Satellite observations from 2001 to 2017 reveal a strikingly prominent vegetation greening in parts of China due to the large-scale environmental conservation programs and the ecological civilization construction. Adequate assessing the climatic impact due to the greening is imperative. However, previous studies using global models with coarse resolutions did not identify significant summer impact caused by the greening.

A cooperation study from Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences and University of California, Los Angeles quantified for the first time the East Asian regional climatic impacts of the satellite-observed greening by coupling the Weather Research and Forecasting (WRF) regional climate model and Simplified Simple Biosphere model (SSiB) land surface model. The study was published online in Science Bulletin.

The WRF is the state-of-the-art regional climate model and the SSiB model has been widely used to simulate the interactions between the land surface and atmosphere. The satellite observed leaf area index and fraction of vegetation cover for 2001-2005 and 2013-2017 were used to describe the control and vegetation greening scenarios, respectively. The two scenarios simulation was integrated from 2006 to 2017.

Firstly, significant summer cooling was observed due to the vegetation greening, particularly in North China, with the air temperature decreasing by 0.41 ℃, indicating the greening lessened the global warming there.

Secondly, the observed greening mitigated the summer "north drought with south flood" anomalies in China. The simulated precipitation significantly increased in North China (0.34mm/d), while decreasing to the south of the Yangtze River (-0.14mm/d).

The enhanced surface evaporation due to reforestation and subsequent latent heat release at mid-troposphere in North China generated relative cyclone circulation and moisture flux convergence there, meanwhile, induced an anticyclone to the south, contributing to changes in summer monsoon precipitation.

"The results also suggest that the large scale plantation would not cause a water resource problem induced by increased evapotranspiration. For some semiarid areas with stable atmospheric layers, proper selection of vegetation species for reforestation or artificial precipitation may be needed." said Dr. Yu Lingxue, first author of the paper.

Dr. Yu Lingxue

Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences

Tel:+86-431-85542335

E-mail: yulingxue@iga.ac.cn

Web: http://english.iga.cas.cn/