Tony Abbott’s climate “strategy” – repeated sagely in many columns since Tuesday – is to “neutralise” the “environmental” argument with his new 26% greenhouse target and then attack Labor’s policy on economic grounds. This argument is several different kinds of stupid.

First the target can only “neutralise” the environmental argument if voters are silly enough to accept two things. One, that Australia has no obligation to do its fair share of the job of limiting global warming to 2 degrees. (The target is sort of in the ball-park of other developed nations’ targets, but it doesn’t represent a fair share.) And, two, that they take on trust that the Coalition’s “surprise box” of yet-to-be-announced climate policy (see graphic below) is capable of meeting the target, and delivering the environmental benefit. (Using a range of policies is probably quite sensible, but the only announced policy is the emissions reduction fund – all the others are not yet detailed, to the deep consternation of business leaders, who are calling out the policy void.)

Second, the economic “attack” can only succeed if voters are silly enough to accept that the cost of the yet-to-be-announced, and therefore uncosted Coalition policy is smaller than the costs of Labor’s yet-to-be-announced and therefore also uncosted alternative.

Let’s start with the government’s policy. We can’t “cost” it – as in add up the dollars needed for the various parts – because the various parts of the surprise box have not yet been detailed. But the target has been modelled. The government has not yet released the modelling, by leading economist Warwick McKibbin, but Guardian Australia has reported on it. It says the 26% target will shave 0.2% to 0.3% from GDP in 2030.

Then let’s look at the Labor policy. Oh, wait, there isn’t one. There are also no alternative targets. There’s a promise to have some sort of emissions trading scheme and a vague pledge to have 50% renewables. But there’s no detail. All those Bill Shorten press conferences in front of solar arrays and wind turbines have been long on rhetoric and devoid of policy fact. So there are no costings of Labor’s policy either.

Tony Abbott defends 2030 emissions target criticised as 'pathetically' low Read more

This was obviously a problem for Abbott’s big comparative economic costings “attack”. So he made some up. Drawing on a carefully-placed story in the Daily Telegraph, which was based on publicly available modelling done by the Climate Change Authority three years ago, the government alleges Labor’s non-policy will cost $600bn, and cut 2% off GDP growth in 2030. I discuss the origins of this blown-up “scary” number in more detail here.

And even if Labor did decide to back a 40% greenhouse gas reduction target by 2030 – there is much more recent modelling of that. The government’s own modelling! The same modelling that showed a 26% target would shave 0.2% or 0.3% from GDP growth also found, using the same assumptions, that a 35% target would cut 0.3% to 0.5% from GDP and a 45% target would cut 0.5% to 0.7%. That’s a quarter of what the other modelling said. Much less scary. How inconvenient. No matter, Abbott proceeded with the argument that only Labor’s yet-to-be-announced policy will come at a cost to “growth and jobs”, whereas his yet-to-be-announced policy will protect them.

In the real world – rather than the sometimes entirely fictional world of political rhetoric – companies and voters would like to know exactly what policies the major parties are considering, instead of hot air comparing the unknown economic costs of two yet-to-be-announced plans.