Canadians will criticize the government for doing too much to tackle climate change once the economic impact is felt from reducing greenhouse gases, Prime Minister Stephen Harper said.

In a year-end interview with CBC's Peter Mansbridge, Harper spoke of the "challenge" of implementing the first phases of the mandatory emission reduction targets on industry because of the "very real costs" on the economy.

"There is a reason why previous governments have avoided at all levels setting mandatory emission targets." Harper said.

"As soon as you're dedicated to actually reducing emissions, that imposes costs on the economy. It imposes them in the short run."

While he said the costs will be manageable, they will provoke some reaction.

"And I'd ask your viewers to think of that whenever they have other people out there saying we should be doing more. Because once we start … these things start biting, the criticism we're going to be getting is that we're doing too much."

Harper said he is already starting to hear the first cries from industry and the provinces about the upcoming emissions targets.

Public inquiry not a sure thing

Harper was also asked about the public inquiry into the dealings between former prime minister Brian Mulroney and German businessman Karlheinz Schreiber.

Harper has named University of Waterloo president David Johnston to define the parameters for the inquiry. A final report to the prime minister is due by Jan. 11.

But the prime minister suggested that an inquiry is not a sure thing.

"I frankly have never wanted to make this call myself. I don't think Canadians would necessarily see me or this government as terribly objective on this matter," Harper said.

But when asked what might happen if Johnston advises him not to have an inquiry into the affair, Harper responded: "I think whatever advice David Johnston gives us, it's almost a certainty that that is the advice we will follow because from the beginning I have not wanted to be in a position of adjudicating what should or shouldn't be done with former prime ministers.

PM admits to feeling 'awkward'

"I feel extremely awkward about that. I feel particularly awkward in the case of Mr. Mulroney."

Harper was also asked about the recent isotopes shortage crisis and the government's decision to overrule Canada's nuclear regulator and re-start the reactor at Chalk River, Ont., which produces the medical isotopes.

He rejected he had made a partisan attack when he referred to the Canadian Nuclear Safety Commission as "Liberal appointed." He said he was just expressing his frustration with the regulatory body's decision. 

The shutdown had created a shortage of the nuclear material used for life-saving diagnostic scans and for medical imaging for fractures, cancers and heart conditions

"I don't believe the actions of the nuclear commission were motivated by partisan considerations," Harper said. "I do believe the course of action contemplated was extremely ill-advised. An appalling use of authority and judgment. And one that the government had to deal with."