KARACHI: Extreme heat in Pakistan is transitioning from short, episodic spikes to chronic, season-long and potentially year-round hazards, with Karachi emerging among Asia’s hottest megacities, the UN’s Economic and Social Commission for Asia and the Pacific (ESCAP) has warned in a new report.

The Asia-Pacific Disaster Report 2025 warns that Pakistan will face a twin climate threat: soaring urban temperatures caused by the “urban heat island” effect and a dramatic geographic expansion of severe and extreme heat across the country, shifting dangerous temperatures from short bursts to chronic seasonal or even year-round hazards.

The findings come as Pakistan grapples with intensifying climate shocks, from record-breaking heatwaves and droughts to devastating floods. As a lower-income country with a rapidly growing urban population and high outdoor labor dependence, Pakistan is expected to bear disproportionate impacts of rising temperatures on public health, food production, energy systems and vulnerable communities.

ESCAP’s assessment places Pakistan among the region’s highest-risk countries for agricultural heat stress, alongside Bangladesh, India, Afghanistan and Nepal, while also identifying it as part of the High Mountain Asia zone where glacial melt and flood risk are accelerating. The report underscores that without structural reforms, current reactive policies are insufficient to cope with the scale of future climate-driven heat hazards.

“Many Asian cities such as Seoul, Tokyo, Beijing, Delhi, Karachi, Dhaka, Manila, Jakarta and Phnom Penh are projected to be substantially hotter in the years ahead, with this effect adding an extra 2°C–7°C on top of global warming,” the UN report said, highlighting the extreme threat facing Pakistan’s cities.

The report also warns that extreme heat will no longer be an occasional event but a persistent national hazard: “The number of days exceeding the critical thresholds of 35°C or 41°C will rise substantially… transforming what were once episodic events into chronic seasonal or even year-round hazards.”

Karachi, one of the world’s most densely populated megacities, is singled out as highly exposed due to its built-up surfaces, limited green cover, and unequal access to cooling and health care. The report says children, the elderly, and outdoor workers in low-income neighborhoods will face the worst impacts as temperatures rise.

The additional 2–7°C caused by the heat island effect could overwhelm health systems, strain water supplies and widen inequality between hotter, poorer areas and wealthier, greener districts.

Under high-emission climate scenarios, ESCAP finds that Pakistan’s plains, including Sindh, Punjab and southern Balochistan, will see a sharp rise in days above 41°C, a level classified as “extreme danger” where heat stroke becomes likely with prolonged exposure. Rural regions already struggling with water scarcity and poverty are expected to see large labor productivity losses, deepening socio-economic vulnerabilities.

ESCAP’s Agricultural Heat Stress Score places Pakistan in the highest-risk category for heat impacts on crop yields and livestock. Rising temperatures are expected to sharply erode agricultural productivity, threatening staples such as wheat and rice.

The report also notes that Pakistan’s energy grid, already prone to summer overload, will face greater instability as power plants operate less efficiently in extreme heat while cooling demand continues to surge.

In northern Pakistan, glacial melt poses another long-term danger, with ESCAP warning of growing risks from glacial lake outburst floods affecting millions across High Mountain Asia.

ESCAP cautions that Pakistan, like most countries in the region, relies heavily on short-term, reactive measures, including emergency adviseries and relief operations. It calls for a shift toward heat-resilient urban planning, early warning systems, worker protection frameworks and nature-based cooling solutions.

Without such reforms, the report says, rising heat will continue to amplify inequality, disrupt livelihoods and impose severe economic costs nationwide.