Glacier fluctuations and climate change detection

Abstract

Observed glacier fluctuations contribute important information about rates of change in energy fluxes at the earth/atmosphere-interface, possible acceleration trends in the development and the range of pre-industrial variability. Both, the mass balance as the direct, undelayed signal as well as the cumulative length change as a clear but indirect, delayed, filtered and strongly enhanced signal, have a remarkable memory function and should be used in combination for worldwide glacier monitoring in view to climate change detection.
Mean annual mass losses measured for the period 1980-1993 on 35 glaciers in 11 mountain ranges of North America, Eurasia and Africa are close to three decimeters water equivalent. This amount reflects an additional energy flux of about 3 W/m² and roughly corresponds to the estimated man-induced radiative forcing. In the European Alps, the directly measured glacier mass balances during 1980-1990 were especially negative and comparison with holocene records of cumulative glacier length changes as reconstructed from moraine investigations indicates that the «warm» limit of the pre-industrial variability range is now reached at least with respect to the past about 5,000 years.