Progress in Semi-arid Climate Change Studies in China

Abstract

This article reviews recent progress in semi-arid climate change research in China. Results indicate that the areas of semi-arid regions have increased rapidly during recent years in China, with an increase of 33% during 1994–2008 compared to 1948–62. Studies have found that the expansion rate of semi-arid areas over China is nearly 10 times higher than that of arid and sub-humid areas, and is mainly transformed from sub-humid/humid regions. Meanwhile, the greatest warming during the past 100 years has been observed over semi-arid regions in China, and mainly induced by radiatively forced processes. The intensity of the regional temperature response over semi-arid regions has been amplified by land-atmosphere interactions and human activities. The decadal climate variation in semi-arid regions is modulated by oceanic oscillations, which induce land-sea and north-south thermal contrasts and affect the intensities of westerlies, planetary waves and blocking frequencies. In addition, the drier climates in semi-arid regions across China are also associated with the weakened East Asian summer monsoon in recent years. Moreover, dust aerosols in semi-arid regions may have altered precipitation by affecting the local energy and hydrological cycles. Finally, semi-arid regions in China are projected to continuously expand in the 21st century, which will increase the risk of desertification in the near future.

摘要

本文回顾了中国半干旱气候变化的最新研究进展.以往研究表明,近些年我国半干旱区面积显著增长,相对于1948-1962年,1994-2008年其面积增长了33%.研究发现我国半干旱区的扩张速度是干旱和半湿润地区的近10倍,其扩张主要由半湿润、湿润区转干而来.同时,近100年我国半干旱区出现了强化增温,主要由辐射强迫过程引起.陆-气相互作用和人类活动放大了半干旱区局地温度响应强度.而海-气相互作用通过改变海-陆和南-北热力差异,进而影响西风带、行星波和阻塞频率的强度,从而调制半干旱区年代际尺度的气候变化.此外,近些年我国半干旱区的气候变干与东亚夏季风减弱有关.此外,半干旱区的沙尘气溶胶也能通过影响局地能量和水循环从而改变降水.最后,我国半干旱区将在21世纪持续扩张,这将增加未来沙漠化的风险.