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The Green Life: A New Greenhouse Effect: Global Cooling?

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October 10, 2008

A New Greenhouse Effect: Global Cooling?

Greenhousesspain As shorthand for the insulating effect of certain gases in the atmosphere, "greenhouse" has become somewhat of a dirty word among environmentalists. But according to a study published in the current Journal of Geophysical Research and noted in this week's New Scientist, greenhouses, or hothouse farms, can mask "warming signals." Apparently part of southeastern Spain has so many greenhouses with sunlight-reflecting white roofs that the average local temperature has dropped by an average of 0.54 degrees Fahrenheit per decade since 1983, despite rising temperatures in the rest of the country.

About how many greenhouses are we talking? More than 26,000 hectares, or about 100 square miles, of them. You don't have to be a horticulturalist, however, to save energy and money--and potentially help slow climate change--with a reflective roof. According to the LA Times, roofs account for 25 percent of total surface area in most cities, and pavement accounts for around 35 percent. If 100 major cities covered that space with reflective materials, such as those used on the Spanish greenhouses, it could offset as much as 44 metric gigatons of heat-trapping gases. As Joe Biden would say, let me repeat that: 44 metric gigatons. "That is more than all the countries on Earth emit in a single year," the Times explained in a report on new climate change research last month. "And, with global climate negotiators focused on limiting a rapid increase in emissions, installing cool roofs and pavements would offset more than 10 years of emissions growth, even without slashing industrial pollution."

Even the 1,000 square feet of a typical American home's rooftop can make a difference. To determine what kind of roof will deliver the biggest savings on your energy bill, the Cool Roof Rating Council  recommends considering slope, climate, and state rebate programs. Information on those factors and more can be found at coolroofs.org.

Share your tips: What energy-saving home improvements have you made?

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