VOL. 102 | NO. 1 Creating Sustainable Cities JANUARY 2021 A Little-Known Mass Extinction

Finding Data Points in Newspapers

Tracking Magnetic Fields Want to understand a planet? Take out your compass.

FROM THE EDITOR

Editor in Chief Heather Goss, AGU, Washington, D.C., USA; [email protected] AGU Staff Vice President, Communications, Amy Storey The Wobbly Anomaly and Other Marketing,and Media Relations Magnetic Weirdness Editorial Manager, News and Features Editor Caryl-Sue Micalizio Science Editor Timothy Oleson always find it fascinating that something happening in News and Features Writer Kimberly M. S. Cartier News and Features Writer Jenessa Duncombe such a remote, faraway place—Earth’s core—can have “I a profound impact on our lives way out on the surface,” Production & Design said Julie Bowles as she helped us develop this issue. Bowles Manager, Production and Operations Faith A. Ishii is an associate professor at the University of Wisconsin-­ ​ Production and Analytics Specialist Anaise Aristide Assistant Director, Design & Branding Beth Bagley Milwaukee­ and Eos’s science adviser for AGU’s Geomagnetism, Senior Graphic Designer Valerie Friedman Paleomagnetism, and Electromagnetism section. Senior Graphic Designer J. Henry Pereira We dug into that impact Earth’s magnetic field has on all of Graphic Design Intern Abby Margosian us for our January issue of Eos. A big reason we thought the Marketing topic was worth an entire issue is, as Bowles said, “there is a Communications Specialist Maria Muekalia lot of interesting crossover between the magnetism commu- Assistant Director, Marketing & Advertising Liz Zipse nity and many other Earth science communities.” Indeed, this Advertising topic was originally suggested by Carol Stein, at the Depart- Display Advertising Steve West ment of Earth and Environmental Sciences at the University of Illinois at Chicago, Eos’s sci- [email protected] Recruitment Advertising [email protected] ence adviser for AGU’s Tectonophysics section, who noted the importance of understanding magnetism for so many scientists throughout AGU’s sections. Science Advisers You can flip through these pages to see that convergence. Manasvi Lingam starts us off on Geomagnetism, Paleomagnetism, Julie Bowles page 24 with an appropriately poetic introduction for a discussion about a force we cannot see and Electromagnetism generated by a core we cannot reach and how that has created unique conditions for the only Space Physics and Aeronomy Christina M. S. Cohen Cryosphere Ellyn Enderlin place in the universe where we know life exists. “Resolving the riddle” of these relationships, Study of the Earth’s Deep Interior Edward J. Garnero writes Lingam, requires knowledge from geology, astronomy, plasma physics, microbiology, Geodesy Brian C. Gunter evolutionary biology, and myriad other disciplines. History of Geophysics Kristine C. Harper The ideas raised here lead us into another fascinating discussion about “how pervasive mag- Planetary Sciences Sarah M. Hörst Natural Hazards Michelle Hummel matism is throughout the solar system,” said Stein. So on page 36, we offer you “A Field Guide Volcanology, Geochemistry, and Petrology Emily R. Johnson to the Magnetic Solar System.” This tourist excursion leads you from Mercury out to the ice Societal Impacts and Policy Sciences Christine Kirchhoff giants and explains what your magnetic compass will show you at each destination and what Seismology Keith D. Koper Tectonophysics Jian Lin that means about the planet beneath your feet. We hope you enjoy this interplanetary adven- Near-Surface Geophysics Juan Lorenzo ture. Earth and Space Science Informatics Kirk Martinez Finally, we couldn’t cover studies of the magnetic field without recognizing how truly strange Paleoceanography and Paleoclimatology Figen Mekik Mineral and Rock Physics Sébastien Merkel it is. In “The ­Herky-​­Jerky Weirdness of Earth’s Magnetic Field” (p. 30), we take a look at the Ocean Sciences Jerry L. Miller big dent known as the South Atlantic Anomaly, the origin of ­so-called​­ geomagnetic jerks, and Global Environmental Change Hansi Singh other oddities, “some of which have important societal implications,” according to Bowles. Education Eric M. Riggs Hydrology Kerstin Stahl Unlike our pal Dr. Conrad Zimsky—did you really think I’d get all the way through this with- Tectonophysics Carol A. Stein out a reference to The Core?—we know our understanding of geomagnetism is a lot better than Atmospheric Sciences Mika Tosca “a best guess.” We eagerly look forward to seeing more in this rapidly advancing science and Nonlinear Geophysics Adrian Tuck Biogeosciences Merritt Turetsky covering it here in the pages of Eos. Hydrology Adam S. Ward Diversity and Inclusion Lisa D. White Earth and Planetary Surface Processes Andrew C. Wilcox Atmospheric and Space Electricity Yoav Yair GeoHealth Ben Zaitchik

©2021. AGU. All Rights Reserved. Material in this issue may be photocopied by individual scientists for research or classroom use. Permission is also granted to use short quotes, figures, and tables for publication in scientific books and Heather Goss, Editor in Chief journals. For permission for any other uses, contact the AGU Publications Office. Eos (ISSN 0096-3941) is published monthly by AGU, 2000 Florida Ave., NW, Washington, DC 20009, USA. Periodical Class postage paid at Washington, D.C., and at additional mailing offices. POSTMASTER: Send address changes to Member Service Center, 2000 Florida Ave., NW, Washington, DC 20009, USA Member Service Center: 8:00 a.m.–6:00 p.m. Eastern time; Tel: +1-202-462-6900; Fax: +1-202-328-0566; Tel. orders in U.S.: 1-800-966-2481; [email protected]. Submit your article proposal or suggest a news story to Eos at bit.ly/Eos-proposal. Views expressed in this publication do not necessarily reflect official positions of AGU unless expressly stated. Randy Fiser, Executive Director/CEO

SCIENCE NEWS BY AGU // Eos.org 1 CONTENT

18 30

24 36

Features

18 Converging on Solutions 30 The Herky-Jerky Weirdness to Plan Sustainable Cities of Earth’s Magnetic Field By Donald J. Wuebbles et al. By Jenessa Duncombe

Closing the gap between urban challenges and Our planetary armor drifts, shivers, and morphs into appropriate solutions. its next configuration.

24 Habitability and the 36 A Field Guide to the Magnetic Evolution of Life Under Solar System Our Magnetic Shield By Bas den Hond By Manasvi Lingam Grab a bag, your interplanetary passport, and most important, your compass. Connecting the dots between Earth’s inner core and the organisms thriving on the surface.

Cover: NASA

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9 15

12 43

Columns

From the Editor Research Spotlight 1 The Wobbly Anomaly and Other Magnetic Weirdness 42 A Juno Era Model of the Jovian Magnetosphere 43 How Long Does Iron Linger in the Ocean’s Upper Layers? | News Capturing Heat-Driven Atmospheric Tides on Mars 5 Newspaper Archives Uncover Flood Risk 6 Powerful Glacial Floods Heave Himalayan Boulders Editors’ Highlights 8 What Controls Giant Subduction Earthquakes? 44 Ensemble Modeling of Coronal Mass Ejection Arrival 9 A Little-Known Mass Extinction and the “Dawn at 1 Astronomical Unit | More Clustered Clouds Amplify of the Modern World” Tropical Rainfall Extremes 11 How Infrastructure Standards Miss the Mark on Snowmelt Positions Available 12 Bat Guano Traces Changes in Agriculture and Hurricane 45 Current job openings in the Earth and space sciences Activity 13 Wildfires Threaten West Coast’s Seismic Network Postcards from the Field Opinion 49 A field trip to Pike’s Peak 15 #GeoGRExit: Why Geosciences Programs Are Dropping the GRE

AmericanGeophysicalUnion @AGU_Eos company/american-geophysical-union AGUvideos americangeophysicalunion americangeophysicalunion

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NEWS

Newspaper Archives Uncover Flood Risk

hen figuring out flood risk, it’s “When it comes to flood risk, what we important to collect data on past know is our probabilities calculations extrap- W flooding events. In some areas, olated over a map—that doesn’t mean that detailed records of rainfall and stream gauges they reflect the real situation,” said Åse are available. But in regions that are dry or Johannessen, a water governance researcher sparsely monitored, this critical information at Lund University in Sweden who was not is missing. involved in the study. Enter a different kind of record: newspa- Johannessen said that newspaper stories pers. Areas that have experienced flooding record real, not modeled, events, so they can likely had an accompanying local news story be a good validation tool for risk mapping. documenting the event, including what par- “Not only that, it’s also information about the ticular areas were flooded and the extent of actual damage and in all kinds of detail,” she damage. The United Arab Emirates, including Dubai, above, is said. Researchers have now used these newspa- prone to flash floods. Local newspapers are excel- per records to act as a validation for flood risk lent proxies for flood risk maps, new research Future Flood Prediction maps. When they compared their flood maps shows. Credit: iStock.com/Viktoriya Fivko Yagoub called newspapers a “forgotten trea- to almost 20 years of newspaper articles, they sure” in defining areas of flood risk. “I came found a high correlation between reported to know that newspaper archives contain a floods and predicted ­high-risk​­ areas. wealth of information, and many research The scientists noted that their methods mostly in mountainous terrain. The remaining questions could be formulated based on this could be used by other researchers working in 15% of land was urban areas and coastal plains, information,” he said, adding that it would be areas with spotty flood data. Their work may considered high to very high flood risk zones. even better if newspapers included accurate also be useful to policymakers and disaster Yagoub explained that his team wanted to geographic coordinates of flooding events. managers to better prepare for future flooding. make sure these high-­ ​­risk areas had flooded Johannessen also thinks newspapers pro- in the past. To check their model, the research- vide a wealth of information, including how Use What You Have ers turned to newspapers. people behave in a flood. “For example, if you In the arid United Arab Emirates (UAE), The researchers used five local papers (both have a flood in a poor community, many peo- flooding might not spring to mind as a regu- ­Arabic- and ­English-language​­ publications) to ple actually stay put because they want to save lar event. But flash floods do occur in the UAE find records of historical flood events. “Read- their assets.” Knowing community behaviors and are made worse by the proximity of cities ing many newspaper reports and scanning can help emergency managers better prepare to mountain foothills and the extent of urban them for flood impact is a challenge,” said for extreme events. impermeable surfaces, such as pavement. Yagoub. “To automate this process, a Java pro- She noted that newspapers also highlight Using geographic information systems gram was developed to read the document file the vulnerabilities in a system: transport dis- (GIS), scientists can map out areas that may and extract important flood damage informa- ruption, accidents, and weaknesses of infra- be prone to flooding using familiar criteria tion using ­text-​­processing functions.” structure. “[Those vulnerabilities are] not like slope, geology, rainfall, geomorphology, captured by a flood risk map.” and land use. But these maps parse out only “People talk about a cocktail of risks—that the potential risk. A historical measurement you don’t really know which risks influence of floods—including locations, magnitudes, They compared their flood each other and have a cumulative cocktail of and frequencies—is an effective field check effects,” Johannessen explained, adding that of predictions. maps to almost 20 years of newspapers can help fill in the details of what “The proverb says, ‘Necessity is the mother newspaper articles. happened during historical floods. of invention,’” said Mohamed Yagoub, pro- The goal of the study was “prevention, pre- fessor of remote sensing and GIS at UAE Uni- vention, prevention,” said Yagoub. “This type versity and lead author of the study, which of ­flood-​­prone area map in digital form may appeared in Natural Hazards (bit​.ly/­GIS​ be used as a database that could be shared -modeling).­ “Researchers are sometimes Using such a text-­ ​­mining program, the among various government and nongovern- faced with nonavailability and non­ team searched for words such as Fujairah, ment agencies concerned about floods.” accessibility of data. Therefore, they have to flood, evacuate, and water. From there, they “If planners can really understand the go around and use proxy means.” gathered information on individual flooding dynamics of a city and how to plan and where events, including the general location, date, to put measures in a much more specific way, Mining the Archives and what sort of damages occurred. I think [this type of work] can be a big contri- Using GIS, Yagoub and his team generated a The team overlaid the historical events bution,” said Johannessen. traditional flood risk map for the area sur- documented in newspaper articles on the rounding Fujairah, capital of the Fujairah map of potential flood zones to compare. emirate in the UAE. About 85% of the land area They found that 84% of the reported floods By Sarah Derouin (@Sarah_Derouin), Science was in medium and low flood risk zones, were in high to very high flood risk zones. Writer

SCIENCE NEWS BY AGU // Eos.org 5 NEWS

Powerful Glacial Floods Heave Himalayan Boulders

heaved by earthquakes. Repeated temblors over time—a region’s earthquakes tend to strike every few hundred or thousand years— would have yielded a larger spread in ages rather than a single cluster, the researchers concluded.

Lots of Water Huber and his team next used three different metrics to estimate the water flow velocities necessary to have moved the boulders. They found velocities in the range of roughly ­4-17 meters per second, which, when translated into peak discharge values for either the Tri- shuli or Sunkoshi river channel, yielded val- ues ranging from about 1,300 to 300,000 cubic meters per second. (For comparison, the Mis- sissippi River discharges roughly 16,000 cubic meters of water per second into the Gulf of Mexico.) That’s higher than the levels associated with even monsoonal flooding, the research- Enormous boulders in Himalayan riverbeds, like this one in the Sunkoshi River channel, were likely transported ers calculated. “Our discharges are consi­ by glacial lake outburst floods. Credit: Maarten Lupker derably bigger than most monsoonal dis- charges,” said Huber. “You need lots of water.” A plausible culprit, Huber and his col- normous boulders—10 meters or more roundings. That’s a telltale sign that they’ve leagues suggested, is a glacial lake outburst in diameter—litter many river channels been transported at some point in the past, flood. These events, which occur worldwide, Ein the Himalayas. Scientists have now the researchers concluded. But the Trishuli involve the sudden drainage of a ­glacier-​­fed age dated several of these behemoths and and Sunkoshi river channels, where the sci- lake. (Many such lakes are bounded by fragile estimated the flow velocities necessary to entists did their fieldwork, are at too low an glacial moraine, which is apt to give way.) have heaved them. elevation to have been glaciated in the past, Glacial lake outburst floods have frequently The boulders were likely set in motion meaning that the rocks couldn’t have hitched struck in the Himalayas; one roared down the thousands of years ago by the powerful forces a ride with a glacier. Sunkoshi River valley in 2016. of glacial lake outburst floods, the researchers An uptick in glacial lake outburst flood suggested. These findings shed light on how Measuring “Sunburn” activity roughly 5,000 years ago makes sense, infrequent events can shape landscapes. Huber and his collaborators focused on Huber and his team proposed. Climate prox- 16 boulders ranging in diameter from about ies such as ice and sediment cores record A Rocky Mystery 5 to 30 meters. They clambered to the top of ­drier-​­than-​­normal conditions around that In 2016, Marius Huber, a geoscientist at the each rock to collect samples for cosmic ray time, and glaciers tend to shrink when there’s University of Lorraine in Nancy, France, and exposure dating to estimate how long ago the less precipitation, said Huber. Because reced- his colleagues traveled to Nepal to solve a rocks had settled into their current positions. ing glaciers form moraines, setting up the rocky mystery: the origin of the ­house-​­sized The technique hinges on measuring minute conditions for glacial lake outburst floods, boulders often found in or near Himalayan changes in rock chemistry, which arise when this time period was essentially primed for river channels. “No one really knows where energetic protons—emitted by distant super- heaving around big boulders, the researchers they’re coming from,” said Huber. nova explosions—slam into the boulders over concluded. These results were published in Boulders of that size can have a significant time. “Cosmogenic radiation alters the sur- Earth Surface Dynamics (bit​.ly/­boulder​ impact on the local hydrology, said Mike face of the rock over time,” said Huber. “It’s -­emplacement). Turzewski, a geomorphologist at Pacific like a sunburn.” It’s worth returning to the Himalayas to Lutheran University in Tacoma, Wash., not The researchers found that the boulders’ measure more boulders in the future, said involved in the research. “They can com- ages ranged from fewer than 500 years to up Huber. “We’ll get a better picture of what’s pletely change the direction of the channel.” to about 13,000 years. However, more than going on.” The boulders stick out like sore thumbs not half of the rocks had ages that clustered only because of their sizes but also because of around 5,000 years. That pattern was strik- their compositions—their lithologies tend to ing, said Huber, and informative. It meant By Katherine Kornei (@KatherineKornei),

differ from those of their immediate sur- that the boulders probably weren’t being Science­ Writer Right: XXXX Top XXXXXX; This Page: Opposite Page:

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What Controls Giant Subduction Earthquakes?

and the rate of subduction. Specifically, a young oceanic plate with a rapid rate of sub- duction was expected to produce the biggest earthquakes. But conditions at the Sumatran and Japanese subduction zones didn’t fit into this classical view. “That idea, which was wonderful in its simplicity, didn’t work,” said Sobolev. “So the question is, What are the controlling fac- tors?” In their paper, published in Geochemistry, Geophysics, Geosystems, Muldashev and Sobolev used a 2D cross-­ ​­scale numerical model they developed when Muldashev was a graduate student at Potsdam (bit​.ly/­earthquake​ -­magnitude). It simulates subduction pro- cesses on timescales of millions of years but can also zoom in to timescales as small as 40 seconds to capture the activity of earth- quakes. They varied multiple factors, includ- ing subduction rates, the geometry of the sub- duction zone, and the amount of friction between the plates, to see which factors led to earthquakes with the greatest magnitude. The magnitude 9.1 Tohoku earthquake that devastated parts of Japan in 2011 came as a surprise because it The modeling pointed to the angle of sub- occurred in a region that wasn’t thought to be able to produce giant earthquakes. Credit: William Saito/Flickr, duction of the oceanic plate as the most CC ­BY-​­NC-​­ND 2.0 (bit​.ly/­ccbyncnd2-­0) important factor—the flatter the dipping angle of the slab, the larger the possible mag- nitude of the earthquake. This is because with a shallow angle, the slab will have a longer iant earthquakes—those greater than zone, leading to giant subduction earth- surface within the temperature range capable magnitude 8.5—are rare. That’s good quakes. of generating earthquakes, creating a wider Gnews for people living on the coast- seismogenic zone. A low level of friction in lines along subduction zones where giant Earthquake Surprises the subduction zone is also important for cre- earthquakes occur but bad news for geophys- Two of the largest earthquakes (and subse- ating giant earthquakes, so a less rough ocean icists who want to understand where and quent tsunamis) ever observed occurred in bottom or thick sediments that can smooth why they strike. Now a new study that models the past 2 decades: the 2004 Sumatra earth- over a rough subducted seafloor were also seismic activity in subduction zones has pin- quake and the 2011 Tohoku earthquake. Both critical. These characteristics allowed the pointed the factors responsible for Earth’s had an estimated magnitude of 9.1, which rupture to travel deeper, which also increased largest earthquakes. surprised scientists. “No one expected such the rupture’s width. “We have just a few hundred of these very large earthquakes at those places,” said Although the results contradict the clas- big events over the whole history,” said Sobo­lev. sical view of giant earthquakes from the Andreas Schäfer, a disaster researcher at Influential research dating back to 1980 1980s, they confirm findings from recent Karlsruhe Institute of Technology who was proposed that earthquake magnitude numerical modeling efforts and statistical not involved in the new study. “Empirically depended on the age of the subducting plate analyses and point to the overall size of the speaking, that’s not a lot of data.” rupture zone as the key to producing giant To sidestep this data problem, Iskander earthquakes. Muldashev, a geophysical modeler at Bremen One limitation of the study is that because University, and Stephan Sobolev, a geo­ “We have just a few of the complexity of the models and the con- dynamic modeler at GFZ Helmholtz Centre straints of available computing power, the Potsdam, developed numerical models that hundred of these very big model is 2D, although the researchers simulate seismic cycles for subduction zones. [earthquakes] over the extrapolated the results into 3D. “These The models showed that a shallow angle of 3D models, in my view, are still stretched subduction for the sinking oceanic plate and whole history…. Empirically 2D models that don’t really capture the 3D a thick layer of sediments in the trench where speaking, that’s not a lot complexity of real subduction zones,” said it meets the continental plate were the most Wouter Schellart, a geodynamicist at Vrije important factors in creating a large rupture of data.” Universiteit Amsterdam. To take the next

8 Eos // JANUARY 2021 NEWS

A Little-­ Known​­ Mass Extinction ​ and the “Dawn of the Modern World”

assive volcanic eruptions followed by climate change, widespread Mextinction, and, eventually, the emergence of new life forms: It sounds like the story of one of Earth’s five great mass extinctions. Now researchers say the same description applies to a lesser known—but highly conse- This map displays subduction zones predicted to quential—event referred to as the Carnian generate earthquakes with maximum magnitudes of Pluvial Episode (CPE), 233 million years ago. 8.­8–​­9.2 (orange) and more than 9.2 (red). Circles Unlike some of the more dramatic mass show the locations of previous earthquakes with extinctions, the signature of the CPE is diffi- magnitudes greater than 8.5 in subduction zones. cult to trace. But working across disciplines The earliest crocodilian reptiles, like Hespero- Red circles indicate compressive upper plate strain and continents, a team of scientists has been suchus, arose during the Carnian. Credit: (UPS), and green circles indicate neutral UPS. Dot- able to piece together a broad overview, iStock.com/Aunt_Spray ted circles indicate preinstrumental events. Credit: showing that it was a period of rapid biologi- Muldashev and Sobolev, 2020, https://­doi​.org/­ cal turnover on a global scale. 10.1029/­2020GC009145, CC BY 4.0 (bit​.ly/­ccby4​-­0) The accumulated evidence, including results of a new fossil analysis, shows that Intense rains, global the CPE was a major extinction event. More warming, and probably than that, however, the evidence indicates step, Schellart thinks researchers should that it was a period of new beginnings. Most widespread ocean anoxia extend the models into three dimensions, notably,­ the CPE marks the start of the dino- taking into account variables that might saurs’ ascendance to ubiquity and ecological and acidification resulted affect the estimated magnitudes, such as the dominance. in the extinction of one curvature of the subduction zone or irregu- Ecologically, the researchers said, the Car- larities in the plate boundaries. nian extinction marks the “dawn of the mod- third of all marine species ern world.” The new study was published in during the Carnian. What’s the Worst That Could Happen? Science Advances (bit​.ly/­carnian​-­extinction). Muldashev and Sobolev applied their findings to estimate potential ­worst-​­case earthquake Extinction and Recovery scenarios for subduction zones worldwide and The CPE is named for the stage of the Late Tri- developed maps highlighting areas where assic in which it occurred—the Carnian—and It was an ill-­ timed​­ disaster for a planet still giant earthquakes could occur. The areas align for its signature feature: rain. A lot of rain, in only very slowly recovering from the biggest well with the locations of giant earthquakes four main pulses lasting over a million years, mass extinction of them all, at the end of the from the 20th and 21st centuries and with fell across much of the supercontinent of Permian period just 20 million years earlier. similar maps based on statistical analyses of Pangaea. “The ­end-​­Permian extinction wiped out 95% earthquake observations. The agreement The rains were accompanied by global of all marine species, and the Triassic was a suggests that the community may be getting warming and probably widespread ocean time of recovery,” Benton noted. “It now a better handle on what controls the sizes of anoxia and acidification, the researchers said. seems the CPE was a key punctuation [in that giant earthquakes and where they might All told, their analysis shows that these fac- process].” strike. “From a scientific perspective, it is tors resulted in the extinction of one third of “A key feature of the CPE is that extinction good to know that we are making progress,” all marine species. Ecosystems on land also was very rapidly followed by a big radiation,” said Schäfer. underwent massive transformations during said lead author Jacopo Dal Corso, a geology Muldashev cautions, however, that we still and after the CPE, including the loss of dom- professor at the China University of Geosci- don’t know enough to predict with any pre- inant plant and herbivore species. ences in Wuhan. “A number of groups that cision where future giant earthquakes will Study coauthor Mike Benton, a professor of have a central role in today’s ecosystems occur. “So far, with the tools and knowledge vertebrate paleontology at the University of appeared or diversified for the first time in and the records that we have, we cannot make Bristol in the United Kingdom, said one of the the Carnian.” good predictions,” he said, “but this is one team’s goals was to determine the ranking of Benton noted that this period saw “the rise step forward.” the Carnian event among other mass extinc- of modern reefs and plankton in the oceans tions. “It appears not as substantial as the and the rise of modern tetrapod groups, ‘big five,’ but not far off, and with proper including frogs, lizards, turtles, crocodilians, By Patricia Waldron (@PatriciaWaldron), analysis in the future it might turn out to be dinosaurs, and mammals...along with some Science­ Writer of similar magnitude,” he said. important plant groups such as conifers, and

SCIENCE NEWS BY AGU // Eos.org 9 NEWS

underestimate because much of the volcanic rock has since been subducted. Researchers think that this release was the trigger for the climatic and biological changes of the CPE. The new study is the first comprehensive review of the timing and global impact of the Wrangellia eruptions and their probable link to the climate episode and mass extinction. The work draws on studies from geological, paleontological, and climatological literature conducted in Europe, China, and South Amer- ica. To this the researchers added a new anal- ysis of two large fossil databases representing thousands of collections to demonstrate the magnitude of extinction and origination associated with the CPE. “In our review we were able, through a long work of synthesis and revision of available information, to show with a high resolution The Carnian Pluvial Episode was sandwiched between two of the largest mass extinctions, the end Permian and the synchroneity between biological and the end Triassic. Credit: D. Bonadonna/MUSE, Trento environmental changes we observe in the rocks of 233 million years ago,” Dal Corso said. The scientists said that much work remains to more precisely uncover the scope of the some new groups of insects.” All of this inno- The Wrangellia Eruptions Carnian extinction, its link to the Wrangellia vation, he said, forms much of the basis of Other mass extinctions are known to have eruptions, and possibly other volcanic events. modern ecosystems. “Even the dinosaurs, as been caused by climate change initiated by They hope the new review will help bring the birds, are part of our modern fauna.” volcanism, and researchers say the same is CPE to the attention of a broader research Gerta Keller, a geology professor at Prince­ probably true for the Carnian. During this community. ton University who was not part of the study, time a series of enormous eruptions occurred “Until now,” Dal Corso said, “the Carnian said the work sheds new light on “one of the in Wrangellia, then an equatorial island Pluvial Episode has been the research topic of least known and underrated mass extinction region off the coast of Pangaea. The Wrangel- a very small community of scientists. I think events. I congratulate the authors for placing lia basaltic accretions now form a substantial that many people were unaware of it or of its the Carnian extinction on the map with the part of western Canada. importance.” other five big mass extinctions, among which Researchers estimate that Wrangellia vol- it may eventually take its place after further canism produced more than a million cubic investigations.” kilometers of basalts—but that may be an By Scott Norris (@norris_sd), Science Writer

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10 Eos // JANUARY 2021 NEWS

How Infrastructure Standards Miss the Mark on Snowmelt

Flight Center, and complete picture than NOAA’s standard Jennifer Jacobs, a design values. civil engineering To do this, they used data from a University professor at the of Arizona SWE and snowmelt product and University of New the national Snow Data Assimilation System, Hampshire, cre­ or SNODAS, data set of SWE and snowmelt ated a map that across the continental United States. Com- accounts for snow- bining statistical and mathematical methods, melt across the Cho and Jacobs used those numbers to map con­tinental Unit- annual maximum SWE and weekly snowmelt ed States (bit​.ly/­ levels. snowmelt-​ ­map). It They saw that regions with high SWE and shows that by not large snowmelt events were closely linked. The including snow- mountainous regions in the western United melt levels, NOAA States boasted the highest extreme SWE and Atlas 14 might be snowmelt values. When they compared their providing civil en‑­​ map of weekly snowmelt plus precipitation Snowmelt was one of the factors that figured into the spillway failure at California’s gineers in some levels to NOAA’s precipitation atlas, they saw Oroville Dam, above, in 2017. Credit: California Department of Water Resources regions with an that in 23% of 44 states for which NOAA had inaccurate idea of the necessary data, the combined snowmelt flood risks. and precipitation levels were higher than “You look at NOAA’s precipitation values. alifornia’s Oroville Dam holds back a some of the more extreme melt events, This difference means that in those areas, reservoir that provides water for and almost all of them have occurred in the mostly in western, north central, and north- C23 million people. In February 2017, last 10 years or so, which is a warning that eastern regions, civil engineers are designing rainstorms doused the area and filled the res- as things get warmer, particularly in the win- infrastructure on the basis of precipitation ervoir beyond its normal capacity. Excess ter, you have the potential for added hazard values that might be too low. “Finding that a water was released through the main spill- from snow melting fast,” said Henn. “That flood can be larger than what the NOAA map way, but the structure failed, and 188,000 wasn’t a hazard that used to exist when a lot shows you means that you might have people living downstream evacuated to avoid of our older infrastructure was designed.” underdesigned your infrastructure,” said potential floods. NOAA Atlas 14 works well for most parts of Leung. Several factors contributed to the spillway the country where snowmelt isn’t a big con- Cho hopes that their findings can enhance failure, and one of them was snow. Warm cern, but for regions with heavy snowpack— current guidelines, but for the moment, the temperatures and rain melted much of the like the mountainous western United States, research has limited applications and doesn’t unusually deep snowpack in the Sierra the north central United States, and the consider the changing climate. “The risk of Nevada mountains that winter, which ran off Northeast—NOAA’s values are incomplete. extreme precipitation and snowmelt events into the reservoir below. “That kind of information is useful, but not is increasing as things get warmer,” said “You wouldn’t have had such a severe inci- completely accurate,” said Lai-­ ​­yung Ruby Henn. Although the current study is a good dent if there wasn’t so much water coming Leung, a Battelle fellow at Pacific Northwest starting point, “if we’re designing based on into the lake that they had to let out really, National Laboratory. “Flooding is not just data that might be 30 years old, it might really fast,” said Brian Henn, a machine about precipitation.” It’s also about snow- already be out of date.” learning scientist focusing on global climate melt. Cho is working on that problem and cur- models at the investment and philanthropic “In places where you have snowpack in the rently trying to determine how climate company Vulcan Inc. wintertime that is particularly problematic,” change will influence their values. “Based on In parts of the United States, snowmelt said Leung. this climate issue, the standard values should presents a flood hazard. Although snow usu- be updated regularly in the future to provide ally melts gradually as winter gives way to Mapping Snowmelt the most robust guidance for engineering or spring, if it melts rapidly because of warm Knowing the hazards posed by snowmelt-­ ​ water resource management,” he said. spells or ­rain-​­on-​­snow events, the runoff ­driven floods, Cho and Jacobs analyzed snow “It’s important for us to recognize that into rivers can lead to severe floods. In recent water equivalent (SWE, a measure of the past information is not necessarily the only years, ­snowmelt-​­driven floods have become amount of water contained in snowpack) and information that you should use for designing a more urgent concern. But NOAA Atlas 14, a snowmelt data across the continental United your infrastructure,” said Leung, “because dataset relied on by civil engineers to design States. They combined SWE and snowmelt things are changing.” flood-resilient infrastructure, only accounts values with precipitation data to create for liquid precipitation, not snowmelt. design values, values used when planning To address this, Eunsang Cho, a post­ infrastructure that needs to withstand By Jackie Rocheleau (@JackieRocheleau), doctoral researcher at NASA’s Goddard Space extreme events, that could offer a more Science­ Writer

SCIENCE NEWS BY AGU // Eos.org 11 NEWS

Bat Guano Traces Changes in Agriculture ​ and Hurricane Activity

thick in some places—have remained largely unmolested by humans. The excrement, with its high levels of nitrogen, is commonly mined for fertilizer, said Donald McFarlane, a cave ecologist at the Claremont Colleges’ W. M. Keck Science Department in California, not involved in the research. “Many of the deposits have been destroyed.” Bat guano builds up over time thanks to roosting bats. Like ice cores and tree rings, it can provide a record of past environmental conditions. That’s because guano reflects the plants, water, and insects that bats consume, the chemistry of which can shift with chang- ing climatic conditions. Roughly 3,000 ­insect-, ­nectar-, and fruit-­ ​ ­eating bats occupy Home Away from Home Cave, a census conducted in ­2008-​­2009 revealed. (The bat population in Schwallen- burgh Cave hasn’t yet been surveyed.) A single bat excretes about 20 ­millimeter-scale​­ pellets of feces each day, and a colony’s cumulative production of guano can be downright prodi- gious: Bracken Cave, in Texas, contains piles of guano topping 17 meters.

Scooping and Bagging Bat guano from Jamaica’s Home Away from Home Cave reveals a long history of environmental and agricultural In both Schwallenburgh Cave and Home Away changes. Credit: Christopher Grooms from Home Cave, the researchers used a metal tray to scoop out roughly ­1-centimeter-​­ ​ ­thick layers of guano, which they then bagged

ce cores and tree rings are natural record peled tens of meters into each underground keepers. Now researchers have used a world. “It’s straight down,” team member Icomplementary but potentially stinkier Stefan Stewart, founder of the Jamaican Caves That’s when the real fun data set—bat guano—to peer into the past. Organisation, said of one cave. After analyzing bits of pollen in excrement Bogdanowicz and his colleagues visited began: The team put on found in two caves in Jamaica, scientists Schwallenburgh Cave in northern Jamaica and climbing gear and rappeled believe they’ve pinpointed changes in agri- Home Away from Home Cave in the interior cultural production and hurricane activity. of the island. Both caves have been explored tens of meters into each only a handful of times because they’re so underground world. Into the Depths remote and require technical climbing equip- Twice in 2012, Wieslaw Bogdanowicz, a zoolo- ment, said Stewart. gist at the Polish Academy of Sciences, and his colleagues met in Jamaica. Each time, they Inaccessibility Makes Good Evidence loaded up with spelunking equipment and The relative inaccessibility of these two sub- individually. They collected roughly 80 bags hiked for hours through ­jungle-​­like terrain to terranean systems is a boon to science. It from Schwallenburgh and 130 bags from reach two caves. That’s when the real fun ensures that their extensive deposits of bat Home Away from Home. It was a sizable haul began: The team put on climbing gear and rap- guano—measuring over 120 centimeters of guano in total, Bogdanowicz said. “We had something like 20 kilograms of guano from each cave.” Back in the laboratory, Bogdanowicz and his u Read the latest news at Eos.org colleagues age dated 20 layers of guano from Schwallenburgh Cave and 28 layers from Home Away from Home Cave using a combi-

12 Eos // JANUARY 2021 NEWS

“We had something like Wildfires Threaten West Coast’s 20 kilograms of guano from each cave.” Seismic Network

s climate change increases the threat of wildfires, U.S. states are battling nation of 14C dating and 210Pb dating. They A historic blazes. On the West Coast, interpolated between the dated guano depos- the fires have put at risk several hundred its to construct an age curve for each cave. seismic stations tasked with protecting citi- Schwallenburgh Cave’s deepest guano zens from the effects of earthquakes—non- deposits were excreted roughly 200 years ago, seasonal but ever present scourges. the scientists found, and Home Away from The network of seismic stations informs Home Cave’s deposits traced back roughly ShakeAlert, an earthquake ­early-​­warning 4,300 years. (Jamaica’s first human inhabi- system designed to give people enough time tants, the Taino, arrived on the island about to drop, cover, and hold on before an earth- 2,500 years ago.) quake’s waves roll through. Eliminating sta- tions risks slowing these alerts. A solar powered seismic station (station code SALT) Hints of Hurricanes “There is no one person tracking all seis- was installed by the Pacific Northwest Seismic Net- Bogdanowicz and his collaborators used a mic stations that may be affected by the work as part of its earthquake ­early-​­warning system. microscope to examine pollen grains and fires,” said Kasey Aderhold, a seismologist This station successfully withstood one of the recent fungal spores within the guano. They found with the Incorporated Research Institutions wildfires that burned through Oregon, thanks tofire- ­ ​ evidence of deciduous trees, shrubs, grasses, for Seismology (IRIS). Instead, several orga- ­armoring installation techniques, and it continues to and cultivated crops like citrus, coffee, and nizations oversee subsets of the network, transmit data. Credit: Sara Meyer cacao. This palynological record tracks agri- monitoring the health of their charges by cultural changes, the researchers proposed. watching ­real-​­time data streams. “If data For instance, a decrease in coffee pollen in the [are] coming in,” Aderhold said, “we are early 19th century reflects decreased coffee good. If the data connection flatlines, we see what the details are.” However, sending production, a change most likely linked to investigate.” field personnel into hazardous situations like international trade being reduced by the a wildfire, especially in the COVID-19­ era, is Napoleonic Wars (1799-­ ​­1815), Bogdanowicz Vulnerabilities not a good option, explained Bodin. and his team suggested. Wildfires attack seismic stations directly and Guano can also imprint environmental indirectly by excising them from the rest of Fewer Stations, Less Coverage changes like hurricane activity, the research- the network. The sensors and electronics that “Sometimes stations are set up to daisy-­ ​ ers proposed. Bogdanowicz and his collabo- record the quakes often withstand direct ­chain or ­wheel-and-​­ spoke​­ back to a commu- rators measured a large uptick in mangrove assaults, although Paul Bodin, a seismologist nication hub, often through ­low-​­cost radio pollen in the early 19th century, a change they and network manager of the Pacific North- connections,” explained Aderhold. “If a key attributed to two known hurricanes in 1804 west Seismic Network, noted that “if a fire data connection is severed...then it can be that likely transported coastal vegetation wants to eat your station, it’ll find a way to eat problematic for seismic monitoring.” inland. The scientists also noted similar your station.” In 2015, this scenario played out in Califor- increases in mangrove pollen that they sug- Often, the stations’ most vulnerable hard- nia’s Butte Fire, where, in addition to burned gested are due to hurricanes known to have ware—communications and power—may stations, a swath of stations lost their hub, occurred in 1903, 1909, 1935, 1951, and 1988, end up scorched. For example, newer stations said Corinne ­Layland-Bachmann,​­ a seismol- they reported in Quaternary International (bit​ have solar panels necessarily exposed to ogist at Lawrence Berkeley National Labora- .ly/­guano​-­deposit). both sky and flame. Fire disables these sta- tory. Shortly thereafter, at the request of the These findings are intriguing but should be tions until repairs can commence, explained U.S. Geological Survey, ­Layland-​­Bachmann taken with a grain of salt, said Bogdan Onac, Peggy Hellweg, an operations manager at the calculated how the loss of these stations a paleoclimatologist at the University of Berkeley Seismological Laboratory. affected the health of the seismic network South Florida in Tampa not involved in the When wildfire indirectly incapacitates sta- using a ­probability-based​­ method that deter- research. That’s because other events, like tions, “the telemetry is particularly fragile,” mines whether the network can detect small fields being cleared for agriculture or large said Bodin. Telemetry refers to instruments earthquakes. She concluded that by lancing fires, can also manifest as changes in pollen, that determine how stations communicate these 28 stations from the network, the fire he said. Conclusively pinning the blame on data in real time—by Ethernet, satellite, cell, hurricanes might be premature, said Onac. or radio. Fires can cause cell tower outages, “It’s a little bit tricky just based on pollen to temporarily decommissioning any connected really, really be sure that’s the case.” stations by amputating the data feed. In such a scenario, stations typically come back “If a fire wants to eat online when power is restored. your station, it’ll find a way By Katherine Kornei (@KatherineKornei), If an off-­ line​­ station doesn’t reappear in the Science­ Writer data stream, said Hellweg, “we have to visit to to eat your station.”

SCIENCE NEWS BY AGU // Eos.org 13 NEWS

California, however, hosts fires that reg- ularly cross active faults blanketed in dense instrumentation. “Every station missing in the network is a problem for earthquake ­early-warning​­ [systems] because it will take longer to detect an earthquake with fewer stations,” said Hellweg. She argued that even small, undetected earthquakes matter. “Every measurement we make of an earth- quake brings us another step forward in terms of understanding how they happen, why they happen, and when they happen and will help us in our ability to forecast earth- quakes.” For now, both Bodin and Hellweg agreed that they’ve been lucky, considering the region’s historic infernos. Hellweg esti- This image shows how the magnitude of completeness, a measure of how sensitive the existing seismic network mated that five to six of the stations she is, changed after removal of 28 seismic stations (white triangles) because of wildfires. California’s state bound- manages have been burned. She said, “Sta- ary is shown by a black line. Credit: Corinne ­Layland-​­Bachmann tions from other networks in the state have also been affected.” Likewise, Bodin guessed that between two and 10 stations of the sev- eral hundred under his watch have been noticeably decreased the network’s ability Washington, fires tend to rage in the east, affected by fire. “It’s a dynamic situation,” to detect tiny temblors, particularly in the which is less seismically active. Also, when he said. ­wildfire-​­affected region. stations receive upgrades, they “are armored For the Pacific Northwest, Bodin said, “I’m against fire.” For example, replacing trees not worried about earthquake early warning and shrubs that abut stations with gravel By Alka Tripathy-­ ​­Lang (@DrAlkaTrip), Science and fires at this point.” He explained that in removes fuel for encroaching fires. Writer Read it first on .org Articles are published on Eos.org before they appear in the magazine. Visit Eos.org daily for the latest news and perspectives.

Advancing AI for Earth Science: A Data Systems Perspective bit.ly/Eos-AI-data Reaching Consensus on Assessments of Ocean Acidification Trends bit.ly/Eos-ocean-acidification Making a Place for the Next Generation of Geoscientists bit.ly/Eos-next-gen On Thin Ice: Tiger Stripes on Enceladus bit.ly/Eos-tiger-stripes Can Climate Preparedness Mitigate Emerging Pandemics? bit.ly/Eos-climate-pandemics

14 Eos // JANUARY 2021 OPINION

#GeoGRExit: Why Geosciences Programs Are Dropping the GRE

way to improve diversity in geoscience grad- uate programs is to drop the GRE requirement for graduate admissions.

Why #GRExit? First, “the GRE does not test the skill set and knowledge base to be a strong scientist,” Shirley Malcom, director of education and human resources programs at the American Association for the Advancement of Science, told us recently. “Nor does it test the ability to form strong research questions, conduct research, and synthesize results for con- sumption by other scientists and the public.” Like other standardized tests, the GRE mostly tests a person’s ability to take a standardized test. Several studies have shown that perfor- mance on the GRE is a poor predictor of grad- uate degree success across fields. For exam- ple, researchers tracked more than 1,800 doctoral students in STEM fields and found little correlation between GRE scores and degree completion. In fact, men with the low- est GRE scores finished their doctoral pro- grams more frequently than those with the lot has changed recently in higher show that it is not an accurate predictor of highest scores [Petersen et al., 2018]. Moneta-​ education. Amid the ongoing pan- graduate school success, that scores are com- Koehler­ et al. [2017] found that the GRE did not A demic caused by ­COVID-​­19, univer- monly misused and misinterpreted by admis- assess skills and fortitude for biomedical sities and graduate schools have adapted sions committees, and that the test is biased graduate programs: GRE scores had no pre- their instruction and research activities against women compared with men and dictive capabilities for who would graduate, and have faced declining revenues. These against people of color compared with white pass qualifying exams, publish more papers, changes were forced upon programs by and Asian people [Miller and Stassun, 2014]. and obtain grants, or for any other measure necessity, and they, along with negative The burden of taking the test, and the impact of success. impacts on many students from the pan- of low scores, limits access to graduate school Second, the GRE poses a significant finan- demic, may continue affecting higher edu- for underrepresented groups [Miller et al., cial burden to economically disadvantaged cation in the near future by, for example, 2019]. decreasing application numbers. To bolster The geosciences are some of the least admissions, some graduate programs are diverse science, technology, engineering, and temporarily dropping the Graduate Record mathematics (STEM) fields, especially at Examinations (GRE) as an admissions higher levels. More than 90% of geoscience “The GRE does not test requirement. However, dropping the GRE doctoral degrees in the United States are the skill set and altogether, as a step toward equity and inclu- awarded to white people, and there has been sivity in graduate admissions and education, no significant change in 40 years [Bernard and knowledge base to be has been a longer-­ ​­term battle, with many Cooperdock, 2018]. Structural and social bar- a strong scientist.” calling it #GRExit on social media. riers result in undergraduate and graduate The GRE is a standardized test used widely students from underrepresented back- since the 1950s as a requirement for U.S. and grounds leaving the field, which compounds Canadian graduate admissions. The earliest the lack of diversity at the faculty level. The versions of the GRE were first tested on stu- lack of diversity and inclusion hurts the geo- students. As of 2020, the test cost $205 to dents at Harvard, Yale, Princeton, and Colum- sciences, excluding voices that can help solve take and $27 for each official score sent to an bia in 1936, 3 decades before those univer­ Earth’s most critical problems. Geoscience institution to which a student applies. GRE sities became fully coed, with the test faculty must understand, acknowledge, and books are an additional expense, and prepa- standardized by 1949. The test was over- address individual and institutional biases ration courses can cost thousands of dollars.

CC0 1.0 (bit.ly/cco1-0) Brodie Vissers, CC0 1.0 hauled in 2011, but research continues to to improve inclusion in our field. One simple On top of these costs, lost wages from taking

SCIENCE NEWS BY AGU // Eos.org 15 OPINION

time off to travel to a testing center or attend ment of Geosciences, the number of applica- successful indicator of student success in classes, plus paying for childcare during this tions increased substantially in the first graduate school. time, put an overwhelming burden on eco- applicant pool after the department dropped Second, prepare for pushback. Many fac- nomically disadvantaged students. the GRE requirement in 2019. Across the mul- ulty have been using the GRE as an admis- Third, the GRE has been shown to effec- tiple doctoral programs administered by the sions metric for years without considering tively predict sex and race. Petersen et al. department, the total number of applicants how it is removing strong candidates from [2018] showed that there was “a significant was more than double the previous maximum their pool. Strike up conversations with gender effect” in GRE quantitative (Q) and more than 4 times the number from the these faculty informally to get a sense of scores: Men averaged far higher scores than previous year. After the GRE was dropped, their position, so you know where you are women, but no significant gender differ- initial offers for admission and funding were starting. Encourage dialogue among faculty ences were seen in any other measure of suc- balanced across gender. to provide opportunities to catalog concerns cess, including degree completion percent- In the Georgia Institute of Technology’s about changes in admissions processes and age. Further, Miller and Stassun [2014] showed (Georgia Tech) School of Earth and Atmo- evaluate whether those concerns are borne that applicants from underrepresented spheric Sciences, the percentage of graduate out by data. groups also scored far lower than white and applicants from underrepresented groups Third, do your homework with the univer- Asian people—for example, 82% of white increased from a low within the past 8 years sity as a whole. Find out whether other pro- and Asian applicants scored above 700 on of 6% to 13% in 2020, the first applicant pool grams at your university have dropped the the GRE Q, but only 5.2% of minoritized after the program dropped its GRE require- GRE; if so, they may already have built a applicants did—meaning that if GRE scores ment. Of the applicants accepted in spring framework that could save your department provided an arbitrary cutoff for admissions, 2020, 23% were from underrepresented time and effort. You should be aware of your many underrepresented students, Asian groups, compared with 5%-18%​­ over the pre- university’s broader requirements for grad- women, and white women would not even be vious 8 years. uate admissions as well: Some schools have considered. dropped the GRE from consideration for Advice on How to #GeoGRExit ­department-​­level admissions while still The #GRExit Movement Grows Here we present some tips on how to requiring it for the university application and In response to the shortcomings listed approach the #GeoGRExit process from fac- thus still imposing financial burdens on above, the ­2019-​­2020 academic year saw a ulty whose departments successfully dropped applicants. (Temporary changes in admis- major increase in geosciences programs the GRE. sions processes made by schools during the dropping the GRE from admission require- First, arm yourself with data. Knowing and current pandemic might spur effective ments: From May to December 2019, the sharing the ample, peer-­ ​­reviewed literature pushes for permanent ­university-​­wide number of geosciences programs that about the inequalities inherent in the test changes in GRE requirements, although that dropped the GRE or made it optional rose with faculty have been an important approach remains to be seen.) It is also important to from 0 to 30, and as of early November 2020 check whether the GRE is required for other that figure had risen to more than 90. The elements within the application process, such movement to remove the GRE requirement as fellowships. for graduate school admissions started in the life sciences. The geosciences movement Knowing and sharing the A Better Measure of Applicants built on the bioscience #GRExit movement ample, ­peer-​­reviewed The graduate admissions process should and a crowdsourced database of programs move away from numerical rankings of stu- that have abandoned the GRE. In September literature about the dents to more holistic evaluations of entire 2019, lead author Sarah Ledford created a inequalities inherent in applications. Graduate programs need to similar #GeoGRExit database of programs clearly articulate what skills are required of no longer requiring the GRE, which students the test with faculty have applicants and use those as criteria for admis- can reference when applying to graduate been an important sions. It is essential to remember that grad- school. uate students are trainees and will gain most Spring 2020 marked the first round of approach in convincing of their research and technical skills in grad- applications after many geosciences pro- departments to drop the uate school and beyond. grams dropped the GRE requirement. ­Long-​ The overarching concept of holistic ­term monitoring of applicants and accep- requirement. review, which emphasizes assessment of tances will be necessary to determine whether noncognitive skills, is receiving increased removing the GRE changes the numbers of attention from graduate administrators minorities and white women in geosciences [Kent and McCarthy, 2016]. Graduate pro- graduate programs and whether removing grams have the opportunity to base deci- the GRE affects student success rates. in convincing departments to drop the sions on assessments of skills and character Initial anecdotal evidence indicates that requirement. Prior to the successful faculty attributes “such as drive, diligence, and the graduate programs that removed the GRE vote to drop the GRE by Georgia Tech’s School willingness to take scientific risks,” as Miller requirement had higher overall numbers of of Earth and Atmospheric Sciences, coauthor and Stassun [2014, p. 303] put it, which applicants, as well as higher percentages of Kim Cobb gave a presentation to her col- research has shown are more predictive of underrepresented applicants and accep- leagues about compiled research on estab- future success in STEM workforces than GRE tances. In Boise State University’s Depart- lished biases in the GRE and how it is not a scores are.

16 Eos // JANUARY 2021 OPINION

There are no guidelines yet for what exactly Faulkes, Z. (2019), #GRExit’s unintended consequences, Sci- Implicit biases will ence, 363(6425), ­356–​­356, https://­doi​.org/­10​.1126/­science​ programs should include in holistic reviews, .aaw1012. but interviews with applicants would be very continue to hamper the Kent, J. D., and M. T. McCarthy (2016), Holistic review in gradu- telling, as noted in the 2016 “Holistic Review ate admissions, Counc. of Grad. Sch., Washington, D.C., cgs- progress of minorities in net​.org/­ckfinder/­userfiles/­files/CGS_HolisticReview_final_web​ in Graduate Admissions” report. Other .pdf. applications criteria, like grade point average STEM. As an outdated, Miller, C., and K. Stassun (2014), A test that fails, Nature, 510(7504), ­303–​­304, https://­doi​.org/­10​.1038/­nj7504​-​­303a. and letters of reference, should also be con- expensive, and biased Miller, C. W., et al. (2019), Typical physics Ph.D. admissions crite- sidered, but they can be susceptible to pit- ria limit access to underrepresented groups but fail to predict falls. Grade point average and institutional test, the GRE exacerbates doctoral completion, Sci. Adv., 5(1), eaat7550, https://­doi​.org/­ 10​.1126/­sciadv​.aat7550. prestige are often unconsciously weighted such biases. ­Moneta-​­Koehler, L., et al. (2017), The limitations of the GRE more than is warranted. Overreliance on ref- in predicting success in biomedical graduate school, PLoS erence letters is also problematic; many of ONE, 12(1), e0166742, https://doi­ .org/​ 10­ .1371/​ journal­ .pone​ ​ .0166742. the gatekeeping techniques that hinder Petersen, S. L., et al. (2018), ­Multi-​­institutional study of GRE equity and diversity are strongly reflected scores as predictors of STEM Ph.D. degree completion: GRE gets a low mark, PLoS ONE, 13(10), e0206570, https://­doi​.org/­ in reference letters [Faulkes, 2019]. We ably threatens scientific progress. Given the 10​.1371/­journal​.pone​.0206570. acknowledge that not every program has interdisciplinary and synthetic nature of time to interview every graduate student Earth science subdisciplines like climate and candidate, but as with job interviews, time critical zone science, placing emphasis on By Sarah H. Ledford (sledford@gsu​.edu), spent interviewing a short list of prospective noncognitive skills has the potential to Georgia State University, Atlanta; Minda M. students will result in selection of stronger enhance diversity, inclusion, and access in Monteagudo, Georgia Institute of Technology, candidates. the field while accelerating scientific discov- Atlanta; Alejandro N. Flores, Boise State Uni- Implicit biases will continue to hamper the ery and innovation. versity, Boise, Idaho; and Jennifer B. Glass and progress of underrepresented students in Kim M. Cobb, Georgia Institute of Technology, STEM. As an outdated, expensive, and biased References Atlanta test, the GRE exacerbates such biases. Not only is it irrelevant for American higher edu- Bernard, R. E., and E. H. Cooperdock (2018), No progress on u diversity in 40 years, Nat. Geosci., 11, ­292–​­295, https://­doi​ Read the article at bit​.ly/­Eos​ cation in the 21st century, but also it argu- .org/­10​.1038/­s41561​-­018​-­0116​-­6. -­GeoGRExit

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SCIENCE NEWS BY AGU // Eos.org 17 © Nic Lehoux

18 Eos // JANUARY 2021 Climate change will exacerbate the food, energy, water, health, and equity challenges that urban communities face, but cities also have opportunities to improve sustainability and outcomes.

BY DONALD J. WUEBBLES, ASHISH SHARMA, AMY ANDO, LEI ZHAO, AND CAROLEE RIGSBEE © Nic Lehoux

SCIENCE NEWS BY AGU // Eos.org 19 Cities like Chicago, seen here, must take a holistic approach that combines social and political considerations with scientific and engineering approaches to produce work- able strategies for dealing with the complex, interacting effects of climate change Credit: Buphoff, CCBY- ­ ​­SA 3.0 (bit​.ly/­ccbysa3​-­0)

limate change is imposing [U.S. Global Change Research Program, 2017]. complex, interacting effects on Under a ­high-emissions​­ scenario called every ecosystem around the RCP 8.5 (Representative Concentration world, and of course, there is Pathway 8.5), a combination of sea level rise more change to come. Prob- There is a need and the increasing intensity and frequency lems associated with heat of extreme weather may make many cities stress, food availability, energy security, air to connect nearly uninhabitable by the end of this cen- Cquality, water quality and availability, flood- tury. sustainability ing, and sea level rise affect even the most Recent unprecedented losses in equity, remote areas, but these issues are amplified science more health, and life have exposed gaps in our in urban areas [Grimm et al., 2008], where fully with efforts readiness to cope with ­climate-​­related many people already disproportionately extremes today and our unpreparedness to experience disparities in health and eco- to address equity face them in the future. Thus, there is a nomic and political equity [Tessum et al., pressing need for convergent research that 2019]. and justice issues investigates paths toward urban sustain- Continuing rapid urban development will and with the many ability. Many cities, including Barcelona, only intensify these disparities unless mea- Chicago, New York, Paris, and Seattle, are sures are taken to ameliorate them. At the sectors that make attempting to increase sustainability same time, cities face additional stresses up urban environs. through climate action plans that map out from ongoing and projected climate change steps to reduce emissions.

20 Eos // JANUARY 2021 We see the urban metabolism However, there is a need for research that ­sustainability-​­related strategies and actions feeds into these plans to connect sustain- must be carefully orchestrated because their framework ability science more fully with efforts to effectiveness depends on combinations of as essential address equity and justice issues and with social, economic, health, and climate condi- the many sectors—such as infrastructure, tions. for studying energy, and transportation—that make up Strategies can also have complex socio- the complex urban environs. Such efforts should aim to ecological trade-­ offs​­ [Cao et al., 2016; design multidisciplinary and multistake- Sharma et al., 2018] and may trigger unin- interactions holder networks that can collectively copro- tended climatic and socioeconomic conse- duce knowledge and information to deliver quences [Zhao et al., 2017]. For example, among people, actionable ­research-​­based solutions and models indicate that ­large-​­scale imple- constructed informed ­decision-​­making to the problems mentation of cool roofs designed to reflect that communities of many sizes face (Fig- more sunlight than conventional roofs may infrastructure, ure 1). We now have a ­time-​­sensitive oppor- reduce precipitation in urban areas [Geor- and surrounding tunity to achieve such a vision for the gescu et al., 2014], potentially exacerbating coproduction of knowledge, forming ­public-​ water stress. Green infrastructure, which natural systems in ­private-​­community partnerships with the relies on plants to manage water runoff and purpose of attaining the United Nations filter and cool the air, may require irriga- cities of all sizes. 2030 Agenda for Sustainable Development. tion and should be sited carefully. In ­dry-​ ­climate cities where water is already INTERACTING SYSTEMS, ​ scarce—and becomes scarcer in the pro- UNINTENDED CONSEQUENCES jected future under climate change [Zhao Considerable efforts have been invested in et al., 2017]—green infrastructure’s inter- devising ­infrastructure-​­based schemes for action with and effects on climate change climate adaptation and advancing urban are poorly understood. cies within municipal governments. How- sustainability [Rosenzweig et al., 2009; Traditionally, urban planning concen- ever, in recent decades, there has been a Sharma et al., 2016; Zhao, 2018]. However, trated on ­top-​­down interventions by agen- push to create more interdisciplinary knowledge that considers a broader range of potential impacts. As part of this push, urban planning has seen a recent influx of Urban Sustainability “smart city” approaches that view cities as mechanistic systems composed of discrete components to be optimized individually. However, cities cannot achieve sustainabil- ity without a holistic view of the interde- pendencies among essential human needs Climate (food, energy, and water); constructed urban infrastructure; associated natural systems (air, water, land, ecosystems); and social, political, and legal decisions span- ning all relevant scales (individuals, neigh- borhoods, municipalities, regions, nations). For example, national policy can limit or enhance what is doable within a Urban city. At the local scale, residents of a single Convergence neighborhood can delay projects by tying Research them up in litigation. Inadequate consider- ation of these interdependencies can thus Health and Equity result in unintended social stresses, espe- Centric Solutions cially for the poor. Urban metabolisms, which consider the flows of materials and energy within a city Multidisciplinary Knowledge Multi-Stakeholder Engagements and which comprise subsystems related to Co-production food, energy, and water, are a concept that Engineering of Knowledge Non-governmental organizations (NGOs) Natural Sciences Private and Business Sector takes such a holistic view. These subsys- Social Sciences Municipalities tems and their associated climate chal- Arts and Humanities Urban communities lenges have been studied for several decades, but relationships among subsys- tems are often obscured by the ­discipline-​ Fig. 1. This conceptual framework outlines a multidisciplinary, multistakeholder approach to urban sustainability. ­bound approach of past research. We see

SCIENCE NEWS BY AGU // Eos.org 21 Making science

more relatable to NEEDED: MULTIDISCIPLINARY, Each of these pathways can be vital in the public may lead MULTISTAKEHOLDER RESEARCH engaging policymakers, voters, and other Contemporary urban sustainability research community members in responding to to more community requires a broad multidisciplinary method- environmental threats and participating in involvement in ology. Yet such research is challenging and urban sustainability solutions. They can also therefore understandably uncommon. lead to important insights into urban sys- planning for futures Engineers, social scientists, ecologists, and tems over a wide range of geographical and experts in the arts and humanities speak temporal scales (daily, seasonal, and long that consider local different disciplinary languages and term), from the neighborhood to the histories. approach the analysis of data from urban metropolis and beyond. environments in different ways [ Jacobs, Multidisciplinary approaches also sup- 2014]. Their models, data sets, and findings port deep, bidirectional engagement with are not easily coupled and integrated, community stakeholders that leads to meaning that potentially valuable urban improved understanding of stakeholder tools and insights remain undeveloped. concerns and priorities and to collabora- However, ­system-​­level solutions can be tions with players critical to delivering solu- better designed and produce fewer unin- tions. Communities of different sizes the urban metabolism framework as being tended consequences if we explore issues require different solutions depending on an essential conceptual and quantitative that lie at the intersections and boundaries their resources, capabilities, and priorities. model for studying the complex interactions of the natural sciences, engineering, human- Community groups and municipal leaders among people, constructed infrastructure, ities, social sciences, arts, and other disci- have direct understanding of pressing local and surrounding natural systems in cities of plines. For example, such a holistic approach problems and of the municipal settings in all sizes. might have alerted Los Angeles city planners which solutions must be implemented. Generally, urban sustainability research to the distressingly high costs to building Individuals and enterprises in business, is focused on very large urban systems. owners associated with a 2013 law requiring especially those that combine social, cul- However, billions of people live in smaller that all buildings install cool roofs. tural, and environmental issues, referred to communities, and although cities of vary- More specifically, the arts, humanities, as social entrepreneurship, are also key to ing sizes face many of the same problems and social sciences offer important pathways the success of sustainability solutions. amid climate change, a single solution for a to and lessons for understanding urban sus- Beyond providing insight into finance and given problem is unlikely to fit for all. tainability that complement those typically feasibility issues, they can help drive the Instead, cities require sustainability solu- followed by the natural sciences and engi- design, development, and delivery of scal- tions involving infrastructure, technology, neering fields [Pykett et al., 2020]. For exam- able solutions. Moreover, nongovernmental policy, and management that are tailored ple, ­community-​­based and participatory organizations often have extensive experi- to their own vulnerable systems. This research methods can identify ­climate-​ ence working with multiple stakeholders to inclusiveness in research and planning will ­related infrastructure, equity, and health effect environmental change, albeit some- help improve the lives of people in less risks associated with food, energy, and water times with a limited focus on urban sustain- densely populated areas that are often needs. These methods can also help project ability that lacks a convergent multidimen- neglected in conversations about sustain- future problems for residents of small and sional approach. ability. poor communities that are generally not Understanding the impacts of urban sys- represented in municipal ­decision-​­making. TOWARD CONVERGENT​ tems on the environment at local to global Making science more relatable to the URBAN SUSTAINABILITY SCIENCES scales also requires considering complex public may lead to more community Knowledge gaps in convergent urban sus- and interdependent social and physical involvement in planning for futures that tainability research can be narrowed by factors, which can be studied using consider local histories. In many cities, pub- focusing on cities as complex, multiscale, increasingly sophisticated models. Despite lic history, heritage studies, and museum interdependent, and adaptive systems with advances in computing, however, many studies contribute to sustainability research active interactions among social, natural, knowledge gaps still exist. These gaps through their connections with local people, and engineered systems. Such an approach involve both spatial and temporal scales, past and present. should include local stakeholders, busi- the need for improved data sets about Communicating in ways that can over- nesses, and communities. Toward this end, urban land use, and the need for better and come science and engineering language we propose a strategy for constructing more detailed measurements of complex barriers and that use culturally meaningful urban research networks for convergent urban flows (e.g., meteorology, air quality, framing is useful in relating traditions and urban sustainability science that are combined sewage outflows, mobility). lifestyles to current and future sustainabil- equally relevant for cities of all sizes (Fig- These gaps prevent adequate estimates of ity challenges in communities. Such ure 2). the flows of energy and matter in urban approaches can focus on community priori- Now is the time for collaborations and systems [Sharma et al., 2020]. More invest- ties and concerns shared through cultural partnerships spanning research disciplines, ments in focused scientific and engineer- traditions in art, poetry, storytelling, music, the private and nonprofit sectors, and rep- ing research could provide needed perspec- or culinary arts and on using history to resentatives from municipalities to define tive on urban woes and potential solutions teach lessons about how people cause or holistic pathways forward to tackle critical across scales. adapt to environmental changes. urban sustainability challenges facing cities

22 Eos // JANUARY 2021 of all sizes. Interactive planning and ­decision-​­making processes already exist, PRIORITIZE AND DIAGNOSE SUSTAINABILITY CHALLENGES but they require additional multidisciplinary Identify and prioritize critical problems for each urban sustainability and ­cross-​­disciplinary interactions to be challenge or stressor in a city (e.g., water, energy, climate) with local fully successful. stakeholder participation Investments in multidisciplinary and Identify critical causes impacts of each challenge multistakeholder convergent research can Identify lever points (e.g., policy, technology, behavior) for e ecting guide urban innovations and advance sus- change (causes or e ects) tainability on multiple fronts, both locally and globally. Together we can close the gaps between the diagnosis of ­climate-​­related UNDERSTAND ACTORS AND ORGANIZATIONS urban challenges and the identification and Identify how di erent types of actors and organizational factors influence implementation of appropriate solutions the causes and impacts of urban stressors and partnerships that account for commu- Distinguish between facilitators of and barriers to change nity concerns about health and equity and that are needed to ensure more sustainable  food, energy, and water futures for our cit- CONCRETE PATHWAYS TO SUSTAINABILITY ies. Identify promising solutions for urban stressors with the help of multidis- ciplinary scientific knowledge and expertise ACKNOWLEDGMENTS This article is an outcome of the 2019 CURES  Connections Workshop: New Voices and CHOOSE ACTIONS THAT WORK TOWARD SUSTAINABILITY Paths to Urban Sustainability, supported by Identify and prioritize actions, projects to undertake, and deliverables National Science Foundation grant 1929856 (e.g., papers, pilot projects, feasibility studies) to explore concepts for advancing sustain- able urban systems research networks. We thank the more than 125 diverse workshop  IDENTIFY STEPS THAT SUPPORT SUSTAINABILITY ACTIONS participants. We especially acknowledge the Identify resources available and needed, including key technology, point contributions of ­Anne-​­Marie Hanson of the people, institutional and funding sources, and other collaborators University of Illinois at Springfield and Eliz- abeth Kocs, Cynthia ­Klein-​­Banai, Dean Identify issues, concerns, and barriers that must be overcome Massey, and Moira Zellner of the University  of Illinois at Chicago. CONSTRUCT THE NETWORK FOR SUSTAINED PROGRESS REFERENCES Define ways to ensure regular and e ective collaboration among teams Cao, C., et al. (2016), Urban heat islands in China enhanced Set initial deadlines and goals by haze pollution, Nat. Commun., 7, 12509, https://­doi​.org/­10​ .1038/­ncomms12509. Identify point people for each project to ensure work continues Georgescu, M., et al. (2014), Urban adaptation can roll back  warming of emerging megapolitan regions, Proc. Natl. Acad. Sci. U. S. A., 111(8), 2,­909–2,914, https://­doi​.org/­10​.1073/­pnas​ .1322280111. Grimm, N. B., et al. (2008), Global change and the ecology of cities, Science, 319(5864), ­756–​­760, https://­doi​.org/­10​ Fig. 2. Following the steps in this flowchart can help lead to convergent urban research. .1126/­science​.1150195. Jacobs, J. A. (2014), In Defense of Disciplines: Interdisciplinarity and Specialization in the Research University, 288 pp., Univ. of Chicago Press, Chicago, Ill., ­press​.uchicago​.edu/­ucp/­books/­ book/­chicago/­I/­bo16468807​.html. Tessum, C. W., et al. (2019), Inequity in consumption of goods Ashish Sharma, Climate and Atmospheric Pykett, J., et al. (2020), Developing a citizen social science and services adds to ­racial-​­ethnic disparities in air pollution approach to understand urban stress and promote wellbeing exposure, Proc. Natl. Acad. Sci. U. S. A., 116(13), 6,­001–​­6,006, Science Section, Illinois State Water Survey, in urban communities, Palgrave Commun., 6, 85, https://­doi​ https://­doi​.org/­10​.1073/­pnas​.1818859116. .org/­10​.1057/­s41599​-­020​-­0460​-­1. Prairie Research Institute, Champaign; also at U.S. Global Change Research Program (2017), Climate Science Department of Atmospheric Sciences, Univer- Rosenzweig, C., et al. (2009), Mitigating New York City’s heat Special Report: Fourth National Climate Assessment, vol. 1, island: Integrating stakeholder perspectives and scientific edited by D. J. Wuebbles et al., 475 pp., Washington, D.C. sity of Illinois at Urbana-­ Champaign,​­ Urbana; evaluation, Bull. Am. Meteorol. Soc., 90(9), 1,­297–​­1,312, https://­ doi​.org/­10​.1175/­2009BAMS2308​.1. Zhao, L. (2018), Urban growth and climate adaptation, Nat. Clim. Amy Ando, Department of Agricultural and Change, 8, 1034, https://­doi​.org/­10​.1038/­s41558​-­018​-­0348​-­x. Sharma, A., et al. (2016), Green and cool roofs to mitigate urban Consumer Economics, University of Illinois at heat island effects in the Chicago metropolitan area: Evalu- Zhao, L., X. Lee, and N. M. Schultz (2017), A wedge strategy Urbana-Champaign, Urbana; Lei Zhao, Depart- ation with a regional climate model, Environ. Res. Lett., 11(6), for mitigation of urban warming in future climate scenarios, 064004, https://­doi​.org/­10​.1088/­1748​-­9326/­11/­6/­064004. Atmos. Chem. Phys., 17(14), 9,­067–​­9,080, https://­doi​.org/­10​ ment of Civil and Environmental Engineering, .5194/­acp​-­17​-­9067​-­2017. Sharma, A., et al. (2018), Role of green roofs in reducing heat University of Illinois at Urbana-Champaign, stress in vulnerable urban communities—A multidisciplinary Urbana; and Carolee Rigsbee, Department of approach, Environ. Res. Lett., 13(9), 094011, https://­doi​.org/­10​ .1088/­1748​-­9326/­aad93c. AUTHOR INFORMATION Management, University of Illinois at Springfield Sharma, A., et al. (2020), ­Urban-​­scale processes in high-­ ​­spatial Donald J. Wuebbles ([email protected]),​ ­resolution Earth system models (ESMs), Bull. Am. Meteorol. u Soc., 101(9), ­E1555–​­E1561, https://­doi​.org/­10​.1175/­BAMS​-­D​-­20​ Department of Atmospheric Sciences, Univer- Read the article at bit​.ly/­Eos​ -­0114​.1. sity of Illinois at ­Urbana-​­Champaign, Urbana; -­sustainable​-­cities

SCIENCE NEWS BY AGU // Eos.org 23 24 Eos // JANUARY 2021 Habitability and the Evolution of Life Under Our Magnetic Shield

Earth’s global magnetic field likely dates back billions of years and is a barrier against cosmic radiation. What roles has it played?

By Manasvi Lingam

Auntspray/Depositphotos.com

SCIENCE NEWS BY AGU // Eos.org 25 arth’s magnetic field, in some Much about Earth’s planetary magnetism, ineffable respects, is reminiscent however, remains poorly understood. Of the of the exquisite poem attributed to multifarious questions that spring to mind, the semihistorical Buddhist monk two stand out: When and how did Earth’s Budai (sometimes referred to as dynamo originate and evolve over time? And EHotei), considered by some to be an incar- what are the consequences of a magnetic nation of the future Buddha, Maitreya: field for habitability and life? Both questions span rapidly evolving research domains and Maitreya! Maitreya! touch upon many interconnected and subtle Forever dividing himself, scientific issues. Hence, the discussion of He’s here, there, everywhere— them here, which offers an overview of Yet scarcely noticed. major points, is limited and somewhat sub- —Hotei (as translated by Lucien Stryk jective in scope [Lingam, 2019]. and Takashi Ikemoto)

The geomagnetic field similarly perme- The History of Earth’s Dynamo ates myriad aspects of life. For instance, a Certain minerals on Earth, such as magne- diverse range of organisms, from micro- tite, are particularly sensitive to the geo- scopic magnetotactic bacteria to all major magnetic field because of their ferrimag- groups of vertebrates, have evolved inge- netic nature, and measurements of their nious and intricate mechanisms to detect magnetization have enabled us to deduce the magnetic field and to use this informa- Earth’s magnetic field strength at different tion for orientation and locomotion. times in the past. The oldest evidence for a Humans, of course, have learned to use geodynamo comes from analysis of mag- the geomagnetic field in countless advanta- netic inclusions in 4.­2-​­billion-​­year-​­old zir- geous ways, with the magnetic compass and con crystals retrieved in Australia [Tarduno its associated 2,­000-​­year history as the et al., 2020], which collectively indicate that quintessential example. On the other hand, Earth’s magnetic field then may have been our dependence on electromagnetic roughly half as strong as it is today. devices means that we are highly This putative discovery raises more ques- susceptible to geomagnetic tions, including about the processes storms that perturb our responsible for the geodynamo’s genesis planet’s magnetic field, and functioning during the Hadean and The wide range with devastating eco- Archean eons (spanning 2.­5-​­4.5 billion nomic losses poten- years ago). One hypothesis, among others, of benefits stemming from tially ranging into suggests that the high temperatures pro- the trillions of dol- duced during giant impact events in this Earth’s magnetic field have been lars [Lingam and period facilitated the transport of magne- invoked to argue that a planetary Loeb, 2017]. More sium to the core, where precipitation of broadly, the mag- ­magnesium-​­containing minerals yielded magnetic field is a chief netic field generated enough energy to power the geodynamo requirement for habitability. by Earth’s dynamo [Badro et al., 2016]; however, some scientists (the geodynamo) is have critiqued this model on the grounds responsible for our that the energy produced is insufficient. It planet’s substantial mag- has also been suggested that precipitation netosphere, which is believed of silicon dioxide from the core may have to protect Earth against the dele- contributed to the sustenance of the early terious effects of the solar wind. geodynamo. The wide range of benefits stemming The nucleation (i.e., formation) of Earth’s from Earth’s magnetic field have been inner core is considered crucial in the fur- invoked by many scientists to argue that a ther evolution of the geodynamo [Smirnov planetary magnetic field is a chief require- et al., 2016], chiefly because the latent heat ment for habitability [Lammer et al., 2009]. liberated during crystallization of the inner That Mars, a planet currently sans strong core, in tandem with ongoing chemical dif- global magnetic fields, lacks a substantial ferentiation (in which materials of different atmosphere is often interpreted as a conse- compositions separate within Earth based quence of its dynamo shutting down about on density and chemical affinity), is capable 4 billion years ago, which thus subjected the of powering the geodynamo. The impor- atmosphere to erosion by the solar wind. tance of inner core nucleation (ICN) is

26 Eos // JANUARY 2021 widely recognized, but its timing is still would represent a compelling illustration of uncertain. the interplay between astrophysics and Magnetic field intensities inferred from biology. rock samples dating to the Mesoproterozoic (roughly 1–1.5​­ billion years ago) Implications of Earth’s Magnetic Shield have been argued as evidence The existence of a global magnetic field for ICN occurring in this raises questions about how it affects habit- It is tempting to interval. In contrast, ability and life. This is a question wide in analysis of magnetic scope, and the discussion here is limited to speculate about whether inclusions in crystals only a couple of salient effects. It is com- deep connections exist between the from the Ediacaran monly thought that magnetic fields are (about 565 million necessary to protect planetary atmospheres nucleation of Earth’s inner core and years ago) is com- from erosion by the solar wind, which has- patible with the tens the acceleration and escape of atmo- the increase in the strength of Earth’s onset of ICN during spheric particles through electromagnetic magnetic field on the one hand, and that time. The dis- interactions. But how valid is this premise? crepancy in the pos- Researchers have simulated the escape of the diversification of animals sible ages for the oxygen ions from Earth’s atmosphere by on the other. onset of ICN may stem adapting a model constructed for Mars, from systematic biases in finding that the escape rate could be ele- earlier paleomagnetic inten- vated by a factor of roughly 1,000 if the sity data sets due to processes magnetic field strength is extremely weak. such as viscous remanent magnetiza- However, more recent numerical models tion, which is induced in rocks with ­long-​ and analytical studies have found that the ­term exposure to magnetic fields, thereby relationship between a planet’s magnetic making measured paleomagnetic intensi- field and the escape rate of oxygen ions is ties appear higher than the actual values highly nonlinear. In particular, across a when the rocks were formed. Chemical and range of magnetic field strengths—and thermal alteration of magnetic minerals contrary to expectations—the escape rate over time can also complicate interpreta- might actually decrease when the field tions of paleomagnetic intensities. strength is weakened [Lingam and Loeb, If nucleation of Earth’s inner core 2019]. Hence, there are tentative grounds to occurred during the Ediacaran, a striking suppose that a weak or even absent geo- coincidence emerges. The Ediacaran was an magnetic field may not have been as much a unusually dynamic period on Earth, charac- hindrance to life as originally anticipated, at terized, for instance, by the intermittent least insofar as the field’s effects on atmo- oxygenation of the ocean and by rapid shifts spheric erosion by the solar wind are in evolution (especially in animals [Droser concerned. et al., 2017]). These shifts culminated in the Earth’s magnetospheric ­so-​­called Cambrian explosion, when multi- shielding acts as a protec- cellular life seemingly diversified into most tive barrier against of the lineages we recognize today. It is ­high-​­energy solar tempting to speculate about whether deep particles and galactic There are tentative connections exist between ICN and the cosmic rays (GCRs) grounds to suppose that a weak increase in the strength of Earth’s magnetic (only the latter are field on the one hand, and the diversifica- considered here, as or even absent geomagnetic field tion of animals on the other, as suggested the former are may not have been as much a by some authors. more intermittent). It has been proposed that the stronger When GCRs pass hindrance to life as originally magnetic field in the Cambrian was respon- through Earth’s anticipated. sible for shielding the atmosphere from atmosphere, they lead erosion by the solar wind, mitigating the to formation of second- flux of cosmic rays reaching the surface, and ary particles like muons preventing ozone depletion. These pro- and pions. And when GCRs cesses might have contributed to the diver- and their derivatives reach the sification of animals by reducing ­high-​ surface, they can damage biomolecules ­energy radiation and preserving oxygen like DNA. The cumulative impact of such levels. If proven correct, this paradigm radiation is measured by a quantity known

SCIENCE NEWS BY AGU // Eos.org 27 as the equivalent dose rate. With a weaker further research synthesizing magnetic field, the equivalent dose rate is knowledge from geology, anticipated to increase because a higher flux astronomy, plasma phys- of GCRs reaches the surface, and vice versa. ics, microbiology, evolu- By resolving This trend is indeed borne out by ­state-​­of-​ tionary biology, and whether Earth’s ­the-​­art numerical simulations, but the other disciplines. amplification is modest [Glassmeier and Vogt, By resolving the magnetic field played a 2010]: For an ­Earth-​­like atmosphere, the riddle of whether significant role in modulating the equivalent dose may only increase by a fac- Earth’s magnetic tor of about 2 if the geomagnetic field is field played a sig- evolution of life, we will be better absent. nificant role in Incoming ­high-​­energy particles also modulating the evo- positioned to consider whether a affect life through an indirect, but import- lution of life, we will magnetic field is necessary for a ant, avenue. They can react with the two be better positioned most abundant constituents of Earth’s to consider the related planet to be habitable in the atmosphere, forming nitrogen oxides that question of whether a first place. subsequently react with and deplete strato- magnetic field is necessary spheric ozone. Ozone depletion enhances for a planet to be habitable in the flux of UV radiation to the surface, the first place. This endeavor has which has a number of ­well-​­known delete- major implications for understanding the rious consequences for life, ranging from origins and evolution of life on Earth; for damaged biomolecules to acute physiologi- applications, such as the development of cal stress. Multiple numerical models indi- artificial magnetospheres, that could affect cate that a weakened or absent magnetic humanity’s future in many ways; and for field could result in a 20% or greater addressing that age-­ ​­old question, Are we increase in UV radiation penetrat- alone? Let us pursue this quest in all ear- ing to the surface, especially at nestness. the polar regions [Glass- Fathoming the meier and Vogt, 2010]. References Whether such a boost, Badro, J., J. Siebert, and F. Nimmo (2016), An early geodynamo driven by exsolution of mantle components from Earth’s core, magnitude and nature of which may not sound Nature, 536, 326–­ 328,​­ https://doi­ .org/​ 10­ .1038/​ nature18594.­ these repercussions necessitates like much at first Droser, M. L., L. G. Tarhan, and J. G. Gehling (2017), The rise of glance, is high animals in a changing environment: Global ecological inno- vation in the late Ediacaran, Annu. Rev. Earth Planet. Sci., 45, further research synthesizing enough to cause 593–­ 617,​­ https://doi­ .org/​ 10­ .1146/​ annurev­ -​ earth­ -​ 063016­ -​ 015645.­ widespread damage Glassmeier, K.-H.,​­ and J. Vogt (2010), Magnetic polarity transitions knowledge from geology, astronomy, to our planet’s biota and biospheric effects, Space Sci. Rev., 155, 387–­ 410,​­ https://doi­ ​ .org/10.1007/­ s11214­ -​ 010­ -​ 9659­ -​ 6.­ is unclear given the plasma physics, microbiology, Lammer, H., et al. (2009), What makes a planet habitable?, Astron. complexity of Earth’s Astrophys. Rev., 17, 181–­ 249,​­ https://doi­ .org/​ 10.1007/­ s00159­ ​ evolutionary biology, and other biosphere and its -009­ -​ 0019­ -​ z.­ Lingam, M. (2019), Revisiting the biological ramifications of vari- disciplines. nonlinear interactions ations in Earth’s magnetic field, Astrophys. J. Lett., 874, L28, with the lithosphere, https://doi­ .org/​ 10­ .3847/​ 2041­ -​ 8213/­ ab12eb.­ hydrosphere, and atmo- Lingam, M., and A. Loeb (2017), Risks for life on habitable planets from superflares of their host stars, Astrophys. J., 848, 41, sphere. https://doi­ .org/​ 10­ .3847/​ 1538­ -​ 4357/­ aa8e96.­ Lingam, M., and A. Loeb (2019), Physical constraints for the evo- Resolving the Riddle lution of life on exoplanets, Rev. Mod. Phys., 91, 021002, https://­ doi.org/​ 10­ .1103/​ RevModPhys­ .91.021002.​ There is promising evidence that Earth’s Smirnov, A. V., et al. (2016), Palaeointensity, core thermal conduc- geodynamo initiated as early as 4.2 billion tivity and the unknown age of the inner core, Geophys. J. Int., years ago and that the crystallization of 205(2), 1,190–­ 1,195,​­ https://doi­ .org/​ 10.1093/­ gji/­ ggw080.­ Earth’s inner core, which paved the way for Tarduno, J. A., et al. (2020), Paleomagnetism indicates that pri- mary magnetite in zircon records a strong Hadean geodynamo, the geodynamo of today, occurred more Proc. Natl. Acad. Sci. U. S. A., 117(5), 2,309–­ 2,318,​­ https://doi­ ​ than half a billion years ago. Although the .org/10.1073/­ pnas­ .1916553117.​ changes in Earth’s magnetic field wrought by these transitions were likely profound, Author Information the concomitant effects on our planet’s bio- Manasvi Lingam (mlingam@fit​.edu), Florida sphere are much less clear. Earth’s organ- Institute of Technology, Melbourne isms must have been affected to some degree, but fathoming the magnitude and u Read the article at bit​.ly/­Eos​ nature of these repercussions necessitates -magnetic­ -​ shield­

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Congratulations to the 2020 Presidential Citation recipients: the teams from “Call for a Robust Anti-Racism Plan for the Geosciences” and “No Time for Silence”

The two teams, led by Dr. Ali and Dr. Morris, shared their framework recommendations for steps our community should take to make meaningful changes. Their teams’ words served as the framing documents for change from institutions small and large around the world including at AGU, where we committed to eight strong and meaningful actions to change and improve the scientific enterprise.

fromtheprow.agu.org/announcing-agu-2020-presidential-citation-recipients/

SCIENCE NEWS BY AGU // Eos.org 29 THE HERKY-JERKY WEIRDNESS OF EARTH’S FIELD Dented, erratic, and wandering, our fi eld is constantly changing its mind.

BY JENESSA DUNCOMBE

30 Eos // JANUARY 2021 NASA; JohanSwanepoel/Depositphotos.com SCIENCE NEWSBY AGU

// E os.org

31 ost people don’t know that Earth’s magnetic field has a magnetic field, satellites could be lost, and tools that rely weak spot the size of the continental United States hov- on careful magnetic models for navigation could go ering over South America and the southern Atlantic askew. Ocean. The answers can’t come soon enough. The magnetic We’re safe from any effects on the ground, but our field protects Earth’s atmosphere from harmful radia- satellites aren’t so lucky: When they zip through this tion emitted from the Sun. Scientists are learning that magnetic anomaly, they are bombarded with radiation the Sun is capable of emission events—solar flares— more intense than anywhere else in orbit. There is rea- even more destructive than we ever thought possible, son to believe that this dent in the magnetic field, and understanding our magnetic field strength and vari- called the South Atlantic Anomaly, is only getting big- ation is vital for knowing how at risk we could be from ger. the next big solar storm. This anomaly is far from the only unusual feature of Earth’s magnetic field. THE IRON HEART Hundreds of times in Earth’s history, our magnetic The puppeteer that drives the magnetic field is Earth’s field has reversed, switching north and south in a plane- core, the superheated heart of our planet, which burns as tary flip- flop. Earth’s magnetic North Pole keeps drift- hot as the surface of the Sun. ing too, stumbling around the Arctic in a chaotic dance. In the core, molten metals are constantly in motion as And scientists have detected pulses of Earth’s magnetic hot buoyant plumes of lighter material rise outward. At field—called geomagnetic jerks—that can undermine the very center lies a small hardened inner core that has our navigation systems. been growing as Earth cools. Yet forecasting these changes remains a challenge. This planetary anatomy sets the stage for an active “Just like weather forecasts, you can’t predict the evolu- magnetic field. The core’s constant need to cool itself, tion of the core beyond a few decades,” said Julien Aubert, and thus convect, drives our planet’s electric generator. a researcher at the Paris Institute of Earth Physics. The generator produces a self- sustaining magnetic field But scientists want to know how Earth’s magnetic field through a process called the geodynamo. The mathe- will change further into the future than that. Without a matics of the geodynamo are so messy that Albert Ein- stein did not believe the theory when one of its founders, Walter M. Elsasser, proposed it to him. The geodynamo works because the natural convection of the liquid core pushes metals through a weak existing magnetic field, exciting an electric current. Because of the relationship between electricity and magnetism, the current produces a second magnetic field, and the pro- cess repeats. This process has been self- sustaining for most of Earth’s history. Although the core sits thousands of kilometers beneath our feet, the magnetic field it produces stretches far into space, surrounding the planet like armor. But our planet’s armor isn’t perfect, and the results can be heartbreaking.

A CHINK IN EARTH’S ARMOR On an early spring day in 2016, teams of engineers in Japan watched as their prized satellite spun out of control. The teams behind Hitomi, a satellite launched just 5 weeks earlier, had hoped the spacecraft would observe black holes, galaxy clusters, and other high- energy fea- tures. The satellite even had a prized X- ray calorimeter, a triumph of 3 decades of engineering. But a cascade of events that began with encountering the South Atlantic Anomaly seemed to spell doom for Hitomi. Passing through the anomaly, the onboard sys- tem that controlled the satellite’s orientation glitched while it was pivoting to observe a new star cluster. The maneuver kicked off a series of software errors that left Hitomi spinning madly. Before long, the satellite broke into 11 pieces. The South Atlantic Anomaly currently covers parts of southern Africa, much of the southern Atlan- “It’s a scientific tragedy,” Richard Mushotzky, an tic Ocean, and South America. In 5 years, the region is forecast to grow and bifurcate. Credit: astronomer at the University of Maryland in College Weijia Kuang and Terence Sabaka/NASA GSFC Park, told Nature at the time.

32 Eos // JANUARY 2021 Other spacecraft have fallen prey to the South Atlantic Although the dent is projected to grow in the next Anomaly. The magnetic field intensity at the altitude of 5 years, it’s impossible to make predictions further into many satellites is half as strong in the anomaly compared the future, said Kuang. Fluid movement in Earth’s core is with elsewhere, and the weak field does not repel radia- so turbulent that a small perturbation to the system tion as effectively. The inner Van Allen radiation belt, a could lead to a cascade of out- doughnut- shaped disk of radiation around Earth that comes that we can’t foresee. traps high- energy particles, hugs much closer to the sur- The further you go in time, the face at the anomaly because of the weakened field. more runaway situations Any satellite in near- Earth orbit—a common altitude abound. Jerks may illuminate for Earth observing satellites—must travel through the Although the future is anomaly. The Hubble Space Telescope spends 15% of its uncertain, studying the anom- life in the region—and routinely shuts down its light- aly “provides a very good win- the core’s thermal sensitive cameras to avoid damage. Some instruments, dow for us to understand not like NASA’s Ionospheric Connection Explorer, power only the core dynamics,” said properties, a hotly down electrical components of an ultraviolet photon Kuang, but also “the regional detector every time they pass through. In the early days properties of this area.” debated topic that of the International Space Station, the anomaly would Luckily, the anomaly can’t crash astronauts’ computers. hurt life on the surface, said a ects our ideas But sometimes a satellite is just unlucky. Ashley Gree- Kuang. “But if it continues to ley, a postdoctoral scholar at NASA Goddard Space Flight weaken over time, this may Center, recalled a CubeSat that died shortly after launch. eventually impact us.” The about everything During start-up checks and the commissioning phase, hole in our field would expose “we think that an energetic particle hit it in the wrong us to high-energy particles that from the age of the place at the wrong time, and we never got data, unfortu- could surge power grids and eat nately,” she said. away at protective gases in our core to the onset of atmosphere. A GROWING ANOMALY plate tectonics. Researchers discovered the South Atlantic Anomaly in MAGNETIC SHUDDERS 1958 when satellites first began measuring radiation in AND A WANDERING POLE space. Now the region shows up prominently in most Chengli Huang’s daughter models, said NASA’s Terence Sabaka. “Everybody is would often hear a familiar pretty much in agreement on its size, shape, and story at bedtime. strength.” Although it’s still a matter of speculation, One day, four blind men decided to go to the zoo to there is some evidence that the anomaly has been visit an elephant. They’d never met one before, and they around since the very early 19th century and maybe even wanted to know what it looked like. The first man earlier. approached the elephant, felt its trunk, and declared it a The real debate surrounds what the anomaly will do “curved paddle.” The second touched its tail and con- next. cluded it was like a stick. The third man gingerly patted Greeley took her first look at the anomaly during her the body and pronounced that the animal looked like a doctoral work. Peering through 20 years of satellite data, wall, whereas the fourth felt its leg and said it was like a she calculated the extent of the anomaly during each pillar. pass of the Solar Anomalous and Magnetospheric Parti- Separately, the four men understood only one part of cle Explorer. Satellites in low Earth orbit pass through the elephant. But together, they had a clearer picture of the region every week or so, and the transit lasts for sev- the elephant’s true nature. eral minutes, she said. Huang tells this story to colleague Pengshuo Duan, Over time, Greeley found that the South Atlantic too. As astronomers peering into Earth’s interior, there Anomaly is moving westward (at about 1° longitude every is no way for them to “feel” the true nature of the core. 5 years) and ever so slightly northward. Eventually, “the But they can probe different aspects and collaborate bulk of it will be over land,” she said. The bull’s-eye of and compare with others to make a more complete pic- the anomaly will pass over Argentina, Bolivia, Brazil, ture. Chile, and Paraguay. Scientists have long been on this quest, sometimes A forecast from NASA scientist Weijia Kuang and Uni- with fatal consequences. Explorers of old perished trying versity of Maryland, Baltimore County professor Andrew to set up monitoring stations in far- flung locales, like Tangborn shows that in addition to migrating westward, the doomed English explorer Sir John Franklin, whose the anomaly is growing in size. Five years from now, the expedition to take magnetic observations of the North area below a field intensity of 24,000 nanoteslas (about Pole in 1845 ended with 129 men dead and two ships lost. half the normal magnetic strength) will grow by about As soon as long- lasting ground observatories sprung 10% compared with 2019 values. The dent may also be up around the world, scientists noticed strange devia- splitting, Kuang said, or perhaps another weak spot is tions in the field, including for example, that our mag- emerging independently and biting into it. netic North and South Poles roam freely around the

SCIENCE NEWS BY AGU // Eos.org 33 planet. It’s true that the poles sit off- kilter to Earth’s to avoid unacceptable naviga- rotational axes because of the uneven and turbulent flow tional errors. in the core, but they also drift gradually as the core’s Although the origin of jerks dynamics swirl field lines. Last century, the magnetic is a subject of active research, North Pole paraded through the Canadian Arctic, and a recent study in Nature Geosci- since the 2000s, it’s been sauntering across the Arctic ence by Aubert and Chris Finlay Ocean. at the Technical University of But occasionally, this gradual movement accelerates Denmark suggests that jerks seemingly at random, and the drift of Earth’s magnetic may originate from the push field skirts in another direc- and pull of forces in Earth’s tion. These diversions are interior (bit.ly/jerks - research). called geomagnetic jerks. When a hot plume shoots up Scientists also call the jerks through the outer core, the The dent may be “ V- shaped” events based on delicate balance between plan- their appearance in plots of the etary, rotational, and electro- splitting, or perhaps field’s rate of change over time. magnetic forces careens out of The events usually last between whack. The off- balance forces another weak spot is 1 and 3 years, and the first doc- send a shudder along magnetic umented case was recorded in field lines in the form of 1902. Dozens of jerks have waves. emerging and biting happened since. The next jerk may already be The last jerk was in 2016, under way. A recent analysis by into it. when it jostled the field and Huang and Duan predicted that dramatically shifted the North the next event would occur in Pole drift. The event was rather 2020 or 2021. inconvenient because scien- If that’s the case, scientists tists had just issued a 5- year model of Earth’s magnetic may need to update magnetic field called the World Magnetic Model (WMM). The maps on which industry and WMM team had to update the model ahead of schedule government activities rely. Companies drilling for oil and gas, for example, use fine- tuned magnetic models to dig boreholes. But not all jerks cause directional changes, so time will tell what the out- Earth’s magnetic field rate-of-change at come will be. Chambon-la-Forêt, France (nanotesla/year) 70 It’s too soon to know whether a jerk is happening right now, however. Finlay, part of a group that pub- lishes magnetic field models every 6 months, said it’s 1980 2011 impossible to identify geomagnetic jerks until well after 60 they’ve happened because researchers must look at the 1998 data over time. It would take about 2 years to know for 2003 sure, Finlay said. 50 Regardless of whether the next event is upon us, geo- magnetic jerks are one part of seeing the “elephant” of 2014 Earth’s magnetic field. Jerks may illuminate the core’s thermal properties, a hotly debated topic that affects our 40 2001 ideas about everything from the age of the core to the 2007 onset of plate tectonics. Solving the mystery of the jerk’s origin will remove a Eastward field component 30 1991 “stumbling block” of future magnetic field predictions, said Aubert, something we’ll sorely need to better understand our planet’s protective armor. 20 AVOIDING DOOMSDAY Vladimir Airapetian does not mince words when it comes 1969 to apocalyptic scenarios and our magnetic field. 10 1960 1980 2000 2020 In one grim scenario, a catastrophically massive solar year flare envelops Earth and knocks out the ozone layer, exposing us to damaging ultraviolet radiation known to You can spot jerks in the V- shaped graphs of the magnetic fi eld’s cause cancer. In the 6–12 months it would take to rebuild change in direction over time. Credit: Julien Aubert, IPGP/CNRS our ozone layer, we’d live like “nocturnal animals,” from French BCMT data Airapetian said.

34 Eos // JANUARY 2021 An artist’s rendering shows a solar fl are leaving the Sun and hurtling toward Earth. Credit: NASA

“You’d have to go underground and go out during the Sun. Recent research by Aira- nighttime,” said Airapetian, a NASA scientist at the petian suggests that gigantic The next jerk Goddard Space Flight Center. “That’s the Hollywood- solar flares are possible in our type scenario.” solar system. Observations of Tales of our field catastrophically failing are part of the other stars similar to the Sun may be already lore of working on Earth’s magnetic field. People always reveal that our Sun may be want to know, “When is the really, really bad stuff hap- capable of shooting out a flare under way. pening?” said Aubert. of epic proportions. Although the prevailing science suggests that these Congress passed PROSWIFT doomsday scenarios are possible, they are highly (Promoting Research and unlikely. Earth’s magnetic field is fickle, cratered, and Observations of Space Weather to Improve the Forecast- ever changing, but scientists have no reason to believe ing of Tomorrow Act) in 2020 to pour money into space that the field won’t protect us for decades—and most weather research, which the act’s authors called a mat- likely centuries—to come. ter of national security. Heliophysics is the smallest Even one of the most dramatic of the scenarios, a division at NASA, so Airapetian is “so excited” for the magnetic reversal, is implausible in the foreseeable additional funding and support to discover what space future. The last reversal occurred 780,000 years ago, and hazards lie ahead. over the multibillion- year lifetime of the magnetic field, Until then, our magnetic field will continue to do what researchers guess that the poles have switched hundreds it does best: drift, shiver, and morph into its next grand of times. configuration. But scientists have no compelling evidence to suggest that a field reversal is upon us, said Catherine Constable, AUTHOR INFORMATION a scientist at Scripps Institution of Oceanography who Jenessa Duncombe (@jrdscience), Staff Writer studies magnetic reversals. The field changes so gradu- ally that we’ll have fair warning, at least a few decades, ACKNOWLEDGMENTS Constable said. Eos thanks Weijia Kuang, who generously provided a Perhaps the more worrisome danger comes from forecast of the South Atlantic Anomaly upon request. space. The magnetic field is our main line of defense against the onslaughts of high- energy particles from the u Read the article at bit.ly/ Eos - magnetic - weirdness

SCIENCE NEWS BY AGU // Eos.org 35 Not all planets move the needle. But whatever planet you take a magnetic compass to, it’s sure to point out clues to secrets underfoot.

By Bas den Hond

ongratulations! With the IP9, the new interplanetary model in Eos’s signature line of magnetic compasses, you’ve chosen a travel companion that will serve you as best it can on the many ­GPS-​­challenged bodies of our solar system— be your plans a hike on Mercury, a ride on Mars, or a glide over Neptune. Before you start using your compass, please note that your warranty is voided when you drop your IP9 onto a hard surface or into a ­high-pressure​­ or C­high-temperature​­ environment, or store it unshielded from magnetic fields during extended periods of interplanetary travel. Other warnings and pointers, specific to select extraterrestrial destinations,

are as follows. Right: XXXX Top XXXXXX; This Page: Opposite Page:

36 Eos // JANUARY 2021 Good Studio/stock.adobe.com Opposite Page: XXXXXX; This Page: Top Right: XXXX SCIENCE NEWSBY AGU

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37 Bruce Buffett, of the Department of Earth and Planetary Science at the University of California, Berkeley, agreed. Models, he said, are characterized by how the friction forces associated with viscosity com- pete with the Coriolis forces associated with the rotation of the planet. “When we first started [modeling], the viscous forces were about 1,000 times less important than the Coriolis forces. In a realistic model, they are 1015 times less. In our current models, 105 or 106 is possible.” Achieving realistic conditions means that modelers like Buffett and Stanley need computers that are about 2,000 times faster than what they can currently get their hands on. If Moore’s law, which says computer power doubles roughly every 2 years, keeps working, scientists will get those computers in 11 years. In the meantime, researchers studying Mercury’s magnetic field have to work with approximations, which “do produce magnetic fields,” said Buffett. “There are some people who believe that if you go to lower viscosity, you stay in the same dynamical regime, and others say there could be something different, a change of phase almost. I’m not sure who’s right. But the results that we are getting now are useful.”

Destination: Mercury Destination: The Moon

On Mercury, using the compass will be straightforward. The structure of Although all major rocky bodies in our solar system have iron cores, your IP9 Mercury’s magnetic fi eld is much like Earth’s, so your compass will behave compass is unfortunately not suitable for use on Venus and the Moon and is approximately as if a huge bar magnet rests at the planets center, aligned of only limited use on Mars. with its rotational axis. Or—a bit closer to the mark—as if electric currents are girding that axis. The time when the Moon had a global magnetic field is long past. Your compass will at most pick up remanent magnetization in some Do give your needle time to adjust. Mercury’s magnetic field, which lunar rocks. was measured by the MESSENGER (Mercury Surface, Space Environ- ment, Geochemistry and Ranging) spacecraft that orbited the planet from 2011 to 2015, is only 1.1% the strength of Earth’s. And pay attention to space weather: “Because Mercury is much closer to the Sun,” said Sabine Stanley, a professor in the Department of Earth and Planetary Sciences at Johns Hopkins University, “and because the planet’s magnetic field is much weaker than Earth’s field, there are times when the solar magnetic field gets really important, even very close to the planet. Your compass may actually measure fields in the magnetosphere of Mercury that are caused by interaction with the solar wind. We call them external magnetic fields because they are due to currents flowing outside of the planet, not inside of it.” In rocky planets like Mercury and Earth, any such internal electric currents flow in the iron cores they obtained when they were young and hot, and their materials separated out according to density. “The biggest thing Mercury’s field tells you is it has an iron core, and that core is still partly liquid and moving around,” said Stanley. “Before we can really understand what the field tells us about the planet, we need to understand what the composition is of the core, Rocks like the Contingency Sample, above, the very fi rst sample picked up from what’s mixed in with the iron, what are the temperatures. We learn a the Moon, provide clues to the Moon’s magnetic past. Credit: NASA/Astro- little bit about that from the composition of the surface.” materials 3D Those assumptions about composition eventually go into model- ing, which is what Stanley does. The goal is to predict how an iron core, wholly or partially fluid, sheds its primordial heat. If this hap- pens fast enough, convection will occur. As swirls of electrically con- That the field is absent tells us that the lunar core is fairly quies- ducting fluid both create and are moved around by magnetic fields, cent, said Sonia Tikoo, an assistant professor of geophysics at Stan- they become a self- sustaining source of such fields: a dynamo. But ford University. modeling that process realistically is not really possible just yet, said The ages of magnetized rocks constrain the time when a dynamo Stanley. “Because the viscosity of the iron is so low, the flows are tur- was active inside the Moon. But there are large uncertainties to those bulent at a small scale, so in our simulation we would really need high constraints, due to the limited samples of rocks that Apollo astro- resolution, a lot of grid points.” nauts brought back to Earth.

38 Eos // JANUARY 2021 “At least prior to 3.5 billion years ago, the field appears to have power available to generate those motions you need in the cores of been as strong as Earth’s,” Tikoo said. “After that it was an order of these planetesimals.” magnitude weaker. It lasted at least until 1.9 billion years ago, and That power would have come from a radiogenic isotope of alumi- very likely was turned off by 0.9 billion years ago.” num, Al-­ ​­26. “It has a very short ­half-​­life,” said Stanley, “so all of it These numbers pose hard questions for modelers. The early mag- has already decayed today, but very early in the solar system it was an netic field seems too strong to have been generated by the sort of available heat source.” dynamo the Moon’s heat budget could sustain. “So people are looking The decay of ­Al-​­26, according to Stanley’s calculations, could com- at alternatives that are mechanical in nature,” Tikoo said. pletely melt a planetesimal, allowing an iron core first to form in its One possible energy source is precession, with the core and man- center and then to cool down through convection, creating a ­short-​ tle, and perhaps a liquid outer core and a solid inner core, rotating ­lived dynamo. around different axes. “That can generate turbulence in the fluid core Many planetesimals are still around, for instance, as Kuiper belt and power a dynamo,” said Tikoo. “But what is missing is any mag- objects, and two have been visited by a spacecraft: the contact binary netohydrodynamic simulation. Nothing yet has been published that Arrokoth and the dwarf planet Pluto. When New Horizons came call- says, ‘Yes, you can do this.’” ing, however, it didn’t bring a magnetometer. Its designers didn’t think such an instrument would measure anything while passing Destination: Venus Pluto. Pluto’s small size and slow rotation—its day takes almost an Earth week—work against any dynamo activity. Stanley is quite sure: For Venus, information about any past magnetic field is even scarcer. “Pluto does not have a magnetic field.” “We don’t know what we would see your compass do,” admitted Joe Whether Venus ever had a dynamo can be established only by a O’Rourke, an assistant professor in the School of Earth and Space new ­magnetometer-​­equipped mission. Exploration at Arizona State University. “One possibility is that it O’Rourke hopes the recent discovery of phosphine in the Venusian would do nothing, because there never was a magnetic field of any atmosphere will be an impetus to go there again. “Just the fact that kind. The second is that it would occasionally behave erratically as we don’t understand fundamental things about Earth’s nearest you encounter regions of the crust that are magnetized.” neighbor is humiliating to our attempts to claim that we Such regions would prove that Venus did have a magnetic field and understand anything about planetary evolution. that it was preserved in rocks. But whether those rocks exist is any- one’s guess. “The mission that provided the tightest constraints on the magnetism of Venus was the Pioneer Venus Orbiter, which launched in the late ’70s,” said O’Rourke. “All we really know is that if there is a magnetic field at Venus, it has to be 100,000 times weaker than Earth’s magnetic field.” “IF THERE IS A MAGNETIC The most likely explanation for the absence of a magnetic field FIELD AT VENUS, IT HAS TO BE now, according to O’Rourke, is that the Venusian lithosphere is not broken up into wandering continental plates. “Because there is no 100,000 TIMES WEAKER THAN plate tectonics, [Venus’s] silicate mantle probably cools down slowly, EARTH’S MAGNETIC FIELD.” and the mantle is what is insulating the core. So Venus could have a core that is exactly the same size, exactly the same composition, as Earth, but cooling down more slowly over time.” Venus could also differ from Earth in radical ways that would reduce the strength of its magnetic field or prevent it from having one at all. A chemical gradient in the core, for instance, or an insulat- ing ocean of molten rock surrounding the core may prevent convec- tion in the planet’s interior. If Venus never had a magnetic field at all, it would be a very special planet indeed. Research on the remanent magnetism of meteorites suggests that even some planetesimals, the building blocks of planets like Earth and Venus, had iron cores that for a time produced dyna- mos. Stanley has studied a class of very old meteorites called angrites. “They’re dated very close to the beginning of the solar system,” she said, “and they have a magnetic signature in them that seems to sug- gest they formed on a body that had a dynamo. Nothing else, like solar wind or flares, is strong enough [to form the magnetic signa- ture]. And the field has to be very stable, for about tens of thousands of years, because rocks cool very slowly, and they imprint an average field over that time.” “So we did some modeling to ask the question, Could a planetesi- mal, something that’s maybe 100 kilometers to a few hundred kilo- The VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectros- meters in radius, generate a dynamo?” Stanley continued. “And we copy) orbiter, seen here in an artist’s rendering, is one of many proposed missions found that yes, in certain circumstances you could have enough to Venus.

SCIENCE NEWS BY AGU // Eos.org 39 THE NEXT MARS MISSION WILL ARRIVE IN FEBRUARY WITH A There have been ROVER, PERSEVERANCE, BUT many great mission proposals for Venus WITHOUT A MAGNETOMETER. that are technically ready, they’re scientifi- And then because cally valuable. NASA just Mars is smaller, the field at has to pick one.” the surface is closer to the core.” In the early days of the space It would be possible to study the core by program, O’Rourke said, “Venus observing seismic waves traversing the planet and Mars shared the glory. The first from several locations simultaneously. But there is successful interplanetary flyby mission only one working seismometer on the planet, brought went to Venus.... The Soviet Union sent land- there on the 2018 Mars InSight Mission. ers to Venus. But in recent decades, Venus has abso- The InSight lander also had a magnetometer on board. “And from lutely been neglected and Mars stole the show.” that single data point, where that probe landed, we were able to vali- date a lot of the global mapping from orbit,” Buz said. “When it Destination: Mars landed, [we found that] the field was a lot stronger than we had mod- eled.” We have a clearer picture of Mars’s magnetic properties because it But here, too, data from one instrument at one location are limit- has been the subject of so many recent missions. ing. “It would be really great if we could have a magnetometer on According to Jennifer Buz, a postdoctoral scholar in the Depart- one of the rovers,” said Buz. “To see the minute changes in the ment of Astronomy and Planetary Science at Northern Arizona Uni- magnetization as the magnetometer traverses the planet would versity, travelers to Mars may want to avoid the northern hemisphere shed a lot of light on why [Mars has] such variable crustal magneti- if they are going to rely on a compass. “Most of the north is unmag- zation.” netized, [so] it wouldn’t do much,” she said. “But as you go south, NASA’s next Mars mission will arrive in February with a rover, there is a region where the crust is really strongly magnetized, in Perseverance, but without a magnetometer. But it looks like Buz’s alternating fashion. Some people think it’s like the magnetic seafloor wish will be fulfilled by a Chinese mission that launched in the stripes that we have on Earth. If you were to traverse significant same month, July 2020. ­Tianwen-​­1 (the name means “Heavenly lengths of the southern hemisphere [on Mars], the compass would Questions”) will also arrive in February, and put a rover down in completely switch direction multiple times.” May. This rover carries the Mars Surface Magnetic Field Detector, These anomalies indicate that Mars once had a core dynamo and which will measure the field to an accuracy of better than 0.01 nan- suggest that its magnetic field was strong for its size, about as otesla. That’s less than a millionth of the field strength of Earth. strong as Earth’s. “But there are ways to explain that,” said Buz. “Historically, it’s been hard to access data from Chinese missions,” “Mars has a lot more iron, so it could have a more significant core. Buz said, “but it looks like this mission has a lot of international collaboration. I’m excited for their results.”

Destination: Gas Giants

If you’re the kind of traveler who is slightly annoyed that your magnetic compass doesn’t quite point to the geographic North Pole on Earth, then Saturn is your magnetic ­Shangri-​­la, while you may give Jupiter a pass.

“Saturn’s field is unique: It’s almost perfectly axisymmet- ric,” said Stanley. But on the other gas giant of the solar sys- tem, the compass is tricked by flux patches not far from the poles, where additional field lines emerge. The flows of conducting material that a dynamo needs are not located in the metal cores of gas giants—if the The next Mars mission will arrive in February with a rover, Perseverance, but without a magnetometer. Credit: NASA/JPL-­ ​­Caltech planets even have them.

40 Eos // JANUARY 2021 Instead, scien- Destination: Ice Giants tists think the flows arise at Great caution is advised when magnetically navigating Uranus and Nep- higher levels, where tune. The magnetic fields of the solar system’s two ice giants are not dipolar the hydrogen that makes but multipolar, said Stanley. “They have lots of places where field lines come up the bulk of these planets out of the planet and go into the planet. So you never know where your is hot and pressurized enough to compass is going to be pointing.” become metallic. Modelers can produce a field like Jupiter’s, The poles of our solar system’s ice giants may not even be fixed. but as for Saturn, “it’s really hard to generate a dynamo that pro- “The only data we have [are] from a single flyby of both planets by duces a symmetric field,” said Stanley. “You have to do something the Voyager II spacecraft in the late ’80s,” said Stanley. “So all we special in the interior.” have is a snapshot in time of the field. We think they move around. This would perhaps be some kind of shielding layer around the But we don’t know at what speed.” dynamo. “As you go deeper into Saturn and the hydrogen becomes Uranus and Neptune consist of water, ammonia, and methane metallic...the helium that is mixed in with the hydrogen doesn’t ices, which may contribute to the planets’ magnetic potential. transition [to metal], and it can actually rain out of the hydrogen.” “When you’re The result is a ­helium-​­depleted layer covering the dynamo region. “It thinking about could act as a shield that gets rid of any of the nonaxisymmetric fields dynamos and that we otherwise might see at the surface.” magnetic field generation,” said Destination: Galilean Moons Stanley, “you have to ask: Where in While you’re in the neighborhood of the gas giants, it seems a shame not to the planet can I have a quick visit to some of the Galilean satellites. “They’re really interest- get a material that ing,” said O’Rourke. is going to be fluid, and a good Of Jupiter’s Galilean moons—Io, Europa, Ganymede, and Cal- electrical conduc- listo—the first three are thought to have iron cores, based on their tor? For Uranus gravitational pull on the Galileo spacecraft that cruised around the and Neptune, as Jovian system from 1995 to 2003. Only one of them, though, Gany- you descend into Saturn’s magnetic field lines (red) are symmetric, mede, has a core with an active dynamo, producing a strong dipole the planet, and the planet’s dipole axis (M) and its rotation field. water—as you axis (Ω) are nearly perfectly aligned. Credit: NASA/­ Why the others don’t is a puzzle O’Rourke is working on. “It could keep putting it JPL-​­CaltechDQ: Your compass may actually mea- be related to the amount of tidal heating in these worlds. Io, of under higher and sure fields in the magnetosphere of Mercury that are course, is super close to Jupiter—it is being violently heated by tides, higher pressure— caused by interaction with the solar wind. and if the rocky part of Io is superhot, maybe even liquid, that would becomes ionic. insulate the metal core. Whether or not that process also works on The bonds in the Europa is totally unclear.” molecules break, Not having a dynamo doesn’t mean a Galilean moon can’t be an and you have ­OH-s​­ and H+s ions of water. And those can carry electric interesting place to bring a compass. Near Europa and Callisto, for charges, creating a current. So we think the dynamos in Uranus and example, Galileo measured perturbations of the magnetic field of Neptune happen in the ionic water layers. We don’t know how deep Jupiter. Instead of dynamos, these moons are thought to be the the dynamo region goes, and we really don’t understand what hap- solar system’s induction coils. Stimulated by changes they experi- pens to the water.” ence in the magnetic field of Jupiter as it rotates, electric currents flow inside the moons, and these in turn bring about magnetic fields Some Final Pointers that counteract the changes. The existence of the fields is taken as evidence that hidden under the surfaces of Europa and Callisto are Clearly, tourist excursions in the solar system are not for the fainthearted— salty oceans. Compass readings on these moons will be hard to and at present, travel insurance is available only for the rocky planets, with interpret without detailed knowledge of where the satellite is in its deductibles varying from very reasonable (the Moon) to quite steep orbit. (Venus). This may well change as further data become available and mag- netohydrodynamic models improve. Those who have an itch to go farther afield should follow the Earth science journals for the latest developments and, of course, Eos, proudly your companion in all your interplanetary adventures.

Author Information INSTEAD OF DYNAMOS, THESE MOONS ARE THOUGHT TO BE THE Bas den Hond ([email protected]),​ Science Writer SOLAR SYSTEM’S INDUCTION COILS. u Read the article at bit.ly/Eos-field-guide

SCIENCE NEWS BY AGU // Eos.org 41 RESEARCH SPOTLIGHT

A Juno Era Model of the Jovian Magnetosphere

upiter creates the solar system’s most powerful planetary magnetic field, and Junderstanding its region of influence, called the magnetosphere, is vital to nearly all observations of the Jovian system. The first estimates of Jupiter’s magnetosphere were developed in anticipation of the first space- craft flybys in the 1970s. The 1979 visits by the dual Voyager spacecraft provided data suffi- cient to construct a robust empirical model of the magnetosphere within 30 Jovian radii (RJ) of the planet. The Voyager model, which represents Jupi- ter’s magnetospheric configuration with a disklike geometry, remains in use today. However, the arrival of NASA’s Juno space- craft in 2016, which provided highly detailed measurements of Jupiter’s plasma environ- ment, revealed discrepancies in that model. Connerney et al. extend the Voyager model and refit it to Juno observations to improve mis- sion planning and data interpretation. The result is a model that empirically describes the magnetosphere without attempting to explain the physical processes that produce it. The authors fit the Voyager model with all ­high-resolution​­ Juno magnetic field data col- This view of Jupiter was captured by the Juno spacecraft on 17 February 2020.Credit: Image data: NASA/JPL-­ ​ lected within 30 RJ on Juno’s first 24 polar ­Caltech/SwRI/MSSS; image processing: Kevin M. Gill orbits. That model relies on an axisymmetric current sheet that encircles Jupiter, with azi- muthal currents confined to a washer-­ shaped​­ region near the magnetic equator. The researchers augmented this system of azi- muthal currents with another system of radial currents that flow outward from the inner edge of the disk. The resulting best fit model describes the magnetosphere as a slightly inclined disk with a total thickness of 7.2 RJ, an inner radius of 7.8 RJ, and an outer radius of 51.4 RJ. This Juno-­ ​­based model was evaluated through observations of charged particle interactions with Jupiter’s large moons and was found to substantially outperform the Voyager era one. The authors also examined ­orbit-​­to-​­orbit variations in the modeled current sheets; the azimuthal current appears to remain steady, whereas the radial current shows larger change. This variation may indicate activity in the mag- netosphere, the researchers noted, and may be useful in interpreting Jupiter’s aurorae. ( Journal of Geophysical Research: Space Physics, https://doi­ ​.org/10.1029/­ ­ 2020JA028138, 2020) —Morgan Rehnberg,​ Illustration of Jupiter’s complex magnetosphere, including the current sheet. Science Writer Credit: Fran Bagenal and Steve Bartlett

42 Eos // JANUARY 2021 RESEARCH SPOTLIGHT

How Long Does Iron Linger in the Ocean’s Upper Layers?

ron is in our blood, our buildings, and our the new research narrows the window, find- biomes. In our oceans, iron helps regulate ing that in most cases, the residence time for Iglobal climate by sustaining carbon-­ ​ total iron is between 10 and 100 days. Subant- ­catching phytoplankton. However, current arctic regions are an exception. As there is environmental models have difficulty pin- very little iron in these areas, residence times ning down the relationship between climate depend on local events like infusions of iron and marine iron cycling because they have from atmospheric dust or from eddies and few data to go on. vary from just a day up to decades. In new research, Black et al. conducted an The researchers also found that dissolved extensive observational study as part of the iron has inconsistent residence times that vary international GEOTRACES program to inves- in monthlong to yearlong cycles depending on tigate iron residence times in the top 250 local conditions. Organisms may respond to meters of the ocean and to close gaps in pre- Subantarctic waters along the West Antarctic Penin- seasonal or other changes in their environ- vious results. sula are seen from the R/V Palmer in 2009. Credit: ment to take up more or less dissolved iron. Iron in the ocean comes in various forms, Ken Buesseler All told, the residence times of iron indi- depending on its bonding with other materi- cated in the new study are shorter than pre- als. Particulate iron may coat dust grains sus- vious studies have estimated. The researchers pended in the water column, for example, and suggest that the new data and results should is largely inaccessible to marine life because other forms of iron behave differently in help to develop improved biogeochemical it typically sinks out of the upper ocean before marine environments, their residence times models that better predict carbon sequestra- it dissolves and becomes available for organ- will differ. tion in the ocean. (Global Biogeochemical isms. Dissolved molecular iron, meanwhile, Whereas previous studies have estimated Cycles, https://­doi.org/​ ­10.1029/­2020GB006592, is more bioaccessible. Because these and residence times ranging from days to years, 2020) —Elizabeth Thompson, Science Writer

Capturing ­Heat-​­Driven Atmospheric Tides on Mars

n Mars, heat from the Sun drives daily ing tidal pulses that repeat daily or twice changes in temperature, wind, and daily. Some of these tidal patterns match the Opressure in the atmosphere. Known path of sunlight as it sweeps across the as atmospheric tides, these regular patterns planet, others are out of sync with the Sun but play a major role in shaping the planet’s still follow a regular schedule. weather. The MCS observations aligned well with Atmospheric tides exist on Earth as well, predictions of tidal patterns from the Labo- but they have a much greater influence in ratoire de Météorologie Dynamique’s Global Mars’s thin atmosphere. The details and driv- Climate Model, as captured in the Mars Cli- ers of atmospheric tides on Mars have mate Database. The model predictions also remained unclear, however. Now Forbes et al. showed how these ­middle-​­atmosphere tidal present new spacecraft data and model sim- patterns could give rise to longitudinal vari- ulations that deepen our understanding of ations in density that have been observed in tidal patterns in the middle and upper atmo- the upper atmosphere by the Mars Global sphere of Mars. Surveyor. The new observations came from NASA’s In addition, the researchers used the model The thin atmosphere of Mars, visible on the horizon Mars Climate Sounder (MCS), an instrument predictions to explore how certain atmo- in this image taken by the Viking 1 spacecraft, mounted on the Mars Reconnaissance spheric processes could drive tidal patterns undergoes daily variations in temperature, wind, and Orbiter, which has circled the Red Planet that result in variations in atmospheric den- pressure driven by solar heating. Credit: NASA since 2006. The researchers analyzed about sity at different altitudes and latitudes, and at 9 years of ­MCS-captured​­ temperature data for different times of the year. the middle atmosphere, revealing how tidal The findings support the use of the Mars patterns shift as the ­north-​­south angle at Climate Database to study atmospheric tides and that future work may examine discrep- which Mars faces the Sun changes over the and could boost scientists’ ability to predict ancies between predictions and observations. course of each year. the planet’s weather. The researchers say ( Journal of Geophysical Research: Space Physics, Key patterns emerged from the MCS data, they plan next to compare model predictions https://­doi.org/​ ­10.1029/­2020JA028140, 2020) including eastward and westward propagat- with observations from additional spacecraft —Sarah Stanley, Science Writer

SCIENCE NEWS BY AGU // Eos.org 43 EDITORS' HIGHLIGHTS // AGU ADVANCES EDITORS PRESENT THE LATEST RESEARCH

Ensemble Modeling of Coronal Mass Ejection Arrival at 1 Astronomical Unit

he Solar Stormwatch project coordinates citizen scientists in arrival time of the CME perturbation of the solar wind at Earth. tracking coronal mass ejection (CME) events observed in white Ensemble modeling of different determinations of the inner boundary Tlight from the Solar Terrestrial Relations Observatory (STE- condition improves the forecast arrival time of CME disturbances of REO) A and B spacecraft at different heliographic longitudes orbiting the solar wind at Earth, an important driver of space weather. Radia- at 1 astronomical unit. The HI1 instruments, identical on both space- tion threats to spacecraft and astronauts, as well as ground-induced craft, are white-­ ​­light imagers that observe sunlight that has been currents that can shut down power grids, are examples of space Thomson scattered by solar wind electrons. Barnard et al. use the HUXt weather effects produced by strong CMEs. Advanced warning of arrival numerical model, which uses these STEREO white-light images as time may allow mitigation. (https://doi­ .org/​ 10.1029/­ 2020AV000214,­ input, treats the solar wind as a 1D incompressible­ fluid and solves for 2020) —Mary Hudson

More Clustered Clouds Amplify Tropical Rainfall Extremes

(a) Observed time series of sea surface temperature (SST) anomalies (red; in Kelvins) and percentage anomalies of degree of convective aggregation (black; in %) in the trop- ics between 30°S and 30°N. (b) Monthly percentage anomalies of instantaneous precipitation frequency in 13 bins. Higher frequency of extreme precipitation corresponds to warmer SST anomalies and the higher degree of large-­ ​­scale aggregation. Credit: Dai and Soden, 2020

recipitation extremes, already shown to be increasing, have However, within the tropics, the rate of intensification of extreme substantial implications for both human and natural systems. precipitation with warming is implied by the thermodynamic argu- P Extreme precipitation is expected to increase further with ment, hinting at an unknown contribution from atmospheric dynam- warming from a simple thermodynamic relation that implies an ics. Dai and Soden reveal that the degree of cloud clustering (i.e., con- exponential increase in atmospheric moisture with temperature. vective aggregation) amplifies the response of tropical precipitation extremes to surface warming on a ­year-to-​­ year​­ basis in both satellite observations and climate model simulations. More specifically, pre- cipitation extremes and convective aggregation increase during El u Sign up for the AGU Advances Digest: Niño events compared with La Niña events. The newly revealed link- agu.org/avances-digest age between convective aggregation and precipitation extremes offers insights into their potential response to future warming. (https://doi­ ​ .org/10.1029/­ 2020AV000201,­ 2020) —Sarah Kang

44 Eos // JANUARY 2021 POSITIONS AVAILABLE

In collaboration with NOAA’s Geo- prior to application to discuss areas of physical Fluid Dynamics Laboratory possible research. (GFDL), the Atmospheric and Oce- Complete applications, including The Career Center (findajob.agu.org) anic Sciences Program at Princeton a CV, copies of recent publications, University solicits applications to three letters of recommendation, and its Postdoctoral Research Scientist a research proposal of approximately is AGU’s main resource for Program funded by the Cooperative 5 pages including the project title, Institute for Modeling the Earth should be submitted by December recruitment advertising. System (CIMES). 8th, 2020 for full consideration. A The AOS Program and GFDL offer goal of our department is diversifying a stimulating and supportive envi- the community of scientists and AGU offers online and printed ronment with significant computa- making the field more equitable and tional and intellectual resources in inclusive. With this in mind, we will recruitment advertising in Eos to which to conduct collaborative or take into consideration personal independent research for the model- experiences as well as efforts in edu- ing, understanding and predictability cation, outreach or other service reinforce your online job visibility of the Earth System from weather to activities related to Earth system sci- centennial time scales. We primarily ence or other sciences, which may be and your brand. Visit employers seek applications from recent Ph.D.s described in a separate section of the for postdoctoral positions but will research statement. Applicants must .agu.org for more information. accept applications from more expe- apply online to https://­www​ rienced researchers. Appointments .princeton­ ​.edu/­ ​­acad-​­positions/​ are made at the rank of Postdoctoral ­position/­18341. We would like to Research Associate, or more senior, broaden participation in earth system initially for one year with the possi- scientific research and therefore Eos is published monthly. bility of renewal for a second year encourage applications from groups based on satisfactory performance historically ­under-​­represented in and continued funding. A competitive science. These positions are subject Deadlines for ads in each issue are published at eos.org/advertise. salary is offered commensurate with to the University’s background check experience and qualifications. policy. We seek applications in all areas of Princeton University is an equal Eos accepts employment and open position advertisements from earth system science within the three opportunity employer and all qualified governments, individuals, organizations, and academic institutions. research themes of CIMES: 1) Earth applicants will receive consideration We reserve the right to accept or reject ads at our discretion. System Modeling; 2) Seamless pre- for employment without regard to age, diction across time and space scales; race, color, religion, sex, sexual orien- 3) Earth System Science: Analysis and tation, gender identity or expression, Eos is not responsible for typographical errors. Applications. The broad scope is national origin, disability status, pro- improved representation of processes tected veteran status, or any other in models, ­high-resolution​­ modeling, characteristic protected by law. and advancing the understanding of the Earth System including its varia- The laboratory of Professor ­Ching-​ tions, changes, feedbacks, and sensi- ­Yao Lai in the program of Atmo- Atmospheric Sciences dates, including letters of recommen- tivity utilizing models and observa- spheric and Oceanic Sciences (AOS) dation, will only be made available for tions. Current areas of particular interest and Geoscience (GEO) at Princeton COLORADO STATE UNIVERSITY review by the broader faculty of the are: Stratosphere-­ ​­troposphere University invites applications in ATMOSPHERIC SCIENCE TENURE Department of Atmospheric Science ­radiative-chemical-​­ dynamical​­ inter- the broad areas of fluid dynamics TRACK FACULTY POSITION AND if the applicant reaches the semifi- actions, and predictability; ­Aerosol-​ and geophysics for a postdoctoral DIRECTOR OF THE COOPERATIVE nalist stage. Full details of the posi- ­cloud-​­precipitation-​­radiation inter- position starting March 2021 or INSTITUTE FOR RESEARCH IN THE tion can be found at the link below. actions including ice and ­mixed-phase​­ later. A Ph.D. in physical sciences, ATMOSPHERE Applicants should submit a cover let- microphysics, and effects on weather engineering, applied mathematics, Colorado State University invites ter, one to two page statements on and climate; Lower ­atmosphere-​ or a related field is required prior to applications for a tenure track faculty their vision for CIRA leadership ­surface interactions over land and starting. We are looking for candi- position in the Department of Atmo- (uploaded to the special required doc- ocean; Land surface processes and dates with a keen interest in fluid spheric Science. This hire will also umentation slot) and on research and atmospheric precursors of risks; dynamics, nonlinear dynamics, serve as Director of the Cooperative teaching interests, a statement on Ocean dynamics and its role in cli- interfacial phenomena, ice dynamics, Institute for Research in the Atmo- your commitment to diversity and mate, and impacts on coastal regions climate science, or fluid-­ ​­structure sphere (CIRA). The faculty appoint- inclusion (uploaded to the other slot), and marine resources; Subseasonal to interactions. Research experience in ment will be made at the rank of a curriculum vitae, and the names of seasonal predictions of ­high-​­impact mathematical modeling, numerical Associate Professor or Professor. We four references (who will not be con- weather events; Decadal projections methods or machine learning is pre- solicit candidates in CIRA’s core focus tacted without prior notification of of regional climate and extremes ferred. Our group aims to combine area of merging satellite observations the candidate) at the following link: using large high-­ ​­resolution climate mathematical models (analytical or and models. This is interpreted as http://­jobs​.colostate​.edu/­postings/­ model ensembles; Detection and computational) and ­machine-​ expertise in Satellite Remote Sensing, 81206. Applications must be submit- causal attribution of climate change; ­learning algorithms­ to address the Regional and Global Model Develop- ted online. Applications of novel machine learn- environmental and climate chal- ment, or Data Assimilation, with Please address inquiries about the ing methods; Downscaling tech- lenges facing society, such as pre- emphasis on individuals working at position to: niques to address regional climate dicting the future of ice dynamics in the interfaces of these areas. Professor Peter Jan van Leeuwen, and weather impacts. a warming climate and improving its Applications and nominations will Search Committee Chair Further information about the AOS physical representation in climate be considered until the positions are Department of Atmospheric​ Program may be obtained from: models. Appointments are for one filled; however, applications should Science http://aos­ ​.princeton​.edu, and about year, renewable annually based on be received by January 20, 2021 to Colorado State University GFDL from http://­www​.gfdl​.noaa​ satisfactory performance and avail- ensure full consideration. The search Fort Collins, CO .gov. Applicants are strongly encour- able funding. See our group website will remain open until the position is ­80523-​­1371 aged to contact potential hosts at for more info about our research: filled. Application materials of candi- [email protected]​ GFDL and/or Princeton University ­cylai​.­princeton​.­edu

SCIENCE NEWS BY AGU // Eos.org 45 POSITIONS AVAILABLE

The Princeton AOS program race, color, religion, sex, sexual ori- clouds/aerosols, radiation, circula- mary focus on designing a new ­line-​ emphasizes theoretical studies and entation, gender identity or expres- tion, precipitation and extreme ­by-line​­ atmospheric radiative trans- numerical model studies of the global sion, national origin, disability status, weather/climate events. This search fer code that will serve as a climate system, and applicants are protected veteran status, or any other represents a concerted effort to push benchmark standard for weather/cli- expected to have a strong background characteristic protected by law. this prominent ­research direction to mate models. The position will also in natural sciences and mathematics. new levels. involve improving the model repre- The AOS program benefits from the The Atmospheric and Oceanic Sci- The first position will be in the sentation of cloud ­microphysics-​ research capabilities of the Geophys- ences Program at Princeton Uni- area of ­aerosol-​­cloud interactions ­radiation interactions based upon ical Fluid Dynamics Laboratory versity, in association with NOAA’s and indirect effects, with focus on results from the aforementioned (GFDL) of the National Oceanic and Geophysical Fluid Dynamics Labo- understanding the controlling factors radiation code. Atmospheric Administration. Many ratory (GFDL), seeks to fill up to of the magnitude and spatiotemporal The ideal candidates have to GFDL climate modelers are active in three postdoctoral or more senior distribution of ­model-​­simulated demonstrate a strong background in the AOS program as lecturers and research positions in a research aerosol indirect effects, using satel- atmospheric and climate modeling, broadly collaborate with AOS stu- initiative aiming at advancing the lite/­in-​­situ observations to validate and climate science, as well as expe- dents and postdocs. fundamental understanding of the the model representation of aerosol/ rience in using, developing, and ana- Applicants must apply online roles of clouds and radiation in cloud processes, and developing/ lyzing numerical models and/or large https://​­www​.­princeton​.­edu/​­acad​ affecting Earth’s climate and implementing parameterizations of observational datasets. -­positions/​­position/​­18221 by Febru- weather, and evaluating/improving ice nucleation and mixed-­ phase​­ cloud Candidates must have a Ph.D. in ary 1, 2021, 11:59 EST. Submit a cover their representation in GFDL cli- microphysics. atmospheric physics, dynamic mete- letter, CV, one or more ­first-​­author mate/weather models. The recently The second position will be in the orology, Earth system science, cli- publications, contact information for developed GFDL climate models (CM4 area of cloud feedbacks, with focus on mate studies, or related fields. The at least three references, and a ­1-​­2 and ESM4) are among the ­best-​ understanding the key processes in initial appointment is for one year page research statement including ­performing CMIP6 models in terms affecting the cloud feedbacks and cli- with the possibility of renewal subject previous research accomplishments of mean climate and variability. They mate sensitivity in coupled ­ocean-​ to satisfactory performance and and current interests. use the same FV3 dynamical core as ­atmospheric models. This includes an available funding. This position is subject to Prince­ the current NOAA/NWS weather investigation of effects of SST warm- Complete applications, including ton University’s background check forecast model. CM4 also forms the ing patterns on cloud feedback a cover letter, CV, publication list, a policy. basis of a prediction model (SPEAR) strength and coupled model simula- statement of research interests, and Princeton University is an equal and can be configured into a ­limited-​ tion of historical and future warming contact information of 3 references opportunity/affirmative action ­domain ­cloud-resolving​­ model (CRM) trends. should be submitted by December employer and all qualified applicants for process-­ ​­level studies. GFDL has The third position will be in the 1, 2020 for full consideration. Appli- will receive consideration for a long tradition in conducting area of atmospheric radiative transfer cants should apply online to https://­ employment without regard to age, ­cutting-​­edge research related to and cloud radiative effects, with pri- www​.princeton​.­edu/​­acad​-­positions/​

46 Eos // JANUARY 2021 POSITIONS AVAILABLE

­position/16001.​­ For more information radiocarbon AMS dating facility in CAIS operates with fiscal and scien- comes expertise in either experimen- about the research project and appli- the U.S. and is accredited under ISO/ tific integrity and will be responsible tal (satellite, airborne, or ­ground-​ cation process, please contact IEC 17025:2017. CAIS contains ­state-​ for ensuring that it supports inter- ­based instrumentation) or modeling V. Ramaswamy­ (V. Ramaswamy@ of-­ the-​­ art​­ facilities for radiocarbon disciplinary work at UGA and offers (numerical weather prediction, cli- noaa​.gov) for general inquiries, Yi dating, environmental analyses, food training opportunities for under- mate modeling, machine learning, Ming (Yi.Ming@noaa​.gov) for the flavor and beverage authenticity graduate and graduate students. CAIS big data applications) areas. first position, Ming Zhao (Ming​ testing, and bio-­ based​­ product test- collaborates with UGA’s Departments 2) Space science – someone with .­[email protected]) for the second ing (https://cais​­ .​ ­uga.​ ­edu). CAIS’s 40+ of Chemistry, Geography, Geology, strong interest and expertise in position, and David Paynter (David​ scientists collaborate in research and Marine Science, Ecology, and Archae- plasma processes preferably of the .­Paynter@noaa​.gov) for the third method development, serve the UGA ology. For more information go to: ­near-​­Earth space environment. We position. research community and work with https://­www​.ugajobsearch​.com/­ seek candidates interested in This position is subject to Prince­ worldwide academic institutions, postings/­175843 advanced numerical methodologies ton University’s background check government agencies, and private and models and/or in the develop- policy. companies. The Director will oversee Tenure Track Faculty Position in ment, operation, and analysis of data Princeton University is an equal scientific, fiscal and regulatory activ- Climate and Space Sciences and from related spaceborne space sci- opportunity/affirmative action ities, and work closely to develop, Engineering, University of Michigan ence instruments. We welcome employer and all qualified applicants refine, and implement a vision for The Department of Climate and applications from candidates whose will receive consideration for the Center’s continuing growth and Space Sciences and Engineering research addresses cross-­ disciplinary​­ employment without regard to age, preservation of ISO/IEC accredita- (CLaSP) in the College of Engineering areas that complement our existing race, color, religion, sex, sexual ori- tion. The Director interfaces with the at the University of Michigan in Ann strengths in space sciences and engi- entation, gender identity or expres- UGA Office of Research for policy, Arbor invites applications for a tenure neering and the development of sion, national origin, disability status, reports, and personnel administra- track faculty position with expertise space instrumentation and missions. protected veteran status, or any other tion. The Director will have a com- in one of the following areas. Although the position is open to all characteristic protected by law. mitment to a diverse workforce and 1) Essential components of the ranks, we especially seek candidates maintain a high quality of research- stressed climate ­system–​­someone at the Assistant Professor level. We Interdisciplinary ers and staff members who are com- who can bridge and strengthen our look for candidates who are capable of mitted to ­world-​­class science and existing research portfolio. Specific developing an internationally recog- The University of Georgia’s (UGA) technology. The Director provides subdisciplines of interest include nized research program, successfully Center for Applied Isotope Studies primary leadership for a robust and meteorology and climate dynamics, competing for external funding, (CAIS) is seeking a Director at the technologically advanced research polar science, atmospheric chemistry mentoring doctoral students, and rank of Assistant, Associate, or and service center that generates and air quality, clouds and water cycle participating in our educational pro- Senior Research Scientist. The CAIS annual revenues of approximately feedbacks, and impacts of climate grams at the graduate and under- is the largest isotope geochemistry/ $3M. The Director also ensures that mitigation. The department wel- graduate levels.

SCIENCE NEWS BY AGU // Eos.org 47 POSITIONS AVAILABLE

Applications should include a needs of ­dual-​­career couples. The emerging megacities like the ­Dallas-​ community engagement taking place cover letter, CV, research and teach- University is a non-­ ​­discriminatory, ­Fort Worth Metroplex become sus- in the College of Science. ing statements, a statement describ- affirmative action Employer. The tainable economic and cultural cen- Applicants should have a doctoral ing any activities, contributions, or Michigan Engineering component of ters that raise the prospects for degree in geoscience or environmen- plans related to supporting diversity, the University’s comprehensive, ­five-​ prosperity and enhance quality of tal science. Candidates in their early equity, and inclusion, and a list of ­year, DEI strategic plan can be found life. career must demonstrate strong four references with contact details. at: http://www­ ​.engin​.umich.edu/­ One of UTA’s goals is to increase potential to develop a research pro- For full consideration, applications college/­about/­diversity. the representation of historically gram supported by external funding, compiled into a single PDF should be Michigan Engineering’s vision is underrepresented faculty, including while more established candidates received before December 15th, 2020. to be the world’s preeminent college underrepresented minority faculty in must demonstrate active, externally Applications should be addressed to of engineering serving the common general and women faculty in STEM funded research agendas. ­clasp-fac-​­ search@umich​­ .edu.​ Ques- good. This global outlook, leadership fields. Increasing the representation Application Procedure tions about the position or applica- focus, and service commitment per- of faculty members who understand, Review of applications will begin tion process can be directed to the meate our culture. Our vision is sup- and have overcome, race, ­gender-​ immediately and continue until the search committee chair Chris Ruf ported by a mission and values that, ­based, and ability barriers and biases position is filled. Applicants must ([email protected]).​ The availability of together, provide the framework for is vital to the success and ­well-​­being apply online at https://​­uta​ this position is contingent upon final all that we do. Information about our of our students. Diversity is critical to .­peopleadmin​.­com/​­postings/​­13077. University approval. vision, mission and values can be academic excellence. As research A complete application includes: The University of Michigan is com- found at: http://­strategicvision.engin​ ​ demonstrates, diverse teams are 1) curriculum vitae, 2) summary of mitted to diversity, equity and inclu- .umich​.edu/. more innovative, productive, and current and proposed research (max. sion. CLaSP and the College of Engi- solve complex problems faster. UTA two pages), 3) statement of teaching neering are especially interested in The University of Texas Arlington is committed to preparing all stu- interests (max. one page), and exceptionally well qualified candidates (UTA) is spearheading a new, multi-­ ​ dents to live and work in an increas- 4) names and email addresses of who will contribute, through their ­disciplinary hiring initiative in ingly global, diverse, and intercon- three references. research, teaching, and service, to the support of our strategic plan, Bold nected world by exposing them to a Question regarding this position department’s goal of eliminating sys- Solutions | Global Impact. wide array of ideas, experiences, cul- may be directed via email to Dr. Majie temic racism and sexism by embracing UTA is uniquely positioned to tures, and individuals. Fan, College of Science Search Com- our culture of Diversity, Equity and address the epic challenges that face We are looking for strong tenure mittee (Email: mfan@uta.​­edu) or the Inclusion (DEI). Women, minorities, our growing urban regions. By lever- track faculty who will contribute in administration of the Department of individuals with disabilities, and vet- aging our expertise in the critical their geoscience or environmental Earth and Environmental Sciences erans are encouraged to apply. The areas outlined in the strategic plan, science area to the unprecedented (Courtony Hill, Email: courtony.hill@​ University is also responsive to the the University is poised to help excellence in research, teaching, and uta​.edu). PLACE YOUR AD HERE

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48 Eos // JANUARY 2021 POSTCARDS FROM THE FIELD

Hello from 14,115 feet!

My name is Lauren Haygood and I’m in the accelerated master’s geo- We made lots of great memories. Wish you all could’ve been here! science program at the University of Tulsa. In summer 2019, I attended Oklahoma State University’s field camp in Cañon City, Colo. —Lauren Haygood, University of Tulsa, Okla.

I and 60 other students were tasked with mapping different areas, mak- ing stratigraphic columns, and completing a weeklong geophysics proj- ect. This photo is from one of our field trips to Pikes Peak, which essen- View more postcards at bit.ly/Eos-postcard tially comprises a batholith composed of Pikes Peak granite.

SCIENCE NEWS BY AGU // Eos.org 3