The NSW Premier, Morris Iemma, accused critics of Earth Hour of peddling "utter rubbish" at the launch of the event at Circular Quay this morning.
"The critics and sceptics need to get on board," Mr Iemma told an audience of business supporters of Earth Hour this morning.
"It's utter rubbish to say that symbolism can't lead to change. Yes it's about symbolism but it's a very powerful one - it's about saving the planet."
Some of the world's largest cities would take part in the energy-reducing initiative this year and its adoption worldwide was a vital step in creating "real practical change", Mr Iemma said today.
While cynics may think Earth Hour symbolises a stick — to beat them with — it really is a boomerang.
"What started a year ago in Sydney has become a global movement as more and more cities around the globe join the battle against climate change, and it is a battle in which every one of us can make a difference," Mr Iemma said.
"[When] 2.1 million Sydneysiders just on a year ago switched off the lights, the critics and the sceptics said that it was largely a symbolic gesture.
"I don't agree with that. What the critics and the sceptics fail to understand is that symbolism can be very powerful when it comes to change.
"That's what Earth Hour is about: real practical change."
WWF-Australia, which is organising Earth Hour with the support of Fairfax Media, publisher of the Herald, said that three-quarters of the top 100 companies listed on the Australian Stock Exchange had agreed to take part.
The WWF said that all of the state's major property companies will join in, as well as 70 per cent of the state's one-, two- and three-hat restaurants, the top five banks and 85 per cent of the state's main hotels. The 50 largest local councils in NSW will also take part.
On the Facebook social networking website, 657,658 people have signed up for more than 150 separate Earth Hour events, while, on the Earth Hour website more than 80,000 people had signalled their willingness to take part, with the figures expected to spike as March 29 draws nearer.
Cities taking part in this year's Earth Hour include Atlanta, San Francisco and Chicago in the United States, Denmark's four largest cities, London, Dublin, Tel Aviv, Bangkok and Christchurch.
Most Australian capital cities are participating, as well as Newcastle in NSW.
Global Warning Climate Change Energy