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VOL.
VOL.103 | NO.
104 | NO.101
OCTOBER
JANUARY 20222023
THE SCIENCE OF
RESILIENT FORESTS
Researchers develop tools and techniques
to monitor and preserve woodland health.
MESSENGER Reveals
a Mercurial Mercury
An Inclusive Approach
to Oceangoing Research
Supercontinents
and Mantle Structures
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FROM THE EDITOR
Editor in Chief
Caryl-Sue Micalizio, Eos_EIC@agu.org
A Forest, for the Trees
Editorial
Managing Editor Jennifer Schmidt
Senior Science Editor Timothy Oleson
Associate Editor Jason P. Dinh
T
Senior Science Reporter Kimberly M. S. Cartier
his month, Eos takes a walk in the woods to explore how News and Features Writer Jenessa Duncombe
forests are faring and what strategies are helping to
strengthen our approaches to fire ecology. Production & Design
In “For Western Wildfires, the Immediate Past Is Prologue,” Assistant Director, Operations Faith A. Ishii
Senior Production and Analytics Specialist Anaise Aristide
Ronnie Abolafia-Rosenzweig, Cenlin He, and Fei Chen strike Assistant Director, Design & Branding Beth Bagley
an appropriately Shakespearean chord when noting that “the Program Manager, Brand Production Valerie Friedman
Senior Graphic Designer J. Henry Pereira
tight coupling between climate and fire in the western United
Multimedia Graphic Designer Mary Heinrichs
States has been enhanced by the legacy of fire suppression and Graphic Design Intern Symphony Campbell
a lack of prescribed burning” (p. 28). Throughout this issue,
scientists, historians, and policymakers echo this scrutiny of Strategic Communications and Marketing
Vice President Joshua Weinberg
the long legacy of fire suppression in the U.S. West. They also Publisher Heather Goss
work to address it: In this article, authors use burgeoning pos- Assistant Director, Marketing & Advertising Liz Zipse
sibilities offered by satellite observation and machine learning Senior Marketing Specialist Camila Rico
to uncover the extent of burned areas and produce more accurate forecasts of summer fire
Advertising
activity.
Display Advertising Steve West
Scientists studying refugia—those elusive patches of forest that evade incineration—are steve@mediawestinc.com
similarly researching ecosystems made unpredictable by human activity and climate change. Recruitment Advertising recruitmentsales@wiley.com
“Last Tree Standing” by Robin Donovan documents how scientists analyze the seemingly arbi- Science Advisers
trary distribution of forest refugia and use tools ranging from s eed-dispersal databases to Tra- Geodesy Surendra Adhikari
ditional Knowledge frameworks to predict and preserve them (p. 22). Hydrology José Luis Arumi
Finally, by taking “A Lidar’s-Eye View of How Forests Are Faring,” scientists use a familiar Ocean Sciences Clark Alexander
Natural Hazards Paula R. Buchanan
and flexible technology to reveal a holistic portrait of forested landscapes (p. 34). Van R. Kane, GeoHealth Helena Chapman
Liz Van Wagtendonk, and Andrew Brenner provide dazzling lidar images of Yosemite National Atmospheric and Space Electricity Kenneth L. Cummins
Tectonophysics Rebecca Dorsey
Park while detailing how such data are not limited to fire management applications.
Education Kyle Fredrick
In addition to these deep dives out West, this month offers introductions to Free-Air CO2 Diversity and Inclusion Sapóoq’is Wíit’as Ciarra Greene
Enrichment technology in the Amazon (p. 4) and the Internet of Things in Germany’s Black Space Physics and Aeronomy Jingnan Guo
Hydrology Caitlyn Hall
Forest (p. 18). We hope this issue of Eos offers you some practical hope by way of solutions- Science and Society Sara Hughes
oriented approaches to wildfire ecology. Planetary Sciences James T. Keane
Cryosphere Michalea King
Seismology Ved Lekic
Mineral and Rock Physics Jie “Jackie” Li
Near-Surface Geophysics Juan Lorenzo
Volcanology, Geochemistry, and Petrology Michelle Jean Muth
Atmospheric Sciences Vaishali Naik
Study of the Earth’s Deep Interior Rita Parai
Caryl-Sue Micalizio, Editor in Chief Earth and Space Science Informatics Sudhir Raj Shrestha
Global Environmental Change Hansi Singh
Geomagnetism, Paleomagnetism,
and Electromagnetism Nick Swanson-Hysell
Nonlinear Geophysics Daniele Telloni
Paleoceanography and Paleoclimatology Kaustubh Thirumalai
Earth and Planetary Surface Processes Desiree Tullos
Biogeosciences Merritt Turetsky
History of Geophysics Roger Turner
Global Environmental Change Yangyang Xu
©2023. 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.
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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.
Randy Fiser, Executive Director/CEO
SCIENCE NEWS BY AGU // Eos.org 1
CONTENT
28
22 34
Features
22 Last Tree Standing 28 For Western Wildfires, the
By Robin Donovan Immediate Past Is Prologue
Once long-standing “oases of the woods,” forest By Ronnie Abolafia-Rosenzweig et al.
refugia are being redefined by climate change.
Can winter and spring weather in the U.S. West predict
the severity of the following summer wildfire season?
Let’s use AI to find out.
On the Cover
A fire encroaches on a forest near Cherskiy, Russia, in 2020.
Credit: Nikita Zimov 34 A Lidar’s-Eye View of How
Forests Are Faring
By Van R. Kane et al.
The 3D scanning technology is a vital tool for
illuminating forest structure and improving
woodlands’ resilience to fires.
2 Eos // JANUARY 2023
CONTENT
4 19
11 40
Columns
From the Editor Research Spotlight
1 A Forest, for the Trees 40 Food Deficits in Africa Will Grow in a Warmer World
41 Melting Below the Pine Island Ice Shelf Minds the Gap
News 42 Fiber Optics Opens New Frontier for Landslide
Monitoring | Deep Earthquakes Suggest
4 Testing the Resilience of the Amazon
Well-Hydrated Mariana Subduction Zone
5 An Inclusive Approach to Oceangoing Research
43 Amazon Basin Tree Rings Hold a Record of
7 Reaching New Levels in Groundwater Monitoring the Region’s Rainfall
8 Not Your Childhood Water Cycle 44 Spatial Scale Shapes How Ocean and Atmosphere
10 Indian Cities Invest in Low-Cost Air Quality Sensors Influence Climate | Higher Lead Concentrations
11 Long-Gone Moon Could Explain Birth of Found in Diseased Bones
Saturn’s Rings
13 Neighborhood Strategies Inform Boston’s First Urban
Forest Plan
Editors’ Highlights
14 Seafloor Reveals a Period of Rapid Retreat for 45 Convection May Explain Ceres’s Missing Craters
Thwaites Glacier and Strange Crust | The Burning Problem for Natural
16 Billion-Year Rewind Tracks Supercontinents Climate Solutions
and Mantle Structures
18 Scientists Bring Forests into the Internet of Things Positions Available
46 Current job openings in the Earth and space sciences
Opinion
19 Tackling Challenges of a Drier, Hotter, More Postcards from the Field
Fire-Prone Future
48 Hello from Putre, Chile!
AmericanGeophysicalUnion @AGU_Eos company/american-geophysical-union AGUvideos americangeophysicalunion americangeophysicalunion
SCIENCE NEWS BY AGU // Eos.org 3
NEWS
Testing the Resilience of the Amazon
H
ang on to your seats: An international equivalent of the carbon footprint of a single transform it into sugars that may add to their
project is preparing to intentionally round-trip flight from New York to São Paulo, biomass. Some researchers have hypothe-
release carbon dioxide (CO 2 ) into said scientists. The amount of CO2 emitted by sized that great amounts of CO2 would there-
patches of the Amazon rain forest to under- the towers will be offset through reforesta- fore “fertilize” forests, allowing them to
stand how such ecosystems will respond to tion, largely in the region outside Manaus. continue to absorb carbon and slow climate
climate change. It may sound counterproduc- “This is a fundamental experiment,” said change—and that is what research using
tive, but the experiment will help answer an Jerry Melillo, a biologist at the Marine Biolog- FACE in nontropical forests has suggested
elusive question: Will the biggest tropical ical Laboratory at the University of Chicago so far.
forest in the world continue to soak up carbon who is not involved with the initiative but But critics have argued that this process
from the atmosphere as temperatures con- tried to raise funding to conduct a similar might not apply to tropical forests because
tinue to rise? experiment in the Amazon 2 decades ago. they have soils poor in nutrients, which would
With more than 20 years of planning and “The tropics have been a big question limit plant growth at some point. In a warm-
some $5 million in funding from science mark,” he explained, in understanding for- ing climate, tropical forests could start
agencies in Brazil and the United Kingdom, ests’ carbon sink capacity in a high-emissions releasing more CO2 through respiration than
AmazonFACE (Free-Air CO2 Enrichment) will future. Today forests sequester about a quar- they absorb through photosynthesis, making
use 3
5-meter-high metal towers to inject CO2 ter of all CO2 emitted by humans. them carbon sources instead of carbon sinks
into the tree canopy at a forest research sta- and further accelerating climate change.
tion in Manaus, Brazil. Scientists have con- Carbon Sink or Carbon Source
ducted similar experiments using FACE tech- For more than 30 years, scientists have dis-
nology in forests in Australia, Italy, and the cussed what will happen to forests as CO2 in
United States, but this is the first time FACE the atmosphere continues to rise.
will be deployed in a tropical environment. In theory, plants grow faster when exposed
“This will be the most
The annual amount of CO2 to be injected to increased amounts of the gas: Trees take up precious carbon ever
into each plot (about 1,200 metric tons) is the CO2 from the air through photosynthesis and
emitted in the Amazon.
It will help us understand
and preserve the forest.”
“We currently don’t know how long this
fertilization effect can be sustained or if it is
even real,” said David Lapola, leader of the
AmazonFACE project and an ecologist at the
University of Campinas in Brazil. Lapola
pointed out that under a c arbon-saturated
environment with extreme climate change,
the Amazon could become a dry and hot
savanna. “That [situation] would bring cata-
strophic changes that would alter the climate
on a continental scale,” he added.
Recent studies have suggested that the
Amazon has already lost more than 30% of its
ability to soak up carbon since 1990. Lapola
said it is not possible to know yet whether this
is due to changes in climate. The new exper-
iment will help answer this and other ques-
tions.
Pumping Gas into the Forest
The AmazonFACE project has a long history.
The original idea was proposed in the 1990s,
and work on the current iteration began in
2011. But lack of funding and logistical chal-
The AmazonFACE project, as shown in this artist’s illustration, will involve a series of 3
5-meter-high metal towers lenges got in the way. “Can you imagine pro-
injecting CO2 into the tree canopy. Credit: P. Lorenzo & R. Lupo/AmazonFACE ducing all these giant towers and bringing
4 Eos // JANUARY 2023
NEWS
An Inclusive Approach
to Oceangoing Research
T
he research ship leaving the port of ages in early 2021. Despite the organization’s
Rimouski in August 2022 appeared to best efforts, the sea expeditions had low
be embarking from the St. Lawrence diversity, equity, and inclusion of women,
River on yet another science expedition. racialized minorities, Indigenous Peoples,
A researcher ascends an observation tower in a plot But this voyage was anything but ordinary. people with disabilities, and people identify-
near Manaus, Brazil, where the A mazonFACE exper- The people on board included artists, social ing as LGBTQIA2S+. Trips lacked a variety of
iment will be carried out. Credit: João M. Rosa/ scientists, members of a nearby Indigenous fields of study, too.
AmazonFACE community, and (a few) scientists. Many
identify as part of groups that have tradition-
ally been minoritized in the marine sciences.
And most had never done anything like this For one attendee, early
a giant crane into the dense forest?” asked before.
Lapola. Led by Réseau Québec Maritime (RQM), an feelings of imposter
AmazonFACE will involve a series of towers
arranged in six 30-meter-diameter rings in
oceanographic network hosted by the Univer-
sity of Quebec at Rimouski, the Inclusion Mis-
syndrome on the cruise
the rain forest. Each ring will contain 16 indi- sion would take the group northeast along transformed into feelings
vidual towers. Two plots are currently under
construction, and the remaining will be ready
the secluded north shore of the St. Lawrence
River and Gulf of St. Lawrence. In the days to
of belonging.
by late 2023, when the experiment starts run- come, they’d not only trap sediment, trawl for
ning.) Half of the rings will pump out 50% ocean life, and record the water’s physical and
more CO 2 than is currently in the atmo- chemical characteristics but also make art
sphere; the rest will serve as controls and and meet with Indigenous communities. Many minoritized groups face barriers
spray only regular air. Although the trip constituted only one of to participating in research cruises. Fewer
Sensors in the towers will record the tem- many research cruises worldwide, it built on than 30% of U.S. oceanographic expeditions
perature and the concentration of water vapor movements to decolonize science and make between 2000 and 2014 had female chief sci-
and CO2 in the air. Monitoring will go on for discovery accessible to all. entists, according to one study. A quarter of
the 10 years that CO2 will be emitted from the For one of the Inclusion Mission’s attend- Canadians have a disability, but some geosci-
towers, during which time researchers will ees, postdoctoral scholar Annie Tamalavage, entists have said the field sends a message
also measure characteristics of the forest early feelings of imposter syndrome on the that they aren’t welcome. LGBTQIA2S+ sci-
including leaf and root growth; the amount of cruise transformed into feelings of belonging entists reported in a global survey that they
carbon in the plants, soil, and air; soil nutri- by the trip’s end. “It was like a very, very pro- are less open about their identities in the
ents; the rate of photosynthesis; and water found experience,” she said. Earth sciences than in other disciplines. And
flux. These measurements will help research- of the 6,720 graduate students in geosciences,
ers better understand how the trees use car- A Seat at the Table atmospheric sciences, and ocean sciences in
bon, and results will be shared with local The goal of the Inclusion Mission, said trip the United States in 2018, only 860 (about
communities and policymakers. leader Maxence St-Onge, was to break down 13%) were people of color.
“The big question is, Where will the carbon barriers to seagoing research. Calls to decolonize science have extended
go?” asked Richard Norby, an ecosystem A marine geologist by training, St-Onge to oceangoing research, too. In 2019, the
ecologist at Oak Ridge National Laboratory conducted a diversity analysis of RQM voy- Canadian Indigenous Delegation summoned
who is involved with AmazonFACE. If the
additional carbon does not increase wood
growth, for example, it may increase the
growth of leaves and roots, which can quickly
return the gas to the atmosphere. “Even if
there is no tree growth, there almost certainly
will be some important responses that will
improve our understanding of how the eco-
system will react.”
“This will be the most precious carbon ever
emitted in the Amazon,” said Lapola. “It will
help us understand and preserve the forest.”
By Sofia Moutinho (@sof iamoutinhoBR), Inclusion Mission participants worked together to create an art project inspired by oceanographic rosettes.
Science Writer Credit: Michel Castilloux
SCIENCE NEWS BY AGU // Eos.org 5
NEWS
the ocean-observing community to recognize the emotional landscape of the voyage and
the Traditional Knowledge of Indigenous the personalities of the people on it.
Peoples worldwide. The Aha Honua declara- “The results also show how open or truth-
tion rallied scientists to create “meaningful ful a person can be in examining how they
partnerships” with Indigenous groups and are feeling,” Robitaille said.
nations.
To target these issues specifically, St-Onge Annie Tamalavage: Rekindling Passion
prioritized applicants from minoritized For paleoclimatologist Tamalavage, the
groups or people from nontraditional research Inclusion Mission signaled a return to sea
disciplines for spots on the cruise. And all voyages driven by curiosity, not just analyt-
participants took training from the Quebec- ical research.
based, Indigenous-led training group Ashu- Modern natural science has its roots in
kan on best practices for research with Indig- early scientific voyages by Europeans seek-
enous communities. ing knowledge and wealth on distant shores.
In the end, a little over a dozen people par- Charles Darwin penned detailed accounts of
ticipated in the cruise, and each came with a his observations as a naturalist on board
unique story: An Innu intern had promised HMS Beagle from 1831 to 1836. Just decades
himself he’d try something new this year. An later, mariners on HMS Challenger laid the
architect-turned-artist had regretted never foundation of oceanography by sailing the
having studied oceanography. And an early- Doctoral student Pauline Bertrand (left) and Réseau world from 1873 to 1876, taking measure-
career paleoclimatologist questioned her Québec Maritime scientific missions coordinator ments of temperature, chemistry, and cur-
future in academia. Maude Boissonneault show off the sea’s bounty. rents.
Credit: Maxence St-Onge “Although we know early exploration has
many conflicts related to colonialism and
conquest, I have spent time trying to relate
“I was just so hopeful and myself to these men from a scientific per-
During the voyage, Lavoie and others vis- spective,” said Tamalavage, whose research
reminded [of] why I love ited villages that could be reached only by project for the Inclusion Mission studied car-
this work in the first place.” boat or plane. Western science disciplines
often choose research methods before start-
bon transported through the mouth of the
Romaine River over time as human indus-
ing a project, but Lavoie is cocreating the tries morphed along its shores.
research design with her Indigenous part- Deep philosophical pondering about our
ners. planet and a desire to explore were goals that
William St-Onge: The Richness connected the Inclusion Mission with his-
of the Sea Danielle Robitaille: A Place for Art torical journeys, said Tamalavage. The con-
William St-Onge (no relation to Maxence) Artist Danielle Robitaille originally planned nection was made more potent by bringing
worked as an intern for the Territory and to study oceanography in college but chose together a diverse group.
Resources sector in his Pessamit community architecture to stay closer to family. Although “There was like a lot of emotion relative
along the St. Lawrence River’s north shore. excited to finally go to sea, Robitaille worried to the cruise, like everyone was kind of cry-
When his supervisor told him about the about fitting in. ing at various times,” Tamalavage said.
Inclusion Mission, he immediately said yes. “I was a little afraid that art processes “When I could get on board and see and feel
He’d promised himself to try new things that could be regarded as nonvalid by scientists, respected as a woman…I was just so hopeful
year. but that was not the case at all,” Robitaille and reminded [of] why I love this work in the
On the ship, S
t-Onge dissected mollusks, said. first place.”
released trawl nets, and scooped up sediment Since 2019, Robitaille’s art has mapped her
in a Van Veen sampler. These new tasks were emotions on a daily emotion wheel. The proj- Inclusion Mission 2.0?
part of research projects proposed by scien- ect borrows from data art and procedural art Last summer, RQM also supported an
tists who’d applied for the voyage. Working because it involves continually collecting LGBTQIA2S+ and woman-led scientific sail-
hours stretched from 7:00 a.m. to 11:00 p.m. information. ing expedition studying plastics in the
“There wasn’t much I didn’t like,” said During the Inclusion Mission, her emo- St. Lawrence.
St-Onge. “Discovering all the marine life was tions ranged from overwhelmed joy to As with most research projects, said orga-
stunning. I was clueless about most of it.” energy-sapped fatigue. nizer Maxence St-Onge, funding is the main
St-Onge also aided a research initiative It wasn’t long before the onboard experi- factor that will decide whether RQM will be
involving five Indigenous communities and ence began shaping her art. She renamed able to reiterate and deepen the spirit of the
their changing relationship with the St. Law- the emotion wheel a “feelings rosette.” In Inclusion Mission in the years to come. “We
rence. The research project is led by social oceanography, a rosette sampler is an instru- really hope so.”
scientist Roxane Lavoie from Université Laval ment that measures salinity, temperature,
in Quebec and seeks to understand how and other characteristics of ocean water.
marine vessel traffic along the St. Lawrence Others on board began filling out feelings By Jenessa Duncombe (@jrdscience), Staff
River affects Indigenous communities. rosettes, too. Side by side, the rosettes revealed Writer
6 Eos // JANUARY 2023
NEWS
Reaching New Levels in Groundwater Monitoring
C
limate change is contributing to severe
droughts in the southwestern United
States and elsewhere, increasing the
afflicted areas’ dependence on groundwater.
In California, for instance, groundwater con-
tributes up to 60% of the state’s total water
supply in dry years.
Small vibrations of Earth’s
surface “contain a wealth
of information about the
subsurface—if we can
use them.”
Monitoring subterranean aquifers is crucial
to using their water efficiently—and ensuring
that the supply doesn’t run dry. The aquifers beneath Los Angeles were one of three sets monitored using a new interferometry technique.
But monitoring groundwater isn’t easy. Credit: Ron Reiring/Flickr, CC BY 2.0 (bit.ly/ccby2-0)
Traditionally, an aquifer’s water levels are
measured using wells: Hydrologists drill into
the ground and measure the pore pressure at
depth, a measurement from which they infer map the inner workings of aquifers? No. For reserves more depleted in hot, dry summer
the amount of water trapped in sediments. her research, coauthor Shujuan Mao used months. Zooming out to longer timescales, the
But drilling is expensive, and the measure- records of so-called seismic ambient noise. researchers noted an overall decreasing trend
ments produce at best a scattered, incomplete “The Earth’s surface is always vibrating due from 2000 to 2020, demonstrating that
image of an aquifer. Alternatively, satellite to ocean waves or human activity,” explained groundwater reserves were depleted more
data can be used to trace deformations of Mao, a postdoctoral researcher in geophysics rapidly than they could recover.
Earth’s surface, which swells up when the at Stanford University. “Those vibrations are This result wasn’t unexpected, given the
ground is waterlogged and subsides as water very small, so we don’t notice them, but they severe drought that gripped California from
drains out, but surface data can’t provide are recorded continuously by seismic stations 2011 to 2017. But Mao and her group observed
insight into what’s underground. and contain a wealth of information about another trend that surprised them: While
Earth’s subsurface—if we can use them.” the San Gabriel and LA Central basins store
Waves, Fast and Slow In their paper, Mao and her coauthors did less groundwater today than 20 years ago,
Now, a new method may sidestep these prob- just that. “What’s unique about our paper is the Santa Ana basin showed a slight increase
lems by exploiting another source of infor- that we not only measure the temporal in aquifer storage since 2000. Because there
mation: seismic data. In a study published in changes [of relative seismic velocity] but also is no natural barrier between the LA Central
Nature Communications, researchers made use image those changes in space,” she said. This and Santa Ana basins, researchers concluded
of the fact that a seismic wave’s velocity is imaging enabled them to construct a high- that the difference is probably geopolitical:
related to the mechanical properties of the resolution map of groundwater distribution In Santa Ana, sustainable water manage-
medium through which it travels (bit.ly/ across 3D space and time. ment strategies ensure that pumping is
groundwater-fluctuations). If the traversed adjusted to the amount of rainfall in a given
sediments are dry, waves propagate rapidly. Pumping Strategies Affect year. In dry years, less water is pumped out,
If the sediments are saturated with water, Groundwater Storage reducing the strain on aquifers. In contrast,
wave speed is reduced. By analyzing differ- The researchers used their method to examine LA Central and San Gabriel tend to use more
ences in seismic wave velocities (a technique aquifers in the Los Angeles (LA Central) and
called interferometry), scientists can back neighboring Santa Ana and San Gabriel basins,
calculate how much water is stored under- using data from about 50 seismic stations
ground. operated by the Southern California Earth- u Read the latest news
Because the method uses seismic waves, do quake Data Center. They found that ground- at Eos.org
scientists need to wait for big earthquakes to water storage fluctuates seasonally, with
SCIENCE NEWS BY AGU // Eos.org 7
NEWS
water than is naturally replenished, leading
to long-term depletion.
Not Your Childhood Water Cycle
Although the dwindling status of ground-
water reserves is worrying, Mao noted that
her research has a silver lining: “In a way, the
differences between counties are encouraging
because they show that w ell-managed pump-
ing strategies have a big impact.” She is opti-
mistic about the method’s potential for
informing those strategies. “It’s not that we
shouldn’t use groundwater, it’s just that we
need a d ata-informed framework to decide
when and how much to pump,” she said.
“Well-managed
groundwater pumping
strategies have a big
impact.”
A Promising Tool for Probing
the Subsurface
I
Ryan Smith, an assistant professor of civil t’s a sight most remember from childhood: comes from data tracking the significant paths
and environmental engineering at Colorado a drawing showing the path of water from and pools of water worldwide.
State University who was not involved with oceans to clouds to rivers. Long, lavish “I think overall, this is a great improvement
the study, also considers seismic interfer- words like evapotranspiration and precipita- and an important step toward a more compre-
ometry to be a promising technique. “The tion likely come to mind. hensive depiction of the global water cycle,”
paper highlights an exciting new method The U.S. Geological Survey (USGS) water
and shows that it can be used to track cycle diagram is still used by hundreds of
groundwater levels in some regions with thousands of students in the United States and
surprisingly good accuracy,” he said, while around the world. It’s also the basis for many,
noting that “since it’s a new area of research, many spin-off diagrams.
The new diagram is the
more investigation needs to be done on how In mid-October 2022, the agency released a first time humans have
passive seismic interferometry relates to new diagram for the first time in more than
changes in groundwater within different 20 years, this time with humans as show
been included in what was
systems.” runners. previously presented as
Smith concluded that with further devel- Although people have long siphoned
opment, “passive seismic interferometry has water from groundwater and diverted rivers
a “natural” cycle.
great potential to complement existing into farm fields and industrial plants, the
approaches for monitoring groundwater.” new diagram is the first time humans have
In her research, Mao continues to refine been included in what was presented until
seismic interferometry as a tool for ground- now as a “natural” cycle. said ecohydrologist and biogeochemist Stefan
water monitoring but is also excited to apply The change reflects the latest 20 years of Krause of the University of Birmingham, who
it to other problems. “This technique can be research uncovering humanity’s central role was not involved in creating the diagram. In
applied to many systems, like geothermal in the cycle and how to communicate it visu- 2019, Krause contributed to a Nature Geoscience
fluid operations, freezing and thawing pro- ally. “We need to change how we think about paper that called into question the lack of
cesses in permafrost, and fracking,” she these things to be able to live and use water human activity or infrastructure in water cycle
Hayley Corson-Dosch/USGS VizLab
explained. “With this profound data set— sustainably for our future,” said Cee Nell, a diagrams (bit.ly/water-cycle-humans). Of 464
temporally continuous and in 3D—there are data visualization specialist at the USGS diagrams analyzed, only 15% included human
a lot of problems in the shallow subsurface VizLab, which designed the diagram. interaction with water.
that we can explore.” In addition to natural processes like ocean “One misconception that could stem from
evaporation, precipitation over land, and run- diagram design is that the water cycle is just
off, the new diagram features grazing, urban one big cycle,” said Nell. The older USGS dia-
By Caroline Hasler (@carbonbasedcary), runoff, domestic and industrial water use, and gram showed a giant loop with arrows for
Science Writer other human activities. Each label in the chart water movement, for example. “We wanted to
8 Eos // JANUARY 2023NEWS
The older water cycle diagram, used by the USGS since 2000, did not include human interference. Credit: Howard Perlman and John Evans/USGS
communicate that the water cycle is actually coolant, said Nell. The water then travels back “We want people to see
composed of many, many smaller cycles that into the stream, sometimes affecting water
are continuously going in different direc- quality. A thermoelectric plant was included the water; everything else
tions.” Arrows in the new diagram are given a in the diagram, as well as other features that is secondary. The details
visual prominence similar to labels of pools aren’t labeled. “There are a lot of hidden Eas-
where water is stored. ter eggs in there for somebody who really are nice, but those
wants to spend time looking,” said Nell.
are going to be less
Krause said he wishes there were nods to
other aspects of human activity, such as alter- visually prominent.
“There are a lot of hidden ing rivers by straightening channels or using
green water, as well as more explanation of
The water is the main
Easter eggs in there for some illustrations. message.”
Accessibility drove the diagram’s design,
somebody who really wants too. Using only one color, blue, alongside a
to spend time looking.” gray scale for labels and landscapes creates a
high contrast for visually impaired people, said but those are going to be less visually prom-
Nell. The illustration’s target age group is inent,” said Nell. “The water is the main
eighth grade, and it will eventually be trans- message.”
lated into 60 languages. For now, it is available
One of the most significant ways people use in English and Spanish.
water in the United States is in thermoelectric “We want people to see the water; every- By Jenessa Duncombe (@jrdscience), Staff
power plants, where stream water is used as a thing else is secondary. The details are nice, Writer
SCIENCE NEWS BY AGU // Eos.org 9NEWS
Indian Cities Invest in Low-Cost Air Quality Sensors
I
n 2019, the government of India estab- precision and can achieve an accuracy of data. Damodar Bachani, deputy project direc-
lished the National Clean Air Programme 80%–90% compared to the RGMs” (bit.ly/ tor at John Snow India, said, “The idea of
for nonattainment cities (cities that did not PM2-5-LCSs). Low-cost sensors are more using social workers was to educate people,
meet the National Ambient Air Quality Stan- maneuverable than RGMs, he noted, which particularly the urban poor, who don’t know
dards). The program aimed to develop clean allows them to have a higher temporal reso- much about air pollution, so that they can
air action plans to reduce particulate matter lution and provide more specific geographic take action to reduce it.”
(PM2.5 ) pollution by 20%–30% by 2024. So far, data. Data from sensors installed at 19 sites in
this effort has been largely ineffective. However, the LCSs “need to be calibrated Indore showed that sources of pollution var-
The program’s inefficiency is partly due to against RGMs before use,” said Pratima ied from place to place. The main source of
a critical shortage of government air quality Singh, an air pollution scientist at the Center pollution was vehicles in commercial areas,
monitoring stations. Experts estimated that for Study of Science, Technology and Policy manufacturing waste in industrial areas, and
India needs 1,600–4,000 monitors. However, (CSTEP), Bengaluru. “There has to be a stan- the burning of biofuels in residential areas.
there are just 883 monitoring stations for dard framework on using these devices.”
assessing long-term air quality trends and CSTEP assessed the performance of various
261 Continuous Ambient Air Quality Monitor- PM2.5 LCSs by comparing them with RGMs.
ing Stations, also known as Reference Grade They found that LCSs match the government
Monitors (RGMs), that report the daily air sensors qualitatively but not quantitatively.
“This community-based
quality index across the country. The discrep- approach shows that you
ancy has resulted in gaps in data and under- Working with Local Clean Air Guides
informed mitigation approaches. Tripathi said that cities are more inclined to
just can’t take common
In 2021, the Commission for Air Quality use LCSs after his team’s cautiously encour- decisions for the entire city,
Management, an agency that manages air aging results. Studies are currently underway
quality in Delhi and the surrounding areas, to use LCSs (in addition to RGMs) to assess air as sources vary, and
recommended the use of low-cost sensors quality in Chennai, Jaipur, Guwahati, and therefore strategies
(LCSs) to address this discrepancy, but other urban areas. “We have interesting
approval is pending because of misgivings observations that we would not get from the to reduce pollution
about the accuracy and reliability of these limited number of government monitors,” he will also vary.”
sensors. added.
To test the precision and accuracy of low- For example, Smart Cities Mission, a fed-
cost PM2.5 sensors, scientists from the Indian eral initiative to promote sustainable devel-
Institute of Technology (IIT) Kanpur installed opment in cities, is using LCSs to quantify
40 sensors next to government RGMs in pollution at local levels. In 2021, Smart Cities “This c ommunity-based approach shows
Mumbai. The Maharashtra Pollution Control Mission partnered with John Snow India, a that you just can’t take common decisions for
Board conducted this pilot project from health care consultant, to identify air pollu- the entire city, as sources vary, and therefore
November 2020 to July 2021. The results were tion hot spots in Indore, a city of about 2 mil- strategies to reduce pollution will also vary,”
published in IEEE Sensors Journal. lion in the state of Madhya Pradesh. said Bachani.
S. N. Tripathi, a study coauthor and profes- As part of the initiative, 20 community For example, in places where the pollution
sor of civil engineering at IIT Kanpur, said, social workers were engaged as “clean air levels were high because of traffic congestion,
“Our study shows that PM2.5 LCSs have high guides” and trained to use and interpret LCS the city initiated a campaign called “Red Light
On, Engine Off,” which urged people to
switch off their vehicles while waiting at traf-
fic lights. The campaign witnessed a 20-point
reduction in emissions.
Education efforts by clean air guides also
influenced behavior in the community. Peo-
ple shifted to wet sweeping from dry sweep-
ing, walking short distances rather than using
transport, and planting more trees. Clean air
guides also reported reductions in the burn-
ing of waste and the use of biofuels in slums
and eateries.
Tripathi said the next steps are to test LCSs
in rural areas to better understand rural air
quality and the relationship between sources
of pollution in rural and urban areas. Most
The efficiency of low-cost air quality sensors is being tested throughout urban areas in India, including Mumbai. rural areas lack government-run monitoring
Credit: Ikshit Patel, Unsplash stations.
10 Eos // JANUARY 2023NEWS
Long-Gone Moon Could Explain
Birth of Saturn’s Rings
A
caterpillar emerges from its chrysa- giant planets should have developed with a
lis as a butterfly, ready to dazzle the tilt of near zero, yet Saturn tips at an angle of
world with its beautiful wings. And 26.7°.
according to a recent study in Science, a chrys- “Saturn is a massive planet, so it takes a
alis at Saturn underwent its own transforma- massive force to tilt it like that,” said Burk
tion (bit.ly/Chrysalis-moon). Today the pul- hard Militzer, a professor of Earth and plan-
verized remains of a small moon—named etary science at the University of California,
Chrysalis by the study’s authors—are daz- Berkeley and a coauthor of the study. “Jack
zling the rest of the solar system as the plan- Wisdom said that even though it’s far, far
et’s beautiful rings. The study argues that away, Neptune could do the job.”
that scenario would explain not only the birth A resonance between a wobble in Nep-
of the rings but Saturn’s tilted axis as well. tune’s orbit and a wobble in Saturn’s rotation
“It’s always nice to find solutions that can on its axis could have applied enough torque
elegantly explain multiple different observa- to change the axial tilt. Wisdom and others
tions,” said Tracy Becker, a planetary scien- suggested that Saturn’s largest moon, Titan,
tist at the Southwest Research Institute in San could also have played a part in that process.
Antonio who studies Saturn’s rings but was
not involved in the new research. “It could A Possible Moon Comes to the Rescue
explain Saturn’s obliquity and the age and Dynamical simulations show that Saturn and
formation of the rings.” Neptune are not in resonance today. How-
The project began with Jack Wisdom, a pro- ever, “it’s very close—about 1% away,” said
ow-cost air quality sensors were installed at 19 sites
L fessor of planetary science at the Massachu- Wisdom. “We argued that because it’s so
in the city of Indore and recorded varied sources of setts Institute of Technology, and his col- close, it couldn’t have been by chance.”
air pollution. Credit: Neeraj Mishra, John Snow India league studying Saturn’s obliquity, or the “We were always so close” to an explana-
planet’s tilt on its axis. Saturn and the other tion, said Militzer, who studies the interiors
Identifying Local Hot Spots
Pilot studies conducted with LCSs in rural
parts of the Indo-Gangetic plain already have
shown that PM2.5 levels are quite comparable
in different settlements across the region,
irrespective of the settlement type—village,
town, city.
Saumya Singh, a postdoctoral researcher at
the University of California, Berkeley and lead
author of the new study, said, “Low-cost sen-
sors are helping us understand the urban-
rural gradient. These results suggest that we
need additional observations in rural settings
about source dynamics and concentrations
of PM2.5.”
Pratima Singh agreed that LCSs have their
advantages, and CSTEP has installed a net-
work of them in Bengaluru, Punjab, and Delhi
to study different aspects of air pollution.
“Low-cost sensors have a high temporal
resolution that helps identify hot spots at
local levels, which RGMs cannot because of
their incapability to be moved around,” she
said.
Titan passes in front of Saturn in this view from the Cassini spacecraft, with the e
dge-on rings forming a thin stripe
By Deepa Padmanaban (@deepa_padma), and thick series of shadows. Titan could have played a crucial role in the rings’ formation. Credit: NASA/JPL-Caltech/
Science Writer Space Science Institute
SCIENCE NEWS BY AGU // Eos.org 11NEWS
of Saturn and other outer solar system giants. drastically altering the smaller satellite’s dis- sus that they formed from the icy debris of
“It went on for weeks, and it was a big misery. tance from Saturn and creating closer and one or more pulverized bodies—small moons
What could get us to the critical value? Then closer encounters with Titan and Iapetus. or passing comets. There’s less consensus on
the concept of this moon appeared. At that About 100 million years ago, its eccentricity the age of the rings, however. Some have
moment, what had been a problem became a doomed Chrysalis to being kicked out of the argued that the rings formed not long after
real opportunity.” Saturnian system, causing it to crash into Saturn itself did. Cassini observations, along
“You could add an extra satellite, and that Titan or another moon or bringing it so close with other work, suggest that the rings are
would allow the obliquity to rise due to the to Saturn that it would be ripped apart. much younger—perhaps 100 million or so
resonance with Neptune as Titan migrated years, matching the time frame for the disin-
outward,” said Wisdom. tegration of Chrysalis.
Observations from NASA’s Cassini space- “This study predicts the breakup of a moon
craft, which orbited Saturn from 2004 to 2017,
showed that Titan is moving away from Sat-
Chrysalis’s orbit was at around the time a lot of evidence is show-
ing the rings might have been formed and
urn at a rate of about 11 centimeters per year. pumped to a higher gives a mechanism for how it happened,” said
As Titan migrated outward, it altered Saturn’s
axial precession—a wobble that causes the
and higher eccentricity, Becker.
According to Wisdom, Chrysalis disinte-
axis to trace a big circle on the sky. Changes drastically altering the grated when it passed by Saturn at roughly
in the precession rate brought Saturn and the same distance away as the planet’s diam-
Neptune into resonance. “About a billion
smaller satellite’s distance eter. At that range, the side of Chrysalis closer
years ago, Saturn entered the resonance with from Saturn and creating to Saturn faced a stronger gravitational pull
Neptune just by the migration of Titan,” Wis- than the other side. The difference created
dom said.
closer and closer powerful tides (just as the Moon creates ocean
Simulations showed that the hypothetical encounters with Titan tides on Earth) that ripped the moon to
moon, Chrysalis, probably orbited between shreds. Much of its debris fell into Saturn, and
Titan and Iapetus, Saturn’s t hird-largest
and Iapetus. the rest spread out over the following hun-
moon (though it’s only about a quarter the dred thousand years or so to form the rings.
diameter of Titan). Chrysalis was likely a little With Chrysalis gone, Saturn’s resonance
less massive than Iapetus, according to the with Neptune was broken. “Titan is continu-
study, and probably consisted mainly of water Wisdom’s simulations didn’t necessarily ing to recede, but as it recedes, the system
ice. favor any of those scenarios. But one other gets farther from resonance, so [Saturn’s]
As Titan receded from Saturn, it created a factor argued for destruction by Saturn: the obliquity is no longer increasing,” Wisdom
3:1 orbital resonance with Chrysalis, Wisdom planet’s rings. said. And Saturn retains its magnificent rings,
said, which increased Saturn’s tilt to as much which might have emerged from a long-gone
as 36°. As Chrysalis Disintegrates, So Does chrysalis.
The T itan-Chrysalis resonance made the the Resonance
moon system chaotic. Chrysalis’s orbit was Scientists have long debated the origin and
pumped to a higher and higher eccentricity, age of Saturn’s rings. Today there’s a consen- By Damond Benningfield, Science Writer
12 Eos // JANUARY 2023NEWS
Neighborhood Strategies Inform Boston’s First
Urban Forest Plan
M
attapan, a neighborhood in south-
western Boston, is heating up.
Although some areas of the residen-
tial neighborhood benefit from the cooling
effects of nearby green spaces, others are vul-
nerable to increasing heat stress, largely
because of dark roofs, unshaded parking lots
and pavements, and wide streets with limited
numbers of trees.
Mattapan is one of five Boston neighbor-
hoods identified as being at particular risk
for heat stress. (The others are Chinatown, Boston has recognized the importance of healthy tree coverage in addressing heat resilience and other climate
Dorchester, East Boston, and Roxbury.) The change mitigation strategies. Credit: Mark Olsen/Unsplash
five neighborhoods, all environmental jus-
tice communities, are at the focus of Boston’s
heat resilience strategies, which include
increasing the amount of light-colored sur- “This plan essentially provides an analy- cabinet to participate on its own schedule and
faces and shade. sis of the conditions in each neighborhood,” its members to interact with one another.
A big reason for the risk is the simple fact said Neenah Estrella-Luna, the principal “That technique pushed for consensus build-
that there are fewer trees in these neighbor- of S tarLuna Consulting, a social equity ing, as opposed to just whoever talks the most
hoods. For example, less than 25% of the land researcher, and a consultant on the plan. or the loudest, which often is how decisions
in East Boston (excluding Boston Logan Inter- get made,” said Amy Whitesides, director of
national Airport) has adequate tree coverage. Neighborhood Strategies resilience and research at Stoss Landscape
The plan’s “neighborhood strategies” Urbanism and a consultant on the urban for-
approach considers the unique ways in which est plan.
each neighborhood has the ability to address The neighborhood strategies approach also
The plan’s “neighborhood particular issues and identifies the people helped inform the plan’s four goals: equity,
within that neighborhood who are able to community-driven processes, making sure
strategies” approach do something about them. The approach trees are valued and prioritized, and proactive
considers the unique employs the help of urban forest nonprofits
like Dorchester-based Speak for the Trees,
care and preservation of existing trees. The
last tenet was especially important, Estrella-
ways in which each whose focus is on increasing the size and Luna explained. Before the drafting of the
health of Boston’s urban forest, particularly plan, “there just weren’t sufficient resources
neighborhood has in undercanopied areas. Neighborhood devoted to particularly proactive protection
the ability to address strategies may also take inspiration from of the existing canopy in historically excluded
Lower R oxbury–based Friends of Melnea neighborhoods.”
particular issues Cass Boulevard, which stopped a $25.6 mil- In spring 2022, the city halted renovation
and identifies the people lion construction project that would have plans for Malcolm X Park, located in Dorches-
removed 124 mature trees, the Boston Globe ter, after outcry from residents. The plan
within that neighborhood reported. threatened to remove 54 trees, many of which
who are able to do This approach was driven entirely by the are more than a century old.
urban forest plan’s equity council—a part of Hunter Jones, manager of the Climate and
something about them. the larger community advisory board—and Health Project within NOAA’s Climate Pro-
composed of individuals from historically gram Office, noted that Boston’s neighbor-
excluded and currently marginalized com hood strategies approach is part of a larger
munities across the city. The plan’s consul- trend in the United States. Jones identified air
Boston has recognized the importance of tant team organized a series of focus groups, temperature, humidity, and even wind speed
healthy tree coverage in addressing heat resil- which sent out a series of surveys to the as factors contributing to urban heat and
ience and other climate change mitigation equity council to establish overarching goals, air quality issues across the country. “But
strategies. In fact, the city developed its first the best strategic approach, protection regu- increasingly,” he said, “there’s interest in
urban forest plan—a pathway to maintaining lations, expectations for the level of involve- looking at intracity differences.”
existing trees, planting new ones, and other- ment from stakeholders, and more.
wise helping the city deal with the effects of a Responses were summarized and con
changing climate (bit . ly/ B oston - forest solidated and went through three rounds of By Iris Crawford (@IrisMCrawford), Science
-plan). refinement, a process that allowed the equity Writer
SCIENCE NEWS BY AGU // Eos.org 13NEWS
Seafloor Reveals a Period of Rapid Retreat
for Thwaites Glacier
A
ntarctica’s Thwaites Glacier suffered ration (ITGC), was launched in 2017 to reveal “In general, [the ridges are in] quite deep
a period of fast retreat, doubling its the glacier’s past and predict its future. water, so they are below the reach of the main
current rate of shrinking, during the tidal currents and wave action,” said Robert
past several hundred years. This is the con- Telltale Ridges Larter, a marine geophysicist with the British
clusion reached by an international group of In 2019, an expedition on board the Nathan- Antarctic Survey who was the lead scientist
researchers who acquired high-resolution iel B. Palmer icebreaker approached the front on board the Nathaniel B. Palmer during
imagery off the front of Thwaites. The group of the glacier and released a remotely oper- the expedition. “And in many areas of the
used state-of-the-art autonomous submers- ated submersible that mapped an area of polar continental shelf there are very low
ibles, which revealed unusual marks left on 13 square kilometers of the seabed with spe- rates of sediment accumulation, so [the
the seafloor by the retreating ice. cialized sonar and other instruments. As ridges] don’t get buried, either.”
soon as the researchers recovered the sub- By looking at the ribs, the researchers real-
mersible and looked at the images, they ized they had a daily record of Thwaites’s
realized they had made an extraordinary retreat over a period of 5.5 months. During
“It was like putting on your finding. “None of us could explain what we
were seeing,” said Alastair Graham, an asso-
that time, the glacier moved at a rate of
2.1 kilometers per year, twice the current rate
glasses for the first time ciate professor of geological oceanography as measured by satellite imagery.
and being able to see.” at the University of South Florida and lead
author of the new study. “It was like putting
Coming up with the mechanism that
produced the ribs wasn’t straightforward,
on your glasses for the first time and being though. The marks were so regularly spaced
able to see.” that they looked “made by humans,” Graham
The images showed hundreds of parallel said. “It took a long time for us to settle on an
As large as Florida and several kilometers ridges covering an underwater plateau at idea for what they might be and why they
thick, Thwaites is one of the main concerns depths ranging from 630 to 670 meters. The are forming.” His analysis showed that the
of scientists studying the Antarctic ice sheet. researchers think this plateau was a pinning amplitude and height of the ridges follow a
The melting of this mass of ice is responsible point at a former grounding line, a region pattern that matches the region’s natural
for 4% of present-day sea level rise world- where the land-based glacier ends and the tidal cycles, reaching a maximum in ampli-
wide. And warming waters and a seabed that floating ice shelf begins. The ridges, ranging tude and height every 14 days. The findings
deepens toward the ice sheet’s interior have from 10 to 70 centimeters tall, were likely were reported in Nature Geoscience (bit .ly/
primed the glacier for a rapid collapse that created by the glacier’s front as it bobbed up Thwaites-retreat).
could raise sea levels by more than half a and down with the tides. When the tide fell, The researchers don’t know when exactly
meter in the next century. the glacier pressed the sediments to produce the ridges formed, but on the basis of
Scientists don’t know enough about the one rib. The distance between ribs reveals Thwaites’s current rate of retreat, they think
glacier’s recent history to confidently forecast how much the glacier receded during the the ridges aren’t older than 200 years. Most
its future behavior, however. That’s why a daily tidal cycle—typically between 6 and likely, they formed around the 1940s, when
large British-American research initiative, 7 meters every day, but reaching up to neighboring Pine Island Glacier started
the International Thwaites Glacier Collabo- 10 meters in some cases. retreating. A direct sample of the seafloor
The underwater robot Ran operated at the ice front of Thwaites Glacier from R/V Nathaniel B. Palmer in 2019. Credit: Filip Stedt, University of Gothenburg
14 Eos // JANUARY 2023You can also read
