Painting roofs white and using light-colored materials to surface roads and pavements would not only make cities cooler in summer, it would save the same amount of carbon as taking all the cars in the world off the roads for 50 years.
One of the simplest, yet most effective, ways of engineering the urban environment to cope with global warming is to increase the reflectivity of the cityscape so that more of the incoming sunlight is directed back into space.
City buildings in warm climates with “cool colored” surfaces that reflect infra-red radiation would also be cooler than traditional buildings and so would conserve energy – and carbon – that would otherwise be used on air conditioning.
Increasing solar reflectance or “albedo” has been suggested as a way of combating the “heat island” effect of towns and cities, where summers are made unbearably hotter in built-up areas by Tarmac roads and dark buildings that absorb sunlight.
[It is] estimated that a city or town where the roofs and the pavements and roads have light-colored surfaces can increase their albedo by about 10 per cent, which globally would provide a CO2 offset of between 130 billion and 150 billion tonnes – the same as taking every car in the world off the road for 50 years.
Albedo is measured on a scale of zero to one, where 1.0 is totally reflective and zero absorbs all sunlight.
The researchers believe that it would be cheap and easy to increase the albedo of cities by applying the reflective materials when roofs and roads are routinely resurfaced, rather than doing it as a special measure.