资源环境科技发展态势分析平台

Based on the simulated temperature and precipitation from CMIP6 models, the joint distribution characteristics of summer temperature and precipitation in China are described in the Copula approach; the occurrence risk of compound extremes (i.e., warm/dry, and warm/wet events) and corresponding univariate events (i.e., warm, wet, and dry events) in historical period are compared; and the risk changes of compound extremes are discussed under global warming 1.5 °C and 2 °C. Results show that: 1) the Copula approach can describe the joint probability distribution of summer temperature and precipitation in observation and model simulations in most parts of China except for the Qinghai-Tibet Plateau; 2) The average risk of warm and wet events in China increases by 2.3 and 1.16 times under 1.5 °C warming respectively, increases by 2.83 and 1.29 times under 2 °C warming respectively while the risk of dry events decreases in most parts of China; 3) The average of warm/wet events in China increases by 5.48 and 10.01 times under 1.5 °C and 2 °C warming, respectively. Regions over Northern China and South China experience the most increased risk about more than 8 times. The warm/dry events show less increase magnitude with 1.82 and 2.04 times under two warming climates, respectively. The highest increase in risk is mainly located in Northern China. At an additional 0.5 °C warming from 1.5 °C to 2 °C, the regional average risk of warm/dry and warm/wet events increases by 1.40 and 2.74 times, respectively. In most areas, the risk of warm/wet events increases significantly and are greater than that of warm/dry events. This indicates that controlling global warming up to 1.5 °C can avoid more intense warm/dry and warm/wet events. Our work highlights that the risk of compound extremes may be underestimated if we only consider the univariate events.