Canada is imposing a carbon tax on four provinces that haven't fallen in line with the emissions reduction strategy of Environment Minister Catherine McKenna

Canada's federal government on Monday made good on an ultimatum to impose a carbon tax on four provinces that haven't fallen in line with its emissions reduction strategy.

A starting levy of Can$20 (US$15) per tonne of pollution imposed on Manitoba, New Brunswick, Ontario and Saskatchewan—all led by Conservatives—will add about 4.4 cents to the price of a liter of gasoline, and drive up other too.

Over the coming years it is scheduled to increase incrementally to Can$50.

Liberal Prime Minister Justin Trudeau, however, pledged to refund most of monies directly to taxpayers, with those who aggressively cut their emissions reaping the largest rebates.

Six other provinces are exempt because each has come up with their own or cap and trade system to help Canada meet its Paris Agreement target of reducing CO2 emissions by 30 percent from 2005 levels by 2030.

"Putting a price on pollution is the most affordable and effective way to cut pollution," Environment Minister Catherine McKenna said on Twitter, enlisting support from former California governor Arnold Schwarzenegger.

"Strange how today's Conservatives, including (Andrew) Scheer and (Doug) Ford, oppose this practical, affordable, market-based solution," she said.

Saskatchewan has gone to court to fight the levy, while Ontario's Premier Doug Ford has railed against it daily over the past two weeks, saying it is a jobs-killer and could trigger a recession—claims disputed by economists.

"It will make everything more expensive," Ford said in an online video showing him filling up a car at a gas station.

His government, after it was elected last June, pulled Ontario out of a California-led cap and trade system that would have met the federal standard.

Speaking to reporters, Conservative opposition leader Andrew Scheer said Canadians "can't afford" the carbon tax, and vowed to repeal it if his party is elected next October.

He declined, however, to present an alternate plan to meet Canada's international climate obligations until the election.