Modeling and predicting trends of heat stress in the outdoor environment using the CanESM2 model based on RCP scenarios: A case study in Yazd, Iran

Background: This study modeled changes in heat stress in outdoor environments over the coming decades, considering the effects of climate change and global warming. Methods: We used the Wet Bulb Globe Temperature (WBGT) and Humidex (HD) indices, based on the CanESM2 General Circulation Model (GCM) and the Statistical Downscaling Model (SDSM), to analyze data from the Yazd station, a location with a dry climate. Daily data on minimum and maximum temperatures and relative humidity were collected from the Yazd Meteorological Station for the base period of 1976–2005. Modeling was then performed for three 30-year periods: 2011–2040, 2041–2070, and 2071–2099, using three scenarios: RCP 2.6 (RCP 2.6), RCP 4.5 (RCP 4.5), and RCP 8.5 (RCP 8.5). Results: The results showed a clear increasing trend in both minimum and maximum temperatures across all periods and scenarios, with the most significant rise projected for 2071–2099. The WBGT and HD indices also followed an upward trend compared to the base period. Specifically, temperature increases were projected at 11.53%, 17.55%, and 29.04%, while WBGT and HD indices showed increases of 9.71%, 14.72%, and 24.84%, and 16.33%, 24.84%, and 41.95%, respectively. Conclusion: Overall, the modeling period from 2011 to 2099 indicated a consistent increase in temperature, humidity, WBGT, and HD across all months. This persistent trend highlights a growing challenge of heat stress due to climate change, underscoring the critical need for increased awareness and strategic planning for risk management in both communities and ecosystems.