The collapse of the former Soviet Union in 1991 had social, political and economic effects worldwide. Among them was a suspected role in slowing human-generated methane emissions. Methane had been rising steadily in the atmosphere until about 1990. Atmospheric scientists theorized that economic collapse in the former USSR led to less oil and gas production, and thus a slowdown in the rise of global methane levels, which has since resumed.

But new 91̽�� research uses early satellite records to dispute that assumption. The , published March 12 in the Proceedings of the National Academy of Sciences, finds that methane emissions in Turkmenistan, a former Soviet republic and major oil producer, actually increased in the years following the dissolution of the Soviet Union.

“Methane has these enigmatic trends that we don’t really understand,” said senior author , a 91̽��assistant professor of atmospheric sciences. “One that has always been fascinating is this slowdown in 1992. We find that the collapse of the Soviet Union seems to result, surprisingly, in an increase in methane emissions.”

Carbon dioxide is more important than methane for long-term global warming, but methane plays an important role in the shorter term. One molecule of methane has more heat-trapping power than CO2, and its half-life in the atmosphere is just a decade, meaning its levels can fluctuate.

In recent years, the rise of methane accelerated during COVID-19 lockdowns. Turner’s showed that less driving and thus fewer vehicle emissions containing reactive nitrogen (an air pollutant) likely played a role, because pollution was no longer able to combine with methane molecules to remove them from the atmosphere.

The new study explores a longer-term conundrum: an abrupt slowing in the rise of methane concentrations in the atmosphere in 1992.

Methane’s sources can be hard to untangle since they include both natural sources, such as wetlands, and human-related sources, such as fossil fuels, landfills, livestock digestion and manure. Pockets of methane gas can also escape during extraction of other fossil fuels. Methane is sometimes even burned, or flared, if it is not the main target of exploration.

The new study focused on Turkmenistan, a central Asian oil-producing country where economic data show that gas production dropped by 85% between 1991 and 1998. This steep decline suggests it played a major role in the region’s overall drop in energy production. The country also has relatively little tree cover, making it a good candidate for satellite observations.

The authors used images of Turkmenistan taken by NASA’s , one of the first Earth-observing satellites. First author , a postdoctoral researcher in atmospheric sciences at the UW, and co-author , a former 91̽��undergraduate, identified methane emissions in satellite images and then trained an AI model to catalog similar methane plumes in the entire data set.

“Our field has a lot of data sets, but we don’t have very efficient tools to analyze them,” said He. “This will become worse in the future with more satellites being launched, so we need the help of AI to improve our understanding of atmospheric phenomena.”

Their technique identified 776 plumes over the 25-year period from 1986 to 2011. Analysis shows methane plumes grew in size and became more frequent after 1991, when economic data for Turkmenistan show a decrease in gas production. In some oil and gas basins, methane plumes appeared in 80% to 100% of the clear-sky images during the post-collapse period.

The authors speculate that reasons might include failing infrastructure, broken components, less oversight of oil and gas wells, and fewer export routes, which led to more deliberate or unintentional off-gassing.

“The year 1994 stands out as the year with the largest methane emissions,” Turner said. “That’s fascinating, because that’s the year that Russia refused to allow Turkmenistan to pump gas through its pipelines to European markets. So we think the gas production was still reasonably high, but they couldn’t sell their gas to anyone, resulting in more methane venting to the atmosphere.”

The authors suspect the rest of the former Soviet republics would show similar trends to Turkmenistan, but they can’t yet say for certain.

“More broadly, it begs the question of what drove the 1990s slowdown in atmospheric methane,” Turner said. “I don’t actually know. But when we started this work, I expected to confirm the hypothesis. So it was a pretty surprising finding.”

Turner holds the Calvin Professorship in Atmospheric Sciences at the UW. The other co-author is , a research scientist at Harvard University. Boyd is now a graduate student at Princeton University. This research was funded by NASA, a and the Environmental Defense Fund, a nonprofit based in New York City.

For more information, contact He at taihe@uw.edu and Turner at turneraj@uw.edu.

Volcanoes draw plenty of attention when they erupt. But new research shows that volcanoes leak a surprisingly high amount of their atmosphere- and climate-changing gases in their quiet phases. A Greenland ice core shows that volcanoes quietly release at least three times as much sulfur into the Arctic atmosphere than estimated by current climate models.

The , led by the 91̽�� and published Jan. 2 in Geophysical Research Letters, has implications for better understanding Earth’s atmosphere and its relationship with climate and air quality.

“We found that on longer timescales the amount of sulfate aerosols released during passive degassing is much higher than during eruptions,” said first author , a 91̽��doctoral student in atmospheric sciences. “Passive degassing releases at least 10 times more sulfur into the atmosphere, on decadal timescales, than eruptions, and it could be as much as 30 times more.”

The international team analyzed layers of an ice core from central Greenland to calculate levels of sulfate aerosols between the years 1200 and 1850. The authors wanted to look at the sulfur emitted by marine phytoplankton, which were previously believed to be the biggest source of atmospheric sulfate in pre-industrial times.

“We don’t know what the natural, pristine atmosphere looks like, in terms of aerosols,” said senior author , a 91̽��professor of atmospheric sciences. “Knowing that is a first step to better understanding how humans have influenced our atmosphere.”

The team deliberately avoided any major volcanic eruptions and focused on the pre-industrial period, when it’s easier to distinguish the volcanic and marine sources.

“We were planning to calculate the amount of sulfate coming out of volcanoes, subtract it, and move on to study marine phytoplankton,” Jongebloed said. “But when I first calculated the amount from volcanoes, we decided that we needed to stop and address that.”

The location of the ice core at the center of the Greenland Ice Sheet records emissions from sources over a wide swath of North America, Europe and surrounding oceans. While this result applies only to geologic sources within that area, including volcanoes in Iceland, the authors expect it would apply elsewhere.

“Our results suggest that volcanoes, even in the absence of major eruptions, are twice as important as marine phytoplankton,” Jongebloed said.

The discovery that non-erupting volcanoes leak sulfur at up to three times the rate previously believed is important for efforts to model past, present and future climate. Aerosol particles, whether from volcanoes, vehicle tailpipes or factory chimneys, block some solar energy. If the natural levels of aerosols are higher, that means the rise and fall of human emissions — peaking with the acid rain of the 1970s and then dropping with the Clean Air Act and increasingly strict air quality standards — have had less of an effect on temperature than previously believed.

“There’s sort of a ‘diminishing returns’ effect of sulfate aerosols, the more that you have, the less the effect of additional sulfates,” Jongebloed said. “When we increase volcanic emissions, which increases the baseline of sulfate aerosols, we decrease the effect that the human-made aerosols have on the climate by up to a factor of two.”

That means Arctic warming in recent decades is showing more the full effects of rising heat-trapping greenhouse gases, which is by far the main control on Earth’s average temperature.

“It’s not good news or bad news for climate,” Jongebloed said of the result. “But if we want to understand how much the climate will warm in the future, it helps to have better estimates for aerosols.”

Better estimates for aerosols can improve global climate models.

“We think that the missing emissions from volcanoes are from hydrogen sulfide,” said Alexander, referring to the gas that smells like rotten eggs. “We think that the best ways to improve these estimates of volcanic emissions is to really think about the hydrogen sulfide emissions.”

The study was funded by the U.S. National Science Foundation, NASA and the National Natural Science Foundation of China. Other 91̽��co-authors are undergraduate students Sara Salimi and Shana Edouard, doctoral student Shuting Zhai, research scientist Andrew Schauer, and professor Robert Wood. Other co-authors are Lei Geng, a former 91̽��postdoctoral researcher now at the University of Science and Technology of China; Jihong Cole-Dai and Carleigh Larrick at South Dakota State University; Tobias Fischer at the University of New Mexico; and Simon Carn at Michigan Technological University.

For more information, contact Jongebloed at ujongebl@uw.edu or Alexander at beckya@uw.edu.

Clouds come in myriad shapes, sizes and types, which control their effects on climate. New research led by the 91̽�� shows that splintering of frozen liquid droplets to form ice shards inside Southern Ocean clouds dramatically affects the clouds’ ability to reflect sunlight back to space.

The , published March 4 in the open-access journal AGU Advances, shows that including this ice-splintering process improves the ability of high-resolution global models to simulate clouds over the Southern Ocean – and thus the models’ ability to simulate Earth’s climate.

“Southern Ocean low clouds shouldn’t be treated as liquid clouds,” said lead author , a 91̽��doctoral student in atmospheric sciences. “Ice formation in Southern Ocean low clouds has a substantial effect on the cloud properties and needs to be accounted for in global models.”

Results show that it’s important to include the process whereby icy particles collide with supercooled droplets of water causing them to freeze and then shatter, forming many more shards of ice. Doing so makes the clouds dimmer, or decreases their reflectance, allowing more sunlight to reach the ocean’s surface.

The difference between including the details of ice formation inside the clouds versus not including them was 10 Watts per square meter between 45 degrees south and 65 degrees south in the summer, which is enough energy to have a significant effect on temperature.

The study used observations from a 2018 field campaign that flew through Southern Ocean clouds, as well as data from NASA’s CERES satellite and the Japanese satellite .

Ice formation reduces clouds’ reflectance because the ice particles form, grow and fall out of the cloud very efficiently.

“The ice crystals deplete much of the thinner cloud entirely, therefore reducing the horizontal coverage,” Atlas said. “Ice crystals also deplete some of the liquid in the thick cores of the cloud. So the ice particles both reduce the cloud cover and dim the remaining cloud.”

In February, which is summer in the Southern Ocean, about 90% of the skies are covered with clouds, and at least 25% of those clouds are affected by the type of ice formation that was the focus of the study. Getting clouds right, especially in the new models that use smaller grid spacing to include clouds and storms, is important for calculating how much solar radiation reaches Earth.

“The Southern Ocean is a massive global heat sink, but its ability to take heat from the atmosphere depends on the temperature structure of the upper ocean, which relates to the cloud cover,” Atlas said.

Co-authors of the study are , a 91̽��professor emeritus of atmospheric sciences now at the Allen Institute for AI in Seattle; at Stony Brook University in New York; and , a 91̽��research scientist in atmospheric sciences. The research was funded by the National Science Foundation.

For more information contact Atlas at ratlas@uw.edu.

NSF grants: GS-1660604, AGS-1660609, OISE-1743753

Conditions in the tropical ocean affect weather patterns worldwide. The most well-known examples are El Niño or La Niña events, but scientists believe other key elements of the tropical climate remain undiscovered.

In a recently published in Geophysical Research Letters, scientists from the 91̽�� and NOAA’s Pacific Marine Environmental Laboratory use remotely-piloted sailboats to gather data on , or pockets of cooler air that form below tropical storm clouds.

“Atmospheric cold pools are cold air masses that flow outward beneath intense thunderstorms and alter the surrounding environment,” said lead author , a postdoctoral researcher at the Cooperative Institute for Climate, Ocean and Ecosystem Studies. “They are a key source of variability in surface temperature, wind and moisture over the ocean.”

The paper is one of the first tropical Pacific studies to rely on data from Saildrones, wind-propelled sailing drones with a tall, hard wing and solar-powered scientific instruments. Co-authors on the NOAA-funded study are at CICOES and at NOAA.

Atmospheric cold pools produce dramatic changes in air temperature and wind speed near the surface of the tropical ocean. The pockets of cooler air form when rain evaporates below thunderstorm clouds. These relatively dense air masses, ranging between 6 to 125 miles (10 to 200 kilometers) across, lead to downdrafts that, upon hitting the ocean surface, produce temperature fronts and strong winds that affect their surroundings. How this affects the larger atmospheric circulation is unclear.

“Results from previous studies suggest that cold pools are important for triggering and organizing storm activity over tropical ocean regions,” Wills said.

To understand the possible role of cold pools in larger tropical climate cycles, scientists need detailed measurements of these events, but it is hard to witness an event as it happens. The new study used uncrewed surface vehicles, or USVs, to observe the phenomena.

Over three multi-month missions between 2017 and 2019, 10 USVs covered over 85,000 miles (137,000 kilometers) and made measurements of more than 300 cold pool events, defined as temperature drops of at least 1.5 degrees Celsius in 10 minutes. In one case, a fleet of four vehicles separated by several miles captured the minute-by-minute evolution of an event and revealed how the cold pool propagated across the region.

“This technology is exciting as it allows us to collect observations over hard-to-reach, under-sampled ocean regions for extended periods of time,” Wills said.

The paper includes observations of air temperature, wind speed, humidity, air pressure, sea surface temperature and ocean salinity during cold pool events. The authors use the data to better describe these phenomena, including how much and how quickly air temperatures drops, how long it takes the wind to reach peak speeds, and how sea surface temperature changes nearby. Results can be used to evaluate mathematical models of tropical convection and explore more questions, like how the gusts created by the temperature difference affect the transfer of heat between the air and ocean.

For more information, contact Wills at smwills@uw.edu. Parts of this post were adapted from an in AGU Eos.

New research reveals significant changes to the circulation of the North Pacific and its impact on the initial migration of humans from Asia to North America.

The international , led by the University of St. Andrews in Scotland and published Dec. 9 in Science Advances, provides a new picture of the circulation and climate of the North Pacific at the end of the last ice age, with implications for early human migration.

The Pacific Ocean contains around half the water in Earth’s oceans and is a vast reservoir of heat and carbon dioxide. However, at present, the sluggish circulation of the North Pacific restricts the movement of this heat and carbon dioxide, limiting its impact on climate.

The international team of scientists used sediment cores from the deep sea to reconstruct the circulation and climate of the North Pacific during the peak of the last ice age, roughly 21,000 years ago. Their results reveal a dramatically different circulation in the ice age Pacific, with vigorous ocean currents creating a relatively warm region around the modern Bering Sea.

“Our data shows that the Pacific had a warm current system during the last ice age, similar to the modern Atlantic Ocean currents that help to support a mild climate in Northern Europe,” said lead author , a faculty member at the University of St. Andrews.

The warming from these ocean currents created conditions more favorable for early human habitation, helping address a long-standing mystery about the earliest inhabitants of North America.

“According to genetic studies, the first people to populate the Americas lived in an isolated population for several thousand years during the peak of the last ice age, before spreading out into the American continents,” said co-author , a professor of anthropology at the 91̽�� who studies early communities in the North Pacific.

This hypothesis has been termed the “Beringian Standstill,” and a significant question is where this population lived after separation from their Asian relatives, before deglaciation of the massive ice sheet covering the northern third of North America allowed them to reach and spread throughout the Americas. The new research suggests that these early Americans may have lived in a relatively warm refugium, or habitable refuge, in southern Beringia, on the now submerged land beneath the Bering Sea. Due to the extremely cold climate that dominated other parts of this region during the ice age, it has been unclear, until now, how habitable conditions could have been maintained.

“Our work shows how dynamic Earth’s climate system is. Changes in the circulation of the ocean and atmosphere can have major impacts on how effectively humans may inhabit different environments, which is also relevant for understanding how different regions will be affected by future climate change,” said third author , a postdoctoral researcher in atmospheric sciences at the 91̽��.

Wills researches the overturning circulation in the North Pacific, and did climate modeling work to help understand what the paleoclimate data — compiled by researchers at the University of St. Andrews and the University of California, Irvine — would mean for the region’s climate.

“The warm currents revealed by our data would have created a much more pleasant climate in this region than we might have previously thought,” said second author , a research scientist at the Laboratory for Sciences of Climate and Environment in France.

“This would have created milder climates in the coastal regions of the North Pacific, that would have supported more temperate terrestrial and marine ecosystems and made it possible for humans to survive the ice age in an otherwise harsh climatic period.”

The research was funded by the U.S. National Science Foundation and the U.K. Natural Environment Research Council. Other co-authors are from Scripps Institution of Oceanography; the University of California, Irvine; and the University of California, Riverside.

For more information, contact Fitzhugh at fitzhugh@uw.edu, Wills at rcwills@uw.edu and Gray at william.gray@lsce.ipsl.fr. Contact Rae via communications manager Christine Tudhope, Christine.Tudhope@st-andrews.ac.uk, 01334 467 320 or 07526 624 243 (mobile).

Adapted from a from the University of St. Andrews.

Atmospheric scientists have analyzed how the February near-total shutdown of mobility affected the air over China. Results show a striking drop in nitrogen oxides, a gas that comes mainly from tailpipes and is one component of smog.

Learning how behavior shifts due to the COVID-19 pandemic affect air quality is of immediate importance, since the virus attacks human lungs. The event is also a way for Earth scientists to study how the atmosphere responds to sudden changes in emissions.

“During the February 2020 shutdowns in China there was a large and rapid decline in nitrogen dioxide — an air pollutant largely associated with transportation — that is unprecedented in the satellite record,” said , a 91̽�� doctoral student in atmospheric sciences.

“On the other hand, our analysis shows no dramatic changes in the total amount of aerosol particles in the atmosphere, or in cloud properties. This suggests the immediate climate-related impacts from the shutdown are negligible,” Diamond said.

He is lead author of the published Aug. 19 in Geophysical Research Letters.

While other studies have already looked at air quality during the pandemic, this is the first to take a more rigorous view, using all 15 years of satellite data. It uses a statistical method that compares what was seen in February 2020 to what would have been expected without the pandemic.

“Early in the quarantine period, there was some discussion that the Earth was healing itself, but some of those claims, like the , have turned out to be false,” Diamond said. “The scientific community was interested in documenting what changes actually occurred.”

The authors used data from NASA’s , or OMI, and , or MODIS, which have been monitoring the skies since 2005. These instruments use different wavelengths to monitor quantities like nitrogen oxides, airborne particulates and clouds.

In addition to using a longer record, the model accounted for the expected effects of China’s environmental policies.

“China passed a clean air law in 2013, and ever since you can see that pollution is going down. So just for that reason, we might expect that the pollution in 2020 would be lower than in 2019,” Diamond said.

The analysis also accounted for this past February’s relatively hot and humid weather in China, which made gases more likely to react and form airborne particles.

“You still had some pretty bad smog events happening in the Beijing region, even during the lockdown,” Diamond said.

The authors also considered the atmospheric effects of the Chinese New Year, which is celebrated in either late January or early February and generates both higher particulates from fireworks and lower traffic emissions from people being on holiday.

After accounting for all of these factors, the pandemic’s effect on nitrogen dioxide was a drop of 50% compared to what would be expected for February 2020, a drop unlike any other seen in the satellite observations.

“The difference we see is more than twice as large a drop as anything we saw in the record from 2005 to 2019, including from the 2008 Great Recession. In the statistics of atmospheric science, that’s a giant signal. It is rare to see anything that striking,” Diamond said.

While the change in nitrogen dioxide was dramatic, other quantities showed no significant change. Fine particulate matter, which has a bigger impact on human health and the climate, hardly changed over China during the shutdown. Passenger transportation virtually disappeared during the lockdown, but economic data show that heavy industry and energy production stayed fairly constant, Diamond said.

The fact that some quantities did not change is, for atmospheric scientists, a significant result in itself. Clouds, which are affected by pollution and have the biggest effect on climate, also showed no significant changes.

Co-author , a 91̽��professor of atmospheric sciences, and Diamond collaborated on a recent publication that detected cloud changes due to pollution from ships. That study showed that many years of data were required to detect the effect on clouds.

“Our study suggests that since we found little change in particulate pollution due to COVID-19, we are unlikely to see any change in the clouds unless pollution changes over a longer time period due to a prolonged economic downturn,” Wood said.

Overall, the findings agree with a recent study led by the 91̽��showing that nitrogen dioxide dropped in several American cities during the peak quarantine period, but levels of other pollutants stayed fairly constant.

The response suggests that future clean air policies can’t focus only on transportation emissions.

“When you’re crafting these clean air strategies, you’re probably not going to be able to attack just one sector; you’ll have to address several sectors at once,” Diamond said.

This research was funded by NASA.

For more information, contact Diamond at diamond2@uw.edu or Wood at robwood2@uw.edu.

A new study uses satellite data over the Southern Hemisphere to understand the makeup of global clouds since the Industrial Revolution. This research tackles one of the largest uncertainties in today’s climate models — the long-term effect of tiny atmospheric particles on climate change. 

Research led by the 91̽�� and the University of Leeds in the United Kingdom uses remote, pristine parts of the Southern Hemisphere as a window into the early-industrial atmosphere. 

The team compared satellite measurements of cloud droplet concentration in the atmosphere over the Northern Hemisphere — now heavily polluted with today’s industrial aerosols — and over the relatively pristine Southern Ocean. They used this to measure how particles from pollution may have affected Earth’s temperature since 1850. 

The , published the week of July 27 in the Proceedings of the National Academy of Sciences, suggest that early industrial aerosol concentrations and cloud droplet numbers were much higher than many global climate models estimate. This could mean that human-generated atmospheric aerosols, or particulate pollution, is not damping the warming from carbon dioxide as much as some climate models estimate. The study suggests that the cooling effect of pollution is likely to be more moderate.  

“One of the biggest surprises for us was how high the concentration of cloud droplets is in Southern Ocean clouds,” said co-lead author , a 91̽��doctoral student in atmospheric sciences. 

The Southern Ocean surrounding Antarctica has few aerosol particles from human activity, but the cloud droplet concentration remains high, especially in summer. 

“The way that the cloud droplet concentration increases in summertime tells us that ocean biology is playing an important role in setting cloud brightness in unpolluted oceans, now and in the past,” McCoy said.

“We see high cloud-droplet concentrations in satellite and aircraft observations, but not in climate models,” she added. “This suggests that there are gaps in the model representation of aerosol-cloud interactions and aerosol-production mechanisms in pristine environments.”

Climate models represent the global warming effect of greenhouse gases as well as the cooling effects of atmospheric aerosols. The tiny particles that make up these aerosols are produced by human-made sources such as emissions from cars and industry, as well as natural sources, such as phytoplankton and sea spray. 

These particles can influence sunlight and heat flow within the atmosphere as well as interact with clouds. One way the particles affect clouds is by increasing the cloud droplet concentration, causing the clouds to reflect more sunlight back to space.

However, little is known about how aerosol concentrations have changed over the industrial era. This restricts the climate models’ ability to accurately estimate the long-term effects of aerosols on global temperatures. 

“Limitations in our ability to measure aerosols in the early-industrial atmosphere have made it hard to reduce uncertainties in how much warming there will be in the 21st century,” said co-lead author , who completed the work at the University of Leeds and is now an assistant professor at the University of Wyoming.

Daniel McCoy, a former 91̽��doctoral student and Isabel’s brother, authored a previous 91̽��study showing that biological activity in the Southern Ocean influences clouds more than expected. 

“Ice cores provide carbon dioxide concentrations from millennia in the past, but aerosols don’t hang around in the same way,” he said. “One way that we can try to look back in time is to examine a part of the atmosphere that we haven’t polluted yet. 

“Isabel proposed this work based on what she saw flying out of Tasmania as part of the 91̽��team participating in the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES). These observations were supported by other recent field data and this grew our confidence in what we had been seeing from space.” 

Measurements over the Southern Ocean and other remote locations can ultimately help improve global climate models.

“As we continue to observe pristine environments through satellite, aircraft, and ground platforms, we can improve the representation of the complex mechanisms controlling cloud brightness in climate models and increase the accuracy of our climate projections,” Isabel McCoy said.

Other co-authors are Robert Wood at the UW; Leighton Regayre, Daniel P. Grosvenor, Paul Field, and Ken Carslaw at the University of Leeds; Duncan Watson-Parris at the University of Oxford; Jane P. Mulcahy at the U.K. Met Office; Yongxiang Hu at NASA Langley Research Center; Frida Bender at Stockholm University; and Hamish Gordon at Carnegie-Mellon University.

Research funders include the National Science Foundation, NASA, the U.K. Natural Environment Research Council and the European Union’s Horizon 2020 program.

For more information, contact Isabel McCoy at imccoy@uw.edu or Daniel McCoy at dmccoy4@uwyo.edu.

This post has been adapted from a University of Leeds .

Ancient air samples from one of Antarctica’s snowiest ice core sites may add a new molecule to the record of changes to Earth’s atmosphere over the past century and a half, since the Industrial Revolution began burning fossil fuels on a massive scale.

While carbon dioxide and methane are well known, researchers at the 91̽�� and the University of Rochester are part of a team working to trace a much rarer gas, present at less than one in a trillion molecules. Though rare, the atmospheric detergent known as hydroxyl can scrub the atmosphere and determine the fate of more plentiful gases that affect Earth’s climate.

An Antarctic last winter led by the U.S. and Australia has successfully extracted some of the largest samples of air dating from the 1870s until today. These samples are a first step to learning the changes in hydroxyl concentration over the past 150 years. Early results from the fieldwork were this week at the American Geophysical Union’s annual fall meeting in San Francisco.

“It’s probably the most extreme atmospheric chemistry you can do from ice core samples, and the logistics were also extreme,” said , a postdoctoral researcher with dual appointments at the 91̽��and at the University of Rochester.

But the months the team spent camped on the ice at the snowy site paid off.

“This is, to my knowledge, the largest air sample from the 1870s that anyone’s ever gotten,” Neff said. His 10 weeks camped on the ice included minus-20 degrees Fahrenheit temperatures and several snowstorms, some of which he shared from Antarctica via Twitter.

https://twitter.com/peter_neff/status/1092585377506910208

Air from deeper ice cores drilled in Antarctica and Greenland has provided a record of carbon dioxide and methane, two greenhouse gases, going back thousands of years. While carbon dioxide has a lifetime of decades to centuries, an even more potent gas, methane, has a lifetime of just nine or 10 years.

Pinpointing the exact lifetime of methane, and how it has changed over the years, depends on the concentration of hydroxyl. That number is important for the global climate models used to study past and future climate.

To trace the history of hydroxyl, a fleeting molecule with a lifetime of less than a millionth of a second, a field campaign in late 2018 and early 2019 drilled ice to study this very reactive gas by examining its slightly more plentiful companion, carbon with 14 neutrons bonded to an oxygen atom, or “carbon-14 monoxide,” which is chemically destroyed by hydroxyl and so tracks hydroxyl’s concentrations.

Researchers get the carbon-14 monoxide gas from bubbles in the ice that form when snow is compressed.

“The special thing about glacier ice is that it always has these air bubbles,” Neff said. “Any glacier in the world is going to have that bubbly texture, because it started as a pile of six-fingered snowflakes, and between those fingers is air.”

One or several decades after hitting the ground, bubbles become completely sealed off from their surroundings due to compression under layers of snow. The heavy snow accumulation at Law Dome means plenty of air bubbles per year, and provides a thick enough shield to protect the carbon-14 monoxide from solar radiation.

The international team extracted about two dozen 3-foot-long sections of ice per day, then put the tubes of ice in a snow cave to protect them from cosmic rays that are stronger near the poles. Those rays can zap other molecules and distort the historic record.

“Once the samples are at the surface, they’re hot potatoes,” Neff said.

The day after extracting a core, the team would clean the ice and place it in a device of Neff and his University of Rochester postdoctoral supervisor Vasilii Petrenko’s design: a 335-liter vacuum chamber in a warm bath to melt the ice and process the samples at their source, to avoid contamination and collect the biggest air samples.

“A single sample size was about 400 or 500 kilograms of ice, about the same weight as a grand piano, to get enough of that carbon-14 monoxide molecule,” Neff said. “At the field camp we turned 500 kilos of ice into one 50-liter canister of air.”

https://twitter.com/peter_neff/status/1054564249391910912

The team retrieved 20 barrel-shaped canisters of air from various time periods.

Analysis over the coming months will aim to produce a concentration curve for carbon-14 monoxide and hydroxyl over the decades, similar to the now-famous curves for carbon dioxide and methane. The curves show how gas concentrations have changed in the atmosphere since the industrial era.

Throughout the effort, Neff has also explored more lighthearted combinations of ice and air. During a trip in early 2016 to prepare for this effort, Neff did an on social media when he posted it in February 2018.  The video captures the sound a piece of ice makes when dropped down the tunnel created by an ice core drill.

https://twitter.com/peter_neff/status/968911225919700992

He shared more photos and videos during this past winter’s expedition to Antarctica, sometimes within hours of returning from a remote camp to an internet-connected research station.

“It’s great to be able to share something about Antarctica, from Antarctica,” Neff said. “It’s a way that we as geoscientists can share with people the work that they help to support.”

The project is led by Petrenko at the University of Rochester and David Etheridge at the Commonwealth Scientific and Industrial Research Organisation in Australia. Other collaborators on the results being presented at the meeting in San Francisco include Scripps Institution of Oceanography, the Australian Nuclear Science and Technology Organisation, the Australian Antarctic Division and Oregon State University. The research was funded by the U.S. National Science Foundation and the Australian Antarctic Division.

###

For more information, contact Neff at neffp@uw.edu. He is not attending AGU but is available by email.

The Southwest has always faced periods of drought. Most recently, from late 2011 to 2017, California experienced years of lower-than-normal rainfall.

El Niño is known to influence rain in the Southwest, but it’s not a perfect match. New research from the 91̽�� and the Woods Hole Oceanographic Institution explores what conditions in the ocean and in the atmosphere prolong droughts in the Southwestern U.S.

The answer is complex, according to a published Aug. 6 in the , a journal of the American Geophysical Union.

“What causes droughts that last for decades in some parts of the world, and why does that happen? Can we predict it?” said first author , a 91̽��postdoctoral researcher in atmospheric sciences. “Our study shows that when you have a large El Niño event, and a La Niña event is coming next, that could potentially start a multiyear drought in the Southwestern U.S.”

The general rule of thumb had been that El Niño years — when the sea surface in a region off the coast of Peru is at least 1 degree Celsius warmer than average — tend to have more rainfall, and La Niña years, when that region is 1 degree Celsius cooler than average, tend to have less rain. But that simple rule of thumb doesn’t always hold true.

“People often think that El Niño years are wet in the Southwest, but research over the years shows that’s not always the case,” Parsons said. “An El Niño sometimes brings rain, or can help cause it, but frequently that’s not what makes any given year wet.”

The recent 2015 winter was a case in point, and Parsons said that event helped inspire the new study. As 2015 shaped up to be an El Niño year, there was hope that it would end California’s drought. But the rain didn’t start to arrive until the following year.

The new study uses climate models to explore the relationship between the world’s largest ocean and long-term droughts in the Southwestern U.S., which includes California, Nevada, Utah, Arizona and western Colorado and New Mexico.

“When it’s dry one year after another, that’s hard on people, and it can be hard on ecosystems,” Parsons said.

Weather observations for the Southwest date back only about 150 years, and in that time, only 10 to 15 multiyear droughts have occurred. So the authors used climate models that simulate thousands of years of weather, including over 1,200 long-term droughts in the Southwest. The authors defined a drought as multiple years with lower-than-average rainfall. The drought ended when the region had two consecutive wetter-than-normal years.

“A lot of people have looked at what’s going on over the ocean during a drought, but we’re trying to take a step back, and look at the whole life cycle — what happens before a drought starts, what maintains a drought, and then what ends it,” Parsons said.

Parsons and co-author at the Woods Hole Oceanographic Institution separated the system into pre-drought, during-drought and post-drought periods. They found that before a long-term drought starts, there is often an El Niño year. Then the first year of a drought is often colder than normal in that region of the ocean, though it might not be enough to qualify as a La Niña year.

“Where that warm pool of water sits ends up disturbing, or changing, the jet stream, and that shifts where the winter rains come in off the ocean in the Northern Hemisphere winter,” Parsons said. “La Niña can kick off a drought, but you don’t have to have multiple La Niña events to continue the drought and keep the Southwest dry.”

An El Niño that’s slightly farther offshore than normal, in the central tropical Pacific, often ends the drought. But the study shows that’s not always true: About 1 in 20 drought years could see an El Niño that doesn’t deliver rain.

Better understanding of long-term droughts could help managers make decisions like whether to release water from the Colorado River, or whether to save some in anticipation of another low year.

The study was funded by the Washington Research Foundation. Weather data and climate model results came from the National Science Foundation, the National Oceanic and Atmospheric Administration and the U.S. Department of Energy.

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For more information, contact Parsons at lakp@uw.edu.

A new study has found that a pattern of ocean temperatures and atmospheric circulation has offset most of the impact of global warming on mountain snowpack in the western U.S. since the 1980s.

The from Oregon State University, the 91̽�� and Lawrence Livermore National Laboratory was published Jan. 11 in Geophysical Research Letters.

“The western U.S. has received a big assist from natural variability over the past 35 years,” said lead author at Oregon State University, who began thinking about the project as a doctoral student in atmospheric sciences at the UW. “That’s been great for us so far, but it’s bad news for the future.”

Western snowpack brings white-capped mountaintops and happy skiers, but it also plays a crucial role in our water supplies by storing freshwater as snow that will melt in the drier summer months in places like Washington, Oregon and California.

The research was prompted by conversations that began at the UW.

“There were a lot of discussions within the department of the surprising stability of the western U.S. snowpack, because it went against the predictions,” said co-author , a postdoctoral researcher at the UW’s Joint Institute for the Study of the Atmosphere and Ocean.

The authors used snow measurements that began in 1983 at 329 automated stations across the central and western United States, mostly at high-elevation sites. During the subsequent 35-year observational period, only four sites experienced a statistically significant decline in April 1 snowpack, while the others showed no significant trend.

The authors compared the snow measurements with oceanic and atmospheric climate data to see which most affected the snow accumulation. They then used a climate model for the whole 35-year observation period to determine what was affecting the overall trend. Results show that without the contribution from natural variability in the nearby Pacific Ocean, the western U.S. would have experienced a much larger decline in winter snowpack, especially in the Cascades and Sierra Nevada, due to an average winter warming of about 1 degree Celsius over the western U.S.

In Washington’s portion of the Cascade Range, for example, the authors found that rising temperatures due to human emissions would, on their own, have caused average snowpack on April 1 to decline by about 23 percent since the early 1980s, with a range of 2 to 44 percent decrease. However, this was offset by an increase in snowpack resulting from natural variability. The two factors together explain why snowpack has not declined significantly over the past 35 winters.

The natural variability is an atmospheric circulation pattern associated with stronger winds that bring more moisture from the Pacific Ocean. The pattern is driven by natural, long-term variations in Pacific Ocean temperatures. The northeast Pacific has not warmed as much as the land in recent decades, and stronger westerly winds have thus delivered more moisture to the coastal mountain ranges.

“One of the more important broader questions in climate science right now is: What is the Pacific Ocean doing, and why is it doing it? The top-level story is that the northeast Pacific hasn’t really exhibited a lot of warming,” Proistosescu said.

By contrast, during the 2015 year of “,” when the northeast Pacific had unusually warm surface temperatures, the West saw markedly less snow. This, the authors say, may be what the future looks like.

Siler said he expects a different scenario to play out over the next few decades, as the current phase of natural variability subsides, likely giving way to a circulation pattern that is less favorable for snowpack accumulation. The northeastern Pacific is likely to warm eventually, portending an accelerated decline in winter mountain snowpack over the next few decades.

“Natural variability has masked the impact of global warming on snowpack for as long as I’ve been alive,” said Siler, who was born in 1983. “But in the next few decades, I think we’re more likely to see natural variability amplify, rather than offset, the loss of snowpack due to global warming.”

The other co-author is , a former 91̽��graduate student who is now a research fellow at Lawrence Livermore National Laboratory in Berkeley.

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For more information, contact Proistosescu at cproist@uw.edu or Siler at 541-737-8633 and nick.siler@oregonstate.edu.

Portions of this post were adapted from an OSU .