| Summary: | This is a proposal to study both ongoing and historical changes in dynamics at the rapidly retreating Columbia Glacier, in south central coastal Alaska. Tidewater glaciers (TWGs) like Columbia Glacier terminate in the ocean and merit special attention because they exhibit some of the largest and strongly non-linear dynamic volume changes of all glaciers worldwide. In addition, most ice sheet mass loss occurs at marine-ending outlet glaciers that display dynamic instabilities very similar to TWG. Yet, the response of these glaciers to climate forcing remains very poorly understood. This proposal requests support to continue an unmatched 30-year record of observations at Columbia Glacier and to study the similarities between it and the rapidly retreating Greenland outlet glaciers. Project goals are aimed at a predictive capability for future TWG volume changes, which are a dominant constituent of global sea level rise. A variety of measurements including vertical aerial photogrammetry (and subsequent feature- tracking), terrestrial time-lapse photogrammetry, airborne radar, GPS surveying, and meteorological monitoring will provide robust constraints for both inverse and forward modeling of the stress and flow fields.
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