Four years ago, Canada became the first country to withdraw from the 1997 Kyoto Protocol that set global targets to reduce greenhouse gas emissions.
A lot has changed since then.
On Monday, less than a month after being sworn in as Canada's 23rd prime minister, Justin Trudeau leads a Canadian delegation to the United Nations climate change summit in Paris, eager to negotiate a new global agreement.
"Canada is back," said Canadian Environment and Climate Change Minister Catherine McKenna at a news conference Sunday in the French capital.
Well-known Canadian environmentalist, scientist and broadcaster David Suzuki, who joined thousands in Ottawa on Sunday for a march in support of government action on climate change, credited Trudeau for quickly initiating "a massive reversal" in the Canadian government's approach to the issue.
Suzuki said that by contrast, Trudeau's predecessor, Stephen Harper, was "willfully blind" to climate change during the 9 1/2 years his Conservative government held power until it was defeated by Trudeau's Liberals in the federal election.
It was Harper's administration that pulled Canada out of the Kyoto agreement and was not on track to meet its own target of a 17% reduction in greenhouse gas emissions below 2005 levels by 2020.
However, as Canadian Foreign Affairs Minister Stephane Dion, a former federal Liberal leader and environment minister, reminded reporters on Sunday, the provinces have jurisdiction over electricity and natural resources. Many have taken the lead on climate action.
Ontario, Canada's largest province, is the first North American jurisdiction to permanently ban coal-fired electricity generation. It set targets of reducing greenhouse gas emissions by 37% below 1990 levels by 2030 — and by 80% below 1990 levels by 2050. Ontario is also collaborating with California and Canada's French-speaking province of Quebec to develop a cap-and-trade system that sets a limit on the amount of pollution industry can produce and a mechanism by which companies over their quota can buy carbon credits from those that don't use all of theirs.
Meanwhile, Quebec, along with the western Canadian provinces of British Columbia and, most recently, Alberta, have introduced carbon taxes. Alberta, whose oil patch has come under fire as a major polluter, has announced an aggressive plan to address climate change that sets limits on emissions and begins a transition from coal to renewable electricity sources.
Last week, in the middle of a whirlwind tour of international summitry, Trudeau discussed climate change with Canada's 13 provincial and territorial premiers in Ottawa, where they also heard from two of the country's top climate scientists.
"I'm certain that Stephen Harper never accepted a briefing on climate science," said Canadian Green Party leader Elizabeth May from Paris, where she is attending her 10th U.N. "Conference of the Parties" climate change meeting.
She hopes that Trudeau will show strong leadership on climate change and take a more aggressive approach to it than Harper, whom she accused of having "wrecked" Canada's global reputation on the environment.
A Canadian — Maurice Strong, who died Saturday at the age of 86 — was the founding director of the U.N. Environment Program and served as secretary-general of the Rio Earth Summit in 1992 that resulted in the U.N. Framework Convention on Climate Change.
But the international attitude toward Canada shifted during the Harper government's near decade in power, May said.
"At previous climate negotiations, I remember being hated because I was Canadian even though I was not part of the Conservative government," she said in an interview.
McKenna and Dion signaled from Paris that Canada is committed to introducing carbon pricing, and last week during a meeting in Malta of leaders of British Commonwealth countries, which include Canada, Trudeau announced a nearly $2-billion contribution over the next five years to help developing countries combat climate change.
At the climate summit in Copenhagen six years ago, industrialized countries committed to provide $100 billion annually to poorer countries by 2020, and environmental groups have urged Canada to embrace a 4% target, or $4 billion, based on its national wealth.
Those extra funds could come from a tax on bunker fuels used in international aviation and shipping, which if they represented a country would be among the world's top 10 polluters, according to Dale Marshall, national program manager with Environmental Defense Canada.
Trudeau "has to show that he not only leads a new government, but a new kind of government," said Marshall, who is also in Paris.
Nathan Cullen, the environment and climate change critic for Canada's left-of-center New Democratic Party, who will be in Paris this week, hopes that Trudeau's approach to climate change represents "more than just a shift in tone" from Harper and results in "real cuts" to emissions that were rising in the oil, gas and building industries under the Conservatives' watch.
However, Cullen, a member of Parliament from British Columbia, was troubled by McKenna's comments Sunday. She said any final agreement to emerge in Paris would require countries only to set emission reduction targets but would not feature an enforcement mechanism to meet them, as a way to ensure support from countries such as the United States, where the Republican-dominated Congress would not ratify a treaty imposing legally binding cuts.
"If the binding nature of a treaty is good enough when Canada is negotiating trade deals, why is it not good enough when we're trying to save the planet?" Cullen said.
Suzuki hoped the eventual agreement would set goals, not aspirations, to address climate change.
"This is like a war with 100 Pearl Harbors going off at once," he said. "That's how serious the situation is."