Prime Minister Stephen Harper still doesn't believe in the science of climate change, says Liberal Leader Stephane Dion.

Dion, speaking to reporters in Nova Scotia, says the Conservative government's recent embrace of environmental issues must be viewed skeptically.

"He spoke about the 'so-called greenhouse gas emissions'" only weeks ago, Dion said.

The fiscal update of Nov. 25 contained "not a word" about climate change, he said.

"Now all of a sudden, it's a priority. I think something happened ... (Harper) saw the polls, he saw the kind of official opposition he's facing, and he pretended that he saw the light."

For that reason, last week's cabinet shuffle can't be taken very seriously, he said.

Harper replaced Environment Minister Rona Ambrose with Treasury Board President John Baird. He is considered a more aggressive communicator who can stickhandle contentious legislation.

"The science is very strong and I accept it, and I think we've got to take measures," Baird said in an interview Sunday on CTV's Question Period.

In separate Question Period interview, Harper said: "I've said for a long time I think the preponderance of the evidence on this is clear, that it's a real long-term challenge, but what I've said is it can't be fixed overnight.

"This country is headed to be 50 percent over its Kyoto target in 2012. We can't tell the Canadian population to heat their home one-third less of the time."

In a later interview with CTV Newsnet, Dion noted that Harper cancelled the Liberals' climate change plan but didn't replace it with anything.

"I think it's unacceptable. (Harper) needs to do more, not less," he said. "We need to honour our Kyoto target."

The Liberal government signed the Kyoto Accord on climate change in 1997 and ratified it in 2002. The party's climate change plan wasn't introduced until April 2005.

Kyoto calls for Canada to cut its greenhouse gas emissions by six per cent below 1990 levels by 2012.

As of 2004, Canada's emissions have risen 24 per cent above those 1990 levels.

Speaking in Vancouver on Monday, Baird accused Dion of doing nothing on climate change during his time in cabinet.

Dion became the environment minister after the 2004 election.

Toxins

Harper dodged a question about how much money he was willing to spend on fighting climate change and pointed to a $300-million commitment for a toxic chemicals plan.

"If I can be blunt, we're going to work with industry to set some targets, then industry is going to have meet those targets," he said. "I don't think we want the taxpayer being the one to pay to clean up air quality."

Dion said: "We'll see the kind of change's he'll make, but I'm afraid it will only be pretend changes."

While Harper listed 200 chemicals to be managed under his plan, Dion said scientists told the Conservatives to list 400 within six years.

"So he's doing the minimum in order to pretend that he's doing something," Dion said.

"But if we continue with this approach, we'll miss the train. Canada will not be on the podium of an industrial revolution, and this one is the one of the sustainable economy. We can't afford to miss it."