Modeling the effects of realistic land cover changes on land surface temperatures over China

In recent decades, China has experienced intense land use and cover change (LUCC). In this study, we modeled and explored the possible effects and mechanisms of realistic LUCCs on surface temperatures in China during 1984–2013 using the Regional Climate Model (RegCM) based on the annual dynamic LUCCs derived from Global Land Surface Satellite (GLASS-GLC) data. We compared two sets of ensemble experiments, one with a fixed LUCC scenario (fixed at 1984) and the other with a dynamic LUCC scenario (annual conversions from 1984 to 2013). The results showed that LUCCs in recent decades have been characterized by reforestation (accompanied by a reduction in cropland) in southern China, grassland-to-cropland conversions in North and Northeast China and bare land-to-grassland conversions in northwestern China. Such LUCCs led primarily to significant cooling of the daily maximum surface temperature ( T smax ) by approximately − 0.3 to − 0.6 °C in summer and autumn over the reforestation areas of southern China, followed by moderate cooling (~ − 0.2 °C) of the daily mean surface temperature ( T s ), while the effect on the daily minimum surface temperature ( T smin ) was weak (within ± 0.1 °C) and nonsignificant. During winter and spring, the impacts of LUCC on all temperatures were less pronounced. Further investigation revealed that the cooling of T smax was dominated by the direct effects of LUCC (over 90%), particularly the reduction in aerodynamic resistance associated with the cropland-to-forest conversions in southern China. Additionally, seasonal differences and uncertainties in the LUCC-induced cooling of T smax were likely due to a combination of the relatively stable direct effect of LUCC and the uncertain model internal variability. Overall, our study highlights the effects of realistic and transient LUCC scenarios, which could provide insightful scientific clues to better assess and understand climate change.