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.
The environmental group World Wide Fund for Nature urged governments, businesses and households to turn back to candle power for at least 60 minutes starting at 8pm on Saturday wherever they were.
The campaign began last year in Australia and travelled this year from the South Pacific to Europe to North America in cadence with the setting of the sun.
"What's amazing is that it's transcending political boundaries and happening in places like China, Vietnam, Papua New Guinea," said Andy Ridley, executive director of Earth Hour.
Earth Hour officials hoped 100 million people would turn off their non-essential lights and electronic goods for the hour. Electricity plants produce greenhouse gases that cause climate change.
In Chicago, lights on more than 200 downtown buildings were dimmed, including the stripe of white light around the top of the John Hancock Centre. The red-and-white marquee outside Wrigley Field also went dark.
New Zealand and Fiji were first out of the starting blocks this year. And in Sydney, Australia - where an estimated 2.2 million people observed the blackout last year - the city's two architectural icons, the Opera House and Harbour Bridge, faded to black against the backdrop of a lightning storm.
Lights also went out at the famed Wat Arun Buddhist temple in Bangkok, Thailand; shopping and cultural centres in Manila, the Philippines; several castles in Sweden and Denmark; the parliament building in Budapest, Hungary; a string of landmarks in Warsaw, Poland; and both London City Hall and Canterbury Cathedral in England. Greece, an hour ahead of most of Europe, was the first on the continent to mark Earth Hour. On the isle of Aegina, near Athens, much of its population marched by candlelight to the port.
Much of Europe - including France, Germany, Spain and European Union institutions - planned nothing to mark Earth Hour.