July 23, 2010

Painting roofs could help save the planet

Global Warming can be delayed by painting roofs and mountains white according to scientists and ecologists from around the world.

A new report by the Lawrence Berkeley National Laboratory in the USA, claims that if all eligible urban flat roofs in the tropics and temperate regions were made white (and sloped roofs to cooler colours) they would offset the heating effect of around 24Gt of carbon dioxide. If true, this would offset the equivalent of the emissions generated by 300 million cars over a 20 year period, but only on a one-off basis.

Publishing their results online in the journal Environmental Research Letters, scientists utilised a conservative assumption for the increase in solar reflective ability of roofs by 0.25 and pavements by 0.15. Covering 50-60% of urban areas, roofs and pavements absorb significant amounts of solar radiation in the form of heat, creating an “urban heat island effect” which makes the cities hotter than their surrounding countryside. This heat contributes to global warming.

In the tropics, cooler houses also require less air conditioning, so painting roofs white could add indirect energy efficiency with the consequent benefit of reducing carbon emissions. Many desert based cultures, including those of the Middle East and ancient Peru, have traditionally used cool coloured roofs and natural breezes to successfully keep their homes from being uncomfortably hot.

Based on a similar scientifically plausible approach, a pilot project to paint recently de-glaciated Andean peaks white again has begun this year in Peru. Starting with Peru’s Chalon Sombrero mountain peak (15,457ft above sea level), Eduardo Gold hopes to reflect solar radiation back into the atmosphere and therefore reduce the effect of global warming on the planet. Locals have already been employed to paint a mixture of lime, egg white and water to cover up to 70 hectares of the Chalon mountain top which has lost its ice cap over the last 40 years as part of a £135,000 project funded by the World Bank.


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