THE Baillieu government's credibility on climate change has been undermined after economic modelling that it commissioned contradicted its own claims that Victoria would be the state hardest hit by a price on carbon.

The embarrassment was compounded yesterday when Treasurer Kim Wells gave a gaffe-filled media conference, in which he erroneously denied that the state had a legislated goal of cutting greenhouse emissions by 20 per cent this decade.

Treasurer Kim Wells' gaffe-filled press conference has helped to undermine the state government's credibility on climate change. Credit:Arsineh Houspian

And despite describing the target as ''aspirational'', Mr Wells would not say that the government aspired to meet it.

A report by Deloitte Access Economics - commissioned and paid for by the Baillieu government - found Victoria's gross state product would be lower with a carbon price than without one. But it said Victoria would be less affected by 2030 than Western Australia, Queensland, New South Wales and the nation as a whole.