Thousands of residents and businesses in Australia's biggest city, Sydney, have pledged to plunge themselves into darkness in a nod to global warming.
Thousands of residents and businesses in Australia's biggest city, Sydney, have pledged to plunge themselves into darkness in a nod to global warming.
At 1930 (0930 BST) lights will go out in tower blocks, on the iconic Opera House, and in tens of thousands of suburban homes in an orchestrated plan.
At 1930 (0930 GMT) lights will go out in tower blocks, on the iconic Opera House, and in tens of thousands of suburban homes in an orchestrated plan.
The so-called Earth Hour is supported by the New South Wales government, environmental groups and businesses.
The so-called Earth Hour is supported by the New South Wales government, environmental groups and businesses.
Sydney hopes the event will make a very big statement on climate change.
Sydney hopes the event will make a very big statement on climate change.
The city of four million people is aiming to become the first anywhere to achieve a blackout on this scale.
The city of four million people is aiming to become the first anywhere to achieve a blackout on this scale.
The lights will go out on the famous Opera House and Harbour Bridge, along with skyscrapers in the central business district.
The lights will go out on the famous Opera House and Harbour Bridge, along with skyscrapers in the central business district.
Co-operation
Co-operation
An army of home owners is expected to join in too.
An army of home owners is expected to join in too.
Many restaurants have signed up and will serve diners by candlelight.
Many restaurants have signed up and will serve diners by candlelight.
One of the driving forces behind Earth Hour is the WWF environmental organisation. Its chief executive in Australia is Greg Bourne, who says the big switch off has taken months to plan.
One of the driving forces behind Earth Hour is the WWF environmental organisation. Its chief executive in Australia is Greg Bourne, who says the big switch off has taken months to plan.
"The logistics is really quite amazing in the sense every tower block is owned by one company, maybe leased by another company, have 10 tenants in and a manager and working through all of these people has been fantastic.
"The logistics is really quite amazing in the sense every tower block is owned by one company, maybe leased by another company, have 10 tenants in and a manager and working through all of these people has been fantastic.
"But the co-operation has been amazing so we have our fingers crossed that at 1930 at night the lights will go off," he said.
"But the co-operation has been amazing so we have our fingers crossed that at 1930 at night the lights will go off," he said.
Organisers want to encourage Australians to conserve energy and to think carefully about what they can do to cut pollution.
Organisers want to encourage Australians to conserve energy and to think carefully about what they can do to cut pollution.
Every day millions of lights and computers are left on in deserted office blocks as well as in apartments and houses.
Every day millions of lights and computers are left on in deserted office blocks as well as in apartments and houses.
Campaigners have said that simply switching them off could reduce Sydney's greenhouse gas emissions by 5% over the next year.
Campaigners have said that simply switching them off could reduce Sydney's greenhouse gas emissions by 5% over the next year.
Australia is one of the world's largest per capita producers of carbon dioxide and other gases that many scientists believe are helping to warm the earth's atmosphere.
Australia is one of the world's largest per capita producers of carbon dioxide and other gases that many scientists believe are helping to warm the earth's atmosphere.
Are you in Sydney and planning to take part in the event? Send us your comments and photos using the forms below:
Are you in Sydney and planning to take part in the event? Send us your comments and photos using the forms below: