Abstract
Global drought variability of past centuries remains poorly understood due to sparse instrumental records and limited paleoclimate reconstructions. Yet, quantifying long‐term forced and unforced variability is key for assessing the extremeness of modern (2000–2024) drought events. Here, we combine 20 ensemble members from a 600‐year climate simulation (ModE‐Sim, 1420–2009) and modern reanalysis data (ERA5Land, 1950–2024) to place recent droughts in a multi‐century context. Drought magnitude and timing are measured using the annual maximum potential cumulative water deficit (PCWD), which integrates atmospheric moisture demand and supply, the daily timing of precipitation events, snow melt, and radiation. We analyze the deviation of modern annual, multi‐year mean, and 30‐year extreme PCWD from alternative reference periods that sample forced and unforced variability to a variable extent. We find a strong decline in the number of regions with unprecedented modern (2000–2024) single‐year and 25‐year mean PCWD as the reference is extended into the past and with the additional consideration of unforced atmospheric variability. This is not the case for extreme droughts. 30‐year extreme PCWD has increased beyond the range of variability of the last 600 years in over half of all regions globally. This suggests that drought extremes are intensifying more rapidly beyond the range experienced in the past than mean conditions. While individual droughts in the modern era may not appear unprecedented when viewed against a century‐long record, the shift in their frequency distribution indicates a rising risk of damaging impacts and an increasing likelihood of droughts reaching unprecedented magnitudes in the near future.
