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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

In recent years, heat waves have broken long-standing records by large margins. In spring 2020, Siberia saw exceptional temperatures, and Europe experienced an extreme heat wave in 2003 that killed more than 70,000 people. Now a new study published in Nature Climate Change has found that the probability of extreme record-shattering events is increasing at an alarming rate. These events are unprecedented in the observational record and nearly impossible without climate change. The researchers warned that many places in the world have not yet seen anything close to the intensity of heat waves now possible but should expect them in the coming decades.

Sudden Record-Shattering Events

As the climate warms, you would expect heat waves to break previous records, but not necessarily by large margins. But when Erich Fischer at the Institute for Atmospheric and Climate Science at ETH Zürich in Switzerland and his colleagues looked at large climate model ensembles, they found that simulated events in the near future broke historic records by very large margins. Somewhat surprisingly, the simulations often did not show the intensity of heat waves steadily increasing. Instead, the simulations showed stagnant decades with unbroken or marginally broken records, followed by a sudden record-shattering event.

Image of the Pacific Northwest’s heat forecast on 25 June 2021. Credit: Felton Davis, CC BY 2.0

For example, a heat wave over central North America simulated by the models hit temperatures 18°C higher than the summer mean temperature for 1986–2005. The hottest week of the simulated event broke previous average weekly temperature highs in the simulation by more than 5 standard deviations, smashing records by massive margins. That simulated event is also remarkably similar to the extreme heat event in June that swept throughout the Pacific Northwest of the United States and Canada. During that heat wave, temperature anomalies were 16°C–20°C higher than normal maximum temperatures for the time of year, according to a new study produced by Sarah Kew and colleagues for the World Weather Attribution.

Kew, who is at the Royal Netherlands Meteorological Institute and was not involved in the research with Fischer and colleagues, said that the Nature Climate Change paper is very well timed given recent heat events (which occurred after the paper was written). She added that it is “really uncanny” how similar the simulated central North America event is to the Pacific Northwest heat wave. “[The authors] said that this kind of thing can happen in the near future; well, it just did happen. It acts as a very strong warning of what we can expect,” said Kew.

“The odds that a record-shattering heat event occurs somewhere in the northern extratropics is large and currently rapidly increasing.”In high-emissions scenarios, weeklong heat extremes that break records by 3 or more standard deviations are 2–7 times and 3–21 times more probable in 2021–2050 and 2051–2080, respectively, compared with the past 3 decades, the researchers found. Their analysis suggested that an event as extreme as the one simulated over central North America is expected to occur once every 2 decades in the northern midlatitudes after 2050. Overall, record-shattering events—those that break records by 3 or more standard deviations—are expected to occur about every 6–37 years somewhere in the northern midlatitudes.

“Record-shattering heat extremes regularly occur in large ensemble simulations,” Fischer said. “While their probability is small for a specific location, the odds that an event occurs somewhere in the northern extratropics is large and currently rapidly increasing.” He warned that places that have not seen recent increases in heat wave intensity, such as the central and eastern United States, are particularly prone to such events and should expect to see new heat records in the coming decades. He argued that such events need to be taken seriously because their impacts tend to be largest when such temperature extremes first occur because of a lack of adaptation and preparedness.

“It is a clear message to cut emissions.”The simulations showed that these record-shattering events are not caused by new climate mechanisms. Instead, there are extreme variations of common heat wave drivers in the months before, such as an unusually warm spring, low rainfall, low soil moisture, and reduced evaporative cooling. This scenario looks exactly like what led to the recent Pacific Northwest heat wave, according to Kew. She cautioned, however, that further investigation is needed before that can be said for certain.

What is more, Fischer told Eos that the probability of record-shattering heat events depends on the warming rate and not on the level of warming. “If we were to stabilize temperatures at 1.5°, 2°, or 2.5°C, their probability would quickly decline again after a few decades,” he explained.

“It is a clear message to cut emissions,” Kew said.

—Michael Allen (michael_h_allen@hotmail.com), Science Writer

The Great Unconformity remains one of the most alluring mysteries in the Earth sciences. Widespread across North America and present in other parts of the world, the knife-sharp contact between Precambrian crystalline rocks and overlying Phanerozoic sediments can represent a billion years (a quarter of Earth’s history) of missing time.

Precisely because of this missing record, the formation age and mechanism of the Great Unconformity have proven elusive. Formation of the Great Unconformity has been linked to all major tectonic, climatic, and biologic events of the Late Proterozoic – Early Paleozoic, including the assembly and break-up of Rodinia, the Snowball Earth glaciation, and the Cambrian explosion of life.

Thermochronology records the cooling of rocks as they are exhumed to the surface of the Earth and thereby provides one of the few direct proxies for erosion events at geological timescales. Applying thermochronology in “deep time” is challenging, however, because small differences in the kinetics that define how daughter products are retained between the different crystals analyzed can lead to strongly varying ages.

Sturrock et al. [2021] leverage these differences, using apatite (U-Th)/He thermochronology and quantitative thermal-history modeling to constrain the thermal and erosional history of a large tract of the Central Canadian Shield. They convincingly show that the Great Unconformity there formed after 650 million years and link its formation to kilometer-scale erosion in response to mantle-plume related uplift.

Previous work, in part by the same group, has shown that erosion leading to formation of the Great Unconformity in other parts of North America (Wyoming, the Colorado Front Range and the Ozarks) is substantially older, between approximately 850 and 700 million years ago. Thus, there may not be one but several Great Unconformities. This study adds to a growing body of work refuting hypotheses that have suggested that the Great Unconformity occurred in a single worldwide event and was linked to major Earth crises, such as the Snowball Earth glaciation.

Citation: Sturrock, C. P., Flowers, R. M., & Macdonald, F. A. [2021]. The late Great Unconformity of the central Canadian Shield. Geochemistry, Geophysics, Geosystems, 22, e2020GC009567. https://doi.org/10.1029/2020GC009567

—Peter van der Beek, Editor, Geochemistry, Geophysics, Geosystems

Santorini is a collection of five islands about 200 kilometers southeast of the Greek mainland. Credit: NASA/GSFC/METI/ERSDAC/JAROS

For thousands of years, the Greek volcano Santorini has blasted, bubbled, and burned in the Aegean Sea. Now scientists suspect that the volcano’s fiery bursts are the cause of rising and falling sea levels. The findings reveal a novel connection between the planet’s molten innards and its climate.

Sea levels retreat when the planet grows large ice sheets and glaciers; ice ages have much lower sea levels than interglacial periods.

Researchers from the United Kingdom and Sweden found that these lower sea levels tend to disrupt Santorini’s volcanic slumber. During the past 360,000 years, the volcano, officially known as Thira and historically known as Thera, has erupted more than 200 times. All but three of those eruptions happened during or just following periods of low sea levels.

Since most volcanos on Earth sit within or near oceans, Santorini’s tale could apply to other volcanos around the world.

Santorini’s Cliffs The cliffs on Santorini reveal layers of whitish ash deposits from past volcanic eruptions. The largest white layer in the middle distance is Santorini’s Vourvoulos eruption from 126,000 years ago. Credit: Ralf Gertisser/Keele University

Santorini has had a violent past—explosive eruptions have shattered the volcano into slivers of islands.

The most recent explosive eruption, in the 1600s BCE, sent 100 cubic kilometers of material into the air, 4 times that of the 1883 eruption of Krakatoa. The volcano’s caldera collapsed into the sea and flooded, leaving an 11-kilometer-wide crater. (The cataclysm may have inspired Plato’s story of Atlantis, too.)

Over the past 50 years, geologists discovered mounting evidence that the comings and goings of ice sheets revved up volcanos in Iceland, the western United States, France, Germany, and Chile. The ice sheets bore down on Earth’s crust, but when they melted away, the crust decompressed and fractured. Magma shot up the cracks and fueled eruptions.

Sea level, the new paper argues, has the same effect on Earth’s crust. “The only thing that’s different is in one case you have ice, and in the other case you have water,” said Earth scientist Chris Satow from Oxford Brookes University, who led the research.

But finding evidence of sea level’s effect on volcanos has been much harder—until now. A quirk of Santorini’s landscape gave scientists a unique chance to connect the pieces.

Millions of tourists flock to the volcano’s cliffs overlooking the turquoise bay annually, and Satow and his team did the same—but to sample layers of volcanic ash. Eruptions leave unique chemical fingerprints of iron, silica, potassium, sodium, and other elements buried in ash layers. “Not many other volcanoes have got this amazing record on display for us to see and investigate,” said Satow.

The researchers measured the chemical fingerprints of each ash layer and matched them with layers in marine sediments. Crucially, the marine sediments also contained records of sea level rise and fall over time.

Satow and eight others published the research in the journal Nature Geoscience today.

Stifled By the Sea A computer model of Santorini showed that reducing sea levels to 40 meters below present-day levels changes the amount of tensile stress in the roof of the volcano’s magma chamber, which sits just 4 kilometers under the surface. Because there is less water pushing down on Earth’s crust, the crust decompresses and allows fractures to form. As sea levels continue to decrease down to 70 to 80 meters below present-day levels, the crust pulls apart more and allows fractures to reach the surface and feed eruptions. Credit: Oxford Brookes University

The results could explain recent behavior at Santorini. The volcano threatened to erupt as recently as 2011–2012 when new magma flooded the volcano’s shallow magma chamber. “The fact that an eruption did not happen may be due to the sea levels being high,” Satow said.

But major eruptions can still happen; Santorini is one of the world’s Decade Volcanoes, sites identified in light of their history of large, destructive eruptions and proximity to densely populated areas. “The large volumes of magma involved [in explosive eruptions] could by themselves create the required fractures in the crust, even without the help of low sea levels,” Satow said. The massive event that took place in the 1600s BCE, nicknamed the Minoan eruption after the region’s distinct Bronze Age civilization, was one of three eruptions that blew during periods of high sea levels.

Climate change is melting ice sheets and boosting sea levels, but it’s too early to know how that could affect volcanic activity. A study on the volcanic Caribbean island of Montserrat, for instance, proposed that rapid sea level rise could amp up volcanic activity, the opposite effect seen at Santorini.

“We need more of these detailed and comprehensive studies to get a complete picture,” said Julie Belo, a scientist at the GEOMAR Helmholtz Centre for Ocean Research Kiel who did not participate in the work.

Next, Satow hopes to investigate greenhouse gas emissions from volcanos. “It would be really interesting to know if the amount of carbon dioxide that volcanoes worldwide produce is also related to sea level change,” Satow said.

—Jenessa Duncombe (@jrdscience), Staff Writer

Kīlauea in Hawaii is the best-monitored volcano in the world. The 2018 eruption was the largest in some 200 years, providing researchers with a plethora of new data to understand the volcano’s plumbing and behavior. Two new studies dig into data on volcanic tremor and deformation to better characterize the events leading up to and following the 2018 eruption.

In one study, Soubestre et al. used data from a permanent seismic network and tiltmeter located at Kīlauea’s summit and derived models of tremor source processes to examine how volcanic tremors related to the disappearance of a lava lake and subsidence in Halema‘uma‘u Crater at the beginning and throughout the 2018 eruption. Here the authors used a seismic network covariance matrix approach to enhance coherent signals and cut out noise to detect and locate the volcanic tremor sources.

The team identified three previously unidentified tremor sources, including long-period tremor during the period preceding the eruption associated with radiation from a shallow hydrothermal system on the southwest flank of Halema‘uma‘u Crater. The team picked up on two sets of gliding tremor in early and late May. Models show that the first set was linked to the intrusion of a rock piston into the hydrothermal system and the second was linked to changes in the gas content of magma within a dike below the crater affected by a dozen collapse events.

The second study focused on the period following the 2018 eruption. Here Wang et al. used GPS and interferometric synthetic aperture radar data to examine deformation around the caldera associated with the volcano’s known reservoirs—the shallow Halema‘uma‘u reservoir (HMM) and the deeper South Caldera reservoir (SC)—after the eruption ended in August of 2018. They documented inflation on the northwestern side of the caldera and deflation on the southeastern side of the caldera, indicating that the summit magma chambers are hydraulically distinct. The concurrent East Rift Zone (ERZ) inflation indicated dynamic magma transfer between the summit and the ERZ.

The authors presented a new physics-based model that uses differential equations to describe reservoir pressure and magma flux between the volcano’s reservoirs to simulate potential magmatic pathways of connectivity between the reservoirs and the ERZ. They used a dynamic inversion of the postcollapse GPS time series of surface displacement to estimate the conductivity of potential magmatic pathways.

The team found that the primary connective pathway in the postcollapse period that best fits the GPS data is a shallow connection between the HMM and the ERZ. The study doesn’t rule out a direct pathway between the SC and ERZ reservoirs but suggests that if it exists, it was significantly less active over the study period.

Together, these studies help to create an increasingly clear picture of the plumbing and processes governing Kīlauea’s activity in 2018. (Journal of Geophysical Research: Solid Earth, https://doi.org/10.1029/2020JB021572 and https://doi.org/10.1029/2021JB021803, 2021)

—Kate Wheeling, Science Writer

On 15 January 2020, when Brazilian scientists, navy officers, and politicians celebrated the inauguration of the new Comandante Ferraz Antarctic Station in Antarctica, it was like closing a painful chapter in Brazil’s history on the continent.

Almost 8 years earlier, in February 2012, the research facility was destroyed by a fire that claimed the lives of two navy lieutenants, Carlos Alberto Figueiredo and Roberto dos Santos. Located at Admiralty Bay on King George Island, the facility had been operational since 1984 and housed researchers working with PROANTAR (Programa Antártico Brasileiro, the Brazilian Antarctic Program). Caught by surprise by the fire, the country received the news with shock.

The following year, the Brazil Institute of Architects and the Brazilian Navy organized a contest to choose the project for the building that would replace the incinerated station.

The project chosen from more than a hundred proposals from all over the world came from Estúdio 41, a Brazilian architectural office based in Curitiba, the capital of Paraná State. “We put together a multidisciplinary team of about 15 experts in several areas, from wind resistance to geotechnics to thermal insulation, to help us think of how to respond to the harsh environmental conditions in Antarctica. As some of the competing offices had already constructed other research facilities in the continent, we knew winning would be a tough call. So getting it was really exciting,” said architect Emerson Vidigal, a member of Estúdio 41’s team.

The team spent 2 years—from 2013 to 2015—working on the project before China National Electronics Import & Export Corporation, a Chinese construction company, started building the station. “We spent a year on research, looking at similar buildings in Antarctica, and we were lucky to have been able to learn in detail from the Indian research station Bharati. Talking to the engineers of Kaefer, the German construction company that put Bharati together, gave us a deeper understanding of what we were facing. Our partners from the Portuguese engineering office AfaConsult were also crucial in the process, as it was much more an engineering challenge than an architectural one,” Vidigal added.

Bigger and Better

At 4,500 square meters, the new research facility has almost twice the area of the old station and can house 64 people. The steel structure contains an exterior of polyurethane and an insulating interior of mineral wool. “Between the external and internal layers there is a 60-centimeter buffer for temperature transition with air at 10°C on average, which helps save energy for heating,” said Vidigal.

The new Comandante Ferraz station took almost 5 years to construct. Credit: Estúdio 41

As the station’s assembly had to be made during the austral summer, when ships can reach Admiralty Bay, logistics to transport construction machinery, workers, and preassembled structures had to be carefully planned. Almost 5 years and roughly $100 million later, the station was ready.

To glaciologist Jefferson Simões, a researcher at the Federal University of Rio Grande do Sul and vice-president of the international Scientific Committee on Antarctic Research, the investment has been worth the time and effort. “Snow and frozen soil would accumulate in front of doorsteps of the old structure, sometimes making it difficult to get in and out. It is very good that the new building is elevated from the soil so the wind can blow snow away underneath,” he said.

Five of Comandante Ferraz’s 17 planned laboratories (those focused on microbiology, molecular biology, chemistry, microscopy, and common use) are ready. These spaces are equipped with instruments that range from DNA readers to ultrafreezers and water purifiers.

Wim Degrave, coordinator of FioAntar (a research project from the Oswaldo Cruz Foundation that looks for Antarctic pathogens that could threaten human, animal, and environmental health), was at the station in late 2019 to assemble the microbiology laboratory. For him, the new station will enable a significant upgrade for research.

“Usually, we had to process soil, water, plant, lichen, and other samples at a research vessel, freeze them, and wait until the ship was back in Rio de Janeiro many months later to start doing research. This isn’t ideal, since some less stable microorganisms such as viruses can deteriorate. Now we’ll be able to isolate and analyze fresh samples at the station. Not only the quality of research will be better, but it will also be possible to work the whole year in a continuum between sampling and analysis, gaining a lot of time,” he explained.

Even research groups who will not work directly at Comandante Ferraz will benefit from it. “This station is a source of pride for Brazil and its science,” said paleontologist Alexander Kellner, coordinator of Brazil’s PaleoAntar project, which conducts paleontological research in Antarctica. Kellner’s team often goes to James Ross Island, southeast of the Antarctic Peninsula, to look for frozen fossils. “An icebreaker would be a great addition to the new station,” he added. “We would be able to do research in the whole continent.”

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Credit: Estúdio 41

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Credit: Estúdio 41

A Strategic Place

One aspect on which most researchers agree is that a research station in Antarctica is strategic in geopolitical, as well as scientific, terms. “Only the countries that are doing research down there will have a say in the future of the continent,” Simões emphasized.

“A small fraction of the billion-dollar fund the congress is trying to approve to finance political campaigns would do a great good for Brazilian research.”“But a lot of it will depend on funding for research projects, which are quite scarce in Brazil now,” he added.

To him, research in the Antarctic is far from being a luxury. Many projects focus on climate change, air pollution, the carbon cycle, and myriad other studies that directly affect life on Earth, as well as policy. For instance, Simões said, “by looking at some ice cores a few years back, we could clearly detect uranium pollution from mining in Australia in recent decades, as well as arsenic due to copper mining in Chile.”

Simões said Brazil’s research planning in Antarctica is being restructured. As all projects were halted during the pandemic, scientists are seeking resources that stretch beyond 2022. “We don’t have a perspective for funding after that yet. The research station cannot become a white elephant. If the government granted us just a million dollars a year, we’d be able to perform miracles,” Simões said.

“A small fraction of the billion-dollar fund the congress is trying to approve to finance political campaigns (the electoral fund) would do a great good for Brazilian research,” Kellner added.

—Meghie Rodrigues (@meghier), Science Writer

The Mesozoic, which stretched from about 252 million to 66 million years ago, was a pivotal period in Earth’s history. In addition to being the age of the dinosaurs, it was when the supercontinent Pangaea began to separate into the fragmented continents we’re familiar with today. Together with elevated levels of carbon dioxide and the brightening Sun, tectonic changes influenced the global climate, producing warm and humid greenhouse conditions. A detailed understanding of the factors that drove Mesozoic climate trends will not only provide insight into Earth’s history but also help scientists study the consequences of human-caused warming of our planet.

One approach to investigating past climates is using numerical models. In a new study, Landwehrs et al. performed an ensemble of climate simulations covering a period from 255 million to 60 million years ago in 5-million-year time steps. They adjusted specific parameters in different runs to dissect the sensitivity of past climates to paleogeography, atmospheric carbon dioxide levels, sea level, vegetation patterns, the Sun’s energy output, and variations in Earth’s orbit.

The authors found that global mean temperatures during the Mesozoic were generally higher than preindustrial values. They also observed a warming trend, driven by increasing solar luminosity and rising sea levels. Ocean areas typically reflect less solar radiation than land; accordingly, the researchers found that higher sea levels and flooding of continental areas coincided with warmer global mean temperatures. Concurrent with this general trend, fluctuations in atmospheric carbon dioxide produced warm and cool anomalies in global mean temperature. The authors note that this finding does not mean that human-induced global warming should be ignored; modern climate change is happening much faster than changes in Earth’s history.

The ensemble of climate simulations provides insight into other aspects of long-term Mesozoic climate change as well. Overall, the authors identified a transition from a strongly seasonal and arid Pangaean climate to a more balanced and humid climate. To aid additional analyses of Mesozoic climate trends, the authors shared their model data online. (Paleoceanography and Paleoclimatology, https://doi.org/10.1029/2020PA004134, 2021)

—Jack Lee, Science Writer

In the summer of 2020, deadly floods ravaged Africa, affecting nearly a million people and killing hundreds. However, the physical causes of floods across the continent’s diverse climate and terrain are gravely understudied. Lacking a broad network of water gauges, researchers have focused primarily on specific countries or single bodies of water. “The large extension of ungauged areas [has prevented] significant studies [from being conducted both] quantitatively and qualitatively,” said Mohamed El Mehdi Saidi of Cadi Ayyad University in Morocco.

That has now changed, thanks to a 2-year project by an international team to curate the most complete hydrological data set for the African continent to date. This massive compilation combines on-the-ground and remote sensing measurements covering nearly 400 stream gauges and more than 11,000 flood events spanning at least 3 decades. The team’s analysis, the first continent-wide study of flood drivers in Africa, suggested that the largest yearly floods are more strongly linked to regions’ annual peaks in soil moisture than to annual peaks in precipitation. The findings, the first of their kind, were published in June in Water Resources Research.

An 11,000-Piece Puzzle

Other research teams have conducted several continent-wide studies of flood drivers across the United States, Europe, and Australia. Higher data coverage of stream flows and flooding patterns across these landmasses has led to a stronger understanding of when and why damaging floods occur. These continents, however, differ drastically from Africa climatically and geographically, leading scientists to suspect that the triggers of African floods are unique.

Africa’s largely arid climate, with the Sahara covering 25% of the landmass, is part of that equation. “You additionally have this ability to study a climate largely free of snow, which is a complicating factor when studying floods,” said infrastructure engineer Conrad Wasko of the University of Melbourne in Australia who was not involved in the study. With deadly floods becoming increasingly frequent in Africa as climate change worsens, hydrologists felt compelled to improve their data collection across the continent’s widely varying river basins.

This map shows the distribution of measurement stations across Africa. Note the sparseness of data in the central and northeastern regions of the continent. Credit: Tramblay et al., 2021, https://doi.org/10.5194/essd-13-1547-2021

The team’s African Database of Hydrometric Indices (ADHI), published in Earth System Science Data, includes hydrological parameters from watersheds across Africa spanning 33 years on average. Given the sparseness of data across the continent, the team took laborious steps to ensure that the records from different sources were of similar quality. “The most important thing was to manually and visually check each [measurement] independently,” said Yves Tramblay, a hydrologist at the French National Research Institute for Sustainable Development and lead author of the study.

For regions lacking in ground observations, the scientists incorporated Climate Hazards group Infrared Precipitation with Stations (CHIRPS), a series of remote sensing estimates from a hybrid satellite and ground data set, to obtain a homogeneous average of precipitation across all of Africa. They validated these measurements with gauged data when possible. The team’s thorough approach impressed Wasko: “Within engineering, we have a predisposition to collect [on-the-ground] data. New technologies, like remote sensing, are becoming essential to understanding hydrology in remote areas,” he said.

A New Flood Driver Takes the Stage

The ADHI data set allowed the team to compare the timing of several parameters relevant to floods. To determine which ones aligned most strongly with the largest floods each season, they isolated the dates when floods occurred and rigorously compared them to the timing of heavy rainfall and soil moisture conditions using directional statistics—a method that accounts for the direction data follow (in this case, the timing). The analysis revealed that high soil moisture levels showed a stronger correlation to the onset of flooding than to other parameters, most notably rainfall.

“Floods are always caused by precipitation. But the difference in soil moisture conditions before a flood event can strongly modulate its magnitude.”When ground already contains a lot of water, heavy rainfall mostly runs off the surface rather than absorbing into soils—greatly increasing the chances that even modest precipitation will create floods. “It was kind of surprising because we always thought that soil moisture in arid catchments was not a strong driver, but we find that overall it’s still a valuable one,” Tramblay said. “A common assumption is that floods are driven by extreme precipitation events. That’s true: Floods are always caused by precipitation. But the difference in soil moisture conditions before a flood event can strongly modulate its magnitude.”

The new approach invites further research on floods across Africa, Tramblay noted. The team plans to continue conducting targeted studies across many sites to “get a much clearer picture of the differences [in flood drivers] at a regional scale,” he said.

Tramblay also hopes the work will help future scientists and emergency planners across Africa prepare for each year’s flood season by having a better grasp of whether a region might be particularly susceptible. “[This is] an incentive to not look only at extreme rainfall when you’re doing flood projections, but to look at other land surface variables, including soil moisture, vegetation coverage, and change in land use,” said Tramblay. “There’s more recognition that if we’re going to be forecasting floods and designing infrastructure [to mitigate them], it’s not just rainfall we need to be thinking about, but all the other factors that affect flooding.”

—Ellis Avallone (@ellantonia_), Science Writer

Each year, millions of tourists visit geysers around the world, marveling at the jets of water spouting high into the air from subterranean reservoirs. Fascination with these rare features is nothing new, of course: Written records of their occurrence date back to the 13th century at least, and for more than 2 centuries, scientists have been improving our understanding of Earth’s geysers.

The English word geyser originates from geysir, a name given by Icelanders in the 17th century to intermittently discharging hot springs. The name descends from the verb gjósa, which means to gush or erupt. Natural geysers are rare—fewer than a thousand exist today worldwide, and only a handful of fossil examples are known from the geological record. About half of Earth’s geysers are located in Yellowstone National Park in the United States. Other large geyser fields include the Valley of Geysers in the Kamchatka Peninsula of Russia, El Tatio in Chile, and Geyser Flat at Te Puia, Rotorua, in New Zealand.

In 1846, French mineralogist Alfred Des Cloizeaux and German chemist Robert Wilhelm Bunsen formulated an early model to explain geyser eruptions based on field measurements of temperature, chemistry, and circulation and eruption patterns at Geysir in Iceland. Since then, scientific knowledge of geysers has advanced significantly [Hurwitz and Manga, 2017], providing valuable insights into volcanic processes, the origin and environmental limits of life on Earth (and potentially elsewhere, including on Mars), and similar geysers on icy outer solar system satellites. Demonstrating these connections, geologist and planetary scientist Susan Kieffer wrote the following in a perspective on her research career:

“[M]y initial idea of studying Old Faithful geyser as a volcanic analog [sic] led me to work not only on the dynamics of eruption of Mount St. Helens in 1980 but also on geysers erupting on Io (a fiery satellite of Jupiter), Triton (a frigid satellite of Neptune), and Enceladus (an active satellite of Saturn).”

Continuing research into the inner workings of geysers will help us further understand and protect these natural wonders and will reveal additional insights about volcanism on and off Earth.

Like Volcanoes, but More Accessible

Similar to volcanoes, geysers are transient features with periods of activity and dormancy. Geyser eruption patterns can change following large earthquakes, shifts in climate, and variations in the geometry of their conduits and subsurface reservoirs. Eruption processes of geysers, which can be driven by geothermal heating and the formation of vapor bubbles, are also akin to those operating in volcanoes.

Eruption processes of geysers, which can be driven by geothermal heating and the formation of vapor bubbles, are akin to those operating in volcanoes.The model developed by Des Cloizeaux and Bunsen showed that as water rises toward the surface and pressure decreases, boiling forms bubbles. The liquid water containing the bubbles further lowers the density and pressure of the mixture. Decreasing pressure similarly causes changes in magma that underpin key volcanic processes, such as melt generation in the mantle and the formation of bubbles in magma that drive eruptions.

Because geysers have smaller eruptions and erupt more frequently than volcanoes, they provide useful natural laboratories to study eruption processes and test new monitoring technologies. Volcanic eruptions are sometimes preceded by magma movement that is difficult to monitor because of the large spatial scales and long timescales involved. In contrast, measurements of fluid movement, for example, can be made relatively easily through many geyser eruption cycles, providing data that can be used to improve the interpretation of volcanic phenomena. Measurements and video observations can also be collected within the conduits of active geysers—a feat that is impossible at active volcanoes.

An array of instruments (foreground) measures seismic tremor around geysers at El Tatio in Chile. Credit: Shaul Hurwitz, U.S. Geological Survey

Signals such as seismic tremor—sustained ground vibrations that are common prior to and during volcanic and geyser eruptions—can be very informative for monitoring subsurface processes at active volcanoes and geysers. Tremor in volcanoes can last for days, weeks, or even longer leading up to volcanic eruptions [Chouet and Matoza, 2013]. Tremor may be caused by degassing of magma and by the movement of fluids within a volcanic edifice. However, identifying fluid types (gas, liquid water, magma) and the processes responsible for episodes of tremor is challenging because of the geometric complexities and sizes of volcanic systems.

Seismometers deployed around the iconic Old Faithful and Lone Star geysers in Yellowstone have detected tremor caused by continuous bursts of rising steam bubbles, analogous to bubbles forming and bursting in a teakettle. Thus, by analogy, such measurements of tremor in geyser systems can help elucidate processes that generate volcanic tremor.

Tracking tremor signals in time and space using dense arrays of seismometers also has illuminated the subsurface structure of volcanoes and geysers [Eibl et al., 2021; Wu et al., 2019]. The locations of tremor sources around Strokkur Geyser in Iceland, and Old Faithful, Lone Star, and Steamboat in Yellowstone, for example, indicate that these geysers’ reservoirs are not located directly beneath their vents. Tilting of the ground surface around Lone Star Geyser and a geyser at El Tatio, as well as video observations in the conduits of geysers in Kamchatka, also indicate reservoirs that are not aligned below the geysers’ vents. This type of reservoir, in which liquid and steam bubbles accumulate and pressure builds prior to an eruption, is called a bubble trap and might be a common feature of many geysers [Eibl et al., 2021].

Carolina Muñoz-Saez inserts pressure and temperature sensors into a geyser conduit at El Tatio in northern Chile. Seismometers that measured seismic tremor throughout many eruption cycles are visible in the background. These experiments were conducted in coordination with the communities of Caspana and Toconce. Credit: Max Rudolph, University of California, Davis

Laboratory experiments of geysers have shown how heat and mass transfer between laterally offset reservoirs and conduits control eruption patterns [Rudolph et al., 2018]. Geophysical imaging has similarly revealed that although most volcanic vents are located directly above their magma reservoirs, many reservoirs are laterally offset from their associated volcanic edifices [Lerner et al., 2020].

A striking example of an offset magma reservoir was highlighted in a 1968 study of the Great Eruption of 1912 in Alaska [Curtis, 1968], in which magma erupted from Novarupta volcano, but collapse occurred some 10 kilometers away at Mount Katmai, where most of the magma that erupted at Novarupta had been stored. Mapping of such laterally offset magma storage systems, as well as detailed physical knowledge of how they work as gleaned from studies of and experiments with geysers, may help scientists design better volcano monitoring networks.

Earth Tides, Earthquakes, and Climate Change

Eruptions at geysers and volcanoes are controlled by delicate balances in heat supply and gas and fluid flows within their systems, and by the tortuous pathways that liquid water, steam, and magma take to the surface—balances that can be affected by external forces. Documenting whether geysers and volcanoes respond to tides and earthquakes provides opportunities to quantify their sensitivity to changes in physical stress in the subsurface and to help evaluate whether they are poised to erupt [Seropian et al., 2021].

Past studies have suggested, on the basis of statistical correlations, that small forces exerted by Earth tides can trigger volcanic eruptions. However, statistical tests of tidal influence on volcanic eruptions are limited because of the rarity of eruptions from a single volcano. In contrast, the thousands of geyser eruptions that occur annually form a much broader sample pool on which to base statistical tests. One such evaluation uncovered a lack of correlation between Earth tides and the intervals between geyser eruptions, a finding that suggests that a correlation between Earth tides and volcanic eruptions is also unlikely.

In Yellowstone, some geysers stopped erupting whereas others started erupting, after the magnitude 7.3 Hebgen Lake earthquake in Montana in 1959.Although tides might not affect geyser eruptions, regional and even very distant large earthquakes can. Written accounts document renewed activity of Geysir following large earthquakes in southern Iceland in 1294. In Yellowstone, some geysers stopped erupting whereas others started erupting, after the magnitude 7.3 Hebgen Lake earthquake in Montana in 1959. The magnitude 7.9 Denali earthquake in Alaska in 2002 affected eruptions of some Yellowstone geysers 3,000 kilometers away.

Earthquakes can also promote volcanic unrest and eruptions. Establishing causal relations between earthquakes and eruptions is challenging because few active volcanoes occur in any given area, and changes in the subsurface can take longer to manifest as an eruption. However, geysers erupt more frequently than volcanoes, which again points to the utility of studying geysers as volcanic analogues.

Precipitation trends and climate changes can affect geysers as well. Eruption intervals at Old Faithful Geyser have changed in the past, and it even ceased erupting in the 13th and 14th centuries because of a severe drought. How often geysers erupt may also change in response to seasonal and decadal changes in precipitation, which affect the supply of groundwater that feeds the eruptions.

Volcanoes also display slight seasonal patterns in their eruptions, and they respond to changing climate. As air temperatures warm, for example, glaciers covering volcanoes melt, which in turn reduces pressure on underlying magma. Pressure reduction causes gas bubbles to form, and the buoyant mixture of magma and bubbles is then more primed for eruption.

On longer timescales, rates of volcanism vary over glacial cycles, with more eruptions and larger volumes of magma erupted as glaciers retreat. In line with this observation, we know from dating sinter deposits and from geologic mapping that most geyser fields were inactive during Earth’s last glacial period (which ended between ~20,000 and 12,000 years ago) when they were covered by ice [Hurwitz and Manga, 2017].

Origins and Limits of Life on Earth and Mars A recent geyserite deposit from northern Waiotapu, in New Zealand’s Taupo Volcanic Zone, shows fingerlike formations. Similar formations have been found in silica-rich deposits on Mars. Credit: Kathleen A. Campbell, University of Auckland

Sinter deposits form when hot water erupting from geysers cools and evaporates rapidly at the surface, causing dissolved silica to precipitate as opaline or amorphous (noncrystalline) solids. High-temperature, vent-related sinter that forms in surge and splash zones around or near erupting geysers is termed geyserite. Around geysers and in downslope pools and discharge channels, the complex sedimentary structures preserved in sinter reflect physical, chemical, and biological processes occurring in hot spring subenvironments. For example, sinter textures produced in hot spring fluid outflows record temperature and pH gradients across a given geothermal field, from vents to discharge channels to pools, and from terraces to marsh settings.

Sinter typically entombs both biotic (e.g., microbes, plants, animals) and abiotic (e.g., weathered sinter fragments, volcanic ash, detritus) materials. Geyserite, in particular, serves as an archive of conditions in Earth’s hottest environment on land (up to about 100°C) and of extreme thermophilic (high temperature–adapted) life therein [Campbell et al., 2015].

Research on modern hot springs suggests that extended hydration and dehydration cycles in geyser outflow channels can give rise to prebiotic molecular systems, which hints at a possible role for geysers in the origin of life on Earth.Research on modern hot springs suggests not only that they can host extant life, but also that extended hydration and dehydration cycles in geyser outflow channels can give rise to prebiotic molecular systems that display fundamental properties of biology, such as enclosed, cell-like structures composed of lipids and polymers [Damer and Deamer, 2020]. This observation hints at a possible role for geysers in the origin of life on Earth billions of years ago. Indeed, inferred geyserite deposits associated with rocks containing microbial biosignatures have recently been reported in approximately 3.5-billion-year-old hydrothermal sedimentary deposits in Western Australia [Djokic et al., 2017].

On Mars, silica-rich deposits detected by the Spirit rover amid Columbia Hills in Gusev Crater closely resemble fingerlike sinter textures on Earth. This site was proposed as a landing site for the NASA Mars 2020 mission, which will cache samples for eventual return to Earth. Although the Perseverance rover was instead sent to explore deltaic deposits in Jezero Crater, the digitate silica structures at Columbia Hills remain as biosignature candidates that may one day be collected and brought to Earth for in-depth verification of their origin. Therefore, sinters remain a key target in the search for ancient life on Mars, particularly from the time in its history when volcanoes and liquid water were active at the surface—about the same time that life was taking hold in hot water here on Earth.

In addition to benefiting our understanding of what constitutes life and where it can thrive, advanced biotechnology has also benefited from geyser studies. In 1967, microbiologist Thomas Brock and his student Hudson Freeze isolated the bacterium Thermus aquaticus from the hot waters of Yellowstone’s geyser basins. Later, biochemist Kary Mullis identified an enzyme, named Taq polymerase, in a sample of T. aquaticus that was found to replicate strands of DNA in the high temperatures at which most enzymes do not survive. This discovery formed the basis for developing the revolutionary polymerase chain reaction (PCR) technique in the 1980s (for which Mullis shared the 1993 Nobel Prize in Chemistry). PCR is now the workhorse method used in biology and medical research to make millions of copies of DNA for various applications, such as genetic and forensic testing. Recently, PCR also became widely used for COVID-19 testing.

Exploring for Energy and Mineral Deposits

Sinter deposits can also inform exploration for geothermal energy, helping locate resources, as well as for mineral deposits. Whereas currently active hydrothermal systems provide energy for electricity generation, industry, and agriculture, giant fossil hydrothermal systems host many of the world’s most productive precious metal mining operations [Garden et al., 2020]. Such epithermal ore deposits form in the shallow subsurface beneath geothermal fields as high-temperature fluids—both magmatic and meteoric in origin—gradually deposit valuable metals including gold, silver, copper, and lithium.

Geyserites form at the surface emission points of rising hot fluids tapped from deep reservoirs and can point to completely concealed subsurface ore deposits [Leary et al., 2016], thus informing exploration for mineral resources; they may also contain traces of precious metals themselves.

Geysers in the Solar System

Studies of physical processes in easily observable geysers on Earth can also guide and constrain models proposed to explain eruptions elsewhere in our solar system. The geysers of the icy outer solar system satellites Enceladus (Saturn), Triton (Neptune), and Europa (Jupiter) are similar to Earth’s geysers in that changes of state of materials (e.g., melting and vaporization) drive mixtures of solids and gases to erupt episodically.

NASA’s Cassini spacecraft took this image during its survey of the southern hemisphere geysers on Saturn’s moon Enceladus. The four fractures from which the geysers erupt, referred to as tiger stripes, are approximately 135 kilometers long and cross Enceladus’s south pole. Credit: NASA/JPL/Space Science Institute

At the south pole of the ice-covered ocean world Enceladus, some 100 geysers erupt from four prominent fractures, delivering water from a habitable ocean into space and supplying ice particles to Saturn’s E ring. At Triton, the largest of Neptune’s 13 moons, NASA’s Voyager 2 spacecraft detected surface temperatures of −235°C and geysers that erupt sublimated nitrogen gas. Whether eruptions currently occur on Europa remains debated.

As on Earth, studying physical controls on geyser location, longevity, and eruption intervals on these other worlds can improve our understanding of interactions between their interiors and their surface environments.

Engaging the Public in Research and Conservation Visitors on a boardwalk watch an eruption of Grand Geyser in the Upper Geyser Basin of Yellowstone National Park in June 2012. Credit: Jim Peaco, National Park Service

New sound and visual approaches developed to convey complex patterns in geyser systems may help identify relationships between volcanic signals that might otherwise be overlooked.Tourists and amateur enthusiasts are captivated by the views and sounds of geyser eruptions. These spectacular events also provide public showcases for curiosity-driven scientific research. For example, new sound and visual approaches developed to convey complex patterns in geyser systems could provide valuable educational tools and may also help identify relationships between volcanic signals—such as surface deformation and seismicity indicating preeruptive activity—that might otherwise be overlooked.

Characterizing the sources of thermal water feeding geyser eruptions and mapping the subsurface hydraulic connections between geyser fields and adjacent areas are needed to protect and preserve these natural wonders from human impacts. Geothermal energy production and hydroelectric dam siting have drowned or driven more than 100 geysers to extinction in New Zealand and in Iceland, for example, and geyser eruptions completely ceased in Steamboat Springs and Beowawe in Nevada owing to exploitation of geothermal resources. In contrast, some dormant geysers in Rotorua, New Zealand, resumed erupting a few decades after geothermal extraction boreholes were shut down.

Geysers are curious and awe-inspiring natural phenomena, and they provide windows into a broad range of science questions. They deserve both our wonder and our protection.

Acknowledgments

We thank the communities and agencies that enabled research on land they own or manage (Amayras Communities of Caspana and Toconce in El Tatio, Chile; Environment Agency of Iceland for research near Strokkur; the Department of Conservation, Wai-O-Tapu Thermal Wonderland, the Ngati Tahu–Ngati Whaoa Runanga Trust, and Orakei Korako Geothermal Park and Cave in New Zealand; and the National Park Service in the United States for research in Yellowstone). We thank Wendy Stovall, Lauren Harrison, and Mara Reed for constructive reviews. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government.

Many activities required to power and sustain human society have the potential to create earthquakes. This is known as ‘induced seismicity’. Historically, the first observations of induced seismicity were connected to mass displacement, such as during gold mining in South Africa as early as 1894, and coal mining.

Many activities required to power and sustain human society have the potential to create earthquakes.Another cause is reservoir impoundment for water supply and power generation, such as the Lake Meade, Hoover Dam M 5 event in 1939 (Foulger et al. 2018). The largest detected induced event to date was the M 6.3 Koyna earthquake in 1967 (Gupta et al. 2015). This is set to continue with more than 3,500 dams presently being built or planned (Zarfl et al., 2019).

Meanwhile, components of renewable energy technologies such as wind turbines, solar cells, and batteries, require a variety of minerals and metals; thus, new mines will be developed in the forthcoming decades to extract these needed resources (Mining Equipment Market Share & Growth Report, 2020-2027).

Induced seismicity can also be caused by underground industrial activities such as geothermal energy, geological sequestration of CO2 (In Salah Project, microseismicity), exploitation of unconventional hydrocarbon reservoirs (Blackpool, M 2.3), and storage of gas in geologic formations (CASTOR UGS project offshore Spain, M 4) to cover seasonally-varying energy demand. These operations require more invasive techniques for fluid injection and production, and increase the risk of seismic activity, sometimes at close proximity to urban centers (e.g. Suckale, 2010; Ellsworth, 2013). Consequently, certain regions such as Oklahoma and Alberta have been experiencing a long-term increase in induced earthquake rates well beyond historic levels with some events causing local damage and destruction (Ellsworth, 2013).

Evolution of the number of earthquakes of a magnitude greater than 3 between 1975 and 2020 in mid-continental USA. The data comes from the ANSS catalogue of USGS (2017). The statistics show the dramatic increase of the number of earthquakes attributed to the injection of significant amounts of wastewater into the Arbuckle formation in Oklahoma, USA. This figure is an update of versions by Rubinstein and Mahani (2015) and Ellsworth (2013).

Research is urgently needed to assess whether human-induced seismic hazards can be controlled, and whether an improved understanding of the underlying physical processes may help mitigation efforts.Project developers and regulators thus face increasing public awareness and concern about the damaging potential of induced seismicity. Owing to public opinion pressure, human-induced earthquakes have often forced rapid termination of subsurface activities (for example, coal mining in the German Ruhr Area, the Basel geothermal project in Switzerland, and the CASTOR Underground Gas Storage in Spain). Research is therefore urgently needed to assess whether human-induced seismic hazards can be controlled, and whether an improved understanding of the underlying physical processes may help mitigation efforts.

One of the key outstanding questions is whether it is possible to control or reduce induced seismicity rates and maximum magnitudes in order to mitigate the resulting risk to society and critical infrastructures (e.g. McGarr 2014; Galis et al., 2017; McGarr and Barbour, 2018; Kwiatek et al., 2019; Shapiro et al., 2013; Shapiro et al., 2011; van der Elst et al., 2016). There is a clear need for improved seismic hazard assessment and operational forecasts of induced seismicity for different types of subsurface operations and tectonic settings.

General mechanisms controlling the occurrence of induced seismicity include elastic loading and unloading and modification of pore fluid pressure and stress conditions due to fluid injection and production in reservoirs and surrounding rocks (Segall, 1992). Although pore pressure increase and effective stress reduction have traditionally been thought to produce most induced events, recent observations suggest a more complex suite of mechanisms. Sudden rate changes and long-range effects highlight the importance of the interplay between fluid pressure  and solid stress (e.g. Rudnicki, 1986; Segall and Fitzgerald, 1998; Altmann et al., 2014; Goebel et al., 2017). Shallow faults may promote aseismic deformation which can trigger seismic events at larger distances (Cornett et al., 1997; Bourouis et al., 2007; Guglielmi et al., 2015). Fluid flow can trigger earthquakes and potentially lead to cascading failure of fault systems  leading to a series of seismic events (Llenos and Michael, 2013; Sumy et al., 2014).

A new cross-journal special collection in JGR: Solid Earth and Earth and Space Science, entitled Understanding and anticipating induced seismicity: from mechanics to seismology solicits papers that contribute to the understanding of induced seismicity at different spatial and temporal scales.

A new cross-journal special collection solicits papers that contribute to the understanding of induced seismicity at different spatial and temporal scales.Induced seismicity research involves many different disciplines from geomechanics and engineering to seismology and geodesy, requiring a broad suite of analytical, numerical, and statistical analysis tools to improve theoretical understanding and disaster mitigation. The special collection encourages contributions on current scientific challenges in an effort to advance physical process understanding at different scales from laboratory to mesoscale injection tests and reservoir to regional-scale models and observations.

—Birgit Müller (Birgit.mueller@kit.edu, 0000-0002-5668-1437), Karlsruhe Institute of Technology, Germany; Mai-Linh Doan, ( 0000-0002-6437-9756), Université Grenoble-Alpes, France; Thomas Goebel ( 0000-0003-1552-0861) The University of Memphis, USA; Yajing Liu ( 0000-0002-5323-8077), McGill University, Canada; Patricia Martínez-Garzón ( 0000-0003-4649-0386), GFZ German Research Centre for Geosciences, Germany; Tom Mitchell ( 0000-0003-0809-1528), University College London, UK; and Ilia Zaliapin ( 0000-0001-6257-0517), University of Nevada, USA