Global Capitals at Rising Risk from Extreme Heat

By Staff, Agencies

A recent assessment published by the International Institute for Environment and Development [IIED] finds the world’s busiest capitals are facing a sharp rise in extreme heat, with 35°C days far more common since the 1990s.

The report shows 43 major capitals averaged 1,335 extreme heat days annually from 2015–2024, up from 1,062 in the early 2000s. Cities like Rome and Beijing saw hot days’ double, Manila tripled, and Madrid jumped from 25 to 47. Even London now sees twice as many 30°C+ days.

IIED researcher Anna Walnycki told The Guardian that global temperatures are rising faster than governments anticipated — and even faster than they’re responding. Without urgent action, she warned, millions in urban areas will face growing risks due to cities’ heat-trapping effects.

Walnycki emphasized that the urban poor are hit hardest worldwide. “The poorest will suffer most—whether in London, Luanda, or Lima,” she said, adding that the impact is far worse in low-income or informal communities in the Global South due to poor housing conditions.

"Climate change is the new reality. Governments can't keep their heads buried in the sand any more."

The report comes amid record-breaking heat driven by fossil fuel emissions. Japan hit 41.2°C in July 2024, hospitalizing over 10,000, while Europe saw 16,500 heat-related deaths. Cities like Shanghai and Dallas now face extreme heat and sudden downpours—so-called “climate whiplash.”

The data, covering 40 major capitals and three key cities, shows sharp warming even in once-cool areas. Brasília went from 3 to 40 days over 35°C annually, while Pretoria rose from 3 to 11.

The Global Center on Adaptation launched The Heat is On campaign to fast-track vital measures like shaded public spaces, climate-smart work schedules, and cooling centers.

"Extreme heat is not a distant risk – it is here now, threatening our people, our economies and our future," said Macky Sall, GCA chair and former president of Senegal. "By investing in practical, proven solutions, we can protect our citizens."

Yet in places like the UK, governmental responses have been criticized as fragmented and insufficient. In April, official climate advisors described current heat-preparedness efforts as "inadequate, piecemeal and disjointed."

Walnycki warned, “Heatwaves keep many of us awake, sweating. This isn’t a problem fixed by air conditioning alone. Cities urgently need funding for better insulation, ventilation, heat plans, and shade.”