The Roosevelt Island Climate Evolution (RICE) Project – Did the Ross Ice Shelf Collapse During MIS 5e?

Wednesday, 17 December 2014: 8:45 AM
Nancy A.N. Bertler1,2, Howard Conway3, Dorthe Dahl-Jensen4, Thomas Blunier4, Edward Brook5, Ruzica Dadic1, Barbara Delmonte6, Zhang Dongqi7, Ross Edwards8, Daniel B. Emanuelsson1,2, T. J. Fudge3, Nicholas Golledge1,2, Richard C A Hindmarsh9, Robert L Hawley10, Sepp Kipfstuhl11, Helle Astrid Kjær4, Andrei Kurbatov12, James Lee5, Paul Andrew Mayewski12, Timothy Naish1,2, Peter D Neff1,2, Reed P Scherer13, Jeffrey P Severinghaus14, Marius Folden Simonsen4, Eric J. Steig15, Andrea Tuohy1,2, Paul Travis Vallelonga4 and Edwin D Waddington15, (1)Victoria University of Wellington, Antarctic Research Centre, Wellington, New Zealand, (2)GNS Science-Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand, (3)Univ Washington, Seattle, WA, United States, (4)Niels Bohr Institute - University of Copenhagen, Copenhagen, Denmark, (5)Oregon State University, College of Earth, Ocean and Atmospheric Sciences, Corvallis, OR, United States, (6)University of Milano-Bicocca, Department of Earth and Environmental Sciences, Milano, Italy, (7)Chinese Academy of Sciences, Key Laboratory of Cryosphere and Environment, Beijing, China, (8)Curtin University, Department of Imaging and Applied Physics, Perth, Australia, (9)NERC British Antarctic Survey, Cambridge, CB3, United Kingdom, (10)Dartmouth College, Hanover, NH, United States, (11)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (12)University of Maine, Climate Change Institute, Orono, ME, United States, (13)Northern Illinois Univ, De Kalb, IL, United States, (14)Scripps Institution of Oceanography, Solana Beach, CA, United States, (15)University of Washington, Seattle, WA, United States
Geological evidence and modelling experiments suggest that the removal of ice shelves from marine based ice sheets can lead to catastrophic collapse. Roosevelt and Ross Islands are thought to be key stabilization anchors for the Ross Ice Shelf and thus the West Antarctic Ice Sheet.

As part of the Roosevelt Island Climate Evolution (RICE) project, a 763m deep ice core was recovered during 2011-2013 from Roosevelt Island, at the northern edge of the Ross Ice Shelf. The ice at Roosevelt Island is grounded 210m below sea level and accumulates in situ, with the Ross Ice Shelf flowing around the rise. High resolution radar surveys show a well developed Raymond Bump at the divide of the ice dome. With the conclusion of the RICE core processing campaign in July 2014, a preliminary age model is developed using annual layer count, volcanic ash layers; and high resolution methane data tied to the WAIS Divide ice core record, and a glacial flow model.

Here we show preliminary data spanning over 100 ka including evidence of ice from the Eemian period (MIS 5e) at the base of the core. The presence of Eemian ice in the RICE record raises the question: how much of the Ross Ice Shelf and West Antarctic Ice Sheet collapsed during the last interglacial, when global sea level was 4-8m higher than today? We discuss reconstructions of sea surface and air temperature, sea ice extent, atmospheric circulation patterns, and ice shelf retreat. An ensemble of sensitivity modelling experiments is used to determine thresholds for the removal of ice on Roosevelt Island and correlated grounding line and ice volume changes of the Ross Ice Shelf and the West Antarctic Ice Sheet.