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  • Remembering Dr. J Dungan Smith (1939-2021)
    Monday, September 20, 2021
    Dr. James Dungan Smith is remembered as a great mentor, advisor, scholar, a brilliant and versatile scientist, and a loving father, grandfather and husband. Read More
  • UW part of $25M NSF-funded effort to retrieve Earth's oldest ice core
    Tuesday, September 14, 2021

    University of Washington glaciologists will join colleagues from around the country in a ne!w effortto discover Antarctica's oldest ice and learn more about the history of our planet's climate.

    closeup of ice in metal barrel

    Ice from a more than 1-mile-deep ice core drilled at the South Pole in 2016. That ice extended back more than 54,000 years, while the new effort aims to find an Antarctic ice record that goes back 1.5 million years.T.J. Fudge/University of Washington

    The new Center for Oldest Ice Exploration, or COLDEX, will be created under a five-year, $25 million National Science Foundation grant announced on Sept. 9. Roughly $5 million of that grant will go to the UW.

    UW researchers will lead in aspects of Antarctic fieldwork and modeling to identify the drilling location, deploy new technologies to scan the ice, and use new ways to analyze the ice once it is retrieved. The center will bring together experts from across the United States to generate knowledge about Earth's climate system and share this knowledge to advance efforts to address climate change and its impacts.

    "Establishing a center makes it possible to go after the big scientific goal of finding and analyzing the oldest ice remaining on Earth to a!ddress fundamental questions about the climate system," said co-principal investigator Michelle Koutnik, a UW research associate professor of Earth and space sciences. "This is a tremendous opportunity that will bring together an ambitious research program with coordinated education, outreach and knowledge transfer programs as part of a new center that is founded on broadening participation in ice and climate science."

    Michelle Koutnik, research associate professor in Earth and space sciences, surveys ice motion near the South Pole in 2016 as part of another effort. COLDEX will conduct ground surveys at unexplored locations in East Antarctica that are being targeted as deep ice-core drilling sites.Ben Brand/University of Washington

    The oldest existing ice cores cu!rrently go back 130,000 years in Greenland and 800,000 years in Antarctica. The newly funded effort aims to find a continuous ice core that goes back 1.5 million years, and to recover chunks that are even older. Previous UW research has explored a possible location for this oldest ice record, in the Allan Hills region of East Antarctica.

    A continuous record longer than 1 million years could offer new information about past climate transitions to help understand and predict current changes in the Earth's climate.

    See a related press release from OSU

    "This ice and the ancient air trapped in it will offer an unprecedented record of how greenhouse gases! and climate are linked in warmer climates and will help to advance our understanding of what controls the long-term rhythms of Earth's climate system," said principal investigator Ed Brook at Oregon State University.

    UW researchers will help study potential drilling sites and model ice flow to find a location where the oldest ice-core climate record is preserved in Antarctica; apply new radar techniques for the first time on a large scale; and help develop novel methods for analyzing the ice that will eventually be recovered.

    One aspect of COLDEX will involve new development of a probe, the University of Washington Ice Diver, that melts through layers of ice and provides information about the age of the ice and other data without having to lift a core back up to the surface. The t!echnology is being developed by COLDEX participant Dale Winebrenner, a UW research professor in Earth and Space Sciences and senior physicist at the UW Applied Physics Laboratory, in collaboration with Ryan Bay at the University of California, Berkeley.

    "This is something that has never been done before. The idea is that it would have an optical device that could detect the amount of dust in the ice," Brook said -- without the need for a preexisting borehole.

    person in white suit holding long metal object

    The University of Washington Applied Physics Laboratory's field team lead engineer Justin Burnett holds the Ice Diver during a deployment at Greenland Summit in May 2021. COLDEX will develop a longer version of this probe to reach depths of 3 km (almost 2 miles) into Antarctic ice while including an opt!ical dust sensor.Ben Brand/University of Washington

    Because the atmosphere tends to be dustier during colder periods and after big volcanic eruptions, the researchers expect to be able to count the dust cycles to estimate the age of the ice, even before the ice is recovered and brought back to the laboratory for more detailed analysis.

    "The Ice Diver allows us to reach great depths in the ice for logging dust levels at costs low enough to sample in many places," Winebrenner said.

    Another UW-led effort recently funded by the NSF will obtain a 150,000-year ice core from a nearby site in Antarctica, at Hercules Dome, to explore past changes in the West Antarctic Ice Sheet

    The first fieldwork season is in the planning stages for 2022-2023. Initial on-the-ground work will be done in the Allan Hills region of Antarctic!a and airborne campaigns across a target sector of East Antarctica, Koutnik said. After that, ground surveying will be done in East Antarctica to help target the specific deep drill site. The deep ice core would be extracted in a second five-year phase of COLDEX.

    Other researchers leading the COLDEX effort at the UW are Knut Christianson, T.J. Fudge, Eric Steig, Howard Conway, Ed Waddington and Andrew Schauer in Earth and space sciences.

    "Many researchers at UW, including new young scientists, will come together and contribute to the ambitious center goals of understanding the ice sheet and the climate history," Koutnik said. "This is really exciting science and a fantastic opportunity for our community of researchers at UW to work together and to collaborate across institutions and across disciplines to address major questions in ice core and cryosphere science."

    Other institutional partners on COLDEX include Amherst College; Brown University; Dartmouth College; P!rincetonUniversity; Scripps Institution of Oceanography; the University of California, Berkeley; UC Irvine; the University of Kansas; University of Maine; University of Minnesota, Duluth; University of Minnesota, Twin Cities; and the University of Texas.

    Additional partners include the American Meteorological Society, Inspiring Girls Expeditions, the Earth Science Women's Network and the Alaska Native Science and Engineering Program, helping to meet a program goal of enhancing diversity in Earth science fields. The center will work with the American Meteorological Society's educational arm to develop a summer program on ice cores for K-12 teachers who work with students from underrepresented backgrounds.

    Funding will be available to support research experiences for undergraduate and graduate students and postdoctoral scholars, with the aim of recruiting diverse pools of candidates for those opportunities.

    COLDEX is one of six new science and technology centers a!nnouncedthis month by the National Science Foundation. NSF currently supports 12 centers, with the last group funded in 2016. The objective of the program, established in 1987, is to support transformative, complex research programs in fundamental areas of science that require large-scale, long-term funding.

     

    For more information, contact Koutnik at mkoutnik@uw.edu.

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  • Research, education hub on 'coastal resiliency' will focus on earthquakes, coastal erosion and climate change
    Tuesday, September 7, 2021

    The National Science Foundation has funded a multi-institutional team led by Oregon State University and the University of Washington to work on increasing resiliency among Pacific Northwest coastal communities.

    The new Cascadia Coastlines and Peoples Hazards Research Hub will serve coastal communities in Northern California, Oregon and Washington. The hub's multidisciplinary approach will span geoscience, social science, public policy !and community partnerships.

    exterior of elementary school

    Ocosta Elementary School in Grays Harbor County, Washington, is home to the first tsunami vertical evacuation center in North America, completed in 2016.NOAA

     

    The Pacific Northwest coastline is at significant risk of earthquakes from the Cascadia Subduction Zone, an offshore fault that stretches more than 600 miles from Cape Mendocino in California to southern British Columbia. The region also faces ongoing risks from coastal erosion, regional flooding and rising seas due to climate change.

    The newly established Cascadia CoPes Hub, based at OSU, will increase the capacity of coastal communities to adapt through community engagement and co-production of research, and by training a new generation of coastal hazards scientists and leaders from currently underrepresented communities.

    The initial award is for $7.2 million over the first two years, with the bulk split between OSU and the UW. The total award, subject to renewals, is $18.9 million over five years.

    "This issue requires a regional approach," said co-principal investigator Ann Bostrom, a UW professor of public policy and governance. "This new research hub has the potential to achieve significant advances across the hazard sciences -- from the understanding of governance systems, to having a four-dimensional understanding of Cascadia faults and how they work, and better understanding the changing risks of compound fluvial-coastal flooding, to new ways of engaging with communities to co-produce research that will be useful for coastal planning and decisions in our region. There are a lot of aspects built into this project that have us all excited."

    The community collaborations, engagement and outreach will focus on five areas: Humboldt County, California; greater Coos Bay, Oregon; Newport to Astoria, Oregon; Tokeland to Taholah, Washington; and from Everett to Bellingham, Washington.

    "We have a lot to learn from the communities in our region, and part of the proposal is to help communities learn from each other, as well," Bostrom said!.

    tsunami warning sign on the beach

    A new research hub at the University of Washington and Oregon Stat!e University, funded by the National Science Foundation, will study coastal hazards and how communities can boost their resiliency.Oregon State University

    The Cascadia hub is part of the NSF's newly announced Coastlines and People Program, an effort to help coastal communities become more resilient in the face of mounting environmental pressures. Nearly 40% of the U.S. population lives in a coastal county. The NSF established one other large-scale hub for research and broadening participation, in New Jersey, and focused hubs in Texas, North Carolina and Virginia.

    The Cascadia hub will focus on two broad areas: advancing understanding of the risks of Cascadia earthquakes and other geological hazards to coastal regions; and reducing disaster risk through assessment, planning and policymaking.

    "We're not thinking only about the possibility of o!ne magnitude-9 earthquake; this effort is about the fabric of hazards over time," said co-principal investigator Harold Tobin, a UW professor of Earth and space sciences and director of the Pacific Northwest Seismic Network. "The heart of this project is merging physical science and social science with a community focus in an integrated way -- translating scientific discovery with actions that coastal communities can use."

    The project intentionally emphasizes incorporating traditional ecological knowledge from the region's Native American tribes as well as local ecological knowledge from fishers, farmers and others who have personal history and experience with coastal challenges.

    "We are committed to co-producing research together with coastal communities and integrating multiple perspectives about disaster risk and its management," said Nicole Err!ett,an assistant professor in UW's Department of Environmental and Occupational Health Sciences, who is co-leading the hub's Community Adaptive Capacity and Community Engagement and Outreach teams.

    "There are many dimensions to resilience, including economics, health, engineering and more," said principal investigator Peter Ruggiero, a professor at OSU. "This research hub is a way to bring together a lot of groups with interest in coastal resilience but have not had the resources to work together on these issues."

    The research hub's other principal investigators are Alison Duvall, a UW assistant professor of Earth and space sciences who will lead efforts to quantify the timing, triggers and effects of landslide hazards on communities and landscape evolution, and D!waine Plaza, a professor of sociology at OSU. The other institutional partners are Washington Sea Grant, Oregon Sea Grant, University of Oregon, Washington State University, Humboldt State University, the U.S. Geological Survey, the Swinomish Indian Tribal Community, Georgia Tech University and Arizona State University.

    For more information, contact Bostrom at abostrom@uw.edu, Ruggiero at 541-737-1239 or peter.ruggiero@oregonstate.edu and Tobin at htobin@uw.edu.

     

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  • How does the thermal structure of a subduction zone evolve?
    Thursday, August 26, 2021
    EGU Geodynamics blog post features Asst. Prof. Cailey Condit and collaborator Adam Holt's work using geodynamic models to understand thermal evolution over the lifetime of a subduction zone. This work, recently published in the AGU Journal Geochemistry, Geophysics, Geosystems, shows the times scales and magnitudes of cooling as a subduction zone progressively ages. Coupling these geodynamic modelling results with thermodynamic modeling of subducting oceanic lithosphere helps us understand how this thermal structure enacts a first order control on the location, source, and magnitude of dehydration in the subarc, providing fluids to cause melting in the mantle wedge. Read More
  • Volcanic eruptions may have spurred first 'whiffs' of oxygen in Earth's atmosphere
    Wednesday, August 25, 2021

    A new analysis of 2.5-billion-year-old rocks from Australia finds that volcanic eruptions may have stimulated! population surges of marine microorganisms, creating the first puffs of oxygen into the atmosphere. This would change existing stories of Earth's early atmosphere, which assumed that most changes in the early atmosphere were controlled by geologic or chemical processes.

    person crouching in distance on layered rock

    Roger Buick in 2004 at the Mount McRae Shale in Western Australia. Rocks drilled near here show "whiffs" of oxygen occurred before the Great Oxidation Event, 2.4 billion years ago. New analyses show a slightly earlier spike in the element mercury emitted by volcanoes, which could have boosted populations of single-celled organisms to produce a temporary "whiff" of oxygen.Roger Buick/University of Washington

    Though focused on Earth's early history, the research also has implications for extraterrestrial life and even climate change. The study led by the University of Washington, the University of Michigan and other institutions was published in August in the Proceedings of the National Academy of Sciences.

    "What has started to become obvious in the past few decades is there actually are quite a number of connections between the solid, nonliving Earth and the evolution of life," said first author Jana Me!ixnerov?, a UW doctoral student in Earth and space sciences. "But what are the specific connections that facilitated the evolution of life on Earth as we know it?"

    In its earliest days, Earth had no oxygen in its atmosphere and few, if any, oxygen-breathing lifeforms. Earth's atmosphere became permanently oxygen-rich about 2.4 billion years ago, likely after an explosion of lifeforms that photosynthesize, transforming carbon dioxide and water into oxygen.

    UW News | July 2018: “Oxygen levels on early Earth rose and fell several times before the successful Great Oxidation Event

    But in 2007, co-author Ariel Anbar at Arizona State University analyzed rocks from the Mount McRae Shale in Western Australia, reporting a short-term whiff of oxygen about 50 to 100 million years before it became a permanent fixture in the atmosphere. More recent research has confirmed other, earlier short-term oxygen spikes, but hasn't explained their rise and fall.

    In the new study, researchers at the University of Michigan, led by co-corresponding author Joel Blum, analyzed the same ancient rocks for the concentration and number of neutrons in the element mercury, emitted by volcanic eruptions. Large volcanic eruptions blast mercury gas into the upper atmosphere, where today it circulates for a year or two before raining out onto Earth's surface. T!he new analysis shows a spike in mercury a few million years before the temporary rise in oxygen.

    black cylinders of rock with white stripes

    These are drill-cores of rocks from the Mount McRae Shale in Western Australia. Previous analysis showed a "whiff" of atmospheric oxygen preceding the Great Oxidation Event, 2.4 billion years ago. New analyses show a slightly earlier spike in minerals produced by volcanoes, which may have fertilized early communities of microbes to produce the oxygen.Roger Buick/University of Washington

    "Sure enough, in the rock below the transient spike in oxygen we found evidence of mercury, both in its abundance and isotopes, that would most reasonably be explained by volcanic eruptions into the atmosphere," said co!-author Roger Buick, a UW professor of Earth and Space Sciences.

    Where there were volcanic emissions, the authors reason, there must have been lava and volcanic ash fields. And those nutrient-rich rocks would have weathered in the wind and rain, releasing phosphorus into rivers that could fertilize nearby coastal areas, allowing oxygen-producing cyanobacteria and other single-celled lifeforms to flourish.

    "There are other nutrients that modulate biological activity on short timescales, but phosphorus is the one that is most important on long timescales," Meixnerov? said.

    Today, phosphorus is plentiful in biological material and in agricultural fertilizer. But in very ancient times, weathering of volcanic rocks would have been the main source for this scarce resource.

    "During weathering under the Archaean atmosphere, the fresh basaltic rock would have slowly dissolved,! releasing the essential macro-nutrient phosphorus into the rivers. That would have fed microbes that were living in the shallow coastal zones and triggered increased biological productivity that would have created, as a byproduct, an oxygen spike," Meixnerov? said.

    The precise location of those volcanoes and lava fields is unknown, but large lava fields of about the right age exist in modern-day India, Canada and elsewhere, Buick said.

    "Our study suggests that for these transient whiffs of oxygen, the immediate trigger was an increase in oxygen production, rather than a decrease in oxygen consumption by rocks or other nonliving processes," Buick said. "It's important because the presence of oxygen in the atmosphere is fundamental - it's the biggest driver for the evolution of large, complex life."

    Ultimately, researchers say the study suggests how a planet's geology might affect any life evolving on its surface, an understanding that aids in identifying habitab!le exoplanets, or planets outside our solar system, in the search for life in the universe.

    Other authors of the paper are co-corresponding author Eva St?eken, a former UW astrobiology graduate student now at the University of St. Andrews in Scotland; Michael Kipp, a former UW graduate student now at the California Institute of Technology; and Marcus Johnson at the University of Michigan. The study was funded by NASA, the NASA-funded UW Virtual Planetary Laboratory team and the MacArthur Profes!sorship to Blum at the University of Michigan.

     

    For more information contact Meixnerov? at janameix@uw.edu or Buick at buick@uw.edu. Note: Meixnerov? is on European Time; Buick is on Pacific Time.

    NASA: NNX16AI37G, 80NSSC18K0829

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  • A visit to Mt. Baker’s Easton Glacier
    Friday, July 30, 2021
    This week, a few members of our UW News team joined glaciologists from the UW Department of Earth & Space Sciences on a trip to Mt. Baker. Students that came along got a pop quiz on glaciology from their professor on the hike up, and we learned about how the recent heat wave impacted the snow melt on the ice. Taryn Black, a PhD candidate in the department, led the hike and is featured in this video. Read More
  • Edge of Pine Island Glacier's ice shelf is ripping apart, causing key Antarctic glacier to gain speed
    Monday, June 14, 2021

    The ice shelf on Antarctica's Pine Island Glacier lost about one-fifth of its area from 2017 to 2020, mostly in three dramatic breaks. The timelapse video incorporates satellite images from January 2015 to March 2020. For most of the first two years, the satellite took high-resolution images every 12 days; then for more than three years it captured images of the ice shelf every six days. Images are from the Copernicus Sentinel-1 satellites operated by the European Space Agency on behalf of the European Union.
    Credit: Joughin et al./Science Advances

    For decades, the ice shelf helping to hold back one of the fastest-moving glaciers in Antarctica has gradually thinned. Analysis of satellite images reveals a more dramatic process in recent years: From 2017 to 2020, large icebergs at the ice shelf's edge broke off, and the glacier sped up.

    Since floating ice shelves help to hold back the larger grounded mass of the glacier, the recent speedup due to the weakening edge could shorten the timeline for Pine Island Glacier's eventual collapse into the sea. The study from researchers at the University of Washington and British Antarctic Survey was published June 11 in the open-access journal Science Advances.

    "We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected," said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory. "The processes we'd been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf."

    ridged ice and airplane wing

    Pine Island Glacier ends in an ice shelf that floats in the Amundsen Sea. These crevasses are near the grounding line, where the glacier makes contact with the Antarctic continent. The photo was taken in January 2010 from the east side of the glacier, looking westward. This ice shelf lost one-fifth of its area from 2017 to 2020, causing the inland glacier to speed up by 12%.Ian Joughin/University of Washington

    Pine Island Glacier contains approximately 180 trillion tons of ice --equivalent to 0.5 meters, or 1.6 feet, of global sea level rise. It is already responsible for much of Antarctica's contribution to sea-level rise, causing about one-sixth of a millimeter of sea level rise each year, or about two-thirds of an inch per century, a rate that's expected to increase. If it and neighboring Thwaites Glacier speed up and flow completely into the ocean, releasing their hold on the larger West Antarctic Ice Sheet, global seas could rise by several feet over the next few centuries.

    These glaciers have attracted attention in recent decades as their ice shelves thinned because warmer ocean currents melted the ice's underside. From the 1990s to 2009, Pine Island Glacier's motion toward the sea accelerated from 2.5 kilometers per year to 4 kilometers per year (1.5 miles per year to 2.5 miles per year). The glacier's speed then stabilized for almost a decade.

    Results show that what's happened more recently is a different process, Joughin said, related tointernal forces on the glacier.

    From 2017 to 2020, Pine Island's ice shelf lost one-fifth of its area in a few dramatic breaks that were captured by the Copernicus Sentinel-1 satellites, operated by the European Space Agency on behalf of the European Union. The researchers analyzed images from January 2015 to March 2020 and found that the recent changes on the ice shelf were not caused by processes directly related to ocean melting.

    "The ice shelf appears to be ripping itself apart due to the glacier's acceleration in the past decade or two," Joughin said.

    Two points on the glacier's surface that were analyzed in the paper sped up by 12% between 2017 and 2020. The authors used an ice flow model developed at UW to confirm that the loss of the ice shelf caused the observed speedup.

    "The recent changes in speed are not due to melt-driven thinning; instead they’re due to the loss of the outer part of the ice shelf," Joughin said. "The glacier'sspeedupis not catastrophic at this point. But if the rest of that ice shelf breaks up and goes away then this glacier could speed up quite a lot."

    It's not clear whether the shelf will continue to crumble. Other factors, like the slope of the land below the glacier's receding edge, will come into play, Joughin said. But the results change the timeline for when Pine Island's ice shelf might disappear and how fast the glacier might move, boosting its contribution to rising seas.

    "The loss of Pine Island's ice shelf now looks like it possibly could occur in the next decade or two, as opposed to the melt-driven subsurface change playing out over 100 or more years," said co-author Pierre Dutrieux, an ocean physicist at British Antarctic Survey. "So it’s a potentially much more rapid and abrupt change."

    Pine Island's shelf is important because it's helping to hold back this relatively unstable West Antarctic glacier, the way the curved buttresses on Notre Dame cathedral hold up the cathedral's mass. Once those buttresses are removed, the slow-moving glacier can flow more quickly downward to the ocean, contributing to rising seas.

    "Sediment records in front of and beneath the Pine Island ice shelf indicate that the glacier front has remained relatively stable over a few thousand years," Dutrieux added. "Regular advance and break-ups happened at approximately the same location until 2017, and then successively worsened each year until 2020."

    Other co-authors are Daniel Shapero and Ben Smith at the UW; and Mark Barham at British Antarctic Survey. The study was funded by the U.S. National Science Foundation, NASA and the U.K. Natural Environment Research Council.

     

    For more information, contact Joughin at ian@apl.washington.edu and Dutrieux at pitr1@bas.ac.uk

    NSF: OPP-1643285, NASA grant: NNX17AG54G

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  • The College of the Environment has created a CoEnv COVID-19 Resources page.
    Thursday, June 10, 2021
    The College of the Environment has created a CoEnv COVID-19 Resources page for faculty, staff, graduate, and undergraduate students. Read More
  • South Pole and East Antarctica warmer than previously thought during last ice age, two studies show
    Thursday, June 3, 2021

    The South Pole and the rest of East Antarctica is cold now and was even more frigid during the most recent ice age around 20,000 years ago -- but not quite as cold as previously believed.

    person with ice core

    Emma Kahle holds ice from 1,500 meters (0.93 miles) depth, the original goal of the South Pole drilling project, in January 2016. New research uses this ice core to calculate temperature history back 54,000 years.Eric Steig/University of Washington

    University of Washington glaciologists are co-authors on two papers that analyzed Antarctic ice cores to understand the continent's air temperatures during the most recent glacial period. The results help understand how the region behaves during a major climate transition.

    In one paper, an international team of researchers, including three at the UW, analyzed seven ice cores from across West and East Antarctica. The results published June 3 in Science show warmer ice age temperatures in the eastern part of the continent.

    The team included authors from the U.S., Japan, the U.K., France, Switzerland, Denmark, Italy, South Korea and Russia.

    "The international collaboration was critical to answering this question because it involved so many different measurements and methods from ice cores all across Antarctica," said second author T.J. Fudge, a UW assistant research professor of Earth and space sciences.

    Antarctica, the coldest place on Earth today, was even colder during the last ice age. For decades, the leading science suggested ice age temperatures in Antarctica were onaverageas much as 9 degrees Celsius cooler than the modern era. By comparison, temperatures globally at that time averaged 5 to 6 degrees cooler than today.

    Previous work showed that West Antarctica was as cold as 11 degrees C below current temperatures. The new paper in Science shows that temperatures at some locations in East Antarctica were only 4 to 5 degrees cooler, about half previous estimates.

    "This is the first conclusive and consistent answer we have for all of Antarctica," said lead author Christo Buizert, an assistant professor at Oregon State University. "The surprising finding is that the amount of cooling is very different depending on where you are in Antarctica. This pattern of cooling is likely due to changes in the ice sheet elevation that happened between the ice age and today."

    The findings are important because they better match results of global climate models, supporting the models' ability to reproduce major shifts in the Earth's climate.

    closeup of ice in metal barrel

    This section of ice core was drilled in 2016 at the South Pole. Drilling more than 1 mile deep accessed older ice containing clues to past climates, providing a clearer picture of Antarctica's transition from the last ice age.T.J. Fudge/University of Washington

    Another paper, accepted in June in the Journal of Geophysical Research: Atmospheres and led by the UW, focuses on data from the recently completed South Pole ice core, which finished drilling in 2016. The Science paper also incorporates these results.

    "With its distinct high and dry climate, East Antarctica was certainty colder than West Antarctica, but the key question was: How much did the temperature change in each region as the climate warmed?" said lead author Emma Kahle, who recently completed a UW doctorate in Earth and space sciences.

    That paper, focusing on the South Pole ice core, found that ice age temperatures at the southern pole, near the Antarctic continental divide, were about 6.7 degree Celsius colder than today. The Science paper finds that across East Antarctica, ice age temperatures were on average 6.1 degrees Celsius colder than today, showing that the South Pole is representative of the region.

    "Both studies show much warmer temperatures for East Antarctica during the last ice age than previous work -- the most recent 'textbook' number was 9 degrees Celsius colder than present," said Eric Steig, a UW professor of Earth and space sciences who is a co-author on both papers. "This is important because climate models tend to get warmer temperatures, so the data and models are now in better agreement."

    "The findings agree well with climate model results for that time period, and thus strengthen our confidence in the ability of models to simulate Earth's climate," Kahle said.

    Previous studies used water molecules contained in the layers of ice, which essentially act like a thermometer, to reconstruct past temperatures. But this method needs independent calibration against other techniques.

    The new papers employ two techniques that provide the necessary calibration. The first method, borehole thermometry, takes temperatures at various depths inside the hole left by the ice drill, measuring changes through the thickness of the ice sheet. The Antarctic ice sheet is so thick that it keeps a memory of earlier, colder ice age temperatures that can be measured and reconstructed, Fudge said.

    The second method examines the properties of the snowpack as it builds up and slowly transforms into ice. In East Antarctica, the snowpack can range from 50 to 120 meters (165 to 400 feet) thick, including snow from thousands of years which gradually compacts in a process that is very sensitive to the temperature.

    "As we drill more Antarctic ice cores and do more research, the picture of past environmental change comes into sharper focus, which helps us better understand the whole of Earth's climate system," Fudge said.

    Fudge, Steig and Kahle are among 40 authors on the Science paper. Other co-authors on the JGR: Atmospheres paper are Michelle Koutnik, Andrew Schauer, C. Max Stevens, Howard Conway and Edwin Waddington at the UW; Tyler Jones, Valerie Morris, Bruce Vaughn and James White at the University of Colorado, Boulder; and Buizert and Jenna Epifanio at Oregon State University.

    Both papers were supported by the U.S. National Science Foundation. Both papers made use of the South Pole ice core, a project that in 2016 completed a 1.75 kilometer (1.09 mile) deep ice core at the South Pole. That project was funded by the NSF and co-led by Steig and Fudge with colleagues at the University of California, Irvine, and the University of New Hampshire.

     

    For more information, contact Fudge at tjfudge@uw.edu, Kahle at eckahle@uw.edu and Steig at steig@uw.edu.

    Part of this articlewere adapted from an OSU press release.

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  • The last glacial maximum in Antarctica wasn't quite so cold.
    Tuesday, June 1, 2021
    New paper led by recent ESS graduate student Emma Kahle, Eric Steig, TJ Fudge, et al. shows it was ~6.5°C colder at South Pole 20 kyr ago. This new result is is better agreement with climate models. The new paper, in Journal of Geophysical Research, also provides a coprehensive analysis of the history of temperature, snowfall, and ice dynamics at the South Pole, as part of the SPICEcore project led by Steig and Fudge, with colleagues at UC-Irvine and the University of New Hampshire. See http://spicecore.org Read More