Cryospheric and Polar Processes Seminar: Joseph A. MacGregor

A Synthesis of the Thermal State of the Bed of the Greenland Ice Sheet

By Joseph A. MacGregor, Ph.D. - Research Associate, Institute for Geophysics, The University of Texas at Austin

The present thermal state of an ice sheet’s bed (frozen or thawed) is an important control upon its history, present dynamics and future vulnerability to climate change. However, this thermal state can only be observed directly within sparse boreholes or simply inferred from the presence of subglacial lakes. In this talk, I'll synthesize new and existing spatially extensive inferences of the thermal state of the bed of the Greenland Ice Sheet to better constrain this state, identify poorly constrained regions and inform ice-flow modeling. New remote sensing inferences are derived from this ice sheet’s deep radiostratigraphy, MODIS surface imagery and InSAR surface velocity. Existing inferences include outputs from multiple thermomechanical ice-flow models. I evaluate their agreement and present a ice-sheet-wide mask that synthesizes our current understanding of the thermal state of bed of the Greenland Ice Sheet.