The 2022-like compound dry and hot extreme in the Northern Hemisphere: Extremeness, attribution, and projection

Droughts, hot extremes, and their combinations (i.e., compound dry and hot extremes, CDHEs) may pose threats to ecosystems and human society under global warming. The year 2022 has undoubtedly been a challenging year fueled by severe droughts, scorching hot days, and their concurrences in the Northern Hemisphere (NH), promoting the escalation of natural disasters. Though the analysis of individual droughts and hot extremes has been witnessed, the systematic assessment of CDHEs during summer 2022 remains largely underexplored. In this study, we used monthly precipitation and temperature data from the ERA5 covering the period of 1950–2022 to explore the extremeness of summer CDHEs across the NH. In addition, we explored the anthropogenic influences on the 2022-like CDHEs area and projected the likelihoods based on simulations from the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6) models. Results show that the spatial extent of CDHEs during summer 2022 across the NH reached the second highest in historical periods. Regional assessments show that the spatial extent of CDHEs in Europe was the largest since records began in 1950. Event attribution analysis demonstrates that the 2022-like CDHEs area during summer in the NH would have been virtually impossible without anthropogenic climate change. Future projection under different warming levels (1.5 °C, 2 °C, and 4 °C, respectively) indicates an increased probability of the 2022-like CDHEs area under SSP585. This study provides useful insights for understanding the extremeness, anthropogenic influence, and future likelihoods of CDHEs during summer 2022 in the NH.