By Amy Fleming, Ruth Michaelson, Adham Youssef, Oliver Holmes, Carmela Fonbuena, and Holly Robertson
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The World Health Organisation says that 60% of people will live in cities by 2030, and the more densely populated they become, the hotter they’ll get. Considering that recent predictions warn temperatures in South Asia will exceed the limits of human survival by the end of the century, every degree counts. Even this year, 65 people have perished from nearly 44C (111F) heat in Karachi, Pakistan – a city used to extreme heat.
But the impact is not evenly distributed. For example, there is a strong correlation between an area’s green spaces and its wealth; when shade from tree canopies can lower surfaces’ peak temperature by 11–25°C, “landscape is a predictor for morbidity in heatwaves”, says Tarik Benmarhnia, public health researcher at University of California San Diego. A review paper he recently co-authored found that people living in less vegetated areas had a 5% higher risk of death from heat-related causes.
In 2017, researchers at University of California, Berkeley were able to map racial divides in the US by proximity to trees. Black people were 52% more likely than white people to live in areas of unnatural “heat risk-related land cover”, while Asians were 32% more likely and Hispanics 21%.
Air pollution is more deadly in these areas, too, as nitrous oxides generate ozone when heated by the sun, inflaming airways and increasing mortality risk. “These problems are worse,” says Benmarhnia, “for vulnerable or low-income populations living near traffic in poor housing with no air conditioning.”
But air conditioning will remain out of reach for many, even as it increasingly becomes a necessity. In 2014, Public Health England raised concerns that “the distribution of cooling systems may reflect socioeconomic inequalities unless they are heavily subsidised,” adding that rising fuel costs could further exacerbate this. And when we need to use less energy and cool the planet, not just our homes and offices, relying upon air conditioning is not a viable long-term plan – and certainly not for everyone.
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