CHANGES OF GLACIERS IN GLACIER BAY, ALASKA, USING GROUND AND SATELLITE MEASUREMENTS

The deglaciation of Glacier Bay, Alaska is studied using historical maps, field measurements, and satellite imagery. In general, both tidewater and non-tidewater glaciers in the area have receded during the last century, but the rates of recession are quite variable, especially in the case of the tidewater glaciers. Available average air temperature data from nearby meteorological stations show a general warming trend, especially over the last 20 years. Such a warming trend may help to explain recession of the non-tidewater glaciers of the area. Comparison of September Landsat multispectral scanner imagery from 1973 and 1986 shows that the amount of vegetation increased significantly and rapidly as glaciers receded. The vegetation within a Landsat subscene covering Muir Inlet increased about 86% during the 13-year period. The once-impressive Muir Glacier, a tidewater glacier, has receded dramatically since the late 1800s. Satellite measurements show that the terminus retreated > 7.3 km between 1973 and 1992. Work accomplished by researchers earlier in this century has been extended using satellite techniques, allowing us to study glacier changes quantitatively in the entire Glacier Bay region over the past two centuries.