White rooftops might slow climate change, official says

Washington Post

WASHINGTON — Could climate change be staved off by making the United States look like the set of “Mamma Mia!”?

That was suggested in a recent talk by Energy Secretary Steven Chu — although, because he was speaking to Nobel laureates, he did not mention the ABBA musical set in the Greek Islands. He said that global warming could be slowed by a low-tech idea that has nothing to do with coal plants or solar panels: white roofs.

Making roofs white “changes the reflectivity ... of the Earth, so the sunlight comes in, it’s reflected back into space,” Chu said. “This is something very simple that we can do immediately,” he said later.

Chu has brought increased attention to an idea that — depending on your perspective — is either fairly new, or as old as Mediterranean villages, desert robes and Colonel Sanders’ summer suit. Climate scientists say that the reflective properties of the color white, if applied on enough of the world’s rooftops, might actually be a brake on global warming.

White roofs work because of the physics of sunlight. Dark roofs absorb and hold more than 80 percent of solar energy, while white ones can reflect 75 percent of it away.