Regional changes in extreme heat events in China under stabilized 1.5 °C and 2.0 °C global warming

Abstract

Extreme heat events (EHEs) have a significant impact on the social economy and human health. China is a country with a large population and diverse terrain, and it is necessary to project future extreme heat changes in the sub-regions. This study used a specially designed dataset, the Community Earth System Model (CESM) simulations, namely CESM low-warming, to investigate the EHEs in China under 1.5 °C and 2.0 °C global warming. The results indicate that the regional mean warming over China will exceed the global average, about 1.63 °C and 2.24 °C in 1.5 °C and 2.0 °C warmer futures. Compared to the present-day (1976–2005), the frequency and duration of the EHEs in South China are projected to increase the most among the sub-regions. For example, the frequency of EHEs in South China at 1.5 °C and 2.0 °C warming will exceed 3 and 3.5 times the present-day level. However, when global warming rises from 1.5 °C to 2.0 °C, the increased impacts relative to the 1.5 °C warming level will be the lowest in South China (less than 40%), and the highest increased impacts are projected to appear in Northeast China (53%–84%) and Northwest China (53%–107%). The main reason for this situation is that compared with the 1.5 °C scenario, the upper zonal westerly in northern China weakens and the continental high pressure enhances under the 2.0 °C scenario. Therefore, limiting global warming at 1.5 °C instead of 2.0 °C is beneficial for eliminating extreme heat events, especially for Northeast China and Northwest China.