The cost to the economy of adopting a more ambitious emissions reduction target for 2030 is significantly less than claimed by Prime Minister Tony Abbott, the government's own commissioned economic modelling reveals.

The Abbott government released two modelling reports late on Friday afternoon that helped underpin its choice of an emissions cut of 26 to 28 per cent cut from 2005 levels by 2030 as the target it will take to a major climate conference in Paris later this year.

Prime Minister Tony Abbott has announced his government's plans for emission reductions post 2020. Credit:Andrew Meares

In a joint press conference on August 11 to announce the targets, Mr Abbott quoted the modelling to say the target chosen by the government would result in lower gross domestic product of 0.2 and 0.3 per cent from what it would have otherwise would have been in 2030.

But at the same press conference Mr Abbott went on to say: "The modelling that we have done suggests that achieving a 40 per cent reduction by then [2030] will be much more expensive. It will be over 2 per cent of GDP, so that's in the order of $40 billion."