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Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
The Contribution of Alaska's Glaciers to Global Sea Level Rise
Keith Echelmeyer1, William Harrison2, Craig Lingle3, Martin Truffer4, Anthony Arendt5, Virginia Valentine6, Sandy Zirnheld7
1Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Dr, Fairbanks, AK, 99775-7320, USA, Phone 907-474-5359, Fax 907-474-7290, truffer@gi.alaska.edu
2Geophysical Institute, University of Alaska Fairbanks, PO Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7706, Fax 907-474-7125, harrison@gi.alaska.edu
3Geophysical Institute, University of Alaska Fairbanks, PO Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7679, Fax 907-474-7290, craig.lingle@asf.alaska.edu
4Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK, 99775-7320, USA, Phone 907-474-5359, Fax 907-474-7290, truffer@gi.alaska.edu
5Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7146, Fax 907-474-7290, anthony.arendt@gi.alaska.edu
6Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7455, Fax 907-474-7290, by@gi.alaska.edu
7Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7455, Fax 907-474-7290, slz2gi.alaska.edu
We have used laser altimetry to measure surface profiles of almost 100 glaciers in Alaska and northwestern Canada. To date, 72 of these glacier profiles have been compared to USGS maps from the 1950s to calculate volume changes. The measured glaciers were grouped into seven regions, and volume changes extrapolated to all glaciers in these regions. All of the glacierized areas of Alaska are accounted for in the extrapolation. Data reduced so far show an average thickness change of -0.5 m a-1, or 0.14±0.04 mm a-1 sea level equivalent for the period from the 1950s to mid 1990s. Repeat profiles of 48 glaciers between the mid-1990s and 2000/01 suggest that the thinning rate has almost doubled in recent years. Our estimates represent the largest glaciological contribution to sea level rise yet measured.
Preliminary work on the effect of climate change on glacier mass balance shows that measured glacier changes can be explained by a summer warming of about 0.7°C, a value slightly greater than the observed temperature change of 0.4°C. We will discuss ways in which we are working to improve the definition of regions used in this study, the extrapolation from single glaciers to entire regions, and the extrapolation of thickness change along one or a few profiles to an entire glacier. We will also discuss 'abnormal' glaciers, such as surging and tidewater glaciers, and remnant ice fields. Many tidewater glaciers have undergone rapid retreats in the past century at a rate that is not typical for terrestrial glaciers of the same region. On the other hand, there are a few advancing tidewater glaciers surrounded by terrestrial glaciers with strongly negative mass balances.
Abstract Categories: Changes on Land
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