The white-shelled roof of the Sydney Opera House fell dark today, one of the first landmarks to turn out the lights in an hour-long gesture to be repeated by millions of people around the world who are calling for a binding pact to cut greenhouse gas emissions.

ICONIC buildings across Ireland turned their lights off and prevented the release of an estimated 30 tonnes of CO2 into the atmosphere during Earth Hour.

From an Antarctic research base and the Great Pyramids of Egypt to the Empire State Building in New York and the Sears Tower in Chicago, illuminated patches of the globe went dark for Earth Hour, a campaign to highlight the threat of climate change.

The floodlit cream shells of the famed Opera House dimmed today as Sydney became the world’s first major city to plunge itself into darkness for the second worldwide Earth Hour, a global campaign to highlight the threat of climate change.

From the Sydney Opera House to Rome’s Colosseum to the Sears Tower’s famous antennas in Chicago, floodlit symbols of civilisation went dark for Earth Hour, a worldwide campaign to highlight the threat of climate change.