paint your roof white

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Two years ago, Barack Obama’s top man on global warming, Professor Steven Chu, the US Secretary of Energy, suggested at the Royal Society in London that one of the most effective engineering measures to tackle rising temperatures is to paint roofs.

He estimated that a city or town where the roofs and the pavements and roads have light-coloured 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.
The Independent, 13 Apr 2012

don’t paint your roof white

The land covered by urban areas more than doubled between 1992 and 2005, to about 0.128% of Earth’s surface, Mark Z. Jacobson and John E. Ten Hoeve of Stanford University report in the Journal of Climate. A worldwide conversion to white roofs, they found, could actually warm the Earth slightly due a complex domino effect.

Although white surfaces are cooler, the increased sunlight they reflect back into the atmosphere by can increase absorption of light by dark pollutants such as black carbon, which increases heating.
The Guardian, 27 Oct 2011
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