Some of the world's biggest cities went dark in the name of Earth Hour on Saturday night.
Organised by the World Wide Fund for Nature (WWF), Earth Hour encourages people to turn off their lights between 8.30pm and 9.30pm in the name of conservation.
"Nature not only provides us with all the things we need to live – from the air we breathe to the water we drink, and from the shelter we need to the economy we rely on – but also makes our lives better. However, its growing loss puts this all under threat," said Earth Hour's official website.
It began in Sydney in 2007 Earth Hour says it is "now the world's largest grassroots movement for the environment, inspiring millions of people to take action for our planet and nature".