Population exposure to droughts in China under the 1.5°C global warming target

The Paris Agreement proposes a 1.5 degrees C target to limit the increase in global mean temperature (GMT). Studying the population exposure to droughts under this 1.5 degrees C target will be helpful in guiding new policies that mitigate and adapt to disaster risks under climate change. Based on simulations from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), the Standardized Precipitation Evapotranspiration Index (SPEI) was used to calculate drought frequencies in the reference period (1986-2005) and 1.5 degrees C global warming scenario (2020-2039 in RCP2.6). Then population exposure was evaluated by combining drought frequency with simulated population data from shared socioeconomic pathways (SSPs). In addition, the relative importance of climate and demographic change and the cumulative probability of exposure change were analyzed. Results revealed that population exposure to droughts in the east of China is higher than that in the west; exposure in the middle and lower reaches of the Yangtze River region is the highest, and it is lowest in the Qinghai-Tibet region. An additional 12.89 million people will be exposed to droughts under the 1.5 degrees C global warming scenario relative to the reference period. Demographic change is the primary contributor to exposure (79.95 %) in the 1.5 degrees C global warming scenario, more than climate change (29.93 %) or the interaction effect (-9.88 %). Of the three drought intensities - mild, moderate, and extreme - moderate droughts contribute the most to exposure (63.59 %). Probabilities of increasing or decreasing total drought frequency are roughly equal (49.86 % and 49.66 %, respectively), while the frequency of extreme drought is likely to decrease (71.83 % probability) in the 1.5 degrees C global warming scenario. The study suggested that reaching the 1.5 degrees C target is a potential way for mitigating the impact of climate change on both drought hazard and population exposure.