Oceanic response to changes in the WAIS and astronomical forcing during the MIS31 superinterglacial
Flavio Justino1, Douglas Lindemann1, Fred Kucharski2, Aaron Wilson3, David Bromwich3, and Frode Stordal41Department of Agricultural Engineering, Universidade Federal de Vicosa, PH Rolfs, Vicosa, Brazil 2The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy 3Polar Meteorology Group, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH, USA 4University of Oslo,Department of Geosciences, Forskningsparken Gaustadalleen, Oslo, Norway
Received: 08 Nov 2016 – Accepted for review: 18 Nov 2016 – Discussion started: 24 Nov 2016
Abstract. Marine Isotope Stage 31 (MIS31, between 1085 ka and 1055 ka) was characterized by higher extratropical air temperatures and a substantial recession of polar glaciers compared to today. Paleoreconstructions and modeling efforts have increased the understanding of MIS31 interval, but questions remain regarding the role of the Atlantic and Pacific Oceans in modifying climate anomalies associated with the variations in Earth’s orbital parameters. Based on multi-century coupled climate simulations, it is shown that under the astronomical configuration of the MIS31 and forced by modified West Antarctic Ice Sheet (WAIS) topography, there exists a substantial increase in the thermohaline flux and its associated northward oceanic heat transport (OHT) in both the Atlantic and Pacific Oceans. In the Atlantic, these changes are driven by enhanced oceanic heat loss to the atmosphere and increased water density. In the Pacific, anomalous wind-driven circulation in concert with stronger meridional overturning circulation results in greater northward OHT that contributes up to 85 % of the global OHT anomalies, adding to an overall reduction in sea ice in the Northern Hemisphere (NH) due to Earth’s astronomical configuration at the time. Sea-ice changes in the Southern Hemisphere (SH) are highlighted by decreased (increased) cover in Ross (Weddell) Sea.
Justino, F., Lindemann, D., Kucharski, F., Wilson, A., Bromwich, D., and Stordal, F.: Oceanic response to changes in the WAIS and astronomical forcing during the MIS31 superinterglacial, Clim. Past Discuss., doi:10.5194/cp-2016-113, in review, 2016.