Extreme heat intensifies in world’s cities

October 01, 2025 (MLN): The world’s largest capital cities are now enduring 25% more days of extreme heat each year than they did in the 1990s, according to APP.

In 2024, the International Institute for Environment and Development (IIED) reviewed rising levels of heat in 20 of the world’s most populous capitals over the past three decades (1994–2023).

The study found a steady increase in the number of days hitting 35C or above.

The updated research expands the scope to 40 capitals and includes temperature data from 2024, which the World Meteorological Organization confirmed as the hottest year on record.

From Washington DC and Madrid to Tokyo and Beijing, the analysis revealed a sharp rise in extremely hot days as the climate crisis worsens.

On average, the 43 capitals assessed saw 1,062 days per year above 35C between 1994 and 2003, rising to 1,335 days between 2015 and 2024.

The rise was widespread. Rome and Beijing now see twice as many scorching days as before, while Manila has seen its tally triple.

Madrid now records an average of 47 days above 35C each year, compared with 25 in the past. Even London, known for its cooler climate, has seen the number of days above 30C double.

“Global temperatures are rising faster than governments probably expected and definitely faster than they seem to be reacting,” said Anna Walnycki, a researcher at IIED.

“Failing to adapt will condemn millions of city dwellers to increasingly uncomfortable and even dangerous conditions because of the urban heat island effect.”

She added that impacts will be especially severe in low-income and unplanned urban areas in the global south, where housing quality is poor and around a third of city residents live in slums or informal settlements.

The worsening heat is driven by global warming caused by burning fossil fuels. Scientists warn that every heatwave is now made more intense and more likely as a result.

Despite international agreements, emissions continue to rise, when they must fall by 45% by 2030 to keep global temperature increases within the Paris Agreement’s 1.5C limit.

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