Understanding Ice Sheet Change: Towards improved prediction

Ginny Catania
UT Austin

Glaciers and ice sheets are sensitive indicators of the Earth’s climate, responding to both natural and anthropogenic climate change on multiple timescales. While understanding the impact of ice sheets on sea‐level rise and their role in the climate system has become increasingly important, research is limited by both a paucity of observations and a lack of understanding of physical processes that control ice flow. In Greenland, seasonal fluctuations in surface velocity indicate that surface meltwater, plentiful in the summer, is routed through the ice sheet to the bed where it can enhance basal sliding. Englacial conduits (moulins) are observed using ice‐ penetrating radar and these measurements place constraints on the location and requirements for moulin formation. Additionally, observations of internal layers coincident with moulins indicate that moulins are sometimes long‐lived and that possibly just a few of them drain most of the water available on the surface. This work, coupled to other modeling studies, suggests that the seasonal accelerations observed by many researchers have a limited impact on the mass balance of the ice sheet with further warming. In the Siple Coast region of Antarctica, ice‐penetrating radar is used to examine internal stratigraphy in the ice sheet. These data reveal paleo‐grounding lines (where ice sheets meet ice shelves) and paleo‐ice stream shear margins (lateral boundaries between fast and slow flow) in ice that is now stagnant. Reconstructing ice‐flow history in this region provides important information on the controls of the position of these flow boundaries. Additionally, since such chanconstraints on tstream system.

 

2008 Journal of Glaciology Paper (pdf)