NEWS: PISM at AGU 2014
The Parallel Ice Sheet Model pism0.6 is an open source, parallel, high-resolution ice sheet model. Features:
|Testing the sensitivity of the East Antarctic Ice Sheet to Southern Ocean dynamics: past changes and future implications|
|investigators:||C. Fogwill, C. Turney, K. Meissner, N. Golledge, P. Spence, J. Roberts, M. England, R. Jones, and L. Carter|
|journal:||Journal of Quaternary Science|
The stability of the Antarctic ice sheet and its contribution to sea level under projected future warming remains highly uncertain. The Last Interglacial (LI; 135–116 ka ago) is a potential analogue for the present period, with sea levels 6.6–9.4 m higher than present, and thus it deserves study. This paper examines a possible source of LI sea-level rise. These authors report on model simulations exploring the effects of migrating Southern Hemisphere Westerlies (SHWs) on Southern Ocean circulation and Antarctic ice-sheet dynamics. The effect on ice dynamics is modeled with PISM, which plays only a supporting role in this work. They conclude that southerly shifts in winds may have significantly impacted the sub-polar gyres, inducing pervasive warming of 0.2–0.8 °C in the upper 1200 m adjacent to sectors of the East Antarctic Ice Sheet (EAIS). Thus the EAIS potentially made a substantial, hitherto unsuspected, contribution to LI sea levels.
In a new Nature Communications paper, researchers at Victoria University and the University of New South Wales describe a model study of Antarctic ice sheet evolution over the last 25 kyr using PISM with ocean-forcing inputs from the Earth system model LOVECLIM. They show that when the ocean around Antarctica becomes more stratified, warm water at depth melts the ice sheet faster than when the ocean is less stratified.
The study used a large ensemble of 15 km PISM simulations in a data-constrained mode. In the simulations that best fit a variety of temporal and spatial observations, several episodes of accelerated ice-sheet recession occurred, with the timing of the largest being coincident with meltwater pulse 1A. This episode saw an abrupt rise in global sea level, with an Antarctic contribution of nearly three meters over just a few centuries.
PISM is jointly developed at the University of Alaska, Fairbanks (UAF) and the Potsdam Institute for Climate Impact Research (PIK). UAF developers, who are in the Glaciers Group at the GI, are supported by NASA's Modeling, Analysis, and Prediction and Cryospheric Sciences Programs (grants NAG5-11371, NNX09AJ38C, NNX13AM16G, NNX13AK27G) and by the Arctic Region Supercomputing Center.