|The role of ice stream dynamics in deglaciation|
|investigators:||A. Robel and E. Tziperman|
|journal:||JGR Earth Surface|
Does the presence of ice streams enhance deglaciation? If so, this should render certain large ice sheets, those with geometry and basal properties conducive to stream formation, more sensitive to changes in the climatic mass balance input. Based on an idealized PISM configuration, the simulations in this study show that when the ice sheet is large and ice streams are sufficiently developed an upward shift in equilibrium line altitude results in rapid deglaciation, while the same shift applied to an ice sheet without fully-formed ice streams results in continued ice sheet growth or slower deglaciation. Rapid deglaciation in ice sheets with significant streaming behavior is caused by ice stream acceleration and the attendant enhancement of calving and surface melting at low elevations. Ice stream acceleration is ultimately the result of steepening of the ice surface and increased driving stresses in ice stream onset zones, which come about due to the dependence of surface mass balance on elevation.
The core team at UAF continues to support PISM users. The new email for help is email@example.com; it replaces firstname.lastname@example.org. As before, email to this address will be distributed to all the UAF developers, and so it will get the most prompt response year-round.
The 4000 square km ice field in Southeast Alaska is well-known and accessible since its outlets are in the suburbs of the Alaska state capital, Juneau. But climate data for the area are sparse.
Those model runs that agreed well with observations for 1971 to 2010 generated volume and area losses of more than half by 2099. While co-author Regine Hock (UAF) is quoted as saying “The massive icefield that feeds Alaska’s Mendenhall Glacier may be gone by 2200 if warming trend predictions hold true,”, the authors emphasize that spatially-distributed mass balance measurements and improved climate projections that resolve the local temperature and precipitation patterns are essential to solidifying these predictions.
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