Role of Land Use Change in Dry/Wet Trends in China during the 20th Century

The contribution of land use change to the dry/wet trends in China during the 20th century is assessed on the basis of climate simulations of coupled models under historical and land use scenarios provided by the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The results suggest that land use change may have enhanced aridification in China during the 20th century, with a contribution of approximately one-third. For humid regions, the contribution is approximately 35.4%. Although the drying trend in semi-arid regions is significant, the influence of land use is not detectable. For the arid regions, the drying trend is not significant. The land use change scenario in China is featured by a loss of primary land and increase of pasture throughout the 20th century, from 72.7% and 12.9% of the total national land in 1901, respectively, to 36.0% and 41.9% in 2004, with the enhanced changing rate lasting into the latter half of the century. This type of land use change occurs mainly in the Qinghai-Tibetan Plateau, Mongolia, and northern Xinjiang, causing decreasing trends in both temperature and precipitation. The drying trend due to decreasing precipitation overwhelms the effect of cooling temperatures.