Millions of people across the globe switched off their lights for an hour at 8.30pm local time in support of the World Wide Fund for Nature’s Earth Hour initiative.
The lights went out at some of the world's most famous landmarks. Public buildings in the South Korean capital Seoul fell dark for an hour, as did the skyscrapers in Hong Kong's iconic Victoria Harbour.
Ahead of the event, British Prince Charles said Earth Hour was "powerful reminder that together we have the power to change things".
Earth Hour was launched in 2007 in Australia and has since spread around the world. Last year nine million people in the UK alone took part joining a record-breaking chain of 162 countries.
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