全球气候变化对干旱区影响分析

Analysis of the Impact of Global Climate Change on Dryland Areas

干旱区约占地球陆地面积的41%,养育了世界上超过38%的人口,是大多数发展中国家和贫困人口的聚集地,也是全球气候变化影响和响应最敏感的地区之一,对其气候、水文和生态环境变化开展研究是十分必要的。近几十年来相关研究不少,但结论比较零散,也有很多不一致的地方。基于对国内外文献的分析,归纳梳理了气候变化下干旱区的气候、水文、面积和类型的变化及其这些变化对生态系统的影响。梳理的主要结果如下:干旱区CO_(2)排量约为湿润区的30%,但升温速率却比湿润区高20%~40%。在过去的半个多世纪,干旱区面积增加了约2.61×10^(6) km^(2),预计21世纪末,全球干旱区面积将继续扩大约5.8×10^(6) km^(2),占陆地总面积的一半以上。在全球变暖背景下,干旱区中以降水和冰雪融水补给为基础的水资源系统将会更为脆弱,冰、雪等水文要素及水资源构成发生改变,水文波动加大,水资源不确定性加剧。伴随干旱区面积扩大和干旱程度增加,干旱区水资源短缺、水体面积萎缩、生态系统退化、荒漠化程度也随之加剧,未来干旱区社会经济发展和生态安全保障将面临更严峻的挑战。这些归纳梳理所凝练出的一些综合性结论,对政府决策以及未来提出可信明确的科学认识具有一定的参考意义。

Drylands cover about 41%of the Earth's land area,support more than 38%of the world's population,and are home to most of the world's developing and poor populations.Drylands are one of the most sensitive areas to the impacts and responses to global climate change,and it is essential to study the changes in their climate,hydrology and ecological environment.There have been many studies in this area in recent decades,but the conclusions are fragmented and there are many inconsistencies.Based on the analysis of domestic and international literature,this paper summarizes and composes the changes in climate,hydrology,area and type of drylands under climate change and the impacts of these changes on ecosystems.The main results of the combing are as follows.CO_(2) emissions from dryland are only about 30%of those from humid areas,but the warming rate is 20%~40%higher than that of humid areas.In the past half century,the dryland area has increased by about 2.61×10^(6) km^(2),and by the end of this century,the global dryland area will continue to expand by about 5.8×10^(6) km^(2),which will occupy more than half of the total land area.Under the background of global warming,the water resources system based on precipitation and snow melt recharge in drylands will be more fragile,and hydrological elements such as ice and snow and water resources composition will change,hydrological fluctuations will increase,and water resources uncertainty will intensify.Along with the expansion of dryland area and the increase of aridity,the shortage of water resources,shrinkage of water bodies,degradation of ecosystems and desertification in dryland areas will also intensify,and the future socio-economic development and ecological security of dryland areas will face more severe challenges.Some comprehensive conclusions condensed from these inductive combs are of reference significance for governmental decision making and for proposing credible and clear scientific understanding in the future.