Baseline Temperature Variability Shaping Geographical Distribution of Future Hot Extremes under Anthropogenic Warming

Hot extreme events are among the most devastating disasters affecting human health and the natural environment. While there is broad consensus on an increasing severity of these events under anthropogenic warming, their geographical distribution exhibits substantial spatial heterogeneity, and its driving factors remain uncertain. Here, utilizing an eddy-resolving high-resolution climate model alongside multiple simulations from Coupled Model Intercomparison Project Phase 6, we find baseline temperature variability as a key factor shaping the global distribution of projected hot extremes, with over 80% of the global increase in hot extremes anticorrelated with baseline temperature variability. We further demonstrate that the baseline temperature variability is anchored by persistent land-atmosphere coupling, which endures over century timescales and sustains the spatial heterogeneity of future hot extremes. Our findings suggest that baseline temperature variability could serve as a potential indicator for future hot extreme distribution, offering valuable insights for developing targeted adaptation strategies and improving regional resilience.