ACT Greens climate change minister Shane Rattenbury made the comment in the wake of the federal Cabinet's and Coalition party room approving the official position on Tuesday.

The change in federal policy comes in the face of the Commonwealth's own Chief Scientist Alan Finkel recommending the government mandate a low emissions target, the only recommendation the government has ignored.

However, the federal government has argued its new proposal, which includes requiring energy retailers to meet greenhouse gas emissions standards, may help drive power prices down.

Mr Rattenbury said the switch was clear evidence that the "federal government has succumbed to the climate deniers on the backbench" in a move that would reinforce the role of coal and gas "at a time when we need to be transitioning to renewable energy".

"Every other country in the world is not putting requirements on coal and gas, they're putting requirements on renewables and our federal govt is going in completely the opposite direction," he said.

"It's devastating to see the clean energy target dropped; the Finkel report identified 50 recommendations, the federal government adopted 49 and left the most substantive one behind.

"All the other recommendations are important but this is the core of transitioning Australia more quickly, more efficiently to the renewable energy future we need."

Mr Rattenbury also rejected "flawed arguments" that cheaper energy prices would result, saying that the ACT's 20-year renewable contracts allowed for certainty and predictability.

"If you invest carefully, use good energy targets and put battery storage in place to deal with those peaks then you can have a very cost effective renewable energy system," he said.