NDP Leader Thomas Mulcair, the man most likely to become the next prime minister of Canada if it’s not Stephen Harper, either doesn’t understand what carbon pricing is, or is pretending he doesn’t.

Either prospect is alarming.

This was revealed during the Maclean’s leaders’ debate Thursday when moderator Paul Wells asked him whether internalizing the costs of the Energy East oil pipeline, which Mulcair has said is necessary for the project to become viable, would raise gasoline prices at the pump.

The honest answer to that question is, “yes”.

Indeed, the cap-and-trade program Mulcair is proposing for Canada is designed to do precisely that, by putting a price on something we have never priced before, industrial carbon dioxide emissions entering the atmosphere.

(Hence the term, “carbon pricing”.)

Carbon pricing through Mulcair’s cap-and-trade plan will be reflected in higher prices for all goods and services containing or using fossil fuels, meaning oil, natural gas and coal.

But here’s what Mulcair said, instead of answering, as he should have, with “yes”.

“Internalizing the cost, as I just said before with regard to sustainable development, making the polluter pay, that’s a normal rule of sustainable development. Otherwise you’re making everybody in society bear it. User pay, polluter pay, basic rules of sustainable development ...”

Mulcair’s answer was bafflegab.

The reason is that we, all of us, are the polluters.

We buy the goods and services that are produced using fossil fuel energy, which put greenhouse gas emissions linked to climate change into the atmosphere.

Internalizing that cost means placing a price on it, which cap-and-trade -- Mulcair’s plan -- does by raising consumer prices for most goods and services, since industry simply passes along this new cost to us that it incurs from buying carbon credits from the government, which are essentially permits to pollute.

Under Mulcair’s proposal, and contrary to what he said, he will indeed be “making everybody in society bear” this cost, because fossil fuel energy powers modern industrialized societies like our own and thus is involved in the manufacture, production, creation and transportation of most goods and services, including food.

By contrast, Green Party Leader Elizabeth May doesn’t shy away from this reality and, among the opposition parties, is the only one who talks about carbon pricing honestly.

She says her party would increase taxes on consumption -- the cost of gasoline at the pump would go up, along with almost everything else.

Then, May says, the Greens would return the entire amount raised through this new consumption tax in income tax cuts to Canadians.

This as part of a “carbon fee and dividend” program to discourage carbon-intensive consumption, while encouraging productivity and savings, since Canadians would get to keep more of the money they earn.

One can believe or disbelieve May’s pledge the process would be revenue neutral and that the government would return all the money raised through income tax cuts.

But at least May is clear she would raise prices by taxing consumption.

Similarly, Harper stuck to the facts during the debate when he warned: “A carbon tax is not about reducing emissions. It’s a front. It is about getting revenue for governments that cannot control their spending.”

Demonstrably this is true, at least the part about raising money for governments.

Norway’s carbon tax, the world’s oldest and most sophisticated, has raised a huge amount of money for the Norwegian government since it was instituted in 1991.

But government statisticians concluded long ago it hasn’t been effective in lowering emissions.

The reason is the government granted too many exemptions to it, to protect its domestic industries from foreign competition in jurisdictions that don’t have carbon pricing.

This is also what undermined cap-and-trade, proposed by Mulcair, in the world’s biggest carbon trading market -- Europe’s decade old Emissions Trading Scheme.

There, European governments exempted entire industries from cap-and-trade and gave out so many free carbon credits (each one entitling the bearer to emit one tonne of carbon dioxide or its equivalent) they outnumbered actual emissions.

Naturally, emissions went up, followed by the 2008 global economic crash, which lowered the cost of credits to the point where it was cheaper for industries to buy them than reduce emissions.

Harper briefly supported cap-and-trade in 2008, when it looked like the Americans would introduce it -- because he would have had to since we do 70% of our trade with the Americans.

That said, he’s right. Carbon pricing doesn’t make the planet cooler. It just makes governments richer.