Meaning of Earth Hour: Earth Hour is a global event organized by WWF (World Wide Fund for Nature, also known as World Wildlife Fund) and is held on the last Saturday of March annually, asking households and businesses to turn off their non-essential lights for one hour to raise awareness towards the need to take action on climate change. Earth Hour was conceived by WWF and The Sydney Morning Heraldin 2007, when 2.2 million residents of Sydney participated by turning off all non-essential lights. Following Sydney’s lead, many other cities around the world adopted the event in 2008. Earth Hour 2012 will take place on March 31, 2012 from 8:30p.m. to 9:30p.m., at participant’s local time.