Geo-Engineering Cities Using White Roofs and Pavements

The long-term effect of increasing the albedo of urban areas (11 page pdf, Hashem Akbari, H Damon Matthews, Donny Seto, Environmental Research Letters, Apr. 12, 2012)

Also discussed here: Resurfacing Urban Areas to Offset 150 Billion Tons of CO2 (ScienceDaily, Apr. 13, 2012)

Today, we review a look at changing the albedo of urban areas of the world and then estimating how much this would reduce climate warming in terms of offset CO2. The key “dark”, and therefore highly absorbing, surfaces of most cities are the black roofs and pavements which make up 60% of the area and are normally replaced every decade or two. By increasing the albedo of urban areas in a global climate model and running a simulation for 80 years ahead, the authors estimated a CO2 offset of between 130 and 150 billion tones- equivalent to taking every car in the world off the road. These reductions could be put into effect by changes at the municipal level with benefits in terms of reduced urban heat islands and urban smog.  
Key Quotes:

 “increasing the albedo of the urban areas and human settlements (hence increasing the albedo of Earth as a whole) by increasing the reflectivity of artificial urban surfaces (rooftops, pavements), is based on proven technologies that have been used for centuries with no known negative effect”

 “Pavements and roofs comprise over 60% of urban surfaces (25% roof and 35% pavement)”

“We used the University of Victoria Earth System Climate Model (UVic ESCM), an intermediate complexity global climate model which includes an interactive global carbon cycle.. as a spatially explicit model with reduced atmospheric variability, this model is well suited to assess the climate response the small and spatially variable forcing associated with urban surface albedo modification”

 “increasing the reflectance -- commonly known as albedo -- of every urban area by 0.1 will give a CO2 offset between 130 and 150 billion tonnes. This is equivalent to taking every car in the world off the road for 50 years CO2”

 "Typically roofs are resurfaced (or changed) about every 20-30 years; paved surfaces are resurfaced about every ten years. When roofs or paved surfaces are installed, they can be changed to materials with high solar reflectance, typically at no incremental cost,"

 “Cool roofs save air conditioning energy and reduce CO2 emissions. Cool roofs and cool pavements (Cool Cities) reduce the urban heat island, improve comfort, and reduce urban smog”

 “We propose customizing local ordinances, standards, policies and programs to promote the use of white or light color urban surface materials as they are replaced”

Related articles

• Lighter roofs and roads would offset 130 to 150 billion tons of CO2 (nextbigfuture.com)
• How to Adapt to Any Climate Change - Global Warming or Cooling - and Save Money In the Process (truth11.com)
• How to Beat Global Warming ... Or a New Ice Age (zerohedge.com)
• How to Beat Global Warming ... Or a New Ice Age (washingtonsblog.com)
• Resurfacing urban areas to offset 150 billion tons of CO2 (eurekalert.org)
• Global model confirms: Cool roofs can offset carbon dioxide emissions and mitigate global warming (eurekalert.org)
• Whitening Cities' Roofs Is Environmental Equivalent of Taking 300 Million Cars Off the Road, DoE Study Says (popsci.com)
• Bright is the new black - multi-year performance of high-albedo roofs in an urban climate (pubs.giss.nasa.gov)
• Global warming scientists foresee Sun-reflecting cities (rawstory.com)
• ScienceShot: Bright Roofs, Cool World (news.sciencemag.org)