Who is participating in this tonight? http://www.earthhour.org/ Created to take a stand against the greatest threat our planet has ever faced, Earth Hour uses the simple action of turning off the lights for one hour to deliver a powerful message about the need for action on global warming. About Earth Hour On March 31 2007, for one hour, Sydney made a powerful statement about the greatest contributor to global warming â€“ coal-fired electricity â€“ by turning off its lights. Over 2.2 million Sydney residents and over 2,100 businesses switched off, leading to a 10.2% energy reduction across the city. What began as one city taking a stand against global warming caught the attention of the world. In 2008, 24 global cities will participate in Earth Hour at 8pm on March 29. Earth Hour is the highlight of a major campaign to encourage businesses, communities and individuals to take the simple steps needed to cut their emissions on an ongoing basis. It is about simple changes that will collectively make a difference â€“ from businesses turning off their lights when their offices are empty, to households turning off appliances rather than leaving them on standby.