Setbacks for advocates of strong action on climate change have come in quick succession in the months since Copenhagen. If the demise of the US climate bill was the most important, the turnaround in Australia -- which boasts some of the highest per-capita emissions of greenhouse gases in the world -- may be the most striking.

Australian Labor fought and won the 2007 election pledging an emissions trading scheme (ETS) by 2010. It will face the people later this month promising to defer a final decision on whether to introduce an ETS to 2012.

This dwindling of political will has raised fundamental questions about the government. Climate change was the totemic issue for the "new leadership" offered by Kevin Rudd in 2007. In addition to his off-the-cuff welcome to Hu Jintao in excellent Mandarin, Rudd's climate activism was crucial to his self-presentation as a modern, forward-thinking leader. Back then, Rudd called climate change "the greatest moral, economic and environmental challenge of our generation". He condemned the inaction and climate scepticism of his predecessor, the conservative John Howard.

Labor's advertising campaign even depicted Howard asleep in his bed, famously bushy eyebrows visible above the duvet, with a framed photo with George W Bush on the bedside table. While an alarm clock blared away in vain, the voice-over pronounced Howard "asleep on climate change".

But the "greatest moral challenge" does not feature in Labor's ad campaign this time around.

Labor's ETS was rejected by parliament in December after a last-minute rebellion of opposition conservatives -- one of whom branded climate change a conspiracy of "the extreme left" to "deindustrialise the western world". But instead of fighting another election on the issue, Rudd announced in April that the ETS would be delayed until at least 2013.

His credibility never recovered. Political opponents who had accused the government of having a hollow core claimed vindication. Ross Gittins, a prominent economic commentator, labelled Rudd "a weak man fallen among thieves". His standing deemed unsalvageable by party hardheads, Rudd was replaced as leader in June by his deputy, Julia Gillard.

Gillard soon called an election and announced that a returned Labor government would review plans for an ETS in 2012, after establishing a randomly selected "Citizens' Assembly" to "examine" climate change and "test" community consensus. But consensus on contentious issues is by definition a chimera. Each of the major economic reforms in Australia over the past 30 years was carried out in the distinct absence of community consensus.

The announcement drew widespread derision. Labor's lead has evaporated in most polls. The attempt to kick the ETS into touch simply exacerbated the doubts raised by Rudd's backflip.

This should not be a surprise. A recent poll found that 60 per cent of Australians want an ETS. The global financial crisis is often cited as a reason for weakening demand for action on climate, but Australia did not have a recession. What's more, many people were persuaded in 2007 of the urgent need to put a price on carbon. They find it difficult to accept that this need has become less urgent, not more, in 2010.

Australia's three-year electoral cycle makes U-turns decidedly risky. People may not have long memories, but they certainly have short ones.

Few doubt that Rudd would have won an election immediately after the parliament rejected his ETS. Eight months later, his successor is locked in a tight race with an opposition leader who once declared climate-change science to be "absolute crap". Labor did not learn the obvious lesson. It was Rudd's capitulation on climate, not his original boldness, that shattered his credibility and his standing in the polls.

Gillard's campaign has borrowed the "Forward not back" mantra from New Labour. On climate, she might have been better off paying heed to another of Tony Blair's tenets: "At our best when at our boldest."

Stephen Minas covered the Copenhagen climate summit for Radio Television Hong Kong and the Diplomat magazine and recently completed a Master's in international relations at the London School of Economics.Twitter: @StephenMinas