Journal of Geographical Sciences ›› 2018, Vol. 28 ›› Issue (10): 1371-1384.

• Orginal Article •

### Projected changes in population exposure to extreme heat in China under a RCP8.5 scenario

Dapeng HUANG1,2(), Lei ZHANG3, Ge GAO1,2, Shao SUN1

1. 1. National Climate Center, China Meteorological Administration, Beijing 100081, China
2. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China ;
3. National Meteorological Center, China Meteorological Administration, Beijing 100081, China
• Received:2018-01-09 Accepted:2018-02-28 Online:2018-10-25 Published:2019-01-04
• About author:

Author: Huang Dapeng (1978-), PhD and Associate Professor, specialized in natural hazard risk assessment, climate change impact assessment and application of remote sensing & GIS. E-mail: dapenghuang@163.com

• Supported by:
National Natural Science Foundation of China, No.41101517;National Industry-specific Topics, No.GYHY201506051;National Natural Science Foundation of China, No.41701103

Abstract:

Overall population exposure is measured by multiplying the annual average number of extremely hot days by the number of people exposed to the resultant heat. Extreme heat is also subdivided into high temperature (HT) and extremely high temperature (EHT) in cases where daily maximum temperature exceeds 35℃ and 40℃, respectively. Chinese population exposure to HT and EHT over four periods in the future (i.e., 2021-2040, 2041-2060, 2060-2081 and 2081-2100) were projected at the grid cell level in this study using daily maximum temperature based on an ensemble mean of 21 global climate models under the RCP8.5 scenario and with a population projection based on the A2r socio-economic scenario. The relative importance of population and climate as drivers of population exposure was evaluated at different spatial scales including national and meteorological geographical divisions. Results show that, compared with population exposure seen during 1981-2010, the base period, exposure to HT in China is likely to increase by 1.3, 2.0, 3.6, and 5.9 times, respectively, over the four periods, while concomitant exposure to EHT is likely to increase by 2.0, 8.3, 24.2, and 82.7 times, respectively. Data show that population exposure to HT is likely to increase significantly in Jianghuai region, Southwest China and Jianghan region, in particular in North China, Huanghuai region, South China and Jiangnan region. Population exposure to EHT is also likely to increase significantly in Southwest China and Jianghan region, especially in North China, Huanghuai, Jiangnan, and Jianghuai regions. Results reveal that climate is the most important factor driving the level of population exposure in Huanghuai, Jianghuai, Jianghan, and Jiangnan regions, as well as in South and Southwest China, followed by the interactive effect between population and climate. Data show that the climatic factor is also most significant at the national level, followed by the interactive effect between population and climate. The rate of contribution of climate to national-level projected changes in exposure is likely to decrease gradually from ca. 70% to ca. 60%, while the rate of contribution of concurrent changes in both population and climate is likely to increase gradually from ca. 20% to ca. 40% over the four future periods in this analysis.