Australia has ratified its acceptance of the Kyoto Protocol on climate change. The new government elected last year made signing the emissions-limiting accord its first act. From Sydney, Phil Mercer reports.

The Kyoto Protocol on reducing greenhouse gas emissions formally went into effect Tuesday in Australia. Environmentalists and other activists had long pushed the Canberra government to ratify the accord, which they say could help protect the continent from the effects of global warming.

Iconic national natural treasures such as the Great Barrier Reef are considered vulnerable to warming temperatures. The government of former Prime Minister John Howard did not signed the accord because of concerns that it would harm the economy and because it does not require large developing nations with rapidly expanding economies, such as China and India, to cut emissions.

The government of Prime Minister Kevin Rudd reversed that policy when it took office in November and is working internationally to develop a framework to replace Kyoto when it expires in 2012. Mr. Rudd wants to establish a domestic carbon emissions trading system and wants 20 percent of Australia's energy to come from renewable sources by 2020.

Mr. Rudd told parliament Tuesday that "confronting climate change is the challenge of our generation."

Senator Bob Brown from the Greens party says Australians are demanding tough action to protect the environment.

"The opinion polls [are] showing massive support for not just the Kyoto Protocol but for much greater measures to tackle climate change," he said. "It's a milestone that we've joined the community of nations and hopefully we'll move back to the front again in searching for a global compact which is going to address the biggest single human-made threat facing our global community into the future, and that's climate change."

Experts say Australia has a long way to go to bolster its green credentials. The country's reliance on cheap coal has made it one of the world's worst greenhouse gas polluters per capita.

Many scientists think greenhouse gases produced by burning coal, oil and other carbon fuels, have contributed to warming temperatures around the globe. Environmental groups have called on Australia to go beyond its target of reducing greenhouse gas emissions by 60 percent from 2000 levels before 2050.

Australia's ratification of the Kyoto Protocol leaves the United States as the only major developed country that has refused to sign the global accord.