People around the globe have been urged to switch off their lights for an hour as part of a worldwide campaign to highlight the threat of climate change.
Environmentalists hope the Earth Hour initiative will put pressure on governments ahead of a new climate treaty to be signed later this year. Sydney was one of the first cities to plunge itself into darkness earlier on Saturday. While critics remain sceptical, claiming it is purely symbolic, the Earth Hour event also coinicides with European summer time which sees clocks across the continent go forward one hour. Nearly 4,000 cities in 88 countries are taking part – a major increase since the initiative’s inception in 2007.