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Humans Colonized Polynesia Much Earlier Than Previously Thought

Wed, 05/13/2020 - 12:27

“It’s not an easy feat finding tiny islands scattered in a body of water that can engulf all seven continents with room to spare.” The last great migration of humans to lands unknown occurred with the colonization of East Polynesia about a millennium ago. It’s not an easy feat finding tiny islands scattered in a body of water that can engulf all seven continents with room to spare.

“In terms of the scale, risk, and magnitude of the exploration, it’s one of humanity’s momentous achievements,” said Barry Rolett, an anthropologist at the University of Hawaiʻi at Mānoa.

But the details of this accomplishment—and what drove it—have been shrouded in mystery.

Now, a new study published in the journal Proceedings of the National Academy of Sciences of the United States of America reports that humans arrived in East Polynesia 200 to 300 years earlier than previously thought.

Their arrival in East Polynesia—a culturally and linguistically distinct region spanning from the Cook Islands to Rapa Nui and Hawaii—coincides with a time of prolonged drought in their West Polynesia islands of origin in Tonga and Samoa, which may have helped spur the dangerous excursions eastward.

“It’s an impressive study and an important one,” said Rolett, who was not involved in the research. “It’s unusual for Polynesia because there hasn’t been a lot of paleoenvironmental reconstruction work done in this area.”

Tracking Human Settlement Through Mud, Charcoal, and Feces

Lake sediments and mud can be used as archives of both human environmental impact and the climate across the centuries, said David Sear, a professor of physical geography at the University of Southampton in the United Kingdom and the lead author on the new study. “We wanted to go and collect data along the route of the human colonization story of the Pacific and follow that story in the mud from the lakes and bogs.”

Because of how remote the islands are, the researchers had to bring their own inflatable boats, build their own rafts, and transport all their equipment by hand via muddy jungle paths to drill and collect cores of mud from each island’s lake. The team initially collected mud cores from Lake Te Roto on Atiu, a part of the Southern Cook Islands.

After collecting mud cores, Sear and his colleagues stored them in aluminum tubes. “You pack them into a cardboard box very carefully, put ‘fragile’ on the outside, go to the post office, pay 200 quid, and get it flown back to the U.K. under special import-export licenses, of course,” he said.

Back in the lab, researchers scanned the mud for multiple proxies of human activity, including charcoal, which is a sign of fire, and titanium, which indicates soil erosion; together, they indicate deforestation of the trees and underbrush native to the island. But the most telltale sign of human presence they looked for was something even more fundamental: feces. Specifically, fecal sterols, a fatty substance found in mammalian feces. On these remote Pacific islands, there were no mammals besides fruit bats prior to the arrival of humans and pigs.

“The idea of using fecal markers is really innovative, and it works extremely well,” said Rolett.

Together, the evidence points to an incremental migration process with humans first arriving in East Polynesia around 900 CE, followed by increased settlement activity over the next 200 years. This study “fills in a really important part of the puzzle of human settlement,” said Melinda Allen, an archaeologist at the University of Auckland in New Zealand and coauthor on the study. “And a lot of unconnected strands of evidence can now be pulled together as a result of these findings.”

Climate Change and Migration The vessel in the middle of Lake Lanoto’o, Samoa, is the coring raft researchers used when extracting sediment samples. Credit: David Sear, University of Southampton

. An extended regional drought in West Polynesia may have driven the human forays east. The researchers reconstructed regional paleoclimatic conditions of the past 2,000 years using additional lake core samples taken from islands in Samoa and Vanuatu, as well as previously published records of the Society Islands of French Polynesia. They found that the timing of human arrival in East Polynesia coincides with an intense, prolonged drought—the driest period in 2 millennia—which the researchers suggest helped drive people to migrate.

However, there are likely other factors that might have led to settlement in addition to or in conjunction with drought, said Seth Quintus, an anthropologist at the University of Hawaiʻi at Mānoa who was not involved in the current study. “It’s really hard to say that drought is what’s causing the movement of people.”

As a whole, the study “teaches us a lot about how people in the past manage and respond to different risks in their environment,” he added.

Pacific Climate Change Past and Future

Sear said that there are still more climate data to analyze from the mud cores once the labs are back open: The records his team collected go back 10,000 years, and this study looked at only the most recent 2,000. Understanding how climate has changed in the Pacific Ocean is crucial because it is “one of the big engines of the global climate system,” Sear said, and there are not many climate data from before the 1950s.

“If we can get a better understanding of both how their ancestors changed the landscape and the climate story that goes along with that, it will help them manage their future.”Better understanding of the region’s climate system would not only shed light on the area’s past but benefit the almost 12 million people living in the region today.

“These people are being squeezed by rising sea levels, changes in precipitation, increasing temperatures,” Sear said. “When you put that together, they’re amongst the most vulnerable people on the planet.”

“If we can get a better understanding of both how their ancestors changed the landscape and the climate story that goes along with that, it will help them manage their future,” Sear said. “Because, of course, one of their responses to climate change in the past is to get into a canoe and move somewhere else.”

“You can’t do that anymore,” he said. “That major adaptation strategy is no longer is available to them.”

—Richard J. Sima (@richardsima), Science Writer

How Routine Monitors Weather the Pandemic Storm

Wed, 05/13/2020 - 12:22

People throughout much of the United States have been heavily encouraged to shelter in place since mid-March to prevent the spread of coronavirus disease 2019 (COVID-19), the disease caused by the novel coronavirus. The global pandemic has shuttered labs, interrupted field work, and forced scientists to delay field campaigns that were planned for years.

But the processes that shape Earth and its ecosystems, like the rising and falling of tides, the shifting of underground rock, and algae blooming in the ocean, have not come to a halt. And these processes—some of which can lead to more loss of life—require routine monitoring.

Routine monitoring involves collecting real-time data with a suite of instruments and in situ observations. Some sensors can be left for months or years at a time, but they also might fail or need maintenance. And during a time when all of us are told to stay at home, when scientists are forced to delay field work and research campaigns, what does that mean for the monitors?


“Earthquakes do not stop during epidemics,” said Lucia Margheriti, senior researcher at the Istituto Nazionale di Geofisica e Vulcanologia in Rome. Starting 8 March, the Italian government issued strict stay-at-home orders, and Margheriti and her team began working remotely. However, a team must be on site in the lab at all times, so the group has implemented extreme cleaning and social distancing protocols when in the same building.

“One thing that came up very early was just the fact that you can’t shut down monitoring because it’s a public safety system.”Shelter-in-place orders haven’t affected day-to-day monitoring operations for seismologists working for the Pacific Northwest Seismic Network (PNSN). After all, earthquakes can happen any time of day or night, said Harold Tobin, PNSN’s director and Washington’s official state seismologist, so seismologists have protocols in place for when an earthquake occurs outside normal working hours. Even without shelter-in-place orders, there’s always an “on-duty” seismologist ready to be woken up at 2:00 a.m. to respond to an emergency.

“One thing that came up very early was just the fact that you can’t shut down monitoring because it’s a public safety system,” Tobin said.

However, the pandemic has interrupted the rollout of ShakeAlert, a system that will provide up to tens of seconds of warning before an earthquake in Oregon and Washington (California’s ShakeAlert network went online at the end of 2019). The system requires at least 100 more seismic stations to be complete, Tobin said. That involves groups of people working together, conducting site visits, and installing equipment within close quarters.

Amid the new era of social distancing, the ShakeAlert scientists won’t be able to install new stations. The U.S. Geological Survey had planned to publicly roll out ShakeAlert this fall, but with the delay in new seismic stations and the fact that Washington’s state emergency team had to turn their focus to the spreading pandemic, ShakeAlert will have to wait.

The Coast

In Pacific Northwest waterways, buoys in need of maintenance have been left unattended, and buoys ready for deployment can’t go out yet, said oceanographer Jan Newton. She’s the executive director for a regional branch of the Integrated Ocean Observing System (IOOS), which uses various sensors to provide real-time data for things like acidification, temperature, wind speeds, and tides to private and public entities.

A single buoy could be simultaneously providing acidification data, temperature data, meteorological data, and phytoplankton data.Newton describes IOOS as a set of “scientific oceanographic observations, but with the intention of societal benefit”—the oceanographic version of the National Weather Service.

A single buoy in Washington state’s Puget Sound, for instance, could be simultaneously providing acidification data for shellfish growers, temperature data for scientific models, meteorological data for navigation purposes, and phytoplankton data to track the development of harmful algal blooms.

“People do depend on these data for things like safe navigation for things like making their livelihood,” Newton said.

With shelter-in-place orders, IOOS employees can’t do routine maintenance on their gear, some of it aging and without a replacement. For instance, an ocean acidification buoy was supposed to deploy this month, but its instruments won’t be recalibrated in time because the sensor industries are also affected by shelter-in-place protocols.

Small industries, like mom-and-pop companies that take customers out fishing, “are going to be the ones that need to be fully functional,” Newton said.

The Mountains

“Being alone is safest, but given the realities of our environment, being with another person is ultimately more safe.”For Amanda Henderson and her colleagues at the Rocky Mountain Biological Laboratory, situated about 320 kilometers southwest of Denver, some monitoring work involves hiking or cross-country skiing into remote locations to measure vegetation or snowmelt. And doing field work during a pandemic brings up a tricky conundrum.

“Being alone is safest, but given the realities of our environment, being with another person is ultimately more safe,” said Henderson, who studies snowmelt around Gunnison County in the spring to understand how it affects the local waterways and, ultimately, the Colorado River. Some of her colleagues have to cross-country ski nearly 20 kilometers to get to their study site. In that case, they decided to drive to the trailhead separately and maintain the recommended 2 meters apart while working.

Henderson’s own snowmelt monitoring work can be done solo, she said, so she’s comfortable 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 network that’s been in place since 1891. Across the United States, thousands of volunteers take daily weather measurements of temperature 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 different regions across the United States. And these records can be used by a number of groups, including scientists studying climate change and insurance companies needing to confirm that damage to a car was from hail, Kelsch said.

Weather forecasts could still be affected, however. These days, many commercial flights carry weather sensors, and the airline industry has seen a significant drop in traffic since the novel coronavirus came to the United States. For example, the United States saw a 73.3% decrease in air traffic in April 2020 compared to April 2019. On 7 May, the World Meteorological Organization reported a 75%–80% decrease in meteorological observations from flights. (In the Southern Hemisphere, the decrease is close to 90%.) Before the pandemic, commercial flights provided more than 800,000 meteorological observations per day.

“Even though a decrease in this critical data will likely negatively impact forecast model skill, it does not necessarily translate into a reduction in forecast accuracy since National Weather Service meteorologists use an entire suite of observations and guidance to produce an actual forecast,” said National Oceanic and Atmospheric Administration spokesperson Susan Buchanan in a statement released 24 March.

—JoAnna Wendel (@JoAnnaScience), Science Writer

What It’s Like to Social Distance at Sea

Tue, 05/12/2020 - 16:19

Preparation for the research cruise in the northern Gulf of Alaska in May began in an unusual way for chief scientist Russ Hopcroft: 2 weeks of self-quarantine at home with his family.

Since the novel coronavirus put ocean-going research at a standstill, many scientists wonder how they’ll ever sail again. Research cruises have tight quarters, take scientists sometimes weeks away from land, and bring people from all over the world into the same cramped location. In March, the organizational body for U.S. universities, the University-National Oceanographic Laboratory System (UNOLS), halted all research cruises until 1 July.

Oceanographers have returned to the same track for 22 years.That is, except for Hopcroft’s cruise. The weeklong jaunt on the University of Alaska Fairbanks’s (UAF) ship the R/V Sikuliaq was initially planned for 2 weeks in April. Scientists intended to measure the extent of the Gulf of Alaska’s vibrant spring plankton blooms. The annual measurements inform Alaska’s fishery management quotas for next year.

Oceanographers have returned to the same track, called the Seward Line, for 22 years, and missing out this year would have not only starved management agencies of data but caused greater uncertainty in that data.

Alaska has had the lowest number of recorded cases of COVID-19, the disease caused by the novel coronavirus, of any state, according to NPR. Just this week, reported cases ticked up by a few or less per day statewide. Alaskans are well suited for social distancing and staying away from stores, said UAF professor Hopcroft. “This is Alaska. We’re used to having several weeks’ supplies on hand at any one time.”

“It’s Just Kind of Weird”

Being out on the water with so few people is strange, said Hopcroft. The scientists each have their own berthing and bathroom, a luxury for research ships that are usually packed to the brim with scientists, graduate students, technicians, and crew. Every other seat in the ship’s dining area is blocked off too. “It’s just kind of weird to be out here and have the ship so empty.”

Danielson handles equipment for a plankton net tow in front of an empty deck on the 261-foot vessel. Credit: Ethan Roth

Cruise organizers compressed the ship time in half, stayed closer to shore, and reduced the 24-scientist team to just three researchers, each from a unique discipline: biological, chemical, and physical oceanography. The skeleton crew prepared with their colleagues over Zoom, taking instructions on how to collect samples for one another.

Everyone on board takes their temperature and oxygen levels several times a day at a station on the ship, writing the values down on a log sheet. The three scientists self-quarantined for 2 weeks before the cruise and drove the 10 hours from Fairbanks to Seward in personal vehicles with no interaction with the outside world. The crew quarantined for 3 weeks and took COVID-19 tests a few days beforehand.

“This will probably be one of the few data sets being taken this spring up here in the gulf.”The physical oceanographer on the team, UAF associate professor Seth Danielson, said that he didn’t view the cruise as a risk for his personal health because of the extensive precautions taken. If anything, he said, “we’re feeling really lucky to be out right now” given that so many expeditions have been canceled. The cruise organizers coordinated with the U.S. Coast Guard, UNOLS, the World Health Organization, the Centers for Disease Control and Prevention, and health mandates by Alaska’s governor.

UAF associate professor and chemical oceanographer Ana Aguilar-Islas said that being on board has distracted her from the news. “I kind of have forgotten that there’s a pandemic out there. That’s really a welcome change. I don’t find myself checking the [COVID-19 case counts] as much.” Aguilar-Islas said she and her colleagues are working 14–16 hours per day.

Aguilar-Islas works on in one of the ship’s labs. Normally, scientists compete for space on a ship, but Hopcroft said to social distance they have “one person per lab.” Credit: Seth Danielson

Hopcroft said that it was crucial to get these data. “This year, with there being so few other measurements being taken by other colleagues, this will probably be one of the few data sets being taken this spring up here in the gulf.”

Still, future cruise planners will face some tough decisions, Danielson said. With limited people allowed on board, how will graduate students receive field training? Having rapid COVID-19 tests with a high degree of accuracy would help reduce any “room for doubt” of possible infections, Hopcroft said.

“The UAF team demonstrated that seagoing science can be conducted during this time of the pandemic,” Craig Lee, UNOLS chair said. “That said, each cruise presents a unique set of challenges and must thus be assessed individually for risk and mitigation.”

For now, Lee said, cruises that save instruments and data or continue long time series are the most urgent.

—Jenessa Duncombe (@jrdscience), Staff Writer

Using Saturn’s Rings as a Seismometer

Tue, 05/12/2020 - 13:00

Seismology is a powerful tool for probing a planet or star’s interior structure. Almost forty years ago, it was recognized that internal oscillations in Saturn could produce wave patterns in its rings: the rings could act as a seismometer. Now, as Mankovich [2020] describes in a Commentary, twenty such patterns are known, and lead to two surprising conclusions.

The first is that the interior half of Saturn is not convecting, as was expected, but is stably stratified. The explanation is most likely a deep but diffuse rock-rich region. The second conclusion is that Saturn is not only rotating somewhat faster than was previously thought, but that the rotation rate varies with depth. The use of rings as seismometers is still in its infancy, and more is likely to be learned as modeling techniques become more precise. Furthermore, this work opens up the possibility of using similar approaches elsewhere, notably the ring system of Uranus.

Citation: Mankovich, C. [2020]. Saturn’s rings as a seismograph to probe Saturn’s internal structures. AGU Advances, 1, e2019AV000142. https://doi.org/10.1029/2019AV000142

—Francis Nimmo, Editor, AGU Advances

The Closest Black Hole Is 1,000 Light-Years Away

Tue, 05/12/2020 - 11:24

Supermassive black holes—millions or even billions of times more massive than the Sun—anchor the centers of 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 Way. Now researchers have spotted another one of these stellar mass black holes, and it holds a special honor: It’s the closest black hole to Earth yet discovered. The findings shed light on the dynamics of supernova explosions that go on to create black holes, the team suggested.

Finding Wallflowers

Disks of hot gas and dust glowing brightly in X-rays sometimes encircle black holes. This radiation indicates that a black hole is active and accreting matter, said Thomas Rivinius, an astronomer at the European Southern Observatory in Santiago, Chile. And it’s a beacon. “We only find the [black holes] that are violently gobbling up material from their environment,” said Rivinius.

“We thought it was only two stars.”It’s much harder to spot the many black holes that aren’t consuming matter—they don’t produce X-rays. But sometimes the universe aligns itself just right to reveal these wallflower black holes. That’s what Rivinius and his collaborators found when they examined HR 6819, a seemingly ordinary pair of stars about 1,000 light-years away in the constellation Telescopium.

In 2004, Rivinius and his colleagues trained a 2.2-meter telescope in La Silla, Chile, on HR 6819. “We thought it was only two stars,” said Rivinius.

But to their surprise, the researchers discovered that one of the stars was wobbling in a circle. “One of them was being flung around,” said Rivinius. That’s the telltale sign of a companion, a nearby object that’s tugging gravitationally on the observed celestial object. So HR 6819 wasn’t just a pair of stars—it was three objects: one star on a relatively wide orbit and one star paired with something unseen, the team concluded.

Not a Star, White Dwarf, or Neutron Star

The scientists calculated that the mysterious third object in HR 6819 had to be at least about 4 times the mass of the Sun. That’s pretty hefty—a star of that mass would pump out enough light to be visible even if it belonged to the dimmest class of stars, Rivinius and his collaborators estimated. The team also ruled out fainter objects like white dwarfs and neutron stars because they’re typically of much lower mass. That left one logical conclusion: The unseen object was a black hole.

That idea languished for several years, however, after tragedy struck unexpectedly: A team member died in a car accident in June 2014. “The study stalled,” said Rivinius.

But last year, new results spurred Rivinius and his colleagues to revisit their findings. Another team of researchers had reported finding a black hole using the same method. Rivinius remembers seeing a press release and thinking, “Wait a second—I have something in the drawer that looks exactly the same.”

The Closest One

Rivinius and his collaborators estimated that the black hole in HR 6819 was about 1,000 light-years from Earth, making it the closest known black hole. Its proximity implies that systems like this one are common. “Our neighborhood is nothing special,” said Rivinius. “If it’s here, it must be everywhere.”

These results were published this month in Astronomy and Astrophysics.

“There are probably a million black holes in the galaxy that have binary companions that are stars.”The existence of HR 6819 sheds light on the supernova explosions that create black holes, the scientists suggested. It’s long been believed that such explosions are antisymmetric, meaning they send matter flying preferentially in one direction, with the result that the black hole is launched in the other direction. But finding a black hole gravitationally bound to a star implies that in some cases, black holes aren’t flung from their birthplace. That is, supernova explosions are sometimes symmetric.

Determining what fraction of supernovas are symmetric versus antisymmetric will require a larger sample of black holes. That’s entirely possible research, said Todd Thompson, a theoretical astrophysicist at the Ohio State University in Columbus not involved in the research. “There are probably a million black holes in the galaxy that have binary companions that are stars,” said Thompson. “That’s a very big sample that we should get busy trying to understand.”

—Katherine Kornei (@KatherineKornei), Science Writer

Pollution Spikes in Chile Tied to Soccer Fans’ Barbecuing

Mon, 05/11/2020 - 12:32

In 2016, the Chilean national soccer team won a championship match against Argentina in nail-biting overtime. That same day, air pollution levels spiked in Chile’s capital city. Now scientists have figured out why: Santiagans had fired up roughly 100,000 charcoal barbecues while they watched the televised match, and combustion from the grilling triggered record-breaking levels of PM2.5 pollution. (PM2.5 describes atmospheric particulate matter smaller than 2.5 micrometers.) These results suggest that days of poor air quality can be predicted by considering large-scale cultural events.

In Santiago, levels of PM2.5, which can enter the lungs and inhibit respiration, occasionally spike to tenfold above average values for a few hours. Rémy Lapere, an atmospheric chemist at the École Polytechnique in Palaiseau, France, remembers modeling Santiago’s PM2.5 data from June 2016 when he stumbled upon two such spikes. “I had no idea they existed,” he said.

Not the Usual Suspects

“The chemical footprint didn’t add up.”Lapere’s curiosity was piqued, but he and his collaborators quickly ruled out the usual suspects that might have triggered the upticks. Wildfires probably weren’t the cause—no large ones had been reported. (It was winter, after all.) Furthermore, the pollution signal was strongly heterogeneous among Santiago’s 11 meteorological stations—a significant fire would have sent a plume over most of the city. Traffic was also exonerated—a tenfold increase in emissions would have implied a major road snarl, and none were reported during the times of the spikes. Residential heating, another big contributor to PM2.5 pollution, was likewise in the clear—it wasn’t any colder than normal on the days of the spikes, Lapere and his colleagues found.

The team next analyzed concentrations of PM2.5, nitrogen oxides (NOx), and carbon monoxide (CO) during the spikes and at other times. They found significantly lower NOx/CO and NOx/PM2.5 ratios during the spikes than during nonspike times. That’s highly suggestive of different emission sources, the team concluded.

“The chemical footprint didn’t add up,” said Lapere.

“It’s Soccer Games”

Lapere decided to reach out to a Chilean colleague for ideas. The scientist, who happened to be a sports fan, inquired about the dates of the spikes. He knew right away what it was, said Lapere. “It’s soccer games.”

“It’s like putting a running bus in your garden for 3 hours.”Of course, the soccer matches themselves weren’t producing the emissions. They were simply the motivation for a Chilean cultural tradition that happens to create pollution. Chileans tend to celebrate events, including important soccer matches, by barbecuing, said Francisco Barraza, an environmental scientist at the University of Otago in New Zealand not involved in the research who earned his undergraduate and graduate degrees in Chile. Chunks of meat are cooked for multiple hours over charcoal, and all those open fires release particulate matter, said Barraza. “It’s like putting a running bus in your garden for 3 hours.”

The two spikes that Lapere and his collaborators found—18–19 and 26–27 June 2016—corresponded to televised matches of the Copa América, a South American soccer tournament, that involved the Chilean national team: Mexico versus Chile in the quarterfinals and Argentina versus Chile in the championship game, respectively. (Chile would go on to win, 4–2.)

To verify that barbecuing (asado in Chile) was the culprit, Lapere and his colleagues mined published NOx/CO and NOx/PM2.5 ratios associated with barbecuing. They found values consistent with their measurements during the spike events.

A Hundred Thousand Barbecues

A week prior to the championship Argentina versus Chile match, Santiagans were polled about their game day habits, and 29% reported they’d barbecue during the game. Assuming that barbecue gatherings involve roughly seven adults, that translates into about 100,000 barbecues, Lapere and his collaborators estimated. The researchers modeled the PM2.5 emissions from 100,000 barbecues and compared their simulations with the data from 26–27 June.

“The simulation reproduced the observations properly,” said Lapere. In other words, the meteorological data were consistent with the emissions from about 100,000 barbecues, the scientists concluded. These results were published last month in Atmospheric Chemistry and Physics.

Cultural events in other countries have also been shown to be associated with increases in pollution. For instance, Oktoberfest in Munich, Germany, is a significant source of methane, and researchers have measured upticks in PM2.5 levels after Lantern Festival celebrations in Beijing.

—Katherine Kornei (@KatherineKornei), Science Writer

Space Weather Forecasting Takes Inspiration from Meteorology

Mon, 05/11/2020 - 12:31

Every so often, the Sun unleashes powerful bursts of plasma particles and magnetic field structures toward Earth. These solar storms can wreak havoc on power grids, satellites, and other infrastructure, but they are difficult to predict more than a few days in advance.

In a new review, Dikpati and McIntosh showcase mounting evidence that solar storms arise from solar Rossby waves, a type of wave associated with rotating fluids. Just as the 1939 discovery of Rossby waves in Earth’s atmosphere paved the way to accurate weather prediction, Rossby waves in the Sun could be key to predicting disruptive space weather in time to prepare for it.

On Earth, atmospheric Rossby waves arise from the planet’s rotation, and these large-scale meandering features help transport warm air toward the poles and cold air toward the tropics. Earth’s Rossby waves sometimes have extreme effects, such as those from 2019’s polar vortex.

Rossby waves in the solar plasma arise from the star’s rotation and originate within a transitional layer known as the tachocline. Unlike Earth’s Rossby waves, solar Rossby waves are strongly influenced by powerful magnetic fields. Recent observations and theoretical modeling suggest that these magnetically modified Rossby waves interact with the differing rates of rotation of the Sun’s plasma to trigger solar storms.

The researchers suggest that computational techniques developed for meteorology could inform strategies to improve solar storm predictions. In the future, scientists could use observations of the Sun’s surface as indicators of Rossby wave dynamics deep below, potentially revealing harbingers of solar storms weeks, months, or even a few years ahead of their eruption. (Space Weather, https://doi.org/10.1029/2018SW002109, 2020)

—Sarah Stanley, Freelance Writer

Creating Data Tool Kits That Everyone Can Use

Mon, 05/11/2020 - 12:30

As Earth science and the technologies it uses evolve and improve, the data and services that support the science also change and become more complex, often spanning multiple disciplines. The ability to easily find and seamlessly access these data and services in an open and integrated environment is essential to facilitating interdisciplinary research and applications and to broadening data user communities.

The sheer amount of available data is growing rapidly as the science community adopts the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles [Wilkinson et al., 2016] and emerging technologies such as cloud computing. Even with recent advances in data archiving and services (e.g., more data sets and related information are available online with customized data services and multiple data access methods), accessing heterogeneous interdisciplinary data sets (e.g., those with nonuniform data types and formats) still poses challenges to users globally.

To address these challenges in Earth science interdisciplinary data services, we organized and led sessions entitled “Data and Information Services for Interdisciplinary Research and Applications in Earth Science” at AGU Fall Meetings 2018 and 2019; at both meetings, this was one of the largest of the Earth and Space Science Informatics sessions. International groups of participants presented data, tools, and services for Earth science interdisciplinary research and applications, as well as work on other topics related to big data, artificial intelligence (AI), machine learning (ML), and natural language processing.

Six Challenges

As a result of the presentations, discussions, and feedback from our AGU Fall Meeting sessions, we identified the following questions that address challenges in making Earth science data and data services more accessible and useful:

How can we make Earth science interdisciplinary data sets needed for a specific research project or application easier to find? How do we eliminate the need for the many special tools, some with steep learning curves, that are currently required to handle heterogeneous and interdisciplinary data sets? What data services can we provide in the cloud environment, where unprecedented access to data sets and data analytics are available? What data services can we provide to facilitate AI/ML activities? How can we collect metrics to help development and enhancement of data services and to benchmark the performance and societal impacts of a project or mission? How do we ensure the scientific reproducibility of Earth sciences research? Finding and Accessing the Data

Access websites for different data resources are often designed differently, and as a result, only those who are already familiar with the repositories can easily locate data sets and information.Data users typically consult various sources (e.g., the Internet, conference proceedings, colleagues, professors) to find where data are archived and distributed among many repositories around the world. However, access websites for different data resources are often designed differently, and as a result, only those who are already familiar with the repositories can easily locate data sets and information. Finding the right data and information for a specific research project or application is another challenge, especially for inexperienced data users who may not be familiar with data sets outside their own disciplines and for people searching across disciplines.

The variety of access website designs can impede data and information searches by users who are unfamiliar with specific repositories. For example, NASA’s Earth Observing System Data and Information System (EOSDIS) has 12 discipline-oriented Distributed Active Archive Centers (DAACs) that archive and distribute NASA Earth data sets from satellite missions and projects, each with its own unique web interface. For users doing interdisciplinary research that requires data from multiple DAACs, it can be difficult to become familiar with all of the interfaces.

One solution is to develop an integrated and uniform web interface for data access. At present, NASA EOSDIS is developing such an interface, called Earthdata, which serves as a gateway for all data sets and services at the 12 NASA DAACs. When the interface is finished, users will be able to search all NASA Earth science data, along with data services and information, in one place. Building this type of one-stop shop for accessing complex and heterogeneous data, services, and information is a major challenge in improving interdisciplinary research and applications.

Incorporating human expertise with artificial intelligence and machine learning technologies such as natural language processing may improve the user experience of finding data for a specific need.Another barrier to easy access is that discipline-oriented websites currently exist for their own special disciplinary requirements. To unify these different websites, an integrated data system must address both general and discipline-specific requirements. On a larger scale, Earth science data from various U.S. federal agencies, countries other than the United States, private companies, and citizen scientists must also be easily accessible in an integrated environment. Ideally, all these data would be accessible without the need to visit different websites, but making this a reality requires collaboration from domestic and international data scientists, developers, and stakeholders to address such issues as disciplinary vocabulary, data standards, and usability.

At present, many websites rely on sorting and filtering of search results. In satellite data services, for example, search suggestions, research subject, measurement, satellite source, and processing level are often used to narrow the list of search results. A user’s success in finding the data they need can vary significantly in such systems, depending on the web design, the user’s knowledge, and many other factors. Websites that focus on a single project or mission and contain only a few data sets can eliminate the need for sorting or filtering. For more comprehensive resources, inexperienced users often need human assistants or a help desk to interact with them, find out more about what they need, and provide recommendations for data products or services. Therefore, incorporating human expertise with AI/ML technologies such as natural language processing in the system may improve the user experience of finding data for a specific need.

Simplifying the Tool Kit

Because interdisciplinary data sets are complex, and their formatting and data structures are not uniform, multiple tools are needed to handle such data sets for research and applications. For example, more than 61 data tools are available at the 12 discipline-oriented NASA DAACs for search and order; data handling; subsetting and filtering; geolocation, reprojection, and mapping; and data visualization and analysis. It can be a daunting task for a user to learn all of these tools for interdisciplinary activities.

Heterogeneous data can also present challenges to users or stakeholders without access to complex data set processing capabilities. For many users, acquiring dedicated software, using multiple tools, and performing programming-based data analyses are not viable. The use of standards like uniform data formatting may address the problem of heterogeneous data often requiring many tools to handle. Data tools that integrate more data processing capabilities may also help in reducing the number of tools. Meanwhile, data repositories can go beyond their existing services (e.g., providing original data as they are) by offering data interoperability services to provide data that meet users’ research or application requirements with respect to data format, projection, model grid, and spatiotemporal resolution, for example.

Putting New Capabilities to Work

Cloud computing provides new opportunities to address issues related to the unprecedentedly large amount of data and data analytics available. Governmental and private organizations are putting significant efforts toward developing cloud-based data services. For example, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) plans to launch its popular online visualization and analysis tool Giovanni in the cloud, creating the potential to scale up and expand its current capabilities by, for example, including Earth science data sets from other NASA DAACs, improving performance, and providing new data analytics.

Best practices, including user-friendly features and services, should be carried over to the cloud environment.Best practices, including user-friendly features and services, should be carried over to the cloud environment. These practices can facilitate a smooth or seamless transition from on-premises data services to the cloud and ensure a satisfactory user experience in the cloud-based environment. One such initiative currently under development is the NASA EOSDIS Cumulus Project, a cloud-based framework for NASA EOSDIS data collections. This project is designed so that users will not notice any difference between the on-premises and cloud-based data services.

Cloud computing isn’t the only area in which new technologies are introducing significant changes. In recent years, the Earth science community, like in many other sectors and scientific fields, has experienced a surge in research and applications using AI/ML techniques. Identifying and adopting the features that data repositories can provide to facilitate AI/ML activities are pressing and challenging issues. For example, natural language processing-based data systems could simplify access for users who want only visualizations (e.g., images, maps), facts, or information. These systems handle the interactions between computers and humans using natural language—ordinary human speech in the form of voice or text rather than arcane computer commands. On the other hand, more advanced users expect data repositories to provide analysis-ready or customized data (e.g., training data) for AI/ML activities. Down the road, standard or customized AI/ML services—running AI algorithms such as deep learning or random forests, for example—can be integrated into data repositories, allowing users to conduct AI/ML activities without leaving the system. Cloud computing may be able to host such services in the future.

Measuring Performance and Impact

Data metrics are frequently used to measure user and system activities—data access and usage in research and applications, for example—that are related to the life cycle of a data set and play an important role in Earth science. For example, in the satellite community, data usage metrics are used to benchmark a mission’s or project’s success and its societal impacts.

One key challenge is to develop metric standards for different disciplines so that metrics are interoperable in interdisciplinary activities. Among their many applications, data metrics supply key information to satellite data service providers for designing new data services and improving existing ones. Satellite product developers rely on data metrics to understand how their products are used. Thus, collecting data metrics is an essential part of a satellite mission or project.

One key challenge is to develop metrics that accurately describe a wide range of data-related activities in research and applications. Another is to develop metric standards for different disciplines so that metrics are interoperable in interdisciplinary activities.

But Is It Reproducible?

Scientific reproducibility is a cornerstone of Earth science (and of all scientific fields). Providing trustworthy data and results is one of the most challenging and pressing issues in the science community. Reproducing Earth science research requires documentation of all elements in the life cycle, including data, algorithms, software, computing environment, and other factors.

Several research projects and workshops have focused on ways to improve reproducibility by, for example, collecting best practice guidelines—like the community guidelines for open and reproducible workflows that the geoscience research modeling community has worked to develop [Mullendore et al., 2020]. Earth science users are also increasingly using open-source software, open standards, and services such as Jupyter Notebook to exchange workflows. For interdisciplinary research and applications, the scope is much larger, requiring participation and collaboration from the entire Earth science community and from stakeholders (e.g., journal publishers). Major challenges include the development of standards for the framework and for interoperability.

Going Far, Together

There are many challenges to improving Earth interdisciplinary data services. Emerging technologies like cloud computing and AI/ML can potentially enable significant progress in all aspects of interdisciplinary data services. However, tackling the challenges will also depend on active participation and collaboration from all involved parties in the community. In the wake of AGU Fall Meeting 2019, we plan to continue our follow-up activities, which include a special journal issue to report current advances and address the challenges.


We thank all session participants of the past two AGU Fall Meetings. GES DISC is funded by NASA’s Science Mission Directorate. Vasco Mantas received funding from the European Union’s Horizon 2020 program under grant agreement GA 776026.

New Analysis Helps Manage Risks to Shipping in the Great Lakes

Mon, 05/11/2020 - 11:30

A new step has been taken in bringing financial dimensions into water resources decision making. In Meyer et al. [2020], authors from the Universities of North Carolina and Massachusetts have examined both financial and engineering responses to the risk of water level fluctuations for navigation in the Great Lakes. They show that two very different adaptation strategies—dredging waterways and insurance contracts—can be combined practically and analytically. This is a fascinating example, not least because fluctuations of water levels in the Great Lakes are still not entirely predictable, so the risks of low water levels in navigation channels need to be effectively hedged. The finance sector should be paying attention!

Citation: Meyer, E. S, Foster, B. T., Characklis, G. W., Brown, C., & Yates, A. J. [2020]. Integrating physical and financial approaches to manage environmental financial risk on the Great Lakes. Water Resources Research, 56, e2019WR024853. https://doi.org/10.1029/2019WR024853

—Jim Hall, Editor, Water Resources Research

Are We Seeing a New Ocean Starting to Form in Africa?

Fri, 05/08/2020 - 12:47

Standing next to a lava lake at the summit of a massive volcano, Christopher Moore, a Ph.D. candidate at the School of Earth and Environment at the University of Leeds in the United Kingdom, could see the red haze of lava flows a few kilometers away. This might seem like a rare sight, but at Ethiopia’s Erta Ale, it’s business as usual.

Are such behaviors the first signs of a tectonic transition? This question is part of what Moore has been studying at Erta Ale. The entire Afar region in eastern Africa finds itself in the middle of changes that could split the continent, forming a new ocean basin. The magmatism at Erta Ale might be offering signs of this switch by mimicking the characteristics of a mid-ocean ridge.

The East African Rift valley, the Red Sea, and the Gulf of Aden are clearly visible in this Landsat 8 image, taken on 8 November 2019. Credit: NASA/Erik Klemetti

However, there isn’t agreement about how close the Afar region is to this tectonic transition. The geophysical characteristics of magma storage at Erta Ale could point to the region’s conversion to an incipient oceanic spreading center, but the petrology of the erupting lava might be telling us that we aren’t there yet.

What we will be able to see standing on top of Erta Ale will change dramatically in 5 million, 50 million, or 100 million years. The question is whether Erta Ale and the Afar region will become a new ocean, or whether ongoing tectonic collisions to Africa’s north and east will prevent this transition from occurring.

The Complex Tectonics of Eastern Africa

Few places on Earth remind people of the surface of the Moon more than the Afar region. Pressed against the Red Sea, this dry and desolate section of eastern Africa is covered in lava formed from the rifting of the continent.

The Afar region is home to a triple junction at the boundaries of three tectonic plates: the Nubian, Somali, and Arabian. They all meet near Djibouti and Eritrea, forming a massive Y on the Earth’s surface. The Great Rift Valley opens to the south, reaching over 6,000 kilometers into the heart of Africa. The Red Sea Rift extends to the northwest until it meets the Sinai Peninsula. To the east stretches the Aden Ridge, an oceanic spreading ridge. All of these boundaries are spreading at rates of up to 1.5 centimeters per year.

This tectonic complexity means that Africa is a continent tearing itself apart. For 30 million years, part of eastern Africa, known as the Somali plate, has been peeling away from the rest of the continent. This has created the Great Rift Valley, which starts in Ethiopia and Eritrea and splits around the Kenya Dome until recombining in the Malawi Rift. On a map, you can trace the rifting continent by looking at the chain of lakes like Tanganyika and Nyasa (Malawi) that line the bottom of the Great Rift Valley.

At the same time, the Arabian plate has been moving away from Africa as the Red Sea Rift opens at a rate of around a centimeter per year. Someday the Arabian plate will stop moving as it collides with the Eurasian plate in what is now Iran, closing the Persian Gulf and becoming part of Eurasia.

The Afar region’s tectonic complexity has created some of the largest volcanoes on Earth. This volcanism is bimodal, meaning eruptions lie on the ends of the compositional spectrum. Vast lava flows of basalt intermingle with massive explosive eruptions of lava more silica rich. These volcanoes line the Great Rift Valley.

To the north, massive basaltic shield volcanoes like Erta Ale lie near the Red Sea. Traveling south, you run into Ethiopia’s massive Corbetti Caldera, one of the most potentially dangerous volcanoes on the planet. Farther into Africa, you find oddities like the carbonatite-spewing Ol Doinyo Lengai in Tanzania to the east and the Democratic Republic of the Congo’s massive twin volcanoes of Nyamuragira and Nyiragongo to the west. All of these volcanoes reveal the active rifting beneath eastern Africa.

What Drives a Continent to Split?

Why is this area such a hub for rifting and spreading? One explanation is that the Afar plume has been heating the region from below. This mantle plume prompted the African continent to begin to rise and split, creating rift valleys. Much like how the North Atlantic Ocean opened 80 million years ago, there appears to be a close connection between a large mantle plume and the creation of new continental rifts and, eventually, two passive (continental) margins separated by seafloor spreading at ocean ridges.

Extensional (divergent), collisional, and transform boundaries have been recognized for decades. How one boundary turns into another is less well understood.Geologists have long been able to identify different tectonic settings and plate boundaries. Extensional (divergent), collisional, and transform boundaries have been recognized for decades. How one boundary turns into another is less well understood. When does subduction start at a passive margin? What happens when a spreading center gets sucked into a subduction zone? When does the rifting of a continent finally create a new ocean basin? These questions are hard to answer because we have limited modern examples of these transitional phases of tectonics.

How can we recognize the point at which a rifting continent becomes a new ocean basin? All continental rifts are not the same, and some rifts fail, never producing true oceanic spreading. The Midcontinent Rift, for instance, was the site of an attempt to split North America about 1.1 billion years ago, but it failed. The mere observation of continental rifting does not mean that we are heading toward a new ocean.

The Afar region, at the nexus of tectonic plate boundaries, may be in the process of undergoing the transition from continental rift to oceanic spreading ridge. One way to approach the question of this transition is to examine the region’s crust. Instead of the 35-kilometer thickness that is typical for continental crust, the crust under Afar might be less than 20 kilometers thick. This includes layers of volcanic basalt that have spilled out over the area for millions of years.

Erta Ale: Afar’s Monster Volcano

Another way to approach the question of the possible transition from continental rift to oceanic spreading in Afar is to look at the region’s volcanoes. Erta Ale, in northwestern Ethiopia, is one of the most active volcanoes on Earth. The massive shield volcano stretches 50 kilometers across, is almost 100 kilometers long, and rises 600 meters from the Danakil Depression.

These maps show (left to right) the location of Erta Ale in the Afar region of eastern Africa and the thermal signature of its lava lakes, and the eruption from 2017 to the present. Abbreviations are EAVS, Erta Ale volcanic segment; TAVS, Tat Ale volcanic segment; AFVS, Afdera volcanic segment; ALVS, Alayta volcanic segment; DVS, Dabbahu volcanic segment; RSR, Red Sea Rift; GAR, Gulf of Aden Rift; and MER, Main Ethiopian Rift. Credit: Moore et al., 2019, https://doi.org/10.1029/2019GC008692

By most accounts, Erta Ale has been erupting constantly for over 50 years, producing lava flows that stretch far down its slopes. It is also a member of a very exclusive club of volcanoes that are home to active lava lakes. In fact, only two volcanoes in the past quarter century have hosted multiple lava lakes simultaneously: Erta Ale and Kīlauea. As of March 2020, there is one active lava lake in the summit caldera of Erta Ale, and it is potentially one of the longest-lived lava lakes in the world, first observed in 1906.

A drone captured this image of the Erta Ale lava lake in 2010. Credit: Michael Dalton-Smith, Digital Crossing

Erta Ale is not the easiest place at which to conduct fieldwork. Before 2010, the trek to the summit was long and hazardous. Today the summit area near the lava lake is accessible by a tarmac highway. This has meant that tourists can easily visit the lava lake, but not without risks from both the volcano and outside violence. In 2012 and 2017, tourists visiting Erta Ale were killed by gunmen, sending chills down the spines of many who visit the volcano regularly.

Analyzing Magma Storage

By pure coincidence, Erta Ale erupted 6 months into Christopher Moore’s Ph.D. research on magma storage in the East African Rift. “Science changes very quickly, so you follow the exciting things,” said Moore.

The eruption prompted a question among volcanologists: Is Erta Ale more like a rift volcano or an emergent mid-ocean ridge volcano? Moore and his collaborators have been attempting to answer just that question to understand how magma is stored under Erta Ale. In his 2019 paper in Geochemistry, Geophysics, Geosystems, Moore laid out data showing that Erta Ale shares characteristics of a fast spreading mid-ocean ridge like the East Pacific Rise (EPR). Magma is stored in shallow bodies just underneath the EPR, a characteristic typical for mid-ocean ridges. If the Afar region is an incipient oceanic spreading center, how would magma storage at Erta Ale compare?

Moore and his collaborators used Sentinel-1 synthetic aperture radar data to unravel how Erta Ale physically changed during the course of an eruption that began in January 2017. Using the Sentinel-1 data, Moore modeled the deformation at Erta Ale as shallow intrusions under the volcano’s summit and under the site of a fissure eruption on its southwestern slopes.

“The contraction that we see [at the summit] combined with opening of the new dike [on the slopes]…was pretty much symmetrical,” said Moore. This meant that magma was moving from the summit to the fissure and responding quickly to changes in the shallow magmatic system under the volcano.

Beyond this deformation, Moore and his collaborators were able to use the level of the lava lake at Erta Ale’s summit as a gauge for the pressure state in the magmatic system under the volcano. During periods prior to the fissure eruption, the level of the lava lake remained relatively constant according to Sentinel-1 data as well as to observations from tourists and scientists visiting the volcano. However, once the January 2017 eruption event started, the lava lake level dropped precipitously. This meant the level was very sensitive to the pressure state of the magma stored under the volcano, dropping as pressure was released during the new fissure eruption. The new eruption down the slopes of the volcano prompted the summit lava lake to drain rapidly.

On the basis of both the lava lake levels and the geophysical models, Moore and his colleagues think that there are stacks of shallow magma bodies under Erta Ale, all within kilometers of the surface. Thus, Erta Ale is much like the EPR, where shallow magma bodies lurk beneath the mid-ocean ridge.

Is It or Isn’t It?

Does this mean that Erta Ale is in that transition phase from a rift volcano to a mid-ocean ridge? Tyrone Rooney of the Department of Earth and Environmental Science at Michigan State University in East Lansing argues that it might be more complicated than that.

“If it looks like a duck and quacks like a duck, is it a duck? Maybe not,” said Rooney. There is no agreed-upon definition for what constitutes a transition from one tectonic setting to another in this situation. Rooney has studied the East African Rift for years and recently published a study in Lithos that tackles the evolution of magmatism in the area.

Rooney agrees that the Afar region is clearly in the advanced stages of continental rifting but doesn’t know whether the rifting is a direct precursor to oceanic spreading. The sources of melting under the Afar region caused by the Afar plume look to be different than one might expect at a newly forming mid-ocean ridge.

And even though the crust is thin in the Afar region, it is not clear whether the lithospheric mantle under the crust has thinned as well. On top of that, the rifting in the region of Erta Ale is propagating northward as opposed to southward, as would be expected if the Red Sea Rift were driving the extension. Even so, the Afar region still might be the closest current relative we have to a new oceanic spreading center.

The glowing lava lake at Erta Ale is illuminated with a spillover lava flow in 2010. Credit: Michael Dalton-Smith, Digital Crossing What Is the Transition?

Although the processes going on at Erta Ale and at a mid-ocean ridge look similar, they might be controlled by different tectonic processes.Right now, Moore agrees that Erta Ale is still in a transitional phase. The question becomes what the Afar region will look like in 5 million years. He said the transition to an oceanic spreading center will be recognizable when the region develops the typically dense, 7-kilometer-thick igneous oceanic crust. The presence of shallow magma bodies under the active parts of the rift will be another clue. A further sign will be the development of telltale “magnetic stripes” on both sides of the boundary, as lava erupts and captures the state of Earth’s magnetic field. In all cases, the switch to an oceanic spreading center will be gradual.

So far, it seems that Erta Ale is showing at least one of those signs: shallow magma storage. However, as Rooney has pointed out, we haven’t seen any development of true oceanic crust in the Afar region. All the petrologic evidence so far still points to the Afar plume as the source of the basalt erupting at Erta Ale. To him, this means that although the processes going on at Erta Ale and at a mid-ocean ridge look similar, they might be controlled by different tectonic processes.

Africa’s Future

The future of tectonics in the Afar region is unclear. It is far from agreed upon when, if ever, the region will become an oceanic spreading center or whether an ocean basin will form between the Somali and Nubian plates and how spreading in the Red Sea and the Gulf of Aden will progress. In one model, Christopher Scotese’s “future world” tectonic map suggests that 50 million years from now, the Red Sea and the Gulf of Aden will be gone as the Somali and Nubian plates slam into Arabia, suturing today’s three plates together.

The eruption at Erta Ale continues today. Moore’s research has shown that the volcano’s magmatic plumbing is a close continental analogue to the mid-ocean ridge magmatism in the East Pacific Rise. The question remains whether that similarity is a sign of things to come.

—Erik Klemetti (@eruptionsblog), Science Writer and Associate Professor of Geosciences, Denison University, Granville, Ohio

How Long Was Venus Habitable?

Fri, 05/08/2020 - 12:27

Earth and Venus are “sister worlds,” sharing a similar size, mass, and bulk composition. You wouldn’t want to visit modern-day Venus, though, with its atmosphere of carbon dioxide and nitrogen and surface temperatures hovering around 450°C. But our neighbor probably wasn’t always so inhospitable.

Deciphering what early Venus looked like isn’t easy—in part because the planet’s surface is relatively young, just 300–700 million years old—but indications from the Pioneer Venus mission suggest that its atmosphere once contained more water than it does today. Venus also might have hosted liquid water at its surface, as well as plate tectonics and a stable, temperate climate; some studies even indicate that Venus’s climate may have been more stable than early Earth’s, avoiding Earth’s icy snowball periods.

Theories abound about what led to Venus’s drastic transformation: A gradually warming Sun may have left the planet hot and desiccated after a short period of habitability, or a very early magma ocean and an atmosphere of carbon dioxide and steam could have given way to the planet’s current state nearly 4 billion years ago.

In a new study, though, Way and Del Genio provide evidence that a shallow water ocean and habitable conditions may have persisted on Venus for as long as 3 billion years, until volcanic large igneous provinces (LIPs) emerged simultaneously and ended the planet’s temperate period.

The team ran several simulations of Venus’s history using NASA’s ROCKE-3D (Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics) general circulation model to examine how variations in the planet’s rotation rate and surface water levels might have influenced its early climate. Assuming that Venus’s early atmosphere, like early Earth’s, was carbon rich and cool and that its rotation rate was slow, the team found that Venus’s climate could have been stable for most of the planet’s more than 4-billion-year history—a strike against the gradually warming Sun theory.

The authors believe that simultaneous eruptions of LIPs over the past few hundreds of millions of years could have led to a runaway greenhouse effect by releasing large amounts of carbon dioxide into the atmosphere. The resultant drying of the planet’s surface could have driven it into a new interior-surface dynamics regime, with newly exposed basalts—evident on Venus today—acting as an efficient oxygen sink.

In Earth’s past, LIPs have emerged sequentially in a random stochastic process, rather than simultaneously, which the authors note is “fortuitous for life as we know it today.” But not enough is known about Venus’s interior to speculate whether an uninhabitable end state is the inevitable product of internal processes on Venus-like planets or even on Earth for that matter. Researchers need more observations from Venus’s surface to better constrain its early history and further challenge the magma ocean theory.

Ultimately, a better understanding of Venus’s history will provide insights into both terrestrial processes and those of exoplanets, including whether the window of habitability is wider than currently thought. (Journal of Geophysical Research: Planets, https://doi.org/10.1029/2019JE006276, 2020)

—Kate Wheeling, Science Writer

This Week: We Thank Our Teachers

Fri, 05/08/2020 - 04:05

During my freshman year in college, I was assigned to Tom Burns’s intro astronomy class and, the next semester, to his freshman writing seminar. By my sophomore year, he was also my boss at Perkins Observatory, where I interned for the next 3 years. Mr. Burns, with his omnipresent rainbow suspenders, was downright theatrical with the crowds who visited Perkins every month, his enthusiastic love of science leaving grins on every face as they took turns looking through the telescope. He held poetry readings at Perkins (before he retired as director in 2018) and for decades wrote astronomy columns for the Columbus Dispatch and the Delaware Gazette. At Perkins, I learned how to build a small radio telescope and how to drive a riding lawnmower, but most important I learned from Mr. Burns the absolute joy that great science communication can bring and that we all have the power to mark out any strange path that leads to a career we really want. Thanks, Mr. Burns.

—Heather Goss, Editor in Chief


For as long as I can remember, words and language have delighted me, so it makes sense that the person who immediately comes to mind when I cast my mind back to my formative years is my favorite linguistics professor. After starting my freshman year with a 300-level Old English course, I was hooked. My next linguistics course was an introduction to the history of the English language with Lee Pederson, who is best known for his Linguistic Atlas of the Gulf States. I took every course I could with Dr. Pederson during the rest of my years at Emory. In these classes, I learned about syntax, complete with sentence diagramming (fun!); wonderful new words like diphthong and alveolar ridge; and the International Phonetic Alphabet, which I still use today in note taking or to remember how someone pronounces their name. I found things like the French influence on English following the Norman Conquest; the Great Vowel Shift; and the fact that Ye Olde should actually be pronounced “the old” because the Y was originally the voiced dental fricative Þ (thorn), later replaced because of similarities in the letterforms, to be absolutely fascinating. These things were all so cool that I just had to share them with friends over lunch in the student union. Dr. Pederson died in 2015, so I can’t thank him now, and I don’t know that I ever did in so many words all those years ago, but I certainly hope that he knew what his classes meant to me. In those classes, I experienced real joy at learning for learning’s sake.

—feɪθ ‘ɪʃi, Production Manager


I would like to thank my junior year English/senior year ethics teacher, Mrs. Candace Taylor. I had great teachers from preschool through college, but Mrs. Taylor has always been the one whom I remember the most. The last I heard, she was teaching at a local junior college (and I assume she has her Ph.D. by now), but that was my first instance of someone close to me furthering their education. To this day, it amazes me that this picture-perfect high school teacher was striving to go further in her own career, proving that women these days don’t need to settle, we are strong, and we can go wherever we put our minds to.

—Melissa Tribur, Production Specialist


I owe my love of science to my middle school science teacher, Robin Rybarczyk. She devised the most captivating experiments for us: fermenting yogurt, growing plant variants à la Mendel, and re-creating river meanders in a sand and clay tank. Ms. Rybarczyk absolutely spoiled us with so many hands-on experiments, and because of her, I learned the basics of science through experience rather than through a textbook. I can’t thank her enough for her patience, for answering our questions with questions of her own, and for that mischievous twinkle in her eye that made me want to learn everything there was to know about the natural world. Thank you, Ms. Rybarczyk, and to all the teachers who have made my life so rich!

—Jenessa Duncombe, Staff Writer


First off, thank you to all the dedicated and wonderful teachers I’ve had, from preschool through high school and in college and grad school. I’d like to especially thank Dr. Paul Tomascak, who introduced me to geoscience and encouraged me onto the path that led me to where I am today. As a recent college graduate some number of years ago (ahem, the dates aren’t important), I was casting about, applying to various jobs but generally uncertain of what I actually wanted to do. I loved science and had studied chemistry as an undergrad but wasn’t sure a life in the lab was for me. A year later, I enrolled in a summer class at the University of Maryland—Geology 100!—to see whether I’d enjoy a field of science that I’d largely overlooked up to that point. Almost immediately, I was hooked. Dr. Tomascak’s lessons were vibrant and easygoing, and his slides were full of engaging photos and images (not just text!). When I asked him how geoscience graduate programs might look at a former chemistry student with a single geology course under his belt as an applicant, he assured me I’d be a worthy candidate and gave me confidence to go forth and apply. For that, I’ll always owe him a debt of gratitude. Thank you!

—Timothy Oleson, Science Editor


I’ve been blessed with dozens of wonderful teachers who have helped me along my way, but I want to thank three of them in particular right now. First is my mom, Diane Star, who taught elementary school kids for 20-some years, including me and my sister. She taught me that it’s more important to measure your accomplishments against your past self than against the achievements of others. Second, my high school physics teacher, Pete Ogilvie, taught me that “physics is phun” even if you’re struggling with Millikan’s oil drop experiment. He encouraged my curiosity and supported my desire to study astronomy and planetary science in college. And third, my adviser in graduate school, Jason Wright, provided me endless support and encouragement when I decided that the researcher’s life wasn’t for me. He gave me room to explore until I found what I was looking for and, when I did, helped me develop the skills and tools I would need to make it happen. From the bottom of my heart, thank you!

—Kimberly Cartier, Staff Writer

Geoscience Societies Commit to Tackling Global Challenges

Thu, 05/07/2020 - 15:03

In the unprecedented circumstances surrounding the coronavirus disease 2019 (COVID-19) pandemic, the world is increasingly looking to the scientific community for clear information and solutions. In response, six of the world’s largest geoscience societies have issued a declaration to affirm the role of Earth and space science in addressing global challenges.

“Geoscience is dealing with several challenging global threats, and therefore, it is imperative that our community gets more unified and efficient than ever.”“We are now experiencing a global emergency,” said Alberto Montanari, president of the European Geosciences Union (EGU). “Geoscience is dealing with several challenging global threats, and therefore, it is imperative that our community gets more unified and efficient than ever.”

The pansociety declaration was delivered on 4 May, the opening day of the EGU General Assembly, which is taking place online.

“In recognition of the significance of international cooperation in science, technology and innovation, and particularly within the Earth, planetary and space science community, the European Geosciences Union, the American Geophysical Union, the Asia Oceania Geosciences Society, the Geological Society of America, the Japan Geoscience Union and The Geological Society of London declare our commitment to work together to support and promote all forms of geoscience research,” reads the declaration.

Accompanying the statement is a 10-point list of shared responsibilities. It details how geoscience research can support the United Nations’ Sustainable Development Goals while building public trust through transparent and ethical practices.

Throughout the pandemic, Earth and space science communities have helped to build understanding of the virus, from Earth observation to increased communication.

Emerging Links Between Air Quality and COVID-19

Studies about the connection between the spread of disease and air quality have used data from satellites such as NASA’s Terra and Aura missions and the European Space Agency’s (ESA) Sentinel-5P mission.

Nobody was surprised that air pollution, in the form of nitrogen dioxide in the troposphere, has been temporarily reduced in cities across the world as industry, transport, and other economic activities have ground to a halt.

Determining links between air pollution and the spread of COVID-19 cases is messier.

One study, led by Francesca Dominici at Harvard University, examined the link between COVID-19 mortality rates in the continental United States and long-term exposure to fine particulate matter. Dominici’s team found that even a tiny increase in the amount of PM2.5 (particulate matter with a diameter of 2.5 micrometers or less) appears to significantly raise the likelihood of dying from the disease.

A separate study, led by Edoardo Conticini at the University of Siena, linked poor air quality to the high death rates seen in the Italian regions of Lombardy and Emilia Romagna, both in the country’s industrial north.

Of course, the big caveat with these provisional studies is the high number of unknowns surrounding the novel coronavirus, such as the role of age and the causal mechanisms between exposure to pollution and the evolution of COVID-19 in patients, not to mention the complex web of confounding factors, such as population densities, lifestyles, and local public health responses, that also contribute to the development and outcome of the disease.

Shifting Focus of Earth Observation Data

Sandra Cauffman, acting director of NASA’s Earth Science Division, said that Earth observation data will soon play a bigger role in this research. NASA is planning to redirect some existing programs and provide an additional $2 million for satellite projects to address the environmental, economic, and societal impacts of the COVID-19 pandemic.

“In the end, what drives Earth observation is the societal benefit and how we can use [these] data for the global benefit.”NASA has also teamed up with ESA and the Japan Aerospace Exploration Agency to host a public hackathon scheduled for 30 and 31 May in which Earth observation data will be used to develop solutions related to the COVID-19 pandemic.

“In the end, what drives Earth observation is the societal benefit and how we can use [these] data for the global benefit,” said Cauffman.

To bolster efforts in Europe, the Copernicus Programme for Earth observation is providing additional information about air quality levels in 50 of the continent’s major cities. Meanwhile, scientists using grants from the European Research Council have been given the option to refocus their work toward coronavirus-related issues.

Sharing Geoscience Online

About 18,000 participants had been expected to attend the EGU General Assembly, one of Europe’s most important geoscience gatherings. In its place, EGU’s Sharing Geoscience Online is running throughout the week with livestreamed talks, short courses, and opportunities to interact with researchers.

Prominent geoscientists have used the platform to reflect on lessons learned from the COVID-19 pandemic.

Chris McEntee, former executive director and CEO of AGU, said that the community should think big and take inspiration from Winston Churchill’s response to World War II. “This is an opportune time for Earth and space science to be even more relevant and valuable to society, and to intersect more with society’s solutions in the future,” she said.

Jonathan Bamber, a glaciologist and previous president of EGU, is pleased that the status of science has been publicly elevated in recent weeks, as world leaders give regular pandemic updates flanked by medical and scientific experts. The key to maintaining the public’s trust, he believes, is to keep working together and promote open science.

“In times of emergency or crisis, cooperation is better than competition,” said Bamber. “Integrity and trust are vital to what we do, and part of developing that trust with our audience is being transparent about what we do.”

—James Dacey (@JamesDacey), Science Writer

El Sistema de Canales Preincaicos Usa Laderas Como Esponjas para Almacenar Agua

Thu, 05/07/2020 - 12:08

This is an authorized translation of an Eos articleEsta es una traducción al español autorizada de un artículo de Eos.

Lima, Perú, que se encuentra en el lado seco del Pacífico de la Cordillera de los Andes, es la segunda ciudad desértica más grande del mundo. (El Cairo, Egipto, es el más grande). Para soportar la estación seca, que dura de 7 a 9 meses en la región, los 10 millones de habitantes de Lima dependen casi por completo del agua recolectada de los Andes glaciares o transportada desde la exuberante selva amazónica hacia el este. Pero los glaciares se están derritiendo, y las presas y reservorios existentes, que contienen un total de 330 millones de metros cúbicos de agua, pueden calmar la sed de Lima sólo durante un año de sequía.

Un equipo de hidrólogos, ingenieros y científicos sociales esperan fortalecer la seguridad hídrica de Lima y otras ciudades peruanas a través del análisis de un sistema basado en la naturaleza que tiene 1,400 años de antigüedad, desarrollado por comunidades pre-incas de la montaña. La técnica utiliza un sistema de canales que desvía el agua de los arroyos a pequeños estanques o la extiende sobre laderas rocosas que actúan como esponjas naturales. Esto disminuye la velocidad del flujo de agua por las montañas, preservándola hasta la estación seca.

El análisis del equipo determinó que si el ya mencionado sistema de canales se ampliara a su capacidad máxima, podría desviar, infiltrar y recuperar hasta 100 millones de metros cúbicos de agua y aumentar el volumen de agua durante la estación seca de la región hasta en un 33%. El autor principal, Boris Ochoa-Tocachi, del Imperial College London, presentó los hallazgos del equipo en la reunión de otoño 2019 de la AGU en San Francisco.

Cuantificando el Beneficio de la Infraestructura Verde

Como la mayoría de las ciudades modernas, Lima cuenta con infraestructura gris, como embalses y presas, para el desvío y almacenamiento de agua. Sin embargo, la infraestructura gris por sí sola tiene sus inconvenientes. A menudo es costosa y difícil de implementar. También tiene un umbral estático, incapaz de adaptarse a las cambiantes condiciones ambientales.

“A veces pensamos que el conocimiento científico es más valioso que el conocimiento indígena y tradicional. Con esta investigación, tratamos de mostrar realmente cómo ambos pueden complementarse entre sí”.La infraestructura natural (verde) puede ser mucho más dinámica y rentable que la infraestructura gris. La infraestructura verde es una categoría amplia que puede incluir la plantación de pastos nativos para evitar la erosión y mantener la salud de los humedales para retener y filtrar el agua. De manera crucial, las comunidades pueden usarlo además de las presas y embalses ya existentes, lo que amplifica su efectividad y proporciona un amortiguador cuando se supera su umbral.

Para comprender las formas más efectivas de implementar infraestructura verde, los investigadores están examinando las técnicas ya utilizadas por las culturas indígenas de todo el mundo. Pero pocos estudios cuantifican los efectos hidrológicos de las intervenciones naturales como las utilizadas por las comunidades indígenas de las montañas andinas.

“A veces pensamos que el conocimiento científico es más valioso que el conocimiento indígena y tradicional”, dijo Ochoa-Tocachi. “Con esta investigación, tratamos de mostrar realmente cómo ambos pueden complementarse entre sí”.

Siguiendo la Corriente

Ochoa-Tocachi y su equipo realizaron talleres, visitas de campo y entrevistas con más de 100 miembros de un pueblo llamado Huamantanga en las tierras altas andinas cerca de Lima. El pueblo es uno de los pocos que aún mantienen los canales de ahorro de agua conocidos como amunas, y el equipo pudo localizar 11 canales de infiltración operacionales a través de un mapeo participativo.

“El conocimiento indígena de la gestión del agua es particularmente benéfico porque está estrechamente relacionado con el lugar donde se desarrolló, y se ha perfeccionado para responder muy bien a las condiciones locales.”Luego, inyectaron un tinte rojo en uno de los canales para seguir el progreso del agua a lo largo del tiempo. Muestras de manantiales locales hicieron ver que el agua del canal se retuvo bajo tierra durante un periodo de 2 semanas a 8 meses, lo que significa que al menos parte de ella se almacenó durante toda la temporada de sequía.

Una vez que habían cuantificado la capacidad de las amunas existentes, los investigadores modelaron cómo podría escalarse el sistema y aplicarlo a la cuenca del río Rímac, una de las principales fuentes de agua de Lima. Determinaron que el 35% del agua que fluye a través del río Rímac durante la estación húmeda podría desviarse de manera similar, aumentando el flujo del río durante la estación en un 33% al comienzo de la temporada de sequía. Estos efectos podrían aumentar la capacidad de la infraestructura gris actual para soportar las condiciones de sequía.

“La belleza del conocimiento indígena está en su especificidad”, dijo Kate Brauman, científica principal de la Iniciativa Global del Agua en el Instituto de Medio Ambiente de la Universidad de Minnesota, quien no participó en el estudio. “El conocimiento indígena de la gestión del agua es particularmente benéfico porque está estrechamente relacionado con el lugar donde se desarrolló, y se ha perfeccionado para responder muy bien a las condiciones locales.” .

A través de la utilización de amunas, los investigadores determinaron que el 35% del agua que fluye a lo largo del río Rímac durante la temporada húmeda puede ser desviada, incrementando el flujo del río en la temporada seca en un 33%. Crédito: Boris Ochoa-Tocachi

. Ochoa-Tocachi espera que los hallazgos de su equipo ayuden a informar las decisiones de política en la región a medida que se derriten los glaciares, en los que previamente dependían como amortiguador natural. “Si los glaciares se están contrayendo, la única forma de contrarrestar la pérdida de este amortiguador es mediante el uso de infraestructura natural”, dijo.

Perú ha adoptado la infraestructura verde en los últimos años, pero los proyectos que reciben financiamiento no siempre están respaldados por evidencia. Por ejemplo, un artículo de revisión reciente, en el que Ochoa-Tocachi es coautor, encontró que una política de plantar árboles no nativos en pastizales nativos de gran altitud en realidad está disminuyendo, en lugar de aumentar, la disponibilidad de agua. El próximo año, él y su equipo comenzarán una revisión de los beneficios de los pastos nativos para la seguridad hídrica y la prevención de la erosión para incentivar su preservación.

“El trabajo que están realizando el Dr. Ochoa-Tocachi y su equipo es crítico porque necesitamos evidencia más sólida de cuán efectiva es la infraestructura verde y bajo qué condiciones,” dijo Brauman.

—Rachel Fritts (@rachel_fritts), Student in the Graduate Program in Science Writing, Massachusetts Institute of Technology, Cambridge

This translation was made possible by a partnership with Planeteando. Esta traducción fue posible gracias a una asociación con Planeteando. Traducción de Luis David Coazozon García (@LuisDavidCG11) y edición de Bernardo Bastien (@Ber_bastien).

Who Are Your Collaborators?

Thu, 05/07/2020 - 12:06

Think about your scientific colleagues – those in your research team, those you write papers with, those in your immediate network. How do these groups form? Maybe they’re influenced by the hiring practices of your institution, the research projects you choose or are assigned to you, or the location of the meetings you attend. Are your collaborators people just like you? Do you actively seek out opportunities to make new connections and diversify your network? Could the demographics of your network affect your career and your collaborators’ careers?

We all want science to be more diverse and inclusive. We want people who are under-represented and historically excluded to have a greater presence and a louder voice, and to be free of underlying biases that slow this progress. But making that a reality takes awareness and effort. AGU is committed to greater diversity, equity, and inclusion in the Earth and space sciences and embodying that in our organization. We have devoted additional efforts in the past few years, best illustrated by AGU’s Ethics and Equity Center initiatives, appointment of an AGU Diversity and Inclusion Advisory Committee, and adoption of a new Diversity and Inclusion Strategic Plan. But how are we doing in practice?

Where did the data come from?

We analyzed how people interact as co-authors, looking for patterns by gender, age, and ethnicity.We analyzed how people interact as co-authors, looking for patterns by gender, age, and ethnicity. We have a treasure trove of information: about 25,000 annual abstracts for our annual meeting, 15,000 annual submissions to our journals, and close to 100,000 members or others who have provided gender, age, and ethnicity over the recent years.

Who is connected with whom? How are connections associated with successful publication and citation?Stripping out all personal identifying information, we looked at who is connected with whom, and how these connections are associated with successful publication and citation. Having age data is critical for separating out the historic decreased participation of women and minorities in the Earth and space sciences.

Our results were published recently in two articles. The first, Age, Gender, and International Author Networks in the Earth and Space Sciences: Implications for Addressing Implicit Bias [Hanson et al., 2020], used AGU Fall Meeting abstracts from 2014 to 2018, which provided 400,000 unique author-author connections and allowed us to construct co-author networks by age, gender, and country. The second, Association between Author Diversity and Acceptance Rates and Citations in Peer-reviewed Earth Science Manuscripts [Lerback et al., 2020], analyzed 91,000 submissions to AGU journals from 2012 to 2018, which included 440,000 authors. This data set was used to compare levels of diversity among groups of authors to acceptance and citation rates.

What did we find?

Men and women in all age cohorts tended to be most connected with those around the same age, the exception being those in their 20s.What did we discover about these author networks? In terms of the annual conference, we found that men and women in all age cohorts tended to be most connected with those around the same age, the exception being those in their 20s whose networks were weighted towards colleagues 10-20 years their senior. Women’s networks tended to include equal (or slightly higher) proportions of women within each age group, while men’s networks included fewer women.

Younger people had a higher ‘rate of insularity’ and women’s networks were generally more insular than those of men.Younger people had a higher ‘rate of insularity’— that is, the proportion of their collaborators from their own country. Older age cohorts tended to have more international networks. The rate of insularity was highest among scientists from the United States and Japan, and lowest among scientists from Switzerland, Netherlands, and Spain. With a few exceptions (Canada, UK, Switzerland) women’s networks were generally more insular than those of men.

And what did we discover about the scientists who have published articles in our journals? Looking specifically at papers with two to four authors (because large author teams are typically more diverse), we found that 32% of author teams were international, 10% were multi-gender, and 91% were multi-career stage teams.

Papers with internationally diverse author teams had higher acceptance and citation rates; gender diverse teams had higher acceptance rates but lower citation rates.Papers with internationally diverse author teams had higher acceptance and citation rates than single-nation team papers, while gender diverse teams had higher acceptance rates but lower citation rates than single-gender team papers.

Though the analysis of ethnic diversity only applies to U.S. authors (6% of the submissions in our data set), racially/ethnically diverse teams had lower acceptance rates and lower citations but the latter was not statistically significant.

What does this mean for particular cohorts?

Our findings about the characteristics of networks suggest that age-affinity bias coupled with gender bias could be a double-whammy for younger female scientists.Our findings about the characteristics of networks suggest that age-affinity bias (people interacting more with those from the same age cohort) coupled with gender bias (men interacting more with men than women) could be a double-whammy for younger female scientists who need to develop a strong network of collaborators to advance their research and careers. This is a concern as younger women make up a significant proportion of AGU’s membership.

A triple whammy is that women are often not equally placed to take advantage of opportunities to collaborate internationally compared to their male counterparts.

While gender and international diversity can positively impact science, there is still bias with regards to ethnic and racial diversity.Meanwhile, our findings about the characteristics of author teams show that gender and international diversity can positively impact science, but there is still bias with regards to ethnic and racial diversity, which has also been recently highlighted in other studies. This bias may be occurring at the time of peer review and/or prior to peer review as underrepresented minorities navigate and advance in their STEMM careers.

While the study was possible in the Earth and space sciences thanks to the great information provided by AGU members, these findings likely extend to other disciplines.

What next?

Analyzing this data set has been challenging and fascinating. It has given us a quantitative snapshot of how Earth and space scientists interact with one another through AGU’s annual meeting and publications program. This is vital as we seek to deliver our goals for diversity and inclusion.

Our data came from you and your behavior. The commitment to increasing diversity and inclusion in our science rests on us all.But our data came from you and your behavior; it was an analysis of your coauthors, borne out of your collaborations and networks. The commitment to increasing diversity and inclusion in our science rests on us all. Next time you reach out to someone to collaborate or provide input on hiring or lab assignments, ask yourself: Could we be more diverse? Whose voice is missing from this group? Could my research be enriched with a perspective from someone new?

—Paige Wooden (pwooden@agu.org; 0000-0001-5104-8440), Senior Program Manager, Publications Statistics, American Geophysical Union

Hardwood Forest Soils Are Sinks for Plant-Produced Volatiles

Thu, 05/07/2020 - 12:01

Biogenic volatile organic compounds (BVOCs) are carbon-containing molecules released into the air by plants. They act as signaling molecules between trees—in a kind of airborne chemical communication—and play important roles in larger climate processes by facilitating aerosol formation and ozone production. Forest soils can store BVOCs and influence the compounds’ exchange with the atmosphere, functions that are affected by variables that scientists are keen to understand, such as the types of trees present and associated fungi growing in the soil.

In a new study, Trowbridge et al. analyzed BVOCs in situ from two types of soil within a hardwood forest in south central Indiana. The first type was beneath trees that associate with arbuscular mycorrhizal fungi (AM), a type of symbiotic fungus that penetrates the cells of tree roots to form a network of nodes where sugar, gas, and nutrients are exchanged. The second type of soil was beneath trees that associate with ectomycorrhizal fungi (ECM), which form tiny exchange nets around plant roots but do not breach the root cells themselves. Scientists often find substantial differences in soil biogeochemistry between AM- and ECM-dominated forest stands: For example, AM-associated tree species drop litter that decays more rapidly and cycle nutrients faster than ECM-associated tree species.

Overall, the new analysis shows that both soil types studied work as net BVOC sinks during the growing season; however, other factors, like temperature and moisture, are critical to understanding the larger picture. ECM soils absorbed more BVOCs than AM soils, especially as temperatures warmed. ECM soils were also much more active when moisture levels were higher. Finally, ECM soils showed stronger seasonality, acting as sources of BVOCs before the growing season but then becoming strong sinks after leaf out. AM soils, on the other hand, were weak BVOC sinks year-round.

The scientists conclude that characterizing forest soil by tree-associated mycorrhizal associations may be a good first step in capturing landscape-scale variation in BVOC transport between the land and atmosphere. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2019JG005479, 2020)

—David Shultz, Freelance Writer

Explaining Cold and Fresh Southern Polar Ocean Surface Waters

Wed, 05/06/2020 - 15:30

Most of the global ocean surface has been warming in response to increased greenhouse gases concentrations. One notable exception is the ocean south of 50 degrees south which, from the early 1980s to the early 2010s, has become colder/fresher in the upper 100 meters and warmer below. Various hypotheses have been proposed to explain this trend, among them a) increased glacial meltwater input due to ice shelf thinning, and b) increased northward transport of cold waters in response to the observed poleward shift of the southern-hemisphere westerlies.

Haumann et al. [2020] propose a further hypothesis of increased northward transport of sea ice over that period. The team carried out a suite of numerical simulations using a regional ocean model to investigate the three hypotheses by separately increasing sea-ice fluxes, freshwater input from the Antarctic continent and ocean-atmosphere momentum input by winds.

The observational trends are best reproduced in the simulations with increased lateral sea-ice transport. The underlying process is elucidated, leading to freshening/cooling of the surface waters and warming of the subsurface layer. This warming has important climate implications because the heat trapped in the subsurface accounts for approximately 8 percent of the global ocean heat content increase over that time period.

Citation: Haumann, F.A., Gruber, N., & Münnich, M. [2020]. Sea-ice Induced Southern Ocean Subsurface Warming and Surface Cooling in a Warming Climate. AGU Advances, 1, e2019AV000132. https://doi.org/10.1029/2019AV000132

—Paola Rizzoli, Editor, AGU Advances

Shedding New Light on the Nitrogen Cycle in the Dark Ocean

Wed, 05/06/2020 - 12:20

Every year, the Mississippi River dumps around 1.4 million metric tons of nitrogen into the Gulf of Mexico, much of it runoff from agricultural fertilizer. This nitrogen can lead to algal blooms, which in turn deplete oxygen concentrations in the water, creating hypoxic dead zones. The nitrogen cycle is a phenomenon environmental scientists would really like to understand better.

“As humans, we do put a lot of reactive nitrogen compounds into the ocean, especially in coastal regions, by…river runoff,” said Katharina Kitzinger of the Max Planck Institute for Marine Microbiology in Bremen, Germany. “It’s really crucial to understand how microbes turn over this excess nitrogen that we put into the environment.”

Nitrification is a two-step part of the nitrogen cycle in which ammonia is converted into nitrate. Nitrification has been understood since the late 19th century to be conducted by an array of microbes that first oxidize ammonium into nitrite and then nitrite into nitrate.

“If our results can be extended to the rest of the ocean, no additional undiscovered [nitrite-oxidizing bacteria] are required to account for the global oceanic balance between ammonia and nitrite oxidation.”The details of this process have remained somewhat opaque until recently. It was only in 2005 that some of the key organisms in the first step of nitrification, ammonia-oxidizing archaea, were discovered. These archaea, belonging to the phylum Crenarchaeota, are among the most populous cell types in the oceans, and their ability to oxidize ammonia filled in one of the major blank spots in scientists’ understanding of the nitrogen cycle.

But this led to another mystery: Ammonia-oxidizing archaea are quite numerous, composing up to 40% of the oceanic microbe community, but the nitrite-oxidizing bacteria crucial to the second step in nitrification are 10 times less abundant.

“There’s hardly any nitrite in the oceans, which really suggests that any ammonia, which is oxidized to nitrite, must be balanced by the second group of organisms, which are converting the nitrite to nitrate,” Kitzinger said. “That was basically the huge discrepancy. We discovered these hugely abundant ammonia oxidizers, but the known nitrite oxidizers typically just make up” a small percentage of oceanic microbial life.

There were hypotheses to explain this discrepancy, according to Hannah Marchant, Kitzinger’s colleague in Bremen. Oxidizing nitrite yields less energy than oxidizing ammonium, so it’s possible that nitrite-oxidizing bacteria are simply slower growing. There could also be an undiscovered nitrite-oxidizing organism as abundant as the ammonia-oxidizing archaea, which would not be unprecedented given not only the recent discovery of the archaea themselves but also the 2015 discovery of new terrestrial nitrogen oxidizers, the comammox organisms.

Efficient, Fast-Growing Bacteria

But a new paper published in February in Nature Communications, of which Kitzinger and Marchant are first and second authors, respectively, suggests that there are no new nitrite oxidizers to be found in the oceans. Instead, existing nitrite-oxidizing bacteria are the key players and are unexpectedly vigorous ones at that. .

Ever wondered why marine #AOA are much more abundant than #Nitrospinae? Check out our new paper in @NatureComms https://t.co/OaIgt430FK@BiogeoMPIBremen, @DOME_Vienna, SDU, Georgia Tech pic.twitter.com/Cu7XwHzrMU

— Kathi Kitzinger (@KathiKitzinger) February 7, 2020

. Nitrite-oxidizing bacteria, they write, “are more energy efficient, and grow faster than [ammonia-oxidizing archaea],” at least within the Gulf of Mexico where the researchers based their study. “If our results can be extended to the rest of the ocean, no additional undiscovered [nitrite-oxidizing bacteria] are required to account for the global oceanic balance between ammonia and nitrite oxidation.”

The finding came as something of a surprise to Kitzinger and Marchant and their colleagues at the University of Vienna, the University of Southern Denmark, and the Georgia Institute of Technology. They had originally set out to the Gulf of Mexico to study archaea’s utilization of nitrogen compounds, particularly urea and cyanate. “But we also looked at the utilization of these compounds in nitrite oxidizers,” Kitzinger said, focusing on nitrite-oxidizing bacteria in the phylum Nitrospinae. Using isotopically labeled urea and cyanate to measure uptake by sampled microbes, as well as cell size and number, researchers were able to calculate cell growth rates.

“What we then saw was that the nitrite oxidizers actually incorporated a lot more of these compounds than the ammonia oxidizers” and were more energy efficient and faster growing than the archaea, Kitzinger said. In the most active water column samples, the bacteria increased fivefold over 24 hours.

A New Set of Bugs

But those findings did raise some questions for other researchers in the field.

Bess Ward is the William J. Sinclair Professor of Geosciences at the Princeton Environmental Institute in New Jersey and has been studying nitrogen her entire career. “They say that during a 24-hour incubation, some of the abundance is increased by five[fold] or sixfold, and that means a specific growth rate of several per day,” Ward said. The hypothesis struck her as strange because the measured growth rates of related Nitrospinae are significantly slower. “That actually stood out as a ‘Wow, so if that’s true, then they’ve got a new set of bugs.’”

Although researchers did see a maximum fivefold increase over 24 hours, the average across all their samples was a less extravagant 1.7.The measured growth rates also stood out to Maria Pachiadaki, a researcher at the Woods Hole Oceanographic Institution in Massachusetts whose work focuses on carbon fixation in the dark ocean. “Within 24 hours, it seems a bit unusual for a specific group to, you know, to increase like five[fold] or sixfold in abundance,” she said. It’s not something Pachiadaki believes casts doubts on Kitzinger and Marchant’s results overall, “but it’s something to keep in mind and try to see whether these incubations are outliers and need to be removed from the downstream analysis.”

But Kitzinger pointed out that her team measured growth rates two different ways—by counting cells in samples and by isotope uptake—and those rates matched, so “we don’t think there is a measurement artifact.” She also noted that although her team did see a maximum fivefold increase over 24 hours, the average across all their samples was a less extravagant 1.7.

“One also has to keep in mind that the shelf of the Gulf of Mexico is characterized by exceptionally high nutrient fluxes and ammonia and nitrite oxidation rates,” Kitzinger said. “We would expect that in the open ocean, where nitrification activity is much lower, Nitrospinae will also grow accordingly slower.”

Other unique properties of the Gulf could also be factors; Ward suggested that the relatively warm waters could be responsible for “these extravagant growth rates.”

Another question raised by Kitzinger and Marchant and their colleagues’ work awaits further research to resolve: If the nitrite-oxidizing bacteria are so efficient and vigorous, why are they so much less numerous in the oceans? The obvious answer, they said, would be high mortality and population turnover, but mortality due to what is not yet clear.

“At the moment, we don’t know whether that mortality is through grazing, that there’s something that’s just really eating them a lot, or whether they have a very high rate of viral infection,” Marchant said. “That is something that you would have to go back and do specifically designed studies to look at.”

Broader Implications

That answer could help researchers better appreciate the broader implications of this new understanding of nitrite-oxidizing bacteria, according to Pachiadaki. Her own research has focused on how bacteria and other microbes fix carbon in the dark ocean, where there are no photosynthesizing organisms. That work led Pachiadaki to realize she was missing a large group of organisms that must be contributing to dark carbon fixation and, eventually, to the conclusion that the missing organisms must be the nitrite oxidizers.

“If we can also verify that this carbon is also highly and actively grazed, then we also have the link of how this carbon, that is produced chemoautotrophically, moves to a higher trophic level,” she said. “[We can understand] how carbon is transferred and how carbon can sustain a food web there.”

“The oceans are still such an unknown in a lot of ways that we don’t really know their contribution to carbon fixation,” Marchant added. “If we don’t understand the basic fundamentals of how these microorganisms function, then it’s also very hard to predict what might happen in the future.”

That’s a thread that Pachiadaki, for one, is ready to pull. “I have actually emailed [Kitzinger] in order for us to get the carbon succession rate per cell,” she said. “I want to see how comparable it is with what I calculated. So this is an ongoing discussion.”

—Jon Kelvey (@JonKelvey), Science Writer

Unprecedented Clear Skies Drove Remarkable Melting in Greenland

Tue, 05/05/2020 - 12:07

It’s no surprise that warming temperatures are bad news for the Greenland Ice Sheet, a body of ice that’s 3 times the size of Texas. But temperature isn’t the only factor that controls how fast this monstrous ice sheet is melting.

In terms of melting, 2019 was one of the worst years for the Greenland Ice Sheet since measurements began in 1948.New research from scientists at Columbia University, NASA, and the University of Liège in Belgium shows that atmospheric conditions play an important role in driving major melting events.

In terms of melting, 2019 was one of the worst years for the Greenland Ice Sheet since measurements began in 1948. It had the second-largest amount of runoff and was the worst year ever in terms of the “surface mass balance negative anomaly.”

Surface mass balance takes into account how much mass is being added to the surface of the ice sheet (usually by accumulation of snow) compared to how much mass is being lost from the surface (because of melting, evaporation, and/or chunks of ice breaking off the edges).

Compared to the 1981–2010 average surface mass balance, in 2019 there was a surface mass loss anomaly of about 320 gigatons of ice—enough water to fill 128 million Olympic-sized swimming pools.

Lead author of the new study Marco Tedesco, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory, said that unusual atmospheric conditions in 2019 were important contributors to this record-breaking loss.

In much of Greenland, anticyclonic conditions were abnormally persistent. These conditions made it hard for clouds to form, so clear skies prevailed. “When you have clear skies,” Tedesco said, “you have more energy from the Sun reaching the ice surface, which means that you have an advancement of melting.”

Clear skies also meant that there was less snow; snowfall is an important contributor to surface mass balance of the ice sheet.

The persistent anticyclonic conditions, in which winds move in a clockwise direction in the Northern Hemisphere, also drew warm, moist air up from near the eastern United States and Canada into northern and western Greenland, actually promoting cloudy conditions. In this area of the ice sheet, however, the warm, wet clouds also increased melting.

Scientists think that these atmospheric conditions are linked to changes that have been observed in the jet stream.

“It seems that when you have a wavier jet stream, it almost works as a trapping mechanism for the anticyclonic conditions,” said Tedesco. “It creates these pockets of very highly persistent conditions.” Although we still don’t fully understand all of the mechanisms that affect the waviness of the jet stream, Tedesco said it’s likely related to climate change.

Greenland’s Impact on the Rest of the World

What happens in Greenland could have important implications for the rest of the planet: Tedesco said that the Greenland Ice Sheet is currently the largest single contributor to global sea level rise.

If the entire ice sheet melted, sea level would rise by 7 meters, which would be catastrophic for many coastal cities and for the hundreds of millions of people who live close to sea level.And the impact of continued melting could be devastating. Eric Rignot, a glaciologist at the University of California, Irvine, not involved in the study, said that an enormous amount of the Greenland Ice Sheet is at high risk of melting. If this high-risk ice melted, he said, it would be enough to raise sea levels by 3 meters, or nearly 10 feet. In an even more severe scenario, if the entire ice sheet melted, sea level would rise by 7 meters, or nearly 23 feet, which would be catastrophic for many coastal cities and for the hundreds of millions of people who live close to sea level.

Studies like the present one are important for building better models to understand how our future will be impacted. Tedesco said that current models could be underestimating future melting by a substantial amount.

“It is important to understand on what timescales this will take place because the process of rapid melt has started,” said Rignot.

“The two largest melt events in the past 500 years were recorded in 2012 and 2019,” he said. “This is telling us something. At least subjectively, large melt events are likely to become the norm, not isolated events occurring every so many centuries.”

—Hannah Thomasy (@HannahThomasy), Science Writer

Arctic Plankton Populations Vary by Season

Tue, 05/05/2020 - 12:03

As temperatures rise, sea ice melts, and the ocean’s chemistry undergoes significant changes in pH and salinity, predicting the downstream ecological effects is challenging, particularly in areas like the Arctic, where change is occurring quickly. Scientists often turn to planktonic species to glean insights into ecosystem health. These keystone species constitute the basis of the food web in the region and are especially sensitive to changes in the water.

In a new study, Ofstad et al. collected plankton samples in the spring and summer of 2016 from the Barents Sea, located north of Scandinavia and western Russia. The researchers focused on the Bjørnøyrenna crater area, which contains several methane seeps that release gas into the water, to survey how concentrations and species diversity of planktonic foraminifera (forams), as well as of the planktonic sea snail Limacina helicina, vary over time and in the presence of methane.

The results showed a clear seasonal signal, with populations of both living planktonic forams and Limacina helicina growing by an order of magnitude or more and increasing in size as spring progressed to summer. In summer, the foram community is more diverse, with the added presence of subtropical species.

To understand how methane in the water column might affect the forams—through their consumption of carbon from methanotrophic bacteria, for example—the scientists looked at isotopic ratios of carbon and oxygen in the organisms’ rigid calcium carbonate shells. Surprisingly, they found no evidence that the elevated methane levels in the water had a direct impact on the animals. That’s not to say the seeping methane has no effect at all: The researchers hypothesize that it could enhance primary production in the water column indirectly by, for example, carrying nutrients toward the ocean surface or increasing carbon dioxide levels in the water. Such fertilizing could have an effect on a regional scale, potentially drawing in increased numbers of other organisms—a topic that the team concludes should be studied in the future. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2019JG005387, 2020)

—David Shultz, Science Writer

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