Politics, they say, is the art of the possible. But what they don’t add is that the possible, like beauty, is in the eye of the beholder.

An idea may be rejected as utterly unachievable by one politician only to be embraced as an exciting challenge by another. Thus Professor Ross Garnaut’s conclusion that the best Australia can manage in the fight against climate change is a policy that condemns both the Great Barrier Reef and the Murray-Darling system to extinction was never going to gain universal acceptance.

Garnaut is deeply pessimistic about the future; there is, he says, only a slender chance that humanity can get it all together and none at all that the nations of the world will reach a consensus to cut greenhouse gas emissions enough to avoid catastrophic climate change.

In the circumstances the only practical option for Australia is to pursue a global agreement to stabilise concentrations in the atmosphere at 550 parts per million, an overall increase of about 25 percent on today’s figure. In Australia’s case this would leave Kevin Rudd’s promise of a 60 percent cut in carbon emissions by 2050 intact, but would mean a reduction of only 5 percent, or at most 10 percent, by 2020.

This could be achieved through an initial carbon price of $20 per tonne in 2010, increasing slowly but steadily to about $35 per tonne. Petrol would rise by about 5 cents a litre and electricity bills to consumers by about 40 percent, but compensation would be paid with the money raised through the carbon tax. Overall, economic activity would decrease by just 1 percent by 2020.

So in spite of the predictable screams by the business community, economically it should be affordable. The real cost is to the environment: a likely temperature rise of three degrees Celsius by the end of the century, with (among many others) the aforementioned consequences for Australia.

Garnaut’s target makes a series of assumptions about both the international and Australian communities, the main one being that each is lying. At the Bali conference at which Australia finally committed to the Kyoto protocol, the European Community secured general agreement that the world should aim to stabilise its emissions not at 550ppm, but at 450ppm. This would hold the predicted temperature rise down by about 1 degree, which doesn’t sound much but would be sufficient to avoid the kind of catastrophic climate change we are now facing.

But of course there would be an economic cost: it would require a 25 percent cut in emissions by 2020 and 90 percent by 2050, with carbon prices rising to $60 per tonne. Interestingly, the additional fall in national productivity would be minimal: about a half of one percent.

At the Copenhagen conference the Kyoto countries reaffirmed the target and set the developed countries an aspirational target for emission reductions of 25 to 40 percent by 2020. Of course not all of them expected to meet the target, but at least they were prepared to aim a bit higher than 10 percent. Australia signed up and polling showed that the electorate was generally willing to pay the price.

But the business community most definitely wasn’t and commissioned various doom and gloom reports which claimed to show that such cuts would bankrupt numerous companies and send many others off shore — precisely the kind of threats we used to hear whenever tariff reductions were mooted.

This was bullsh-t then and it’s probably bullsh-t now, but merely putting the argument has enabled business to suggest that what we really have is an either-or argument. Forget the science, ignore the horrendous risks involved: there is a simple choice. We can go along with the wild-eyed greenies and return to the caves or we can support our patriotic industrialists and maintain our standards of living. But whatever happens we mustn’t get ahead of the rest of the world, because if we do we will be at a competitive disadvantage.

This is essentially the Brendan Nelson approach, which is seriously flawed for a number of reasons. For starters it ignores the fact that large slices of the world, particularly Europe, have already got a long way ahead of us in emission reductions, because they didn’t spend the whole of the last decade in a John Howard-like state of denial. The big polluters saw what was coming and have been busily cleaning up their act. In Australia, by contrast, it has been business as usual.

And the do-nothing-yet-and-not-much-ever approach, as favoured by Brendan Nelson, continues the myth that because Australia’s total emissions hardly count in the world context, what we do doesn’t matter. This is simply untrue: we are now the worst per capita polluter on the planet, and gold medal winners tend to be noticed, as was obvious when we finally ratified Kyoto.

And of course, the idea that the industrialised countries like Australia should wait for the developing countries like India to commit to reductions before they lift a finger is preposterous: if the people who made the mess in the first place can’t be bothered to start cleaning it up, why should anyone else? Far from providing an excuse for timidity, Australia’s situation actually makes it ideally placed to take a lead.

Garnaut may be right: it may be too late and too difficult, and we’re all stuffed. But at least we can have a go. If Kevin Rudd truly represents the reforming centre of politics, this is precisely the time to make reform the central issue.