NEW YORK, NEW YORK - JULY 29: People try to stay cool on the sweltering streets of Manhattan as the region experiences another heatwave on July 29, 2025 in New York City. Temperatures are expected to reach into the high 90s with a heat index well above 100 degrees. (Photo by Spencer Platt/Getty Images)

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A new global coalition of more than 30 cities has pledged to tackle the issue of extreme heat, which is rapidly becoming one of key impacts caused by climate change.

TheCool Cities Accelerator initiative brings together 33 founding cities, including Austin, Buenos Aires, and Paris to help protect residents, safeguard economies, and redesign cities for a hotter future.

The program has been established by the C40 Cities group, with support from The Rockefeller Foundation, and with implementation support from various groups, including the ClimateWorks Foundation, the Danish Ministry of Foreign Affairs, and IBM.

And it aims to provide a science-based, practical framework for cities to take both immediate and long-term action.

Participating cities have pledged to establish heat leadership and cross-agency governance structures with clear coordination protocols within the next two years.

The signatures have also pledged to introduce activate heat-health awareness outreach and early warning systems informed by climate data to protect vulnerable communities within the same time period.

The initiative also has a series of longer time goals within the next five years, including updating building codes in the cities involved to require safe indoor temperatures sustainably, such as mandating cool or green roofs, improved insulation, or renewably powered active cooling.

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Other long-term goals include creating networks of cool corridors and public spaces by increasing tree canopy, green cover, and shading, cooling or depaving streets, and deploying water features.

Future-proof critical infrastructure for rising temperatures by assessing climate vulnerability and implementing design standards for energy grids, water supply, and public transport.

It comes as a recent report by the Lancet Countdown on Health and Climate Change warned the rate of heat-related mortality has increased 23% since the 1990s, pushing total heat-related deaths to an average 546 000 deaths per year.

According to the study, the average person was exposed to 16 days of dangerous heat in 2024 that would not have been expected without climate change.

It added infants and older adults facing a total of over 20 heatwave days per person, a fourfold increase over the last twenty years.

Amy Buitenhuis, head of heat programs at C40 Cities, said extreme heat is the deadliest weather-related disaster, contributing to an estimated 489,000 deaths globally each year, in an email.

Buitenhius added heat is a silent killer that does not affect everyone equally in cities, and disproportionately harms the most vulnerable.

“Heat also affects a city’s infrastructure, causing disruption in transportation, healthcare systems and power and water access,” said Buitenhuis.

“The economic cost of heat is also significant, disproportionately affecting outdoor workers who are some of the most exposed to extreme temperatures.

“Direct economic losses from heat stress for 12 of the world’s major cities are already estimated at $44 billion annually, a figure projected to nearly double by the 2050s.”

Elizabeth Yee, executive vice president of programs at the Rockefeller Foundation, said the recent Lancet report shared that extreme heat kills about one person every minute, in an email.

Yee added with urban populations growing, and the increased effects caused by urban heat island, the dangers will only continue to grow without more urgent, more coordinated action.

“Although cities are at the epicenter of the extreme heat threat, they can also be where solutions scale fastest,” she said.

“Confronting the urban heat crisis requires strengthening health systems, redesigning infrastructure, and other efforts that require coordination across sectors and borders.”

“What’s more, urban leaders face many of the same challenges, which means the solutions they’re testing are relevant beyond their borders.”

The Mayor of Athens, Haris Doukas said his city is one of the most severely heat-impacted cities in Europe with the number of heatwave days expected to double by 2050, in a statement.

Doukas added Athens has already made great strides in meeting the ambitious goals set by the Cool Cities Accelerator through an innovative heat governance structure.

“Over the next five years, we will continue to transform Athens in alignment with the accelerator, and in collaboration with other leading cities from Europe and all over the world,” said Doukas.