Baby, It’s Hot Outside! Extreme Heat Is Having An Impact On World Cities.

A statistical analysis by the International Institute of Environment and Development found the number of days of extreme heat in major world cities is increasing at an alarming rate. The IIED defines extreme heat as 35°C (95°F) or above. Most people would agree that such temperatures are indeed dangerous, especially for people who are sick, elderly, or unable to access air conditioning. The Institute says:

“In 2024, the hottest year on record, the world’s 40 most populous capital cities and…three extras saw their highest total of days reaching 35º C in the period analysed, at 1,612. This was 196 more than the next-highest total of 1,416 days in 2019. In 2023 there were 1,410 very hot days, the third-highest tally. The three years with the highest total days of extreme heat have all occurred since 2019, showing that adapting cities to climate change is only becoming more important.

“Nine cities — just over a fifth — of the 43 surveyed experienced their highest number of very hot days for the past 31 years in 2024. They were: Antananarivo (Madagascar), Cairo (Egypt), Johannesburg (South Africa) , Kinshasa (Democratic Republic of Congo), Manila (Philippines), Rome (Italy), Tokyo (Japan), Washington DC (USA). and Yaoundé (Cameroon). Four cities saw their second highest number of very hot days in the 31-year period in 2024: Beijing (China), Jakarta (Indonesia), Santiago (Chile), and Seoul (South Korea).

“The total number of days over 35º C in 2024 (1,612) was 52 percent higher than in 1994 (1058), across the 43 surveyed cities. The average number of days over 35º C in these cities has risen by 26 percent in the 31 year period studied, from an average of 1,062 per year between 1994 and 2003 to 1,335 per year between 2015 and 2024.”

The Guardian does not mince its words when reporting on this study. It says clearly, “Global heating caused by fossil fuel burning is making every heatwave more intense and more likely. Extreme heat is likely to have caused the early death of millions of people over the past three decades, with elderly and poor people in fast-growing cities most deeply affected.” It adds that many world cities are also dealing with “climate whiplash” that brings deadly swings between extreme wet and dry weather.

“Global temperatures are rising faster than governments probably expected and definitely faster than they seem to be reacting,” Anna Walnycki, an IIED researcher, told The Guardian. “Failing to adapt will condemn millions of city dwellers to increasingly uncomfortable and even dangerous conditions because of the urban heat island effect.”

Those with fancy houses and air conditioning won’t be the ones to suffer most, of course. “The poorest people will likely suffer the most whether they’re in London, Luanda, or Lima, but the impacts will be significantly worse in low income or unplanned communities in the global south thanks to lower quality housing,” she added. She noted that a third of the world’s city dwellers live in slums or informal settlements. “Climate change is the new reality. Governments can’t keep their heads buried in the sand any more.”

Who’s Afraid Of The Big, Bad Heat?

Well, maybe. The government of the United States is running around the world screaming that we must burn more coal, more methane, more LNG, and more gasoline because we owe it to the fossil fuel industry to let them maximize their profits. If you see a stark disconnect from reality in that policy, you are not alone.

On September 26, 2025, the Global Center on Adaptation announced is latest campaign, known as The Heat is On, which is designed to accelerate the adoption of strategies that save lives and protect livelihoods — from cooling centers and shaded rest areas, to work schedules that reduce exposure to the heat and early-warning systems.

Putting Heat On The UK Government

In April, the government’s preparations to protect people from the escalating impacts of the climate crisis were condemned as “inadequate, piecemeal and disjointed” in a report to Parliament prepared by the Climate Change Committee in the UK. In the executive summary of that report, the Committee said:

“The increasing impacts of climate change are clear, both globally and in the UK. Adaptation is needed now to ensure that the UK is prepared for today’s extreme weather as well as the rapidly increasing severity of future risks. The costs of these impacts are already being felt, and the risks will continue to grow even if international targets to limit global warming are met. Action is needed now whilst we still have the opportunity to address these risks in a way that is both cost-effective and timely.

“Delivery of effective adaptation remains limited and, despite some progress, planning for adaptation continues to be piecemeal and disjointed. The vast majority of our assessment outcomes have the same low scores as in 2023. In terms of adaptation delivery, we do not find evidence to score a single outcome as ‘good’. Adaptation progress is either too slow, has stalled, or is heading in the wrong direction.

“Whilst there is some evidence of policies and plans improving, it is clear that NAP3 has been ineffective in driving the critical shift towards effective delivery of adaptation highlighted in our previous progress report in 2023.

“The Government has yet to change the UK’s inadequate approach to tackling climate risks. The current government’s manifesto promised to ‘improve resilience and preparation across central government, local authorities, local communities, and emergency services’.

“It inherited a NAP that fell short of the task of preparing the UK for the climate change we are experiencing today, let alone that coming in the future. Our assessment finds little evidence of a change of course. The slow pace of change indicates that adaptation is not yet a top priority across government.”

That is a pretty damning report, and yet the UK government is being pressured by politicians and representatives of the fossil fuel industry to drill more oil and gas wells in the North Sea and to build more hugely expensive nuclear power plants instead of putting resources and incentives into installing more renewables like wind and solar.

Cover photo: IIED