(CNN) -- Canada officially renounced the expiring Kyoto Protocol on Monday, a day after international negotiators agreed to extend the treaty's limits on carbon emissions blamed for a warming climate.
Environment Minister Peter Kent said Ottawa would keep working to reduce its greenhouse gas emissions and help negotiate a new framework for a global pact.
But in a statement to reporters on his return from last week's climate conference in South Africa, Kent said that for Canada, Kyoto "is in the past."
Prime Minister Stephen Harper's Conservative government has long opposed the Kyoto protocol and has refused to implement it since taking office in 2006. Ahead of the decision, the opposition New Democratic Party accused his government of "standing up for big polluters" at the expense of ordinary Canadians and risking the country's reputation by abandoning the 1997 treaty.
Kent said Kyoto's goals were unworkable because the United States and China -- the world's two largest sources of carbon emissions -- never agreed to Kyoto, and that a new pact is needed to address emissions from rapidly growing economies including those of China, Brazil and India.
The government announced in 2010 that it would fall well short of the treaty's target of a 6% cut in emissions below 1990 levels by 2012. Kent said the previous government signed onto the treaty "without any regard to how it would be fulfilled," and that Canadians faced "radical" cuts or financial penalties equivalent to $1,600 per family as a result.
He said Canada was "well on our way" to reducing emissions by 17% over 2005 levels by 2020, but critics say that self-imposed goal is well below the Kyoto targets.
Nations in the Durban talks agreed to extend Kyoto's efforts over the weekend and launched an effort to set up a broader pact with a legal format to curb carbon emissions.
The talks also launched a Green Climate Fund, which would essentially channel about $100 billion by 2020 to vulnerable countries to help them deal with the effects of climate change.