OTTAWA -- "We actually saw greenhouse gases go down at the same time as taxes went down under the previous Conservative government. We saved people money while protecting the economy." -- Conservative finance critic Pierre Poilievre, May 1

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A battle over the merits of a carbon tax has been playing out between Liberals and Conservatives for more than a decade and is sure to be a ballot-box question again in 2019. The Liberals, who campaigned in 2015 on putting a price on carbon, promised to require every province to have a minimum price on carbon -- or Ottawa would do it for them.

A carbon price is the most cost-effective way to cut greenhouse gas emissions, they argue, calling it a necessary measure -- along with regulations on fossil fuel, gasoline and electricity production -- to meet Canada's emissions targets under the international Paris climate change agreement.

Environment Minister Catherine McKenna produced an analysis this week that declared a carbon price of $50 per tonne would eliminate between 80 million and 90 million tonnes of greenhouse gases, without significant impact on economic growth.

What the Liberals call a "carbon price" or a "price on pollution," the Conservatives bill as a "carbon tax" or a "tax on everything."

Last weekend, Conservative Leader Andrew Scheer threw down the gauntlet, promising a credible plan to meet Canada's targets without a carbon price. He has said tearing up the carbon price law will be the first thing he does if he becomes prime minister in 2019.

It was with that in mind that Poilievre told question period on Tuesday that the former Conservative government had already proven it's possible to cut greenhouse gases while growing the economy, all without a carbon price.

But did they really? Did greenhouse gas emissions go down while the Conservatives were in office and can Poilievre credibly tie it to tax cuts and economic growth?

Spoiler alert: The Canadian Press Baloney Meter is a dispassionate examination of political statements culminating in a ranking of accuracy on a scale of "no baloney" to "full of baloney" (complete methodology below).

This one earns a rating of "some baloney." Here's why.

THE FACTS

When the Conservatives were in office between 2006 and 2015, the government cut taxes in a number of ways, including by eliminating two points from the GST, as well as shaving points from both personal and corporate income tax rates.

According to the most recent national greenhouse gas inventory report, which Canada files every April with the United Nations, annual greenhouse gas emissions in Canada were around 732 million tonnes when the Conservatives came to office in 2006. In 2015, emissions were about 2.5 per cent lower at 714 million tonnes.

During that same decade, Canada's economy grew by an average of 1.5 per cent a year.

So on the surface, the first part of Poilievre's claim is true.

However, looking at annual emissions paired with economic growth, things get a bit more murky.

On a year-to-year basis, emissions went down only twice in that decade, and both drops were directly related to the 2008 financial crisis that led to the 2009 economic recession. As soon as the economy started growing again, so did emissions.

Federal and provincial governments alike were starting to undertake regulatory measures and policies to address emissions levels. So while the oilpatch saw emissions grow 25 per cent between 2009 and 2015, provinces were closing down coal-fired power plants and Ottawa was introducing policies to make vehicles more efficient. Those factors offset emissions growth in other areas; while emissions levels started rising again, they have never increased as much as they did before the recession.

THE EXPERTS

David McLaughlin, a former head of the federal Round Table on the Environment and the Economy and a recent policy adviser to Manitoba Premier Brian Pallister, said while it's true emissions went down during the Harper era, "that had very little to do with Harper government policies."

"There's a real difference between correlation and causation," he said.

The drop in emissions in 2008 and 2009 was almost entirely the result of shrinking economic growth, McLaughlin added.

"Charitably, I'd call it an alternative fact to make that case that Mr. Poilievre and Mr. Scheer are making."

There's simply no truth to the suggestion that emissions reductions during the Harper government had anything to do with tax cuts, he continued, calling it misleading to suggest emissions were declining even as the economy grew.

Moreover, the most effective government policies that kept emissions in check were provincial, not federal. McLaughlin cited in particular Ontario's decision to close all its coal-fired electricity generating stations, as well as the carbon pricing system imposed in British Columbia.

THE VERDICT

Poilievre is correct to say that during the time the Conservatives were in power, emissions went down, taxes were cut and the economy grew. However, emissions levels fell not because of tax cuts or proactive policy, but because of a bruising economic recession.

When it was over, emissions began to climb again, and the only thing that held them in check was a carbon price in B.C. and the end of coal-fired power in Ontario. For those reasons, Poilievre's claim contains "some baloney."

METHODOLOGY

The Baloney Meter is a project of The Canadian Press that examines the level of accuracy in statements made by politicians. Each claim is researched and assigned a rating based on the following scale:

No baloney -- the statement is completely accurate

A little baloney -- the statement is mostly accurate but more information is required

Some baloney -- the statement is partly accurate but important details are missing

A lot of baloney -- the statement is mostly inaccurate but contains elements of truth

Full of baloney -- the statement is completely inaccurate