NDP Leader Tom Mulcair today announced further details of his plan to create a national system to limit greenhouse gas emissions.

"I will make Canada the global leader in the fight against climate change," he said to supporters during a town hall meeting in Toronto.

The NDP has already promised, during campaigning for the Oct. 19 federal election, that it will establish a national cap-and-trade system to make big polluters reduce their greenhouse gas emissions. It aims to reduce emissions by 80 per cent by 2050, compared to 1990 levels.

But the detailed plan shows that an NDP government won't impose that national plan on provinces like Alberta, B.C., Ontario and Quebec that have developed their own systems to control emissions.

Instead, it will allow the provinces and territories to opt out as long as their carbon-pricing plans are equal to or better than the federal objectives.

The NDP has faced a lot of questions about how it would impose a national cap-and-trade system on provinces that have already spent money and time developing their own plans in the last 10 years. But Mulcair said on Sunday that the plan would be developed in collaboration with the provinces, territories, cities and indigenous governments.

'You don't reinvent the wheel'

Quebec has an operating cap-and-trade system. Ontario is in the process of developing a similar one. B.C. has a carbon tax and Alberta has just introduced a new rule to double its levy on carbon and make the oilsands industry cut the emissions intensity of each barrel of oil.

"You don't reinvent the wheel. If somebody's already doing some part of what you're asking them to do and they're getting the result that you're hoping for, you don't move in and replace it — you bring it in," the NDP leader said. "So I'm not going to tell the provinces to remove something that's working."

"For the other provinces, we'll be putting something in place that they'll be able to adhere to. The important thing is getting that result."

NDP Leader Tom Mulcair announced details of the party's plan to reduce greenhouse gas emissions during a campaign stop in Toronto. The plan would create a national cap-and-trade system, but allow provinces with their own equivalent objectives to opt out. (Andrew Vaughan/Canadian Press)

Liberal candidate Jody Wilson-Raybould told CBC News in an interview it was "interesting" that Mulcair is making promises similar to those he criticized months ago, referring to when the Liberals announced their environmental policy. The NDP had criticized the Liberal plan as "half-baked."

Wilson-Raybould, who's running in B.C.'s Vancouver Granville riding, said a Liberal government would sit down with the provinces and territories to come up with specific targets and an overall framework after attending the climate conference in Paris. A Liberal government would provide support to the provinces in designing their own plans, she said.

Revenues to be put back into provinces

The Conservatives have taken a sector-by-sector approach, but have faced criticism for their lack of national regulations to control the country's largest source of emissions — the oil and gas industry.

However, the Tories stand by their record.

"Under Prime Minister Harper's leadership, we are the first government in Canadian history to reduce greenhouse gas emissions, while protecting the Canadian economy and jobs. The NDP and Liberal carbon tax will kill jobs, upset our fragile economy and raise the cost of everything, including: gas, groceries, and electricity," Conservative campaign spokesman Chris McCluskey said in an email to CBC News.

Mulcair stressed that today's proposal would not become "a revenue generator for the federal government."

The plan is revenue neutral, he said, meaning that the government will be receiving the same money in taxes. Revenue raised by putting a price on carbon will be plowed back into the provinces to help them cut greenhouse gases.

"They're going to have the possibility of bringing in things like new transit that will help reduce the pollution but will also help put money back in people's pockets."

Mulcair didn't specify what the price on carbon would be, but that it is "a function of the market."

Plans would be brought to Paris summit

He said that the targets will be embedded within a Climate Change Accountability Act, which was first introduced in Parliament by the late NDP leader Jack Layton. He said the party would reintroduce the bill in the coming year.

The Pembina Institute, a think-tank focused on energy, said it applauds the NDP's commitment, saying their "targets are much more ambitious than Canada's current pledge."

"We are also pleased to see the NDP reaffirm its commitment to put a price on carbon pollution nation-wide, with a minimum level of stringency. When designed appropriately, a carbon pricing policy — such as a cap-and-trade system — encourages businesses and individuals to make cost-effective emissions reductions, and will help Canada compete in the global transition to a low-carbon economy," it said in a statement.

NDP leader Tom Mulcair says the NDP will introduce hard limits on greenhouse gas emissions and price carbon through a national cap-and-trade system. 3:23

Sources said the environment announcement is a big part of the "global leadership" focus of Mulcair's election campaign this week, which includes taking part in the Munk Debate on Canada's Foreign Policy in Toronto on Monday.

Mulcair will then head north to Iqaluit to talk about his party's environment platform later this week — an area of the country that is already feeling the effects of a changing climate.

It's also the riding of Conservative incumbent Leona Aglukkaq, the federal environment minister.

Looking ahead, Mulcair said if he becomes prime minister, he would send a multi-stakeholder delegation to the Paris climate summit "with a plan and concrete targets."