Increased Dependency on Extreme Precipitation in a Warmer Climate

Abstract Growing evidence suggests that extreme precipitation increases over most regions globally as the climate warms. However, it remains poorly understood how the fraction of annual precipitation from extreme events changes due to warming‐induced alteration of both annual and extreme precipitation patterns. Understanding such changes is crucial for water resources and agricultural planning and management. Here, we propose the Extreme Precipitation Dependency Index (EPDI), a robust metric to quantify the relative contribution of extreme precipitation to annual totals under a warming climate. Using both climate model projections and observational data sets, we find that EPDI increases considerably beyond the UN's mitigation targets, with many global land regions experiencing a 15%–20% rise at 4°C warming. Hotspots include the African Sahel, Southeast Asia, Northern Australia, and the Amazon. Observations reveal that many regions are already experiencing increases in extreme precipitation contributions at rates exceeding model projections. We further explore the implications of these trends on rain‐fed agriculture, reservoir operations, and ecosystem health. Our analysis indicates that 54%–96% of global rain‐fed croplands may be adversely affected, alongside significant risks to boreal forests. These results reveal that low‐income countries, particularly those dependent on rain‐fed agriculture, are projected to receive a larger fraction of their annual precipitation from extreme events, likely resulting in reduced productivity and economic disruption. Overall, this underscores the urgent need to limit global warming to 1.5–2°C to mitigate widespread socio‐environmental consequences.