White roofs may successfully cool cities

Painting the roofs of buildings white has the potential to significantly cool off cities and mitigate some impacts of global warming, results of a new study indicate.

A construction crew paints a white roof in downtown Washington, D.C. Credit: Maria Jose-Vinas, American Geophysical Union

The research, the first computer modeling study to simulate the impacts of white roofs on urban areas worldwide, suggests there may be merit to the idea of turning roofs white.

But the study team, led by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., cautions that there are still many hurdles between the concept and actual use of white roofs to counteract rising temperatures.

"Our research demonstrates that white roofs, at least in theory, can be an effective method for reducing urban heat," says NCAR scientist Keith Oleson, the lead scientist on the study. "It remains to be seen if it's actually feasible for cities to paint their roofs white, but the idea certainly warrants further investigation."

Results of the research are slated for publication later this winter in the American Geophysical Union (AGU) journal Geophysical Research Letters.

The work was funded by the National Science Foundation (NSF), NCAR's sponsor. "Climate change mitigation research is an extremely important topic," says Steve Nelson, NSF programme director for NCAR. "Whether on white roofs or other climate change mitigation subjects, it's important to consider the many feedbacks and complicating considerations that make research in this area very complex."