Several themes emerged. Indigenous students are most likely to engage in climate education when they’re actively recruited for a program, when mentors are willing to learn from students as well as teach them, and when a program emphasizes the value of integrating Traditional Knowledges with Western science, for instance. Small class sizes and ample one-on-one instruction also keep students engaged.

On the basis of these findings, the researchers created a climate module that can be taught as part of a broader college-level environmental science curriculum, for example, as part of a program like NATURE. The module is “menu style,” meaning that instructors and students can choose the activities they find appealing from an array of options. One option is classroom lessons on issues that are relevant to the Colorado Plateau, such as water conservation and cattle management. Another involves field trips, such as a day trip down the Colorado River, during which guides provide insights into how climate change is altering the landscape.

Indigenous students are “uniquely positioned to engage in environmental restoration” because they have deep connections with natural systems, the researchers wrote. This collaboratively designed program could help students achieve this potential, they say. (Community Science, https://doi.org/10.1029/2023CSJ000054, 2025)

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

Citation: Sidik, S. M. (2025), Teaming up to tailor climate education for Indigenous communities, Eos, 106, https://doi.org/10.1029/2025EO250166. Published on 30 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: AGU Advances

Hundreds of millions of people live in areas that could be affected by volcanic eruptions. Fortunately, clues at the surface, such as earthquakes and ground deformation, can indicate movement within underground magma dikes—sheets of magma that cut across layers of rock. Scientists can use these clues to make potentially lifesaving predictions of eruptions.

But there is room for improvement. Eruption predictions rely on modeling magma dikes, and most models treat magma as a simple Newtonian fluid (like water) whose viscosity stays constant under stress. However, magma’s crystals and bubbles make it more likely to behave as a non-Newtonian fluid whose viscosity decreases under greater stress (known as shear thinning). That’s especially true as it approaches the surface. Ketchup behaves similarly: It pours more easily from a jar when shaken.

Lab experiments by Kavanagh et al. reveal new insights into the potential dynamics of non-Newtonian magma flow in dikes. These findings could ultimately help improve eruption prediction strategies.

To mimic magma dikes, the researchers injected various fluids into a translucent and elastic solid gelatin material representing Earth’s crust. The injected fluids contained suspended tracer particles that could be illuminated by laser light, allowing the researchers to track each fluid’s flow within the forming dike as it traveled up from the injection site to the surface, where it “erupted” from the gelatin. They compared the behaviors of two non-Newtonian shear-thinning fluids, hydroxyethyl cellulose (a thickener often found in cosmetics) and xanthan gum (a thickener often added to foods), to water, a Newtonian fluid.

The experiments showed that the flow patterns of these fluids were very different from the flow patterns of water. However, even though their internal flow patterns differed, all fluids formed dikes with a similar shape and speed as they approached the surface.

These findings suggest that the primary information currently used to predict impending eruptions—such as the shape and speed of magma dikes—does not necessarily correlate with information about magma flow dynamics within the dikes. This result is significant because flow dynamics depend on magma characteristics that can affect how explosive an eruption will be or how quickly or how far the lava will travel.

Further research could help link these findings to real-world geological evidence and explore how they might help to improve eruption forecasting, the researchers say. (AGU Advances, https://doi.org/10.1029/2024AV001495, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Matching magma dikes may have different flow patterns, Eos, 106, https://doi.org/10.1029/2025EO250167. Published on 30 April 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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

Supercritical fluids—hydrous silicate liquids where water and melt become fully miscible—are believed to play a key role in chemical transport and element redistribution in subduction zones. However, the atomic-scale processes underlying their high mobility are poorly understood.

Chen et al. [2025] use first-principle molecular dynamics simulations to examine the diopside–H2O system over a wide range of water contents, pressures (up to 12 gigapascals), and temperature (3000 kelvin). Their results show that water promotes the breakdown of the silicate network by converting bridging oxygens (BOs) into non-bridging oxygens (NBOs), leading to the formation of smaller, less polymerized silicate clusters with greater diffusivity and structural stability. This depolymerization enhances atomic mobility and reduces viscosity, with strong linear correlations observed between polymerization degree and transport properties. The findings identify water-induced depolymerization as the primary mechanism behind the high mobility of supercritical fluids.

These insights have broad implications for understanding magma transport dynamics and the geochemical signatures—such as uranium-thorium disequilibria—in arc lavas. The study highlights the critical role of water in regulating the structure and dynamics of silicate fluids in subduction-related magmatic and mineralizing processes.

Citation: Chen, B., Song, J., Zhang, Y., Wang, W., Zhao, Y., Wu, Z., & Wu, X. (2025). Water dissolution driving high mobility of diopside-H2O supercritical fluid. Journal of Geophysical Research: Solid Earth, 130, e2024JB030956.  https://doi.org/10.1029/2024JB030956  

—Jun Tsuchiya, Editor, JGR: Solid Earth

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.

About 240 miles long, Utah's Wasatch Fault stretches along the western edge of the Wasatch Mountains from southern Idaho to central Utah, running through Salt Lake City and the state's other population centers. It's a seismically active normal fault, which means it is a fracture in Earth's crust that has moved many times in the past.

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

I have frequently highlighted the growing impact of multiple landslide events triggered by extreme rainfall around the world. Whilst there is little doubt that such events are becoming more common, they have occurred through history too. I recently came across a paper (Fiorillo et al. 2019) that documented such an event in 1954. The account is fascinating.

The paper sought to use historic aerial images and topographic data to reconstruct an inventory of the landslide triggered during this event. The location is the area around the villages of Vietri sul Mare and Maiori, which are sited on the beautiful Amalfi Coast in the Campania region of southern Italy. This is the area in the vicinity of [40.67, 14.73] – the Google Earth image below shows the landscape as it is today:-

Google Earth image of the modern setting of the 1954 landslides on the Amalfi Coast in Italy.

The analysis of Fiorillo et al. (2019) indicates that in parts of this area, 500 mm of rainfall fell in the storm that triggered these landslides. They have mapped over 1,500 landslides triggered by the storm – these are shown in the map below:-

Landslides triggered during the 1954 rainfall event on the Amalfi Coast in Italy. Map by Fiorillo et al. (2019).

As the map shows, the density of landslides was extremely high in the hills above Vietri sul Mare and Maiori. The failures were mostly shallow landslides, with many transitioning into channelised debris flows.

In total, it is believed that 316 people lost their lives in this disaster. There is some archive footage of the aftermath in the Youtube video below:-

Reference

Fiorillo, F., Guerriero, L., Capobianco, L., Pagnozzi, M., Revellino, P., Russo, F., and Guadagno, F. M., 2019. Inventory of Vietri-Maiori landslides induced by the storm of October 1954 (southern Italy). Journal of Maps, 15 (2), 530–537. doi: https://doi.org/10.1080/17445647.2019.1626777

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SummaryThis study investigates the longitudinal (T1) to transverse (T2) relaxation time ratios in unconsolidated geological materials to determine how they vary across different geological units. Assessing the T1/T2 ratio can inform about the validity of the presumed relationship between T1 and T2 relaxation times in steady-state surface NMR modeling (i.e. T1/T2 ratio is assumed to be constant and equal to one). The T1/T2 ratio investigation is conducted by two-dimensional T1-T2 correlation data using laboratory and borehole NMR measurements at a Larmor frequency of 2 MHz and 430 kHz, respectively. Laboratory NMR measurements were performed on 73 sediment samples from 9 sites in Denmark and Germany, and borehole NMR measurements were conducted at 59 selected depth intervals in unconsolidated geological units across 8 sites in the same countries. Volumetric magnetic susceptibility of the laboratory samples was measured to evaluate the effects of magnetic susceptibility on the T1/T2 ratio. Our results indicate that the T1/T2 ratios in mineral soils and sediments are pretty similar for borehole NMR and lab NMR datasets, regardless of the geological unit. In these geological materials, the mean value of the T1/T2 ratios is 1.64 in lab-NMR and 1.82 in borehole NMR datasets. In contrast, in our in-situ borehole NMR measurements in organic peat soils, the mean value of the T1/T2 ratios was higher (i.e. 2.77), exhibiting a broader distribution ranging from 1 to 4.8. Moreover, we observed that magnetic susceptibility did not have a significant effect on the T1/T2 ratio in the investigated samples. More importantly, the findings in this study can be adopted in the modeling of steady-state surface NMR modeling routines where a constant ratio of 1 for T1/T2 is assumed when solving the Bloch equations. It is expected that updating the T1/T2 ratio can improve the accuracy of water content and relaxation time estimations derived from steady-state surface NMR measurements.

The ocean's deep-sea bed is scattered with ancient rocks, each about the size of a closed fist, called "polymetallic nodules." Elsewhere, along active and inactive hydrothermal vents and the deep ocean's ridges, volcanic arcs, and tectonic plate boundaries, and on the flanks of seamounts, lie other types of mineral-rich deposits containing high-demand minerals.

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The EPA plans to cancel 781 grants, almost all focused on environmental justice, according to a court document filed last week.

In Woonasquatucket River Watershed Council v. Department of Agriculture, a coalition of nonprofits is challenging the Trump administration’s freezing of funding from the Biden-era Inflation Reduction Act (IRA) and Bipartisan Infrastructure Law. In the recent court document, Daniel Coogan, an administrator in the Office of Mission Support for the EPA, stated that the agency completed a grant-by-grant review of its awards to ensure that grants aligned with administration priorities. Those that were not aligned were targeted for termination.

All 781 grants targeted for termination fall under programs formed by the IRA, a 2022 law that helped to promote clean energy and bolster environmental projects. Most of the grants are part of EPA programs focused on environmental justice and include projects to help some of the United States’ most environmentally disadvantaged communities be resilient to the effects of climate change and protect residents from pollution. 

According to the court document, 377 grantees have been notified that their funding has been terminated, and the remaining 404 grantees will receive notices within the next two weeks. 

Hundreds of grantees’ projects will be affected by the terminations. In one such project, San Diego nonprofit Casa Familiar expected to receive $12.7 million to help a majority-Latino community obtain low-cost, zero-emission transportation and indoor air monitors and purifiers. The group has been unable to withdraw funds for months and now awaits notification that their grant has been terminated. In another example, the community of Chiloquin, Oregon, now expects that a planned community center and disaster shelter may never be built after the EPA suspended funding for the project.

 
Related

•  EPA is Canceling Nearly 800 Environmental Justice Grants, Court Filing Reveals
•  Democrats Demand EPA Reverse Termination of Grants for Clean Air and Water
•  Court Filing From Daniel Coogan
• Get Involved: AGU Science Policy Action Center
 

The news of the cancellations comes shortly after hundreds of EPA employees working on diversity, equity, and inclusion and environmental justice issues were given notice that they would be fired or reassigned.

According to the Washington Post, experts are concerned that the EPA did not conduct the full grant-by-grant review process required to terminate ongoing grants. “They’re claiming to the court that each one of those was done on an individualized basis, even though they haven’t shown any evidence,” Jillian Blanchard, vice president of climate change and environmental justice at Lawyers for Good Government, told the Washington Post.

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

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Increasing the natural uptake of carbon dioxide by the ocean or storing captured CO₂ under the seabed are currently being discussed in Germany as potential ways to offset unavoidable residual emissions and achieve the country's goal of greenhouse gas neutrality by 2045.

The history of metal pollution in the city of São Paulo, the largest metropolis in Brazil and the Southern Hemisphere, can be read in the layers of sediment accumulated over the last century.

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In a joint statement yesterday, Mexican and U.S. officials announced that Mexico will immediately transfer some of its water reserves to the United States and also allow a larger share of the Rio Grande River to flow into the United States. This concession from Mexico, which will last through at least October, seems to have averted the threat of additional tariffs and sanctions threatened by President Trump in early April.

Mexico and the United States share several major rivers, including the Rio Grande, the Colorado, and the Tijuana. Control over how much water each country receives from these rivers was set in a 1944 treaty. Under the treaty, Mexico must deliver 1.75 million acre-feet of water to the United States from six tributaries every 5 years, or an average of 350,000 acre-feet every year (An acre-foot is the amount of water needed to cover 1 acre of land to a depth of 1 foot.)

 
Related

•  Mexico to Give U.S. More Water From Their Shared Rivers (New York Times)
•  Welcoming Mexico’s Water Deliveries to the United States and Steps to Meet 1944 Water Treaty Requirements (U.S. State Department)
•  México y los Estados Unidos anuncian acuerdo sobre las asignaciones de agua del río Bravo conforme al Tratado de 1944 (Gobierno de México)
• Get Involved: AGU Science Policy Action Center

The United States and Mexico renegotiated parts of the treaty last year under the Biden Administration, allowing Mexico to meet its treaty obligations with water from other rivers, tributaries, or reserves. Yesterday’s announcement marks a commitment from Mexico to adhere to the amended treaty, rather than striking a new deal.

As climate change has worsened drought conditions in Mexico the country has struggled to meet the obligations of the treaty while supporting its farmers. Mexico’s current water debt to the United States is roughly 1.3 million acre-feet (420 billion gallons). Mexico’s president Claudia Sheinbaum acknowledged this water debt but said that Mexico has been complying with the treaty to “to the extent of water availability.”

In 2020, tensions over these water deliveries boiled over into violence: Mexican farmers rioted and seized control of a dam near the U.S.-Mexico border to halt deliveries. Mexican officials worry that increasing water deliveries during the hottest and driest months of the year will once again spark civil unrest among farmers.

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

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We've discovered that a meteorite struck northwest Scotland 1 billion years ago, 200 million years later than previously thought. Our results are published today in the journal Geology.