Abstract : 1C.29
Climate change information as derived from long-term measurements of winter and summer glacier mass balance

Heidi Escher-Vetter
Commission for Glaciology, Bavarian Academy of Sciences and Humanities

Glacier annual mass balance data (bn) from nearly all regions of the world clearly show the wasting of the ice masses over the last decades and are therefore considered as good indicators of climate change. The separate determination of winter (bw) and summer (bs) balance, however, enables a better analysis of the driving climatological factors, i.e. air temperature as a proxy for the energy balance governing the ablation processes, and solid precipitation as the source of accumulation. bn is or has been determined over longer or shorter periods for close to 300 glaciers worldwide, but bw and bs values are only available for approx. 50 glaciers, a majority of them lying in Scandinavia. For alpine glaciers, this data set is provided for just a few glaciers. One of them is the Vernagtferner, Oetztal, Austria, where bn, bw, and bs = bn - bw are determined with the direct glaciological method annually since 1964/65. Other alpine glaciers with comparable records are, for instance, the Glacier de Sarennes (France), the Hintereisferner (Oetztal, Austria), the Wurtenkees (Sonnblick, Austria), and the Fontana bianca glacier (WeiƟbrunnferner, Italy), although the latter two comprise much shorter periods than the other glaciers. A main result of the analysis is that winter precipitation has not changed much over the last forty years on Vernagtferner, and thus, the annual net mass balance is dominated by the weather conditions during the ablation season. Some Scandinavian glaciers show a slightly different behaviour, which will also be discussed in terms of their climatological relevance.