Global disparities in compound hazard exposure and infrastructure access jeopardize health equity

Rising natural hazards amid a warming climate increasingly threaten human health and sustainable development. While infrastructure serves as a critical buffer against these risks, the relationships between hazard exposure, infrastructure access, and health outcomes remain unclear. Here, we assess global human exposure to joint flooding and extreme heat risks since 2000 and examine their interactions with infrastructure access in shaping human health. Results reveal stark inequalities, with 48% of the global population (~ 4 billion people) living in areas highly exposed to both hazards. Low-income countries are disproportionately affected, facing 5.37 times the flood exposure and 1.98 times the extreme heat exposure of other income groups, yet having only 30% of their critical infrastructure access. Enhanced infrastructure access is significantly associated with longer life expectancy (p < 0.05), but high levels of hazard exposure diminish these benefits. Future projections under the Shared Socioeconomic Pathway (SSP) 1-2.6, 2-4.5, and 5-8.5 scenarios indicate substantial increases in country-level hazard exposure by 2100 relative to baseline levels: 40%–393% for floods and 22%–161% for extreme heat. The share of areas simultaneously exposed to high levels of both hazards rises from 15%–18% in 2030 to 22%–51% by 2100, potentially widening existing gaps in infrastructure access and health disparities. These findings highlight the urgent need for targeted interventions that enhance infrastructure equity in climate adaptation and health strategies, especially for vulnerable populations.