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

Jie Chen,Tao Pan,Fubao Sun,Yanhua Liu,Yujie Liu,Quansheng Ge

doi:10.5194/esd-9-1097-2018

Abstract

Abstract. The Paris Agreement proposes a 1.5 ∘C target to limit the increase in global mean temperature (GMT). Studying the population exposure to droughts under this 1.5 ∘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 ∘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 ∘C global warming scenario relative to the reference period. Demographic change is the primary contributor to exposure (79.95 %) in the 1.5 ∘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 ∘C global warming scenario. The study suggested that reaching the 1.5 ∘C target is a potential way for mitigating the impact of climate change on both drought hazard and population exposure.

Highlights

The goal of the Paris Agreement is to pursue efforts to limit the increase in global mean temperature (GMT) to 1.5 ◦C above preindustrial levels, recognizing that this limit would significantly reduce the risks and impacts of climate change (UNFCCC, 2015)
According to the correspondence between representative concentration pathways (RCPs) and shared socioeconomic pathways (SSPs) provided by the IPCC, RCP2.6 generally corresponds to SSP1
Population data for SSP1 was obtained from the National Institute for Environmental Studies (NIES), Japan, which was downscaled from the International Institute for Applied Systems Analysis (IIASA) simulated results (Murakami and Yamagata, 2016)

Summary

Introduction

The goal of the Paris Agreement is to pursue efforts to limit the increase in global mean temperature (GMT) to 1.5 ◦C above preindustrial levels, recognizing that this limit would significantly reduce the risks and impacts of climate change (UNFCCC, 2015). Studies quantifying climate extreme events and their socioeconomic impacts under the 1.5 ◦C target are urgently needed. These types of studies are key content for the IPCC special report on the 1.5 ◦C target, which will be published in 2018. Risk is often represented as the probability of occurrence of hazardous events or trends multiplied by the impacts if these events or trends occur, it results from the interaction of hazard, exposure, and vulnerability (Field et al, 2014). As one of the most devastating natural disasters, droughts rank first in terms of globally affected populations (Mishra and Singh, 2010), and the frequency and intensity of droughts are likely to increase with global warming (Stocker et al, 2014; Field et al, 2012).

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Discussion

Conclusion