EDITOR'S NOTE: This is the fifth in a series of articles from energy and environmental economist Andrew Leach about the federal political parties' climate plans. Read his previous articles here:

As climate change and energy have become one of the central issues in this campaign, I've had the chance to do a lot of writing and thinking about the platforms.

I've written assessments of the climate platforms of the Liberals, Conservatives, NDP and the Green Party as well as collaborating on a climate platform report card with Dr. Katharine Hayhoe.

Amidst the political talking points, there's a deeper issue that is being addressed: a national reckoning on climate change may well be the legacy of the 2019 election.

This campaign has offered three different visions for Canada's future climate change policies from the national parties.

The Conservatives have proposed a plan with a few token measures to reduce domestic emissions, and their most significant climate change policies are the removal of the federal carbon tax and the introduction of a subsidy to home energy consumption via a GST cut. Their suite of policies will, it's almost certain, increase domestic emissions. That's fine, the Conservatives say, because we're going to supply the world with the energy it needs and reduce global emissions in the process.

The Liberals , with all the advantages of incumbency, offer the middle of the road: an aggressive domestic policy but one that will need to get more stringent over time if we're to meet our existing emissions targets.

The NDP and the Greens each propose a rapid remaking of our economy, in particular in certain regions, with the hope of meeting much more aggressive near-term targets. This is what the science demands, they say.

(Not to be completely forgotten, Maxime Bernier thinks that climate scientists might have — despite his recent reminders — forgotten to consider the role of the sun. That's about all I'll have to say about the People's Party.)

Navigating Canada's climate reckoning demands a leader who understands a few things.

Climate science is crucial, but it's not enough.

Canada and its place in world

A leader should understand our economy and our place in the world, including the degree to which some regions of the country depend on fossil-fuel resources today.

A leader also needs to understand how to best reduce emissions: technology is important, but the right leader also needs to understand how policies can (or can't) change behaviour, the costs of those policies, as well as the limits to the powers of the federal government in Canada.

Finally, and perhaps most importantly, an effective climate change leader for Canada must show that he or she understands the distributional impacts of our choices, not just how they affect the average person or people like them.

I wish I could say that any of the leaders have ticked all these boxes so far. They haven't.

Perhaps more than anything during this campaign, I've been frustrated by lazy appeals to science.

What does the science tell us about Canada's emissions?

Listening to the NDP and the Greens, you'd think that a carbon budget for Canada is a law of physics. It's not.

Science tells us a lot about the impacts of continued increases in global emissions (the news is bad and, in general, getting worse) and that we're going to need a rapid decrease in global emissions (net zero or lower by 2050 to avoid warning of more than 1.5 C).

We know that reducing global emissions is going to require rapid changes in both how much energy we use and how that energy is supplied (see the graphs below). Finally, although our political discussion is focussed on binary targets, we know that climate-related risks increase the greater our emissions are, so any emissions reductions are beneficial.

But, what of Canada?

Today, we're less than two per cent of global emissions. On its own, Canada is not going to do much to mitigate climate change, even though all emissions reductions are beneficial at a global scale.

If we're relying on science alone, it must be said that there is no necessary or sufficient level of Canadian action that will ensure that we will meet (or prevent us from meeting) the 1.5 C or 2 C targets.

The fact that we're a small emitter should not be an excuse for inaction, but neither can we assume that other countries will mirror our policies.

I'd like to see our leaders ask a simple question of their plans: if the rest of the world implemented our policies, would we meet global goals?

For me, the 2030 coal phase out, a carbon price at $50 per tonne by 2022, and clean fuel regulations proposed by the Liberals, as well as the more aggressive policies proposed by the NDP and the Greens pass this test. The Conservatives? Not so much.

Leadership also requires understanding our economy today.

The cost of transition

Whether you like it or not, mining and oil and gas constitute about one fifth of our foreign direct investment, and activities directly related to fossil fuel extraction are about 10 per cent of our GDP.

Our most emissions-intensive industries directly employ hundreds of thousands of Canadians, with many more jobs linked to these activities directly via supply chains and financial transactions or indirectly via municipal, provincial and federal taxes.

National shares also hide regional and local concentrations: in some parts of the country, everything is connected to oil and gas or coal power, and an end to that industry is an end to the community.

There is no just transition which can cushion a region fully against government policy that shuts down its primary economic engine in less than a decade.

Leadership means acknowledging the real, human costs of policies, not pretending the costs don't exist. It also means acknowledging that these costs won't be spread evenly across the country just as our emissions (see below) are not evenly distributed.

While Canada won't solve climate change on its own, we are very exposed to the potential actions of others when or if they come to act aggressively on this problem. So, let's talk about what happens if the world acts on climate change, because for the most part, the leaders haven't been.

If the world acts on climate change aggressively enough to meet global goals, it will mean less global oil demand.

In all the model runs used to develop the IPCC 1.5 C report , there are no scenarios in which the world acts aggressively on climate change and continues to use more oil year over year: the math just doesn't work. Even the global oil majors agree on this point.

Pipelines have been a source of a lot of discussion during this campaign. It's obvious that, if we're not going to produce more oil, we don't need more pipelines.

I'd rather see our leaders justify whether, in a world in which action on climate change is lowering oil demand, we should be producing more oil here.

The Liberals would answer yes, the Greens and the NDP would answer no, and the Conservatives would likely answer that they don't believe world oil demand is set to decrease, so we should build all the pipelines.

Gas is more complicated. Using the same model runs, some predict significant declines in gas production but some also see gas as a bridge fuel allowing a rapid phase-out of coal.

Unlike oil, we can't say with any confidence that a world acting on climate change, even with the aggressive 1.5 C goals, needs to use less gas in every year in the future than we use today.

So, what of campaign claims about LNG? Is there more than a grain of truth in Scheer's claims that producing more Canadian LNG will reduce global emissions? Perhaps.

The answer depends on whether you believe that, if we don't win the race to supply the world with LNG, someone else will claim that market share. If there's going to be LNG available to China no matter what Canada does, it's not fair to claim that whatever we do will reduce emissions by as much. But, even then, insofar as our LNG supplies are lower emissions than the potential alternatives, that would reduce emissions.

The science does not say that no more gas should be developed anywhere on earth if we're to meet climate change goals, and it's not clear at all that more Canadian LNG is harmful rather than helpful to the global energy transition.

So, why am I not giving much credence to Scheer's claims on the role of Canadian LNG in reducing global emissions?

I'd give him a lot more credit if there were any chance he'd be willing to entertain a similar discussion about substituting away from the highest-emissions barrels in Canada's oil sands (which are among the most emission-intensive barrels produced in the world). He's not. And, since some of you are likely to take issue with this claim of mine, I've included a graph below.

Now, what about policies?

Pricing vs. regulating

You've all heard economists drone on about how carbon prices are the most cost-effective means to reduce emissions. That doesn't mean they'll necessarily be the most effective: a stringent regulation will lead to more emissions reductions than a weak carbon price every time, so we should not dismiss out-of-hand platforms without a carbon price.

We do know that regulations are more costly, all else equal, and demand more from government than carbon prices do. We also know that subsidies and taxes can be very expensive policies, not because they don't change behaviour in some people, but because they often pay people for doing what they would have done anyway.

The Liberal, NDP and Green plans each rely on a mix of pricing, subsidies, and regulations, while the Conservative plan is more reliant on tax incentives, subsidies and talking down emissions with encouraging words from the government.

Next to the lazy appeals to the science, one of the things that most disappointed me in the campaign was Scheer's leaving on the shelf arguably the most stringent climate change plan ever proposed by a Canadian federal government: the 2007 Turning the Corner plan. Don't believe me? Have a look . The Conservatives adopted many of the policies from the Harper era, including the transit pass credit and home retrofit subsidies. They missed the good one.

There's definitely a conservative answer to the risks posed to our economy by climate change and I wish we'd have seen a better push in that regard from Andrew Scheer's team.

Whatever your preference, I hope you'll take the time to vote. And thanks for reading.