Join hundreds of millions of people worldwide who are expected to come together to call for action on climate change by doing something really simple — turning off their lights for Earth Hour, 8:30 tonight.

Earth Hour is a global initiative by World Wildlife Fund and symbolizes that by working together, each of us can make a positive impact in this fight to protect future generations.

Participants are encouraged to use social media to ask family and friends to join the movement. Update your Facebook status to tell your friends that you're supporting tonight's event. On Twitter, use hashtags to ensure your tweets are read by as many people as possible (suggestions include #earthhour and #wwfus). Details: www.earthhour.org.