So let's start with the science, before the politics.

This week, over 118 Australian scientists and experts signed an open letter calling on the federal government to listen to the scientific evidence on climate change and to prevent new fossil fuel projects and expansions. The United Nations, the International Energy Agency and the world's scientists are clear: to avoid dangerous climate change we cannot keep expanding fossil fuels.

As signatory and former Australian of the Year, Professor Fiona Stanley AC, summed up on ABC TV this week: "To actually approve new coal and gas, fossil fuel industries now, is like writing a death certificate for the planet."

The government's safeguard mechanism is supposed to reduce emissions from the country's biggest industrial polluters, but it does nothing to prevent new polluters from setting up shop. While the 200 or so individual polluters covered by the mechanism will be required to reduce their emissions (or buy dubious carbon offsets), there is nothing to stop new coal mines and gas projects from going ahead. Every new fossil fuel project will contribute to the problem this legislation is supposed to solve. In other words, Labor is trying to legislate the world's first 'cap and trade scheme' with no actual cap on emissions.

There are more than 100 gas and coal projects in the pipeline awaiting development and they are not hypothetical and neither are their emissions. Just a week ago, Environment Minister Tanya Plibersek quietly approved a Santos fracking project in Queensland's Surat Basin that allows 116 coal-seam-gas wells to operate until 2077. How much of the Great Barrier Reef will remain unbleached by then?

Independent ACT senator David Pocock has raised concerns about the integrity of Australia's carbon credits. Pocock has pointed out Australia is set to join Kazakhstan as the only other scheme in the world to allow polluters to rely 100 per cent on carbon offsets to meet their emission reduction obligations. He's concerned the government has not yet implemented the recommendations to address flaws identified with offsets by the Chubb Review, yet is proceeding with legislation that relies heavily on offsets to achieve its aims.

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"For me, integrity has to be at the heart of this policy. We have to be certain that this will drive the sorts of changes that we desperately need," he said.

Some of the free political advice being handed out to the crossbench is not only scientifically flawed, it's also politically dubious.

The safeguard mechanism is hardly gold-standard legislation that deserves to pass with just a few tweaks. It contains serious flaws and loopholes that could see emissions rise. And those warning Labor to keep its election promises on superannuation are quick to urge the Greens and the Senate crossbench to to break theirs on climate.

The fact is the Greens ran on a platform of no new gas or coal mines and voters delivered them a 'Greenslide' to the Parliament. After the election, leader Adam Bandt flagged the Greens' intentions to Labor: "We will fight in parliament to stop new coal and gas projects, that's what people sent us there for and that's what we will do."

The backlash to the Greens breaking an election promise would be no less serious than the Labor or Liberal party breaking theirs. Few in the Greens have forgotten the political consequences for the Democrats when the then-third largest party passed the GST after securing a range of concessions. The Democrats are now history. For Greens voters climate change is no trivial matter: for most of their base, climate is the number one concern.

There's a lot of earnest warnings the Greens should take care to 'avoid another CPRS, and a weird collective amnesia about the carbon price that was subsequently successfully passed with then-prime minister Julia Gillard. The Clean Energy Future Package worked: the economy grew and emissions went down in real terms for the first time. It also gave birth to two critical bodies: the Clean Energy Finance Corporation (CEFC) and the Australian Renewable Energy Authority (ARENA).

It's worth remembering the Greens received a fundamentally different electoral lesson from the CPRS than Labor. While Labor's vote tanked after Rudd dumped the CPRS (rather than taking it to a double-dissolution election), the Greens vote went up after they blocked the CPRS in the Senate, electing Bandt himself and delivering the best electoral result prior to the 2022 "Greenslide".

Breaking a political promise is no trivial matter, but neither is it an ironclad catastrophe. Just as Scott Morrison was absolutely correct to abandon the Liberals' promise to deliver a budget surplus when the pandemic hit, a majority of Australians (61 per cent) think adapting economic policy to suit the changing circumstances is more important than breaking an election promise.

Rather than litigating the partisan politics of the past, parliament should deal with the reality of the present: a climate crisis and a climate supermajority on the crossbench.

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Curiously, the concerns raised by the pro-climate crossbench about strengthening the safeguard mechanism have been variously described as 'sabotage' or attempts to 'gut' the legislation. Now Climate & Energy Minister Chris Bowen has flagged he plans to bypass the Senate debate by issuing the scheme's final rules via regulation rather than legislation, which the Senate cannot amend, only disallow. Take it or leave it.

Promises notwithstanding, there is a genuine debate to be had about the substance of the safeguard mechanism and the minister should let the Senate have it.

After all, the science couldn't be clearer: fracking until 2077 is neither perfect nor good. It's downright dangerous.