Mr Bandt has also said his party wants a discussion with the Albanese government about Labor support for opening new gas and coal projects, but stopped short of saying the Greens would bring demands on the issue to talks about the proposed climate bill to slash emissions by 43 per cent.

The Greens leader, speaking on ABC's Insiders on Sunday, warned Labor against taking a "my way or the highway" approach to a legislated emissions target, saying it would be a long three-year parliamentary term if the government was not willing to be flexible.

Since the government briefed the Greens and other crossbenchers about the draft legislation last week, Mr Bandt has been critical of the bill, which he says sets a ceiling for emissions reductions and fails to create a floor protecting targets from future governments less committed to climate action, such as one led by Liberal leader Peter Dutton.

"If you're going to legislate, you want to Dutton-proof it," Mr Bandt said.

Mr Bandt warned that a new Senate could also oppose increases to the legislated 43 per cent target if the government decided to lift its ambitions.

He said the problem in the bill was "fixable" and that the Greens would enter discussions about the legislation without preconditions.

"It doesn't contain any provisions that will stop coal and gas and also it's in many respects, as some commentators have said, it doesn't actually compel the government to do anything.

"So there's nothing in there that says this is how we're going to cut pollution."

Mr Bandt said the government's position towards new coal and gas projects was a critical factor in the Greens' stance on the proposed bill, and that the party was concerned Labor could add to Australia's emissions after the legislation was passed by opening gas projects in Western Australia and the Northern Territory.

Asked whether he was willing to join the Coalition in opposing the legislation, the Greens leader said: "My hope is it doesn't come to that because the government is able to sit with us and we come up with better legislation.

"Our strongly preferred approach is to improve and pass [the legislation], but if the government says it's our way or the highway, then we're going to have to respond to that."

Labor needs support from the Greens and at least one other crossbencher if, as expected, the Coalition opposes it.

Prime Minister Anthony Albanese last week challenged the Greens to back his bill, effectively blaming them for causing a decade of inaction on climate change through the party's decision to oppose Kevin Rudd's emissions trading scheme in 2009.

Mr Bandt and a number of crossbenchers were on Thursday briefed on the bill, which the government plans to introduce in the first sitting of the new federal Parliament later this month.

The bill would seek to legislate Labor's targets of cutting emissions 43 per cent by 2030 and reaching net zero by 2050. The Climate Change Authority would also be tasked with assessing progress and providing advice on future goals, including a 2035 target.

The Greens and independents are pushing for higher targets ranging from a 50 to 75 per cent cut in emissions by 2030.

Climate Change and Energy Minister Chris Bowen reiterated the government was open to "sensible" suggestions from crossbenchers.

"We have also made it crystal clear we will not be walking away from that mandate," Mr Bowen said.

"We look forward to further discussions with the crossbench on that basis."

Labor's proposed legislation would only enshrine a carbon emissions target and require the government to make an annual progress report to Parliament. If it's defeated, the government could still cut emissions by setting tougher emissions standards, increasing renewable energy projects and capping industrial pollution.