This story is part of CBC News special coverage of climate change issues in connection with the United Nations climate change conference (COP21) being held in Paris from Nov. 30 to Dec. 11.
Canada's new Liberal government has upped the ante in the negotiations aimed at helping slow global warming, joining other countries at the Paris climate talks that say a previously agreed upon global target falls short of protecting everyone's interests.
Canadian officials said this week they would support a long-term goal of limiting rising average temperatures to within 1.5 C of pre-industrial levels, although 2 C remains the official target.
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Officials from 196 countries are in Paris for talks that have been extended into Saturday to pen a deal to combat climate change. A 29-page draft agreement shows one of the issues yet to be resolved is whether the group should aim to keep temperature warming below 1.5 C, 2 C or somewhere between the two figures.
The 1.5 C goal is ambitious, scientists say, but not impossible. Success requires immediate action from all governments, including Canada's, and enough buy-in from citizens to spark some big changes.
'Train's almost left the station'
A half-degree change in the target may not seem like much, but scientists say it means the world's average emissions would have to decline more sharply, over less time.
"1.5 degrees is a hope — perhaps a dream," says Rob Jackson, an environmental scientist at Stanford University in California. "As a practical matter, the train's almost left the station."
'That level of commitment is nowhere near strong enough.' - Rob Jackson, environmental scientist at Stanford University
If global carbon dioxide emissions continue to increase by two per cent each year, the world's average temperature could be 2 C hotter within 20 years and 3 C hotter within 30 years, according to a paper Jackson co-authored and published this summer.
It would only take about a decade to reach 1.5 C, he estimates, giving policy makers 10 years less time to reduce emissions.
The world would have to decrease emissions on average about four per cent a year to avoid surpassing the 2 C mark, he says. As developing nations still demand additional energy, Jackson says, countries like Canada would have to bear more of the burden and reduce their emissions by an extra one per cent.
The new 1.5 C goal about doubles those numbers. Jackson estimates average global emissions would have to shrink by 10 per cent or more each year.
Canada is currently committed to reducing emissions 30 per cent below 2005 levels by 2030.
"That level of commitment is nowhere near strong enough" to stay below the new target, he says.
"Nothing's impossible. But nothing like that has ever been done."
In 2006-14, Canada's emissions decreased by 0.6 per cent annually — and actually increased slightly between 2012-14.
He offers "a small glimmer of hope." In the past two years, "rapid growth" of emissions nearly flatlined without an economic slump, according to a commentary piece he co-authored in Nature Climate Change this week.
Canada, along with many other nations, Jackson says, would have to do things very differently to avoid rising above the 1.5 C target.
Push for 100% renewable energy in 35 years
The Canadian government must commit to converting to 100 per cent renewable energy over the next 35 years to stay below the 1.5 C mark, says Gideon Forman, a climate change policy analyst at the David Suzuki Foundation. (For a 2 C target, there would be "a little more time," he says.)
That means moving immediately to eliminate coal-fired power; ramp up investment in renewable energy like wind, solar or geothermal power; and rethink public transportation, he says.
Governments should invest more in making electric and hybrid cars readily available and appealing to consumers, Forman says, as well as electrifying public transit.
These changes may sound utopian, he admits, but Forman believes they're achievable by 2050.
It would take a carbon tax to make renewable energy more attractive, he says, and government regulation on all levels — like provincial governments promising to close their coal plants by a certain date.
He points to places in Canada where positive changes are already happening. Ontario, for example, announced this month it will spend $20 million to build electric vehicle charging stations. The province also already closed its coal plants, which helped reduce Canada's greenhouse gas emissions from electricity by 22 per cent over five years.
"It's quite practical," says Forman, who believes the current climate talks can spur governments into action.
Public support required
Even so, government can't tackle this issue alone. These types of changes require a lot of support from citizens, says Corinne Le Quere, a professor and director of the Norwich, England-based Tyndall Centre for Climate Change Research, who is in Paris for the talks.
"Without the people on board, it's really difficult to deploy across the board everything you need to do to really de-carbonize," she says.
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People would have to accept smaller and more electric cars on the roads, she says, and not complain about wind towers being built.
Their behaviour would have to change, Le Quere says. People, for example, might have to drive less and recycle more.
Citizens might also be forced to fork over some cash to invest in energy-efficient appliances or to better insulate their homes.
All that will be "very challenging" to implement in such a short time, Jackson says, but the rewards of limiting climate change make it worth trying to stay below either the 1.5 or 2 C mark.
"From a practical standpoint, if we could do 2 degrees C at this point, that would be fantastic."