Closing the Cooling Gap Could Halve Global Heat-related Health and Economic Losses

The escalating threat of global warming has intensified pervasive concerns over its profound health impacts. Even under ambitious climate mitigation pathways, a substantial ‘cooling gap’ persists, leaving billions of people without access to thermal protection due to socioeconomic constraints. This deficit exacerbates heat-related mortality, undermines labor productivity, and erodes global economic output. Therefore, closing this cooling gap through robust adaptation policies is of paramount importance. Air conditioning (AC) represents one of the most mature and effective interventions for health adaptation. However, the projected scale of future demand and the global health and economic benefits accruing from varying AC adaptation policies remain insufficiently quantified. This knowledge gap obstructs the optimized allocation of climate funds and the design of actionable adaptation polices.

To address this, we introduce a novel framework that quantifies global AC demand and its associated health-economic benefits under various mitigation and adaptation scenarios. We begin by employing a process-based approach to project future cooling demand across 170 countries under 3 SSP-RCPs. We further develop a method to assess how different AC access patterns—defined by operational thresholds and access rates—mitigate global heat-related mortality and labor productivity losses. Second, we construct a series of statistical emulators that efficiently characterize the response relationships between temperature increase, AC access patterns, cooling demand, and health outcomes. These emulators allow us to circumvent the limitations of fixed scenarios, and we use them to evaluate impacts under 27 combined mitigation and adaptation policy scenarios. The mitigation scenarios comprise current NDCs and the 1.5°C and 2°C targets, while adaptation scenarios are centered on Decent Living Standards (DLS), incorporating three AC operational thresholds (no_DLS, lax_DLS, strict_DLS) and three access rates (self_adaptation, 2050_DLS, and 2030_DLS). Finally, these health impacts are integrated into a global CGE model (C3IAM/GEEPA) to assess the consequent effects on the global macroeconomy and inequality.

Our findings indicate that while the global cooling gap will contract as socioeconomic development outpaces warming, developing regions in low-to-mid latitudes will continue to face a "cooling dilemma" characterized by high demand and low adaptive capacity. We find that compared to NDCs, more ambitious mitigation like the Paris Agreement (1.5°C and 2°C) yields relatively modest reductions in health-economic losses (0.03–0.07% of the GDP). In contrast, ensuring universal access to decent cooling by 2050 could halve global GDP losses. Accelerating this goal to 2030 would provide an additional cumulative economic gain of approximately 200 trillion USD. Closing the cooling gap offers robust protection for developing regions—particularly India, Asia, the Middle East and Africa- but it remains insufficient to bridge the deep-seated disparity in losses between developing and developed economies. Operational thresholds significantly dictate both cooling demand and realized benefits, necessitating a strategic trade-off between intervention efficacy and population coverage to ensure global climate equity.