In East Asia, the growing threat of extreme heat is becoming a major hazard to both lives and livelihoods. The record-breaking temperatures seen in recent years, which climate change has contributed to, have intensified these challenges.

The urban heat island (UHI) effect further exacerbates these temperatures. Like climate change, the UHI effect is primarily a result of human activities. It stems from the scarcity of green spaces and the prevalence of heat-retaining surfaces such as concrete and asphalt in urban areas. It is especially concerning for tropical East Asian cities, where high humidity compounds the risk of overheating. These cities, already burdened by hot, humid conditions, are seeing further heat intensification due to climate change. For instance, in Phnom Penh, Cambodia, the UHI effect contributes to 23 to 25 heat wave days annually—a number expected to more than double by 2050 in some of the city’s districts.

The GFDRR report Unlivable: What the Urban Heat Island Effect Means for East Asia’s Cities explores three key issues: the intensity of the UHI effect in the region’s cities; how extreme urban heat affects the economic competitiveness, livability, and inclusiveness of these cities; and how city leaders can address these rising temperatures.

To grasp the full impact of extreme heat on public health, urban competitiveness, and livability, the report reviews the expanding body of scientific literature on heat stress. The results highlight the urgency of the issue. Every year, over 100,000 people in East Asia die due to extreme heat. Projections show that heat-related mortality will continue to rise as the effects of climate change worsen.

The UHI effect also has a negative impact on productivity. Studies indicate that the combination of UHI and global warming will result in a 1.4 to 1.7 percent decline in real gross domestic product for the median city by 2050. In the hardest-hit city, this loss could reach nearly 11 percent by the end of the century. New data in the report reveal that large metropolitan areas in Southeast Asia and East Asian cities with warmer climates suffer significant economic slowdowns during extreme heat events.

Extreme urban heat has also been shown to diminish the quality of life in affected areas. It reduces the livability of cities both directly, through unbearable temperatures and high humidity, and indirectly, by exacerbating social problems such as increased crime, violence, and traffic accidents.

The report, however, provides recommendations for tackling the issue. It introduces the Places, People, Institutions framework to mitigate extreme urban heat. First, cooling urban spaces— streets, parks, homes, and workplaces—can alleviate heat stress, improving both public health and economic performance. Second, certain groups—such as the elderly, children, outdoor workers, and those with pre-existing health conditions—are more vulnerable to heat waves. Providing timely information, health care, and heat wave shelters is crucial to saving lives. Lastly, addressing extreme heat requires coordinated action between city governments and local stakeholders.

This framework identifies six key strategies to help local leaders implement an agenda for heat resilience: promoting urban greening through strategic planning; cooling city spaces by incorporating informed wind, shade, and urban design; engaging building owners to address indoor heat; saving lives with early heat wave warnings; protecting workers exposed to heat; and integrating heat risk reduction into city institutions and strategies. By adapting these approaches to local contexts, East Asian leaders can enhance urban livability, ensuring that cities remain healthy, competitive, and inclusive spaces for all.

Since its launch in November 2023 at a high-level conference in Yokohama, Japan, the Unlivable study has informed fastgrowing policy dialogue and heat risk assessment work in several countries, including Cambodia, the Philippines, and Thailand. Among follow-up actions taken, GFDRR has provided financing and analytical support to assess heat risks and identify costeffective mitigation actions in Bangkok—one of Asia’s most heatexposed cities.