Delineating the predominant impact of rising temperature on the enhancement of severity in compound drought-hot events in China: An empirical Copula and path analysis-based approach

Abstract

Study regionChina Study focusCompound drought-hot events (CDH) inflict serious socio-economic damages on our society and the natural environment. Given the inverse relationship between average summer temperature and precipitation, this investigation introduces an innovative empirical copula-based compound drought-hot index (CDHI). This index is crafted from the joint distribution of the standardized precipitation evapotranspiration index (SPEI) and standardized temperature index (STI). While previous research has documented a rising trend in these complex events on both regional and global stages, scrutiny into their escalating severity remains limited. To highlight the critical role of climbing temperatures in the increasing severity of CDH events within China, our research utilizes the CDHI in tandem with a path analysis to precisely assess severity shifts in CDH occurrences during the warm season from 1901 to 2022. New hydrological insights for the regionThis study used an empirical copula-based CDH index and implemented the path analysis to quantify the response of severity changes of compound drought-hot events to shifts of summer mean temperature and water deficit from the historical perspective. Our findings reveal a marked escalation in CDH severity across much of China. Path analysis divulges that the influence of rising summer temperatures on CDH severity has seen a significant uptick in the last 60 years (1962–2022), displaying a more considerable contribution rate than the earlier 60-year span (1901–1961). This points to the changing impact of temperature on CDH events over recent decades. During the initial interval (1901–1961), we saw a 0.7% and 1.7% per-decade increase in areas affected by severe and moderate CDH events, respectively. Contrastingly, the subsequent period (1962–2022) experienced a more significant rise, with the area affected by severe and moderate events expanding over twice as much. Totally speaking, this exploration enhances our comprehension of the intensification in CDH event severity and the role of climatic drivers. These insights can contribute to improved risk assessments and the development of tailored adaptation and mitigation strategies in the face of ongoing climate change.