I say consensus, because among scientists there is no debate. Climate change is real, it is caused by us and it will cause devastating changes to our world if we don’t take decisive action.

Canada’s leaders all accept that climate change is real, and they speak a good game on the need to address it. But their actions, and their commitments on key projects, are oftentimes diametrically opposed to their supposed understanding of the issues.

Scientific consensus missing from Canada’s election campaign

The day after the debate, star NDP candidate Linda McQuaig caused controversy and was accused of going against party policy when she told CBC’s Power & Politics that “a lot of the oilsands oil may have to stay in the ground if we're going to meet our climate change targets.”

But all she did was paraphrase the latest scientific research. A study in the journal Nature looked at which carbon deposits worldwide need to be left in the ground to avoid “dangerous” climate change, and concluded that many known reserves, including 85 per cent of Canada’s tar sands, cannot be exploited.

In October 2014 Mark Carney, former governor of the Bank of Canada and now governor of the Bank of England, told a World Bank seminar that the “vast majority of reserves are unburnable” if global warming is to be held below 2C.

That’s the scientific reality, which all the electoral leaders, with the exception of the Greens’ Elizabeth May, did their best to ignore on Thursday night.

There was much debate over Canada’s environmental assessment process, which both the NDP and Liberals say the Conservative government has gutted and left incapable of producing a fair evaluation.

But the thrust of remarks by both NDP leader Tom Mulcair and Liberal leader Justin Trudeau was they would reform the environmental assessment process and thus win Canadians’ support for pipeline projects. That would be fine if the only concern of Canadians were the localized environmental impact of pipelines. But people are concerned about the climate impact of expanding the tar sands, (the output of which the Canadian Association of Petroleum Producers forecasts will increase by 140 per cent over the next 15 years), and expect leadership on the issue from the contenders to replace Prime Minister Stephen Harper.

A 2014 poll showed Canadians split in half on pipeline projects such as Energy East and Keystone XL. Public opposition appears to be growing rapidly, as a poll released in April of this year found that support for Energy East had dropped to 36 per cent nationally. Nevertheless, none of the main party leaders are willing to reject these projects, despite the fact that their economic impact is overstated, their contribution to climate change is irrefutable and they are supported by only a third of the population.

Taking a position is hard; promising an assessment is easy

When I interviewed Bill McKibben in June, the founder of climate advocacy group 350.org, he told me he considers U.S. President Barack Obama a climate denier.

“He accepts the climate science, says all the right things, but then he grants Shell a permit to go drill in the Arctic. That's a denial of the need to take dramatic, quick action.”

I was reminded of his words on Thursday, when leaders of Canada’s political parties spoke of the urgency of acting on climate change, then proceeded to promise to do the exact opposite.

“The fact is we need to restore public trust in our ability as a government to create a level playing field upon which proponents of a project can acquire social license, can gain the public trust from the communities it’ll touch,” said Trudeau.

When needled by May on his refusal to take a clear position on pipelines, Mulcair shot back that “opposing these pipelines systematically in advance is just as wrong as supporting them in advance because, in both cases, what you need is an objective study.”

That sounds reasonable, doesn’t it? And it is. An objective study would make sense if we wanted to assess an unknown like, say, the impact of a pipeline on the land it would cross.

But we already have that rarest of commodities within the scientific community: consensus. Our best scientists, many of whom have been working on nothing else for decades, agree that the urgent need to transition off of fossil fuels means we can’t exploit and burn the majority of known reserves. The tar sands are at the top of the list of what can’t be burned, because they are more carbon intensive than other sources of oil.

So when Trudeau argues that “the job of the prime minister is to get those resources to market and in the 21st century that means being smart and responsible about the environment,” he’s denying the scientific reality. Being smart and responsible about the environment means choosing not to get all of that particular resource to market.

Canadians vastly overestimate the economic value of the tar sands to the economy, a 2014 poll showed. Non-conventional oil production accounts for only 2 per cent of national output, while manufacturing represents over 10 per cent, according to Statistics Canada. The poll found that “41 percent of Canadians think the oilsands contribution to the economy is between 6 and 24 times higher than it is.”

Watching their performance in the debate, one wonders if the leaders of the three main federal parties are included in that 41 per cent.

Ostriches with heads in the sand

In an op-ed written for the Toronto Star in 2009, Gerald Butts, then president of WWF Canada and now a senior advisor to Liberal leader Justin Trudeau, called out “tar-sands supporters” and argued that the views of the national political leaders on the tar sands were “myopic.”

“While the rest of the world searches for a low-carbon path to growth,” wrote Butts, “we are betting the national economy on a carbon footprint deeper than even conventional fossil fuels.”

Like Butts, Trudeau and Mulcair are smart people and I have no doubt that they can read the science. They know that we can’t build more pipelines without expanding the tar sands to fill them, which scientists think will wreck our climate.

They also know that any damage to the economy from restricting the expansion of the tar sands can be offset by transferring economic subsidies given to oil and gas companies to the renewable energy sector and joining countries such as Germany in positioning our economy to take advantage of the transition to renewable energy.

But instead, all three leaders are acting like ostriches, planting their heads firmly in the sand and accusing anyone who raises the science of heresy.

Which brings us to the fourth leader on stage Thursday, Elizabeth May. Ricochet’s editorial board live-tweeted the debate, and our consensus was that she won. She repeatedly grilled the other leaders on their contradictions and made clear and concise interventions throughout the evening. She showed that she belonged and should be invited to all remaining debates.

But she leads a party with no chance of forming government, and on Friday clarified that she didn’t want to shut down the tar sands, and instead advocated refining the oil at home. There’s an argument to be made for doing so on economic grounds, but it doesn’t address the climate impact.

Both Trudeau and Mulcair have spent months trying to speak out of both sides of their mouth on pipelines. Both have given French-language interviews that were interpreted to indicate their opposition to the Energy East pipeline, and both scrambled to clarify in English that they do not oppose the pipeline, although they don’t support it either. The fact of the matter is they have no position.

Arguing that you’ll reserve judgement on the most scientifically studied subject on earth until you conduct a new and improved environmental assessment is disingenuous. The job of politicians is to take positions on controversial issues and then argue their case in an election campaign.

By refusing to take a position on the most serious threat this country faces, our leaders are abdicating their responsibility to lead and denying the scientific reality of climate change.