Earth Hour 2010

Beginning in Sydney, Australia three years ago, Earth Hour has grown into a global observance. States, large organizations and individual people observed Earth Hour 2010 on Saturday March 27th, as homes, office towers and landmarks turned off their lights for an hour starting at 8.30 pm local time to raise awareness about climate change and the threat from rising greenhouse gas emissions. Collected here are a series of before-and-after photographs from this year - which (starting with the second one below) will fade between 'on' and 'off' when clicked.

These two photos show Malaysia's landmark Petronas Twin Towers before, left, and after being turned off its lights to mark Earth Hour in Kuala Lumpur, Malaysia, Saturday, March 27, 2010. (AP Photo/Lai Seng Sin)