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 studies have focused on carbon cycle and greenhouse gas emissions, 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. The biophysical effects of wetland change on climate in China remain unclear.
A study led by Prof. JIANG Ming from the Northeast Institute of Geography and Agroecology of the Chinese Academy of Sciences quantified for the first time the biophysical effects of marshland loss on surface temperature in China based on satellite measurements of land surface temperature. The study was published online in Geophysical Research Letters.
Based on satellite measurements of land surface temperature (LST) and observed air temperatures during 2003-2014, the researchers 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.
SHEN Xiangjin
Northeast Institute of Geography and Agroecology
E-mail: shenxiangjin@iga.ac.cn
Chinese researchers have discovered that the reduction of marshland could increase the land surface temperature. The researchers hoped to find out the biophysical effects of wetland, which plays an important role in local, regional and global climate change.
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