Karachi is among nine major megacities in Asia and the Pacific expected to become “substantially hotter” in the coming decades, according to a new report released on Wednesday by the UN Economic and Social Commission for Asia and the Pacific (UN-ESCAP).
The Asia-Pacific Disaster Report 2025: Rising Heat, Rising Risk highlights how rapidly growing urban centres are increasingly vulnerable to extreme heat due to the urban heat island (UHI) effect. The report warns that temperatures in densely built cities could rise an additional 2°C to 7°C beyond global warming levels.
Urban Heat Threat Intensifying Across Mega Cities
The report notes that concrete surfaces, high-rise clusters and congested neighbourhoods trap heat, pushing temperatures significantly higher than surrounding rural areas. Rapid and unplanned urbanisation, shrinking green spaces and limited ventilation are worsening the problem.
UN-ESCAP states that the rising temperatures will place intense pressure on water supply, healthcare systems, and cooling infrastructure. Vulnerable groups — including children, the elderly and outdoor workers — will face the greatest risk.
The report identifies nine cities as particularly high-risk: Seoul, Tokyo, Beijing, Delhi, Karachi, Dhaka, Manila, Jakarta and Phnom Penh.
It further warns that heat stress in the Asia-Pacific region will escalate sharply under all future climate scenarios, with mortality potentially doubling by 2050.
The urban poor are expected to suffer the most, as they often live in overcrowded areas with minimal greenery and limited access to cooling or healthcare.
Rising Heat Linked to Droughts, Glacier Melt and Multi-Hazard Disasters
The report projects that between 2041 and 2060, countries such as Pakistan, Mongolia, Uzbekistan, Iran and Turkmenistan will experience the greatest increases in aridity due to high evaporation rates and declining surface water.
UN-ESCAP also highlights glacier melt as one of the most alarming consequences of climate change. Globally, glaciers have lost 5% of their volume this century. High Mountain Asia — including northern Pakistan — faces severe glacial lake outburst flood (GLOF) risks, with 9.3 million people exposed to more than 2,200 glacial lakes.
By 2060, countries including Iran, Mongolia, Myanmar, Türkiye and Uzbekistan could lose over 70% of their glacier mass, creating extreme downstream flooding risks.
The report warns that, by 2100, regional disaster losses could soar from $418 billion to $498 billion under worst-case climate projections.
It stresses the urgent need for heat-focused planning, early warning systems, scientific innovation and regional cooperation. Expanding heat-health warning systems in just 57 countries could save up to 100,000 lives annually, the UN estimates.
The Asia-Pacific region has already seen a sharp rise in climate-related disasters over the past five decades — from floods and cyclones to landslides and earthquakes — many of which now overlap to create multi-hazard crises.
