Baseline temperature variability shapes the geographical distribution of future hot extremes under anthropogenic warming

The intensifying hot extreme events under anthropogenic warming severely affect human health and the natural environment, yet the factors driving their heterogeneous geographical distribution remain unclear. Here we utilize 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, a relationship interpretable within the signal-to-noise ratio framework. 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. Over 80% of the global increase in hot extremes is anticorrelated with baseline temperature variability, according to analyses of multi-model climate simulations.