Global environmental change in mountain regions : an overview

Abstract. Mountain regions cover 20% of terrestrial land surfaces and represent one of the principle source regions for the world's hydrological Systems. Mountain regions are today under pressure as a result of human interference; climatic change could lead to an additional stress on natural and socio-economic Systems. Paleo-climatic evidence has shown that past climatic change has lead to substantial shifts in the distribution of Vegetation. If the present warming trend were to continue into the 21" Century, there would be significant impacts on ecosystems. In particular. certain species may become extinct because ot their limited capacity for migration to regions with favorable climatic and soil conditions. In most mountain regions, a warmer climate will lead to a reduction in the mass of glaciers, as well as snow-pack and permafrost. Changes in precipitation regimes may have far-reaching consequences for fresh-water supply to agriculture, tourism and hydro-power. These shifts would affect not only mountain populations, but also those living downstream from the mountains and who depend on mountain-fed water resources. The social structure of populations in the mountains of the developing world may be disrupted by environmental change, because of the impacts this change is likely to have on the natural resources essential to traditional lifestyles of mountain communities.