Potential Impact of Climatic Change and Human Activities on Desertification in China

Climatic change and desertification are two of notable global environmental issues,which have been paid a good deal of attention by scientists.As one of the countries with relatively large areas of desert and desertified land in the world,China has 263.62×10~(4) km~(2) desertified land and 173.97×10~(4) km~(2)sandy desertified land,accounting for 27.46% and 18.12% of the total land territory respectively.Since the foundation of the PRC in 1949,Chinese government has attached great importance to combating desertification and made great progress.However,desertification in China developed fast under the effects of climatic change and human activities.Before 1999,the trend of desertification in China is expanding and speeding up as a whole,but rehabilitating in some partial area.On the basis of the survey for the typical grassland and desert-oasis region,the expanding speed of desertified land is 1 560 km~(2) per year from the later of 1950s to mid-1970s,2 100 km~(2) per year from the mid-1970s to mid-1980s,about 2 400 km~(2) per year from the mid-1980s to early 1990s,and the annual expanding speed of desertified land is up to 3 436 km~(2) during 1994-1999 based on the second national survey of desertification.After 1999,the situation of desertification in China has a significant change,i.e.the area of desertified land gradually decreased,and desertification development represented obvious reverse trend.The result of the third national desertification survey shows that annual decrease area of sandy desertified land is 1 283 km~(2) during 1999-2004 period.The reason for the change should be attributed to the interaction of climatic change and human activities.The climate change,in particular the precipitation change in northern China and intensive human activities in the future could exert far-reaching impacts on desertification.The warm-drying trend might speed up desertification development,but regionally precipitation increasing could be in favor of the reverse of desertification.Human activities have positive or negative effects on desertification.Therefore,to control desertification measures should be taken to adapt and mitigate the effects of warm-drying climate,and to eliminate negative impacts from human activities,and to rehabilitate desertified land actively.