From flakes to floes: snow in the changing Arctic sea-ice system

This video is a part of our Cryosphere Seminar series. It is led by Melinda A. Webster. Abstract: Snow is one of the most reflective and insulative natural materials on Earth. As a consequence, it is an integral component of the sea-ice and Earth’s climate systems. For Arctic sea ice, snow’s high albedo reduces solar absorption and transmittance, which lessens sea-ice melt and ocean warming in summer. In winter, snow's insulating properties inhibit sea ice growth and atmospheric warming. Thus, knowing when and where snow is present on sea ice is crucial for understanding its role in the Arctic sea-ice system, especially as Arctic sea ice continues to thin. In this work, disparate sets of snow data are woven together to reveal the spatiotemporal patterns of snow on Arctic sea ice and to what degree atmospheric variability and sea-ice conditions influence pan-Arctic snow depth distributions. On average, springtime snow depth has decreased by -1.5 cm per decade since 1954 in the western Arctic, with geographically-varying attributions to sea-ice loss and changing snowfall. There is large year-to-year variation in snow depth within this trend, which is influenced by natural climate variability. Using a combination of reanalysis, snow model output, satellite and in situ data, we found that the Arctic Oscillation is especially impactful to snow depth variability. In summer, a positive phase of the Arctic Oscillation leads to more intense, frequent cyclones and cooler temperatures aloft, creating snowier, more reflective surface conditions. However, since the mid-2000s, summertime snow on Arctic sea ice has become less sensitive to atmospheric variability, which we attribute to the unprecedented warming in the Arctic. How snow’s role in the changing Arctic sea-ice system is discussed as future avenues of study. Bio: Dr. Webster is a research scientist who studies the role of snow and sea ice in a changing climate through observation and modeling. The scope of her work centers on sea ice and atmosphere-snow-ice-ocean interactions across spatial and temporal scales, from localized event-driven processes to regional interdecadal trends. She received her Ph.D. in Oceanography with a focus on Arctic sea ice from the University of Washington in 2016. Since then, Dr. Webster has participated in 12+ polar expeditions. She became a civil servant at NASA’s Goddard Space Flight Center in 2017, where she investigated snow and sea ice physical processes using remote sensing techniques. In 2019, Dr. Webster joined the University of Alaska Fairbanks, shifting her focus towards integrating observations more comprehensively with climate modeling. In 2023, she joined the University of Washington’s Polar Science Center, expanding her research to the Southern Hemisphere. She’s actively engaged with broader communities through public serviceand outreach, and serves as U.S. representative to the International Arctic Science Committee (IASC), chair of the Climate and Cryosphere (CliC) Arctic Sea Ice Working Group, and member of other professional societies. Dr. Webster thoroughly enjoys studying snow, sea ice, and climate and getting opportunities to share her enthusiasm for polar science with others.