Detection and attribution of the decreasing precipitation and extreme drought 2020 in southeastern China

Abstract

• Precipitation deficit 2020 over southeastern China results from anomalously persistent WPSH and weak cold air intrusion. • Anthropogenic aerosol effects have decreased precipitation and increased drought occurrences. • Anthropogenic impacts on the intensity, duration, and severity of drought are not detectable. Southeastern China experienced a drying trend and the precipitation deficit in 2020 exerts great stress to the water supply and the environment. This paper analyzed the large-scale climate patterns relating to the precipitation deficit in 2020 and attribute the decreasing precipitation and drought over southeastern China based on observations and large GCM ensembles, including HadGEM3-GA6 and CESM LENS single forcing simulations. Results show that the precipitation deficit in 2020 mostly results from the anomalously persistent WPSH over South China and a lack of cold air intrusion to South China, and it is also associated with the La Niña-like Pacific. Detection analyses show that anthropogenic influences have resulted in decreasing precipitation. The aerosol emissions, including industrial aerosols (AER) and biomass burning aerosols (BMB), have substantially decreased precipitation over southeastern China, while the greenhouse gas emissions (GHG) have slightly increased precipitation. Because the AER and BMB effects of decreasing precipitation are larger than the GHG effects of increasing precipitation, precipitation shows a decreasing trend in recent decades. However, as the aerosols emission from industry and biomass burning decreases, the AER and BMB effects of decreasing precipitation will be reduced. Future precipitation over southeastern China is projected to increase due to the GHG effects of increasing precipitation. There were AER and BMB impacts on occurrences of drought over southeastern China, but the anthropogenic GHG impacts on the intensity, duration, and severity of drought are not detectable.