Asymmetric impacts of tropical forest gain and loss on temperature due to forest growth revealed by satellite observation

Forest gain in the tropics is always assumed to cool land surface as much as the warming induced by forest loss. However, the observations from multiple satellites show that the impacts of forest gain on local land surface temperature are robustly weaker than forest loss. This asymmetry comes from the contrasting changes of vegetation properties, which are verified by vegetation indices. Forest loss which is primarily caused by intense disturbances such as fire and deforestation, could result in the rapid change of biophysical processes, while forest gain is mainly related to vegetation regrowth, whose changes are not often that rapid. These asymmetric effects of forest gain and loss are not well represented in current Earth system models because of the fixed biophysical parameters used, thus could lead to the overestimation of the climatic mitigation of forestation in the future, especially in a short period. This highlights the necessity to improve the representation of forest demographic on biophysical vegetation properties for better projecting the climate benefits of future forestation.