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The Top 10 Green Issues of 2008


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How Carbon Footprints Work
Carbon footprints are numbers that represent the monthly or annual CO2 output measured in tons.
Carbon footprints are numbers that represent the monthly or annual CO2 output measured in tons.
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­You might think your feet stopped growing in high school, but there's a footprint of a sootier variety that's likely to have grown a lot since then. Carbon footprints measure how much carbon dioxide (CO­) you produce in your daily life. Since CO2­ is one of the biggest contributors to global warming, most do-it-yourself environmentalists want to produce less of it. Carbon footprints act as a benchmark -- kind of like a weigh-in before a diet -- so that people striving to reduce or even eliminate their carbon output know where they stand to start with.

­Carbon calculators, programs hosted by a variety of Web sites, turn easy-to-supply numbers like average power use and gas mileage into a single figure: usually a monthly or annual total of CO­ output measured in tons. With such a clear-cut total, it's easy to see the environmental payoff of seemingly small changes like replacing an inefficient appliance or teleconferencing instead of flying to a business meeting. Learn what kind of tracks you're leaving in How Carbon Footprints Work.

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