TORONTO -- Polluters would have to pay for their actions under a plan to put a price on carbon and set limits for greenhouse gas emissions, New Democrat Leader Tom Mulcair said Sunday.

Speaking in Toronto, Mulcair laid out a platform he said was needed to restore Canada's environmental credibility shredded by the Conservatives under Stephen Harper.

"He's done absolutely nothing -- nothing but damage to our global reputation and to our planet," Mulcair said.

"Mr. Harper, you have abdicated responsibility on the environment."

An NDP government would develop a national cap and trade system that sets hard targets for the emissions most scientists say are contributing to global warming and potentially catastrophic climate change, Mulcair said.

Canada, he said, successfully adopted such a system decades ago to combat emissions that were causing acid rain.

Some provinces -- British Columbia, Alberta, Quebec and Ontario -- have already implemented their own measures on climate change such as implementing a carbon tax or cap and trade system.

Mulcair, a former Quebec environment minister, said provinces would be allowed to opt out of a national scheme if their efforts are as good or better.

"We're not going to replace something that's working," Mulcair told an enthusiastic crowd. "The important thing is to set the objective."

Details on those objectives would come at the UN climate change conference in Paris in December -- after consultations with the provinces and activist groups, he said.

To head off any criticism that he would be imposing a new tax, Mulcair said money raised from carbon pricing would go to the provinces to bolster their pollution-fighting efforts. He refused to say what the carbon price would be, saying the market will dictate that.

"Polluters will pay because it is not fair to ask Canadian families to clean up somebody else's mess," Mulcair said.

The NDP would also reintroduce a bill first proposed by his predecessor, Jack Layton, to ensure Canada meets long-term targets for reducing greenhouse gases.

Mulcair took repeated aim at both Liberal and Conservative governments.

The Tories have failed to regulate the oil and gas sector -- the single fastest growing source of emissions in Canada, he said.

Canada is the only country to have withdrawn from the Kyoto Protocol on harmful emissions, but the Conservatives say the agreement would not have helped combat climate change.

John Trent, a senior fellow at the Centre on Governance at the University of Ottawa, said Mulcair's cap-and-trade plan could let large corporations continue emitting by allowing them to trade their pollution for economic benefits from other companies or sources.

It is also a difficult system to implement, Trent said.

"You have to line up all the corporations and various parts of the country and various countries, and then you have to get them to abide by this."

Critics, such as the Canadian Association of Petroleum Producers, have argued increasing carbon prices would cost industry hundreds of millions of dollars but Trent said such pricing can be effective.

Erin Flanagan, an analyst at the Pembina Institute, welcomed Mulcair's announcement.

"When designed appropriately, a carbon pricing policy -- such as a cap-and-trade system -- encourages businesses and individuals to make cost-effective emissions reductions," Flanagan said.

A July 2014 analysis by Brattle Group international consultants recommended increasing Alberta's carbon tax to $50 a tonne -- a hike of almost 70 per cent -- would be the best way to reduce its harmful power-generation emissions.

Vancouver Liberal candidate Jody Wilson-Raybould said Mulcair failed as Quebec environment minister and is now making promises on climate change the NDP criticized a few months ago.

"Mulcair will say whatever is convenient," Wilson-Raybould said in a statement. "He advocated for the mass export of fresh water, tried to sell off pristine parkland and made headlines for his inaction on greenhouse gases."