Аннотация:Recent fluctuations of the San Rafael Glacier contrast in timing, direction and intensity with regional trends of glacier behaviour. In this paper, a link is identified between the oscillation history, the topographic situation and variations in winter precipitation. The San Rafael Glacier is the lowest latitude tidewater glacier in the world with unusually high annual mean velocities. Since the late nineteenth century, it has retreated and advanced rapidly over a total distance of 14 km and is now 60 km2 smaller than it was 100 years ago. Retreat at up to 300 m a-1 during the 1980s halted in 1990. Since then, a slight readvance has occurred at a time of accelerated regional retreat. Calving glaciers are known to respond indirectly to climate change, but whereas some may oscillate in non-climatic, cyclical ways over decadal and century timescales, the San Rafael Glacier seems to respond rapidly to changes in precipitation. The influence of calving dynamics has, at different times, both damped and amplified the response to climate change, but the topographic geometry does not permit large-scale, non-climatic fluctuations. The Holocene record of glacier behaviour is therefore probably free of calving anomalies.
