Geographical Sciences PhD Student Aolin Jia, Professor Shunlin Liang and Associate Professor Dongdong Wang, and scientists from Beijing Normal University (Professor Bo Jiang and Xiaotong Zhang) recently published a new paper, titled "Air pollution slows down surface warming over the Tibetan Plateau" in the Atmospheric Chemistry and Physics, revealing that air pollution dominates the solar dimming over the Tibetan Plateau and has a depressing effect on local climate warming. 

The Tibetan Plateau (TP) plays a vital role in regional and global climate change. The TP has been undergoing significant surface warming since 1850, with an air temperature increase of 1.39 K and surface solar dimming resulting from decreased incident solar radiation. The causes and impacts of solar dimming on surface warming are unclear. In this study, long-term (from 1850–2015) surface downward radiation datasets over the TP are developed by integrating 18 Coupled Model Intercomparison Project Phase 5 (CMIP5) models and satellite products. The validation results from two ground measurement networks show that the generated downward surface radiation datasets have a higher accuracy than the mean of multiple CMIP5 and the fused datasets of reanalysis and satellite products. After analyzing the generated radiation data with four air temperature datasets, we found that downward shortwave radiation (DSR) remained stable before 1950 and then declined rapidly at a rate of -0.53 W m-2 per decade and that the fastest decrease in DSR occurs in the southeastern TP. Evidence from site measurements, satellite observations, reanalysis, and model simulations suggested that the TP solar dimming was primarily driven by increased anthropogenic aerosols. The TP solar dimming is stronger in summer, at the same time that the increasing magnitude of the surface air temperature is the smallest. The cooling effect of solar dimming offsets surface warming on the TP by 0.80 ± 0.28 K (48.6 ± 17.3%) in summer since 1850. It helps us understand the role of anthropogenic aerosols in climate warming, and highlights the need for additional studies to be conducted to quantify the influence of air pollution on regional climate change over the TP.

 

figure for long-term surface radiation variation and temperature change over the Tibetan Plateau