As Canada's 43rd election campaign winds down, climate change has emerged as one of the top issues for Canadians ahead of the vote.
And when it comes to ranking the climate plans of Canada's federal political parties, there are some well-defined contrasts.
"The one thing that's clear is that the weakest is the Conservative platform," said Kathryn Harrison, a professor of political science at the University of British Columbia (UBC) who has studied climate change for about 15 years.
"The Conservatives say that they're committed to the same targets as the Liberals, which is Canada's commitment under the Paris Agreement, but they haven't put forward a plan with credibility to meet that," she said.
"They've said that they'll undo various things that the Liberals have proceeded with, the big and most visible one is getting rid of the national carbon pricing plan and the federal carbon tax."
Simon Fraser University (SFU) professor Mark Jaccard estimates that emissions would go up under the Conservative plan, Harrison said, while environmental economist Dave Sawyer was a little more optimistic.
"[He believes] emissions would go down, but not by as much as with the Liberals, and that the gap between Canada's current plan and our 2030 target would be bigger," Harrison said.
The Liberals are "essentially running on their track record with a few tweaks," she added.
"The interesting thing is the NDP and the Greens both have much more ambitious climate policies, but they have less detail provided for how they would get there," she said.
"Their theme is sort of a Canadian version of the Green New Deal to fund transition of workers in communities away from fossil fuels, create new green jobs, and to pay for that by reducing fossil fuel subsidies. They also propose to phase out the compensation that industrial polluters get under the current government's plan."
In comparing the two, Harrison said the Green plan is like the "NDP's on steroids," though both, while ambitious, are lacking in detail.
"Partly that's because they haven't had the machinery of government at their disposal for the last four years as the Liberals have, and they're small parties, but also that the scale of ambition that the scientists in the IPCC (Intergovernmental Panel on Climate Change) are calling for is kind of beyond what we talked about," she said. "It's beyond what we've modelled thus far, so I think there is genuine uncertainty, [and] I cut them some slack for the uncertainty."
Harrison invoked Canada's effort during the Second World War as a comparison.
"We didn't say, 'Are we absolutely certain of what it's going to cost, and that we'll win?'" she said.
"And so I think they're taking that sort of approach rather than, 'Here's exactly what we're going to do, here's exactly the emission reductions that will result.'"
Villy Christensen, a UBC professor specializing in ecosystem modelling and a lead coordinator for the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, offered a similar assessment.
"[The Greens] are certainly up there at the top, the NDP is doing quite interesting things too, on their proposals, and let's say the absolute bottom is the Conservatives," Christensen said.
"Liberals are middling ... the disappointment from their taking over the Trans Mountain pipeline is of course a major factor in the credibility of the Liberals."
But which of the plans is most realistic?
"I think it's unambitious, in all cases, actually," Christensen said.
"I really think that Canada needs to realize that there are very viable alternatives to fossil fuel, the development of alternative energy is moving at a fast pace in Europe, and it's not really happening in North America," he said.
"I really think it needs to happen here, because it's viable, and the question is, does Canada want to be a follower or leader? The leaders are going to be making a lot of money on this in the coming decades."
But it's not just a future financial case to be made—Canada is already feeling the effects of (and paying the costs for) climate change.
"If you start talking to Indigenous peoples [up north], they are seeing dramatic changes in terms of disappearance of ice and snow, new species arriving, permafrost melting, and methane being emitted in lakes and that kind of thing," said Deborah Harford, executive director of the Adaptation to Climate Change (ACT) team at SFU.
"There's really big changes going on, but the trouble we find is that if people are living in fairly affluent lifestyles in a city, sometimes they are just not aware."
A report released last month by the Council of Canadian Academies titled Canada's Top Climate Change Risks (which Harford contributed to) identified 12 major areas of climate change risk before narrowing it down to a top six: infrastructure, coastal communities, northern communities, human health and wellness, ecosystems and fisheries.
"What [the report] does is it sends a clear message to Canadians across the country that these are the risks that we need to grapple with, and in fact that insurers, and planners and engineers and all levels of government are already dealing with the costs from," Harford said.
"We don't want those costs to keep rising; we want to avoid suffering and harm and loss and damage, and so we want to be proactive given that those risks are predictable and measurable and already happening."
As for the People's Party of Canada's assertion that there is no climate emergency, and that "there is no scientific consensus" that CO2 produced by humans is causing climate change, Harford, who has studied climate change for 13 years, said it's a "waste of time."
"If you study the science, it's very, very clear, and the sad thing is that people are being affected already," she said.
"People are already losing their livelihoods, losing their houses, losing things they care about, and they're worried about their children and their grandchildren, and we don't have time to waste."
Both Harrison and Christensen offered similar sentiments.
"I think it's ridiculous in an advanced industrialized country like Canada that we would have candidates running for office that are rejecting an extremely strong and international scientific consensus," Harrison said.
"If you went to the doctor with a fever and the doctor said this is going to keep getting worse until you get treatment, most of us would believe just that one doctor, and in this case, this is the equivalent of thousands of doctors giving us the same advice, and I think the People's Party is just rejecting it."
As for a Sept. 23 letter penned by 500 scientists and sent to the UN declaring there is no climate emergency, Harrison referred to an academic study on the nature of scientific consensus on climate change.
"[It] found that the tiny fraction of scientists who reject the consensus as reflected in IPCC reports are less prestigious scientists, they haven't been publishing, they are not scientists in the actual field of climate science," she said.
"I think the question is, can you find an academic scientist in the field of earth science, oceanography—you know, real climate science—who would challenge the IPCC consensus? I don't know of any.
"So I would look very hard at who those 500 people are."
When Christensen heard of the letter, he did just that.
"I looked through it just to see how many of the people I knew. I mean, out of 500 it must be quite a lot," Christensen said.
"It's mainly retired scientists who don't have much to lose in this ... I actually have quite a bit of faith in the science, having worked with many scientists in many countries on this."