Cities in the Philippines are among those in East Asia with the hottest climate, threatening to decrease economic production and cause the death of over 100,000 people in the region, the World Bank said Thursday.

These are the findings revealed in its new report entitled "Unlivable: What the Urban Heat Island Effect Means for East Asia's Cities" which identifies Quezon City as having the hottest climate among Philippine cities.

Within East Asia, the top 10 cities with the same climate as Quezon City's are also seen in Indonesia, Malaysia and Singapore.

The World Bank said their higher temperatures are caused by urban heat island or the UHI effect which is the result of heat from tropical weather worsened by the rise of concrete structures compared to greenery.

Amid climate change, the World Bank said extreme heat could become more severe.

"Overall, the results are sobering. Already more than 100,000 people in East Asia die each year because of extreme heat," the multilateral lending institution said.

Heat-related deaths

It warned that "projections indicate that climate change will further increase heat-related mortality during this century."

UHI-affected cities, especially poor neighborhoods, have higher land surface temperatures of up to 6.6 degrees Celsius compared to nearby provinces.

"While initially it may seem counterintuitive, for cities generally, the UHI effect is typically stronger at night than during the day. This is because heat stored in the built environment is gradually released after sunset," the World Bank said.

Aside from numerous deaths, the World Bank said extreme heat in Southeast Asia lowers labor productivity, resulting in reduced gross domestic product by 5.5 percent to 6 percent by 2030.

For the Philippines, GDP losses could reach 5.9 percent or $85 billion, lower than Indonesia's 6 percent or $250 billion.

Less livable cities

"Finally, extreme urban heat makes cities less livable both directly through the unpleasantness of extreme heat — especially when combined with high humidity — and indirectly through other negative impacts, such as potential increases in crime, violence, and motor vehicle accidents," the World Bank added.

To prevent the UHI effect from growing, the World Bank recommends planting more trees and other plants in urban areas, and the construction of shaded areas and separately-spaced buildings or wind spaces through better urban planning and design.

The World Bank also suggests the creation of heat reduction policies by the local government units and firms, and the distribution of healthcare to vulnerable groups, such as children, senior citizens, field-based workers, and persons with disabilities.

"Extreme heat is a challenge that requires coordinated action across city government institutions working in tandem with local stakeholders such as employers and neighborhood associations," the World Bank said.