California Center for Sustainable Energy

Hundreds of thousands of people across the globe have already signed up to flip their light switches off at the end of March for Earth Hour 2009. Last year’s event was the largest voluntary power-down ever, when more than 50 million people in 35 countries turned off their lights for 60 minutes.

The campaign started in Sydney in 2007, and the city’s carbon consumption dropped by more than 10 percent during Earth Hour that year. If Sydney maintained that level of energy reduction year-round, it would be the equivalent of taking almost 50,000 cars off the road. To pledge your participation, sign up at earthhour.org, and on March 28th join your fellow world citizens and go dark between 8:30 and 9:30 p.m. San Diego time.

Watch the beautiful Earth Hour Photos from around the globe.