Started in Sydney, Australia in 2007, Earth Hour quickly grew into a global observance. More than 1,000 cities in over 80 countries observed Earth Hour 2009 on Saturday March 28th, 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. Enjoy!
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