Alberta Environment Minister Shannon Phillips says comments by Wildrose critic Don MacIntyre suggesting the science isn't settled on climate change shows why the party hasn't put forward a credible plan to reduce carbon emissions.

"They are continuing to double down on statements which are not factual, that are not based in evidence and that border into conspiracy theories," Phillips said Tuesday. "And I think Albertans deserve better from their opposition."

On Monday, MacIntyre, the Wildrose critic for renewables and electricity, said the science isn't settled on climate change.

"Climate change is real … it is cyclical, man is aggravating it. Man is not the sole cause, " MacIntyre said.

When a journalist challenged MacIntryre by noting the majority of scientists say humans are the main cause, MacIntyre replied, "You can't say that anymore … the science isn't settled."

The tax, which adds 4.5 cents to the cost of a litre of gasoline, came into effect Jan. 1.

The Wildrose has opposed the measure saying it makes gasoline, diesel and home heating fuels more expensive during an economic downturn.

Phillips said MacIntyre's remarks, which followed her news conference at the Alberta legislature, did not surprise her.

"Because we have seen these kinds of comments from the Wildrose since Day 1. They have not changed at all," she said.

"And despite the fact that the science is settled, the evidence is real, it is overwhelming, and they continue to trade in falsehoods and conspiracy theories. Albertans deserve better and and I believe they should have better from their opposition."

The NDP caucus is calling on Wildrose leader Brian Jean to replace MacIntyre as the party's critic for electricity and renewables.

"Time and time again, Mr. MacIntyre has made comments that are drawn from climate change-denying conspiracy theorists," NDP MLA Shaye Anderson said in a news release. "Unless Mr. Jean agrees with what Mr. MacIntyre is saying, he must remove him from his position."