How do we stop our cities from overheating?

Everyone feels it – our cities are getting hotter.

Millions of people are increasingly suffering from frequent heatwaves and the design of our cities is intensifying the problem – with the most vulnerable often the worst impacted.

A new digital solution from Arup – UHeat – has helped us to explore the issue in greater detail than ever before.

Our resulting ‘Urban Heat Snapshot’ reveals how the urban heat island (UHI) effect is pushing up temperatures in cities like London, Madrid, Mumbai and Los Angeles.

The snapshot highlights how:

• temperatures can vary significantly from neighbourhood to neighbourhood
• proximity to nature and vegetation is hugely important
• poorer neighbourhoods are more likely to experience higher temperatures
• employing machine learning and satellite imagery can help identify areas suffering most acutely and model interventions

Did you know?

• x3 expected increase in number of cities exposed to heat above 35°C by 2050
• 61,000 estimated number of deaths in Europe associated with extreme heat in 2022
• 30% increase in tree cover in European cities could have prevented over 2,500 excess deaths

Snapshot insights

The Urban Heat Snapshot analysed the temperature in the urban centres of six cities: Cairo, London, Los Angeles, Madrid, Mumbai, and New York.

At a city level, our work revealed that:

• Madrid had the most severe UHI hot spot, at 8.5°C hotter than its rural surroundings
• UHI can vary drastically neighbourhood to neighbourhood: cities saw up to an 8°C UHI swing within short distances
• In majority of cities, the hottest spots had less than 6% vegetation cover – while the coolest spots in most cities had over 70%
• Three of the cities studied experienced their worst UHI hot spots during the evening or night-time