British reporters (and Matt Drudge) have been having gentle fun with Energy Secretary Steven Chu's recent remarks that we should paint our roofs white to slow the pace of global warming. But Chu's totally right! The science on this is clear: Replacing black asphalt on roofs, parking lots, and sidewalks with brighter material would reflect more of the sun's rays and do quite a bit to cool the planet. See these two old Vine posts for more.

To give an easy example, just refitting the 30 billion or so square feet of commercial roof space in the United States would be the equivalent of taking roughly 75 million cars off the road for a year. And, as a bonus, buildings with white roofs tend to stay 30 percent cooler than their black-topped counterparts during the summer, which curtails energy use. Obviously this wouldn't stop global warming, but on the list of pain-free measures that would make a fair bit of inroads on the problem, this has to rank very high up there.

--Bradford Plumer