It’s no surprise that cities tend to be warmer than their surrounding areas. They’re full of heat-producing organisms and machines; they’re often built from dark materials; their hard surfaces retain heat. The phenomenon even has its own name: the “urban heat island” effect.
During cold winters, this can helpfully keep temperatures a little higher and prevent snow and ice from sticking to streets. But in summer, it’s a different story: temperatures in cities (especially in naturally hot countries) can climb painfully high.
In Australia, no stranger to heatwaves, a campaign was launched this year to tackle the urban heat island effect. The country’s science agency (CSIRO) found that doubling the number of shady trees to create “green umbrellas” in cities could cut heat wave-related deaths in the elderly by up to 30 per cent. This is partly because the shade prevents direct sunlight from reaching those in public spaces; and partly because greenery has a natural cooling effect. According to the United States Environmental Protection Agency, introducing trees and vegetation can reduce peak summer temperatures by 1- 5°C.