Disentangling the Climatic Impacts of Anthropogenic Aerosols and Greenhouse Gases (Core Science Keynote)

Human activities contribute significantly to climate changes, but the magnitude of the radiative forcing relevant to anthropogenic aerosols and greenhouses (GHGs) remains highly uncertain. While both aerosols and GHGs are major byproducts from fossil fuel combustion, their implications for the Earth’s energy budget and the hydrological cycle are distinctive. In this talk I will discuss the competition of the GHG and anthropogenic aerosol forcing on the decadal trends of climate mean states as well as extreme events, such as Arctic sea ice melt, planetary wave activity, and winter extreme weather. The state-of-the-art climate models were employed in conjunction with long-term climate records to detect and characterize the anthropogenic aerosol footprints. Our results stress the importance of spatiotemporal variability of anthropogenic emissions in assessing the drivers of extreme weather in historical and future climate. Moreover, we investigated the relative impacts of air pollution and climate factors on crop yield based on statistical and machine learning model, and identified the co-benefit of the recent air pollution control policy from agriculture and food perspectives. However, our models predict that this benefit will eventually be diminished after the air pollution becomes alleviated in the full scale, while persisting or even exacerbated global warming will pose larger threat on the future food security.