Exploring Future Spatio-Temporal Drought Characteristics in France under Different Warming Levels

Droughts have severely impacted France across multiple socio-economic sectors (agriculture, energy, forestry), with climate change projected to aggravate these events. To construct tangible assessments of future drought risks, we develop a comprehensive framework analyzing meteorological, soil moisture, and hydrological droughts across short-term and long-term timescales using standardized drought indices. Our analysis benefits from a recent ensemble of high-resolution hydro-climate simulations (1960-2100) and treats droughts as contiguous spatiotemporal events. To quantify the projected changes, three historical drought events serve as references: 1976, 1989, 2015. We analyze drought evolution by focusing on three spatio-temporal characteristics: duration, spatial extent and intensity. We examine whether these characteristics exhibit significant trends for the RCP8.5 scenario, how their distributions for different global warming levels (+1.5°C, +2°C, +3°C) evolve, and detail the drought evolution in two contrasted hydro-climate simulations (storylines). All drought types present a significant intensity increase under climate change, with current benchmark intensities becoming more frequent even under +1.5°C warming. At +3°C warming, 8-17% of soil moisture and hydrological drought events exceed the exceptional duration of the 1989 event. Notably, even the wettest storyline does not significantly reduce drought intensity, duration, and spatial extent, while the driest one generates unprecedented drought conditions. As a result, adaptation planning should take into account the increased frequency of historical benchmarks, but also drought conditions exceeding them. Our analysis also highlights the sensitivity of future drought projections to how well models represent key driving factors: evolving aerosol concentrations and vegetation physiological responses to increasing CO₂.