Future changes in heat stress over CORDEX East Asia phase 2 domain by the end of the century

Changes in summer heat extremes have been recorded all over the globe in recent years. East Asia is one of the most vulnerable areas for climate change, owing to a combination of natural and anthropogenic factors. The human experience of heat, however, does not only depend on the temperature itself but rather the combination of factors that regulate the exchange of heat with the environment. The present study uses Net Effective Temperature (NET), an index that combines the effects of temperature, humidity, and wind, to assess heat stress perception and its potential changes by the end of the century over East Asia. The data used in the study are maximums calculated from the three-hourly output of the 10 Coupled General Circulation Model (CGCM) - Regional Climate Model (CGM) chains participating in the Coordinated Regional Climate Downscaling Experiment (CORDEX)-East Asia phase 2. As human beings can acclimate to their environment, not only maximum values but also 95th percentiles of maximum values have been used. The assessment of the models showed that all of the models reproduced the current climate reasonably. The present study utilized two different scenarios, RCP8-5, and SSP5-8.5. In both scenarios, the increase in averages and 95th percentiles of both maximum temperatures and NETs over the whole domain has been projected. The increase in NET was projected to be higher than the increase in temperature itself, and the increase in the SSP5-8.5 scenario was projected to be higher than the increase in the RCP8.5 scenario, but the details of the warming patterns were dependent on the choice of model. Additionally, the Korean Peninsula and Japan have been shown to have the largest difference in the increase between heat stress and temperature, while the highest overall increase of both temperature and NET was projected over the North-Western part of the domain in both scenarios.