As the threat of global warming becomes widely recognized, scientists have proposed using geoengineering (manipulation of the Earth’s environment) to quickly respond to this threat. Most proposed geo-engineering techniques are novel and unproven. Two simple technologies that have been around for thousands of years, cool roofs and cool pavements, should be the first geoengineering techniques used to combat global warming.

Increasing the solar reflectance of urban surfaces reduces their solar heat gain, lowers their temperatures, and avoids transferring heat back into the atmosphere. This process of “negative radiative forcing” counters global warming. In a recent study to be published in journal Climatic Change, Akbari, Menon and Rosenfeld have calculated the CO2  offset, or equivalent reduction in CO2 emission, achieved by increasing the solar reflectance of urban surfaces.

Akbari, Hashem, Surabi Menon, and Arthur Rosenfeld. “White Roofs Cool the World, Directly Offset CO2 and Delay Global Warming .” LBNL Heat Island Group. (2008).