The Cooling Needs to Reduce Indoor Humid-Heat Risks for Global Low-Income Populations Should Be Incorporated into Global Carbon Emission Reduction Plans

In recent years, global summer heat waves have intensified markedly, and humid-heat stress is now a quantifiable threat to human health, particularly for low-income populations. Using validated, publicly available data, we computed the global distribution of populations with the highest indoor humid-heat risk and deprivation index and then employed the most widely adopted urban module of the Community Earth System Model (CESM) to estimate the electricity and carbon dioxide required to provide equitable air-conditioning cooling to these groups. Our results indicate that India exhibits the highest combined indoor humid-heat risk and deprivation index, while the top ten countries are dominated by low-income nations in Africa. If these regions were to receive equitable access to air-conditioning cooling, they would consume 1,652 terawatt-hours of electricity and generate an additional 607 million tons of carbon dioxide by 2050. Achievable mitigation pathways include improving building-envelope performance and enhancing the cooling coefficient of performance (COP) of air-conditioning systems, challenges that demand new building materials and next-generation air-conditioning technologies for energy efficiency. Given that some of our data are static, our results entail a degree of uncertainty; they are credible at the order-of-magnitude scale, and fully precise projections will be refined once dynamic data become available in the future.