Rapid disintegration of Alpine glaciers observed with satellite data

TLDR

Analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s. Using digitized glacier outlines from the 1973 inventory and Landsat TM data from 1985 to 1999, the authors measured area changes of about 930 Alpine glaciers. The study found an 18 % area loss (−1.3 % yr⁻¹) from 1985–1999, seven times the 1850–1973 mean, extrapolating to a 25 km³ volume loss since 1973, with highly variable glacier geometry suggesting rapid disintegration and a likely acceleration of retreat through positive feedbacks.

Abstract

Analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s. By using digitized glacier outlines inferred from the 1973 inventory and Landsat Thematic Mapper (TM) satellite data from 1985 to 1999, we obtained area changes of about 930 Alpine glaciers. The 18% area reduction as observed for the period 1985 to 1999 (−1.3% a −1 ) corresponds to a seven times higher loss rate compared to the 1850–1973 decadal mean. Extrapolation of area change rates and cumulative mass balances to all Alpine glaciers yields a corresponding volume loss of about 25 km 3 since 1973. Highly individual and non‐uniform changes in glacier geometry (disintegration) indicate a massive down‐wasting rather than a dynamic response to a changed climate. Our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks.