Comparing responses of summer extreme temperature to vegetation changes in China between satellite observations and numerical simulations

Human activities have a significant impact on the climate by altering vegetation types and modifying surface properties, resulting in more frequent and intense extreme weather events, which pose a threat to the sustainable development of the environment. However, the specific effects of vegetation change on extreme temperature events are not fully understood. To address this gap, we conducted evaluations with both in-situ observations and the regional climate model to determine the contributions of different vegetation transitions to extreme temperature changes over China. Our findings indicate that vegetation plays an important role in local heatwaves. Cropland have a stronger heating effect than grassland and forests in lifting the daily maximum temperature but present shorter hot day durations. Uncertainties are high in grassland than those of forest due to more diverse background climatic conditions of grassland sites. Numerical simulations revealed a decrease in extreme temperatures such as a 0.85℃ decrease in the daily maximum temperature and 2.65 fewer hot days, which can be attributed to changes of cloud radiation and sensible heat flux resulting from large-scale deforestation in the southern region and cropland expansion in central China. Converting forests to woody savannas led to a significant reduction in leaf area index and latent heat flux in the southern and northeastern regions. Changes in surface property have a stronger relationship with the average temperature changes than with extreme temperature changes. Overall, our study quantitatively evaluates the impact of different vegetation types and their property changes on regional extreme temperature changes, which have important implications for ecological protection and policy-making in China.