| Abstract: |
| The Highlands of Asia play the role of an ‘Asian water tower’ as they supply water and regulate the climate in upland and lowland areas of Asia adjacent to them. Despite their diversity and complexity in terms of the land and peoples across their three principal zones, viz., the highland Plateau, the upland watersheds, and the lowland plains, they present quite a uniform set of ecological and economic challenges. <\br><\br>
Land degradation, one big challenge in the Highlands of Asia, is quite possibly the main environmental issue worldwide. While erosion is a natural process and different erosive processes have helped to shape the earth’s land surface over millions of years, in places human interference and action have increased the land degradation potential and affected infrastructure and the lives of millions of people. Land degradation negatively affects the livelihoods and food security of local people – poor people in particular - in the upstream areas through degradation of the natural resource base. Downstream, the sediment loads resulting from widespread erosion leads to reduced life spans of reservoirs, abrasion of hydro-electrical equipment in hydropower stations, increased flood risk due to increased riverbed levels and other infrastructural problems. On the Tibetan Plateau – located at the heart of the Highlands of Asia with extremely low precipitation and very high evaporation rates in the West, and excessive rainfall and temperate climate in the South East - a number of different degradation processes can be observed, be they wind erosion, water erosion, or mass movements. These processes are responsible for some of the highest sediment loads in the rivers originating on the plateau and extended areas that have fallen prey to desertification. To what extent these processes are human induced is still subject to scientific research. Sediments are believed to be from human induced erosion by forest clearing and intensified grazing. Desertification as a result of excessive pressure on grasslands and low water availabilities has further claimed good and productive areas. These areas provide little more than sediment sources nowadays and directly affect the food security of nomadic herders.
Over the past decades temperatures on the Highlands have increased by 0.16 and 0.32 degrees Celsius per decade for annual and winter temperatures, respectively. This resulted in the decrease of permafrost, destabilizing many areas on the Highlands. Glaciers were observed to melt faster than in the years before. This increasing trend is projected to continue significantly with the currently observed trends of global climate change. At the same time precipitation mainly in the winter was also observed to increase and is further projected to increase. However, due to increased temperatures, less precipitation is expected to fall as snow resulting in reduced snow cover and volume. Earlier thawing of snow cover well in advance of the spring season may result in severe spring droughts. With the projected scenarios for temperature and precipitation trends, natural vegetation zones on the Highlands will change substantially. The temperate grassland and cold temperate coniferous forest areas
could expand and temperate as well as ice-edge deserts may shrink. These changes may result in a shift
of the boundary of the farming-pastoral transition region and provide favourable conditions for livestock production. However, this transition zone is also in the area of potential desertification and serious consequences may occur if protection measures are not taken. |
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