Glacier variability in the conterminous United States during the twentieth century

Abstract

Glaciers of the conterminous United States have been receding for the past century. Since 1900 the recession has varied from a 24 % loss in area (Mt. Rainier, Washington) to a 66 % loss in the Lewis Range of Montana. The rates of retreat are generally similar with a rapid loss in the early decades of the 20th century, slowing in the 1950s–1970s, and a resumption of rapid retreat starting in the 1990s. Decadal estimates of changes in glacier area for a subset of 31 glaciers from 1900 to 2000 are used to test a snow water equivalent model that is subsequently employed to examine the effects of temperature and precipitation variability on annual glacier area changes for these glaciers. Model results indicate that both winter precipitation and winter temperature have been important climatic factors affecting the variability of glacier variability during the 20th Century. Most of the glaciers analyzed appear to be more sensitive to temperature variability than to precipitation variability. However, precipitation variability is important, especially for high elevation glaciers. Additionally, glaciers with areas greater than 1 km2 are highly sensitive to variability in temperature.