Key greenhouse gas emitter Australia on Friday said it will sign up for a second round of the Kyoto Protocol environmental protection treaty, but New Zealand opted out.
Climate Minister Greg Combet made the announcement in a speech to a carbon expo, saying: "Australia is ready to join a second commitment period of the Kyoto Protocol."
So far, only the European Union and several smaller economies have signalled a willingness to agree to a second round of pledges.
Australia is among the world's worst per capita polluters, with a heavy reliance on coal mining and exports and most of its electricity coming from coal-fired power stations.
Although Kyoto—the first global treaty to set binding obligations on wealthy countries to cut emissions—was negotiated in 1997, Australia refused to join for years.
It was only when Labor came to power in 2007 that it shifted course.
Combet's announcement comes ahead of annual negotiations under the UN Framework Convention on Climate Change (UNFCCC), which this year take place in Doha, Qatar, from November 26-December 7.
The big issue is renewing commitments under Kyoto after the first round of cuts expires on December 31, although agreement on a new globally-binding deal is not expected until 2015 and will not come into force until 2020.
Combet said Australia's decision was not a blank cheque and other countries must also step up.
"For Australia, there must be continued progress towards this new agreement by 2015, from both the developing and developed countries alike," he said.
"The Kyoto Protocol is not enough on its own—it will cover less than 15 percent of global greenhouse gas emissions and only from a number of developed economies.
"So to be effective, the new 2015 agreement needs to cover all the major emissions sources."
He added: "From 2020 we expect all countries—including the United States, the European Union, China, Japan, India, Indonesia and South Korea—will be part of a new agreement to reduce emissions.
"This will bring all countries onto the same legal platform to reduce emissions."
But New Zealand said it was not signing up, with Climate Change Minister Tim Groser opting to instead manage emissions under the UNFCCC, which does not include binding commitments.
Kyoto is a talisman for developing countries, but more and more developed nations say it is unfair because its binding emissions targets do not affect emerging giants such as China, India and Brazil.
In a statement, British Secretary of State for Climate Change Edward Davey said he hoped the Australian announcement would spur on other countries.
"Having Australia on board will really help to push the second Kyoto protocol period... as we make the transition to a new, global, legally binding deal," Davey said.
Combet said Australia signing was conditional on access to the Kyoto market mechanisms, such as the Clean Development Mechanism, from January 1, 2013.
This would ensure Australian businesses have access to international credits, helping reduce emissions at the lowest cost to the economy.
Canberra also wants existing land sector rules to continue, providing opportunities to cut emissions through better land management.
Once this was agreed, Canberra would take on an emissions reduction target of a five percent cut below 2000 levels by 2020.
"As we've made clear before, the government leaves on the table the potential to increase the target to up to 15 or 25 percent, depending on the scale of global action," Combet said.
Explore further: Regulators order pipeline testing, other steps after spill