Events

Department of Physics Seminar Series: Denis Felikson
Monday, March 11, 2019 - 3:15pm

SB1 107, 1025 SW Mill Street
Free and open to the public
Light refreshments will be served

 

Denis Felikson
Cryospheric Sciences Laboratory
NASA Goddard Space Flight Center

 

"What lies beneath: how topography underneath the Greenland Ice Sheet controls the timing and magnitude of sea-level rise"

The Greenland Ice Sheet has been losing mass at an accelerating rate since 2003, in part due to changes in ice sheet dynamics. As ocean-terminating outlet glaciers retreat, they initiate thinning that diffuses inland, causing dynamic mass loss from the ice sheet interior. Although outlet glaciers have undergone widespread retreat during the last two decades, the inland extent of thinning and, thus, the mass loss is heterogeneous between glacier catchments. Here, I show how the bed topography, over which the ice sheet flows, affects both how far inland thinning can spread and the timing of the ice mass loss in response to outlet glacier retreat. Because bed topography is heterogeneous, the inland thinning extent and the timing of mass loss varies around the ice sheet. First, I start with a linearized model of ice flow to derive a metric that identifies spatial limits to thinning as it diffuses inland. The advantage to the simplified approach is that our metric is easily calculable from observed glacier bed topography and ice thickness. Next, using higher-order numerical modeling, I validate the predicted thinning limits from the linearized model, and I investigate the timing and magnitude of glacier mass loss over the coming century. Again, heterogeneity in bed topography leads to very different response times of ice mass loss from glaciers that flow over these different bed topographies. Crucially, our results identify regions of the ice sheet that stand to lose large amounts of ice in the coming century. Computationally expensive ice sheet modeling efforts can be targeted to the most susceptible regions we have identified.  Our work suggests that lower-flux glaciers are often not discussed in literature but will be significant contributors to sea-level rise by 2100.

 

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