Estimation of future global population exposure to heatwaves—based on the heat stress index

doi:10.12006/j.issn.1673-1719.2019.253

Abstract

Abstract:

Climate changes have contributed to increasing heatwaves all over the world. Wet bulb globe temperature, is a combined measure of temperature and humidity effects on the thermal condition. Thus it is a better indicator of the impact of heatwaves on humans than temperatures alone, and used to define heatwaves in this study. Utilizing simulated daily mean surface temperature and relative humidity from climate models participating in the Coupled Model Inter-comparison Project Phase 5 (CMIP5) and spatially explicit population projection from the Shared Socioeconomic Pathway (SSP), we estimate change in future population exposure to heat waves taking account of both climate and population factors. Results show that during the historical period (1986-2005), geographic variations in exposure are generally a function of population and tend to be the highest in the Indian subcontinent, east and southeast of China. During the 2081-2100 period, exposure remains high in these regions, however substantial portions of the globe are expected to have large increases, particularly across the tropical regions. Significant differences exist in exposure change among different regions. South Asia is projected to have the largest annual mean exposure increase of approaching 300 million person-days, but in North Australia, North Asia and Canada, the increase is less than 1 million person-days. For the vast majority of tropical regions, the combined effect contributes to total change in exposure most prominently. But the climate effect is the most important factor for the middle and high latitudes. At the global level, the combined effect is the most prominent contributor to overall change in exposure.

Key words: Heatwaves, Wet bulb globe temperature, Population exposure, Global, Projections

CHEN Xi, LI Ning, ZHANG Zheng-Tao, LIU Jia-Wei, WANG Fang. Estimation of future global population exposure to heatwaves—based on the heat stress index[J]. Climate Change Research, 2020, 16(4): 424-432.

Figures/Tables 6

Table 1 Overview of the 14 CMIP5 models used in this study

Fig. 1 Spatial distributions of climatology of annual mean WBGT, the threshold and the number of annual total heatwave days during the historical period (1986-2005) from ERA-Interim reanalysis and MME (multi-model ensemble) of CMIP5 historical runs

Fig. 2 Annual total days of heatwaves, population and population exposure during the historical period (1986-2005) and the future period (2081-2100), and their respective changes (Curves to the right of each panel represent their zonal averages)

Fig. 3 Geographical distributions of 26 regions used as well as the respective acronyms based on IPCC[33]

Fig. 4 Decomposition of regional mean projected change in exposure

Fig. 5 Decomposition of global mean projected change in exposure over the four future periods (Each error bar illustrates standard deviation in total projected exposure change across the models for each period/effect)

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