Sydney Blacks Out for Climate Change

Framed between an almost full moon and starlight above, and street lights and glow-worms of traffic below, the icons of Sydney's skyline were silhouettes in the soft darkness.

To draw attention to the simple ways we can fight global warming, Sydneysiders were invited to turn off their lights for an hour, launching a ongoing campaign aimed at reducing the city's greenhouse gas emissions by 5 per cent this year alone.

An initiative of Fairfax Media and World Wildlife Fund Australia, Earth Hour won the support of more than 2000 businesses and government departments, along with some 65,000 households.

At the official launch at Mrs Macquaries Chair, guests watched as 7.30pm ticked over, triggering the man-made blackout.

"It's an hour of active, thoughtful darkness, a celebration of our awakening to climate change action," actor Cate Blanchett said, as candles and torches replaced electric light in hundreds of offices and thousands of homes - in restaurants and hotels, house parties, picnics, on beaches, at a bush dance and even a wedding.