Towns and cities around the world are turning out the lights for an hour to highlight the threat of climate change.
Towns and cities around the world are turning out the lights for an hour to highlight the threat of climate change.
"Earth Hour" began in Sydney at 2000 local time (0900 GMT), when lights went out on landmarks like the Opera House and Harbour Bridge.
Sydney was the first major city to begin "Earth Hour", when at 2000 (0900 GMT), lights went out on landmarks like the Opera House and Harbour Bridge.
Bangkok, Toronto, Chicago and Dublin are among 27 other cities officially due to follow suit at 2000 local time.
Bangkok, Toronto, Chicago and Dublin are among 27 other cities officially due to follow suit at 2000 local time.
But critics have dismissed the event as a gimmick that will not make any difference, a BBC correspondent notes.
But critics have dismissed the event as a gimmick that will not make any difference, a BBC correspondent notes.
The initiative began in Sydney last year when an estimated two million residents took part, cutting energy usage by more than 10% for the hour.
The initiative began in Sydney last year when an estimated two million residents took part, cutting energy usage by more than 10% for the hour.
Organisers expect hundreds of towns and cities across the world to take part in the event and hope some capitals not officially involved, such as London and Rome, will mark the event by dimming lights on some landmarks.
Organisers expect hundreds of towns and cities across the world to take part in the event and hope some capitals not officially involved, such as London and Rome, will mark the event by dimming lights on some landmarks.
In its own contribution, the Google web search engine is putting a dark background on its homepage.
In its own contribution, the Google web search engine is putting a dark background on its homepage.
Top emitter
Top emitter
Organisers insist the aim of Earth Hour is to show that communities care passionately about climate change and want to keep up the pressure on governments to act decisively.
Organisers insist the aim of Earth Hour is to show that communities care passionately about climate change and want to keep up the pressure on governments to act decisively.
Andy Ridley of the WWF, which is behind the initiative, says interest has been immense.
Andy Ridley of the WWF, which is behind the initiative, says interest has been immense.
"We're aware of villages in Norfolk in England that are doing Earth Hour and we're aware of the big cities like Chicago and Sydney that are doing it," he told the BBC.
"We're aware of villages in Norfolk in England that are doing Earth Hour and we're aware of the big cities like Chicago and Sydney that are doing it," he told the BBC.
Celebrations in Australia to mark Earth Hour include traditional Aboriginal torchlight performances, environmentally friendly dinner parties and special candlelit evenings for single people, the BBC's Phil Mercer reports from Sydney.
Celebrations in Australia to mark Earth Hour include traditional Aboriginal torchlight performances, environmentally friendly dinner parties and special candlelit evenings for single people, the BBC's Phil Mercer reports from Sydney.
Some pubs are spending the evening without the lights on while many Australians are marking the occasion quietly in the darkness at home.
Some pubs are spending the evening without the lights on while many Australians are marking the occasion quietly in the darkness at home.
Australia is one of the world's worst per capita emitters of greenhouse gases and many believe recent droughts and floods are the result of man's destabilising influence on the climate, our correspondent says.
Australia is one of the world's worst per capita emitters of greenhouse gases and many believe recent droughts and floods are the result of man's destabilising influence on the climate, our correspondent says.
New Prime Minister Kevin Rudd has made the environment one of his priorities, signing up to the Kyoto Protocol on tackling climate change soon after he took office.
New Prime Minister Kevin Rudd has made the environment one of his priorities, signing up to the Kyoto Protocol on tackling climate change soon after he took office.
Will you be switching your lights off? What do you think of this idea? Send us your comments using the form below:
Will you be switching your lights off? What do you think of this idea? Send us your comments using the form below:
