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Tim Bartholomaus, University of Idaho. Glaciology. "Understanding fast glacier change: Revealing the processes at glacier beds and tidewater glacier termini"
WhenThursday, Jan 4, 2018, 3:30 – 5 p.m.
WhereJHN 075
Campus room075
Event typesLectures/Seminars
Description

Glaciers and ice sheets worldwide are experiencing rapid changes to their velocities and thicknesses that were almost entirely unexpected just 15 years ago. These changes motivate new examinations of the processes governing glacier and ice sheet mass balance and dynamics. Improved understanding of glaciological processes informs more sophisticated ice flow models and ultimately reduces the uncertainty associated with projections of sea level rise. In this talk, I will describe recent progress in understanding the processes at glacier beds and at tidewater glacier termini. I use a variety of in situ and remotely sensed data, including glacier seismology, to reveal subglacial hydrology and its impact on glacier motion, iceberg calving, sliding over till beds, and the controls on upstream thinning. Variations in background seismic tremor amplitude allows the reconstruction of subglacial hydrographs whose source locations and geometry can be tracked. Seismically impulsive icequakes reveal the tidal and submarine melt influences on iceberg calving. Two dimensional Fourier transforms of former ice stream beds indicate self-organized processes and pattern formation at the ice-till interface. Steep, thin reaches of ice sheet outlet glaciers, formed over millions of years of glacier erosion, represent a stabilizing influence on upstream, interior ice. Together, these studies enable a more complete understanding of the processes controlling fast glacier change.

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