The government's climate bill is at risk of being undone before it's even legislated due to coal and gas projects being approved, according to the Greens.
As legislation enshrining a 43 per cent reduction in emissions by 2030 looks set to pass the Senate, the Greens have introduced a climate trigger to fix the country's "broken" environmental laws.
The proposal would ban the environmental approval of new fossil fuel developments that would emit more than 100,000 tonnes of carbon.
It also sets a threshold to require environmental assessments of projects that would emit between 25,000 and 100,000 tonnes of carbon in a year.
Greens leader Adam Bandt said while the party would support the government's emissions bill through parliament, more was needed to be done, such as its climate trigger legislation.
"Does the bill as it stands do enough to tackle the climate crisis? No, it doesn't," he told reporters in Canberra on Monday.
"The government is still hell bent on opening new coal and gas projects and undoing the work of the bill before its even passed."
The proposed climate trigger bill would stop the 114 new coal and gas projects in the pipeline from being built, Mr Bandt said.
Current laws allow the environment minister to approve a new mine or development without considering the impact of the pollution on climate change.
Mr Bandt said there was a "woeful gap" in Australia's environmental laws that needed addressing.
"I wasn't the first person in the House of Representatives history to introduce a bill to put a climate trigger into our broken environment laws. The first person to do that was Anthony Albanese," he said.
"Since that time, Australia has put billions of tonnes of climate pollution into the atmosphere and turbocharged the climate crisis."
Infrastructure Minister Catherine King told parliament she had instructed her department to set up a "net zero unit", with a view to working out how carbon base cases could be determined for major projects.
The idea of a "carbon base case" has been advocated by some groups and crossbenchers including independent Kylea Tink to be used alongside traditional metrics, meaning projects would need to deliver on time, quality, cost and carbon settings.
The government's emissions bill is set to be debated in the Senate this week, but would need support of all 12 Greens senators and one crossbencher to become law.
Negotiations are continuing between the government and crossbench senators, with ACT independent David Pocock describing the talks as "lukewarm".
"We'll continue to have those chats right up till the vote," he said.
"We're both wanting to be constructive ... our proposed amendment is really common sense and sensible and actually strengthens the bill."