As national elections are nearing in that country, Blanchett called upon Prime Minister John Howard and Labor leader Kevin Rudd to spell out concrete measures to combat climate change.
She visited Monday the drought-ravaged Lake Samsonvale, north of Brisbane, and urged Australians to make global warming an election issue. She was launching a new web-based campaign, whoonearthcares.com.
The campaign, run by the Australian Conservation Foundation (ACF), urges people to visit the website, express their concerns about climate change and take action.
The 38-year-old star said there was no greater issue facing the world, but neither the Howard government nor Labor was doing enough.
"I think both parties need to do more," Blanchett said.
"We need to have legislation in place so that we can basically say that a quarter of our energy needs is met by renewable sources, and we need to have very firm, not soft, emission targets, because by 2050, developed countries need to be working towards the 80-90 per cent cut in greenhouse emissions."
She said Australia must ratify the Kyoto climate change protocol, which Australia and the United States have refused to sign because it excludes high-polluting developing countries like China and India.
"People should write a letter (and) say to their politicians `This is an election issue'."
Blanchett said Australia had "incredible" alternative resources such as sun and wind, but she thought it was lagging behind the rest of the world.
"And it is disappointing when you see the EU's (European Union) commitment to reduce their emission levels by 20 per cent below the 1990 level by 2020," she said.
"So I do think we are lagging behind, which is not in our nature."
Blanchett, who was chauffeured out to the lake in a fuel-efficient hybrid four-wheel-drive, said she had become involved in the campaign because she was concerned for the future of her young sons, Dashiell and Roman.
She also said she "led by example", fitting out the family home in Sydney's leafy Hunters Hill with a water tank, solar panels, grey water and low energy lighting.
"I want to be able to look them in the eye and say that I made these very simple and large changes, and to help them and to educate them and lead them into the future," Blanchett said.
ACF executive director Don Henry hoped the website reached "hundreds of thousands" of Australians.
"We are the privileged generation. We've actually got the opportunity still to make sure our kids don't inherit dangerous climate change," he said.
A message posted on the website today said it was experiencing technical issues due to "overwhelming" traffic.