EOS

Reports from the scenes of natural disasters—raging wildfires, unrelenting floods, violent ground shaking, and devastating tornadoes and hurricanes—fill our news feeds every day. These hazards cause deep disruptions to the health of humans and ecosystems and threaten the safety and integrity of buildings and infrastructure.

The severity and frequency of some natural hazards are increasing with climate change. But humans are contributing to the problem in another way: building structures in hazard zones. In a new study that aims to determine the role development plays in the overall risk of natural hazards, Iglesias et al. looked at how development in the contiguous United States has influenced natural hazard risks to structures. They looked at the changes in the number and distribution of buildings between 1945 and 2015 and how development changed people’s exposure to natural hazards.

The researchers first made a hazard map of the United States that included earthquake, wildfire, hurricane, tornado, and floods with data from federal agencies and Fathom (for flood data). Then they identified “hazard hot spots” that correspond to areas where the frequency or intensity of an event falls in the top 10%. Although hazards tend to congregate in certain areas—hurricane risk is high around the Gulf Coast, for example—there can be some spillover into other areas.

When scientists or policymakers look at exposure risk to natural hazards, population density is often a key factor—for instance, the number of people who would be affected by a tornado. But in this study, the researchers focused more on the presence of structures, information they obtained from Zillow’s housing and property database. Their analysis included buildings like homes, stores, schools, and hospitals.

The researchers found that a third of the country contained hazard hot spots, but about 57% of structures sit within these hot risk areas. This is especially the case in earthquake- and hurricane-prone areas, where the density of structures has increased faster than the national trend.

What’s more, there are many structures that are at risk for more than one natural hazard. In the western United States, earthquakes and wildfires could occur in the same area, and floods and tornadoes (and sometimes hurricanes) can threaten the middle and southeastern regions. The explosion of development over 7 decades has ballooned the number of structures at risk of multiple hazards from around 173,000 in 1945 to more than 1.5 million in 2015.

The authors note that development patterns should be taken into consideration to fully capture the risk from natural hazards. And they explain that as climate continues to change, monitoring the occurrence and intensity of weather-related events will help refine the hazards of the future. (Earth’s Future, https://doi.org/10.1029/2020EF001795, 2021)

—Sarah Derouin, Science Writer

This is an authorized translation of an Eos article. 本文是Eos 文章的授权翻译。

太阳持续不断地放射出高能粒子流，其中一部分可以到达地球。这种粒子流的密度和能量构成了空间天气的基础，它会干扰卫星和其他航天器的运行。该领域一个尚未解决的关键问题是，太阳发射的高能粒子爆发达到什么频率，其强度会足以破坏或摧毁太空电子设备。

确定此类事件发生率的一个很有前景的方法是树木年代学记录。这种方法依赖于太阳能量粒子(solar energetic particle, SEP)撞击大气的过程，该过程引发连锁反应，产生碳-14原子。这种原子随后可以被整合到树木的结构中；因此，树木年轮中碳-14原子的浓度可以指示特定年份中SEP的影响率。

迄今为止，文献中已详细描述了三次极端的SEP产生事件，大约发生在公元前660年、公元774-775年和公元992-993年。每一次事件都比太空探索时代的任何测量要强烈一个数量级。Miyake等人描述了一个发生在公元前5411年至公元前5410年之间的事件。由于这次爆发，北半球的大气碳14每年增加了0.6%，持续了好几年才降至正常水平。

作者通过从三个分散地区采集的树木样本推断了这一事件的存在：加利福尼亚的狐尾松、芬兰的苏格兰松和瑞士的欧洲落叶松。每个样本都分离出了独立的树木年轮，每个年轮上的物质都经过加速器质谱测定以确定其碳-14含量。

研究人员利用统计方法，发现了一种与太阳11年周期相一致的碳-14小波动模式；记录在年轮上的事件发生在太阳活动高峰期。值得注意的是，其他证据表明当时太阳也经历了一个长达数十年的活动增长时期。

如果一次极端SEP爆发的确是造成额外碳14的原因的话，那么这些观察还可以帮助预测未来的事件。然而，树木年轮的测量无法排除其他地外原因，比如附近的超新星爆炸。作者认为，要想得到明确的结论，还需要对从冰芯中提取的铍和氯进行同位素测量。(Geophysical Research Letters, https://doi.org/10.1029/2021GL093419, 2021)

-科学作家Morgan Rehnberg

This translation was made by Wiley. 本文翻译由Wiley提供。

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Natural disasters such as floods and droughts have affected the earth and shaped human activities throughout its long geologic and more recent human history. The stakes in managing the risk are now higher because of floods’ economic and social costs on high population centers and the drastic effects of droughts on global food security. The problems have taken some urgency because of global threats of rapid urban population growth and climate change affecting regional and local weather. In many problems of nature such as these, advances in scientific knowledge will help. However, it is not clear whether just following the science helps in policymaking. Di Baldassarre et al. [2021] postulate that answers are not simple, and the team provides a range of citations to support their reasoning and for follow-up reading. They recommend that, as multiple disciplines contribute to the needed policy-relevant science, we need integrated interdisciplinary research and methods to cope with uncertainty.  The challenge remains of how to encourage politicians to make policy through rational thinking based on these ideas.

Citation: Di Baldassarre, G., Cloke, H., Lindersson, S., Mazzoleni, M., Mondino, E., Mård, J., et al. [2021]. Integrating multiple research methods to unravel the complexity of human-water systems. AGU Advances, 2, e2021AV000473. https://doi.org/10.1029/2021AV000473

—Tissa Illangasekare, Editor, AGU Advances

 

Photosynthesis is thirsty work—it requires just as much water as it does carbon dioxide, and in deserts, it can all but shut down. Without the organic carbon photosynthesis provides, life in arid climes must either compete for scraps blown in from afar or wait for rain. But despite the twofold challenge of drought and starvation, microbes in many desert soils somehow manage not only to survive but to flourish.

“The enigma has always been: Why are deserts diverse?” said Sean Bay, a microbial ecologist at Monash University in Melbourne, Australia. “Why do we see so many rich microbial communities?”

In Israel’s Negev Desert, microbes are pulling off a metabolic magic trick. By “burning” hydrogen gas scavenged from the air, they can scrape together enough energy to survive dry spells—and some can even use hydrogen to fuel carbon fixation.Bay and his colleagues may have found an answer in the hyperarid soils of Israel’s Negev Desert, where microbes are pulling off a metabolic magic trick. By “burning” traces of hydrogen gas scavenged from the air, they can scrape together enough energy to survive dry spells—and some can even use hydrogen to fuel carbon fixation. The researchers announced their findings in The ISME Journal: Multidisciplinary Journal of Microbial Ecology.

The Negev Desert is a natural experiment in how microbes adapt to aridity. “Over a relatively short spatial scale—[the farthest sampled] soils were approximately 160 kilometers apart—you have got distinct climatic zones,” said Bay. Driving south from the Judea Hills, the landscape of green chaparral gives way to dramatic swaths of chalky brown and tan. The researchers gathered 72 soil samples along this natural climatic gradient for analysis in their Melbourne lab, where they hoped to discover genetic or chemical clues explaining the unexpected diversity of microbial communities in arid environments.

Desert Microbes Run On Hydrogen Fuel

Specifically, Bay and his colleagues wanted to find out how the Negev Desert microbes might be using hydrogen for survival.

“In these large swaths of arid ecosystems, trace gas metabolism is likely a really important part of microbial metabolism,” explained Laura Meredith, an environmental scientist at the University of Arizona who was not involved in the new research. Trace gases like hydrogen and methane are naturally present in the air, together accounting for about 0.1% of atmospheric gases. Some microbes have specialized enzymes that can capture trace gases and exploit them for energy when there are few other resources available.

Previous studies showed that microbes can use hydrogen to run their life-support systems while waiting for favorable conditions in a kind of stasis, or dormancy. And Bay suspected that hydrogen might be fueling carbon fixation in deserts, too.

“Something seemed off about the accepted model,” he said. “These [photosynthesizing] communities of cyanobacteria—which are really, really low abundance in these soils—are providing enough energy, or organic carbon?”

Bay’s bet on hydrogen appears to have been justified. He and his colleagues discovered genes associated with hydrogen metabolism were widespread across the samples and enriched in samples from drier soils. Microbes inhabiting the driest soils consumed hydrogen 143 times faster than those in samples collected from the greener Judea Hills. The research team even found evidence that soil microbes from across the climatic gradient will “burn” hydrogen to power carbon fixation as a supplement to photosynthesis when provided with a bit of water.

“It’s like adding another ecological player, another strategy,” said Meredith.

Implications for the Carbon Cycle

Bay saw the results as evidence that trace gas metabolism is far more widespread than previously thought—not a niche process used by a handful of exotic bacteria, but something that takes place across entire ecosystems. And according to Meredith, microbes that use trace gases like hydrogen to maintain and create new biomass could also be tinkering with Earth’s carbon cycle.

“Carbon cycling in arid ecosystems, we know, is a leading contributor to overall carbon cycle variability at a global scale,” she said, “so anything that’s contributing to carbon fixation or carbon stabilization in the massive swaths of arid lands around the world is also important.”

Bay agreed. “I think that’s a really exciting part of this research…it’s not just about discovering curious new ecosystems or curious new processes. There are actually really important implications.”

—Elise Cutts (@elisecutts), Science Writer

This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

Las cunas de la vida en las regiones neotropicales del planeta siguen siendo un misterio para los geólogos y paleontólogos. Pero una nueva investigación proporciona algunas pistas, sugiriendo que los neotrópicos, un área geográfica que consta de América Central y del Sur, el Caribe y las regiones tropicales del sureñas de América del Norte, eran significativamente diferentes antes y después del impacto del asteroide Chicxulub hace 66 millones de años.

Las selvas neotropicales albergan más de 90.000 especies de plantas, casi el 50% de la biodiversidad total del planeta. Estos ecosistemas producen altas tasas de oxígeno, además de secuestrar dióxido de carbono de la atmósfera, lo que ayuda a equilibrar el clima global.

Mónica Carvalho, paleobióloga colombiana del Instituto Smithsonian de Investigaciones Tropicales en Panamá, ha pasado los últimos 12 años explorando los bosques y las minas de carbón de su país natal. Con cada viaje, ha recolectado miles de hojas fósiles y rocas que contienen polen microscópico, los cuales son evidencia de vida vegetal antigua.

Mónica Carvalho, en la foto, ha recolectado miles de fósiles raros del paisaje neotropical de Colombia. Crédito: Fabiany Herrera

Carvalho y su equipo acumularon una colección de fósiles del Cretácico y Paleoceno, períodos del tiempo geológico que fueron separados por el impacto de un asteroide que mató al 75% de las especies vivas. El equipo cuantificó qué plantas desaparecieron y cuáles sobrevivieron al evento y qué tipo de cambios atravesó el ecosistema.

Sus resultados indicaron que durante el Cretácico, los bosques neotropicales se caracterizaban por doseles abiertos y estaban dominados por helechos, pinos y algunas plantas con flores. Pero el paisaje cambió drásticamente en el Paleoceno, con bosques dominados principalmente por plantas con flores, leguminosas y doseles cerrados. Este patrón muestra los bosques densos y oscuros que conocemos hoy.

El artículo fue publicado en Science.

Resolviendo el rompecabezas

La mayoría de los datos existentes sobre lo que sucedió después del impacto de Chicxulub provienen de investigaciones en América del Norte y la Patagonia, principalmente porque es “relativamente fácil” encontrar fósiles intactos allí, dijo Viviana Barreda, paleontóloga del Museo Argentino de Ciencias Naturales Bernardino Rivadavia, en Buenos Aires. El paisaje ahí es “casi una estepa sin vegetación que lo cubra, el sueño de todo geólogo y paleontólogo”, dijo Barreda, quien no formó parte del estudio.

Encontrar fósiles preservados en los trópicos es extremadamente difícil debido a la gran cantidad de vegetación, así como a las altas tasas de oxígeno y humedad que degradan rápidamente el polen y las esporas.Pero encontrar fósiles preservados en los trópicos es extremadamente difícil debido a la gran cantidad de vegetación que cubre el suelo. Además, las altas tasas de oxígeno y humedad de los trópicos degradan rápidamente el polen y las esporas, lo que reduce la probabilidad de que se conserven.

Para Paula Sucerquia, geóloga de la Universidad Federal de Pernambuco en Brasil que no participó en el nuevo estudio, “este problema provocó un vacío en la historia paleontológica de Colombia”, razón por la cual los investigadores no sabían qué había sucedido con las plantas en el neotrópico después del impacto. Los resultados de Carvalho, sin embargo, “aportan información importante sobre las piezas que faltan en el rompecabezas paleontológico”.

El análisis incluyó 50,000 muestras de polen fosilizado de 39 localidades colombianas y más de 6,000 muestras de hojas fosilizadas de los municipios de Guaduas, Bogotá y la mina de carbón Cerrejón en La Guajira.

(Izquierda) Los fósiles como éste son raros porque el clima del neotrópico desalienta su formación; (derecha) Mauricio Gutiérrez recolecta fósiles maastrichtianos en una mina de carbón en Cundinamarca. Crédito: Fabiany Herrera

Las plantas y el polen fosilizado brindan información sobre lo que sucedió en un lugar específico en un momento específico. “Son como una fotografía. Se quedan congelados [en el tiempo]”, dijo Sucerquia.

Los investigadores también encontraron evidencia de cómo los insectos cambiaron sus patrones de alimentación. Aunque algunas especies de plantas del Cretácico fueron mordidas selectivamente, las plantas del Paleoceno mostraron mucho más daño. “Esto muestra que el bosque cambió no solo en su estructura y especies de plantas, sino también en sus interacciones ecológicas”, dijo Carvalho.

Mirar hacia atrás para avanzar

Después del impacto del asteroide, las cenizas y los sedimentos de minerales como el nitrógeno y el fósforo cubrieron el suelo, aumentando la fertilidad del suelo y permitiendo que las especies más adaptables, como las plantas con flores y las leguminosas, se apoderaran de los bosques. Además, la extinción de los dinosaurios herbívoros gigantes permitió que los árboles crecieran más juntos, formando densos parches de vegetación, dijeron los investigadores.

Estos cambios probablemente no fueron inmediatos, dijo Barreda. Los flujos de gases de efecto invernadero también alteraron la composición de los bosques en todo el planeta.

Para Carvalho, los resultados del estudio muestran cómo los ecosistemas tropicales pueden recuperarse después de catástrofes ecológicas, pero al mismo tiempo demuestran lo lento que es el proceso de recuperación.

“La vida tardó alrededor de 6 años en regresar, y aunque la catástrofe ecológica que los humanos están provocando por la deforestación no es de la misma magnitud, sigue el mismo camino”, dijo. “La vida definitivamente regresará, pero ¿seremos capaces de esperar?”

—Humberto Basilio (@humbertobasilio), Escritor de ciencia

This translation by Mauro González Vega (@MGonVe) and @Anthnyy was made possible by a partnership with Planeteando. Esta traducción fue posible gracias a una asociación con Planeteando.

It has been 8 years, one pandemic, and a slew of wildfires, storms, and heat waves since the last United Nations climate assessment report was released in 2013. During that time, 191 parties signed the Paris Agreement; the United States (the world’s second-largest emitter) left and reentered the agreement; renewable energy outpaced coal in the United States and all fossil fuels in Europe for the first time; and greenhouse gas emissions crashed worldwide during stay-at-home orders before springing back.

It is with this backdrop that the Intergovernmental Panel on Climate Change (IPCC) unveiled its new assessment of global climate science.

Started in 1988 by the U.N. Environment Programme and the World Meteorological Organization, the IPCC supplies policymakers with policy-neutral information about climate change. The IPCC does not conduct its own research­: It summarizes the work by global experts and notes where disagreements lie. More than 200 authors from 66 countries in the organization’s Working Group I wrote the latest report. The document includes more than 14,000 cited references. All eyes are turning to October’s U.N. Climate Change Conference of the Parties (COP26) in Glasgow, Scotland, where the latest report will inform negotiations.

The report predicts that warming will reach 1.5°C by the early 2030s, exceeding the lower goal of the Paris Agreement. How much further the temperatures rise will depend on emissions. Each of the world’s top three emitters—China, the United States, and the European Union­—have goals to slow the rate of emissions this decade.

The IPCC report spells out what could happen if we don’t meet these targets: The Arctic could be ice free by mid- to late century. Sea level could rise by a meter by 2100, inundating cities. And extreme heat waves could become more intense and frequent.

Here are five takeaways.

1. Global Warming Thus Far

For the past 2,000 years, global surface temperatures stayed relatively constant until an unprecedented rate of warming began in the mid-20th century. Today, the planet’s temperature is 1.09°C (0.95°C to 1.20°C) above what is was in 1850–1900. Historical data came from paleoclimate archives, and recent observations are direct measurements. Shading shows 5% and 95% confidence intervals for historical measurements. Credit: Jenessa Duncombe. Source: IPCC [2021]The takeaway: The world has warmed 1.1°C compared to preindustrial levels, and regional hot spots already feel the heat, but we have not surpassed the Paris Agreement goal of limiting warming to 1.5°C or 2°C.

In the past 100,000 years, Earth has been this warm only once. Around 6,500 years ago, the planet’s temperatures were about on par with what they are today. The difference? That warming was part of an ebbing and flowing cycle of ice sheets from natural variation of Earth’s orbit. Today’s temperatures come from pollution that will continue to grow unless we hit the brakes.

Today, some areas on Earth have already warmed beyond 2°C. The Washington Post reported in 2019 that 71 counties in the United States have already warmed past 2°C. Temperatures in the Arctic are rising at least twice as fast as the rest of the world. Islands are particularly at risk: The rallying cry for 1.5°C originated from an alliance of 44 small island states that commissioned a study in 2008 and became alarmed that 2°C warming would threaten their survival.

Previous climate agreements favored a 2°C rise, but mounting evidence suggests that keeping temperatures to a 1.5°C rise would greatly reduce extreme heat, instances of extreme precipitation and drought, sea level rise, species loss and extinction, and ocean acidification.

Global temperatures have a 20% chance of reaching 1.5°C above preindustrial levels during at least one of the next five years, according to the U.K. Met Office and the World Meteorological Organization.

2. Future Warming Pathways

The global average temperature at the end of the century will be determined by the amount of greenhouse gas emissions over the next several decades. The two shared socioeconomic pathways (SSP) that stay below 2°C (very low emissions and low emissions) require net zero emissions by mid- to late century and carbon removal. There are five scenarios: very low emissions (SSP1-1.9), low emissions (SSP1-2.6), midlevel emissions (SSP2-4.5), high emissions (SSP3-7.0), and very high emissions (SSP5-8.5). Shading shows the 5% and 95% confident intervals. Credit: Jenessa Duncombe. Source: IPCC [2021]The takeaway: Keeping warming below 2°C, and perhaps 1.5°C, is still possible; it’ll take immediate and sustained emissions cuts.

Future illustrative scenarios of warming are one of the hallmarks of IPCC reports. The scenarios include natural forcing like solar activity and volcanoes, along with social and economic forces that drive greenhouse gas emissions, land use, climate mitigation, and air pollution.

The scenarios will underpin international policy, research, and activism for years to come.The scenarios aren’t predictions; they can’t determine the fate of global warming. Instead, they provide road maps. The scenarios often underpin international policy, research, and activism for years to come.

The new report has five scenarios: two with low emissions, one with intermediate emissions, and two with high emissions. The very low emissions scenario meets the 1.5°C Paris Agreement goal with likely warming of 1.4°C by 2100—but it overshoots the target to just above 1.5°C midcentury before decreasing to 1.4°C. The low emissions scenario reaches 1.8°C by 2100, just skirting under the high bounds of the Paris Agreement. Midlevel emissions hit 2.7°C, high emissions clock in at 3.6°C, and very high emissions extend to 4.4°C in 2100.

Climate scientist and IPCC Working Group I cochair Valérie Masson-Delmotte said that the midlevel emissions scenario most closely resembles the pledges made by countries to plateau emissions until around 2030. The highest emissions scenarios represent futures without any climate mitigation.

The last IPCC assessment in 2013 included just one low emissions scenario that kept warming under 2°C.

3. Carbon Dioxide’s Oversized Footprint

Aerosols and land use changes cool global climate, whereas greenhouse gases warm it. There are five scenarios: very low emissions (SSP1-1.9), low emissions (SSP1-2.6), midlevel emissions (SSP2-4.5), high emissions (SSP3-7.0), and very high emissions (SSP5-8.5). Shading within the total (observed) warming shows global temperature rise to date. Global surface temperature is measured relative to 1850–1900. Credit: IPCC [2021], Figure SPM.4The takeaway: Net zero carbon dioxide (CO2) is a requirement for any long-term climate solution.

Greenhouse gases include CO2, methane, nitrous oxide, and fluorinated gases. When headlines or politicians talk about “net zero carbon” or “carbon neutral,” it may seem like they’re leaving out other greenhouse gases. But although most climate targets aim to reduce greenhouse gas emissions as a group, the essential ingredient is carbon dioxide.

The graph above illustrates why.

Warming is overwhelmingly controlled by the amount of carbon dioxide in the atmosphere. There is a nearly linear relationship between cumulative carbon dioxide increasing and global surface temperatures rising. The latest report even has an equation for it: Every 1,000 metric gigatons of cumulative CO2 emissions (GtCO2) will likely cause planetary warming of 0.45℃.

4. Annual Carbon Dioxide Emissions

In the very low emissions scenario, annual carbon dioxide emissions drop practically to zero by 2050. In the low scenario, CO2 emissions drop to zero between 2070 and 2080. The other scenarios never achieve zero CO2 emissions. Credit: Jenessa Duncombe. Source: IPCC [2021]The takeaway: The most aggressive scenario to limit warming requires sharp CO2 cuts per decade, net zero CO2 by 2050, and carbon capture.

Carbon emissions come from burning oil, gas, and coal; these fossil fuels drive heating, electricity, agriculture, land use, industry, and transport.

During COVID-19, emissions fell an unprecedented 2.6 GtCO2 in 1 year, according to research published in Nature Climate Change in 2021. Because the emissions cuts during the pandemic were temporary, those reductions won’t have any detectable effect on CO2 concentrations or temperature. The researchers of the Nature Climate Change study predict that emissions cuts of about this scale (1–2 GtCO2) are necessary at least through the 2020s to meet the Paris Agreement.

5. Carbon Extraction

Carbon dioxide typically stays in the atmosphere for centuries to millennia, but carbon removal accelerates the natural cycle to store excess carbon in soil, plants, or water. A simplified computer model shows how long Earth systems take (years to centuries) to rebound following peak CO2 emissions (vertical gray dashed lines in each plot). Credit: IPCC [2021], FAQ 5.3. Click image for larger version.The takeaway: The two scenarios in the report that limit warming below 2°C use carbon removal from the atmosphere during the latter part of the century.

Carbon naturally cycles through the soil, water, plants, and air continuously. We can draw carbon out of the atmosphere by planting trees, sequestering carbon in agricultural soil, restoring ocean ecosystems that store carbon, and applying carbon capture and storage technology.

Model simulations in the latest report suggest that removing carbon dioxide from the atmosphere drops temperatures in just a matter of years.

Although some carbon removal methods show promise, the practice remains in the research and development phase and would require deployment at massive scales, according to the report. Carbon capture could cause undesirable effects such as losses of biodiversity, water, or food production.

More to Come

The report by Working Group I on the physical science is one of four expected over the next year; reports from Working Group II in February 2022 and Working Group III in March 2022 will explore the impacts of climate change and mitigation, respectively. The synthesis report in November 2022 will combine all findings.

—Jenessa Duncombe (@jrdscience), Staff Writer

References

Intergovernmental Panel on Climate Change (IPCC) (2021), Summary for policymakers, in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by V. Masson-Delmotte et al., Cambridge Univ. Press, Cambridge, U.K., in press.

Ozone plays a vital role in Earth’s climate system. In the stratosphere, which begins about 6 miles (9.7 kilometers) off the ground, ozone protects the planet from harmful ultraviolet radiation. Lower in the atmosphere, however, the molecule is an air pollutant injurious to both humans and plants, as well as a greenhouse gas.

Ozone interacts with forests through a process known as dry deposition, often with harmful consequences. In this process, turbulence in the atmospheric boundary layer brings ozone to the surface where reactions on and inside leaves and soil remove ozone from the air. Ozone injury to plants results from ozone reactions inside leaves and can alter carbon and water cycling.

The mechanics of dry deposition are not completely understood, however. While we know that turbulent eddies in the atmosphere transport ozone to surfaces onto which the gas can be deposited, one remaining question is whether the organized nature of these eddies, known as organized turbulence, influences dry deposition. Uncertainty related to the mechanics of dry deposition makes it harder to understand ozone in the lower atmosphere and ozone’s impacts on both plants and humans.

In a new study, Clifton and Patton use high-resolution computer simulations to examine the relationship between turbulent eddies and leaf ozone uptake. The authors hypothesized that organized turbulence generates local fluctuations in temperature, wind, and humidity that together with local changes in ozone might result in different rates of ozone uptake by leaves. They call this variation in leaf uptake “segregation of dry deposition.” By taking segregation of dry deposition into account, scientists can better predict ozone dry deposition, the authors say.

The results showed that organized turbulence did not create more efficient areas of ozone uptake in the forest canopy. In other words, higher concentrations of ozone in some air motions together with higher leaf uptake in the same air motions did not result in more ozone uptake by the canopy. Therefore, the findings are a null result and indicate that segregation of dry deposition is likely an unimportant factor in a forest’s ozone budget. Null results are less likely to be published but play an essential role in figuring out important natural processes. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2021JG006362, 2021)

—Aaron Sidder, Science Writer

High winds and flooding storm surges driven by tropical cyclones cause some of the deadliest and most damaging weather-related conditions around the world. The rainfall that cyclones bring compounds these conditions and, in hilly or mountainous areas, can trigger landslides that cause even more widespread and devastating impacts. When extreme precipitation occurs over short time frames, hillslopes may become saturated and critically unstable. The most intense storms can trigger thousands of landslides in mountainous areas, as was dramatically illustrated in Puerto Rico in September 2017, when Hurricane Maria’s rains left the landscape scarred by roughly 40,000 landslides.

Locating landslides quickly helps authorities direct resources to where they are most needed to save people and critical infrastructure.Before and during a major cyclone, disaster responders need information about where landslides are likely to occur. In the aftermath, locating landslides quickly helps authorities direct resources to where they are most needed to save people and critical infrastructure. However, this information is often unavailable during an event response or is presented only for small regions, constraining the effectiveness of response efforts.

Satellite data provide regional perspectives of landslide hazards from major cyclones. New satellite constellations (groups of satellites functioning together) can image most of the world every day, helping scientists to detect the locations of landslides as they occur. In addition, using satellite data to characterize extreme rainfall allows us to model where landslides might occur in near-real time.

Our research group at NASA is developing a range of tools to help prepare for and respond to landslide disasters. These tools include rapid landslide mapping as well as modeling at different timescales to help direct response activities soon after a tropical storm dissipates and inform decisionmaking throughout the disaster life cycle.

Recently, we supported the NASA Disasters Program to deliver experimental products during significant disasters. In late 2020, a pair of major hurricanes allowed us, for the first time, to combine and test all our research in response to real events in real time and to gain valuable feedback from end users about the efficacy and utility of the tools we are developing.

Eta, Iota Delivered a One-Two Punch

The busy 2020 Atlantic hurricane season gave rise to 30 named storms—the highest number on record—including 13 hurricanes. In late October, warm sea surface conditions in the Caribbean caused Tropical Storm Eta to intensify rapidly. Eta made landfall south of Puerto Cabezas, Nicaragua, as a category 4 hurricane on 3 November. The storm tracked west and then northeast over Honduras and Guatemala before it reentered the Caribbean Sea and continued northeast. The storm strengthened again before making further landfalls in Cuba and Florida. Intense rainfall led to catastrophic flooding and landslides throughout Central America, with Guatemala, Honduras, and Nicaragua facing the most severe impacts.

Eta and Iota were among the worst disasters to strike Central America in several decades. Combined, the two storms led to hundreds of landslide-related fatalities.Less than a week after Eta dissipated, Tropical Storm Iota became the final named storm of the season on 13 November. Iota also strengthened rapidly, becoming a category 5 hurricane by 16 November. The storm weakened marginally to a category 4 storm prior to hitting Nicaragua on 17 November, but the location of landfall was only 25 kilometers south of where Eta had first landed. The combined damage from Eta and Iota has been estimated at over $8 billion, with Eta causing more than $6 billion in damage in Central America.

Landslides resulting from Hurricane Eta claimed lives in Costa Rica, Guatemala, Honduras, and Nicaragua. One particularly deadly landslide killed more than 100 people in the village of Queja, Guatemala. Hurricane Iota also triggered fatal landslides in Honduras and Nicaragua, and some of the storm’s outlying rainbands even triggered deadly landslides in Colombia. Combined, the two storms led to hundreds of landslide-related fatalities, and although not as deadly as Hurricane Mitch in 1998, Eta and Iota were among the worst disasters to strike Central America in several decades.

A Real-World Test for Models and Observations

The dire conditions from the storms prompted immediate disaster response and recovery (DRR) efforts across the affected regions by various national and international agencies. During these efforts, we provided partner agencies with the latest versions of our landslide tools, putting them into practice in real experimental settings. These tools fall into two categories: predictive models of landslide effects before and during events and rapid observations of landslide locations in the immediate aftermath.

The Landslide Hazard for Situational Awareness (LHASA) tool, first deployed in 2017, provides near-real-time nowcasts of locations where landslide hazards are elevated by comparing precipitation data from the Global Precipitation Measurement mission (GPM) from the past 7 days with long-term precipitation records and a global landslide susceptibility map [Kirschbaum and Stanley, 2018; Stanley and Kirschbaum, 2017].

Fig. 1. This map illustrates results from the Landslide Hazard for Situational Awareness model, which assesses landslide hazard (purple shades) and population exposure to these landslide hazards (teal), during Tropical Storm Eta on 5 November 2020. Credit: NASA Earth Observatory

The latest version of the LHASA model uses a machine learning approach to estimate probabilistic landslide hazards around the world every 3 hours. We combine this hazard output with data sets detailing population and infrastructure to estimate landslide exposure—a critical step forward that allows stakeholders to make actionable decisions (Figure 1). Combining geophysical hazard science with socioeconomic data mirrors the shift in the broader natural hazards research community toward more interdisciplinary disaster research and is in line with the objectives of the United Nations’ Sendai Framework for Disaster Risk Reduction 2015–2030, which recognizes the increasing complexity of disasters and diversity of impacts on human systems.

During Eta and Iota, we also tested our landslide forecast product, which uses rainfall forecast data from the NASA Goddard Earth Observing System (GEOS) suite of computerized forecasts to model locations where intense rainfall is likely to trigger landslides in the coming days. Although this data product remains experimental, the landslide forecasts it produced for these hurricanes showed moderate and high levels of forecasted hazard in areas where landslides were reported or observed. We anticipate that this landslide forecast may address crucial needs of disaster response stakeholders prior to major rainfall events in the future.

Images of the Aftermath

As clouds clear after a cyclone, the full extent of the damage becomes clearer. Satellite radar data have been used to detect changes in topography due to landslides, even through clouds. However, optical imagery remains the most definitive source to determine landslide locations and effects on critical infrastructure like hospitals, power stations, and schools.

Our team recently developed a computerized method called Semi-Automatic Landslide Detection (SALaD) [Amatya et al., 2021], which uses 3-meter-resolution imagery from Planet Labs and 10-meter-resolution Sentinel satellite imagery to rapidly map landslides (Figure 2). Planet Labs’ satellites image much of the world once a day, meaning images can be obtained and landslides can be mapped almost as soon as clouds clear after an event.

Fig. 2. These photos collected by the Sentinel-2 satellite highlight a major landslide event at Queja, Guatemala, triggered by Tropical Storm Eta. The site (a) before the landslide and (b) between Hurricanes Eta and Iota. Major landslide damage can be seen in the center of the image. Credit: Contains modified Copernicus Sentinel data 2020, processed by the European Space Agency

Using the hazard model results obtained from LHASA in conjunction with media reports, we can home in on regions of interest quickly to find areas most affected by landslides and identify where landslide mapping would be beneficial—in some cases within 2 days. This identification and mapping can help estimate impacts on rural communities that have been cut off from outside communication. In addition, landslide mapping guided by hazard estimates can help us discover landslides in unpopulated areas to provide more comprehensive regional maps of triggered landslides.

Information When It’s Needed

We were able to map landslides between the end of Hurricane Eta and before Iota made landfall, which allowed us to distinguish the effects of the two storms.On the basis of informal discussions with disaster responders, the most critical time frame for disaster response information is within a week of an event. The rapid return periods of Planet Labs imagery allow us to build maps of landslide locations well within this time frame, providing information when it is most needed. Hurricanes Eta and Iota illustrated the value of this rapid response—we were able to map landslides even in the short cloud-free interval between the end of Hurricane Eta and the time before Iota made landfall, which allowed us to distinguish the effects of the two storms.

The purpose of developing the hazard and exposure estimates is to provide stakeholders with information to help support decisionmaking during major catastrophes, information that is especially valuable for remote regions and areas in which little information is available from the ground. During the two hurricane events last fall, we worked with the NASA Disasters team to help inform partner agencies assisting in DRR efforts in the region about potential landslide impacts. Our partners included the U.S. Department of Defense Southern Command (SOUTHCOM), the intergovernmental Coordination Center for the Prevention of Disasters in Central America and the Dominican Republic (CEPREDENAC), and the Pacific Disaster Center (PDC), an applied research center managed by the University of Hawaii.

This was the first time that each of the data products described above was provided to end users to support disaster response during an event. Some of the new users from CEPREDENAC and SOUTHCOM indicated that they valued having the regional perspective on landslide hazard and exposure provided by the tools. In particular, they emphasized that combining exposure information with hazard assessments helped them to prioritize the distribution of resources during their responses. In addition, users stated that the landslide forecast information may be the most useful tool for future events.

Field testing of our research is the best way to learn quickly what tools provide actionable information at relevant timescales and where additional work is needed. And with each test, we can incorporate feedback iteratively to keep improving the tools and guiding future developments.

More work is needed to ensure that all relevant hazard and exposure information reaches authorities and the public in areas at high risk of cyclone-driven landslides. However, we suggest that the combined suite of products described here can serve decisionmakers, especially those facing a dearth of detailed information from local observations, as valuable tools of triage in determining where emergency response is needed.

Scintillations are random fluctuations of radio signal amplitudes and/or phases caused by irregularities in the ionosphere, which impact global positioning system (GPS) signals. Makarevich et al. [2021] used data covering a period of 166 days from the incoherent scatter radar (ISR) at Poker Flat, Alaska (PFISR) and nearby global positioning system (GPS) receivers to examine the generation mechanisms and possible source regions of ionospheric scintillations.

Scintillations have been traditionally described using the S4 (amplitude) and σϕ (phase) indexes, but when these are unavailable a proxy rate of change of total electron content (ROTI) index is often used. The authors find that the ROTI index exhibits significant correlation and an approximately linear relationship with the phase scintillation metric σϕ in the auroral region while the amplitude scintillation S4 shows no relationship with ROTI or σϕ. The probability of high scintillation measured using ROTI or σϕ also increases with auroral activity. A strong connection between the auroral particle precipitation into the E-region and scintillation (ROTI and σϕ) was noted, indicating that the ionospheric E-region is a key source region for phase scintillation at auroral latitudes. The authors also showed that for one event, scintillations occurred on the trailing edge of a well-defined propagating density enhancement in the E-region, suggesting that the gradient-drift instability was the possible candidate for the plasma structuring and scintillations.

This paper adds to the growing body of evidence that ROTI can be used as a useful proxy for phase scintillation and that the ionospheric E-region is an important source region for ionospheric scintillations at auroral latitudes.

Citation: Makarevich, R. A., Crowley, G., Azeem, I., Ngwira, C., & Forsythe, V. V. [2021]. Auroral E-region as a source region for ionospheric scintillation. Journal of Geophysical Research: Space Physics, 126, e2021JA029212. https://doi.org/10.1029/2021JA029212

—Michael P. Hickey, Editor, JGR: Space Physics

The Summer Olympic Games bring together top athletes from around the world to compete and showcase their skills every 4 years like clockwork—excepting the most recent games, of course. As issues of environmental sustainability continue to gain public and political traction, the Olympic Games have become a focal point for environmentalists and academics seeking to raise awareness and evaluate the environmental impacts of international sporting events.

But those impacts extend beyond the 4-year games: Thirty-two International Sports Federations (IFs) participate in the Summer Olympic Games, each of which may host dozens of international competitions every year. Each federation’s progress toward sustainability contributes to the overall environmental impact of the Olympic Movement. However, a new report found that most IFs have made little to no progress over the past decade toward the environmental sustainability goals set by the Olympic Movement, and even fewer sports organizations have sustainability goals of their own.

“Climate change poses a multitude of risks for the sporting sector,” Dominique Santini of the University of Exeter in the United Kingdom, lead researcher on the report, said in a statement. “Immediate climate change mitigation among sports organizations is therefore vital.”

Who Medals and Who Isn’t Competing?

The researchers mined environmental sustainability information released during 2010–2020 on federations’ websites, in memos, and in strategic plans for the future and also looked at more informal communications on Twitter. The team took into account not only how many times an organization communicated about environmental sustainability but also what they mentioned (e.g., just using buzzwords, talking about a problem, or reporting progress made toward solutions), whether the communication was prompted by an external factor like governance, and whether the communication was backed up by action.

In the new ranking system, World Sailing placed first in environmental sustainability progress, followed by World Athletics, World Rowing, and Fédération Internationale de Football Association (FIFA). Information from those four tier 1 federations included environmental sustainability terminology, ethical corporate communications practices, proof of commitment, and an environmental sustainability strategy. World Sailing and World Athletics also shared a management framework for their strategies, and World Sailing came out on top by demonstrating accountability and continually reporting on its progress via social media.

“There are significant opportunities for other international federations to integrate environmental sustainability targets into their respective sports.”“Environmental sustainability is one of World Sailing’s strategic priorities, with delivery of our Sustainability Agenda 2030 starting in May 2018 after being unanimously supported by our members,” Dan Reading, head of sustainability at World Sailing, told Eos.

However, from 2010 to 2020, 17 of the 32 international federations did not meet any of these environmental sustainability progress criteria. Furthermore, seven sports—Badminton World Federation, International Gymnastics Federation, International Handball Federation, International Shooting Sport Federation, International Tennis Federation, World Karate Federation, and World Skate—did not mention environmental sustainability at all during that time. The remainder were found to have made some environmental sustainability progress but without having a specific strategy in mind.

“This research paper shows that there are significant opportunities for other international federations to integrate environmental sustainability targets into their respective sports,” Reading added. The report was released on Emerald Open Research in July.

What Hinders or Drives Progress?

The researchers also examined potential drivers of sustainability progress among the IFs. They found that academic literature on the environmental sustainability of the Olympic Movement has disproportionately focused on the 4-year Summer Olympic Games: Literature searches returned 23,000 studies per Olympic Games but only 337 per International Gymnastics Federation event and 22 per International Fencing Federation event. Only five Olympic sports (golf, surfing, football, sailing, and hockey) have received any sport-specific focus in sustainability literature, and only three of those (sailing, football, and surfing) ranked in the top five of making progress.

There was some correlation between a sport’s sustainability progress and its connection to the natural environment—World Sailing, for example, ranked first—but that correlation did not hold for all sports. World Athletics, for example, ranked second, whereas the International Surfing Association ranked fifth and the International Golf Federation ranked eleventh.

Climate activist Greta Thunberg speaks at a climate strike in Switzerland in January 2020. Credit: Markus Schweizer, CC BY-SA 4.0

The researchers found that formal activities related to environmental sustainability, like the release of the fifth Intergovernmental Panel on Climate Change report in 2014, the Paris Agreement in 2015, and various governance-related factors, had little correlation with environmental sustainability communications or strategy. However, more informal environmental activities that penetrated deep into public awareness, like the release of David Attenborough’s Blue Planet II series in 2017 and the rise in climate activism related to Greta Thunberg since 2018, were more closely correlated with shifts in IFs’ communications related to environmental sustainability.

What’s more, even though tweets from IF accounts largely did not reference the Olympic Games, the number of sustainability-related tweets increased just after the 2012 London Games and the 2016 Rio Games (and in the months prior to the original dates of the 2020 Tokyo Games). According to the researchers, the timing suggests that the Olympic Games boost awareness of environmental sustainability issues and prompt a temporary shift in communications strategy but do not directly lead to progress on environmental sustainability.

What stands in the way of international sporting federations making progress toward environmental sustainability? A high level of autonomy granted by the leadership of the Olympic Movement coupled with a lack of accountability toward goals and a scarcity of financial and intellectual support, the researchers speculate. “The International Olympic Committee (IOC) should…establish a mandatory annual environmental sustainability reporting system for International Federations to increase accountability,” Santini said. An IOC-supported platform for shared resources “regarding transferable practices related to funding, procurement, and partnerships” would also help accelerate sports’ progress toward environmental sustainability.

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

The ocean is an important reservoir in the carbon cycle and presently is a sink for atmospheric carbon. The export of carbon(ate) from the ocean to the sediment depends on the ocean chemistry, which is influenced by, among other factors, tectonic events such as mountain building, and calcareous organisms that change and evolve over geological time scales. The exact balance of these fluxes controls the carbonate concentrations in the oceans and is recorded by seafloor sediments. Smith et al. [2021] provide an important contribution in understanding past ocean chemistry with the development of a new proxy for the carbonate chemistry from carbonate facies and sedimentary textures from arid coastal environments. They demonstrate that these proxies are consistent with a rapid expansion of calcifying organisms in the mid-Mesozoic. Notably, they demonstrate that these proxies are one of few that provide insight on ocean chemistry in deep time, as far back as the Precambrian.

Citation: Smith, B., Cantine, M., Bergmann, K., Ramos, E., Martindale, R., & Kerans, C. [2021]. Arid Coastal Carbonates and the Phanerozoic Record of Carbonate Chemistry. AGU Advances, 2, e2021AV000386. https://doi.org/10.1029/2021AV000386

—Vincent Salters, Editor, AGU Advances

Yellowstone National Park, the world’s first and arguably most famous national park, is home to one of the planet’s largest and potentially most destructive volcanoes. The 50- by 70-kilometer Yellowstone caldera complex is so massive that it can really be appreciated only from the air. But although the caldera isn’t always visible on the ground, it’s certainly no secret: Copious thermal features like hot springs and geyser basins dot the landscape and have attracted people to the uniquely beautiful and ecologically rich area for at least 11,000 years.

As people seek to explain the area’s geology, Yellowstone’s unusually active landscape has inspired myths and legends, from Indigenous origin stories to misleading headlines about the future. Every season, recurring bouts of earthquake swarms trigger sensational stories that Yellowstone could be gearing up for another “big one.” But there’s no need to cancel your family vacation to see the park’s free-roaming bison and grizzly bears: The geologists who keep a very close eye on the Yellowstone caldera system say it’s not going to erupt again in our lifetimes.

Becoming Yellowstone

The story of Yellowstone begins around 16.5 million years ago, when a plume of magma began fueling intense bouts of volcanism along the border of what is now Idaho, Nevada, and Oregon. This magma plume, like the one that formed the Hawaiian Islands, is stationary, but as the North American plate moves to the southwest over the hot spot, its surface expression migrates, creating a 750-kilometer-long trail of volcanism, including dozens of calderas, across southern Idaho and into northwest Wyoming.

The movement of the North American tectonic plate over the Yellowstone hot spot has created a trail of volcanic activity across southern Idaho into Wyoming over the past 16.5 million years. Credit: USGS. Click image for larger version.

Around 2.1 million years ago, when the hot spot was centered under the southwest corner of what is now Yellowstone National Park, the volcano’s magma reservoirs filled to bursting, resulting in one of the largest volcanic eruptions in the geologic record. The explosion spewed ash and debris all the way to the Mississippi River, ejecting more than 6,000 times the volume of material erupted during the 1980 Mount St. Helens eruption. As the magma chambers emptied, the overlying layers collapsed, forming a massive caldera.

This cycle of explosive eruptions repeated twice more, around 1.3 million and 630,000 years ago, resulting in three overlapping calderas. In between these events, slow-moving lava flows drastically altered the landscape but didn’t affect the region beyond the immediate area. The last of these lava flows, which formed the Pitchstone Plateau in the southwest corner of the park, erupted around 70,000 years ago, and the volcano has been relatively quiet ever since.

Nobody was around to witness Yellowstone’s last lava flow; humans were not yet living in North America 70,000 years ago. But people have been living in the area for at least 11,000 years, and thousands of artifacts and campsites have been found throughout the park, often concentrated around rivers, lakes, and obsidian sources.

Hot springs dot the shores of Yellowstone Lake, the largest lake in the park. Credit: Mary Caperton Morton

Prime campsites on the shores of Yellowstone Lake were continuously occupied for 9,500 years, and obsidian mined from dozens of quarries around the park has been found as far away as Wisconsin, Michigan, and Ontario. “Yellowstone was a nexus for trade and culture and is crossed by ancient trails from every direction,” said Shane Doyle, a research scientist at Montana State University (MSU) in Bozeman and a member of the Apsaalooke (Crow) Nation.

When Yellowstone became the world’s first national park on 1 March 1872, Indigenous Peoples, including Bannock, Blackfeet, Crow, Flathead, Sheepeater, Shoshone, and Nez Perce, were still living in and migrating through the area. Tourism campaigns, however, touted Yellowstone as a pristine wilderness untouched by humanity. “The earliest intentions were to make people think that there were no Native Americans in the park and that they were never there,” Doyle said.

One of the myths perpetuated by the park’s second superintendent is that Native Peoples were afraid of the area’s thermal features and avoided the area. But in fact, the hot springs and geysers were revered and used in ceremonies and vision quests, as well as daily life for processing food and trade goods, Doyle said. “Native people believe that Yellowstone is a very powerful and sacred place. They weren’t afraid of it. They had great respect for it, and geology plays an important role in many tribal legends and origin stories.”

Such stories are only recently being shared with park visitors, Doyle said. “We’ve finally seen a breakthrough in the last year in efforts to educate visitors about Native history and culture. I look forward to seeing more signage and a more prominent Native presence throughout the park.”

The Supervolcano Myth

Yellowstone has an impressive volcanic resume—but don’t call it a supervolcano, a colloquial term with no scientific definition. Instead, geoscientists prefer the term Yellowstone caldera system or Yellowstone caldera complex. “I wish the word supervolcano could be banished from the record as it enforces the myth that Yellowstone only produces supereruptions,” said Michael Poland, the current scientist-in-charge of the Yellowstone Volcano Observatory (YVO), the research consortium that monitors the volcano.

“The most common misconception about Yellowstone is that it’s overdue for an eruption. But volcanoes don’t work like that.”In its 2.2-million-year history, the Yellowstone caldera system has erupted catastrophically only three times, while producing many localized lava flows. “Yellowstone is not going to erupt again anytime soon, and when it does, it’s much more likely to be a lava flow than an explosive event,” Poland said. “These lava flows are really impressive. They can be hundreds of feet thick. But they’re not particularly hazardous beyond the immediate area.”

The last supereruption (defined as an event greater than magnitude 8 on the volcano explosivity index) at Yellowstone took place 630,000 years ago. The last lava flow took place 70,000 years ago. But the relative quiescence since the last eruptions doesn’t mean the system is due for an eruption, Poland said.

“The most common misconception about Yellowstone is that it’s overdue for an eruption. But volcanoes don’t work like that,” he said. “They erupt when there is a sufficient supply of eruptable magma in the subsurface and enough pressure to get that magma to the surface, and right now, neither condition exists at Yellowstone.”

Currently, the two stacked magma chambers under Yellowstone are mostly stagnant. “People tend to picture a giant pool of molten magma down there just waiting to erupt, but that’s not the case,” said Jamie Farrell, a seismologist at the University of Utah who runs the seismic monitoring program at Yellowstone.

“We have a lot of confidence that if Yellowstone were gearing up for an eruptive event that we would know about it years in advance. It’s not going to take us by surprise.”Seismic studies that image the interior of Earth indicate that the two magma reservoirs contain between only 5% and 15% molten material. “That tells us the volcanic system is nowhere near primed for an eruption,” Farrell said. “Typically, you need at least 50% melt for it to mobilize and begin moving toward the surface.”

The process of filling a magma chamber with molten material is not a quiet one. “We would expect to see increased seismicity, ground deformation, changes in thermal and gas emissions for decades and perhaps centuries in advance of an eruption,” Poland said. “We have a lot of confidence that if Yellowstone were gearing up for an eruptive event, we would know about it years in advance. It’s not going to take us by surprise.”

Next-Level Neighborhood Watch

Very little of what happens at Yellowstone above or below the ground goes unnoticed; the Yellowstone caldera is one of the best-monitored volcanoes on Earth. Satellites keep an eye on the seasonal cycles of ground deformation, while thermal and gas monitoring networks detect subtle changes in heat and gas outputs.

A map of the overlapping calderas, lava flows, and potential hazards of Yellowstone, including earthquakes and hydrothermal explosion craters. Credit: USGS. Click image for larger version.

Dozens of permanent and hundreds of portable seismic stations spread throughout the park and around its borders keep tabs on Yellowstone’s near-constant quivering, including earthquake swarms, where hundreds of small earthquakes can occur over a period of days to months. These events often inspire sensational headlines that Yellowstone is awakening—but they are not harbingers of catastrophe, Farrell said, as they are usually triggered by water moving underground in the geothermal areas.

The most likely hazards to strike the park on human timescales are not magma related, Farrell said. “The most likely geologic hazard would probably be a hydrothermal explosion.” As mineral-rich groundwater moves through hot springs and geysers, deposits thicken on the walls of the underground passages. Clogs can cause pressure to build up until an explosion occurs, sometimes forming a crater at the surface. “Some of these explosions can be pretty large. They happen annually, mostly in the backcountry, but they have happened in the major geyser basins before.”

Explosions can also occur when groundwater rapidly flashes into steam. “In Yellowstone, there are a dozen or so decent-sized craters, a few hundreds of meters across, from hydrothermal explosion events,” Poland said “If that were to happen today in the front country, it could cause a lot of damage.”

The magnitude 7.3 Madison River Canyon earthquake kicked off a massive landslide that dammed the Madison River in 1959. Credit Mary Caperton Morton

The next most likely hazard to affect park visitors is a large earthquake, Poland said. On 17 August 1959, a magnitude 7.3 earthquake struck the Yellowstone area and kicked off a 73-million-metric-ton landslide that dammed the Madison River. The landslide and resulting flooding killed 28 people, most of whom were camping along the river, and drastically changed the landscape by creating a new lake, Quake Lake.

Today, another “strong earthquake could do a lot of damage to the park and impact visitors, but it’s not going to set off the volcano,” Poland said. “The system doesn’t work like that.”

Yellowstone’s hydrothermal systems, including the Old Faithful geyser, are among the most dynamic geologic elements in the park. Credit: Mary Caperton Morton

However, a big earthquake could affect the hydrothermal systems and perhaps increase or decrease geyser activity, Farrell said. “The thermal areas are very dynamic. There are a lot of old, inactive hydrothermal areas in the park, and we’ve seen new ones form in the past few decades. Old Faithful could shut down tomorrow, which would be a big change to the Yellowstone experience.”

Farrell and his team are hoping to learn more about what factors drive changes to the park’s thermal features by deploying hundreds of battery-powered seismic instruments throughout the geyser basins. “We are hoping to develop hydrothermal monitoring systems, where we use seismometers, GPS stations, thermal and gas monitoring instruments to track changes on short timescales,” he said. The monitoring systems, which are on the YVO’s 10-year plan, may also provide some way of forewarning of impending hydrothermal explosions. “That’s a hazard we still don’t know much about,” Poland said.

What’s Scarier Than Lions and Bisons and Bears? Climate Change, Oh My! The author waits for a herd of bison to pass on the Hellroaring Creek segment of the Black Canyon of the Yellowstone hike. Credit: Mary Caperton Morton

In April, I backpacked through the Black Canyon of the Yellowstone, a 32-kilometer trek known for being the best early-season backpacking trip in the park. In the 3 days we spent on trail, we saw only two day hikers, dodged hundreds of bison and elk, and followed in the frighteningly fresh footsteps of both grizzly bears and mountain lions.

When hiking in bear country, I travel in groups, make noise (I skip the bells and use my voice), carry bear spray, and store all food and scented items away from camp. In hundreds of kilometers of hiking in the Greater Yellowstone Ecosystem, I’ve seen a few bears in distant, peaceful encounters, and I’m sure many more have seen or heard me coming and stepped off the trail to let me pass. Bears have a huge task in feeding themselves with a mostly plant based diet, and I firmly believe that humans are not on their menu—they don’t want to encounter us any more than we want to encounter them.

Fresh tracks left by one of the estimated 150 grizzly bears that live within the boundaries of Yellowstone National Park. Credit: Mary Caperton Morton

Keeping a clean camp and storing food properly high in a tree, up a bear pole, or in an approved bear canister are the best ways to keep bears from associating humans with food rewards. A famous park service saying is “a fed bear is a dead bear”: Sloppy people are far more dangerous to bears than bears are to people. Hiking, camping, and doing fieldwork in grizzly bear country can be stressful, agrees Madison Myers, a volcanologist at MSU in Bozeman, but with proper precautions, “I am honored to share space with them.”

Yellowstone is famous for its long, deep winters, and a few decades ago, I might have needed snowshoes to hike the Black Canyon in early April and may have also been less likely to cross paths with still-hibernating bears. But the spring thaw is coming weeks earlier to Yellowstone, affecting snowpack, streamflow, water availability, vegetation patterns, and bear sleep schedules and stoking landscape-scale wildfires.

In June, a team led by researchers at MSU released a new “Greater Yellowstone Climate Assessment” that found that average temperatures are the warmest they’ve been in the past 800,000 years, and carbon dioxide levels are the highest they’ve been in the past 3.3 million years. Since 1950, average temperatures have increased by 1.3℃, and the report predicts that without drastic measures to reduce carbon dioxide emissions, temperatures could soar by as much as 5.6℃ by the end of the 21st century.

Bison frequently roam on Yellowstone’s roads, often causing traffic jams. Credit: Mary Caperton Morton

Grizzly tracks are formidable, but the human footprint on Yellowstone is large and getting larger. In 2019, more than 4.2 million people visited the park, with visitation expected to soar even higher in 2021. Often portrayed as a vast wilderness, in reality the nearly 9,000-square-kilometer park is crisscrossed by more than 750 kilometers of roads that connect more than 1,500 buildings, including nine hotels and 11 visitor centers and museums.

“On human timescales, I don’t think people will see that much large-scale geologic change in Yellowstone,” said Carol Stein, a geophysicist at the University of Illinois at Chicago. “Yellowstone is a lovely place and will stay lovely for a long time, but climate change is happening before our eyes and quickly altering the landscape. In our lifetimes, I expect climate will be the dominating force of change in Yellowstone.”

Yellowstone, Forever

Ask the average person to imagine the future of Yellowstone, and that person might picture a mushroom cloud looming over a smoking crater. “When people hear I study Yellowstone, they always ask, ‘When is it going to erupt?’ and when I tell them that the chance of an eruption in their lifetime is next to nothing, they’re almost disappointed,” Myers said. On longer timescales, “there is a chance of another eruption on million-year timescales, or it may never erupt again at all.”

“There is a chance of another eruption on million-year timescales, or it may never erupt again at all.”On multimillion-year timescales, as the North American plate continues moving southwest over the Yellowstone hot spot, the plume will migrate to the northeast, toward the thicker crust of the Beartooth Plateau. “When the plume hits the Beartooth Mountains, we don’t know what will happen,” Myers said. “Can volcanism work its way up through the plateau? Or will it somehow flow around the sides? Or will it wait until it pops out the other side near Billings in another 5 million years or so?”

Could another Yellowstone arise in Montana’s largest city in a few million years? Will Billings even be on the map by then? Only geologic time will tell.

Author Information

Mary Caperton Morton (@theblondecoyote), Science Writer

Living in Geologic Time is a series of personal accounts that highlight the past, present, and future of famous landmarks on geologic timescales.

Thousands of satellites are orbiting the Earth and observing conditions in the atmosphere, the oceans, and the land surface. Vast amounts of information are being collected all the time, but raw data needs manipulation before it becomes useful for scientific analysis. Python is a programming language that can be used to process satellite data sets for Earth science research. Earth Observation Using Python: A Practical Programming Guide is a new book recently published in AGU’s Special Publications series. It presents an introduction to basic Python programming that can be used to create functional and effective visualizations from earth observation satellite data sets. We asked the author about her vision for the book and how people can best utilize it.

What is Python and what makes it a useful tool for geoscientists?

Python is a free, easy to learn programming language that has grown in popularity. Compared with Fortran, the first programming language that I learned, Python is especially useful for Earth science research because it has add-on packages that facilitate reading, analyzing, and visualizing satellite observations.

Python is open-source and maintained by a community of coders. It evolves in tandem with new research trends and data sources.There are other programming languages, but in the spirit of “open-science,” I appreciate that Python is open-source and maintained by a community of coders and not a single commercial entity. This means that code can be freely shared between scientists without any expensive commercial licenses. Also, because Python is maintained by the community it is a “living language” that evolves in tandem with new research trends and data sources.

What motivated you to write a programming guide about Python?

Because Python is a general-purpose language, there is already a lot of great content about Python programming on the web. However, there were fewer resources that focused on using Python for Earth-observing satellite datasets. Even as an experienced programmer, it was challenging for me to bridge general code examples online with field specific problems in my research.

I strongly believe in open science and skill sharing, so I began teaching Python workshops to provide a structured way for Earth scientists to learn the Python language that was also relevant to their research. Later, I wrote this book to provide more detail than I can teach in the workshop and to share the content with a wider audience. I also wanted to use the book to showcase some interesting real-world examples of satellite observations using my experience as a researcher for the JPSS and GOES satellite programs.

How would you convince someone new to Python the merits of learning a new programming language?

We live in the “golden age” of satellite data. Python makes these satellite datasets more accessible to scientists across the world.We live in the “golden age” of satellite data and there are also many powerful programming languages that a scientist can use to analyze the data. However, some of these languages are not tailored for the Earth sciences or require a prohibitively expensive software license. Python is both powerful and free, making these (public!) satellite datasets more accessible to scientists across the world.

If you are new to scientific programming, Python is a great language to invest your time in. If you are already familiar with another language, you will find Python is relatively easy to learn and has a great set of packages that may make your workflow easier, providing another programming tool you can use in your work.

Who might find this guide useful?

This book is written for scientists who are hands-on and want to learn about Python for their research using relevant examples. When I was learning Python, I started with an in-person boot camp, then I tried an online course, and then I studied a textbook. Ultimately, what really helped to solidify my knowledge were practical, real-world examples using satellite data. So, I recommend this text to those who prefer working through simple examples that can be translated and applied to the readers area of interest.

How to you suggest readers use this guide?

I based the content of this book on the live classroom workshops that I taught over the past three years. Although these workshops are now captured in book format, I would like this guide to be an active learning experience.

The book is structured so that the readers can progress at their own personal pace.The book is structured so that the readers can progress at their own personal pace and from anywhere in the world. I recommend working through a section each day. Once you learn a new skill, I recommend sharing your knowledge with a colleague or uploading your example to an online code repository, such as GitHub.

What knowledge and skills do you hope readers will develop from using your book?

My hope is that readers will work through the coding examples to improve their general Python coding knowledge, and more importantly, explore and model data, and share what they discover. Just as writers read other authors work, I encourage Earth scientists to study examples of working code in addition to writing their own.

By the end of the book I hope that readers will transfer their new skills to their own research area and then share their code online with other scientists so others can learn from them too! In a world where data are free and abundant, we can all contribute to learning the basic skills and new scientific problem-solving paradigms using the tools that Python offers.

Earth Observation Using Python: A Practical Programming Guide, 2021, ISBN: 978-1-119-60688-8, list price $169.95 (print) AGU members receive 35 percent off all books at Wiley.com. Log in to your AGU member profile to access the discount code.]

―Rebekah B. Esmaili (rebekah@stcnet.com; 0000-0002-3575-8597), Science and Technology Corp, USA

Editor’s Note: It is the policy of AGU Publications to invite the authors or editors of newly published books to write a summary for Eos Editors’ Vox.

Craters are telltale evidence of massive meteorite impacts. But on an eroding planet like Earth, they disappear over time. Scientists now have found a much more subtle calling card of an impact—tiny nodules of glass, forged at high temperatures and pressures—strewn over hundreds of square kilometers in Chile’s Atacama Desert. These centimeter-sized objects, which researchers have dubbed “atacamaites,” were likely formed when an iron-rich meteorite struck Earth roughly 8 million years ago, the team concluded.

An Airborne Journey

Space rocks that enter Earth’s atmosphere—meteors—typically move at several kilometers per second, and they deliver a ferocious blow if they strike the planet. All of that energy can melt terrestrial quartz-containing rocks and launch the resulting molten material high into the atmosphere, where it can resolidify midflight. The resulting nodules of glass often have characteristic aerodynamic shapes reflective of their airborne journey.

Such “impact glasses” are relatively rare, however: Prior to this discovery in Chile, only five geographically distinct groupings of impact glasses were known. “There are shockingly few of them,” said Aaron Cavosie, a planetary scientist at the Space Science and Technology Centre at Curtin University in Perth, Australia, not involved in the research. “They’re special.”

Finding another site of impact glasses is always exciting, added Marc Fries, a curation scientist at NASA Johnson Space Center in Houston also not involved in the research. “It adds to the record of impacts on the planet.”

Searching the Desert

Michael Warner, an electrical engineer at the National Optical-Infrared Astronomy Research Laboratory in La Serena, Chile, has been searching the Atacama Desert for meteorites since 2002. It’s an ideal place to look for space rocks, he said, because they tend to just sit there rather than being washed away or buried by erosion. “The surface hasn’t been altered for about 20 million years.”

“I thought they looked like rat poop.”In 2007, Warner found his first meteorite, a roughly half-kilogram specimen. Five years later, on another trip to the Atacama Desert, Warner and his son found a plethora of small, black objects. They weren’t much to look at, the elder Warner remembered. “I thought they looked like rat poop.” But he picked up some of the centimeter-sized objects nonetheless and mailed six to Jérôme Gattacceca, a geologist at the National Centre for Scientific Research in Aix-en-Provence, France, who had previously helped Warner classify his meteorite finds.

Gattacceca was immediately intrigued. “They looked unusual,” he said. Gattacceca ruled out common basaltic rock, and he concluded that the samples were impact glasses. Their smooth, rounded shapes—including rods, teardrops, and dumbbells—were one giveaway. “You can see that they’ve flown in the atmosphere,” said Gattacceca.

A Trove of Glass

Gattacceca and several of his colleagues have since traveled to the Atacama Desert to collect more. Their fieldwork, which began in 2014, has since revealed more than 23,000 of these atacamaites.

“Atacamaites have no equivalent among the few known terrestrial ejected impact glasses.”Gattacceca and his collaborators analyzed several atacamaites in the laboratory and showed that they’re made largely of terrestrial rock, as expected. But meteoritic material—most notably, iron, nickel, and cobalt—accounts for about 5% by weight of atacamaites, the researchers noted. That’s a significantly larger extraterrestrial contribution than what’s typically found in other impact glasses. “Atacamaites have no equivalent among the few known terrestrial ejected impact glasses,” the team reported in June in Earth and Planetary Science Letters.

On the basis of extraterrestrial material found in atacamaites, Gattacceca and his colleagues surmised that the meteorite that produced these impact glasses was most likely dominated by iron. The impact that created atacamaites occurred roughly 8 million years ago, fission-track dating suggested, but there’s mysteriously no evidence of a crater within the roughly 25-kilometer × 25-kilometer strewn field. It might have eroded away, the researchers suggested, but they’re not giving up the search yet. They’re scouring satellite imagery and are planning future fieldwork in the region. “We’ll go back,” said Gattacceca.

—Katherine Kornei (@KatherineKornei), Science Writer

This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

Los efectos del cambio climático no tienen el mismo impacto en todas las personas: para los grupos vulnerables siempre es peor. Esta discrepancia es evidente incluso cuando estos grupos no son minorías, como es el caso de las mujeres, que forman la mitad de la población mundial. Un nuevo estudio de caso de Brasil muestra que incluso cuando los procesos de formulación de políticas son altamente participativos e involucran a diferentes sectores de la población local, aún limitan la participación de las mujeres.

Un equipo de investigadores ahondó en un proceso participativo sobre la planificación de la mitigación del cambio climático en Piracicaba, una ciudad del interior del estado de São Paulo. La coautora Nara Perobelli, consultora del proyecto Pira no Clima de la organización conservacionista sin fines de lucro Imaflora y el grupo de trabajo de género del Observatorio Climático de Brasil, participó en las reuniones responsables del Plan Participativo para la Adaptación y Mitigación del Cambio Climático en Piracicaba.

De abril a septiembre de 2020, Perobelli siguió 30 eventos, incluidos diálogos, reuniones temáticas específicas, reuniones de grupos de trabajo y talleres. Estos eventos involucraron a cientos de participantes y se llevaron a cabo en línea debido a la actual pandemia de COVID-19.

El estudio revela que a pesar de que las mujeres y personas LGBTQ constituían más del 80% del público en los diálogos participativos, definidos como discusiones de políticas con el objetivo de escuchar a las mujeres, la comunidad LGBTQ y otros grupos minoritizados, fueron invitadas como oradoras o mediadoras en solo la mitad de estas oportunidades. Los principales resultados del estudio son objeto de un cartel que los autores presentarán en la reunión de otoño de la AGU el 8 de diciembre.

Efectos desproporcionados del cambio climático

El problema no es que las mujeres no hablen. Lo hacen, pero los hombres no siempre los escuchan.El problema, según Perobelli, no es que las mujeres no hablen. Lo hacen, pero los hombres no siempre los escucharán. Vio este patrón repetirse una y otra vez en los eventos en los que participó. “Hubo casos de mansplaining e interrupción de hombres en estos procesos. Antes de ser un espacio para hablar, el proceso participativo es, ante todo, un espacio para la escucha “, dijo.

Perobelli vio el mismo patrón con la participación de la comunidad LGBTQ.

La falta de representación en estos diálogos, como lo ve la coautora de Perobelli, Isabel Garcia-Drigo, comienza antes del proceso de planificación en sí. Las metodologías que se utilizan normalmente para la evaluación y el mapeo de riesgos son insuficientes para abordar el amplio y complejo tema de la representación.

“Las evaluaciones de riesgo del cambio climático no están desglosadas por género y merecen un replanteamiento. Y estamos hablando de regiones de São Paulo, el estado más rico de Brasil, en donde ha habido algunos avances institucionales interesantes en términos de participación pública en la formulación de políticas “, dijo Garcia-Drigo, coordinadora de proyectos de clima, suministro agrícola y bosques de Imaflora.

“Las mujeres siempre están al frente en términos de vulnerabilidad, pero no en la toma de decisiones.”La Convención Marco de las Naciones Unidas sobre el Cambio Climático (UNFCC, por sus siglas en inglés) tiene el género como uno de sus temas de discusión. En un informe de 2019, el grupo identificó que los datos desglosados por sexo y género son “las herramientas más eficaces y críticas para identificar impactos diferenciados”. La UNFCCC también recomienda que los países trabajen para reconocer los diferentes efectos del cambio climático en las identidades además del género al recopilar datos y reconstruir evaluaciones de vulnerabilidad.

El género no es una dimensión comúnmente abordada en el debate sobre políticas de cambio climático, pero debería serlo, enfatizaron Perobelli y García-Drigo. “En las zonas rurales, las mujeres tienen un papel importante en el uso del agua y en la agricultura familiar. En las ciudades, se ven más afectadas por problemas como la movilidad urbana, por ejemplo “, explicó García-Drigo. “Siempre están al frente en términos de vulnerabilidad, pero no en la toma de decisiones”.

Los datos de las Naciones Unidas confirman las observaciones de García-Drigo. Según la ONU, el 70% de los más de mil millones de pobres en el mundo son mujeres. En las comunidades más pobres, las mujeres son responsables de buscar agua y leña para proporcionar energía para cocinar y calentarse, y también están muy comprometidas con la agricultura de subsistencia. Teniendo en cuenta que los desastres naturales tienden a afectar más a los pobres, es probable que las mujeres se encuentren entre las poblaciones más afectadas por los efectos del cambio climático.

Inspirar el cambio donde se necesita

Según Myrian Del Vecchio de Lima, profesora de comunicación en la Universidad Federal de Paraná, Brasil, que ha trabajado con la gobernanza del cambio climático, un aspecto interesante que enfatiza el nuevo estudio es cómo los roles de género tradicionales se perpetúan incluso en los procesos participativos en la formulación de políticas.

“Los hombres estuvieron mucho más presentes en las discusiones sobre la adaptación y mitigación del cambio climático que en las de género o desigualdad social, [que estaban] dominadas por las mujeres”, dijo. De Lima, que no participó en la nueva investigación, considera que este tipo de estudio es una herramienta importante para inspirar el cambio donde se necesita.

“El estudio es importante porque este es un debate que todavía falta incluso en entornos más interdisciplinarios en la academia, y mucho menos fuera de ella”, dijo.

—Meghie Rodrigues (@meghier), Escritora de ciencia

This translation by Daniela Navarro-Pérez (@DanJoNavarro) of @GeoLatinas and @Anthnyy was made possible by a partnership with Planeteando. Esta traducción fue posible gracias a una asociación con Planeteando.

Horvath and Lovell [2021] are the first to describe two separate geomagnetic storm events occurring in 2017 in which detected Kelvin-Helmholtz (K-H) waves on the magnetopause were observed to be correlated with surface waves in the hot zone of the outer plasmasphere. The Near-Earth Plasma Sheet (NEPS), activated by the K-H waves, acts as a resonator with eigenfrequencies in the Pc4-5 range, and leads to surface waves in the low-density hot zone of the outer plasmasphere.

Observations confirm the coupling along magnetic field lines through field-aligned currents that link these high-altitude undulations to the auroral region. For one event a complex flow channel structure in the auroral regions was observed that appeared as sub-auroral ion drifts (SAIDs) early in the storm, and as sub-auroral polarization streams (SAPS) and abnormal SAIDs at later times. Observed wave structure embedded within the SAPS appeared to correlate well with the KH waves. The paper demonstrates the complex coupling that occurs over extremely large distances from the magnetopause to the auroral zones.

Citation: Horvath, I., & Lovell, B. C. [2021]. Subauroral flow channel structures and auroral undulations triggered by Kelvin-Helmholtz waves. Journal of Geophysical Research: Space Physics, 126, e2021JA029144. https://doi.org/10.1029/2021JA029144

—Michael P. Hickey, Editor, JGR: Space Physics

In 2019, a team of astronomers caught the first hints of a young exoplanet surrounded by the right stuff to form satellites. Those hints now have been confirmed by high-resolution images that capture light from a potentially moon-forming swirl of dust that surrounds that planet.

The young planetary system, PDS 70, “is the first system where two growing planets, at least one with a circumplanetary disk, have been observed directly,” said Stefano Facchini, an astronomer at the European Southern Observatory and a coauthor of the recent discovery. “The circumplanetary disk around PDS 70 c today is the perfect environment to study the conditions of satellite formation.”

The Testing Grounds

It takes millions of years to form a planetary system from an interstellar cloud of gas and dust. Gravitational instabilities in a cloud will cause it to slowly collapse onto itself until the temperature at the center is hot enough to ignite a protostar. Most of the remaining material falls onto the star, and the remainder flattens out into a disk (called a circumstellar disk) that might, after millions more years, form planets.

“Satellite formation is possible precisely when the accretion rate onto the planet is low, of the order of what we are observing today.”This same process is thought to repeat itself on a smaller scale when planets try to form their own moons (instead of capturing them): After a young planet accumulates enough mass to carve out gaps in the circumstellar disk, dust and gas still surround the growing planet and can flatten out into a smaller disk around it. That circumplanetary disk can then coalesce into one or more satellites. The four Galilean moons of Jupiter are thought to have formed in this way, but the only way to prove that this mechanism forms moons is to catch it in the act.

Enter PDS 70, a star merely 5.4 million years old that is still surrounded by a circumstellar disk. Two gas giant planets that are still accumulating mass have so far been detected as they carve gaps and shape rings within the circumstellar disk.

Upon a closer look at the outer planet PDS 70 c, which is a few times Jupiter’s mass and orbits its protostar slightly farther than Neptune does from the Sun, astronomers detected a faint, fuzzy emission haloing it. They tentatively identified that fuzz as a circumplanetary disk. “The planet has already acquired most of its mass during its past evolution,” Facchini explained. “As for the moons, theoretical models show that satellite formation is possible precisely when the accretion rate onto the planet is low, of the order of what we are observing today.”

The outer of the two young planets in the PDS 70 system (left) is surrounded by a cloud of dust (right) that spans the distance separating the Sun and Earth and is a likely site for exomoon formation. The disk itself is entirely contained within the brightest spot of the image; the fuzzy edges around the planet are noise from the instrument. Credit: ALMA (ESO/NAOJ/NRAO)/Benisty et al., CC BY 4.0

After that first identification 2 years ago, the team pushed to observe this still-forming planet and the satellites it could be growing. With the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the team was able to capture high-resolution images of the entire PDS 70 system at wavelengths favored by planet-forming dust. When combined with previous observations, the images revealed that the dust surrounding PDS 70 c extends one Earth-to-Sun separation (1 astronomical unit) from the planet, about 4 times wider than Saturn’s rings. “Today the circumplanetary disk has a dust mass that is at least three Moon masses,” Facchini said, “but during the remaining lifetime much more dust mass can be acquired by the system,” maybe as much as an Earth mass of material. The team published this discovery in Astrophysical Journal Letters on 22 July.

Up Next: What Moons Are Made Of

“Our work presents a clear detection of a disc in which satellites could be forming,” lead author Myriam Benisty of the University of Grenoble in France and the University of Chile said in a statement. “Our ALMA observations were obtained at such exquisite resolution that we could clearly identify that the disc is associated with the planet and we are able to constrain its size for the first time.”

Long predicted, this seems like the first really robust observation of a circumplanetary disk busy (perhaps) making exomoons…simply fabulous data from ESO https://t.co/TGtPTNjMNl

— Caleb Scharf (@caleb_scharf) July 22, 2021

So far, the team has been able to measure the dust component of the circumstellar and circumplanetary disks. However, there might be 100 or 1,000 times more gas than dust in the disk that hasn’t yet been mapped. The team is currently using ALMA to study how that gas moves throughout the system, Facchini said. With ALMA and also future observatories, the researchers hope to determine the chemical composition of the material that is forming the atmospheres of PDS 70 c, the inner planet PDS 70 b, and any moons that may be growing around them.

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

Roadside ditches are a catchall for water, from both sheets of rain that fall on roads and runoff from lawns or fields. Although ditches are ubiquitous in the landscape, they have the potential to be much more than a storm water conduit. In fact, ditches are human-made lowlands that often act as wetlands, complete with fluctuating water levels and a broad array of vegetation and microbes.

In these human-made landscapes, resident microbes and vegetation have the ability to strip nitrogen out of the entering waters, removing it from the system. In the process, nitrogen removal in ditches can reduce the downstream effects of excess nutrients, such as algal blooms and dead zones.

But how effective are ditches at removing nitrogen? Until now, it was poorly understood.

In a new study, Tatariw et al. compared how ditches—those next to forests, urban areas, and agriculture fields—remove nitrogen and what sorts of microbes live in each locale. They looked at three different watersheds near Mobile Bay in Alabama and sampled 96 different ditches that stretched along paved two-lane roads. Each watershed represented ditches along forested, developed, or agricultural lands.

To characterize the ditches, the team looked at plant biomass, inorganic nitrogen content in water, and soil characteristics. Because microbes are so small, they can’t be identified even using a microscope, so the scientists used 16S rRNA genes to identify and analyze the different microbes in each sample.

Last, the researchers calculated the potential of nitrate removal for each sample by taking the soil samples, adding water, and making a slurry of ditch material. A stable isotope of nitrogen (15-nitrate) was added to the slurries to see how much nitrogen was reduced by the microbes in the sample.

They found that the microbes in ditches had the potential of removing nitrate (NO3–) by upward of 89% on average. Although the soil characteristics between types of ditches were similar, the team notes that specific microbes—classified as Nitrososphaeraceae, Nitrosomonadaceae, Gaiellales, and Myxococcales—were more abundant in urban and agricultural ditches where human activity is prevalent.

Overall, ditches were found to have a nitrogen removal potential similar to many natural ecosystems such as wetlands and rivers. The new research shows that roadside ditches may be important areas for removing nitrogen from the environment. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2020JG006115, 2021)

—Sarah Derouin, Science Writer

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

对石油和天然气工业的环境和社会影响的研究大多集中在这一过程的开始和结束:在哪里开采资源，在哪里提炼和消费资源。然而，很少有人注意到中间基础设施——在美国纵横交错着的巨大管道系统。在一项新研究中，Emanuel等人通过在郡县一级比较天然气管道密度和社会脆弱性，设法正视这一存在于整个大洲的差距。

美国疾病控制与预防中心(Centers for Disease Control and Prevention)设计了一个社会脆弱性指数，用来衡量一个社区在面对自然或人为灾害时的预防、处理和恢复能力。社会脆弱指数高的县将无力应对潜在的管道灾难。研究人员发现，在美国，社会脆弱程度越高的县，管道密度越高，而社会脆弱程度越低的县，管道密度越低。管道密度最高的县的相关性更强。

作者指出了与这一庞大的基础设施网络的建设和运营有关的环境损害的不公平分配所产生的政策影响。管道带来的负担——包括噪音、降低的房地产价值和土地使用选择、泄漏或爆炸的风险以及文化损害——不成比例地落在最不具备处理能力的社区身上。

管道通常位于农村地区而非城市地区。尽管农村地区的人口密度较低，很多时候被认为“风险较低”，但农村路线并不会分散风险；作者说，它们呈现出一系列不同的风险。此外，科学家们强调，扎根于农村地区的土著居民与特定的景观和水道有着深厚的文化联系，这些景观和水道越来越多地受到管道建设和运营的影响，如果土地遭到破坏，他们的文化和社区可能也会受损害。农村应急响应系统用来处理大型灾害的资源较少。此外，当地对化石燃料基础设施的冲突可能会迅速将农村社区撕裂，导致大规模搬迁，在短短几年内将农村社区转变为工业景观。

科学家们建议，未来的项目要进行更严格的环境公正评估，纳入以文化和社区为重点的研究和地方视角。他们呼吁其他科学家与边缘化社区合作，识别和量化可能被管道项目背后的强大力量忽视或忽略的影响。最后，他们提醒决策者考虑现有石油和天然气工业基础设施的累积风险，包括气候变化带来的问题，这些问题也往往会影响到最脆弱的群体。 (GeoHealth, https://doi.org/10.1029/2021GH000442, 2021)

-科学作家Elizabeth Thompson

This translation was made by Wiley. 本文翻译由Wiley提供。

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Modern weather forecasts and climate studies rely heavily on computer simulations implementing physical models. These models need to make cohesive large-scale predictions but also include enough small-scale detail to be relevant and actionable. Given the enormous physical complexity of weather systems and the climate, realistic stochastic simulation of hydroenvironmental events in space and time, such as rainfall, is a significant challenge.

A statistical approach is a natural alternative to describe the huge variability of weather systems and the climate. Statistical models are easier to use and do not require massive computational resources and thus provide scientists and decisionmakers with operational, easy-to-use tools to study pressing climate-related problems. Nonetheless, statistical models often make simplifying assumptions.

An animation simulating cyclonic evolution. Credit: Papalexiou et al., 2021, https://doi.org/10.1029/2020WR029466

Although these assumptions can make the modeling task more tractable, they also lead to additional divergence from the physical systems they are intended to represent. Papalexiou et al. describe improvements to the so-called Complete Stochastic Modelling Solution (CoSMoS) framework that introduce significantly increased generality for a wide range of hydroenvironmental simulations.

One important addition is support for spatially varying velocity fields. These velocity fields govern the movement of packets of fluid, such as air or water, across the simulated region. Such gradients are extremely common in nature; the expansion of air as it warms, for example, creates an outwardly diverging velocity pattern. Similarly, the rotation of a hurricane or tornado requires a velocity field that curves in space.

The authors also describe the handling of anisotropy, in which the properties of the physical process can vary with not just distance from a reference point but also direction. By combining anisotropy with spatially varying velocity fields, a simulation can reproduce complex meteorological phenomena, such as storms or the rotating and spiraling structure of a hurricane.

After introducing these advancements, the authors demonstrate their potential through a series of numerical experiments. These simulations illustrate the wide variety of fluid structures and evolution patterns that such a platform can deliver. Nevertheless, challenges remain, including the high computational costs of simulating large structures at high resolution and the need for additional model development with the aim of global-scale simulations. (Water Resources Research, https://doi.org/10.1029/2020WR029466, 2021)

—Morgan Rehnberg, Science Writer