The release of the Garnaut report tomorrow provides the Rudd Government with an opportunity to stop campaigning and start governing.

The auguries are mixed. For two weeks Prime Minister Rudd allowed himself to be sucked in to the vortex of petrol price populism, until he and his fellow ministers began to fight back against the unscrupulousness of the Opposition.

Rudd began testing his lines in Parliament, working out how to persuade the public to return to thinking about the future.

It worked, putting Nelson and Turnbull on the back foot. They were forced to reaffirm that they are not climate sceptics and accept the science of global warming. That this had to happen only proves how antediluvian the climate debate is in this country compared to, say, Britain where the Tory leader David Cameron has positioned the conservatives as greener than Labour.

Even for the cynics amongst us, the willingness of Nelson and Turnbull to undermine the shaky political consensus on the greatest threat to the welfare of future Australians in exchange for a small and very short-term political gain is breathtaking.

The best news we have had for a while came in the form of this week’s Newspoll results. The results showed strong public support for an ETS — 61% for and 25% against.

Perhaps we should not be so surprised — both parties promised an ETS and Australians voted for it. Perhaps the petrol price panic is only skin-deep, a bit like an anxiety attack that soon passes.

Kevin Rudd may be right that the Opposition has been lying about accepting climate science and the ghost of Howard still rules the party room, not to mention the Opposition leader’s office. After all, Nelson appointed one of Australia’s foremost climate denialists as his international adviser. As opinion editor of The Australian, Tom Switzer was always eager to give space to the latest denialist pseudoscience or ideological warriors who equate action on climate change with capitulation to green extremism.

But over the next few days there is much more at stake than petrol price parochialism and ute men complaining about the price of girlie drinks in Gippsland.

Last December, when Kevin Rudd went to the Bali climate conference to receive the ovation of his life, he chose the boldest words to underline his and Australia’s commitment to responding to global warming.

“Australia now stands ready to assume its responsibility,” he declared.

“Climate change is the defining challenge of our generation … one of the greatest moral, economic and environmental challenges of our age.”

In the most decisive break from the approach of the previous government, he promised the assembled delegates that his government is “prepared to take on the challenge, to do the hard work now and to deliver a sustainable future”.

It is a long fall from such a high peak. This week he stands on the precipice, looking into the abyss. It is the greatest test of his political courage. But it won’t be the last on climate. The test this week is the comprehensiveness of the ETS. The next, and bigger, test will occur late this year or next when the Government must decide on the level of the cap on emissions. There is an expectation that the target for 2020 will be a 25-40% cut. Unless energy producers and consumers begin changing their behaviour very soon, an emissions limit in that range will mean very large price rises.

It’s worth pointing out, given the widespread misunderstanding, that the Government will not be setting a carbon price. It will set a quantitative limit on emissions (the cap) that will become tighter over time. The limited number of permits will make them valuable to the extent demand for them exceeds their availability. The price of polluting forms of energy will rise according to how much those required to own permits are willing to pay for them.

Few Australians are aware of just how closely the rest of the world has watched the greenhouse debate in Australia. Kevin Rudd was received with such acclaim in Bali because the thousands of delegates knew in all its brutal detail how the Howard Government had spent years attempting to sabotage global efforts to reach an effective agreement.

The cheering of the Bali delegates marked the end of that era. Kevin Rudd now has to deliver on his promises.