Biogeophysical feedbacks of land use/cover change on climate
Shushi Peng & Shilong Piao
Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
Since agricultural civilization developed ~20,000 years ago, land use/cover change (LUC) such as agricultural expansion spread throughout the world. More than 40% of global land are croplands and pasture now. LUC can impact climate at local, regional and global scales through biogeochemical and biogeophysical feedbacks. First, I present one case study for the biogeophysical impacts of afforestation in China on surface temperature because China has the largest afforested area in the world (∼62 million hectares in 2008). Afforestation is found to decrease daytime LST by about 1.1 ± 0.5 °C (mean ± 1 SD) and to increase nighttime LST by about 0.2 ± 0.5 °C, on average. The observed daytime cooling is a result of increased evapotranspiration. The nighttime warming is found to increase with latitude and decrease with average rainfall. Afforestation in dry regions therefore leads to net warming, as daytime cooling is offset by nighttime warming. Then, I will summarize the progresses about the feedbacks of LUC and vegetation greening on climate. Until now, most of studies reported the effects of LUC on temperature at local, regional and global scales, while few on precipitation. Land use including management is a key mitigation for climate change, but we still lack comprehensive recommendations for policymakers to realize potential climatic benefits.