Canada became the first country to formally withdraw from the Kyoto Protocol, saying the pact on cutting carbon emissions was preventing the world from effectively tackling climate change.
"We are invoking Canada's legal right to formally withdraw from Kyoto," Environment Minister Peter Kent said following a marathon UN climate conference in South Africa, at which nations agreed to a new roadmap for worldwide action.
The landmark pact reached in 1997 is the only global treaty that sets down targeted curbs in global emissions.
But those curbs apply only to rich countries, excluding the United States, which has refused to ratify the accord.
"Kyoto is not the path forward for a global solution to climate change," Kent said. "If anything, it's an impediment.
"We believe that a new agreement with legally binding commitments for all major emitters that allows us as a country to continue to generate jobs and economic growth represents the path forward."
Canada agreed under the Kyoto Protocol to reduce CO2 emissions to 6.0 percent below 1990 levels by 2012, but its emissions of the gases blamed for damaging Earth's fragile climate system have instead increased sharply.
Saying the targets agreed to by a previous Liberal administration were unattainable, Conservative Prime Minister Stephen Harper's government last year unveiled its own measures aimed at curbing emissions, in line with US efforts.
Pulling out of Kyoto now allows Canada to avoid paying penalties of up to CAN$14 billion (US$13.6 billion) for missing its targets.
Kent also cited major impacts on Canada's economy that will be avoided by withdrawing from the treaty.
"Under Kyoto, Canada is facing radical and irresponsible choices if we're to avoid punishing multi-billion-dollar payments," Kent said, noting that Canada produces barely two percent of global emissions.
"To meet the targets under Kyoto for 2012 would be the equivalent of either removing every car, truck, ATV, tractor, ambulance, police car, and vehicle of every kind from Canadian roads or closing down the entire farming and agricultural sector and cutting heat to every home, office, hospital, factory, and building in Canada."
For Kyoto supporters, the anticipated Canadian pullout was expected to be a symbolic blow and badly damage a UN climate process already weakened by divisions.
Last week at the UN climate conference in Durban, South Africa, Kent had already said that Kyoto was "in the past" for Canada.
"It is an agreement that covers fewer than 30 percent of global emissions, by some estimates 15 percent or less," the Canadian minister said.
The conference on Sunday approved a roadmap towards an accord that for the first time will bring all major greenhouse-gas emitters under a single legal roof.
If approved as scheduled in 2015, the pact will be operational from 2020 and become the prime weapon in the fight against climate change.
But environmentalists have called it porous.
Kent said that in the meantime, Canada would continue to try to reduce its emissions under a domestic plan that calls for a 20 percent cut from 2006 levels by 2020, or as critics point out, a mere three percent from 1990 levels.
The latest data last year showed that Canadian carbon emissions were currently up more than 35 percent from 1990.
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