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Asteroids, Greta Thunberg, and Other Things That Make an Impact

Fri, 01/24/2020 - 12:46

Earth’s Oldest Asteroid Impact Found in Australia. How old? About 2.2 billion years, according to scientists who studied isotope ratios in tiny mineral crystals pulled from ancient granite in Western Australia to date the event. The impact would’ve left a roughly 40-mile-wide crater, ejecting gobs of gas (think water vapor from an obliterated ice sheet) and debris into the atmosphere that might’ve possibly lifted Earth out of an ice age. This is a great short read about some fascinating (dare I say impactful?) research. (The writer is also familiar to Eos readers! See more of her good work here.—Ed.) —Timothy Oleson, Science Editor


Kids’ Climate Case “Reluctantly” Dismissed by Appeals Court. I’ve been watching this court case for years, and we’ve just had a new development. In 2015, nearly 2 dozen young people filed a lawsuit against the federal government, saying it hadn’t done enough to address climate change. The government’s inaction, the plaintiffs argue, threatens their constitutional right to life, liberty, and property. Last week, a federal appeals court dismissed the lawsuit “reluctantly,” saying that they needed to take their complaints elsewhere in the government. But the story isn’t over yet: The plaintiffs plan to petition for a review by the full Ninth Circuit in the coming month. For now, the wait continues. —Jenessa Duncombe, Staff Writer


10 Things Spitzer Taught Us About Exoplanets.

This artist’s concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets’ diameters, masses, and distances from their host star, as of February 2018. Credit: NASA/JPL-Caltech

This retrospective article from NASA lists some supercool discoveries made with the Spitzer Space Telescope that go far beyond its original mission. The spacecraft will be decommissioned next Thursday. —Faith Ishii, Production Manager


Greta Thunberg Pushes for Climate Action and Setting the Record Straight at the World Economic Forum.

I have never said anything like this, nor will I ever say it. It’s never too late to do as much as we can, every fraction of a degree matters. There are of course no magical “dates” for “saving the world”. I am only quoting the SR1,5 IPCC report on remaining CO2 budgets. https://t.co/zsvcYeo5tT

— Greta Thunberg (@GretaThunberg) January 21, 2020

Environmental activist Greta Thunberg provided powerful remarks about the need for climate action at the World Economic Forum in Davos, Switzerland, on 21 January. She also pushed back against an article posted by the World Economic Forum that reported in part that she had remarked that we have 8 years to save the world. Thunberg posted on Twitter, “I have never said anything like this, nor will I ever say it. It’s never too late to do as much as we can, every fraction of a degree matters. There are of course no magical ‘dates’ for ‘saving the world.’”

The World Economic Forum later posted a clarification that Thunberg had said at the forum that if we are going to hit the 1.5ºC target, our remaining emissions budget will be “gone within less than eight years.” —Randy Showstack, Staff Writer


Chilly with a Chance of Iguana.

Jan 21 – This isn’t something we usually forecast, but don’t be surprised if you see Iguanas falling from the trees tonight as lows drop into the 30s and 40s. Brrrr! #flwx #miami pic.twitter.com/rsbzNMgO01

— NWS Miami (@NWSMiami) January 21, 2020

Well, there’s a forecast you don’t see every day! When the temperatures in Miami, Fla., drop, the iguanas do too, according to the National Weather Service. My favorite part: “They may fall from trees, but they are not dead.” —Kimberly Cartier, Staff Writer


Might There Soon Be a Supernova Near Earth? Astronomers are monitoring a (relatively) sudden decrease in Betelgeuse’s brightness—impending supernova, or just business as usual? —Nancy McGuire, Contract Editor


Even Tardigrades Will Feel the Heat of Climate Change.

Tardigrades are microscopic aquatic animals. Credit: iStock.com/dottedhippo

Sure, they can survive at temperatures nearing absolute zero—one of my favorite concepts in all of science!—but hardy tardis may not be able to adapt to climate change. —Caryl-Sue, Managing Editor

Big Science, Small Package: The Joys of Writing Science for Kids

Fri, 01/24/2020 - 12:42

How do you explain solar physics to a 10-year-old? Very carefully.

I’ve been a professional writer for almost 2 decades, contributing to outlets like Science, Astronomy, and Eos, but by far the most difficult and specialized work I’ve done has been writing for young readers.

Credit: Houghton Mifflin Harcourt

Yet that’s the challenge I took on when I agreed to write Eclipse Chaser, the latest installment in Houghton Mifflin Harcourt’s award-winning series for young readers, Scientists in the Field, and the first book in the series to cover solar physics.

Eclipse Chaser tells the story of University of Hawai‘i solar physicist Shadia Habbal as she leads an expedition to Oregon to observe the 2017 North American total solar eclipse. Shadia has been studying eclipses since the 1990s, and her work has led to groundbreaking discoveries about the ionization of chemical elements at different temperatures in the solar corona—important insights into the coronal heating problem.

I’d previously written about Shadia, and although I found her work fascinating, I sometimes struggled to follow the details of her research myself or to describe it in language even other adults could understand. So although I knew that her work was important and she’d be a wonderful subject for a book, I also knew it would be difficult to share this complex science with kids.

Difficult—but worth it. As I’d gotten to know Shadia, I’d come to find her curiosity about the Sun infectious. What causes solar flares? How does the solar wind work? Why is the Sun’s atmosphere so much hotter than its surface? It intrigued me to think that this star could be so tantalizingly near, wield so much influence over our planet and our solar system, and yet still hold so many mysteries. I knew kids would be intrigued too. .

Shadia Habbal and a team of scientists traveled to a ranch in central Oregon to observe the 2017 total solar eclipse. Credit: Amanda Cowan

. Fortunately, I had some experience writing for young people and had worked with the wonderful editor Janet Raloff. Janet taught me that you don’t have to dumb science down to make it interesting and accessible to kids, but you do have to be thoughtful in the way you write about it. You might need to give more background information than you would if you were writing for an audience of scientists. Choose simple, concrete words over scientific jargon. Break up long-winded explanations into shorter sentences and paragraphs. Use metaphors and analogies to help kids visualize abstract ideas. And most important, tell a good story.

Fortunately, a total solar eclipse is a naturally compelling tale. The event itself is dramatic and spectacular, whereas the journey to observe one is a daunting, high-stakes scientific quest—offering a big payoff when things go right and a lot of opportunities for things to go wrong. Shadia and her team were full of stories about braving deserts, snowstorms, mosquito swarms, unhelpful border agents, and even polar bears to observe eclipses, only to have months or even years of work and preparation ruined by a passing cloud or last-minute dust storm.

I knew that if I could find a way to explain the science, the story would tell itself. .

Solar physicists Shadia Habbal and Enrico Landi discuss the Great American Eclipse. Credit: Amanda Cowan

I met with Shadia and a few other members of her team in Honolulu several times before the eclipse to talk about her plans and make sure I understood the scientific questions she would be investigating on this expedition. In August of 2017, I flew to Portland, Ore., to meet up with award-winning photographer Amanda Cowan and join Shadia and her team in the field, on a private ranch in the central part of the state. .

Many members of Habbal’s team traveled from Hawaii to study the eclipse. Credit: Amanda Cowan Habbal’s team brought their equipment (including laptops) to the remote Oregon location. Credit: Amanda Cowan

The team was incredibly generous in allowing us to pitch our tent alongside them, in inviting us to join them for a meal, and especially in making time to talk with us and letting us observe and photograph them as they got ready for the big event. We got to spend time not only with Shadia but also with many of her collaborators, including engineer Judd Johnson, physicist Adalbert Ding, mathematicians Miloslav Druckmüller and Pavel Štarha, solar physicist Enrico Landi, and many others.

On the morning of the eclipse, a haze of smoke from distant wildfires was cause for worry (and, I thought privately, dramatic tension!), but the skies soon cleared, and we were treated to a perfect, glorious totality. Shadia got the data she wanted, and I had an incredible story to tell—one with a happy ending.

—Ilima Loomis (ilima.loomis@gmail.com; @iloomis), Science Writer

Ulrich Christensen Receives 2019 Inge Lehmann Medal

Fri, 01/24/2020 - 12:34
Citation Ulrich Christensen

Uli Christensen is one of the unique individuals who have contributed to both domains of core and mantle and as such is a fitting recipient of the Lehmann Medal. It is rare for an individual to have had such a level of impact in both domains of geodynamo theory and geodynamics.

Early in his career, in joint work with David Yuen, Uli was the first to determine how pressure-induced phase changes influence mantle convection, demonstrating the viability of circulation across the mantle transition zone.

With Al Hofmann in 1994 he showed how gravitational segregation of ocean crust in the deep mantle resolves isotopic patterns observed in mantle-derived rocks.

Beginning in the late 1990s, Uli has produced a whole host of results that have clarified the behavior of numerical dynamo solutions; along the way he has shown great leadership in the geomagnetism community by instigating the first dynamo benchmark exercise, and he has engaged with observationalists for the common advancement of the subject.

Of the pivotal contributions made by Uli, I will highlight a select few. Uli is the originator of the mapping of regime boundaries for convective dynamos as a function of control parameters such as the Rayleigh, Ekman, and magnetic Prandtl numbers. Further work illuminated the regime boundary between dipolar and nondipolar dynamos, attributed to be controlled by the local Rossby number.

A lasting legacy is work with J. Aubert to create a comprehensive scaling theory for the geodynamo. This showed how the velocities, heat transfer, and magnetic field strengths all scale with the convective power. This analysis was groundbreaking when it was introduced 13 years ago and remains at the very forefront of modern ideas of the geodynamo. A tremendous application of these ideas was to explain the magnetic fields of planets and stars.

Uli has become a much-sought-after keynote speaker at conferences as a result of his prominence in the subject and broad knowledge of the area. It should be mentioned that Uli has freely shared his numerical dynamo database with others so that they can carry out their own analyses. This approach has won him many friends. He is a fitting recipient of AGU’s Lehmann Medal.

—Andy Jackson, ETH Zurich, Zurich, Switzerland



Thank you, Andy, for your kind words, and thank you to all who conspired to get me this prestigious medal. I was fortunate to be born at the right time. A law made by the German government when I was 17 provided generous support to students from low-income families, which allowed me to enter university. In the late 1970s, plate tectonics had come of age as an empirical theory, but its mechanism was not well understood. At the same time, computers became powerful enough for simulating complex nonlinear systems. Both fascinated me. My Ph.D. adviser was not an expert on either topic but was a very open-minded man. I was lucky that he gave me a free hand for working on the numerical simulation of mantle convection on my own. As a postdoc coming from the still somewhat parochial German geoscience community, Dave Yuen taught me, aside from a strong vocabulary in the English language, also the bold American way of tackling cutting-edge problems. Al Hofmann was so kind to host in his geochemistry department a guy who had not the vaguest idea about mantle isotopes. When I had mastered the fundamentals after 10 years, we published a paper together, marrying mantle convection with isotope modeling. In the late 1990s, I looked for something to give my research a new twist.  I was lucky again—realistic geodynamo modeling had just become practical. Gary Glatzmaier generously shared his code, and Peter Olson initiated me, coming from the very sticky world of mantle convection, to the airy physics of rotating magnetohydrodynamics.  I also profited a lot from working with other colleagues, postdocs, and students. From Neil Ribe I learned that nice numerical models are most useful when coupled with a scaling theory that allows us to extrapolate them to the real world.  Carsten Kutzner and I made the first steps toward understanding when a dynamo produces a dipole-dominated field. With Julien Aubert I tackled the question of what actually controls the strength of the magnetic field.  I tried to reach for the stars with astrophysicist Ansgar Reiners by showing that the magnetic fields of planets and those of rapidly rotating low-mass stars follow the same scaling rule.  It was a great pleasure to collaborate with all these people and many more. I owe them tremendously, and without them my scientific career would certainly not have culminated in receiving the Inge Lehmann Medal.

—Ulrich Christensen, Max Planck Institute for Solar System Research, Göttingen, Germany

Doomsday Clock Ticks Closer to Midnight

Thu, 01/23/2020 - 21:33

The symbolic doomsday clock moved closer to midnight than it has ever been, just 100 seconds away, because of the urgent threats of nuclear warfare and climate change, the Bulletin of the Atomic Scientists announced today, 23 January.

“Humanity continues to face two simultaneous existential dangers—nuclear war and climate change—that are compounded by a threat multiplier, cyber-enabled information warfare, that undercuts society’s ability to respond,” according to a statement released by the Bulletin to world leaders and the public. “The international security situation is dire, not just because these threats exist, but because world leaders have allowed the international political infrastructure for managing them to erode.”

“The current environment is profoundly unstable, and urgent action and immediate engagement is required by all,” Rachel Bronson, president and CEO of the Bulletin, said at a briefing in Washington, D.C. She and others urged world leaders to take bold actions to lower the risks of nuclear war and climate change.

The clock, which was created in 1947, had been set at 2 minutes before midnight for the past 2 years.

Bronson said that both nuclear and climate conditions are worsening. “Over the last two years, we have seen influential leaders denigrate and discard the most effective methods for addressing complex threats—international agreements with strong verification regimes—in favor of their own narrow interest and domestic political game,” she said.

“By undermining cooperative science and law-based approaches to managing the most urgent threats to humanity, leaders have helped to create a situation that will, if unaddressed, lead to catastrophe sooner rather than later,” Bronson added.

“Denial, Disregard, and Dangerous Brinksmanship”

At the briefing, former United Nations secretary general Ban Ki-moon said, “At a time when world leaders should be focused on the clear and present dangers of nuclear escalation and the climate emergency, climate crisis, we are instead witnessing denial, disregard, and dangerous brinksmanship.”

Other speakers also decried the growing global threats and inaction by world leaders.

“To test the limits of Earth’s habitable temperature is madness. It’s a madness akin to the nuclear madness that is again threatening the world.”“A few degrees might not sound like anything to worry about, much less like an emergency,” said Sivan Kartha, a member of the Bulletin’s science and security board and a senior scientist at the Stockholm Environmental Institute.

However, he added that if Earth warms by just a few degrees, it could be dire news for humanity. “We have no reason to be confident that such a world will remain hospitable to human civilization. To test the limits of Earth’s habitable temperature is madness. It’s a madness akin to the nuclear madness that is again threatening the world,” he said.

Robert Rosner, chair of the Bulletin’s science and security board, said that the clock’s closer approach to midnight “signals really bad news indeed.”

Rosner, a theoretical physicist on the faculty of the University of Chicago, said that a particular concern is “the undermining of the public’s ability to sort out what’s true from what’s patently false by information warfare, subverting our ability to arrive at a consensus on the solutions needed to achieve positive change.”

Rosner and others expressed hope that there is still time to reverse course. “Past experience has taught us even during the most dismal periods of the Cold War, we can as a people come together to address our challenges. It is now high time to do so again,” Rosner said.

“The World Needs to Wake Up”

“We are now 100 seconds to midnight, and the world needs to wake up,” said former president of Ireland Mary Robinson. She pointed to student activists and many others who are taking action on climate change as inspirational. “We need a change of mindset in politics, business, and civil society, one that enables us to keep temperature rises at or below 1.5 degrees Celsius while protecting the rights, dignity, and livelihoods of those affected by the shift to a carbon neutral economy. Not to do so will be a death sentence for humanity. And yet, world leaders continue to ignore the science, international climate summits fail to reach agreement, and investment in the exploration and exploitation of fossil fuels continues to increase.”

Former California governor Jerry Brown, executive chair of the Bulletin, added that there is still time to change course. “We’re not there yet. The world is not over. We have incredible opportunity to reverse the nuclear arms race, the carbon emissions and the headlong rush to ever more dangerous technology. It’s within human hands,” he said. “This is the moment if there ever was to wake up.”

“This is the moment if there ever was to wake up,” Brown added. “We can still pull back from the brink. But we have to do what we’re not doing. Whatever we’ve done to date is totally inadequate on nuclear, on climate, and on the other dangerous technologies, we have to find a way to do more. We have to change the design of how we’re behaving.”

—Randy Showstack (@RandyShowstack), Staff Writer

Dust Older Than the Sun Sheds Light on Galactic History

Thu, 01/23/2020 - 13:39

Hidden inside the famous Murchison meteorite are motes of stardust older than the Sun. A new analysis measured the ages of these stardust grains, which include the oldest solid material on Earth. The research also has revealed clues about the Milky Way’s past and how dust travels from star to star.

“With stardust, we can trace that material back to the time before the Sun.” “The most exciting part is to be able to study the star formation history of our galaxy with presolar minerals extracted from Murchison,” said lead researcher Philipp Heck, Pritzker Associate Curator at the Field Museum of Natural History in Chicago. “Stardust is the oldest material to reach Earth, and from it, we can learn about our parent stars, the origin of the carbon in our bodies, the origin of the oxygen we breathe,” he added in a statement. “With stardust, we can trace that material back to the time before the Sun.”

The Dust of Stars, Literally

How does stardust form, and how does it find its way into a meteorite bound for Earth? The process begins, as the name suggests, inside a star.

Stars at the asymptotic giant branch stage have four distinct layers. The innermost layer (blue) is a core of inert carbon and oxygen. The second layer (green) is helium fusing into carbon and oxygen. The third layer (yellow) is hydrogen fusing into helium. The outermost and coolest layer (red) is inert hydrogen. Credit: National Optical Astronomy Observatory/Association of Universities for Research in Astronomy/National Science Foundation

Just before it dies, a star whose mass is less than 10 times that of the Sun will have layers like an onion. The layers—made of carbon, oxygen, helium, and hydrogen—are either fusing new elements or collapsing under their own weight. At this stage of a star’s life, known as the asymptotic giant branch (AGB), the very top layers of the star’s atmosphere are cool enough for dust to condense. That is stardust.

During the last 100,000 years of its life, the AGB star will puff out its atmosphere to create a beautiful planetary nebula. Some of the stardust, propelled by the nebula’s expansion, will flow farther outward.

Stardust made up a tiny percentage of the interstellar soup that birthed our solar system. Less than 200 parts per million survived to be incorporated into the Sun, planets, comets, and asteroids.

And, in 1969, a 100-kilogram chunk of one carbonaceous chondrite bore some of that stardust to Murchison in Victoria, Australia.

As Old As Dust

Researchers ground down a small part of the meteorite into a fine powder and separated the stardust from the solar system dust by their chemical compositions. They then measured the ages of the microscopic particles by determining how long the grains had been exposed to high-energy galactic cosmic rays.

Exposure to high-energy cosmic rays changes the surfaces of dust grains traveling through the galaxy. Grains are more heavily coated with the isotopes helium-3 and neon-21 the longer they exist outside the solar system. (The Sun’s magnetic field shields the grains once they arrive.)

This speck of stardust, seen here in a scanning electron micrograph, condensed in the atmosphere of a dying star. It is silicon carbide and measures only 8 micrometers on its longest side. Credit: Janaína N. Ávila

About 60% of the newly discovered grains predate the solar system by only 300 million years. Adding the age of the Sun, the presolar age of the grains, and the time it takes a star to reach the AGB stage, this dating suggests that the stars that made these grains were born about 7 billion years ago.

Moreover, the team estimates that the stars that made these grains must have been between 2 and 3 times the mass of the Sun. Smaller stars wouldn’t have reached the AGB stage before the solar system formed, and the radiation from larger stars would have prevented the grains from growing as big as they did, the team argues.

Some of the grains show signs that they traveled the galaxy in large clusters, which is consistent with observations of objects like the Egg Nebula, said coauthor Jennika Greer, a graduate student researcher at the Field Museum. In addition, 8% of the grains dated in the study are more than a billion years older than the Sun. One grain is more than 3 billion years older than the Sun, which, at more than 7 billion years, makes it the oldest solid material on Earth.

These results were published in Proceedings of the National Academy of Sciences of the United States of America on 13 January.

Piecing Together Galactic History

Astronomers are still trying to figure out how often the Milky Way forms stars and whether the rate is constant or whether it fluctuates. Previous studies, some based on theory and some on observations, have pointed to a period of slightly enhanced star formation about 7 billion years ago.

“Our age distribution also supports a heterogeneous star formation rate, something that is supported in high-resolution models,” said Greer. “With presolar grains, we can analyze objects, like stars and supernovae, and events, like star formation, not normally accessible by laboratory studies.”

“I believe we will be able to resolve discrete events in our galaxy…much like that in zircon geochronology for solar system and terrestrial samples.” “An amazing aspect of this finding is that it is based on direct measurement of decay products, while generally the evidence…is based on indirect chronological methods, which are ultimately linked to a stellar model or statistical assumptions,” Helio Rocha-Pinto told The Guardian. “Yet they are the main tools we have for dating stars since we cannot take them to the laboratory.” Rocha-Pinto, an astronomer at Observatório do Valongo at the Federal University of Rio de Janeiro in Brazil, was not involved with this research.

This project analyzed 40 presolar grains from the meteorite. “We have already started separating more large, datable presolar grains from Murchison,” Heck said. The researchers hope that future grains will have ages that let them look further back in time.

“With more ages,” Greer added, “I believe we will be able to resolve discrete events in our galaxy in addition to our evidence for one period of increased star production, much like that in zircon geochronology for solar system and terrestrial samples.”

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

What Is Left in the Air After a Wildfire Depends on Exactly What Burned

Thu, 01/23/2020 - 13:24

Air quality is one of the biggest hazards associated with wildfires—for good reason.

As the air quality index approaches 300 (anything above which is considered hazardous), communities are forced to react. In 2018 in Portland, Ore., wildfires contributed to an air quality index of 157. Schoolchildren were forced to stay inside, outdoor activities were canceled, and local and state governments issued warnings to avoid breathing unfiltered air. In 2015, smoke from wildfires in Palangkaraya, Kalimantan (Indonesian Borneo), pushed the air quality index to 2,000. The air during that fire season caused 500,000 people to develop significant respiratory infections and was estimated to have caused the premature deaths of 100,000 people.

Wildfire emissions that influence air quality are dependent on the biomass feeding the fire. Biomass describes organic (mostly plant) material, including surface debris, the tree canopy, and belowground roots and peat.

All fires emit carbon dioxide, carbon monoxide, and particulate matter, including white (organic) carbon and black carbon. But largely because of biomass and other inputs, the exact makeup of smoke varies for every fire on Earth, from forest fires in the Pacific Northwest to peat fires in Southeast Asia to bushfires in Australia.

It’s All About Combustion

“All fires emit carbon dioxide because [fire is] a combustion process,” says Christine Wiedinmyer, an atmospheric chemistry modeler and associate director for science at the Cooperative Institute for Research in Environmental Sciences in Boulder, Colo. Combustion is a chemical reaction that produces heat, and wildfires can produce incomplete or complete combustion.

Fires can be smoldering, flaming, or both. They can burn at the very crown of a forest, jumping from treetop to treetop, or at the ground surface, igniting grass, shrubs, young trees, and ground debris of the understory. Some fires even burn belowground. Belowground fires can burn up to the surface, even reaching the tree canopy, or they can burn from the canopy down.

Each fire’s exact emissions cocktail is partially “determined by the way the fire is burning,” Wiedinmyer said. “If you have a flaming fire, you may have more complete combustion, more black smoke. If something is smoldering, you have less complete combustion, and that’s when you get the white organic carbon, white smoke, like [from] your charcoal grill.”

Big forest fires in Australia and California, which have superhigh burn intensities, often produce complete combustion, said Mark Cochrane, a professor at the University of Maryland Center for Environmental Science. Carbon dioxide and black carbon are primary emissions of these fires.

The temperature and intensity of the combustion processes also control chemical releases, explained Robert Yokelson, an atmospheric chemist at the University of Montana. Fire behavior, in general, affects the relative amount of flaming, glowing, distillation, and pyrolysis, and to some extent, pyrolysis temperatures have an impact on what volatile organic compounds are emitted. For example, he said, higher pyrolysis temperatures are needed to make benzene, a carcinogen sometimes released during wildfires that can affect a region’s air, soil, and water infrastructure.

As does, of course, the biomass, Wiedinmyer said.

Burning Biomass

Every type of biomass produces its own unique chemistry, and atmospheric chemists generally recognize six categories of biomass when evaluating a wildfire’s chemical signature: savanna (think Africa), tropical forest (think Amazon or Indonesia), temperate forest (think Sierra Nevada, Pacific Northwest, or northern Europe), boreal forest (think Siberia or Alaska), chaparral (think Southern California or Greece), and peatlands, which can be either tropical (Indonesia) or boreal (Siberia or far northern Canada). Of course, “the biomass of grasslands, shrublands, and forests is extremely variable, and mapped values are associated with a high degree of uncertainty,” according to new research from scientists working to incorporate such variability into new biomass mapping models.

For an example of how biomass influences wildfire emissions, consider the chemical signatures of emissions from a temperate forest, a tropical forest, and a savanna. Temperate forests with pines emit compounds such as pinene when they burn. These compounds can form into secondary organic aerosols, adding to the fire’s directly emitted black and organic carbon. They can also, to a much smaller extent, affect ozone chemistry. In the Amazon basin, biomass is dominated by the fresh, green canopy of the tropical forest. This type of biomass releases nitrogen-rich compounds when it burns, said Yokelson. Nitrogen is emitted in major quantities as ammonia, nitrous oxide, or nitrogen dioxide. All of these compounds are precursors for the secondary formation of particulate matter and ozone. In comparison, the brown grasses of African savannas or California hillsides emit far less nitrogen but are more likely to emit such compounds as black carbon.

Worldwide, savannas and tropical forests contribute the most burning-related emissions to the atmosphere. Savannas span 20% of Earth’s terrestrial surface but produce more than half of global mean fire emissions. In fact, from 1997 to 2016, savannas represented 62% of fire emissions, according to a paper published in 2018 in Nature Communications.

The burning of savanna grasslands produces significant amounts of black carbon—about 2 kilograms per hectare, Yokelson said. But “it’s not as simple as that,” he explained, because fires in forests consume more fuel than fires in savannas, so they can produce more emissions per unit area.

Mark Cochrane’s NASA-funded research team sampled burning peat in Jambi, Sumatra, in 2019. The bottom photo, taken in infrared, reveals locations of smoldering peat fires. Credit: Prof. Yulianto Sulisto Nugroho

Peatlands, meanwhile, represent just 3% of terrestrial land cover but hold a third of the world’s carbon, so when they burn, they can produce significant emissions, Yokelson and colleagues noted in a paper published in 2011 in Atmospheric Chemistry and Physics. And peatland emissions are vastly different from other types of biomass emissions.

Sumatra and Kalimantan, Indonesia, account for about half of the tropical peatlands on Earth. In these areas, Cochrane said, peat has a mean depth of 5.5 meters and can sometimes reach 10 meters deep. People regularly drain these peatlands and (illegally) set fires to clear the landscape, largely for oil palm plantations. The problem is, after those fires start, they are very difficult to put out. The aboveground tropical forests may burn rather quickly, but the peat underground can burn for months, often being extinguished only when the rainy season sets in, said Laura Kiely, a graduate student at the University of Leeds in the United Kingdom who led a study recently published in Atmospheric Chemistry and Physics on particulate emissions from Indonesian peat fires.

Peatlands have a vast fuel source, said Robert Field, a scientist at Columbia University in New York, and after they start burning, “they don’t stop pumping out smoke.”

That smoke is thick and white, filled with organic carbon, methane, carbon monoxide, and significant amounts of particulate matter 2.5 micrometers or smaller in size (PM2.5), Cochrane said. It hangs in the air above Indonesia and then travels regionally, reducing air quality as far away as in Malaysia and Singapore.

Sensing the Smoke

Cochrane and his team traveled to Indonesia in 2015 and again in 2019 to collect emissions data from peatlands directly. The air was so thick it felt like you could cut it with a knife, Cochrane said. The air quality index reached over 2,000 in September 2019.

To get the data they needed, researchers “took a lab to the field.”To get the data they needed, the researchers “took a lab to the field,” Cochrane said. They “ran around on coals”—one grad student’s shoes burned through—collecting air samples directly above peat fires.

For safety, they wore masks while in the thick of the smoke, but because the haze of PM2.5 blanketed the whole region, the masks “[didn’t] help much,” Cochrane said. “Even if we wear masks while standing over smoldering fires, we don’t wear them when farther away, or eating, or at night….When the smoke becomes ubiquitous, you basically cannot escape it. Near the fire looks bad, but much of the smoke is [of] larger particulates that aren’t as health-impacting and will settle out relatively soon. The haze that hangs over the region for weeks and months is made up of the smaller PM2.5 particulates that settle deep into your lungs.” Cochrane said it usually takes a few weeks after returning home for his lungs to clear out.

In the tropical peatlands of Sumatra, many areas of smoldering peat remain after the flames have passed. These smoldering peatlands release the majority of the fire’s gas and particulate

It is dangerous but important work, Kiely noted, because peatland emissions are not well accounted for in models.

When Kiely started trying to determine how Indonesian fires affect climate—by looking at models of fires and emissions—she found very little data. The model Wiedinmyer created, Fire Inventory from the National Center for Atmospheric Research (FINN), did not include peat. The other major emissions model, the Global Fire Emissions Database (GFED), does include peat, but the emissions factors are underestimated, Kiely said.

So Kiely started working with Wiedinmyer on creating a database of peatland emissions based on research by Yokelson, Cochrane, and others.

Some of these measurements are taken on foot, but more are taken from the air. Yokelson likes to fly through smoke at about 30–300 meters above the flames and then follow smoke plumes as far as he can to measure smoke evolution. During the 2013 Rim Fire in California, for instance, he and a large cohort of colleagues working with NASA followed the plume northward through Winnipeg, Manit., Canada.

The goal, Yokelson said, is to get as close as you can to the start of the fire to measure the emissions there and then to fly across the plume at various intervals downwind, say, every 15 kilometers or so. That way, he said, “you can see what the emissions are doing in the atmosphere—how they’re reacting. For example, is formaldehyde increasing or decreasing? What’s ozone doing? How much and how fast ozone forms is critical for both air quality and climate. What’s particulate matter doing—how far away is it traveling?”

Modeling the Movement

Chemists have made incredible advances, in the past 5 years especially, and “we [modelers] are behind—we’re just trying to catch up.”Chemists have made incredible advances, Wiedinmyer said, and “we [modelers] are behind—we’re just trying to catch up.”

“They [atmospheric chemists] have tools that can identify hundreds of compounds in biomass burning plumes. They say, ‘Here’s our list of 300 compounds that we can quantify, and we can give you emissions factors,’” she said. “We take that and try to apply it based on what we know about where and when fires are burning and what types of vegetation are burning and create a model.”

The stronger emissions data have enabled models to better match observations, Wiedinmyer said. Models show that it is not just types of biomass that affect emissions, but it is also the condition of the fuels, such as how wet or dry they are, and the amount of fuel that burns. “It’s all connected, all very complicated, and quite a challenge.”

In Canada, researchers like Jack Chen, a modeling scientist at Environment and Climate Change Canada (ECCC), are incorporating fire emissions into the air quality forecast system. They developed FireWork, a forest fire smoke model that relies on satellites to estimate wildfire emissions and uses forecast meteorology to simulate emissions dispersion, including everything from PM2.5 to ozone to nitrous oxides—any pollutants used in the air quality health index, Chen said. ECCC started using this system in 2016, and researchers have improved it every year since then by using better data from forest scientists, he said. The fire emissions models incorporate biomass density; fuel level burned; combustion efficiency; combustion type; combustion intensity (smoldering versus flaming); and even plume rise, using fire energy thermodynamics to determine plume injection heights, which help simulate how far emissions will travel, Chen said.

With FireWork version 2.0, which was used during the 2019 fire season, “we found that with better representation of fire emissions, we were able to better simulate the formation of PM2.5 and ozone from these fires,” Chen said. Depending on plume height, heat, intensity, changes in convection, and other factors, models have shown that PM2.5 can travel hundreds to thousands of kilometers away, and ozone can travel across continents, he said.

But there is still a lot of uncertainty surrounding emissions research, Chen noted, especially about feedback mechanisms and how fire emissions affect things like rainfall, ecosystems, and global warming.

A Clearer or Hazier Picture?

“How will fire change under a warming climate?” Field wondered. “What is the future of fire…and how do we predict high fire danger” early enough to make a difference?

In the past, for example, scientists knew that in an El Niño year, Indonesia would be drier than normal and fires likely would be severe. In 2019, however, an emerging climate pattern brought increased dryness to Indonesia and drought to Australia. This pattern contributed to severe fire danger in both countries. Scientists do not yet know how much of the climate pattern is related to global warming and how much it will change, Field said. “We’re hoping to untangle [that].”

Climate links to changing fire regimes are also important in California and the western United States, Field said. There, some research has suggested that vegetation types are changing in the wake of fires: The old vegetation, which may have adapted to less intense cyclical fires, is not coming back the same way. For instance, Yokelson said, forests may be converted to brush. Changes in vegetation can alter how emissions are offset by regrowth and can also alter fire return intervals, compromising an ecosystem’s ability to recover, he said.

Another question scientists are asking, Field said, is how individual or regional fires affect worldwide climate. In simple terms, black carbon (the type of emission common in grass fires) partially absorbs sunlight, causing warming; organic carbon (the type of emission common in peat fires) scatters sunlight, causing cooling. Carbon dioxide and other greenhouse gases increase temperatures; particulate matter can decrease temperatures.

It is easy to say that burning savannas release a lot of carbon dioxide and black carbon, so they warm the atmosphere, Yokelson said. But grass grows back quickly, so carbon dioxide is reabsorbed, halting the warming. And although burning peatland produces organic carbon and results seemingly in atmospheric cooling, there is no regrowth to offset the carbon dioxide produced—so there is actually net warming, he said. In the Amazon and Indonesia, deforestation causes significant emissions with little offset from biomass regrowth.

That said, when smoke fills the skies, temperatures drop locally, Yokelson said. In Montana, for example, he has seen a “forecast say, ‘Next week it’s going to be 100[°F],’ and then smoke from a fire fills the air, and temperatures only reach 80[°F].” Those effects are certainly felt most intensely close to a fire. Then, as the smoke spreads out downwind, a 20°F temperature drop becomes a 10°F drop, which becomes a 1°F drop even farther away, but covering a larger area.

But those local cooling effects are not the same as the greater climatic effects, he said. “Climate doesn’t care” whether it is smoky and cooler in Missoula or whether people cannot breathe in Portland or Kalimantan. Climate “cares” about the larger emissions volumes and reactions.

Radiative Results and Feedbacks

Some climate reactions involve changes in clouds and rainfall, Yokelson said. For example, recent research suggests that smoke particles create clouds with smaller droplets, which makes them less likely to rain. Smoke can also alter the thermal profile in the troposphere, affecting rainfall. But that is a “superactive area of research” with a lot left to learn, Field said.

Better integration of fire science and weather science would add clarity and help produce better forecasts of air quality, fires, and smoke.Another area of active research, Yokelson said, is examining how fires change albedo: Green forests absorb less heat than black, burned vegetation. Regreening takes time as well. How much that affects local or global climate is unknown.

Fire’s effects on snowpack and runoff are further issues scientists are studying, Yokelson said. When snow falls on forests with complete canopies, much of it is caught in the canopies and evaporates. When snow falls on burned areas, it falls straight to the ground, building up snowpack and causing more runoff. All of these “secondary” effects are significant, he said, but how significant, scientists cannot say.

Better integration of fire science and weather science would add clarity, Chen said, and help produce better forecasts of air quality, fires, and smoke.

The whole system is complicated, Wiedinmyer said, and there is “a lot we just don’t have a great grasp on yet.”

—Megan Sever (megansever@gneissediting.com; @MeganSever4), Science Writer

Eugenia Kalnay Receives 2019 Roger Revelle Medal

Thu, 01/23/2020 - 13:22
Citation Eugenia Kalnay

Professor Eugenia Kalnay is recognized for her exceptional contributions to numerical weather prediction; ensemble forecasting; data assimilation, including the production of global data sets for weather and climate research; and modeling the interactions between human society and the global environment.

While serving as director of the Environmental Modeling Center of the National Centers for Environmental Prediction (NCEP), she led development of their pioneering operational ensemble weather forecasting system, producing better forecasts with quantified uncertainties that are now part of everyday life. She also was lead author on the NCEP/National Center for Atmospheric Research 40-year reanalysis, the hugely influential effort to provide a consistent, accurate atmospheric history by using an up-to-date system to assimilate historical data, enabling important scientific advances in weather, climate, and environmental science.

With students and colleagues, she has worked vigorously to cross-fertilize nonlinear dynamics and meteorology, with a special focus on Kalman filters for data assimilation. Her textbook is a classic, and she has applied her techniques to such disparate problems as weather on Mars and carbon sources and sinks on Earth. She has especially sought to solve problems of societal relevance, helping develop the Human and Nature Dynamics (HANDY) model exploring interactions among economics, population dynamics, and environmental quality and showing how massive renewable energy installations could increase Saharan rainfall and vegetation.

Professor Kalnay is highly generous to students and colleagues. In 2015 she won the American Meteorological Society’s Joanne Simpson Mentorship Award “for effectively mentoring many early career scientists, with her unstinting generosity of time and attention in providing advice, encouragement, leadership, and inspiration.”

She was the first female Ph.D. recipient and first female faculty member in the Massachusetts Institute of Technology’s (MIT) Department of Meteorology; her thesis explored the circulation of the atmosphere of Venus. She joined the University of Maryland as department chair in 1999 and is now a Distinguished University Professor, their highest faculty honor, after service with NASA, the National Oceanic and Atmospheric Administration, and the University of Oklahoma. Professor Kalnay’s contributions have been recognized by numerous prestigious awards, including election to the U.S. National Academy of Engineering, American Academy of Arts and Sciences, Academia Europaea, and Argentine National Academy of Sciences.

For her broad and deep contributions to improved weather forecasting, Professor Eugenia Kalnay surely follows the tradition of Roger Revelle and thus is highly deserving of the medal in his honor.

—Richard B. Alley, Pennsylvania State University, University Park; John M. Wallace, University of Washington, Seattle; and Steven C. Wofsy, Harvard University, Cambridge, Mass.



I am very humbled to receive this medal and want to express my deep gratitude to Mike Wallace, Steve Wofsy, and Richard Alley for their kind and generous citation, and to my friend and mentor Fuqing Zhang, whose recent unexpected passing has been devastating to our field and our scientific community.

I am grateful to Argentina, and to Rolando García, the meteorologist dean of the College of Sciences of the University of Buenos Aires (UBA), where I received an extremely good, and completely free education that later made me feel MIT was rather easy.

I left UBA, like many hundreds of outstanding students and professors, after the military dictatorship attacked them and the dean in “the night of the long police batons.”  García recommended me to Jule Charney, my amazing adviser at MIT.

Since about 40% of science students at UBA were women, I expected the more “advanced” MIT would have 50%, so I was shocked to be the first woman in meteorology. At MIT, I met lifelong friends, like Inez Fung, J. Shukla, George Philander, and Mark Cane, whom I want to thank again for being my mentors.

I was blessed to work at NASA Goddard and to learn and practice global modeling and data assimilation. Shukla was head of “climate” and I was head of “weather,” and we both worked for Milt Halem, so I learned a lot about both climate and life.  Then I became director of NCEP’s Environmental Modeling Center, under Bill Bonner and Ron McPherson, who were very supportive when I wanted to change our methods. We introduced many improvements, like the first Variational Data Assimilation, and Ensemble Forecasting, and developed the first long Reanalysis, described in Kalnay et al., (BAMS, 1996) the most cited paper in all Geophysics.

After a decade at NCEP, my husband reminded me that power corrupts, so I asked McPherson if I could step down. I became a professor and the chair of the Department of Atmospheric and Oceanic Science at the University of Maryland, where I found what I really like to do: work with students and discover with them ways to improve models and data assimilation.  In Motesharrei et al. (Ecological Economics, 2014) we developed HANDY, a groundbreaking model that bidirectionally coupled the Earth and human systems showing that overconsumption of nature and large economic inequality both lead to societal collapse. More optimistically, in Li et al. (Science, 2018), we showed that large-scale solar and wind energy in the Sahara could provide ~4 times the energy used by humanity while substantially increasing precipitation and vegetation in both the Sahara and Sahel.

—Eugenia Kalnay, University of Maryland, College Park

Atmospheric Drag Alters Satellite Orbits

Thu, 01/23/2020 - 13:20

Earth’s thermosphere extends between about 90 and 600 kilometers above the planet’s surface and is where much human space activity occurs—the International Space Station usually orbits at an altitude of 400 kilometers, for example. Variations in atmospheric mass density subject satellites orbiting in the thermosphere to a drag force that decays satellite orbits and can even reduce their life spans. Imperfect modeling of this force leads to uncertainties in orbital predictions that create challenges for operators as they attempt to maintain orbits and avoid collisions among satellites.

Despite these concerns, the influences of variations in atmospheric density on orbiters remain poorly understood. Here He et al. use two models—the Drag Temperature Model and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model—to investigate effects in time and space of atmospheric density variations on a circular orbit at 400 kilometers altitude. The researchers also looked at two smaller-scale variations: the equatorial mass anomaly (EMA), which describes a local dip in density at the planet’s geomagnetic equator, and the midnight mass density maximum (MDM), which describes the tendency for atmospheric density to increase at the geographic equator after midnight.

Most notably, the authors show that the effects of atmospheric density are closely tied to the 11-year solar cycle. During periods of high solar activity, modeled orbits were altered by an order of magnitude more than during periods of low solar activity. For instance, when solar activity was high, the EMA could alter the daily orbit of a satellite by as much as 50 meters; when activity was low, the change was only 5 meters. The same pattern held true for variations at 8-hour, 12-hour, 1-day, 6-month, and 1-year timescales.

Across the timescales studied, semiannual variations had the largest effect on modeled orbits, altering them by as much as 800 meters during high solar activity, compared to 300 meters for annual variations. Semidiurnal variations were similarly larger than diurnal ones, with orbits changing during high solar activity by as much as 100 and 50 meters, respectively. The team found that the MDM had a stronger influence than the EMA, shifting orbits by a maximum of 150 meters during high solar activity.

As more orbiters—including multisatellite constellations—are sent into low Earth orbit in the coming years, results like these may become invaluable for planning avoidance maneuvers, estimating mission longevities, and predicting satellite reentries. (Space Weather, https://doi.org/10.1029/2019SW002336, 2019)

—David Shultz, Freelance Writer

Remote Landslide Puts Fraser River Salmon on Shaky Ground

Wed, 01/22/2020 - 12:28

On 23 June 2019, Fisheries and Oceans Canada was alerted to a landslide that tipped 1,800 metric tons of rock into a narrow gorge in French Bar Canyon on the Fraser River in British Columbia, creating a 5-meter waterfall. Throughout the summer, rock-scaling crews dangled hundreds of meters above the river to remove hazards such as boulders the size of cars.

Salmon are famously strong swimmers, but this new barrier created a ticking time bomb for thousands of fish migrating from the ocean to spawning grounds upriver.Wending its way more than 1,300 kilometers from the Rocky Mountains to the Pacific Ocean, the Fraser is a globally significant salmon-producing river. Critical to First Nations for food, social, and ceremonial needs, the five Pacific salmon species that breed in its tributary streams and lakes also support commercial and sport fisheries.

Salmon are famously strong swimmers, but this new barrier created a ticking time bomb for thousands of fish migrating from the ocean to spawning grounds upriver in late summer through autumn.

So a Unified Command incident management team was formed to resolve the emergency. It brought together geologists, biologists, engineers, and emergency personnel, plus leaders from British Columbia, the Canadian federal government, and First Nations.

Sam Fougère, senior engineering geologist with the consulting firm BGC Engineering Inc., attributed the landslide to fall rains followed by freezing and thawing, a process that loosened already fatigued, unstable rock.

In summer 2019, rock-scaling crews dangled hundreds of meters above the Fraser to remove hazards like boulders the size of cars. Credit: Province of British Columbia, CC BY-NC-ND 2.0

For salmon swimming upstream, submerged debris from the landslide raised the river bottom, “like a speed bump,” said Northwest Hydraulic Consultants’ hydrologist Barry Chilibeck.

Visual observations and lidar monitoring informed slope housekeeping by the scaling crew. At river level, Fougère directed rock manipulation to create salmon passageways using airbags and hydraulic rams, rolling over giant boulders and moving small ones to make pools, then using hand drills, explosives, and expanding grout to break them. As the crew removed boulders, “fish almost instantly would find a path through,” he said.

Salmon began arriving in July, before channels were cleared, so the team began transporting fish upstream by helicopter.

Gord Sterritt, a member of the Gitxsan Nation, an executive member of the Fraser River Aboriginal Fisheries Secretariat, and executive director of the Upper Fraser Fisheries Conservation Alliance, quickly saw the issue’s importance for First Nations, particularly the 23 Nations originating or residing in areas of the river above the landslide. He joined the team’s joint executive steering committee to oversee operations like beach seining and a fish wheel to capture salmon. It was an interesting learning experience, said Sterritt, “and I’m grateful for it, though not for the landslide itself.”

Some 60,000 fish were transported by helicopter, with another 245,000 getting through manipulated rock channels, explained salmon biologist Scott Hinch of the University of British Columbia. Some fish were radio-tagged to follow their fates.

“Potentially Catastrophic” Barrier Remains Submerged debris from a landslide on the Fraser created a “speed bump” for migratory salmon. Credit: Province of British Columbia, CC BY-NC-ND 2.0

The helicoptering of fish was not as successful as scientists and engineers had hoped. Many of the fish captured and put in transport devices “had been milling about for some time, and there’s a lot of stress on these fish already at the barrier,” Hinch said. Capture and transport added more.

One of the stocks most profoundly affected was the endangered population of early Stuart sockeye, so named for their early migration. According to hydroacoustic detection, about 26,000 early Stuarts entered the Fraser. They arrived at the blockage before passageways were cleared, so “only 89 spawners got to spawning streams,” Hinch said. Many streams had no arriving spawners at all. And of another 177 early Stuarts transported to a fish hatchery, researchers could spawn eggs from only 17 mature females.

The 2020 salmon migration is fewer than 5 months away, and the barrier could be “potentially catastrophic.”For now, salmon migration is over, but much of the blockage remains. The 2020 salmon migration, beginning with fish that migrate in spring, is fewer than 5 months away, and the barrier could be “potentially catastrophic,” said Hinch. The Canadian government is contracting out rock work over the winter.

Environmental scientist Jeremy Venditti of Simon Fraser University in British Columbia has been studying the geomorphology of the Fraser River since 2009. He has created an atlas of its 42 rock canyons, including French Bar. “What happens is, the canyon walls get undercut, and that removes the supporting rock underneath,” he explained. “Then everything on top slides into the canyon.”

Venditti’s 2019 survey at French Bar was canceled, as his boat operator was co-opted for the salmon rescue effort. But curious to pinpoint when the slide occurred, Venditti used satellite imagery to study the event, narrowing it down to 1 November 2018—meaning the remote landslide went undetected for nearly 8 months.

Given what’s at stake and the myriad of other stressors threatening salmon, is monitoring the river to predict and detect landslides a possibility?

Venditti thinks so. “This kind of thing is a routine occurrence in geological time,” he said, so “let’s try to predict where it might happen again.”

—Lesley Evans Ogden (lesley@oggies.net; @ljevanso), Science Writer

Scientific Meetings for All

Wed, 01/22/2020 - 12:24

Meetings and workshops are where scientists exchange ideas, foster collaboration, and reconnect with colleagues. Even as virtual interactions become commonplace, gathering in physical locations is still essential for building relationships and trust, being exposed to new ideas, and bridging perspectives on challenging problems. However, not all scientists have the opportunity to fully contribute at scientific meetings, and their attendance doesn’t guarantee that their ideas are heard or valued.

As awareness of inclusiveness issues grows, our community is actively developing and successfully providing resources for inclusive scientific meeting planning.Some members of our scientific community are left out because of barriers they encounter [National Science Board, 2015]. Attendees with mobility, sight, or hearing limitations may lack accessibility to meeting venues or facilities. Attendees with families may lack childcare or care for other family members who require it. Other attendees may lack safe bathroom spaces where their choice of which bathroom to use is not questioned or challenged and where they can summon help if necessary. Still others are targets of harassment and assault. These issues have led some to avoid networking events at conferences or not to attend conferences altogether, at significant cost to their careers [National Academies of Sciences, Engineering, and Medicine, 2018].

The scientific challenges and opportunities facing the scientific community demand novel approaches and ideas that will only come from a diverse, engaged scientific workforce. As awareness of inclusiveness issues grows, our community is actively developing and successfully providing resources for inclusive scientific meeting planning. It is time for scientists to commit to implementing these lessons to ensure that scientific understanding advances and continues to be applied for the benefit of all of society.

Developing Guidelines for Inclusive Meetings

Two meetings, including a workshop series and a conference, illustrate some of the ways that conference organizers can intentionally increase access to attendance and participation.

In May 2018, the Aspen Global Change Institute (AGCI) partnered with the Earth Science Women’s Network (ESWN) and 500 Women Scientists (500WS) to identify concrete ways to advance diversity, equity, and inclusion (DEI) in science workshops, including the workshop series hosted by AGCI. Four of the authors of this article were part of a group of 22 individuals with expertise in diversity and inclusion in science that met to identify specific actions that could be implemented in workshop planning, execution, and follow-on activities. Recommendations from this meeting were synthesized in “Inclusive Scientific Meetings: Where to Start,” published on ESWN’s and 500WS’s websites.

AGCI implemented these guidelines during its 2019 workshop season (May–September). For 30 years, AGCI’s interdisciplinary workshop series has advanced understanding of global change topics such as food system impacts of climate change, energy decarbonization pathways, climate modeling, and land use impacts on the Earth system. Each weeklong workshop creates opportunities for scientists to learn, ideate, and initiate new approaches to global change challenges. New protocols implemented in many aspects of the AGCI workshops dealt with the selection of topics, leadership, and participants, as well as registration, workshop environment, and program evaluation.

Meanwhile, another committee (which included several of the other authors of this article) was planning the conference (held 2–4 April 2019 in Boulder, Colo.) that initiated the Environmental Data Science Inclusion Network (EDSIN), supported by the National Science Foundation’s program Inclusion across the Nation of Communities of Learners of Underrepresented Discoverers in Engineering and Science (NSF INCLUDES). Broadening participation in science, technology, engineering, and mathematics is a core tenet of the NSF INCLUDES program, so hosting an inclusive event was a priority for the committee. Committee members sought suggestions from colleagues and also pulled best practices from online sources. They paid particular attention to ensuring that participants drove the conversation according to their expertise. The resulting conference plan adopted an unconference format that allowed researchers, practitioners, evaluators, and employers to set an agenda to examine DEI across the environmental and data science fields.

Putting the Plans to Work

Research shows that individuals who are already underrepresented in their fields often also experience underrepresentation in front of the podium at conferences.The AGCI workshops and EDSIN conference were learning opportunities for implementing inclusive practices at scientific meetings. Research shows that individuals who are already underrepresented in their fields often also experience underrepresentation in front of the podium at conferences. So a critical first step was the commitment of the organizing committees to ensure diverse representation among both attendees and presenters.

Conveners invited experts who would bring different perspectives, including those who were involved in diversity-focused professional societies or were from minority-serving institutions. AGCI required cochairs to cite how each potential participant’s expertise and background met the needs of the workshop and encouraged organizers to use resources such as 500 Women Scientists’ Request a Woman Scientist database. The EDSIN organizing committee sent invitations to 113 potential participants. They also tailored messages to different listservs and identified social media handles and hashtags to solicit participants beyond the committee’s existing networks. Final selection was based on independent reviews using a rubric aligned with conference goals.

Both organizations explicitly offered additional support to increase the accessibility of their events. Attendee registration forms requested information on access requests, dietary needs, and other accommodations. AGCI covered travel, hotel, and registration costs for all participants, and they offered stipends to those for whom caretaking responsibilities might have been a barrier to participation. EDSIN covered costs of travel, hotel, and registration for all attendees requesting support. They also prioritized identifying an accessible venue with inclusive amenities such as gender-neutral restrooms, and they reserved a quiet reflection space for anyone needing a break during the event. EDSIN also offered closed-captioned livestreaming and a Twitter backchannel so interested individuals who could not attend in person were still able to participate.

Starting meetings with calls to inclusivity underscores that every individual in the room comes with unique and valuable experience and expertise that are key in advancing solutions to the topic at hand. Credit: Eliott Foust, National Center for Atmospheric Research

AGCI and EDSIN both started their gatherings with calls to inclusivity. At the outset of each workshop, AGCI staff underscored that every individual in the room came with unique and valuable experience and expertise that were key in advancing solutions to the topic at hand. AGCI introduced workshop-specific methods—participants raising their name tents and waiting to be called upon by session moderators, for example—for engaging in discussion to ensure that everyone had an opportunity to be heard. Further, AGCI’s code of conduct was printed on cards that were inserted into each participant’s name tag sleeve for easy access. The card included instructions for how to report violations to the designated staff person.

At the EDSIN conference, a code of conduct was made available online and at the event, and it was verbally presented at the beginning of the conference. Participants were encouraged to follow the guidelines and to report any inappropriate behavior.

Progress and Challenges

The journey toward inclusion is iterative, and each meeting presents the potential for new challenges and lessons learned.The journey toward inclusion is iterative, and each meeting presents the potential for new challenges and lessons learned. These challenges often involve funding, logistics, and issues related to divergent points of view.

During postconference reviews, it became apparent that budgeting remains a challenge for both organizations. AGCI encountered obstacles securing funding to support workshops proposed and led by early-career scientists, whereas more established and senior scientists were typically better connected and more able to communicate workshop ideas with the program managers who allocate funding. However, early-career participants are also more likely to be from underrepresented groups, which provides additional motivation for the extra effort to promote these scientists’ ideas in the workshop discourse.

During a postconference committee meeting, EDSIN conference planners noted that budgeting for resources to improve accessibility and inclusion is critical. Organizers need to account for access requests so they can provide accommodations such as sign language interpreters, Braille translation, and speaker fees. Hiring professional facilitators can be expensive, but they can help maximize progress during challenging discussions. Facilitators can also help avoid the pitfalls of poorly led discussions, which can potentially cause more harm than good in building support for broader participation and inclusivity in workshops.

Not all challenges relate to money, however. For example, a land acknowledgment is considered an inclusive practice for acknowledging the history of Indigenous peoples and the impact of colonization. However, there are many differing opinions on the practice, including when it is appropriate and who should be engaged in developing and giving the acknowledgement. At EDSIN, these challenges were brought to light when the conference chair (a white woman) delivered a land acknowledgement that was received in different ways by attendees, including members of the Indigenous community. Every event will have to work with local Indigenous populations to determine the best approach for their venue and to ensure the acknowledgement achieves its intended purpose.

Other challenges included the additional time needed to search for diverse attendees outside the organizers’ personal networks, mitigating power dynamics between early-career and more senior participants, and the unwillingness of presenters to make their materials available to workshop organizers in advance so that these materials could be adjusted for accessibility.

Despite these challenges, both AGCI and EDSIN had positive outcomes in their meetings. AGCI averaged 36% female participants in their 2019 series of workshops, up from 30% in 2018 and 12% at the series outset in 1990. One of their four 2019 workshops achieved a 50:50 balance between attendees who identified as male and those who identified as female—only the second time this has occurred in AGCI workshop history. An average of 34% of participants were early career in the 2019 series, rising from 22% in 2016–2017 and 27% in 2018. Numerous participants gave informal verbal and formal written feedback, commenting that the workshops they attended were the most inclusive they had experienced. Many also mentioned feeling more comfortable and included as a result of the opening inclusivity presentation made by AGCI leadership.

EDSIN received 260 total applications to attend its conference, which resulted in an at-capacity event with 104 in-person attendees and 68 unique livestream viewers. EDSIN attendees represented 15 minority-serving institutions and included 21 people who self-identified as a person of color and 7 people who self-identified as having a disability. Of 82 respondents to a postconference evaluation, 93% indicated that participation was worth their time, and 85% indicated that their contributions to discussions were heard and valued.

What Scientists Can Do

Scientists must actively commit to holding ourselves, one another, and our organizations accountable.Scientists have an opportunity and an obligation to be change agents in their communities, but we must actively commit to holding ourselves, one another, and our organizations accountable. At an individual level, this commitment can mean advocating for inclusive practices in lab group meetings, department retreats, field team meetings, and other scientific endeavors. Panelists invited to speak at conferences can ask who else was invited and request a more diverse group if needed. Meeting organizers and session chairs can adopt inclusive practices and document methods and outcomes with conference proceedings and workshop reports.

At an institutional level, we as a community can demand higher standards regarding inclusive practices at our research institutions, companies, colleges and universities, and professional societies. In many organizations, such standards have already been codified, as in the case of AGU’s Diversity and Inclusion Strategic Plan, although it is incumbent on individuals to help hold these organizations accountable to their own stated goals. By sharing this guidance, specific how-to suggestions, and experiences implementing recommendations during recent meetings, we hope to empower scientists to make significant progress toward more inclusive meetings and to broaden participation in the scientific community.


We thank the Aspen Global Change Institute, Being the “Change” in Global Change Science workshop attendees, and co-organizers from the Earth Science Women’s Network and 500 Women Scientists. The EDSIN conference is based upon work supported by the National Science Foundation under grant 1812997. We also thank the 104 conference attendees whose contributions laid the foundation for this work. This material is also based upon work supported by the National Science Foundation under grants for QUBES DUE awards 1446258, 1446269, and 1446284 and DBI 1346584. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Interstellar Visitors Could Export Terrestrial Life to Other Stars

Wed, 01/22/2020 - 12:23

Life from Earth could spread beyond the solar system if an interstellar visitor skimmed our planet’s atmosphere and picked up microbial hitchhikers. In fact, although the odds are slim, it’s possible Earth has already sent out a slew of these natural probes.

Most research on panspermia, the idea that life could be carried from one world to another, focuses on the blunt-force approach: If a large enough rock slams into a planet infected with life, smaller debris could be blown off world, carrying microorganisms into space, where they could eventually collide with other worlds. But with the recent discovery of two interstellar interlopers, ‘Oumuamua and Borisov, a new question emerged: Could objects like these have scooped up life from Earth’s atmosphere and carried it back out of the system?

“We might have sent thousands of Voyager probes already—thousands of rocks that were laden with Earth microbes.”It’s possible, according to new research from Amir Siraj, an undergraduate at Harvard University, and Harvard theoretical astrophysicist Avi Loeb. Their studies suggest that objects kicked out of other planetary systems, as well as long-period comets from our own solar system, could have potentially hit the atmospheric sweet spot that would allow them to carry microorganisms beyond the heliosphere.

“How many objects could have come just close enough not to hit Earth but just to pick up microbes along the way?” asked Siraj.

Siraj said that he expected the answer would be zero. Instead, his research revealed that as many as 50 interstellar objects could have buzzed Earth over our planet’s lifetime before leaving the solar system for good. As many as 10 long-period comets, born in the solar system and freed by the gravitational pull of passing stars, could also have escaped with life.

“We’ve sent the Voyager probes,” Siraj said, referring to the 1970s human-made satellites on their way out of the solar system carrying information about Earth’s life. “But in fact, we might have sent thousands of Voyager probes already—thousands of rocks that were laden with Earth microbes.”

Catching a Ride

To pick up terrestrial hitchhikers, a comet would need to zip through the upper atmosphere where microorganisms have been detected by other studies but not dip low enough to burn up or collide with our planet. Previous studies have found microorganisms up to 50 kilometers above Earth’s surface, with at least one study identifying them as high as 77 kilometers. For passing comets hoping to pick up a few microbes, higher altitude is better because the lower the comet dips, the more friction it will encounter and the more likely it is to burn up without escaping Earth’s gravitational grasp.

This not-too-high, not-too-low sweet spot changes with the size and density of the objects. Larger, denser objects could survive a trip through regions lower than their more fragile counterparts.

Although hitting that sweet spot can be a challenge, it’s not impossible. Several atmospheric grazing events have been reported since the 1970s, the most recent being a fireball over the Australian desert in 2017. Such fireballs could have scooped up life as they passed through.

Escaping the Solar System Is Just a Start

The optimistic upper atmosphere measurements should be taken with caution, warns Manasvi Lingam, an astrobiologist at the Florida Institute of Technology. Although several studies have found microorganism colonies at altitudes of 50 kilometers, only a single published experiment has identified them at almost 80 kilometers. That experiment hasn’t been replicated since it was performed in 1978. “It’s a somewhat controversial paper,” Lingam said. That doesn’t mean the research was wrong, he said, only that it needed to be independently verified. “Until we have another subject that corroborates the results, we just need to be cautious about using those older studies.”

Siraj didn’t seem overly concerned, pointing out that his team was mostly interested in finding out if the process itself was possible. He expressed optimism that studies like his might spur further investigation into how high microorganisms could survive in the atmosphere.

Hitching a ride is only the first step. Once microorganisms were outside the solar system, radiation from other stars could quickly put an end to any terrestrial life that managed to escape the solar neighborhood. That’s why comets, both local and interstellar, make such good transportation. With their icy surfaces, comets are extremely porous, allowing microorganisms to burrow or be pushed into the depths rather than riding on the surface. Tucked away inside, life could be shielded from harmful radiation by its transportation.

“It’s hard to know what would happen to the microbes,” Lingam said, pointing out that there are few studies on how much protection the icy surface provides from radiation. “If they do make it closer to the center of the object, deep inside the object, I think they would be quite fine. It really depends on how many of them can burrow to a deeper layer.”

The next step, of course, would be colliding with another habitable planet where the microorganisms could flourish. Although the odds of that aren’t covered by the current paper, Siraj said he hopes to study the subject in the near future.

Impacts remain the dominant method for carrying life off Earth, but Earth-grazing objects could provide a significant addition. “This is a very small subset, but perhaps one of the most important,” Siraj said.

The new research was published in the International Journal of Astrobiology.

—Nola Taylor Redd (nola@astrowriter.com; @NolaTRedd), Freelance Science Journalist

Richard J. Walker Receives 2019 Harry H. Hess Medal

Wed, 01/22/2020 - 12:22
Citation Richard J. Walker

Richard J. Walker is the world leader in the field of highly siderophile (or iron-loving) element geochemistry. While this may sound rather esoteric, the impact of Walker’s geochemical and cosmochemical research has changed how we look at Earth’s history, both from the outside in and from the inside out. He developed the rhenium-osmium isotopic method to map—for the first time—the age and evolution of the lithospheric mantle and its domains. Using the same isotopic tool kit, he was able to elucidate the planet’s late accretionary history and was among the first to demonstrate that asteroidal cores, sampled by some iron meteorites, formed very early in solar system history. He further pioneered the use of the platinum-osmium isotope system to test models of Earth’s core-mantle interaction and to refine core crystallization histories of iron meteorite parent bodies. Walker’s group pioneered measurements of tungsten isotope anomalies in early Earth rocks and mantle-derived magmas, demonstrating that primordial materials—formed in the first 50 million years of solar system history—astonishingly survived inside Earth for billions of years and are tapped now by mantle plumes rising from great depths. His group’s most recent discovery that the amount of isotopically anomalous tungsten correlates with that of primordial helium in “hot spot” volcanoes from Hawaii and Iceland has lit the field on fire. This observation implies that primordial materials that formed the first tens of millions of years after initial accretion of the planet remain today sequestered at or near the core-mantle boundary. This research, which requires cutting-edge, high-precision isotope ratio measurements, is a game changer and may reflect diffusive exchange between the deep mantle and the core.

Rich Walker’s impact goes well beyond these scientific discoveries, as he has been an excellent educator and mentor to a myriad of graduate students and postdoctoral scholars, most of whom have gone on to establish themselves in academia, thus representing the next generation of “siderophiles.” Finally, he has devoted significant time, energy, and resources to the University of Maryland (his academic home for the past 30 years), where he is currently the chair of the Department of Geology. Walker has fittingly served as the core of the geochemical community at Maryland, where he has been instrumental in accreting world-class colleagues to the institution, thereby making Maryland a bright center of the geochemical and cosmochemical universe.

For these stellar achievements, we honor Richard J. Walker with the 2019 Harry H. Hess Medal of AGU.

—Alan Jay Kaufman, University of Maryland, College Park; and Roberta L. Rudnick, University of California, Santa Barbara



I’d like to start off by thanking those persons who nominated and selected me for this great award. I am much humbled by this recognition, but I sure do appreciate it! I also want to acknowledge the contributions of numerous postdocs and students, as well as other colleagues at the University of Maryland and beyond. I am fortunate to have worked with a dazzling array of accomplished individuals over the years. All that has been accomplished in my lab has been a result of a team effort. I am not permitted enough words or time to thank everyone individually here, so I offer a blanket, heartfelt thanks!

Perhaps the real stars of this show are the siderophile elements. I am grateful to V. M. Goldschmidt for placing these elements in their own special geochemical category. Due to the difficulties associated with measuring many of these elements, they were somewhat neglected during the first few decades of “modern geochemistry.” During that period, only a few brave souls, such as my early mentor John Morgan, sought to lay the critical groundwork for these elements and map out many of the applications we are pursuing today. The siderophile elements are now a fertile ground for much contemporary geochemical and cosmochemical research.

I began work on two siderophile elements, rhenium and osmium, while a postdoc in the mid-1980s. At the time, there were few data published for the associated isotope system, so exploring it seemed like a good thing to do. Studies involving the system are now quite common, and it is applied to a much wider range of problems than we ever envisioned in the 1980s. Accompanied by improvements to chemical separation techniques and mass spectrometers, my group has grown our list of favorite siderophile elements to include tungsten, ruthenium, and molybdenum. These elements are especially interesting because of their participation in short-lived radioactive decay systems and because their nucleosynthetic variability allows their use in tracing planetary genetics.  The future is bright, as there is much yet to be learned from this group of elements.

To end I would like to acknowledge and especially thank my wife, Mary Horan. Much of the research I have been involved with over the decades has been supplemented by data provided by her, all the while many of our dinner conversations have strayed into discussions of arcane geochemical issues. Much of what I’ve accomplished would not have been possible without her contributions.

Thanks again to all!

—Richard J. Walker, University of Maryland, College Park

S. Majid Hassanizadeh Receives 2019 Robert E. Horton Medal

Tue, 01/21/2020 - 12:34
Citation S. Majid Hassanizadeh

Majid Hassanizadeh has made seminal contributions to hydrological sciences through pioneering and highly impactful research in the formulation of fundamental theories for flow and transport in porous media and is most deserving of receiving this honor. With this recognition, he joins a group of world leaders and pioneers who changed the field of hydrology with lasting scientific and broad societal impacts.

Dr. Hassanizadeh, in his almost 40-year-long career, has made significant contributions to the fundamentals of porous media processes that have led to a new paradigm in modeling critical porous media–related processes in the hydrologic cycle, geologic media, and industrial systems. Early in his career, in collaboration with William Gray, he developed a rigorous and unified approach based on averaging and the principles of physics and thermodynamics, referred to as the “hybrid mixture theory” and “averaged thermodynamic approach” for basic porous media process formulation. The approach has been employed to derive new and advanced theories for non-Fickian and high-concentration dispersion and nonequilibrium capillarity and to extend Darcy’s law for two-phase flow. This work identified a new macroscopic state variable for two-phase flow, called fluid-fluid specific interfacial area, which explicitly accounts for the physics of phase interfaces and allows physically based modeling of capillary effects. He also derived a theory that allows computing the distribution of fluid saturation fields as well as the spatial and temporal variations of the average interfacial area. His pioneering work has contributed some of the few new additions to theories of two-phase flow that have existed for decades. These formulations have also resulted in a vast body of research by mathematicians, experimentalists, and numerical modelers. The power of the averaged thermodynamic approach was further demonstrated through the introduction of the new concept of the “representative elementary watershed” that allows for physically based modeling of hillslope processes and channel networks.

Majid’s services to the field as an editor and associate editor of leading hydrology journals, organizer of major conferences, and mentor of young researchers are unparalleled. As a scientist with a vision and a sense of service to the community, he set up the International Society for Porous Media (InterPore), dedicated to establishing porous media science as a new discipline. Majid’s leading role in porous media research has earned him numerous awards and recognitions, including the Royal Medal of Honor of the Netherlands (Knight of the Order of the Netherlands Lion), which is one of the highest civilian awards.

—Tissa Illangasekare, Colorado School of Mines, Golden



I am extremely honored to receive the Horton Medal. After a long journey in research and education, it is the most rewarding feeling to know that many have found value in my work. I am grateful to my nominator, Tissa Illangasekare, and supporters Mike Celia, Rien van Genuchten, and Günter Blöschl, who have followed my work closely and, most importantly, have offered their sustained support and valuable friendship.

When I was a child in Iran, I was always fascinated by natural springs, where the water seemed to appear from nowhere. Also, qanats that bring groundwater to the land surface by gravity were a mystery to me. Reading through Persian literature, one notices the precious role groundwater played in the rich Iranian history and civilization. No wonder, in pursuing advanced studies, I chose groundwater as my focus. My Ph.D. research was in obtaining generalized laws of fluid flow in porous media. Under the guidance of William Gray, I was able to develop a unified approach based on combining volume averaging and rational thermodynamics for deriving equations governing fluids flow and solute transport in porous media. This work led to a truly generalized Darcy’s law for two-phase flow and a related nonequilibrium capillarity formulation. According to standard two-phase flow theory, capillary pressure is equal to the difference in individual fluid pressures, and saturation is the only state variable needed to describe the flow behavior. My work allowed me to question these long-standing assumptions. In particular, it showed that we need to include information about how fluids are distributed in the pores at a given saturation, and it naturally led to the introduction of fluid-fluid interfaces as a new state variable for fully characterizing two-phase flow. There is now overwhelming evidence that at any given saturation, fluids within pores can be distributed in many different configurations. The developed interfacial area model of two-phase flow and the nonequilibrium capillarity model have allowed us to describe complex processes in industrial porous media, such as diapers, fuel cells, and paper.

I am very aware that lifetime achievements, recognized by the Horton Medal, are not achieved by one individual. I have been blessed to have had the best people to help me realize this achievement. I am enormously grateful to my family, students, collaborators, and colleagues for their countless contributions over the years, helping me to get here. I proudly share this recognition with them while dedicating the medal itself to all Iranian scientists who, under very trying conditions, continue exploring new knowledge in many creative ways.

—S. Majid Hassanizadeh, Department of Earth Sciences, Utrecht University, Netherlands

The Shape of Watersheds

Tue, 01/21/2020 - 12:32

Historically, freshwater systems have been given short shrift in research on biogeochemical cycles.

“Relative to their area, freshwater systems are remarkably important to the global carbon cycle.” “For a long time, the freshwater contributions to the global carbon cycle were assumed to be negligible,” said Daniel Schindler, a limnologist at the University of Washington in Seattle. “But we’ve known for a few decades now that relative to their area, freshwater systems are remarkably important to the global carbon cycle.”

Yet despite this importance, we still know very little about how these freshwater systems will respond to climate change.

A recent study by Schindler and fellow limnologist Kathi Jo Jankowski of the U.S. Geological Survey sheds new light on the matter.

Scientists know that much of the organic carbon in streams and rivers gets transported downstream to the ocean, but a lot of organic carbon gets processed by local ecosystems instead. The organisms in these ecosystems convert the organic carbon into carbon dioxide, which bubbles away into the atmosphere. This process is known as ecosystem respiration.

Temperature has a significant effect on ecosystem respiration. In part, the reason is microbial decomposition of organic matter generally happens faster at warmer temperatures, said Schindler.

“It’s just like putting your leftovers in the fridge versus in the closet,” he said. “If you put them in the closet, they stay warm and they decompose really rapidly.”

But even for streams in the same area of the world, there are big differences in how different streams respond to changes in temperature. Schindler and Jankowski wanted to figure out why.

The Impact of Topography

The answer lies in the shape of the landscape.

Over the course of 4 years, Jankowski and Schindler gathered data from streams in the pristine wilderness of the Wood River system in southwest Alaska. They measured the temperature, ecosystem respiration, and chemical composition of the streams and gathered data about the geomorphology of the stream’s watershed—in other words, the shape of the area of land drained by the stream. The geomorphology of a watershed has a huge impact on the temperature sensitivity of carbon processing in stream ecosystems.

They found that the geomorphology of the watershed had a huge impact on the temperature sensitivity of carbon processing in stream ecosystems. Ecosystem respiration was much more sensitive to temperature in streams that drained flat watersheds compared to streams that drained steep watersheds.

Scientists think that this difference in sensitivity is because watershed morphology affects the quality of organic material that ends up in freshwater systems.

“We know that streams carry a signature of the organic matter that they either receive from the surrounding watershed or that they produce in situ through algal growth,” said Schindler.

Schindler said that most of the organic carbon in streams that drain steep watersheds comes from algae in the streams themselves. This type of organic carbon is really easy for microbes to break down. And because it’s so easy, higher temperatures don’t really affect how fast the microbes can process the carbon.

On the other hand, organic matter in streams that drain flat watersheds tends to come from the soils in the watersheds, said Schindler. Flat watersheds produced streams with organic carbon of lower quality. This organic carbon is harder for microbes to decompose, but higher temperatures can really give microbes a boost when they’re tackling this tricky (or recalcitrant) organic matter.

Jim Hood, an aquatic ecologist at The Ohio State University in Columbus, said that this paper has important implications for our understanding of freshwater ecosystem processes and biogeochemistry on a larger scale. “The really fantastic thing is that by linking [temperature dependency of ecosystem respiration] to geomorphology and then linking it again to the quality of the carbon, they allow us to extend their findings to other systems.” Hood was not involved in the research.

He said that a better understanding of these admittedly complex biological processes is crucial for improving our models of global carbon cycles and our predictions of how they will be affected by climate change.

—Hannah Thomasy (@HannahThomasy), Freelance Science Writer

Even Tardigrades Will Feel the Heat of Climate Change

Tue, 01/21/2020 - 12:31

The microscopic water bears that can survive desiccation, extreme cold, and even trips to the Moon have a key weakness: heat. A recent study tested the survivability of a tardigrade species at elevated temperatures over an extended period. The team found that the lethal temperature for active tardigrades is only 1.2°C hotter than the maximum recorded temperature where the samples were taken.

“We can conclude that active tardigrades are vulnerable to high temperatures, though it seems that these critters would be able to acclimatize to increasing temperatures in their natural habitat,” lead author Ricardo Neves said in a statement. Neves is a postdoctoral researcher in cell biology and physiology at the University of Copenhagen in Denmark.

When given time to adjust, the active tardigrades could withstand slightly higher temperatures for the experimental time frame. Desiccated tardigrades—inactive from being dehydrated—could withstand significantly higher temperatures for a longer time.

Tardigrades Can’t Stand the Heat

This is not the first study to test the upper limits of tardigrades’ heat tolerance, but it is the first to test the animal’s resilience for an hour or longer, the team said. The researchers gathered samples of Ramazzottius varieornatus, a tardigrade species typically found in temporary freshwater habitats, from a roof gutter in Nivå, Denmark.

The researchers exposed tardigrades to different levels of heat for 1 and 24 hours to find the lethal temperature, which they defined as the temperature at which 50% of the population died. They tested active tardigrades, desiccated tardigrades, and active tardigrades given a period of acclimation.

Active tardigrades were the most vulnerable to heat: lethal temperatures at 1 hour were 37.1°C without acclimation and 37.6°C with a short acclimation period. Desiccated tardigrades were more heat resistant than active ones, just like they are more tolerant of the cold. Half the desiccated population survived an hour at 82.7°C. For the 24-hour exposure time, however, the lethal temperature dropped significantly to just 63.1°C.

“Its probability to withstand climate change is limited.” “The results indicate that hydrated or desiccated specimens of Ramazzottius varieornatus are able to tolerate high temperatures, but only for a short time,” said Lorena Rebecchi, an associate professor of zoology at the University of Modena and Reggio Emilia in Italy. “This indicates that its probability to withstand climate change is limited.”

Rebecchi, who was not involved with this research, said that the results might be applicable to other tardigrade species—there are more than 1,000. “Some species inhabiting mosses and lichens of temperate regions or Antarctica have a similar tolerance,” she said.

The hottest temperature ever recorded in Denmark was 36.4°C, only 1.2°C higher than the active, acclimated tardigrades’ 1-hour heat tolerance. On average, the maximum temperature for Denmark is around 22°C, but this value is likely to climb in the next decade.

“Tardigrades are renowned for their ability to tolerate extreme conditions,” the researchers wrote, “but their endurance towards high temperatures clearly has an upper limit—high temperatures thus seem to be their Achilles heel.”

Neves and colleagues published these results in January in Scientific Reports.

—Kimberly M. S. Cartier (@AstroKimCartier), Staff Writer

Wildfires, Coal Fires, and Other Things to Get Fired Up About

Fri, 01/17/2020 - 12:56

Here Are the Environmental Justice Stories to Watch in 2020. Are you wondering what 2020 will bring for the environment? Grist has us covered. I liked this quick take on what stories are coming in environmental justice this year. I’ll be keeping watch on the House bill on heat protection in the workplace and on community-driven air pollution monitoring.

—Jenessa Duncombe, Staff Writer


We Save Lives and Crops Every Time a Coal Plant Closes. New research directly links the closing of coal-fired power plants, and the resulting reduction of pollutants added to the environment, to benefits for human health and agriculture—something few previous studies have done. The work indicated that “the shutdown of coal plants across the [United States] between 2005 and 2016 saved 26,610 lives” and about “570 million bushels of corn, wheat, and soybeans in nearby fields.”

—Timothy Oleson, Science Editor


Five Environmental Consequences of Australia’s Fires.

Australia’s wildfire season still has months to go, and the immediate impacts of the fires have been devastating. This is a really good overview of a few of the ways that these fires will continue to affect the world even after they are extinguished.

—Kimberly Cartier, Staff Writer


Our Favorite Science Illustrations of 2019.


I’m always interested in and impressed by how artists can capture tone and convey complicated information in images. Here the design team of Science shares some of its favorites from the past year.

—Faith Ishii, Production Manager


How the Planets Got Their Spots. I enjoyed reading this—I learned some interesting things about how our solar system took on its present configuration.

—Nancy McGuire, Contract Editor


Can We Fix the Air? Probably not. “We could draw down 1 billion tonnes of carbon dioxide by planting trees, 1.5 billion by better forest management, 3 billion by better agricultural practices, and up to 5.2 billion by biofuels with carbon capture. This adds up to over 10 billion tonnes per year. It’s not nearly enough to cancel the 37 billion tonnes we’re dumping into the air each year now.”

—Caryl-Sue, Managing Editor

Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”

Fri, 01/17/2020 - 12:03

Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones.

Dead zones form where photosynthetic algae rapidly flourish in surface waters. As vast numbers of algae die and sink through the water column, aerobic microbes break them down, consuming nearly all available oxygen in the process. With so little oxygen left in deeper waters, microbes are unable to completely decompose much of the sinking organic matter before it settles on the seafloor.

The amount of organic matter in dead zone sediments can inform predictions of climate models, which usually assume that all this matter initially came from algae. However, in recent years, evidence has emerged that some of the organic matter in these sediments is instead produced by anaerobic microbes that eat dissolved inorganic carbon dioxide in oxygen-depleted waters.

To better understand this process, the authors studied microbes in the Arabian Sea, home to the largest dead zone in the world. They used the R/V Pelagia to collect sediment cores in the dead zone and conducted an isotopic analysis to investigate the origins of the organic matter in the cores.

The analysis revealed that anaerobic microbes could be responsible for one fifth of the organic matter found in seafloor sediments of the Arabian Sea dead zone. Climate models that do not account for the influence of such microbes may underestimate the extent to which dead zones will expand as global temperatures rise.

In this investigation, the researchers developed a new strategy for evaluating anaerobic consumption of inorganic carbon in deep waters. The method, which relies on detecting a distinct chemical signature of the microbes known as the “bacteriohopanetetrol stereoisomer,” could aid future investigations of dead zones around the world, they noted. (Global Biogeochemical Cycles, https://doi.org/10.1029/2019GB006282, 2019)

—Sarah Stanley, Science Writer

Maureen E. Raymo Receives 2019 Maurice Ewing Medal

Fri, 01/17/2020 - 12:02
Citation Maureen E. Raymo

Maureen “Mo” Raymo’s contributions to the geosciences transformed the understanding of Earth’s climate on tectonic, orbital, and shorter timescales. Mo pushed the envelope in research on the marine record of orbital variability in Earth’s climate over the past few millions of years and authored highly cited and inspiring papers. She did not remain within this broad topic but branched out to research linkages between climate and tectonic regimes, climate variability and oceanic geochemical cycles (including the carbon cycle), and the effects on deep-sea biota and deep-sea circulation patterns. She provided new insight into the correlation between ocean circulation and climate in SE Asia, Africa (over the time of evolution of humans), and the U.S. West—an impossibly impressive list. Her research on the interplay among ocean circulation, ice sheets, and climatic records over the initiation of Northern Hemispheric glaciation and changes in the dominant variability of glacial-interglacial climate change has inspired a large volume of research that is important for our understanding of changes in Earth’s climate.

In addition to her scientific excellence, Mo has been a superb supporter of her many undergraduate and graduate students, as well as postdoctoral advisees, encouraging them to bring out the best in their research and copublishing outstanding work. She has been a major contributor to the paleoclimate research that has been used in the evaluation of anthropogenic climate change and cited in the Intergovernmental Panel on Climate Change reports. In addition, she has been a popularizer of science, as shown in the book Written in Stone: A Geological History of the Northeastern United States, cowritten with her father. This book is an excellent example of making science accessible to people who are interested but not professionals. This interest in making science accessible to nonprofessionals is also shown in her active involvement in public lectures on climate change, in producing web content (e.g., “How high will the waters rise?”), and in contributing to articles for the general public (“How the New Climate Denial Is Like the Old Climate Denial,” February 2017,  Atlantic).

Mo Raymo has served the paleoclimate community in many ways, including decades of service in the Ocean Drilling Programs, as well as membership in the Advisory Council of the Climate Science Legal Defense Fund. At a time when not only climate change science but science in general is under assault, it is exciting and gratifying to see that Mo Raymo, who combines excellence in research with advocacy for science, has been rewarded with the Maurice Ewing Medal.

—Ellen Thomas, Yale University, New Haven, Conn.; also at  Wesleyan University, Middletown, Conn.



Thank you, Robin; the Navy; my nominator, Ellen Thomas; and fellow AGU members.  It is a wonderful honor to receive the Maurice Ewing Medal especially as, every day, I go to work in the Lamont-Doherty Core Repository, a testament to the foresight of “Doc” Ewing, who insisted that the Lamont research ships collect “a core a day.”  Decades later, a revolution in our understanding of Earth’s natural climate variability would spring from these innocuous cylinders of deep-sea mud.  I arrived at Lamont in 1982, a decade after Ewing’s departure—by that time women had become a significant cohort of the graduate student body.  Today, I would like to thank those gals for providing fellowship, support, and peer mentoring, before “mentoring” was even a word in our vocabulary. Thank you, Delia Oppo, Christina Ravelo, Rosanne D’Arrigo, Terry Plank, Robin Bell, Lisa Tauxe, Julia Cole, Suzanne O’Connell, Emily Klein, Carol Raymond, Kerry Hegarty, Ellen Kappel, Anne Grunow, and others.  Somehow, we all thought a career as a scientist would be possible, even though there was very little physical evidence to that effect.  I believe it was our critical mass that gave us confidence and strength.

Of course, I’d like to also thank my family, my partner, Ray, and especially my now grown children, Victoria and Daniel, for their unwavering love and support over the years. I’d also like to thank two organizations that never made me feel anything less than a scientist fully deserving of a seat at the table—the National Science Foundation and the International Ocean Drilling Programs.  My career would not have been possible without the early support provided by these organizations.  Last, I’d like to thank my colleagues at Lamont, to where I returned in 2011.  It is an absolute pleasure to go to work every day and be among so many smart and inspiring people who are passionate about our planet’s past, present, and future.  I am truly grateful.  Thank you.

—Maureen E. Raymo, Lamont-Doherty Earth Observatory, Columbia University, Palisades, N.Y.

Another Scorcher: 2019 Was the Second-Hottest Year on Record

Thu, 01/16/2020 - 17:03

Global average temperatures in 2019 soared above preindustrial temperatures, making it the second-hottest year on record as greenhouse gas emissions continue to warm the planet. The year was 1.15°C above the 1880–1900 average, second to only 2016.

NASA and the National Oceanographic and Atmospheric Administration (NOAA) released their annual summary yesterday based on temperatures taken from ocean sensors and more than 20,000 land-based weather stations. Independent analyses by the agencies both concluded that 2019 was nearly the hottest worldwide.

“This shows that what’s happening is persistent, not a fluke due to some weather phenomenon.”“We crossed over into more than 2° Fahrenheit (1.1°C) warming territory in 2015 and we are unlikely to go back,” said Gavin Schmidt of NASA. “This shows that what’s happening is persistent, not a fluke due to some weather phenomenon: We know that the long-term trends are being driven by the increasing levels of greenhouse gases in the atmosphere.”

The World Economic Forum’s annual risk report placed environmental issues in its top five for the first time. The list describes threats to “global prosperity” over the next 10 years, identifying risks such as recessions, cyberattacks, and political tensions. This year’s top five threats with the highest likelihood of occurring were all environmental in nature, including risks of extreme weather and biodiversity loss, which are both exacerbated by rising temperatures.

Although the year was the second hottest globally, it topped the charts in some locations, including the state of Alaska. Their annual temperatures were 3.5°C above the 1925–2000 average, making it the hottest on record. The Bering Sea on Alaska’s icy northwest coast was unusually bare for the majority of 2019, reported the New York Times.

The past 5 years have been the hottest since records began in 1880.Among other anomalies: Australia had its warmest year since records began in 1910, and hot, dry air led to the country’s worst-ever bushfire season. Cities in Europe broke records for all-time high temperature records, and one heat wave traveled over Greenland to create the largest ice melt recorded in one day.

The past 5 years have been the hottest since records began in 1880, and Schmidt said that the past decade was the first that stayed above the 1°C global average. The Paris Agreement aims to stop global climate warming at 1.5°C worldwide.

Schmidt guessed that global temperatures will pass 1.5°C by 2035, though global events could change that. “The warming until now, since the 1970s, has been quite close to linear,” he said. “But of course, that depends on what we do with emissions.”

Melting in the Arctic has been particularly stark in the past decade: Retreating snow caps in the Arctic are exposing soil that doesn’t contain radiocarbon, which means that soil hasn’t seen the Sun for at least 57,000 years, said Schmidt. The Arctic is warming 3 times as fast as the rest of the globe because of local feedback loops, like the water and land absorbing more heat as reflective ice melts away.

It is “almost certain” that the next decade will be warmer than the last.Scientists from two other international organizations, the World Meteorological Organization (WMO) and the United Kingdom’s Met Office, also released their global summary of 2019. WMO agreed with NASA and NOAA’s ranking, whereas the Met Office placed 2019 third. (The differences are largely due to how the calculations deal with limited data in the Arctic.)

What will the next decade bring? NOAA meteorologist Deke Arndt said that it is “almost certain” that the next decade will be warmer than the last and that there will be another record-breaking year in store. 2019 may not hold its title for long.

—Jenessa Duncombe (@jrdscience), News Writing and Production Fellow

Scientists Say Land and Ocean Are Key to Tackling Climate Crisis

Thu, 01/16/2020 - 14:48

Scientists laid out strong arguments for Congress to take tougher action on climate change at a hearing on Wednesday, 15 January. The panelists received general agreement from both sides of the aisle, though no significant moves forward were made.

Land Is a Major Key to Solutions

“The value of land that we have not yet changed is immense,” testified Heidi Steltzer to the House Committee on Science, Space, and Technology; she emphasized the importance of protecting land that has not yet been altered and using land to mitigate climate change. Steltzer is a lead author of Intergovernmental Panel on Climate Change’s (IPCC) September 2019 Special Report on the Ocean and Cryosphere in a Changing Climate and a professor of environment and sustainability at Fort Lewis College in Durango, Colo.

“There are limits to what land can do for us in terms of mitigation without incurring sustainability trade-offs, and the land sector cannot fully make up for failing to tackle fossil fuel emissions elsewhere.”“We can restore lands that have been transformed so that they store more carbon, hold on to more soil, and reduce the impact of extreme weather events,” she added. “We can fund both of these efforts: federal funding for lands protection and restoration, forming the foundation for communities to be resilient.”

Stetzer said that she would like to see the development of a new narrative about climate change. “Snow, plants, and soil are renewable resources. We can work to build capacity for the lands to be more vibrant and more healthy and more green and for there to be more snowfall once again, across the U.S.”

Pamela McElwee, a coauthor of the IPCC’s August 2019 Special Report on Climate Change and Land, testified that the report found that land is under growing pressure, with the increasing impacts of climate change visible in many terrestrial ecosystems. However, “there is a finite amount of land, and it’s often under intense competition. There are limits to what land can do for us in terms of mitigation without incurring sustainability trade-offs, and the land sector cannot fully make up for failing to tackle fossil fuel emissions elsewhere,” said McElwee, an associate professor of human ecology at Rutgers University in New Brunswick, N.J.

The Blue and Green Deals

“The ocean is central to Earth’s climate and weather systems as well as our economic growth and national security and must be included in any discussion regarding legislation and policy addressing the environmental changes we see today,” said Richard Murray, deputy director and vice president for research at the Woods Hole Oceanographic Institution in Woods Hole, Mass. [Editor’s note: Richard Murray is also a member of AGU’s Board of Directors.]

He urged Congress to better fund ocean observation data collection. Murray said that this quantitative data “is essential in order to improve climate and weather predictions and our ability to make difficult decisions about how we manage the future.”

“We have the tools and expertise to take on the next generation of technology challenges—including a changing climate. We have a common goal, and I’m more encouraged than ever that we are on the right track.”Also testifying was Michael Shellenberger, founder and president of Environmental Progress, an environmental and anti-poverty organization based in Berkeley, Calif., who urged Congress to support nuclear energy as a significant way to counter climate change. “Perhaps we should call it a green nuclear deal in recognition of its importance, not just to national security but also to the economy, the environment, and the climate,” he said.

On the Right Track

“We know the climate is changing and that global industrial activity has played a role in this phenomenon,” Rep. Frank Lucas (R-Okla.), ranking member of the committee, said at the hearing.

“Prioritizing investments in basic science and energy research will revolutionize the global energy market and dramatically reduce greenhouse gas emissions,” Lucas said. “We have the tools and expertise to take on the next generation of technology challenges—including a changing climate. We have a common goal, and I’m more encouraged than ever that we are on the right track.”

—Randy Showstack (@RandyShowstack), Staff Writer

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