Wetlands cover approximately 6% of the Earth's land surface, which play an important role in local, regional and global climate change. Regarding the study of the effects of wetland change on climate, most previous studies focused on carbon cycle and greenhouse gas emissions of wetlands, ignoring the biophysical impacts which in some cases can offset the biogeochemical effects.

China has the third largest area of marshland in the world. Due to the effects of human activities, marshland in China has been widely converted to built-up land and cultivated land during the past decades. Until recently, the biophysical effects of wetland change on climate in China remain unclear.

A study led by Prof. JIANG Ming from the Northeast the Institute of Geography and Agroecology, Chinese Academy of Sciences (CAS) quantifies for the first time the biophysical effects of marshland loss on surface temperature in China. The study was published online in Geophysical Research Letters on Feb. 29. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL087648

Based on satellite measurements of land surface temperature and observed air temperatures during 2003-2014, this study analyzed the biophysical effects of marshland conversion on surface temperature in China by comparing the temperature difference between marshland and adjacent built-up land and cultivated land.

The results showed that marshland conversion to built-up land will increase both the daytime and nighttime temperature in China. Conversion from marshland to cultivated land could increase the daytime temperature in most months and nighttime temperature in the non-growing season, but decrease the daytime LST from July to September and nighttime LST in the growing season. There are different effects of marshland conversion to paddy field and dry farmland on surface temperatures, particularly for the cooling effects.

Under the background of global climate change, accurately evaluating the effects of wetland change on regional and global climate is becoming more and more important for the purpose of mitigating global warming. "Our results suggest that we should pay more attention to the biophysical effects of marshland loss on surface temperature, especially considering the seasonal differences of these effects", said Dr. SHEN Xiangjin, first author of the paper.

This work was supported by the National Natural Science Foundation of China, and the National Key Research and Development Program of China.

Dr. SHEN Xiangjin, Ph.D Principal Investigator

Northeast the Institute of Geography and Agroecology, Chinese Academy of Sciences

(http://english.iga.cas.cn/)

Changchun, Jilin 130102, China

Tel: 0431-85542307

E-mail: shenxiangjin@iga.ac.cn

Keyword: Wetland; Marshland loss; Warming; Temperature; China