Published: Sep 13, 2015 by The PISM Authors
A new open-access paper by Ricarda Winkelmann and others uses PISM to address an admittedly extreme question: If all currently-attainable fossil fuel resources are converted to atmospheric greenhouse gases, what happens to the Antarctic Ice Sheet?
This paper’s model-based answer is that serious destruction of the ice sheet occurs in the first millenium, at about 3 m sea level rise per century. Such a large mass loss rate tails off in the two following millenia. The large losses come from a combination of marine-ice-sheet instability and surface elevation versus mass balance feedback, both of which are modeled effects in PISM. However, in the first century of the simulations there are the same relatively-modest AIS mass changes as seen in other recent modeling work, because dynamic losses driven by increasing ocean temperatures are partly offset by increasing snowfall.
Here is a quick methods summary, with more detail found in the paper and its supplementary material: Emission scenarios, CO2 concentrations, and global mean temperature pathways are combined in an Earth system model and then downscaled to surface and ocean temperature anomalies for Antarctica. These regional warming scenarios are then used to force PISM, in particular using its positive-degree-day scheme to model surface melt and a three-equation model for subshelf melting.
US National Public Radio featured the paper, including comments by co-author Ken Caldeira, on the 11 September edition of All Things Considered, as did the New York Times.
