More good news from the front lines, some solid estimates of capabilities of green roofs to sequester carbon! I can almost see the CCURB proposals… or maybe the 2010 Mayor’s Green Summer Job Corps.
From Miller-McCune.com: 
In a first-of-its-kind study, researchers at Michigan State University have calculated the carbon sequestration benefits extensive green roofs can provide. Findings from horticulturalists Kristen Getter and Brad Rowe in October’s Environmental Science & Technology revealed green roofs’ potential as carbon sinks.
… Two experiments were run to measure the potential of storing carbon in green roofs…All the green roofs were planted with Sedum, a genus of leafy succulent known for its hardiness and often used as ground cover. “We planted what we knew would grow,” said Getter.
Over a two-year period, the plants on the East Lansing campus were periodically harvested. Leafy parts stored on average 168 grams of carbon per square meter, the roots and the soil respectively stored 160 and 300 grams on average. Combined, each plot had the capacity to store 375 grams of C02 per square meter.
The researchers estimated the city of Detroit has 219 acres of roof space available for conversion. If black tar roofs were retrofitted, 55,000 tons of CO2 could be removed from the air — enough CO2 to offset the carbon emissions of 10,000 mid-sized SUVs or trucks for an entire year, they calculated.
And some straight-up economic benefits:
Inside his office, Mumford has noticed a marked difference. White noise has been reduced. He’s saved 23 percent on his electric bills. And rather than redoing his roof every 10 to 20 years, he believes his green roof can last up to 60 years if maintained properly.
A study by the Berkeley Lawrence Lab found that if 15 percent of the buildings in Los Angeles installed reflective or green roofs, daytime temperatures would be reduced by 3 degrees Celsius — saving Los Angeles half to 1 gigawatt of power during peak-use hours.
