Renewable Energy Droughts Under Global Warming

The replacement of fossil fuels with renewable energy is central to mitigating human-induced climate change and achieving climate neutrality. However, this transition depends on the reliability of renewable energy systems that are increasingly exposed to climate-driven variability. Climate change is expected to alter not only mean renewable energy potentials but also their extremes such as renewable energy droughts, defined as periods of simultaneous low wind and solar power generation. These events pose a growing challenge to energy security in highly decarbonized systems with limited flexibility and storage capacity. This study presents a global assessment of projected changes in renewable energy droughts under 1.5 °C, 2 °C, and 3 °C global warming scenarios using CMIP6 multi-model simulations. Wind and solar energy potentials are first estimated from wind speed and solar radiation using physics-based empirical approaches. These potentials are then combined into a Standardized Renewable Energy Index (SREI) constructed with copula functions to capture their joint dependence. Changes in renewable energy drought severity, duration, and frequency are subsequently evaluated across warming levels. The results reveal strong regional heterogeneity alongside an overall intensification of renewable energy drought characteristics with increasing warming. Based on a machine learning–based assessment of the drivers of changes in renewable energy droughts, solar radiation emerges as the dominant factor, with its influence strengthening at higher warming levels. By anticipating compound extremes in renewable energy supply and identifying hotspot regions, this work underscores the need to incorporate these intensifying events under global warming into energy system planning and risk-informed strategies, particularly in highly renewable power systems, to support a resilient low-carbon transition.