Glacier terminus fluctuations on Mount Baker, Washington, USA, 1940- 1990, and climatic variations

The terminus positions of six glaciers located on Mount Baker, Washington, were mapped by photogrammetric techniques at 2- to 7-yr intervals for the period 1940-1990. Although the timing varied slightly, each of the glaciers experienced a similar fluctuation sequence consisting of three phases: 1) rapid retreat, beginning prior to 1940 and lasting through the late 1940s to early 1950s; 2) approximately 30 yr of advance, ending in the late 1970s to early 1980s; 3) retreat through 1990. Terminus positions changed by up to 750 m during phases, with the advance phase increasing the lengths of glaciers by 13 to 24%. These fluctuations are well explained by variations in a smoothed time-series of accumulation-season precipitation and ablation-season mean temperature. The study glacier appear to respond to interannual scale changes in climate within 20 yr or less. -from Author