Earth Hour 2013

Earth Hour is an annual global event at which hundreds of millions of households, businesses and governments around the world turn off their lights for one hour in order to call attention to the need of action on climate change.

It is the biggest environmental event ever held and organized by the World Wildlife Fund (WWF).

Earth Hour began as a one city initiative in 2007, with more than 2.2 million residents of Sydney switching off their lights to call for action on climate change.

It has since become the world's largest action for the environment, in 2012 reaching a record breaking 7001 cities and towns in 152 countries and territories across all seven continents.