Projection of future hot weather events and potential population exposure to this in South Korea

Abstract

Heat waves, often caused by consecutive severe hot weather events, are responsible for the majority of medical costs associated with climate change in South Korea. In this study, we obtained a regional climate change scenario (RCP4.5) for South Korea, with 7.5 x 7.5 km horizontal resolution and extending up to 2100, by dynamically downscaling from results of the Community Earth System Model (CESM) with the Weather Research and Forecasting (WRF) model. We analyzed hot weather events (daily maximum temperature > 33 degrees C) in summer (June-August), focusing on changes in extent and frequency. According to our analysis, the area exposed to hot weather events in August will expand to cover similar to 70% of the nation in the middle of this century, with a rate of increase of 0.24% yr(-1). We calculated the population exposed to hot weather events in Korea, considering both spatial coverage and number of event days. Population exposure was projected to increase almost 3-fold, from 26% of the national population during the 2010s to 72% during the 2090s. In particular, exposure of the elderly population (> 65 yr old), who are particularly vulnerable, was expected to rapidly increase, with similar to 22% of the national population (similar to 10.4 million people aged > 65 yr) affected in the middle of this century when we considered the future projection of rapid aging of the South Korean population structure. Our projection of extensive hot weather events starting from the middle of the 21st century suggests the need for urgent government long-term measures and enforcement to ensure an early response to extreme weather events in Korea.