Asymmetric global urban cooling potential demands accelerated and context-specific actions.

Rising urban temperatures and heat extremes pose an urgent global challenge, yet the potential for mitigating excessive urban heat-particularly at the global scale-remains unclear. Here, we quantify the cooling potential across 2,265 cities worldwide by the 2050s using validated urban climate simulations. Cooling effects are quantified as the reduction in the summer average wet-bulb globe temperature (WBGT) and heat danger hours (HDH; WBGT > 31.4 °C) under the combined implementation of reflective surfaces, green transformation, and anthropogenic heat reduction. We show a distinct spatial asymmetry: while the cooling potential increases with latitude, primarily due to greater cooling from reflective surfaces, the highest heat risk is concentrated in low- to mid-latitude regions (10°N-40°N). In these high-risk regions, combined mitigation is more effective at night, reducing HDH by an average of 37%, whereas daytime heat is mitigated to a lesser extent (11%). These asymmetries underscore the need for context-specific strategies-particularly accelerated action and localized innovation for low-latitude humid regions-as well as the integration of city-scale planning with targeted daytime heat risk interventions.