Population exposure to compound dry and hot events in China under 1.5 and 2°C global warming

Abstract

Both droughts and hot extremes may exert critical impacts on human society, and their concurrence is no exception. Global warming is expected to increase the frequency and intensity of compound dry and hot events widely, the impacts of which will be particularly severe for sensitive and vulnerable sectors. However, projected risk and impact of compound dry and hot events in China are less assessed, especially in the context of the goals specified by the Paris Agreement in 2015. Here, we show an overall increased risk of compound dry and hot events on human health in China, particularly in eastern regions, for the two warming levels (1.5 and 2°C) based on Coupled Model Intercomparison Project Phase 5 climate models. The population exposure to extreme compound dry and hot events is projected to increase by about 165.46% for the 1.5°C warming and about 200.49% for the 2°C warming compared with the exposure in the present period 1986–2005. These potential variations are driven by climate change and population change with climate effect being the dominantly positive contributor. These findings highlight the urgent need for more efforts to limit warming within 1.5°C to reduce the risk of compound dry and hot events and associated impacts on human society.

Population Exposure to Compound Droughts and Heatwaves in the Observations and ERA5 Reanalysis Data in the Gan River Basin, China

“…The contributions of the climate change effect to CDHW exposures were much greater than those of population and joint change effects. This was different from the results of exposure characteristics related to extreme climate events reported in previous studies [41,42,44], because the previous studies were based on future climate and population outputs by the models. Under the characteristics of different CDHW grades, the contribution rates of climate change effect were basically the main cause for the change in the CDHW exposures.…”

“…CDHWs can amplify the damage of the individual droughts and heatwaves, ultimately wreaking a catastrophic effect on the environment, society, economy, and human health [44,54]. The summer CDHWs in Europe in 2003 and China in 2013 caused a high increase in mortality, especially in the elderly and infant populations as well as in persons the anticyclone anomaly center near the GRB suppressed precipitation due to the relatively large positive values of water vapor flux divergence anomalies, which likely made the basin prone to droughts.…”

“…CDHWs can amplify the damage of the individual droughts and heatwaves, ultimately wreaking a catastrophic effect on the environment, society, economy, and human health [44,54]. The summer CDHWs in Europe in 2003 and China in 2013 caused a high increase in mortality, especially in the elderly and infant populations as well as in persons with pre-existing cardiovascular and respiratory conditions [9,11,34,36,55].…”

“…The damage was particularly severe in both eastern and southern China, which are densely populated areas [11,39]. Scenario population data (e.g., shared socioeconomic pathways) have been examined to explore the characteristics of population exposure to climate extremes [40], such as extreme precipitation [41], heatwaves [36,42], and droughts [43,44]. Yet, research on the exposure of the population to hydroclimatic extremes using long-term population observation data is still relatively rare, especially for CDHWs.…”

Changes in compound hot and dry day and population exposure across China under climate change

“…The 2003 European and 2010 Russian heatwaves accompanied by severe droughts have caused high mortality rates (Robine et al ., 2008; Miralles et al ., 2014; Russo et al ., 2015). Both hot and dry extremes pose adverse threats, the concurrence of the two extremes is no exception and ignoring their concurrence may underestimate the impact on human society (Zscheischler et al ., 2018; Feng et al ., 2019; Wu et al ., 2021). Population exposure has been widely used to evaluate the impact of climate extremes on human society (Huang et al ., 2018; Chen et al ., 2018b).…”