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The
VOL. 102 | NO. 9
SEPTEMBER 2021
Career
Issue
Let these scientists inspire
you to forge a unique
path to a rewarding
profession.
Thirsty Data Centers
Iceberg Initiated
Landslides
Viking Food
Security
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FROM THE EDITOR
Editor in Chief
Heather Goss, Eos_EIC@agu.org
Charting the Paths AGU Staff
to a Scientific Career Vice President, Communications,
Marketing, and Media Relations Amy Storey
Editorial
A
small business owner, a former U.S. Navy captain, and Managing Editor Caryl-Sue Micalizio
Senior Science Editor Timothy Oleson
“the New York Times volcano guy” are just a few of the
Associate Editor Alexandra Scammell
scientists whose stories you’ll find in this issue. The News and Features Writer Kimberly M. S. Cartier
pathways to a scientific career are numerous, branching in News and Features Writer Jenessa Duncombe
many different directions from the most well-known road Production & Design
leading to an academic institution. Assistant Director, Operations Faith A. Ishii
Our special September issue highlights 17 of these pathways Production and Analytics Specialist Anaise Aristide
in our feature on page 24. Fushcia-Ann Hoover is that small Assistant Director, Design & Branding Beth Bagley
Senior Graphic Designer Valerie Friedman
business owner who took her education in science and Senior Graphic Designer J. Henry Pereira
engineering and her passion as a “maker” and used them to Graphic Design Intern Claudia Morris
launch an organization that offers consultation to communi- Marketing
ties on urban green infrastructure. Zdenka Willis, our military Assistant Director, Marketing & Advertising Liz Zipse
veteran, loved the challenge of transitioning the Navy to dig-
ital charts and went on to become the president of an international society that brings busi- Advertising
nesses, policymakers, educators, and others together to advance marine technologies.
Display Advertising Steve West
Some of these scientists followed whatever path would connect them with the outdoors. As
steve@mediawestinc.com
a child; Kristel Chanard dreamed of Himalayan expeditions. Today she’s checked off the Hima- Recruitment Advertising recruitmentsales@wiley.com
layas, the French Alps, and so many more summits to conduct her work as a research geo-
physicist for an institute in Paris. Darcy L. Peter wanted to stay closer to her Gwich’in Atha- Science Advisers
bascan home. As an environmental scientist, she’s most proud of her ability to build Geodesy Surendra Adhikari
relationships that connect Western science with Indigenous Knowledges. Meanwhile, Robin Geomagnetism, Paleomagnetism,
and Electromagnetism Nicholas Swanson-Hysell
George Andrews traveled to the volcanoes of New Zealand to get his Ph.D. but found a better Natural Hazards Paula R. Buchanan
home for his passion in writing, becoming the go-to science reporter for some of the world’s GeoHealth Helena Chapman
Atmospheric and Space Electricity Kenneth L. Cummins
biggest publications.
Cryosphere Ellyn Enderlin
Why follow a system when you can help create a better one? That’s what Aisha Morris asked Space Physics and Aeronomy Jingnan Guo
herself before leaving academia and joining the National Science Foundation, where she gets History of Geophysics Kristine C. Harper
to play a tangible role in creating a more diverse scientific community. Karen Layou, a geosci- Planetary Sciences Sarah M. Hörst
Volcanology, Geochemistry, and Petrology Emily R. Johnson
entist and professor at Reynolds Community College, is part of a movement to broaden par- Societal Impacts and Policy Sciences Christine Kirchhoff
ticipation in the sciences by highlighting the 2-year college pathway. And of course, there’s Seismology Ved Lekic
the system, and then there’s The System. Ashlee Wilkins’s passion for astronomy led her first Tectonophysics Jian Lin
Near-Surface Geophysics Juan Lorenzo
to NASA and then to the U.S. House of Representatives, where she’s a professional staff mem- Earth and Space Science Informatics Kirk Martinez
ber for the Subcommittee on Space and Aeronautics. Ocean Sciences Jerry L. Miller
Before you head over to read about these inspiring pathways, flip first to the opinion on Study of the Earth’s Deep Interior Rita Parai
Education Eric M. Riggs
page 20, where the authors deftly describe this approach to modern career pathways as a Global Environmental Change Hansi Singh
“braided river,” eschewing the old model of a pipeline. Our lives are increasingly complicated, Hydrology Kerstin Stahl
and the challenges we face as a society are increasingly complex. We all benefit from scientific Paleoceanography and Paleoclimatology Kaustubh Thirumalai
Nonlinear Geophysics Adrian Tuck
workforce development that is designed with flexibility and compassion.
Biogeosciences Merritt Turetsky
We hope you enjoy this issue and are inspired by the wide world of opportunities these sci- Hydrology Adam S. Ward
entists prove are available to everyone. Diversity and Inclusion Lisa D. White
Earth and Planetary Surface Processes Andrew C. Wilcox
©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 journals. For
permission for any other uses, contact the AGU Publications Office.
Eos (ISSN 0096-3941) is published monthly except December by AGU, 2000 Florida
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Views expressed in this publication do not necessarily reflect official positions
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Randy Fiser, Executive Director/CEO
SCIENCE NEWS BY AGU // Eos.org 1
CONTENT
Features
24 Choose Your Own Adventure
There’s no one way to be a scientist. Meet a group of 17 professionals who discovered
that their route wasn’t limited to the well-lit avenue.
On the Cover
iStock.com/georgeclerk
2 Eos // SEPTEMBER 2021
CONTENT
8 16
10 42
Columns
From the Editor Research Spotlight
1 Charting the Paths to a Scientific Career 40 The Wildfire One-Two: First the Burn,
Then the Landslides
News 41 Monitoring the Agulhas Current Through Maritime
Traffic | How Much Carbon Will Peatlands Lose
4 An Iceberg May Have Initiated a Submarine Landslide as Permafrost Thaws?
5 Tiny Kinks Record Ancient Quakes 42 Particles at the Ocean Surface and Seafloor
6 Where Do a Volcano’s Metals Go? Aren’t So Different | Establishing a Link Between Air
8 A Remarkably Constant History of Meteorite Strikes Pollution and Dementia
9 U.S. Data Centers Rely on Water from Stressed Basins 43 Gulf Stream Intrusions Feed Diatom Hot Spots
10 Getting to the Bottom of Trawling’s Carbon Emissions 44 Magma Pockets Lie Stacked Beneath Juan de Fuca
12 Dyes and Isotopes Track Groundwater from Sink Ridge
to Spring
13 Food Security Lessons from the Vikings Editors’ Highlights
15 Astronomers for Planet Earth
45 Saturn’s Dynamo Illuminates Its Interior |
16 Cyclone Tauktae Documents a Climate Trend
Understanding How Himalayan Water Towers Fill
in the Tropics
and Drain
Opinion Positions Available
17 Higher Education During the Pandemic:
46 Current job openings in the Earth and space sciences
Truths and Takeaways
20 Reimagining STEM Workforce Development
as a Braided River Postcards from the Field
49 A pair of geophysicists ride their fat-tire bikes into
the sunset to dig baseline trenches across ice wedge
polygon troughs in the Canadian High Arctic.
AmericanGeophysicalUnion @AGU_Eos company/american-geophysical-union AGUvideos americangeophysicalunion americangeophysicalunion
SCIENCE NEWS BY AGU // Eos.org 3
NEWS
An Iceberg May Have Initiated a Submarine Landslide
For further evidence that the iceberg initi-
ated the landslide, the researchers went
back to the core samples they had collected in
2018 near the landslide but before it occurred.
By analyzing the sediment composition and
the slope of the seafloor, they found that
the sediment in the area was stable under
gravitational load, but the estimated load
of the iceberg would have been enough to ini-
tiate the slide.
Morelia Urlaub, a marine geoscientist
at GEOMAR Helmholtz Centre for Ocean
Research Kiel in Germany who wasn’t involved
in the study, is researching ways to monitor
the seafloor and identify new landslides. She
said that when studying submarine land-
slides, researchers must be in the right place
The CCGS Hudson sails in front of an iceberg that scientists later found had initiated a submarine landslide in at the right time. “That’s what I found fasci-
Southwind Fjord, Baffin Island. Credit: Alex Normandeau nating about this iceberg study. They basi-
cally caught one,” Urlaub said. “The study is
important because it brings up a new mech-
anism and because the observation is as good
I
n August 2018, Alexandre Normandeau was within a short time window and determine as it gets.”
on a research cruise in the Southwind Fjord what might have caused it.
of Canada’s Baffin Island, attempting to Because no earthquakes had occurred Iceberg Impacts Run Deep
study landslides on the seafloor. Norman- within 300 kilometers of Southwind Fjord, the After discovering the landslide in Southwind
deau, a research scientist at the Bedford researchers looked for other mechanisms. By Fjord, the researchers explored maps of the
Institute of Oceanography in Dartmouth, comparing the bathymetry data from their seafloor in other locations. They found several
N. S., was aboard the CCGS Hudson collecting two visits to the fjord, they found an intrigu- other iceberg pits at landslide head scarps.
bathymetry data and core samples of the sea- ing piece of evidence. They noticed a charac- “The most surprising result was off the con-
floor when the crew spotted an iceberg. “We teristic pit left when an iceberg strikes the tinental slope of Nova Scotia,” Normandeau
took a bunch of photos and didn’t think any- seafloor—right at the initiation point of the said. “They’re much bigger [landslides] than
thing of it at the time,” Normandeau remem- landslide—known as a head scarp. Using sat- what we see in the fjords.” Normandeau
bered. ellite images from S entinel-2, they realized hypothesized that when there was an ice
A year later, Normandeau and his col- sheet in the region around 20,000 years ago,
leagues determined that that same iceberg big icebergs broke off and struck the seabed,
may have initiated a new submarine land- causing landslides. He’s hoping to address
slide. Scientists had never shown before that “We were hoping for this hypothesis in future research.
icebergs could cause landslides. Their find- As climate change causes more icebergs to
ings were published in Nature Geoscience (bit something like this. But to break off existing ice sheets, understanding
.ly/iceberg-landslides). see it happen? It was a lot the risks that icebergs pose could mitigate
damage to new infrastructure projects. In
An Iceberg Aground of luck.” Canada, there is a push to connect northern
Submarine landslides can threaten sea life, communities with subsea Internet cables,
cause tsunamis, and damage infrastructure which would be especially at risk. But ice-
such as subsea Internet cables. bergs can also travel thousands of kilome-
Despite these risks, scientists don’t fully that the iceberg they saw the year before ters, potentially causing landslides far from
understand the causes of submarine land- eventually ran aground. A few days later, it the Arctic. “It’s important to be aware of the
slides. In some cases, earthquakes are the capsized and slammed into the ocean floor, triggering mechanisms when we’re planning
culprits. But because most of the ocean floor regrounding several meters away. seafloor infrastructure,” Normandeau said.
is irregularly mapped, it is difficult to know “We interpret that it’s that impact that cre- The gouges left when icebergs collide with
when landslides occur and to link them with ated the landslide, because when you look at the seafloor might be only the tip of the
a causal event. where the iceberg regrounded, that’s exactly problem.
When the researchers returned to South- where the landslide head scarp is,” said Nor-
wind Fjord in 2019, they learned that a new mandeau. “We were hoping for something
landslide had occurred since their previous like this. But to see it happen? It was a lot of By Andrew Chapman (@andrew7chapman),
visit, providing a rare opportunity to look luck.” Science Writer
4 Eos // SEPTEMBER 2021
NEWS
Tiny Kinks Record Ancient Quakes
E
very so often, somewhere beneath our Micas—sheetlike minerals that can stack thin section), Anderson and his colleagues
feet, rocks rupture and an earthquake together in individual crystals that often pro- compared kink bands from two locations in
begins. With big enough ruptures, we vide the sparkle in kitchen countertops—can Maine, both more than 300 million years old.
might feel an earthquake as seismic waves preserve deformation features that look like The first location is rife with telltale signs of
radiate to or along Earth’s surface. However, microscopic chevrons. On geology’s mac a dynamically deformed former seismogenic
a mere 15%–20% of the energy needed to roscale, chevrons form in layered strata. In zone, like shattered garnets and pseudo-
break rocks in the first place translates into minuscule sheaves of mica, petrologists tachylyte. The second location exposes rocks
seismicity, scientists suspect. observe similar pointy folds because the that changed slowly, under relatively static
The remaining energy can dissipate as fric- structure of the mica leaves it prone to kink- conditions.
tional heat, leaving behind planes of glassy ing, rather than to buckling or folding, said
rock called pseudotachylyte. The leftover Frans Aben, a rock physicist at University
energy may also fracture, pulverize, or deform College London.
rocks that surround the rupture as it rushes In a new article in Earth and Planetary Sci-
With micas, once they’re
through the crust, said Erik Anderson, a doc- ence Letters, Anderson and his colleagues
toral student at the University of Maine. argue that these microstructures—called kinked, they will remain
Because these processes occur kilometers
below Earth’s surface, scientists cannot
kink bands—often mark bygone earthquake
ruptures and might outlast other indicators
kinked, preserving records
directly observe them when modern earth- of seismicity (bit.ly/kink-bands). of ancient earthquakes in
quakes strike. Shear zones millions of years
old that now reside at the surface can provide Ancient Kink Bands,
the hearts of mountains.
windows into the rocks around ancient rup- Explosive Explanation
tures. However, although seismogenically To observe kinked micas, scientists must
altered rocks remain at depth, heat and pres- carefully cut rocks into slivers thinner than
sure can erase clues of past quakes, said the width of a typical human hair and affix Comparing the geometry of the kink bands
Anderson. “We need some other proxy when each rock slice to a piece of glass. By using from these sites, the researchers observed
we’re looking for evidence of earthquakes in high-powered microscopes to examine this differences in the thicknesses and symme-
the rock record.” rock and glass combination (aptly called a tries of their microstructures. In particular,
samples from the dynamically deformed
location displayed thin-sided, asymmetric
kinks. The more statically deformed samples
showcased equally proportioned points with
thicker limbs.
Kink bands, said Aben, can be added to a
growing list of indicators of seismic activity
in otherwise cryptic shear zones. The data, he
said, “speak for themselves.” Aben was not
involved in this study.
To further cement the link between earth-
quakes and kink band geometry, Anderson
and colleagues analyzed 1960s era studies
largely driven by the development of nuclear
weapons. During that time, scientists strove
to understand how shock waves emanated
from sites of sudden, rapid, massive pertur-
bations like those produced at nuclear test
sites or meteor impact craters. Micas devel-
oped kink bands at such sites, as well as in
complementary laboratory experiments, said
Anderson, and they mimic the geometric
patterns produced by dynamic strain rate
events—like earthquakes. “[Kink band]
geometry,” Anderson said, “is directly linked
to the mode of deformation.”
Stressing Rocks, Kinking Micas
A kinked muscovite grain embedded within a fi ne-grained, highly deformed matrix of other minerals displays In addition to exploring whether kinked mica
asymmetric kink bands. Credit: Erik Anderson geometry could fingerprint relics of earth-
SCIENCE NEWS BY AGU // Eos.org 5
NEWS
quake ruptures, Anderson and his colleagues
estimated the magnitude of localized, tran-
Where Do a Volcano’s Metals Go?
sient stress their samples experienced as
H
an earthquake’s rupture front propagated awaii’s Kılauea volcano is very large, like cerium, remain for much longer. “It was
through the rocks, he said. In other words, he very active, and very disruptive. Its quite striking to see that there is such a large
asked, might the geometry of kinked micas recent activity belched tons of sulfur difference,” said Ilyinskaya. “That’s some-
scale with the magnitude of momentary dioxide into the air each day. But aside from thing we didn’t really expect.”
stress that kinked the micas in the first place? gases, eruptions from basaltic volcanoes like
Kılauea release metals and metalloids, includ-
ing ones considered pollutants, like copper,
zinc, arsenic, and lead. These metal pollut- “Kīlauea is a wonderful
ants have been found in the ground, water,
The stresses experienced rain, snow, and plants near vents posterup- natural laboratory for
by these rocks…were about tion, as well as in the air downwind. studying volcanism and
But how these volcanic metals are trans-
9 times the pressure at the ported from active eruptions, their longevity particularly that type of
Mariana Trench. in the environment, and how much and basaltic volcanism.”
where they end up settling were open ques-
tions until recently. “We know that volcanoes
are a huge natural source of these metals,
which are environmentally very important,”
By extrapolating data from previously pub- said Evgenia Ilyinskaya, an associate profes- The researchers think that metal deposi-
lished laboratory experiments, Anderson sor at Leeds University in the United King- tion may be very sensitive to atmospheric
estimated that pulverizing rocks at the deep- dom. “But there’s just not very much known conditions like wind, rain, and humidity. Dif-
est depths at which earthquakes can nucleate about what happens to them after emission— ferent environments could mean different
requires up to 2 gigapascals of stress. how long do they stay in the atmosphere, and patterns of volcanic metal dispersal and pol-
Although stress doesn’t directly correspond where do they go?” lution. For example, drier and colder environ-
to pressure, 2 gigapascals is equivalent to ments, like Iceland, may have patterns dif-
more than 7,200 times the pressure inside a Sampling the Wind ferent than hot and humid environments like
car tire inflated to 40 pounds per square inch. To better understand how concentrations of Hawaii.
For reference, the unimaginably crushing metals change as a plume travels downwind
pressure in the deepest part of the ocean— during an active ongoing eruption, Ilyinskaya
the Mariana Trench—is only about 400 times and fellow researcher and University of Cam-
the pressure in that same tire. bridge doctoral student Emily Mason set up
By the same conversion, kinking micas sampling stations around the Big Island of
requires stresses 8–30 times the water pres- Hawaii. Intermittently over the course of
sure in the deepest ocean. Because Anderson almost a year, they collected samples as close
found pulverized garnets proximal to kinked as possible to Kılauea’s eruptive vent and at
micas at the fault-filled field site, he and his another six sites around the island. The far-
colleagues inferred that the stresses momen- thest site was more than 200 kilometers dis-
tarily experienced by these rocks as an earth- tant, and all were in the path of the trade
quake’s rupture tore through the shear zone wind. They also collected samples 300 meters
were about 1 gigapascal, or 9 times the pres- above the plume using a drone.
sure at the Mariana Trench. “Kılauea is a wonderful natural laboratory
Aben described this transient stress esti- for studying volcanism and particularly that
mate for earthquakes as speculative, but he type of basaltic volcanism,” said Mason. “It’s
said the new study’s focus on e arthquake- a well-understood system, and that makes it
induced deformation fills a gap in research a very appealing target.”
between very slow rock deformation that Their research, published in Communica-
builds mountains and extremely rapid defor- tions Earth and Environment, is the biggest
mation that occurs during nuclear weap- study of volcano metal emissions ever done
ons testing and meteor impacts. And with (bit.ly/volcano-metal-emissions).
micas, he said, “once they’re kinked, they Ilyinskaya, Mason, and their colleagues
will remain kinked,” preserving records of found an enormous difference between pol-
ancient earthquakes in the hearts of moun- lutant levels during and after the eruption—
tains. up to 3 times higher than periods without vol-
canic activity. They discovered that different
pollutants fall out at different rates: Some A researcher wearing protective gear walks toward
By Alka Tripathy-Lang (@DrAlkaTrip), Science pollutants, like cadmium, remain in the a laze plume created by Kīlauea’s lava entering the
Writer plume for only a few hours, whereas others, ocean. Credit: Evgenia Ilyinskaya/USGS
6 Eos // SEPTEMBER 2021
NEWS
Researchers working at Kīlauea’s still-active fissure 8, located on the volcano’s lower East Rift Zone. Credit: Emma Liu/USGS
Laze Plumes and Copper fact that copper emissions could be compa- living close to the volcano,” she said. “On the
Mason also studied laze plumes, created when rable between the laze plume and the mag- other hand, it may be lessening the impact on
the heat of lava very quickly evaporates sea- matic plume is definitely surprising to me,” the communities further away.”
water, by taking samples where the lava said Mason. Volcanic pollutants have been linked to
entered the ocean. The phenomenon is rela- Volcanologist and geochemist Tobias health problems like thyroid cancer, multiple
tively rare, as there aren’t that many basaltic Fischer of the University of New Mexico, who sclerosis, and respiratory diseases. One goal
volcanoes near sea level where lava can reach was not involved in either study, said this of studies like Ilyinskaya’s and Mason’s is to
the ocean. But laze plumes are worth study- research is “a really nice approach and really create a pollution map that models where the
ing, said Mason, because historically there advances our understanding of not only the plume will go, the concentrations of metals,
have been much larger basaltic eruptions that quantity of metal emissions but also their life and the atmospheric conditions, to help com-
created large igneous provinces, like the Dec- cycle in a volcanic plume like this one.” munities avoid exposure. Fischer said a pol-
can Traps. These eruptions may have released lution map would be a wonderful contribu-
tons of metals and metalloids into the sur- Health Risks tion. “Then you can probably make some
rounding environment. “It’s possible that At some point during the 3 hours the plume pretty good predictions of where you get high
laze plumes are a slightly underestimated took to reach the closest sampling station, concentrations of metal deposition and what
force in those events,” said Mason. its metals were radically depleted. The kinds of metals,” he said.
The amount of copper being released by researchers hypothesized that the h eavy- More research needs to be done on how
laze plumes is surprising, said Mason. Sea- metal pollutants may have formed a very metals are stratified within a plume and also
water is rich in chlorine, and she thinks it water soluble chemical species that fell out their long-term accumulations in water and
enables more copper to de-gas. Laze plumes in rain close to the eruption site. Ilyinskaya is plants, said Mason. “Volcanic metals are an
could even release more copper into the envi- collecting samples from Iceland’s Fagradals- insidious threat in terms of the way that they
ronment than large magmatic plumes, she fjall volcano to learn more about what hap- build up in the environment,” said Mason.
said. This copper would also be released pens in those first 3 hours of a plume’s life-
directly into the ocean and could affect time.
marine environments, by either worsening “If this process is really happening, then it By Danielle Beurteaux (@daniellebeurt),
ocean acidification or adding nutrients. “The could be disproportionately impacting people Science Writer
SCIENCE NEWS BY AGU // Eos.org 7
NEWS
A Remarkably Constant History of Meteorite Strikes
T
housands of tons of extraterrestrial
material pummel Earth’s surface each
year. The vast majority of it is too small
to see with the naked eye, but even bits of
cosmic dust can reveal secrets.
By poring over more than 2,800 grains from
micrometeorites, researchers have found that
the amount of extraterrestrial material falling
to Earth has remained remarkably stable over
millions of years. That’s a surprise, the team
suggested, because it’s long been believed
that random collisions of asteroids in the
asteroid belt periodically send showers of
meteoroids toward Earth.
Astronomy by Looking Down When asteroids collide, Earth doesn’t always experience an uptick in meteorite strikes. Credit: iStock.com/
Birger Schmitz, a geologist at Lund University dottedhippo
in Sweden, remembers the first time he
looked at sediments to trace something that
had come from space. It was the 1980s, and
he was studying the Chicxulub impact crater. impressive, said Terfelt, who recalled black meteorites. But of the 15 of these titanic tus-
“It was the first insight that we could get smoke filling their laboratory’s fume hood. sles involving chromite-bearing asteroids
astronomical information by looking down “The reaction between pyrite and nitric acid that occurred over the past 500 million years,
instead of looking up,” said Schmitz. is quite spectacular.” that was the case only once, Schmitz and Ter-
Inspired by that experience, Schmitz and The chemical barrage left behind grains of felt showed. “Only one appears to have led
his Lund University colleague Fredrik Terfelt, chromite, an extremely hardy mineral that to an increase in the flux of meteorites to
a research engineer, have spent the past composes about 0.25% by weight of some Earth,” said Schmitz.
8 years collecting more than 8,000 kilograms meteorites. These grains are like a corpse’s Perhaps asteroid collisions need to occur in
of sedimentary limestone. They’re not inter- gold tooth, said Schmitz. “They survive.” a specific place for their refuse to actually
ested in the rock itself, which was once part Schmitz and Terfelt found that more than make it to our planet, the researchers propose
of the ancient seafloor, but rather in what it 99% of the chromite grains they recovered in the Proceedings of the National Academy of
contains: micrometeorites that fell to Earth came from a stony meteorite known as an Sciences of the United States of America (bit.ly/
over the past 500 million years. ordinary chondrite. That’s perplexing, the a steroid -c ollisions). So-called Kirkwood
researchers suggested, because asteroids of gaps—areas within the asteroid belt where
this type are rare in the asteroid belt, the the orbital periods of an asteroid and the
source of most meteorites. “Ordinary chon- planet Jupiter constitute a ratio of integers
Some of the reactions that dritic asteroids don’t even appear to be com-
mon in the asteroid belt,” Schmitz told Eos.
(e.g., 3:1 or 5:2)—are conspicuously empty.
Thanks to gravitational interactions that
ensued were impressive, An implication of this finding is that most asteroids experience in these regions
said Terfelt, who recalled of Earth’s roughly 200 known impact struc-
tures were likely formed from ordinary chon-
of space, they tend to get flung out of those
orbits, said Philipp Heck, a meteorist at the
black smoke filling their drites striking the planet. “The general view Field Museum of Natural History in Chicago
has been that comets and all types of aster- not involved in the research. “Those objects
laboratory’s fume hood. oids were responsible,” said Schmitz. tend to become Earth-crossing relatively
When Schmitz and Terfelt sorted by age the quickly.”
2,828 chromite grains they recovered, the We’re gaining a better understanding of
mystery deepened. The distribution they the solar system by studying the relics of
Dissolving Rocks found was remarkably flat except for one peak asteroids, its oldest constituents, said Heck.
Schmitz and Terfelt used a series of strong roughly 460 million years ago. We were sur- But this analysis should be extended to other
chemicals in a specially designed laboratory prised, said Schmitz. “Everyone was telling types of meteorites that don’t contain chro-
to isolate the extraterrestrial material. They us [we would] find several peaks.” mite grains, he said. “This method only looks
immersed their samples of limestone—rep- at certain types of meteorites. It’s far from a
resenting 15 different time windows spanning Making It to Earth complete picture.”
the Late Cambrian to the early Paleogene—in Sporadic collisions between asteroids in the
successive baths of hydrochloric, hydroflu- asteroid belt produce a plethora of debris, and
oric, sulfuric, and nitric acid, to dissolve the it’s logical to assume that some of that cos- By Katherine Kornei (@KatherineKornei),
rock. Some of the reactions that ensued were mic shrapnel will reach Earth in the form of Science Writer
8 Eos // SEPTEMBER 2021NEWS
U.S. Data Centers Rely on Water from Stressed Basins
T
hanks to our ever increasing reliance Connecting Water Consumption Agency and the U.S. Energy Information
on the Internet, the amount of data to Data Centers Association, and data from previous academic
online is skyrocketing. The global data The researchers identified more than 100,000 studies, the researchers matched the data
volume is expected to grow sixfold from 2018 data centers using previously collected infor- centers with their most likely sources of elec-
to 2025. It might seem like that information mation from the Lawrence Berkeley National tricity and water. Then they estimated the
is swirling in the cloudy sky, but it’s actually Laboratory and the websites of commercial data centers’ annual energy, direct water, and
stored in physical data centers. data centers. While most of the data centers indirect water consumption based on their
Landon Marston, an assistant professor at are small operations run by individual com- energy and cooling requirements. By piecing
Virginia Polytechnic Institute and State Uni- panies, the majority of servers in the United all this information together, “we can have a
versity, recently noticed news articles States are housed in fewer than 2,500 “colo- spatially explicit representation of the envi-
addressing the growing energy requirements cation” and “hyperscale” data centers, which ronmental footprints associated with each of
of the data center industry. As an expert in store data for many companies and the public the data centers,” said Marston.
water resources engineering, he wondered simultaneously. Hyperscale data centers are They mapped the U.S. data center indus-
how those energy requirements translated the biggest type of data center, typically try’s carbon footprint, water footprint, and
into water consumption. “We know data cen- housing more than 5,000 servers, but are water scarcity footprint. The latter calculates
ters use a lot of energy, and energy uses a lot designed to be more energy efficient by using the pressure that water consumption puts on
of water. So how much water is being used?” cutting-edge cooling methods and servers. a region based on local water availability and
said Marston. “We suspected that there could All data centers consume water directly to needs.
be large impacts at a very local scale, but there cool the electronics at the site and indirectly,
hadn’t really been a spatially detailed analy- through electricity generation at the power Hot, Dry, and Hydroelectric
sis looking at the environmental impact of plants that service the sites. Using records The results revealed that data centers use
data centers.” from the U.S. Environmental Protection water from 90% of watersheds in the United
In a study recently published in Environ- States. The water consumption of individual
mental Research Letters, Marston and col- data centers varies dramatically depending
leagues attempted to map how and where on where they are located and their electric-
data centers in the United States consume
energy and water (bit.ly/data-center-energy).
“We know data centers use ity source. For example, data centers in the
Southwest rely on w ater-heavy hydroelec-
The results showed that it takes a large a lot of energy, and energy tric power, and the hot climate there leads to
amount of water to support the cloud and more evaporation compared with other
that the water often comes from w ater-
uses a lot of water. So how regions in the country. Data centers in the
stressed basins. much water is being used?” cooler, wetter climates of the East Coast also
tend to use more solar and wind energy,
which require less water.
Of the total water footprint attributed to
data centers, 75% was from indirect water use
at power plants and 25% was from on-site
water use. “This is important, because most
[data center] operators don’t really look at
their power consumption as part of the over-
all water footprint,” said David Mytton, a
researcher at Imperial College London and a
member of the Data Center Sustainability
Research Team at the Uptime Institute. Myt-
ton was not involved in the new study.
A. B. Siddik, a graduate student at Virginia
Tech and the study’s lead author, explained
that on-site water consumption has a bigger
impact on the water scarcity footprint, indi-
cating that many data centers are in water-
stressed regions. “Most often they are in the
middle of a desert, or in the Southwest, like
California, Nevada, and Arizona,” said Siddik.
“Those are hubs of data centers.” The overall
water scarcity footprint was more than double
the water footprint, suggesting that data cen-
ters in the United States disproportionately
A Google data center in Council Bluffs, Iowa. Credit: Chad Davis, CC-BY-2.0 (bit.ly/ccby2-0) consume water from water-stressed regions.
SCIENCE NEWS BY AGU // Eos.org 9NEWS
Planning for the Digital Future
As the demand for data storage grows, so
Getting to the Bottom of Trawling’s
will the need for hyperscale data centers.
Although these buildings are more efficient
Carbon Emissions
than smaller data centers, concentrating the
energy and water demands in fewer locations
could tax the local environment.
Further innovations in energy-efficient
technology and investments in renewable
energy will help curb energy and water usage,
but Marston also recommended building new
data centers in regions with smaller carbon
and water-scarcity footprints. “Simple real
estate decisions could potentially be the solu-
tion here,” he said.
Technology companies have already tried
extreme locations for data centers. For exam-
ple, Google converted an old mill in frigid
“Simple real estate
decisions could potentially
be the solution here.”
Trawling nets like these disturb delicate ocean floor ecosystems and inadvertently release stored carbon. Credit:
Alex Proimos, CC BY 2.0 (bit.ly/ccby2-0)
northern Finland into a data center, and Mic-
rosoft experimented with putting data cen-
ters in the ocean. But according to the study,
B
locations such as New York and southern ottom trawling, a controversial fish- tizing the creation of marine protected areas
Florida that have an abundance of water and ing practice in which industrial to restore ocean biodiversity and maximize
renewable energy sources would have a lower boats drag weighted nets through the carbon storage and ecosystem services (bit.ly/
environmental impact. water and along the ocean floor, can unin- framework-mpa).
Mytton agreed that it’s important to con- tentionally dig up seafloor ecosystems and
sider the locations of future data centers, release carbon sequestered within the sedi-
adding that climate change complicates these ments. For the first time, researchers have
decisions because places that are not water attempted to estimate globally how this
stressed now might become drier and hotter fishing technique may be remineraliz-
“The ocean is one of our
over time. Plus, many other factors contribute ing stored carbon that, as the seabed is tilled, biggest carbon sinks, so
to where data centers are built, such as the ends up back in the water column and pos-
local taxes, regulations, and workforce. Stra- sibly the atmosphere, where it would con-
when we put in more
tegically placing data centers based on water tribute to climate change. human-induced CO2
resources is also an important economic con- “The ocean is one of our biggest carbon
sideration for the industry, Marston said, sinks,” said Trisha Atwood, who researches
emissions…we’re
because water-stressed regions are prone to aquatic ecology at Utah State University. “So weakening that sink.”
electricity blackouts and brownouts, which when we put in more h uman-induced CO2
are detrimental to the operation of data cen- emissions, whether that’s directly dumping
ters. CO2 into deep waters or whether that’s trawl-
“Data [are] so critical to the way our society ing and enhancing remineralization of this
functions, and data centers underpin all carbon, we’re weakening that sink.” Estimating Carbon Loss
that,” Marston said. “It’s not just about the Atwood helped build a model that shows from the Ocean Floor
environmental footprint. It’s also a potential that bottom trawling may be releasing as To create the model, Atwood and her coau-
risk for these data centers. much as 1.5 billion metric tons of aqueous thors first needed to figure out how much of
carbon dioxide (CO2) annually, equal to what the ocean floor is dredged by trawlers. They
is released on land through farming. Her work turned to data from the nonprofit Global
By Andrew Chapman (@andrew7chapman), was part of a paper recently published in Fishing Watch, which recently began tracking
Science Writer Nature that presents a framework for priori- fishing activity around the world, and com-
10 Eos // SEPTEMBER 2021NEWS
piled data on industrial trawlers and dredg-
ers from 2016 to 2019.
The next step was to find data on how
much carbon is stored in the world’s ocean
sediments. Because that information was not
readily available, Atwood and colleagues built
a data set by analyzing thousands of sedi-
ment cores that had been collected over the
decades.
Last, they dug through the scientific liter-
ature, looking at studies that examined
whether disturbances to the soil in coastal
ecosystems, such as seagrasses, mangroves,
and salt marshes, exposed carbon that was
once deep in marine sediments and enhanced
carbon production in the ocean.
“We lean really heavily on that literature,”
said Atwood. “We used a lot of the equations
[in previous papers] to build our model and
extend it into the seabeds in these more open
ocean locations. And from there, we were able
to come up with this first estimate.”
“We in no way intended A group of twin-rigged shrimp boats trawl the northern Gulf of Mexico off the coast of Louisiana. The trawlers are
our model to be the end-all trailed by plumes of sediment, suggesting that their nets are scraping the seafloor. Credit: SkyTruth Galleries,
CC BY-NC-SA 2.0 (bit.ly/ccbyncsa2-0)
in the trawling
conversation. We hope that
many more studies will Existing Trawling Data pointed to several studies, including one she
come along that help May Be Too Scant was a part of that showed loss of organic car-
Not everyone, however, is convinced that bon through erosion.
produce more localized Atwood and Sala’s model on bottom trawling “I want to emphasize that [the authors]
results.” and loss of carbon sequestration in marine address a very important issue regarding how
sediments is accurate. Sarah Paradis, who is bottom trawling, a ubiquitous and very poorly
studying the effects of bottom trawling on regulated anthropogenic activity, is affecting
the seafloor for her Ph.D. at the Institute of the seafloor,” she wrote. “But the values they
Environmental Science and Technology in propose are far from being credible.”
Their investigation did not attempt to Barcelona, is skeptical. Atwood disagreed. “We don’t need lots of
determine whether sequestered carbon that In an email to Eos, Paradis noted that since studies on the effects of trawling because we
has been released by bottom trawling remains the 1980s, fewer than 40 studies have built our model using decades of carbon
in the water column or is released into the addressed the impacts that bottom trawling cycling research,” she wrote in an email to
atmosphere, although they noted potential has on sedimentary organic carbon. These Eos. “Trawling is simply a perturbation that
problems either way. In the paper, the few studies are not enough to build a model mixes and re-suspends sediments, leading to
authors note that it is likely to increase ocean on, she said, and in addition, the studies increases in carbon availability. All we needed
acidification, limit the ocean’s buffering reached different conclusions. Some studies to know about trawling to apply a carbon
capacity, and even add to the buildup of observed that bottom trawling decreased model to it is where trawling occurs and how
atmospheric CO2. organic carbon content of the seafloor, deep in the sediment the trawls go.”
Atwood and the lead author of the paper, whereas others showed that it increased In addition, Atwood said, “We in no way
Enric Sala, a conservation ecologist who is organic carbon. intended our model to be the end-all in the
also a National Geographic E xplorer-in- In addition, Paradis wrote that less organic trawling conversation. We hope that many
Residence, are working with Tim DeVries, carbon on the seafloor does not necessarily more studies will come along that help pro-
who studies ocean biogeochemistry at the mean its remineralization to CO2. Rather, it duce more localized results.”
University of California, Santa Barbara, and could simply mean loss of organic carbon
scientists at NASA’s Goddard Space Flight through erosion, which means that the car-
Center to build atmospheric models to try to bon moves to another area of the seabed but By Nancy Averett (@nancyaverett), Science
figure out where the released carbon goes. very little is remineralized into CO 2. She Writer
SCIENCE NEWS BY AGU // Eos.org 11NEWS
Dyes and Isotopes Track Groundwater from Sink to Spring
published in Groundwater (bit .ly/sinkhole
-spring). But when studying sinkholes, he
said, scientists have to consider surface water
flows, too.
In 2010, two sinkholes appeared at the edge
of Lake Miccosukee in north central Florida,
and in 2018 Ye and his colleagues used a tech-
nique called dye tracing to detect water flows
from sinkhole to spring.
Dye tracing requires guesswork, Ye said.
It’s “like hunting a treasure.”
Florida Geological Survey technicians
poured lime-green fluorescein dye into the
sinkholes, then placed monitors at likely out-
flow sites downslope. None detected the
diluted dye. The researchers also placed
cheaper charcoal packets at less likely loca-
tions. One of those sites, Natural Bridge
Spring, 32 kilometers away, turned up evi-
dence of the dye.
The method would remove
the guesswork of dumping
dye into a sinkhole and
expand the understanding
of the karst aquifer at
lower cost and effort.
Tom Greenhalgh introduces tracer dye into a sinkhole at Lake Miccosukee. Credit: Ming Ye
B
eneath Florida’s cities and swamps lies understanding is important to populations Heavy Signatures
a complex network of karst conduits. outside Florida: Karst aquifers provide drink- Connecting the dots with dye was only step
The same chemical weathering that ing water for 25% of people on Earth. one. The team next explored whether iso-
carves truck-sized tunnels through the cal- Isotope analysis helps hydrogeologists topes could also establish the hydraulic con-
cium carbonate rock also leads to sinkholes trace water origins, but the technique’s use nection.
at the surface. For Florida insurance agents, generally has been limited to sinkhole lakes Isotope signatures are a common method
sinkholes are a headache. But for the state’s and springs no more than 4 kilometers apart. for assessing groundwater origins. A small
hydrogeologists, every sinkhole is an oppor- Recently, however, a team in Florida used iso- percentage of oxygen molecules are 18O,
tunity to understand the aquifer below. tope ratios to connect points 32 kilometers “heavy isotopes” that evaporate less readily
Sinkholes allow surface water, as well as apart. It’s the farthest hydraulic connection than common 16O isotopes, giving lake signa-
contaminants, to flood into an aquifer. By between a sinkhole and a spring yet docu- tures a substantially higher proportion of 18O
mapping the network of entry points and exit mented and the first connection involving a than groundwater or rainfall. Knowing the
springs, hydrogeologists can better under- first-magnitude spring (a spring discharging isotope signatures of the sinkhole, spring,
stand the underground system and better an average of 100 cubic feet—2.8 cubic and groundwater, the researchers determined
protect drinking water at its source. That meters—of water per second). that roughly 8.5% of Natural Bridge Spring
water originated at Lake Miccosukee.
“Dyeing” to Know That mixing fraction was based on pairs of
“Normally, for hydrogeology, we only care water samples. Using weekly water samples,
u Read the latest news about subsurface water flows,” explained the researchers compared isotopes from Nat-
at Eos.org Ming Ye, a hydrogeologist at Florida State ural Bridge Spring to isotopes collected earlier
University and a coauthor of the research, at Lake Miccosukee. They found that the dye
12 Eos // SEPTEMBER 2021NEWS
reached the spring 18 days after application
at Lake Miccosukee, and the presence of the
Food Security Lessons
dye at Natural Bridge Spring peaked at
day 34. Removing the effects of rainfall, the
from the Vikings
isotope ratios at both sites were perfectly cor-
related 35 days apart, demonstrating a
hydraulic connection and validating the
expected transit time.
Connecting Dots Underground
The researchers now plan to reverse the pro-
cess, tying a spring back to its source and
using isotopes as a primary confirmation
method.
By collecting regular water samples from
area springs and sinkhole lakes, researchers
can look for isotope ratio trends over time.
Possible connections can be confirmed with
dye tracing. The method would remove the
guesswork of dumping dye into a sinkhole
and expand the understanding of the karst
aquifer at lower cost and effort, researchers
said.
“What they’re exposing here is a very
sound method to backtrack type of infiltra-
tion,” said Joanna Doummar, an assistant
professor of hydrogeology at American Uni-
versity of Beirut who was not involved in the
research.
Using isotopes to connect the dots allows
hydrogeologists a wider window of sampling
and evidence. “[Dye] tracing is very import- Viking and p
re-Viking agricultural practices (as presented here in the living history of Fotevikens Museum in Swe-
ant, but it’s very static,” said Doummar. “It den) were influenced by climate and may help modern communities adjust to climate change. Credit: Fährten-
doesn’t tell you how this is varying through leser/Wikimedia
time.”
Ultimately, knowledge of the subsurface
system will help water managers protect
F “Our findings
spring water at its upslope entry point. arming practices of the Vikings and
Knowing the transit time and the mixing their ancestors could provide inspira-
fraction will also help managers gauge tion for resilient food systems today. demonstrate that climate
threats, as contaminants may decay or dilute This is thanks to a study exploring how Scan- already changed in the
while traveling through the aquifer. dinavian societies adapted their agricultural
“It’s really important, given the heteroge- activities in a period of European history past—it is not something
neity of this infiltration, to detect all these marked by stark climate fluctuations.
new—and societies had to
areas and identify all the transit times,” The Viking Age kicked off around 800 CE as
Doummar said. “With the assumptions that societies in Scandinavia expanded, partly as adapt to it already 1,500
[Ye and his team] have taken, which are very
legitimate, they have exposed a method to
a result of a rise in temperature that allowed
agriculture to flourish. Historians believe that
years ago.”
backtrack the percentage of water coming a growth in population and the pressure it
from the sinkhole.” placed on available farmland were reasons
Until the system is developed, Ye and his Vikings began venturing beyond their home-
collaborators will continue treasure hunting. lands. Less is known about farming practices in
A 1 ,618-hectare Florida lake completely In popular culture today, a lot of focus is re-Viking societies, those existing in an era
p
drained into a sinkhole in early June, offering placed on Viking raids and attacks on reli- known as the Dark Ages Cold Period. During
another chance to explore the aquifer with gious sites, partly because many firsthand this half millennium between 300 and 800
bags of organic dye. accounts were written by besieged Christian CE, northern Europe experienced cold cli-
scholars. But archaeological evidence sug- mates driven by volcanoes spewing gases and
gests that above all else, Vikings were agri- dust into the atmosphere, which reduced the
culturalists who cultivated crops and reared amount of solar radiation reaching Earth’s
By J. Besl (@J_Besl), Science Writer livestock, often on self-sufficient farms. surface.
SCIENCE NEWS BY AGU // Eos.org 13NEWS
more biotic activity in the lake, which resulted
in a greater accumulation of calcium carbon-
ate deposits on the lake bed.
The key finding was that warmer phases
were dominated by the cultivation of crops,
whereas cooler phases were dominated by
livestock farming. Manon’s team, as well as
archaeologists working at Rakni’s mound,
suggested that it is not surprising that farm-
ers would rely more on animals during colder
periods (when crop yields are reduced) and
are reexamining archaeological evidence to
support this theory.
Pollen grains in the core revealed the types
and extents of staple crops, which included
Constructed between the 5th and 6th centuries, Rakni’s mound is one of the largest barrows in northern Europe rye, wheat, and barley. Overall, cold periods
and near the site of new research into the farming practices of pre-Viking societies. Credit: Øyvind Holmstad/ corresponded to reduced crop yields, with
Wikimedia, CC BY-SA 3.0 (bit.ly/ccbysa3-0) barley being the most affected by climate
shifts.
Animal grazing near the lake was inferred
from the core’s quantity of Sordaria, fungi that
Digging in the Mud ern Europe. Previous archaeological studies thrive on animal feces. Small quantities of
Near Rakni’s Mound have dated the mound’s construction to the DNA recovered from the core also revealed
The new research finds evidence that a com- mid-6th century and found extensive evi- the presence of cows, pigs, and sheep.
munity in Norway responded to this climate dence of farming and food preparation activ-
turbulence by regularly adapting its cereal ities in the area. Strategic Farmers
production and animal husbandry practices. Bajard and her colleagues steered a raft Bajard said Viking ancestors may have stra-
It is one of the first studies from a multidis- to Ljøgottjern’s deepest section, where lake tegically prioritized the best land close to the
ciplinary project called Volcanic Eruptions community for crops. During warmer periods
and their Impacts on Climate, Environment, when harvests were more robust, animals
and Viking Society in 500–1250 CE (VIKINGS). were relocated to areas less suitable for crops,
“Our findings demonstrate that climate perhaps land that was still forested.
already changed in the past, it is not some- “Later, during the Viking Age and Middle
thing new, and societies had to adapt to it Ages, both activities were occurring at the
already 1,500 years ago. This shows that we same time, but it was much warmer then,
also have to adapt to the rapid climate change so the cultivation area could have been
extended,” Bajard said.
To build a more complete picture of how
farming practices evolved, Bajard’s team will
try to collect more DNA samples from near
“Over generations, hard- the lake to start quantifying how the mix of
won experience taught a animal types varied over time.
Mud cores from Lake Ljøgottjern contain sediments Peter Hambro Mikkelsen, an environmen-
farmer what works and dating back to the last glacial retreat. Credit: tal archaeologist at Aarhus University in Den-
[that] experiments could be VIKINGS project/University of Oslo mark not involved in the VIKINGS research,
said that food producers today might learn
fatal.” from this community’s ability to diversify.
“Over generations, hard-won experience
bed sediments are least affected by lateral taught a farmer what works and [that] exper-
flows. By lowering a weighted tube, they iments could be fatal. As opposed to modern
retrieved a 6-meter sediment core. Muds farming where specialization is the key to
we observe today in order to maintain and have been accumulating at Lake Ljøgottjern large-scale production, traditional agricul-
improve our food production,” said Manon since the last glacial retreat more than ture knows that when weather fails, livestock
Bajard of the University of Oslo, who pre- 10,000 years ago, so the sediments contain can perish—and the enemy can be at the
sented the research in April at the European clues about the area’s history. gates of one’s village.”
Geosciences Union General Assembly 2021. To analyze the core, Bajard’s group used
Bajard’s team analyzed sediments from carbon-14 dating to identify the section cor-
Lake Ljøgottjern in southeastern Norway. responding to 300–800 CE. Past temperature
Lake Ljøgottjern is located next to Rakni’s fluctuations were reconstructed from calcium By James Dacey (@JamesDacey), Science
mound, one of the largest barrows in north- deposits: During warmer periods, there was Writer
14 Eos // SEPTEMBER 2021You can also read
