2024 Mega-Heatwaves

The year 2024 witnessed unprecedented heatwaves across the globe, with extreme temperatures affecting South America, Africa, Europe, and many other regions. These intense heat events have become more frequent and severe due to human-induced climate change; therefore, it is critical to assess their current state and future projections. In this study, the global 2024 Mega-heatwave was analyzed. We used the ECMWF Reanalysis v5 (ERA5) data to calculate heatwave indices (number, frequency, and magnitude) and assessed the normality of the event. We further developed a novel heatwave normalized index (HWNI) that combines the three conventional indices. Additionally, we calculated HWNIs for future projections under four Shared Socioeconomic Pathway (SSP) scenarios (SSP126, SSP245, SSP370, and SSP585) using 14 Global Circulation Models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to analyze the expected frequency of global heatwaves as strong as the 2024 Mega-Heatwave over time. Our results confirmed that significant increases in the number of heatwaves and total heatwave days in 2024, and also found regional differences in the major characteristics of the 2024 Mega-heatwave across the globe. This study underscores the critical importance of continued monitoring and analysis of extreme heat events to inform climate policy and adaptation strategies in the face of rapidly changing global temperatures.This study is supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (2022R1C1C2009543, RS-2022-KE002030) and the Korea Environment Industry & Technology Institute (KEITI) funded by Korea Ministry of Environment (2022003640002).