Aerosol‐planetary boundary layer (PBL) interactions have been found to enhance air pollution in megacities in China. We show that black carbon (BC) aerosols play the key role in modifying the PBL meteorology and hence enhancing the haze pollution. With model simulations and data analysis from various field observations in December 2013, we demonstrate that BC induces heating in the PBL, particularly in the upper PBL, and the resulting decreased surface heat flux substantially depresses the development of PBL and consequently enhances the occurrences of extreme haze pollution episodes. We define this process as the “dome effect” of BC and suggest an urgent need for reducing BC emissions as an efficient way to mitigate the extreme haze pollution in megacities of China.

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The Tibetan Plateau (TP) is known as one of the sentinels of global climate change. Substantial winter warming over the TP will likely lead, directly or indirectly, to a series of geological disasters such as snow and glacial avalanches. Hence, for better adaptation to climate change, it is vital to project the future change in winter temperature over the TP. However, the current state-of-the-art climate models involved in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) still produce strong cold biases over most parts of the TP in their historical simulations. On the basis of selecting the optimal models, here we use the statistical downscaling method to constrain the projected winter temperature in CMIP6 models. The results show that the regions with the strongest winter warming over the TP will be near the Himalayas and the densely populated eastern regions. The constrained warming magnitude is much greater than that in the ensemble mean of the original 32 CMIP6 models or six best models over these regions. Therefore, early warning and forecasting services should be strengthened for the future temperature over these regions. Moreover, the long-term spatial warming varies greatly under four different future emission scenarios. Under the most severe scenario, the increase in winter temperature near the Himalayas exceeds 10℃, which will greatly destabilize glaciers in the region, while the increase is only 4–6℃ under the weakest scenario. Therefore, it is urgent to reduce greenhouse gas emissions to control the future temperature increase at hotspots of climate vulnerability such as the TP.