Working Group II: Impacts, Adaptation and Vulnerability

Other reports in this collection Alpine Ecosystems

Climatic changes observed in alpine areas generally have paralleled climatic patterns in surrounding regions, with the most pronounced warming at high latitudes, in the Alps, and in Asia and the least pronounced changes in tropical alpine regions (Diaz and Bradley, 1997). Precipitation generally has increased, with the most pronounced changes in winter, leading to increased snow depth (Beniston, 1997).

Regional trends in climate have led to shrinkage of alpine and subpolar glaciers, equivalent to a 0.25 ± 0.1 mm yr-1 of sea-level change or 16% of the sea-level rise in the past 100 years (Dyurgerov and Meier, 1997). This trend has been regionally variable, with Asia contributing 45% of this sea-level rise and arctic islands an additional 18%. The net mass reduction of the alpine glaciers has been most pronounced since 1980, when regional warming was greatest.

Climatic warming observed in the Alps has been associated with upward movement of some plant taxa of 1-4 m per decade on mountaintops and loss of some taxa that formerly were restricted to high elevations (Braun-Blaunquet, 1956; Grabherr et al., 1994). In general, direct human impacts on alpine vegetation from grazing, tourism, and nitrogen deposition are so strong that climatic effects on goods and services provided by alpine ecosystems are difficult to detect (Körner, 1999). Soil carbon stocks per unit area in alpine ecosystems are only one-third as great as those in the arctic because greater topographic relief promotes greater drainage and decomposition than in the arctic (Körner, 1995b).

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