Will You Turn Your Lights Out for Earth Hour today?

Today, as part of a global call for action on climate change, hundreds of millions of people and tens of thousands of organizations will go dark for one hour from 8:30-9:30 p.m.

Earth Hour is a global World Wildlife Fund initiative that began in Sydney in 2007, when 2 million people switched off their lights. In 2008, more than 50 million people all over the world took part in the action. In 2009, almost 1 billion people worldwide switched off their lights. And, in 2011, Earth Hour involved 135 countries with more than 1.8 billion people participating.

According to organizers, hundreds of landmarks across more than 5,000 cities and towns will go dark at 8:30 p.m. local time, with Libya, Algeria, Bhutan and French Guinea among those participating for the first time.

This year, Earth Hour launched the "I Will If You Will" campaign to to try to create sustainable action beyond the hour. Thousands of individuals, organizations and governments have created an "I Will If You Will" challenge, inspiring their friends, colleagues and networks to be a part of their action towards a more sustainable world.