Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the mid-Pliocene Warm Period
- 1School of Earth and Environment, Earth and Environment Building, University of Leeds, Leeds, LS2 9JT, UK
- 2British Geological Survey, Keyworth, Nottingham, UK
- 3Department of Geosciences, University of Massachusetts, 611 N. Pleasant St, Amherst, MA 01003, USA
- 4National Center for Atmospheric Research, Boulder, Colorado, USA
- 5Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan
- 6Research Institute for Global Change, JAMSTEC, Yokohama, Japan
- 7School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK
- 8Columbia University – NASA/GISS, New York, NY, USA
- 9Aix-Marseille Université, CNRS, IRD, CEREGE UM34, 13545 Aix-en-Provence, France
- 10Sorbonne Universités, UPMC Univ Paris 06, UMR 7619, Metis, 75005, Paris, France
- 11Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
- 12Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
- 13Laboratoire des Sciences du Climat et de l'Environnement, Saclay, France
- 14Bjerknes Centre for Climate Research, Uni Research Climate, Bergen, Norway
- 15Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
Abstract. During an interval of the Late Pliocene, referred to here as the mid-Pliocene Warm Period (mPWP; 3.264 to 3.025 million years ago), global mean temperature was similar to that predicted for the end of this century, and atmospheric carbon dioxide concentrations were higher than pre-industrial levels. Sea level was also higher than today, implying a significant reduction in the extent of the ice sheets. Thus, the mPWP provides a natural laboratory in which to investigate the long-term response of the Earth's ice sheets and sea level in a warmer-than-present-day world.
At present, our understanding of the Greenland ice sheet during the mPWP is generally based upon predictions using single climate and ice sheet models. Therefore, it is essential that the model dependency of these results is assessed. The Pliocene Model Intercomparison Project (PlioMIP) has brought together nine international modelling groups to simulate the warm climate of the Pliocene. Here we use the climatological fields derived from the results of the 15 PlioMIP climate models to force an offline ice sheet model.
We show that mPWP ice sheet reconstructions are highly dependent upon the forcing climatology used, with Greenland reconstructions ranging from an ice-free state to a near-modern ice sheet. An analysis of the surface albedo variability between the climate models over Greenland offers insights into the drivers of inter-model differences. As we demonstrate that the climate model dependency of our results is high, we highlight the necessity of data-based constraints of ice extent in developing our understanding of the mPWP Greenland ice sheet.