No more “stop the boats” or “axe the tax”. In announcing his challenge to Tony Abbott on Monday, Malcolm Turnbull promised to take Australian politics away from the mantrafication of policy by three-word chant.

He offered to treat the public intelligently, to engage it with reasoned explanations for policy change, and to fashion a convincing positive economic narrative for Australia.

You could almost hear a collective sigh of relief from the withered body politic.

Turnbull also campaigned for leadership on the basis that he could save the Coalition from an impending crushing electoral defeat. The immediate bounce in polls after the leadership coup suggests that he mobilises extra support based on public expectations that he will lead a government that is more progressive, intelligent and humane on a range of issues – including climate.

Yet almost immediately following his ascension, Turnbull plunged ahead with clumsy pledges to keep Australia’s current emissions target, to preserve Direct Action, and not to introduce a price on carbon.

The price of power

It is widely believed that Turnbull’s latest climate policy comments reflect backroom deals done to secure leadership support from the Liberal Party’s right wing and the government’s coalition partners, the Nationals.

As a result, Turnbull now faces tension about how he balances competing demands from inside and outside government. Is he the party’s leader or its factional hostage? Should he satisfy his colleagues’ demands ahead of those of the public?

He also has to counter enduring suspicion about his autocratic tendencies, generated during his reign as opposition leader. And he cannot underestimate the hostility of the Liberal Party’s deposed neoconservatives for his “small-l liberal” views - climate being a key case in point.

On Monday he took pains to stress that good cabinet processes and wide consultation about policy changes are essential for a level of factional acquiescence, if not actual harmony, within the party.

Simultaneously he has to negotiate public expectations built by his many pronouncements about climate policy during and since his time as environment minister under John Howard in 2007, and then as opposition leader during the debates about carbon trading in 2009.

It would be naïve to think that Turnbull can simply ignore these competing pressures.

Plans and pledges

Turnbull is on record emphasising the reality of global warming and the economic soundness of carbon pricing and emissions trading as the most cost-effective way to curb greenhouse emissions. He has described the Abbott government’s Direct Action policy as “fiscal recklessness on a grand scale”.

If, without explanation, he abandons his previous views in an attempt to satisfy the faceless men of the Liberal Party, he will disappoint a public that has invested him with high hopes for change. Perceptions of insincerity, or of plain weakness, will cost him in the opinion polls, as they did Kevin Rudd before him.

So what can Turnbull reasonably deliver as he attempts to bridge the divide between the demands of the dethroned warriors of Liberal Party’s right and those of his adoring public?

In reality he has more wriggle room than he seems to imagine. His party surely has zero appetite to enter the terminal terrain of ongoing leadership turmoil. We have seen what happens electorally to governments that tear themselves apart.

What’s more, backroom deals to remain conservative on climate change don’t square with the public’s expectations and appetite for stronger, well-justified policies on global warming.

The gap between public opinion about climate action and the Abbott government’s climate policies increased during its two years in office.

Public opinion has now bounced back toward 2009 levels. As the 2015 Lowy Poll suggests, half of Australian adults now agree that global warming is a “serious and pressing problem” and that “we should begin taking steps now even if this involves significant costs”. This is the strongest result on this question since 2009; concern is up 5 percentage points since last year, and 14 points since 2012.

And with the Paris climate summit on the horizon, 63% of respondents said the government should commit to significant emissions reductions so that other countries will be encouraged to do the same.

For Turnbull not to recognise that the views of the climate deniers championed by Abbott are increasingly marginal would be a mistake. It would also be a misjudgement to believe that fresh climate policy can wait until after the next election.

Climate was shaping up to be a major electoral wedge issue because of Abbott’s weak performance. It will remain so unless Turnbull does something new. He will be judged on his government’s climate policy performance during the remainder of this term, not on last-ditch election promises.

Staying true to his predecessor’s climate policies is a gift to Labor and the Greens, for several reasons.

First, his continued support for Australia’s 2030 emissions target, despite the widespread acknowledgement that it is among the weakest from developed countries, leaves him some tricky questions to answer.

He will have to explain why the stronger targets advocated by the Climate Change Authority should be ignored, despite the Authority being explicitly set up to offer independent expert advice.

Second, he would have to justify his newfound support for Abbott’s Direct Action Plan, which he previously criticised as economically inefficient, expensive and weak compared to other emissions-reduction measures.

Third, attacking Labor’s goal of 50% renewable energy by 2030 implies support for Abbott’s approach to renewables. The Coalition’s hostility to the renewables target, and its eventual reduction, drained investor confidence, diminished investment, and cost jobs.

This does not square with the need to revitalise the Australian economy and make it fit for a low-carbon future, or his 2010 statement that we “must move, if we are to effectively combat climate change, to a situation in which all or almost all of our energy comes from zero or very near-zero emissions sources”.

As the contradictions mount, ditching rather than defending weak climate policies seems a much wiser political option for Turnbull, and better for the nation too.