Thursday, January 15, 2009

Get Out Your Brushes

How white paint could help postpone climate crisis

Could the planet’s rising temperatures and tides be stemmed by something as simple as white paint? Of course not. But according to a soon to be published study in the journal Climatic Change, a few million buckets could buy the world a few crucial years.

Here’s the premise: if all the rooftops and paved surfaces in the world’s major cities were painted white or replaced by more reflective material (like roads made of concrete rather than asphalt), the global cooling effect would be enormous. Big enough, the study shows, to delay climate change by about 11 years.

They started off by calculating that changing a 1,000 square foot roof—the average size on an American home—from black to white would essentially offset the heating effects of 10 metric tons of carbon dioxide emissions. (Conveniently, and coincidentally, 10 metric tons is about the amount that a typical American home emits over the course of a year.) And that’s just one building. Collectively, the concentration of hard, dark surfaces causes the “urban heat island” effect, which can make cities an average of 5 degrees Fahrenheit—and up to 20 degrees F—warmer than surrounding areas. And even though cities cover less than 1 percent of the world’s land surface, Dr. Akbari and California Energy Commissioner Arthur Rosenfeld, two of the country’s leading experts on urban heat island mitigation, emphasize that the collective impact is significant. A global “cool roofs and cool pavement” strategy, they argue, would increase the global albedo (or reflectivity, if you’ve forgotten your high school physics) enough to reduce planetary warming by the same amount that releasing 44 billion tons of carbon dioxide released to the atmosphere would increase it.

Read Ben Jervey's post (including cool graphs) at

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