WHEN the thousands of Australian households and businesses turn their lights back on after Earth Hour ends tonight, only 10 per cent of them will be switching on any green power.

The difference between one hour of candle-lit symbolism and genuine household action is vast.
Event organisers claimed 54 per cent of Sydney residents took part in the inaugural Earth Hour last year, but surveys show that only 8 per cent of households actually signed up to green power schemes, citing cost and time constraints.
Tonight, the candles will be brought out again and the street lights will be on, only this time across Australia and 24 cities around the world as Earth Hour II goes global. The idea of Earth Hour is for individuals and businesses to "send a message" about their concern over climate change by turning off lights and other electrical appliances from 8pm to 9pm this evening.
Sitting in the dark may appeal to some, but the hard numbers on its impact and emissions saved are less convincing. Measuring real energy cuts over one hour is almost impossible, and so last year it was limited to the Sydney CBD where the "wow" moment was the darkening of lights on the Harbour Bridge and some office-tower signs.
Beyond the symbolic, real change is less tangible.
NSW has the second-lowest take-up rate of green energy in the country. Signing up to green energy is a more robust measurement of genuine household action to reduce greenhouse emissions.
A survey of NSW households by energy retailers conducted just after Earth Hour last March found that 89 per cent of respondents were concerned about the threat of climate change, and 79per cent were aware that they could buy green power, which included at least 10 per cent of their electricity from clean energy sources.
However, only 8 per cent actually signed up to green power schemes, citing cost and time constraints, even though most of the 700,000 participating households in Australia are signed up to entry-level schemes that carry no extra cost.
The big adopters are Victorians, with nearly 15 per cent of households signed up to green power, followed by South Australians on 12 per cent, although all Tasmanians, by default, use some green energy from their hydro dams.
Energy retailers chief executive Cameron O'Reilly said that despite widespread concern about the threat of climate change, household energy use was still principally driven by price.
He said while events such as Earth Hour might help raise awareness, Australians were not being warned of the real and significant cost impacts of cutting greenhouse emissions.
"Earth Hour is useful in awareness-raising, so long as it isn't too fashionable," he said. "But there is no one preparing the public for the real pain associated with climate change."
Energy Australia confirmed street lights in Sydney would again stay on during Earth Hour for safety and security reasons.
While Australian voters sent a message on climate change at last year's federal election, WWF chief executive Greg Bourne said it was still important to reinforce such messages.

"All governments need to know that their voters are behind them in what they are trying to do," he said.
"This is a message going right around the world that Australians care, Americans care, Chinese care, very powerfully signalling that we want our leaders to get on board."
Mr Bourne said while Earth Hour was symbolic, it gave individuals the chance to act, even in a small way, on climate change.
Major energy users said that for them "every hour was Earth Hour", claiming they had been working for years to find ways to cut energy use.
Energy Users Association chief executive Roman Domanski said he found Earth Hour "largely symbolic, but symbolism is sometimes important".