This story is from our news.com.au network Source: AAP The Opera House, Sydney Harbour Brid... Sydney icons switch off for Eart

The Opera House, Sydney Harbour Bridge and Luna Park have all gone dark and many lights in CBD buildings have been turned off, although a number of lights remained on.

About 65,000 households and 2000 businesses committed to joining Earth Hour, which is part of an effort to cut the city's greenhouse gas emissions by five per cent in the next 12 months.

Celebrities and dignitaries including Labor MP Peter Garrett, Sydney Lord Mayor Clover Moore and federal Labor Leader Kevin Rudd attended a function at Mrs Macquaries Chair and watched the city skyline go dark.

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