27 March 10: Earth Hour, a global call to action on climate change, took place on 27 March 2010, from 8:30-9:30 pm (local time).
Earth Hour started in 2007 in Sydney, Australia, when 2.2 million homes and businesses turned their lights off for one hour to make their stand against climate change. In 2008, Earth Hour became a global sustainability movement, with more than 50 million people across 35 countries participating. UN Secretary-General Ban Ki-moon noted that the event asked the world to turn off its lights to serve as both a “warning and a beacon of hope.” [UNEP Press Release]