The Labor government has heralded the dawn of a "new era of climate and energy policy certainty" after a bill to enshrine its 43 per cent 2030 emissions reduction target in law passed Parliament's lower house.
But after agreeing to support the bill, the Greens are now threatening a blow up a key part of Labor's agenda as part of their fight to stop new coal and gas projects.
Teal independents are also set to pressure Labor to raise its emissions targets and phase out fossil fuels, after praising the government's "collaborative" approach to negotiations on the climate change bill.
Amid the calls for the government to ban new coal and gas projects, Environment Minister Tanya Plibersek has flagged she intends to block a coalmine project backed by mining billionaire Clive Palmer in central Queensland, due to likely "unacceptable impacts" to the world heritage-listed Great Barrier Reef.
The Albanese government's landmark bill passed the lower house on Thursday with the support of the Greens and independents, who managed to secure last-minute changes to strengthen the legislation.
Liberal backbencher Bridget Archer crossed the floor to vote with Labor, after the Coalition elected to oppose legislation it said was "unnecessary".
Prime Minister Anthony Albanese lashed the Coalition's stance, accusing it of "not acting like they have the best interests of Australians to heart".
The bill will now be sent to the Senate, where it looks set to pass after Greens leader Adam Bandt this week confirmed the party wouldn't use its 12 votes to sink Labor's plan.
The government still needs the support of one more upper house crossbencher.
ACT independent David Pocock was on Thursday again expressing support for Labor's plan, but said he wouldn't be acting in the best interests of Canberrans if he simply rubber-stamped the bill before it reached the upper house.
Senator Pocock signalled he would use negotiations to push for stronger requirements around reporting on progress against the climate targets, which he described as "small" and "sensible" changes.
Labor's bill would also legislate its net zero by 2050 target, task the Climate Change Authority with providing advice on future goals and require the minister to make an annual progress statement in Parliament.
The government agreed to raft of minor amendments from crossbenchers during debate on Thursday morning, including further clarifying that its 43 per cent emissions reduction target was not a ceiling to its ambitions.
Warringah MP Zali Steggall won support for a change which would require the government to seek advice from the Climate Change Authority before submitting new emissions reduction targets to the United Nations - including for 2035, 2040 and 2045.
The authority would also be required to provide advice on the benefits of new emissions reduction targets for rural and regional Australia, after the government supported the suggestion from Indi MP Helen Haines.
"The passing of this bill in the House of Representatives starts a new era of climate and energy certainty, one that is well overdue," Climate Change and Energy Minister Chris Bowen said.
Mr Bandt, who tried unsuccessfully during the debate to raise Labor's 2030 emissions reduction target to 75 per cent, said the bill was a "small step on the road to tackling climate change".
He argued the Greens had "won round one" after securing changes to the bill, but vowed the fight to prevent the opening of new fossil fuel projects would now ramp up.
In his most serious threat yet, Mr Bandt said the Greens were prepared to use their numbers in the Senate to torpedo Labor's planned reforms to the so-called safeguards mechanism - the scheme used to limit emissions at heavy polluting sites.
Mr Bowen was this week adamant that the government would implement the plan it took to the May federal election, which involves lowering the emissions thresholds at the 215 sites covered under the scheme to help them reach their own net zero by 2050 goals.
Mr Bandt said he wanted to use the mechanism to stop the opening of new fossil fuel projects.
"We will be pushing very strongly in our discussions with the government to say the safeguard mechanism needs to safeguard our future by stopping the opening of new coal and gas projects," he said.
But Ms Plibersek has on Thursday moved on a proposed coal project, rejecting in a draft decision the Clive Palmer-backed Central Queensland Coal Project, just 10km from the edge of the Great Barrier Reef Marine Park.
It is her first decision as environment minister and the first ever refusal of a coal mine by a minister under the Environment Protection and Biodiversity Conservation (EPBC) Act 1999.
Environmental groups, including Lock the Gate, have welcomed the "common sense" rejection of the destructive, polluting and "crazy" proposal.
"Based on the information available to me at this stage, I believe that the project would be likely to have unacceptable impacts to the Great Barrier Reef Marine Park, and the values of the Great Barrier Reef World Heritage Area and National Heritage Place," the minister said in a statement.
"The available evidence also suggests that the project would be likely to have unacceptable impacts on water resources in the area."
The draft decision now goes to public comment, including Mr Palmer's company, with submissions closing on August 18 before a final decision is made.
A Senate committee inquiry into Labor's climate bill is due to report on August 31.