A stepwise-clustered concurrent extreme analysis for concurrent drought-heatwave events: a case study of North China

With changing climate conditions, the frequency of both heatwaves and drought increases significantly, leading to adverse social, economic, and environmental impacts. However, there have been few analyses of the future changes in concurrent drought-heatwave events (CONDHs) in North China. Therefore, a stepwise-clustered concurrent extreme analysis (SCEA) for concurrent drought-heatwave events is developed to investigate the spatiotemporal variations of CONDHs in North China under two common Shared Socioeconomic Pathways (i.e., SSPs) during the future period. Projected changes in four parameters (i.e., the annual frequency of occurrence, mean duration, total intensity, and maximum duration) of CONDHs for the future (i.e., 2031–2060 and 2061–2090) periods are analyzed based on the multi-model ensemble of 5 global climate models (GCMs). Evaluations of the multiple GCMs and their ensemble suggest that the developed approach is superior to any single GCM in capturing the characteristics of concurrent drought-heatwave events. The results indicate that most of North China shows a significant upward trend in the projected temperature (e.g., 0.46–0.70℃ per decade) and precipitation (e.g., -4.33 to 19.49 mm per decade) under the SSP5-8.5 scenario. The spatial changes and interannual trends suggest that North China will experience more CONDH events in the future, especially for 2061–2090 under SSP5-8.5. The four parameters from 2061 to 2090 are projected to increase by 1.83 events/year, 3.11 days/event, 15.80 days, and 16.06℃, respectively. Projections of future concurrent drought-heatwave events can provide valuable information for assessing extreme climate change and identifying desirable adaptation strategies.