Global Challenges/Chemistry Solutions

Confronting Climate Change: “Green” roofs can help fight global warming

October 15, 2009


"Green" roofs, such as the one above, could
fight climate change, scientists report.
Credit: Wikimedia Commons
(High-resolution version)

Summary

How would you like to do your part in helping to slow down global warming? If you live in the city and you like fresh veggies, herbs and flowers, how about planting a garden on your roof? “Green” roofs, those increasingly popular urban rooftops covered with plants, could help fight global climate change, scientists in Michigan are reporting.

 

How would you like to do your part in helping to slow down global warming? If you live in the city and you like fresh veggies, herbs and flowers we have something you’re probably going to like to do: plant a garden on your roof. Scientists in Michigan are reporting that “Green” roofs, those increasingly popular urban rooftops covered with plants, could help fight global climate change. The scientists found that replacing traditional roofing materials with green roofs in an urban area the size of Detroit can dramatically reduce carbon dioxide in the air.

From Michigan State University’s Department of Horticulture, here is Kristen Getter:

“These green roofs help in a number of ways. They not only cut heating and air conditioning costs, for example, but retain and detain stormwater. We knew that green roofs also absorbed carbon dioxide, a major greenhouse gas that contributes to global warming, but nobody had measured the impact until now. The goal of our research was to evaluate the carbon storage potential of extensive green roofs and how much carbon various plants would collect.”

The way the process works is through photosynthesis, which removes carbon dioxide from the atmosphere and stores it in the plants. The process occurs in green plants as carbohydrates are synthesized from carbon dioxide and water using light as an energy source. Most forms of photosynthesis release oxygen as a byproduct. In their study, Getter and her colleagues measured carbon levels in plant and soil samples collected from 13 green roofs in Michigan and Maryland over a two-year period. They found that green roofing an urban area of about one million people would capture more than 55,000 tons of carbon. She puts this in context:

“This is equal to eliminating a year’s worth of carbon dioxide emitted by
10,000 mid-sized SUVs and trucks. This is an enormous amount of pollution
we could take out of the atmosphere. We were surprised what could be
accomplished with the green roofs.”

Besides capturing carbon dioxide and helping with storm water, the greenery also increases the life of roofing materials, improves return on investment compared to traditional roofs, reduces noise as well as air pollution. As a byproduct, the green roofs provide a more aesthetically pleasing environment.

“The beauty of this is that anyone can do it. And today, roof gardens are already popular, so we are optimistic that once people learn how the gardens can help the environment, this kind of urban gardening will spread even faster to cities from coast-to-coast and throughout the world, for that matter.”

Smart Chemists/Innovative Thinking

Smart chemists. Innovative thinking. That’s the key to solving global challenges of the 21st Century. Please check our full-length podcasts on stopgap [Confronting Climate Change] and permanent solutions [Confronting Climate Change II] to this daunting problem. Today’s podcast was written by Michael Bernstein. I’m Adam Dylewski at the American Chemical Society in Washington.