To deploy an Americanism, climate change has become the third rail of Australian politics: treacherous, untouchable and normally lethal. Over the past five years, no leader on either side has come up with an environmental policy that is politically sustainable. Quite the opposite is true. Climate change has contributed already to the downfall of three Liberal leaders and a Labor Prime Minister. Julia Gillard is but the latest politician struggling to plot a course through the mists of the country's billowing emissions.
Green politics contributed to the downfall of John Howard. His refusal to ratify the Kyoto Protocol ahead of the 2007 election became emblematic, and was woven into the narrative of an elderly leader who was out of touch, too set in his ways and too closely aligned with the Bush administration.
For Howard's successor, Brendan Nelson, climate change also reinforced the central criticism of his leadership, that he was prone to vacillation. Trying to straddle a divided party, Nelson first adopted a skeptical line on the emissions trading scheme, only to reverse himself under pressure from Malcolm Turnbull. From that moment on, he was destined to spend more time with his family.
Turnbull was convinced of the science and impressed by the example of David Cameron in Britain, for whom environmentalism became totemic in his rebranding of the Conservatives. Ahead of the Copenhagen climate change conference in 2009, he therefore offered bipartisan support for the Rudd's government's emissions trading scheme. Yet he might have learnt another lesson from the British conservatives, which was the danger posed from mutinous skeptics. At Westminster, it was euro-sceptics. In Canberra, it was enviro-sceptics. Soon they ousted him as leader.
For Tony Abbott, scepticism first helped win him the Liberal leadership. Then it helped propel him, unexpectedly, in the polls as he successfully harnessed the mood of growing public skepticism in the months after Copenhagen. Still, it only got him so far. Labor seized upon Abbott's "absolute crap" line, thus reinforcing his plausibility problem with large swathes of the electorate.
On the Labor side, Kevin Rudd's difficulties on the issue are well-documented, not least because the former Prime Minister has helped document them so publicly himself. Again, it was what the retreat on the ETS came to signify, as much as the policy change itself, that was defining. By retreating from his signature issue without much of a fight, Rudd had failed the great Australian ticker test.
Like Rudd, Julia Gillard has been savaged by her own sound-bite: for "greatest moral, economic and social challenge of our time" read "no carbon tax under a government I lead". Caught in the clutch of circumstance, with the Greens and independents insistent upon action, she has been forced to champion a policy that is ostensibly the same as the one she argued against in cabinet this time last year.
What they have all shared in common is a difficulty in reading the public mood on this vexed question, which is entirely understandable. After all, the shift in Australian public opinion, from the green-friendly salad days of An Inconvenient Truth, the Stern Report, and the studies of the UN's Intergovernmental Panel on Climate Change, has been extraordinary. Here, the great public relations coup of the growing band of opponents to the carbon tax has been to shift this from a debate about the environment to a debate about the economy.
To borrow two unlovely phrases from the world of economics, first they pitched the argument at the macro-level: a carbon tax would threaten Australia's prosperity by penalizing the very sectors that make it rich. Now, even more powerfully, they have prosecuted the case at the micro-level: at a time of rising fuel prices and energy bills, a carbon tax would stretch household incomes to breaking point.
There is another conspicuous paradox. Though the Australian environmental movement has been pushed back onto the defensive since Copenhagen, its political wing, the Australian Greens, is about to gain more parliamentary power than ever before. For Julia Gillard, who has already been accused of being Bob Brown's poodle and of being dragged too far to the left, this will make the politics even more diabolical because she has so little room for maneuver.
Given the experience of John Howard, Kevin Rudd, Brendan Nelson and Malcolm Turnbull, it would be tempting to argue that whichever Australian politician manages to engineer a policy that is both environmentally sound, economically viable and politically palatable could dominate Canberra for years to come. Yet here we are dealing with an altogether different kind of journalistic trope. Not a third rail, but a holy grail.
PS I am now tweeting merrily away - if that is the correct terminology - at @NickBryantBBC.