REVEALING EARTHʼS SECRETS UNDER PRESSURE - Evolving Team Science A Nearby Black Hole Adapting Geo Skills for Virus Tracking - Eos.org
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VOL. 101 | NO. 7
JULY 2020
REVEALING
EARTHʼS SECRETS
UNDER PRESSURE
Evolving Team Science
A Nearby Black Hole
Adapting Geo Skills
for Virus Tracking
FROM THE EDITOR
Editor in Chief
Heather Goss, AGU, Washington, D.C., USA; Eos_EIC@agu.org
A Dive into the Deep Earth AGU Staff
Vice President, Communications, Amy Storey
Marketing,and Media Relations
A
round 50 years ago, scientists interested in the com- Editorial
Manager, News and Features Editor Caryl-Sue Micalizio
position, mineralogy beneath the Earth’s surface and
Science Editor Timothy Oleson
other related questions were spread throughout many News and Features Writer Kimberly M. S. Cartier
disciplines: tectonophysics, petrology, and geomagnetism, News and Features Writer Jenessa Duncombe
among others. When they began organizing their research
Production & Design
under a new name—mineral physics—“it became evident that
Manager, Production and Operations Faith A. Ishii
new scientific advances would provide dramatic progress in Senior Production Specialist Melissa A. Tribur
our understanding of Earth’s interior,” writes Robert Cooper Production and Analytics Specialist Anaise Aristide
Assistant Director, Design & Branding Beth Bagley
Liebermann in his retrospective of AGU’s Mineral and Rock
Senior Graphic Designer Valerie Friedman
Physics section on p. 24. Graphic Designer J. Henry Pereira
Our July issue, which looks at those scientific advances
Marketing
that came from developments in high-pressure and high-
Director, Marketing, Branding & Advertising Jessica Latterman
temperature experimentation, is guided by insight from Assistant Director, Marketing & Advertising Liz Zipse
Sébastien Merkel, Eos science adviser and president-elect of the Mineral and Rock Physics
section. (We also extend our appreciation to section president Wenlu Zhu for additional sup- Advertising
port.) Now a professor at the Université de Lille in France, Merkel studied physics in under- Display Advertising Dan Nicholas
dnicholas@wiley.com
graduate school and realized that he could bring a new viewpoint to the research going on in Recruitment Advertising Kristin McCarthy
the geology department. “I thought that re-creating planetary interiors in the lab was a fun kmccarthy@wiley.com
thing,” Merkel told me. And you can’t beat the tech: “We run experiments in large-scale facil- Science Advisers
ities with synchrotrons and high-power lasers. I like being in contact with and learning how Geomagnetism, Paleomagnetism, Julie Bowles
to master those beasts.” and Electromagnetism
That powerful equipment is being harnessed to explain the “new core paradox” (“Earth’s Space Physics and Aeronomy Christina M. S. Cohen
Cryosphere Ellyn Enderlin
Core Is in the Hot Seat,” p. 36). Researchers had largely assumed that the inner core was about Study of the Earth’s Deep Interior Edward J. Garnero
as old as Earth itself until an explosive 2013 paper on high-temperature experiments suggested Geodesy Brian C. Gunter
that it was rapidly cooling—and very young, perhaps a billion years old or less. Diamond anvil History of Geophysics Kristine C. Harper
Planetary Sciences Sarah M. Hörst
cells were brought in to the field, producing new papers and a conversation on errors. “This Natural Hazards Michelle Hummel
is exciting stuff,” University of Santa Cruz’s Quentin Williams told Eos for the article. These Volcanology, Geochemistry, and Petrology Emily R. Johnson
questions “will pose a challenge for the next 15 years for the community.” Societal Impacts and Policy Sciences Christine Kirchhoff
Seismology Keith D. Koper
Earth isn’t the only planet whose insides we’d like to peer into. “The experiments for study- Tectonophysics Jian Lin
ing the interiors of other planets are very new,” said Merkel. “When I was a student, we could Near-Surface Geophysics Juan Lorenzo
not even dream of measuring anything at those conditions.” In “Remaking a Planet One Atom Earth and Space Science Informatics Kirk Martinez
Paleoceanography and Paleoclimatology Figen Mekik
at a Time” (p. 30), we report on scientists using mechanisms such as dynamic compression
Mineral and Rock Physics Sébastien Merkel
from high-energy optical lasers to create pressures as high as a billion atmospheres. These Ocean Sciences Jerry L. Miller
lasers, with as much power as a bolt of lightning, have shown us that liquid helium rains down Global Environmental Change Hansi Singh
Education Eric M. Riggs
on Saturn. And scientists are looking even farther away. “We can actually say something on
Hydrology Kerstin Stahl
the structure of exoplanets, thanks to lab experiments,” said Merkel. “This is amazing.” Tectonophysics Carol A. Stein
This issue features only a small look into the potential of mineral physics. The future of Atmospheric Sciences Mika Tosca
these extreme experiments may provide answers to some of our most fundamental questions: Nonlinear Geophysics Adrian Tuck
Biogeosciences Merritt Turetsky
How did Earth evolve from a ball of molten rock into a planet that supports life? How could it Hydrology Adam S. Ward
happen on other planets? What is Earth’s core made of besides iron? How much water is inside Diversity and Inclusion Lisa D. White
Earth, and how does it affect the planet’s water cycle? What are the mechanical and chemical Earth and Planetary Surface Processes Andrew C. Wilcox
Atmospheric and Space Electricity Yoav Yair
properties that make Earth, Mars, and Venus so different? GeoHealth Ben Zaitchik
The next generation will be pursuing these questions, which is why we began this issue with
words from a mentor. “Bob [Liebermann] has trained and motivated a whole generation of ©2020. AGU. All Rights Reserved. Material in this issue may be photocopied by
scientists,” said Merkel. “He was always supportive, dynamic, and community driven.” Lieb- individual scientists for research or classroom use. Permission is also granted
to use short quotes, figures, and tables for publication in scientific books and
ermann notes in his article the rise of women directing mineral physics labs and the estab- journals. For permission for any other uses, contact the AGU Publications Office.
lishment of graduate student support and early-career awards. Here at Eos, we are excited to 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.,
watch the mineral physics community continue to grow and diversify so that it can discover and at additional mailing offices. POSTMASTER: Send address changes to Member
answers to all of these planetary mysteries. 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;
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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.
Heather Goss, Editor in Chief
SCIENCE NEWS By AGu // Eos.org 1
CONTENT
18 30
24 36
Features
18 High Water on the Delta 30 Remaking a Planet
By Nicole M. Gasparini and Brendan Yuill One Atom at a Time
On the Mississippi Delta, the past is a foreign country. By Kimberly M. S. Cartier
Helium rain on Saturn? Superionic ice on Netune?
24 Reflecting on a Half Century Scientists are discovering strange properties of planets
all from their labs.
of Mineral and Rock Physics
at AGU 36 Earth’s Core Is
By Robert Cooper Liebermann in the Hot Seat
Since its emergence in the 1960s, this relatively small
By Jenessa Duncombe
field has had an outsized influence within geoscience.
Scientists are under pressure to find answers to the
“Core Paradox.”
On the Cover
Credit: volmon@tut.by/Depositphotos.com
2 Eos // july 2020
CONTENT
4 13
5 43
Columns
From the Editor Research Spotlight
1 A Dive into the Deep Earth 42 Florida Coastlines Respond to Sea Level Rise
43 Arctic Plankton Populations Vary by Season | How
News Accurate Are Our Measurements of the Sun’s Energy?
44 Tracing the Past Through Layers of Sediment
4 Routine Monitoring Weathers the Pandemic Storm
45 The Climate and Health Impacts of Gasoline
5 Venus Exploration Starts in the Lab
and Diesel Emissions | Linking Hydrology and
7 The Long-Lasting Legacy of Deep-Sea Mining Biogeochemistry in a Tropical Urban Estuary
8 Humans Migrated to Polynesia Much Earlier
Than Previously Thought
10 Geoscientists Help Map the Pandemic
Editors’ Highlights
11 Oktoberfest’s Methane Rise Is the Wurst 46 Explaining Cold and Fresh Southern Polar Ocean
12 A Plate Boundary Emerges Between India Surface Waters | How Fast Did This Ancient Martian
and Australia Delta Form?
13 The Closest Black Hole Is 1,000 Light-Years Away
Positions Available
Opinion 47 Current job openings in the Earth and space sciences
14 Building a Culture of Safety and Trust in Team Science
Postcards from the Field
49 Installing a prototypical leaf chamber for the Water,
Atmosphere, and Life Dynamics (WALD) experiment
in the tropical rain forest of Biosphere 2.
AmericanGeophysicalUnion @AGU_Eos company/american-geophysical-union AGUvideos americangeophysicalunion americangeophysicalunion
SCIENCE NEWS BY AGU // Eos.org 3
NEWS
Routine Monitoring Weathers the Pandemic Storm
all times, so the The Coast
group has imple- In Pacific Northwest waterways, buoys in
mented extreme need of maintenance have been left unat-
cleaning and social tended, and buoys ready for deployment can’t
distancing proto- go out yet, said University of Washington
cols when in the oceanographer Jan Newton. She’s the execu-
same building. tive director for a regional branch of the Inte-
Shelter-in-place grated Ocean Observing System (IOOS), which
orders haven’t af- uses various sensors to provide real-time data
fected day-to-day for things like acidification, temperature,
monitoring opera- wind speeds, and tides to private and public
tions for seismolo- entities.
gists working for Newton describes IOOS as a set of “scien-
the Pacific North- tific oceanographic observations, but with the
west Seismic Net- intention of societal benefit”—the oceano-
work (PNSN). After graphic version of the National Weather Ser-
all, earthquakes vice.
can happen any A single buoy in Washington State’s
time of day or Puget Sound, for instance, could be simul-
night, said Harold taneously providing acidification data for
Tobin, PNSN’s di- shellfish growers, temperature data for sci-
Paul Schauer runs a level survey for a 2015 streambed scour project in Seward, rector, Washing- entific models, meteorological data for nav-
Alaska, one of many U.S. Geological Survey projects that rely on regular monitor- ton’s official state igation purposes, and phytoplankton data
ing processes. Credit: USGS seismologist, and a to track the development of harmful algal
faculty member at blooms.
the University of “People do depend on these data for things
Washington. Seis- like safe navigation for making their liveli-
P
eople throughout much of the United mologists have protocols in place for when an hood,” Newton said.
States have been strongly encouraged earthquake occurs outside normal working With s helter- i n- p lace orders, IOOS
to shelter in place since mid-March to hours. Even without shelter-in-place orders, employees can’t do routine maintenance on
prevent the spread of coronavirus disease there’s always an “on-duty” seismologist their gear, some of it aging and without a
2019 (COVID-19). ready to be woken up at 2:00 a.m. to respond replacement. For instance, an ocean acidi-
But the processes that shape Earth and its to an emergency. fication buoy was supposed to deploy in
ecosystems, like the rising and falling of “One thing that came up very early was just April, but its instruments weren’t recali-
tides, the shifting of underground rock, and the fact that you can’t shut down monitoring, brated in time because the sensor industries
the blooming of algae in the ocean, have not because it’s a public safety system,” Tobin were also affected by shelter-in-place pro-
come to a halt. And these processes—some said. tocols.
of which can lead to more loss of life—require However, the pandemic has interrupted Small industries, like mom-and-pop com-
routine monitoring. the rollout of S hakeAlert, a system that will panies that take customers out fishing, “are
Routine monitoring involves collecting provide up to tens of seconds of warning going to be the ones that need to be fully
real-time data with a suite of instruments before an earthquake might occur in Oregon functional,” Newton said.
and in situ observations. Some sensors can be and Washington. (California’s ShakeAlert
left for months or years at a time, but they network went online at the end of 2019.) The The Mountains
also might fail or need maintenance. And system needs at least 100 more seismic sta- For Amanda Henderson and her colleagues at
during a time when all of us are told to stay at tions to be complete, Tobin said. That requires the Rocky Mountain Biological Laboratory,
home, when scientists are forced to delay groups of people to work together, conduct situated about 320 kilometers southwest of
fieldwork and research campaigns, what does site visits, and install equipment within close Denver, some monitoring work involves hik-
that mean for the monitors? quarters. ing or cross-country skiing into remote loca-
Amid the new era of social distancing, the tions to measure vegetation or snowmelt.
Earthquakes ShakeAlert scientists won’t be able to install And doing fieldwork during a pandemic
“Earthquakes do not stop during epidemics,” new stations. The U.S. Geological Survey had brings up a tricky conundrum.
said Lucia Margheriti, senior researcher at the planned to publicly roll out S hakeAlert this “Being alone is safest, but given the reali-
Istituto Nazionale di Geofisica e Vulcanologia fall, but with the delay in new seismic stations ties of our environment, being with another
in Rome. The Italian government issued strict and the fact that Washington’s state emer- person is ultimately more safe,” said Hen-
stay-at-home orders on 8 March, when Mar- gency team had to turn their focus to the derson, who studies snowmelt around Gun-
gheriti and her team began working remotely. spreading pandemic, ShakeAlert will have to nison County in the spring to understand how
However, a team must be on site in the lab at wait. it affects the local waterways and the Colo-
4 Eos // july 2020
NEWS
rado River. Some of her colleagues have to
cross-country ski nearly 20 kilometers to get
Venus Exploration Starts in the Lab
to their study site. In that case, they decided
to drive to the trailhead separately and main-
tain the recommended 2 meters apart while
working.
Henderson’s own snowmelt monitoring
work can be done solo, she said, so she’s com-
fortable continuing to do her own routine
monitoring.
The Weather
Matt Kelsch, a hydrometeorologist and
weather enthusiast in Boulder, Colo., is part
of the National Weather Service’s Cooperative
Observer Program, a weather observing net-
work that’s been in place since 1891. Across
the United States, thousands of volunteers
take daily weather measurements of tem-
perature and precipitation. And because
many of these stations were set up on private
property, Kelsch said the weather network
probably isn’t much affected by shelter-in-
place orders.
These weather stations are used to create
long-term climatology records for regions The inside of the Glenn Extreme Environments Rig (GEER) is 1 cubic meter in volume, or about 3 feet wide × 4 feet
across the United States. The records can be long. Credit: GEER/NASA Glenn Research Center
used by a number of groups, including scien-
tists studying climate change and insurance
companies confirming whether damage to a
I GEER is a test chamber
car was from hail, Kelsch said. n March of 1982, the Soviet spacecraft Ven-
Weather forecasts could still be affected, era 13 landed a probe on the surface of
however. These days, many commercial Venus. It sent back the first color photo- that can create V
enus-like
flights carry weather sensors, and the airline graphs from the surface of another planet, conditions to study how
industry has seen a significant drop in traffic revealing that Venus has a desolate landscape
since the novel coronavirus came to the to match its hellish atmosphere. The probe materials placed inside the
United States. For example, the United States collected and analyzed a sample of the rocky
chamber react.
saw a 73.3% decrease in air traffic in April surface, and its acoustic detector measured
2020 compared with April 2019. On 7 May, the vibrations from the wind.
World Meteorological Organization reported Venera 13 sent back some of the best data
a 75%–80% decrease in meteorological obser- we have to date about Venus’s surface. The
vations from flights. (In the Southern Hemi- probe holds the record for the longest-lived Venus surface conditions—both lowlands
sphere, the decrease is close to 90%.) Before Venus surface mission. and highlands—up through the lower atmo-
the pandemic, commercial flights provided It survived for just 127 minutes. sphere through where we expect the cloud
more than 800,000 meteorological observa- Scientists have been trying to return to layers to be, and just slightly above the cloud
tions per day. Venus’s surface since the late 1980s, this layers and the upper atmosphere.”
“Even though a decrease in this critical time with instruments that will last for days
data will likely negatively impact forecast or even months. That’s where GEER comes Building Spacecraft to Last
model skill, it does not necessarily translate in. Venera 13, its twin spacecraft Venera 14, and
into a reduction in forecast accuracy, since GEER, the Glenn Extreme Environments the eight other successful attempts to land a
National Weather Service meteorologists use Rig at NASA Glenn Research Center (GRC) in probe on Venus all fell prey to the same thing:
an entire suite of observations and guidance Cleveland, Ohio, is a test chamber that can temperatures hotter than 450°C, pressures
to produce an actual forecast,” said National create V enus-like conditions to study how about 90 times that of Earth’s surface (90 bars),
Oceanic and Atmospheric Administration materials placed inside the chamber react. and a corrosive carbon dioxide–dominated
spokesperson Susan Buchanan in a statement “GEER is a highly adaptable facility that’s atmosphere. Under those conditions, a
released 24 March. constantly evolving its capabilities,” said spacecraft that might survive for years on
Kyle Phillips, an aerospace and mechanical Mars or the Moon would break down in min-
engineer at GRC. Phillips is GEER’s primary utes on Venus as the outer casing melts or
By JoAnna Wendel (@JoAnnaScience), Science operator and test engineer. “In past tests, dissolves, wires corrode, and delicate hard-
Writer we’ve simulated conditions all the way from ware warps.
SCIENCE NEWS BY AGU // Eos.org 5
NEWS
The GEER team has “tested things like use test results as benchmarks to interpret
basic materials that one might use in a those measurements.
spacecraft or around the spacecraft,” said The 80-day test also underscored the need
Tibor Kremic, chief of space science projects for a second, smaller test vessel that could be
at GRC. “How do those interact with the run at the same time as the larger one. “It’s a
environment? How do they fare? How did very small, mini GEER,” Kremic said. The
their properties and their functions change aptly named MiniGEER went into operation
over time in a Venus surface–like environ- in 2019. It’s just 4 liters in volume (250 times
ment?” smaller than GEER) and can be brought up to
Test material is placed inside the 1-cubic- temperature, pressure, and gas composition,
meter, corrosion-resistant stainless-steel and back down again, much faster than its
cylinder. The test engineers then ramp up the larger counterpart.
pressure, temperature, and gas composition “Maybe we have two things going on or we
inside the chamber and hold it steady for have tests that don’t require the volume [of
days, weeks, or even months. “Currently, GEER],” Kremic said, “and this way [they] can
GEER can replicate temperatures from near be done quicker and at lower cost.”
ambient up to 1,000° Fahrenheit—that’s
537°C,” Phillips said, “and it can replicate Some types of metal wiring react at Venus-like sur- The Future of Venus Exploration
pressures from ambient to rough vacuum face conditions, causing electronics to break down. NASA might be headed back to Venus in the
to…94 bars.” Shown here is a metal wire before (top) and after near future—two of its four finalists for a
“We have done work over time in under- (bottom) a test in the GEER chamber. Credit: GEER/ Discovery-class mission are bound for Venus.
standing what materials would be viable for NASA Glenn Research Center If one of those missions is selected, the GEER
long-term missions and which are not,” said facility will be involved with getting the tech-
Gary Hunter, a senior electronics engineer nology mission-ready.
with GEER. For example, “copper, you might But the team has already been hard at work
think, is just fine to use for electrical conduc- designing its own Venus mission, a small
tors. Turns out, don’t use copper. In fact, gold might be on the Venus surface,” Kremic said, probe called the Long-Lived I n-Situ Solar
would be a better material to use because the “to understand how they might change or System Explorer (LLISSE). LLISSE would
reactivity on the Venus surface and at those what they might look like if we’re trying to weigh about 10 kilograms and last at least
temperatures is different, and the materials 60 days on Venus.
that are viable are different, than you might “At Venus you get a day-to-night or night-
see in standard high-temperature operations to-day transition at least once in a 60-day
on Earth.” period,” said Kremic, who is LLISSE’s princi-
GEER has been operational since 2014, and
“Copper, you might think, pal investigator, “and so we want to make
the team has already made huge leaps for- is just fine to use for sure that we capture one of those….We’re
ward in terms of designing Venus-durable going to measure temperatures, we’re going
spacecraft. During a test a few years ago, “we
electrical conductors. Turns to measure pressures, we’ll measure winds,
demonstrated electronics operational in out, don’t use copper. In maybe 3D winds on the surface of Venus,” as
Venus surface condition for 21 days,” Hunter well as atmospheric composition and how all
said. Computer chips turned out to be fairly fact, gold would be a better of those properties change over time. The
durable. “The longest time anything else material.” team plans to build a full-scale ground model
had ever lasted before that point in terms of of LLISSE and test it inside GEER for the full
electronics on the surface of Venus…was 60 days by 2023.
approximately 2 hours. To go 21 days was The scientists are also exploring how GEER
showing a significant step up in what might can adapt to simulate other places in the solar
be possible [in] Venus surface exploration.” identify them remotely.” A basalt or a glass system and beyond. “The beauty and one of the
or a silicate might have a different spectrum unique things about GEER is that we can mix
To Venus and Back in 80 Days or appearance on Venus than on Earth, the up pretty much whatever chemistry we want,”
In its longest test to date, the GEER team sub- Moon, or Mars. Kremic said, and new hardware might let GEER
jected common geologic samples to a simu- Tests that reveal the properties of plane- reach colder-than-ambient temperatures too.
lation of Venus’s harsh surface conditions for tary materials at extreme conditions serve a “The results of what we’re doing will
80 continuous days. dual purpose, Kremic explained. Mission sci- change and enhance our ability to do science,
“We tested geologic material, so glasses, entists can tailor their instruments to mea- our understanding of our solar system, and of
basalts, minerals, things that we expect sure Venus-relevant signatures, and they can other [planetary] bodies, Venus in particu-
lar,” Kremic said, and we can “be more con-
fident in what we send there.”
u Read the latest news at Eos.org
By Kimberly M. S. Cartier (@AstroKimCartier),
Staff Writer
6 Eos // july 2020
NEWS
The Long-Lasting Legacy of Deep-Sea Mining
The impact of disturbing the seafloor for mining activities remains decades after the initial disturbance. Credit: ROV-Team/GEOMAR
M
ining for rare metals can involve a Since the start of DISCOL, scientists have Alfred Wegener Institute. (The researchers
good amount of detective work. It been visiting the basin to monitor the effects responded to email requests from Eos as a
can take time and skill to find the of mining on benthic life. In a new study in group and will be referred to as “the team.”)
most abundant sources. But in the deep Science Advances, researchers focused on the
ocean, metallic deposits sit atop the seafloor smaller communities of organisms found at Monitoring Microorganisms
in full view—a tantalizing sight for those depth (bit.ly/mining-effects). At the DISCOL site, the team deployed their
interested in harvesting polymetallic nod- “We tried to answer how long a disturbance cameras and sampling equipment and got
ules. of the deep-sea floor ecosystem by simulated their first look at the seafloor. “First, we saw
Scooping up nodules requires mechanical nodule mining could affect benthic microor- undisturbed seafloor covered by manganese
skimming of the ocean floor, which disrupts ganisms and their role in the ecosystem,” said nodules and larger animals, such as octo-
the upper centimeters of sediment. This dis- two of the paper’s authors, Tobias Vonnahme, puses, fish, and colorful sea cucumbers,”
turbance has rippling effects on sea life, but a marine biologist at the Arctic University of they said. But the troughs soon came into
the severity and duration of ecological Norway, and Antje Boetius, director of the view—even 26 years after the DISCOL exper-
impact have remained largely unknown. iment, the plough tracks were pronounced.
In a new study, researchers dove deep to The researchers took sediment cores of the
look at mining’s impact on microbial com- seafloor both within older disturbed area and
munities. They found that decades later, ben- in fresh, 5
-day-old tracks. “Thanks to novel
thic microorganisms hadn’t recovered, and robotic technologies, we were able to quantify
researchers estimated it would take at least the long-lasting impacts on microbial diver-
50 years for some ecosystem functions to sity and function in relation to seafloor integ-
return to predisturbed conditions. rity,” they noted.
After analyzing the cores from the seafloor,
Disturbing the Peace the team found that in the 2 6-year-old tracks,
In 1989, scientists began a deep-sea mining microbial activity was reduced fourfold. In
experiment called the Disturbance and Recol- addition, the mass of microorganisms was
onization experiment (DISCOL) in the Peru reduced by about 30% in the top 1 centimeter
Basin of the South Pacific Ocean. The study Brisingid sea stars like this one were among the of disturbed sediment. In fresh tracks, the
simulated nodule mining by dragging a megafauna studied by earlier evaluations at the microbes were reduced by about half. They also
plough-harrow device over an 11-square- DISCOL site in the Peru Basin. The current study found lower organic matter turnover, reduced
kilometer area, cutting and reworking the was the first to focus on the area’s microbial commu- nitrogen cycling, and lower microbial growth
upper 10–15 centimeters of seafloor sediments. nity. Credit: OFOS team, AWI Bremerhaven rates in disturbed areas.
SCIENCE NEWS BY AGU // Eos.org 7
NEWS
“Benthic life—including microorganisms,
which carry out essential functions such as
Humans Migrated to Polynesia
nutrient recycling—need more than 26 years
to recover from the loss of seafloor integrity,”
Much Earlier Than Previously Thought
said the team.
They added that on the basis of the micro-
bial activities they observed in the most dis-
turbed areas, it would take at least 50 years for
some functions to return. “Considering the
low sedimentation rates, [full] recovery will
take much longer,” they noted.
“The self-healing of the ecosystem is very
limited,” they concluded.
This is a novel study, said Maria Pachiadaki,
an assistant scientist at the Woods Hole
Oceanographic Institution who was not part
of the study. She added that it’s the first time
researchers have focused on deep-sea mining
impacts on the microbial community.
Pachiadaki and her colleagues previously
hypothesized that these types of “distur-
bances would also impact microbes, plus eco-
system functions, because microbes mediate In the middle of Lake Lanoto’o in Samoa floats the coring raft researchers used when extracting sediment sam-
the entire biogeochemistry of their environ- ples. Credit: David Sear, University of Southampton
ment.” She said this study confirms their
suspicions and gives a long-term record of
what happens after a mining disturbance.
T
“Life as we know it starts with microbes,” he last great migration of humans to Tracking Human Settlement
said Pachiadaki. She said one striking find- lands unknown occurred with the hab- Through Mud, Charcoal, and Feces
ing of the study was that the carbon fixation itation of East Polynesia about a mil- Lake sediments and mud can be used as
rates—or how inorganic carbon is transformed lennium ago. It’s not an easy feat finding tiny archives of both human environmental
into organic carbon—decreased substantially islands scattered in an ocean. impact and climate across the centuries, said
in disturbed sites. “In terms of the scale, risk, and magnitude David Sear, a professor of physical geography
Pachiadaki noted that another substantial of the exploration, it’s one of humanity’s at the University of Southampton in the
finding was the identity of the microorganisms momentous achievements,” said Barry United Kingdom and the lead author on the
in the benthic sediment. Specifically, the Rolett, an anthropologist at the University of new study. “We wanted to go and collect data
microbial communities were enriched with Hawai‘i at Manoa. along the route of the human colonization
nitrifiers. “It’s a group of organisms that make But the details of this accomplishment— story of the Pacific and follow that story in the
nitrogen bioavailable,” she explained. “Nitro- and what drove it—have been shrouded in mud from the lakes and bogs.”
gen is one of the essential micronutrients… mystery. Because of how remote the islands are, the
and the limiting factor of productivity.” Now a study published in the journal Pro- researchers had to bring their own inflatable
ceedings of the National Academy of Sciences boats, build their own rafts, and transport all
The Future of Deep-Sea Mining of the United States of America reports that their equipment by hand via jungle paths to
“Our work shows the potential long-term humans arrived in East Polynesia 200–300 drill and collect cores of mud from each
impact of deep-sea mining when seafloor years earlier than previously thought (bit.ly/ island’s lake. They initially collected mud
integrity is reduced,” said the team, adding humans-polynesia). cores from Lake Te Roto on Atiu, a part of the
that their research can be used to shape Their arrival in East Polynesia—a culturally Southern Cook Islands.
guidelines for deep-sea mining explorations. and linguistically distinct region spanning After collecting mud cores, Sear and his
“This is an excellent example of how scien- from the Cook Islands to Rapa Nui and colleagues stored them in aluminum tubes.
tists can guide policy makers,” said Pachia- Hawaii—coincides with a time of prolonged “You pack them into a cardboard box very
daki. drought in Tonga and Samoa, their West Poly- carefully, put ‘fragile’ on the outside, go to
“If there is pressure moving toward deep- nesia islands of origin. This drought may have the post office, pay 200 quid, and get it flown
sea mining, there needs to be an impact helped spur the dangerous excursions east- back to the U.K. under special import-export
assessment,” she said. “And it can’t be a ward. licenses, of course,” he said.
short-term process—it needs to be a long- “It’s an impressive study and an import- Back in the lab, researchers scanned the
term evaluation.” ant one,” said Rolett, who was not involved mud for multiple proxies of human activity,
in the research. “It’s unusual for Polynesia including charcoal, which is a sign of fire, and
because there hasn’t been a lot of paleoen- titanium, which indicates soil erosion;
By Sarah Derouin (@Sarah_Derouin), Science vironmental reconstruction work done in together they indicate deforestation of the
Writer this area.” trees and underbrush native to the island. But
8 Eos // july 2020NEWS
the most telltale sign of human presence they additional lake core samples taken from how climate has changed in the Pacific is cru-
looked for was something even more funda- islands in Samoa and Vanuatu, as well as pre- cial because it is “one of the big engines of the
mental: feces, specifically, fecal sterols, a viously published records of the Society global climate system,” Sear said, and there are
fatty substance found in mammalian feces. Islands of French Polynesia. They found that not many climate data from before the 1950s.
On these remote Pacific islands, there were human arrival in East Polynesia coincided with Better understanding of the region’s cli-
no mammals besides fruit bats prior to the an intense, prolonged drought—the driest mate system would not only shed light on the
arrival of humans and pigs. period in 2 millennia—which the researchers area’s past but also benefit the almost 12 mil-
“The idea of using fecal markers is really suggest helped drive people to migrate. lion people living in the region today.
innovative, and it works extremely well,” said However, other factors might have led to “These people are being squeezed by rising
Rolett. settlement in addition to or in conjunction sea levels, changes in precipitation, increas-
Together the evidence points to an incre- with drought, said Seth Quintus, an anthro- ing temperatures,” Sear said. “When you put
mental migration process with humans’ first pologist at the University of Hawai‘i at Manoa that together, they’re amongst the most vul-
arrival in East Polynesia around 900 CE, fol- who was not involved in the current study. nerable people on the planet.”
lowed by increased settlement activity over “It’s really hard to say that drought is what’s “If we can get a better understanding of both
the next 200 years. This study “fills in a really causing the movement of people.” how their ancestors changed the landscape
important part of the puzzle of human settle- As a whole, the study “teaches us a lot and the climate story that goes along with
ment,” said Melinda Allen, an archaeologist about how people in the past manage and that, it will help them manage their future,”
at the University of Auckland in New Zealand respond to different risks in their environ- Sear said. “Because, of course, one of their
and a coauthor on the study. “And a lot of ment,” he added. responses to climate change in the past was to
unconnected strands of evidence can now be get into a canoe and move somewhere else.”
pulled together as a result of these findings.” Pacific Climate Change “You can’t do that anymore,” he said.
Past and Future “That major adaptation strategy is no longer
Climate Change and Migration Sear said that there are still more climate data available to them.”
An extended regional drought in West Polyne- to analyze from the mud cores once the labs
sia may have driven humans eastward. The are back open: The records his team collected
researchers reconstructed regional paleocli- go back 10,000 years, and this study looked at By Richard J. Sima (@richardsima), Science
matic conditions of the past 2,000 years using only the most recent 2,000. Understanding Writer
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SCIENCE NEWS BY AGU // Eos.org 9NEWS
Geoscientists Help Map the Pandemic
heat waves for a new purpose: predicting
coronavirus risks.
“The Centers for Disease Control and Pre-
vention (CDC) identifies 15 sociodemographic
variables to calculate social vulnerabilities,”
said Fard, noting that the data are from the
U.S. census. He explained that these factors
can be grouped into four categories: socioeco-
nomics, household composition and disabil-
ity, minority status, and housing and trans-
portation. Each category gets a value, and the
values are averaged to represent the risk of
COVID-19 infection to the population within
a geopolitical boundary, in this case, a county.
Mapping a Pandemic
And the information is all easy to read on a
The mapping tool can help responders visualize where outbreaks are trending or where they may spike in the map. It has been highly successful for those
future. inside the state and in neighboring states as
well. Fard noted that during April there were
more than 2,200 views of the dashboard tool
each day on average.
T
he global pandemic threw a wrench rimental outcomes associated with heat The map can reveal insights into disease
into the field and lab work of most geo- waves. spreads, showing patterns and predicting
scientists. Vulnerabilities are a set of social factors virus hot spots. These data allow health pro-
But not Babak Fard. An environmental data that play important roles in how people react fessionals and government agencies to plan
scientist at the University of Nebraska Medi- to hazards, said Fard. “For example, age is a ahead—something Fard called adaptive
cal Center (UNMC) College of Public Health in very important factor in [heat waves],” he capacity. “It’s any measure that can help in
Omaha, Fard has leveraged his interdisciplin- noted, adding that different studies show that reducing the vulnerability,” he said, and can
ary background to track and predict corona- nonwhite and minority groups are more vul- include anything from increasing the number
virus disease 2019 (COVID-19) infection risks nerable as well. of beds in intensive care units to addressing
to Nebraskans. The team used data on vulnerabilities to transportation issues.
He and his colleagues created a dashboard identify populations at the highest risk using These maps might be a crucial tool for pan-
tool (bit .ly/Neb -COVID-19) that can help something called a risk framework. The more demic responders, said Kacey Ernst, an epi-
responders visualize where outbreaks are vulnerabilities a person has—age, minority demiologist and program director of epide-
trending or where they may spike in the status, reliance on public transportation—the miology at the University of Arizona who was
future. The tool is helping health care provid- higher the risk is. “One purpose of the risk not involved with the research. “We might
ers and public policy leaders get supplies and framework is to enable the decision-makers want to enhance our level of testing to catch
resources to the areas of Nebraska that need to prioritize their resources to different areas more cases [in a certain area] or put up a test-
them most. that need attention during a crisis,” said Fard, ing center if there’s an area where people
adding that with limited budgets and supplies, would have to take the bus or public transport
Geohealth at Work this information is crucial for prioritizing when they’re ill to get tested,” she said.
While a doctoral student at Northeastern responses. “I was impressed that [Fard] was looking
University in Boston, Fard mapped the risk of In his new position at UNMC, Fard used the at a multitude of underlying factors that
heat waves to residents of Brookline, Mass., bones of the risk framework his team built for might influence what the numbers would
using a framework tool. The project was part say,” said Ernst. She added that she was par-
of AGU’s Thriving Earth Exchange, in which ticularly impressed with the hospital data
scientists work on a problem that advances they included. “I appreciated the fact that he
community solutions. didn’t just put up the case numbers—that he
“We wanted to look at how these extreme
The tool is helping health was trying to delve a little more deeply.”
temperatures affect public health,” said Fard, care providers and public Ernst said it’s important to look beyond the
adding that the issue has become a global number of cases and into why the cases are
concern. The team identified the hazard (heat
policy leaders get supplies there. “It’s absolutely critical to really under-
waves) and vulnerabilities that can lead to and resources to the areas stand the underlying population and how that
adverse reactions to the hazard. Using these might influence what you see, in terms of
data, team members created a regional map
of Nebraska that need both differences in how diseases are reported
of communities with the highest risks of det- them most. and in how testing is being conducted.”
10 Eos // july 2020NEWS
It’s important to look Oktoberfest’s Methane Rise Is the Wurst
beyond the number of
M
cases and into why the illions of people convene at large fes- Oktoberfest premises. That’s significant and
tivals like Carnival in Rio de Janeiro only about a factor of 2 smaller than the flux
cases are there. and Dia de los Muertos in Mexico escaping from a dairy farm, the team noted.
City. These gatherings are more than just wild Roughly 20% of these emissions can be
parties or cultural heritage, however—they’re ascribed to biogenic methane produced by
a rich trove of scientific data. Researchers now attendees’ exhalations and flatulence, Chen
The Power of Interdisciplinary have calculated the methane emissions asso- and her colleagues calculated on the basis
Research ciated with Oktoberfest, a harvest celebra- of published estimates (b it.l y/ h uman
The project is a perfect example of how geo- tion typically held in the fall, in Munich, Ger- -emissions). The remainder, the researchers
scientists can think and apply their skills out- many. (The 2020 event has been canceled.) suggest, likely derived from incomplete com-
side the traditional bounds of their research. The scientists found that Oktoberfest’s a rea- bustion in gas-powered heaters or cooking
“As geoscientists, we know how to work with normalized methane flux was about half that appliances.
maps and do geospatial analyses,” said Fard, of an average dairy farm. Festivals—often These results were published in Atmo-
adding that medical geologists can go one unaccounted for in emissions inventories— spheric Chemistry and Physics (b i t .l y/
step further and study the effect of geological can be significant, albeit temporary, sources Oktoberfest-emissions).
factors on health. He noted that geospatial of greenhouse gases, the team concluded.
skills can add a lot of value for crisis respond-
ers who need a visual picture of where to Beer, Sausage, and Methane
focus. At Munich’s Oktoberfest, typically held “Festivals could be a
Ernst agreed and said it is imperative, over 16 days, revelers consume more than
especially during a pandemic, for scientists to 8,000,000 liters of beer and copious amounts
notable methane source
look critically at every data source and try to of grilled sausage, fish, and oxen. But the nat- even though they have
understand its limitations and caveats. ural gas used to heat Oktoberfest’s massive
“Many geoscientists do sort of broader scales, tents and power its grills consists primarily of
not yet been included
spatial scales,” she said, adding that often, methane, which is a potent greenhouse gas: in the existing emissions
geoscientists “get that blessing and curse of Kilogram for kilogram, methane traps roughly
spotty data, and you have to learn how to fig- 30 times as much energy as carbon dioxide. inventories.”
ure out what it actually means and what you Jia Chen, an electrical engineer focused on
can do with it.” environmental science at the Technical Uni-
In the increasingly connected world, versity of Munich, and her colleagues set out
interdisciplinary research like Fard’s may to quantify Oktoberfest’s methane emissions. Allowed In the Next Time
become the norm, not the exception. For “Festivals could be a notable methane source In 2019, the researchers returned to Oktober-
Ernst, this is already the case. “I am a strong even though they have not yet been included fest, this time on the actual premises. “We
proponent of interdisciplinary research in the existing emissions inventories,” said were allowed to go inside,” said Florian Diet-
teams—that’s pretty much how I do all my Chen. “Oktoberfest is the largest folk festival rich, an engineer at the Technical University
work,” she said. “It makes the research worldwide.” of Munich and a member of the team. “We
really strong when you have teams that are went closer to the sources.”
diverse and able to look at data from differ- Many Rounds for Science This time, they made measurements with
ent angles.” In 2018, Chen and her collaborators walked portable methane sensors and also collected
Fard said that the framework tool is a larger and biked around the 2.5-kilometer perime- air samples. Back in the laboratory, they
part of the Nebraska Emergency Prepared- ter of the Oktoberfest site carrying portable determined the ratio of ethane to methane in
ness and Response effort. And although it is methane sensors. The team made 94 rounds the samples to shed light on the origin of the
currently being used for COVID-19, “this with the instruments, which were about the emissions—biogenic sources produce very
framework is going to continue to be benefi- size of a backpack and weighed roughly little ethane, whereas fossil fuels (e.g., natu-
cial in other situations that might come up in 11 kilograms. “It’s good exercise,” said Chen. ral gas) typically contain ethane. The results
the future,” such as floods and other natural The sensors determined gas concentra- are being prepared for publication.
hazards. tions by pumping air into a cavity and then “There are so many different sources of
The framework provides mayors, hospitals, measuring the attenuation of different wave- methane,” said Ben Poulter, a carbon cycle
and relief workers information for planning lengths of laser light. The team combined scientist at the NASA Goddard Space Flight
and disaster response. Fard said he hopes that these data with wind information to accu- Center in Greenbelt, Md., not involved in the
seeing the success of the coronavirus frame- rately estimate methane fluxes. “The higher research. “Studies like this help individuals
work will “inspire other organizations to use the wind speed, the lower concentration we understand their greenhouse gas footprint a
it for their purposes.” will measure because the methane is more little bit better.”
diluted,” said Chen.
The researchers found that on average, about
By Sarah Derouin (@Sarah_Derouin), Science 7 micrograms of methane per second were By Katherine Kornei (@KatherineKornei),
Writer being emitted from each square meter of the Science Writer
SCIENCE NEWS BY AGU // Eos.org 11NEWS
A Plate Boundary Emerges Between India and Australia
“What we see in this region
in the middle of the ocean
is very analogous to other
plate boundary regions.”
extends.” This feature, the team surmised,
was consistent with being a plate boundary.
An important next step was to estimate its
slip rate.
Slower Than San Andreas
To do that, the scientists relied on two quan-
tities: the length of the largest, and presum-
ably oldest, pull-apart basin (roughly 5,800
meters) and the duration of the most recent
episode of fault activity (roughly 2.3 million
years). By dividing the length of the pull-
Mid-ocean ridges, like this one near Vancouver Island in Canada, reveal plate boundaries. Credit: Ocean Net- apart basin by this time interval, they calcu-
works Canada lated a maximum slip rate of about 2.5 milli-
meters per year. That’s roughly tenfold
slower than the rate along other strike-slip
plate boundaries like the San Andreas Fault
T
ectonic plates blanket the Earth like a ing under the Sunda plate, but its northern but not much slower than the slip rates of
patchwork quilt. Now researchers portion is buckling up against the Himalayas, other kinds, like the Dead Sea Fault and the
think they’ve found a new plate bound- which are acting like a backstop. Owen Fracture Zone, the team noted.
ary—a seam in that tectonic quilt—in the “There’s a velocity difference that is On the basis of that slip rate, Coudurier-
northern Indian Ocean. This discovery, made potentially increasing,” said C oudurier- Curveur and her collaborators estimated the
using bathymetric and seismic data, supports Curveur, who completed this work while at return interval for an earthquake like the
the hypothesis that the I ndia-Australia- the Earth Observatory of Singapore at Nan magnitude 8.6 one reported in April 2012.
Capricorn plate is breaking apart, the team yang Technological University. Assuming that such an event releases several
suggests. tens of meters of coseismic slip, a similar
Zooming In on Fractures earthquake might occur every 20,000 or so
Earthquakes in Unexpected Places oudurier-Curveur and her colleagues stud-
C years, said C oudurier-Curveur. “Once you
In 2012, two enormous earthquakes occurred ied one particularly fracture-riddled region of release the stress, you need a number of years
near Indonesia. But these massive tem- the I ndia-Australia-Capricorn plate near the to build that stress again.”
blors—magnitudes 8.6 and 8.2—weren’t Andaman-Sumatra subduction zone. They These results were published in Geophysical
associated with the region’s notorious used seismic reflection imaging and multi- Research Letters (bit.ly/new-plate-boundary).
Andaman-Sumatra subduction zone. Instead, beam bathymetry, which involve bouncing The findings are convincing, said Kevin
they struck within the I ndia-Australia- sound waves off sediments and measuring Kwong, a geophysicist at the University of
Capricorn plate, which made them unusual the returning signals, to look for structures at Washington in Seattle not involved in the
because most earthquakes occur at plate and below the seafloor consistent with an research. “What we see in this region in the
boundaries. active fault. middle of the ocean is very analogous to other
These earthquakes “reactivated the Along one giant crack that the team dubbed plate boundary regions.”
debate” about the India-Australia-Capricorn F6a, Coudurier-Curveur and her colleagues But continuing to monitor this part of the
plate, said Aurélie C
oudurier-Curveur, a geo- found 60 pull-apart basins, characteristic seafloor for earthquakes is also important, he
scientist at the Institute of Earth Physics of depressions that can form along strike-slip said, because temblors illustrate plate bound-
Paris. plate boundaries. The team showed that the aries. That work will require new instrumen-
Some scientists have proposed that this basins followed a long, linear track that tation, said Kwong. “We don’t have the seis-
plate, which underlies most of the Indian passed near the epicenters of both of the 2012 mic stations nearby.”
Ocean, is breaking apart. That’s not a wholly earthquakes.
unexpected phenomenon, because the plate “It’s at least 1,000 kilometers,” said
is being tugged in multiple directions, said Coudurier-Curveur. “It might be even longer, By Katherine Kornei (@KatherineKornei),
Coudurier-Curveur. Its eastern extent is slid- but we don’t have the data to show where it Science Writer
12 Eos // july 2020NEWS
The Closest Black Hole Is 1,000 Light-Years Away
S “We thought it was only
upermassive black holes—millions or around,” said Rivinius. That’s the telltale
even billions of times more massive sign of a companion, a nearby object that’s
than the Sun—anchor the centers of tugging gravitationally on the observed two stars.”
most galaxies. But smaller black holes, at
just a few solar masses, should theoretically
pepper galaxies in droves. A few hundred
candidates have been found in the Milky A team member died in a car accident in
Way. Now researchers have spotted another June 2014. “The study stalled,” said Rivinius.
one of these stellar mass black holes, and it But last year, new results spurred Rivinius
holds a special honor: It’s the closest black and his colleagues to revisit their findings.
hole to Earth yet discovered. The findings Another team of researchers had reported
shed light on the dynamics of super- finding a black hole using the same
nova explosions that go on to create method. Rivinius remembered seeing a
black holes, the team suggested. press release and thinking, “Wait a
second—I have something in the
Finding Wallflowers drawer that looks exactly the same.”
Disks of hot gas and dust glowing
brightly in X
-rays sometimes encircle The Closest One
black holes. This radiation indicates Rivinius and his collaborators esti-
that a black hole is active and accret- mated that the black hole in HR 6819
ing matter, said Thomas Rivinius, an was about 1,000 light-years from Earth,
astronomer at the European Southern making it the closest known black hole.
Observatory in Santiago, Chile. And it’s a Its proximity implies that systems like this
beacon. “We only find the [black holes] that one are common. “Our neighborhood is
are violently gobbling up material from their nothing special,” said Rivinius. “If it’s here,
environment,” said Rivinius. it must be everywhere.”
It’s much harder to spot the many black These results were published in Astron-
holes that aren’t consuming matter—they omy and Astrophysics (bit.ly/nearest-black
don’t produce X -rays. But sometimes the -hole).
universe aligns itself just right to reveal Astronomers found the closest black hole to the Sun The existence of HR 6819 sheds light on the
these wallflower black holes. That’s what in the constellation Telescopium. Credit: ESO/ supernova explosions that create black holes,
Rivinius and his collaborators found when Digitized Sky Survey 2; Acknowledgment: Davide the scientists suggested. It’s long been
they examined HR 6819, a seemingly ordi- De Martin believed that such explosions are antisym-
nary pair of stars about 1,000 light-years metric, meaning that they send matter flying
away in the constellation Telescopium. preferentially in one direction, with the result
that the black hole is launched in the other
celestial object. So HR 6819 wasn’t just a pair direction. But finding a black hole gravita-
of stars—it was three objects: one star on a tionally bound to a star implies that in some
relatively wide orbit and one star paired with cases, black holes aren’t flung from their
“There are probably a something unseen. birthplace. That is, supernova explosions are
million black holes in the sometimes symmetric.
Not a Star, White Dwarf, Determining what fraction of supernovas
galaxy that have binary or Neutron Star are symmetric versus antisymmetric will
companions that are The scientists calculated that the mysterious require a larger sample of black holes.
third object in HR 6819 had to be at least That’s entirely possible research, said Todd
stars.” about 4 times the mass of the Sun. That’s Thompson, a theoretical astrophysicist at
pretty hefty—a star of that mass would the Ohio State University in Columbus not
pump out enough light to be visible even if involved in the research. “There are prob-
it belonged to the dimmest class of stars, ably a million black holes in the galaxy that
Rivinius and his collaborators estimated. have binary companions that are stars,”
In 2004, Rivinius and his colleagues They also ruled out fainter objects like white said Thompson. “That’s a very big sample
trained a 2.2-meter telescope in La Silla, dwarfs and neutron stars because they’re that we should get busy trying to under-
Chile, on HR 6819. “We thought it was only typically of much lower mass. That left one stand.”
two stars,” said Rivinius. logical conclusion: The unseen object was a
But to their surprise, the researchers dis- black hole.
covered that one of the stars was wobbling That idea languished for several years, By Katherine Kornei (@KatherineKornei),
in a circle. “One of them was being flung however, after tragedy struck unexpectedly: Science Writer
SCIENCE NEWS BY AGU // Eos.org 13You can also read
