Climate Variation Feature and Its Effect on Environment Change in Central Tibet from 1961 to 2000

Climate change is a global issue. It's very difficult to distinguish the climatic impacts from the variation of atmospheric constituents by human activities among human activities influences on climate. In order to demonstrate the environmental effect over Tibetan agricultural integrated development area (central Tibet) from 1990 to 2000, using meteorological factors such as precipitation, temperature, evaporation, accumulated days of gale and sandstorm in the recent 40 years and environmental integrated assessment index, it investigates the variation of regional climate feature and the environmental effects over Tibetan agricultural integrated development area.The analysis shows that the annual temperatures and precipitation exhibit increasing tendency over central Tibet, the annual mean temperature increases 0.24 ℃/10a; the precipitation decreases 2.9 mm in the earlier 20 years, but it shows distinct increasing tendency from 1981 to 2000 and the average increase is 9.6 mm/a; evaporation quantity, strong wind days and sandstorm days exhibit decreasing trend. In the target region, the evaporation quantity decreases averagely 24.4 mm/10a before 1983, and then decreases 22.1 mm/a; the accumulated days of gale present a decreased tendency, with the average of 3 d/a from 1990s. In the same way, the accumulated days of sandstorm has decreased 1—2 d/a, in which Zedang station has no record of sandstorm after 1995. Comparing with the earlier 30 years, the sandstorm days decrease by 22—31 d in 1990s.Considering arid and semi-arid river valley area, the variation trend of warm and humid climate is beneficial to environment improvement, the regional integrated environmental assessment index increases 5.24% during 1990—2000. But natural environment lose and desertification are getting worse because of the frequent natural disasters like flood, hail and human activities. Especially human activities accelerate the development of land desertification. The main problem is that human activities such as farmland expansion and deforestation caused by the population growth and the lack of fuel material, over breeding of livestock, which lead to the expanding of bare land and the acceleration of soil erosion in the remote area far from the river valley. Facing the vulnerable environment, with the strict controlling of the population growth, it is a powerful approach of agricultural integrated development and an important act to achieve the goal of sustainable development of region's society and economy that the government ought to actively adjust the structure, develop highly effective and advanced industry, attempt to strengthen the ability of the exploitation of renewable energy such as wind and solar energy.