It sounds almost too good to be true doesn’t it? Reducing climate change through a lick of white paint? Actually scientists have long known that white roofs leads to lower cooling costs because they reflect, instead of absorb, heat. According to a study released at the annual Conference on Climate Change by the California Energy Commission, painting a single 1,000 square-foot dark roof white would reduce carbon emissions by 10 metric tons. Changing the color of roofs and pavement in 100 of the world’s largest cities could reduce global emissions by 44 billion metric tons, says Hashem Akbari, a scientist at theLawrence Berkeley National Laboratory in California, who has a campaign to whiten the world’s roofs. Just to compare, the world produced 49 billion metric tons of emissions in 2004, according to the Intergovernmental Panel on Climate Change.
A number of cities have already started implementing this solution: California has mandated all commercial properties with flat roofs be white, and New York is whiting roofs as part of the greening of its transit system. White roofs could cut energy use by buildings by 20 percent, the researchers said. The equivalent energy reduction would save the U.S. $1 billion a year in energy costs.
One concern with this solution is glare. Shiny surfaces are fine for flat roofs, which most people never see, but for other buildings or roads, it might start looking like the Arctic in the summer time, with harsh white light bouncing off bright surfaces. Leading the way, Japanese researchers has tried painting roads with different paints: one’s that reflects infrared light which helps keeps surfaces cool, yet reflects a small proportion – just 23 per cent – of visible light, according to The Guardian. They’ve even done tests with pedestrians, having them stand on the different types of painted roads, and the research subjects seemed to prefer the reflective streets because they were cooler.
Of course, this isn’t a complete solution – emissions are still rising. But a lick of paint for the roofs of 100 of world’s biggest cities would wipe out the expected rise in emissions over the next decade, says Akbari.