A recent Journal of Climate paper by Stanford’s Mark Jacobson and John Ten Hoeve (2011) on urban heat islands and cool roofs is a useful contribution to the literature. However, their results regarding white roofs are preliminary and uncertain. Along with work at the Lawrence Berkeley National Lab, other published papers have addressed the broader benefits of white roofs. These studies taken together raise important issues that need to be considered from a policy standpoint to fully understand the potential of more reflective (white or cool) surfaces.

A new study from Lawrence Berkeley National Laboratory (Berkeley Lab) breaks new ground by using a high-resolution model of the continental United States that incorporates land-surface feedback to probe the effects of deploying light-colored roads and rooftops. Berkeley Lab researchers Dev Millstein and Surabi Menon found that atmospheric feedback—such as changes in cloud cover or precipitation—does have an important effect, resulting in different amounts of cooling in different cities, but that cool roofs and pavements are still beneficial for combating global warming.

Paris may have the Eiffel Tower and London has its Big Ben, but Lawrence Berkeley National Laboratory has the iconic domed roof of the Advanced Light Source. Now the ALS is getting a new roof—and not just any roof but a cool roof that will reflect sunlight back into the atmosphere, thus playing a small part in mitigating global warming.