earth-hour started in Sydney on march 31,2007 .more than 2.2million homes and businesses turned off their lights for an hour.A year later,on March 29,earth hour 2008 became a global activity and was supported by 50 million people from thirty five countries this year,on March28,over2100cities in eight countries took part in it .and the Earth-Hour came to china.Theactivity aims to save energy and improve climate.We may have different ways to spend the hour.Come on!Join us in Earth Hour 2012!