全球变化对我国荒漠化的影响

THE IMPACT OF GLOBAL CHANGE ON DESERTIFICATION IN CHINA

本文根据当前国内外科学家们对全球变化的研究及＂联合国环境与发展大会＂的决议第１２款，＂荒漠化＂的定义，探讨全球变化对我国土地荒漠化的影响。文中利用我国７００多个气象站点３０年的平均气象资料，采用联合国环境规划署环境监测系统／全球资料数据库方案活动中心以及国际上广泛应用的Ｔｈｏｒｎｔｈｗａｉｔｅ计算ＰＥ与气候分类方法，计算和绘制了当ＣＯ_２倍增、气温升高１．５－４．５℃时我国干旱区、半干旱区及半湿润干旱区（Ａｒｉｄ，ｓｅｍｉ－ａｒｉｄａｎｄｄｒｙｓｕｂ－ｈｕｍｉｄａｒｅａｓ）分布变化的图表，同时利用我国北方１６０个气象台站近４０年连续记录的气象资料，进行滑动平均，计算和绘制了干旱、半干旱区的最近４０年来气温变暖及干湿变化的趋势图，分析了在全球变化下如果工业发展和其结构不变的情况下，未来３０－５０年我国土地荒漠化的发展趋势，为我国荒漠化监测预报和防治提供依据和对策。

The impact of global change on China's desertification discussed here is based on the following premises: ①According to general acknowledgoment of the most international researchers, if the current industral structure will remain unchanged, CO2 concentration will be doubled until 2030 and mean annual temperature will be increasing for 1. 5-4.5℃ then; ②'Desertification' caused by irrational human activities and climatic change is referred to the land degradation in arid, semi-arid and dry sub-humid areas. The analysis of China's desertification adopts UNEP's aridity index (ratio of annual precipitation to potential evapotranspiration) which ranges from 0. 05 to 0.65 excluding arctic and sub-arctic regions. The potential evapotranspiration is abtained from Thornthwaite's formula. 30 year's data of more than 700 climatological station in China have been used for calculation. The result of the analysis is as follows:(1)Under the impact of the global Change, China's arid zones will be expanded and land desertification will be developed. Currenty, China's arid, semi-arid and dry sub-humid areas cover 2.976 million square km plus extreme arid area 697 thousands square km. the total area of arid and extreme arid areas is 3.673 million square km of 38.3% of China's total area, including 2. 08 million square km of desertificated land area. After CO2 doubled and mean annual temperature increased to 4℃, China's arid area will be expanded to 4.63 million square km or 48.3% of China's total area, including 2. 67 million square km of desertification land area. The increasing rate of land desertification will be 6941 km2/year.(2) Under the impact of global change, China's arid zone, will become warmer and drier. According to the date of more than 160 climatological stations in China for 40 years. During the period of 1951-1991, the 10 years running mean temperature of arid (semi-arid and dry sub-humid) areas shows an increasing tendency since the 70ties. The 10 years running precipitation also increased since 70ties, but slowly. But, the annual mean temperature of China's arid area increased insignificantly, its winter temperature increased obviously, but the summer temperature decreased. The annual precipitation of arid area has a prominent increasing after the 70ties. The semi-arid area of China has showed a different pattern of climatic variation, its temperature increased significantly since 70ties, especially in the winter, but its precipitation reduced obviously than the 50 and 60ties.