Exposure and capacity mismatch shapes multihazard adaptation priorities for older adults in the Yangtze Delta

Abstract Climate extremes threaten older adults unevenly because hazards, ageing and adaptive capacity are spatially mismatched. Here we develop EDGE, an equity-driven framework that quantifies multi-hazard exposure in aggregate and per-resident terms, diagnoses county-level healthcare-capacity mismatch, and derives the marginal benefit of added capacity analytically rather than by curve fitting. Applied to 201 counties in the Yangtze River Delta under four SSP pathways and five CMIP6 models, EDGE shows that elderly multi-hazard burden peaks in 2050–2075, when it rises 195% above baseline under SSP3-7.0. Counties with more advanced ageing hold systematically fewer hospital beds per older resident (Spearman ρ = −0.47), a persistent counter-need allocation. Marginal benefit is highest where high exposure intensity and low capacity coincide, concentrated in southern Anhui and northern Jiangsu: ensemble-mean returns in the priority group are 1.85 times those in the over-resourced group, and this ordering holds under every pathway and at any attenuation strength. Directing incremental healthcare investment there is a no-regret strategy.