NEWS: PISM at AGU 2014
The Parallel Ice Sheet Model pism0.6 is an open source, parallel, high-resolution ice sheet model. Features:
Three cross sections (north, center, south) through the modeled initial states, at a 5 km resolution. Click the image to go to Journal of Glaciology journal.
|Role of model initialization for projections of 21st-century Greenland ice sheet mass loss|
|investigators:||G. Adalgeirsdottir and 6 others|
This paper assesses the sensitivity of projections of Greenland ice sheet contribution to 21st-century sea-level rise to the model initial state. Four initialization methods are applied using PISM. The simulated contribution to sea-level rise by 2100 ranges from an equivalent of 0.2 to 6.8 cm. The largest uncertainties arise from different formulations of the regional climate models (0.8–3.9 cm) and applied scenarios (0.65–1.9 cm), but an important source of uncertainty is the initialization method (0.1–0.8 cm). These model simulations do not account for the recently observed acceleration of outlet glaciers and consequent thinning rates, ocean forcing, or the feedback occurring between ice-sheet elevation changes and climate forcing. These results should be considered a lower limit of Greenland ice sheet contributions to sea-level rise, until such processes have been integrated into large-scale ice-sheet models.
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.
In a Geoscientific Model Development Discussion paper, UAF author Ed Bueler and IMAU author Ward Van Pelt describe PISM's new mass conserving subglacial hydrology models.
For the PISM user with an interest in subglacial hydrology this paper provides a detailed description of all the subglacial hydrology models available in PISM versions v0.6 and above, along with a stability analysis, verification, and an application to the Greenland ice sheet.
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.