Scientists discover this one simple change could lower temperatures by 3.6 degrees

How do you cool down a major city like London in one easy step? According to new research, the answer is by painting all the roofs white.

This one simple change is the subject of a new study which looked into the best ways to cool down major cities – and the findings show the move could cool the outside temperature of London by 3.6 degrees Fahrenheit (2 degrees celsius).

The study was led by Oscar Brousse, who is a lecturer at University College London.

Brousse said in a statement: "We comprehensively tested multiple methods that cities like London could use to adapt to and mitigate warming temperatures, and found that cool roofs were the best way to keep temperatures down during extremely hot summer days.

"Other methods had various important side benefits, but none were able to reduce outdoor urban heat to nearly the same level."

Reducing temperatures in London is a pressing issue, given that forecasts predict the capital will be three degrees celsius hotter by 2050 in the summer.

Could this be the future of lowering temperatures in London?iStock

A study published in the journal Geophysical Research Letters detailed the research undertaken by experts, including the creation of 3D computer models of London.

They then ran different simulations using data from the hottest days of the summer of 2018 which reached 35 degrees celsius.

They analysed the effects of different strategies in cooling down the city, including installing solar panels, painting roofs white and covering roofs in plants and vegetation.

By far the most impactful was painting roofs white, while adding street vegetation and solar panels made temperatures drop by about 0.5 F (0.3 C).

The authors did concede that there were limitations to the study, given that they didn’t consider the costs of each method and they only studied the outdoor temperature and not indoor.

"Despite these limitations, we expect our results to be at the least indicative of which interventions are capable of producing the greatest cooling effect in London during hot summer days," the authors said in the study.

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