It’s never been so simple to change the world. All it takes is a flip of the switch. This Saturday, March 27, WWF is encouraging everyone around the world to make a statement about their concern for climate change by turning off their lights.

The Las Vegas Strip went dark. So did the Empire State Building, Sydney’s Opera House, St. Louis Arch and the Great Pyramids among other well-known world landmarks. Since its inception three years ago, Earth Hour has become a global phenomenon. Last year nearly one billion people worldwide, including 80 million Americans, participated in Earth Hour.

So if you’re inclined to show your support, turn off your lights this Saturday at 8:30 p.m. local time, and make a statement that you care about the Earth. Don’t forget to let others know that you’ll be participating by visiting www.myearthhour.org.