Compound Hot-Dry Extremes Amplify Disproportionate Climate Risks for Low-Income Nations

Droughts and hot extremes, individually and in combination, are intensifying, driven by anthropogenic greenhouse gas emissions. However, a globally comparable and cross-national assessment of the future risks posed by these events remains a critical gap. Our analysis shows that under current policies, leading to ∼2.7°C warming by 2100, 28.5% ± 9.3% of the global population (roughly 2.6 ± 0.9 billion people) may face heightened compound hot-dry extremes. Based on present-day per capita emissions, the cumulative lifetime emissions of ∼3.4 average global citizens (or ∼1.2 average US citizens) could expose one individual to these conditions by the end of century. Tropical island nations are expected to experience the most severe increases in compound hot-dry extremes. More critically, low-income countries, despite contributing minimally to global emissions, are projected to suffer more frequently than high-income countries. These findings underscore the urgent need for equity-focused, immediate policy action to address the socio-economic disparities exacerbated by climate change.