What began as an entertaining online feature has evolved into an active virtual community that’s pledged to reduce carbon emissions by millions of pounds.

Last May, National Grid launched an interactive Website that let users play games, adopt virtual polar bears and pledge variou actions to reduce their carbon footprints. Since then, tens of thousands of people have visited the site and committed to cutting their carbon emissions by more than 52 million pounds — as much as is produced annually by 4,200 cars.

The site’s polar bear, Floe, has also generated international attention.

“We are absolutely thrilled to see how popular the Floe Web site has become,” said Tom King, president of National Grid in the US. “Floe’s friends continue to illustrate the tremendous impact that can result from the collective power of our actions.”

The site helps users visualise their impact on the environment by increasing the size of Floe’s virtual iceberg as they pledge to use energy-efficient products or take showers instead of baths.

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