Quebec Premier Jean Charest urged the Harper government Monday to show climate leadership by making new emission-reduction commitments under the Kyoto Protocol.
Mr. Charest is participating in side sessions during the United Nations summit on climate change, which is negotiating toward a global agreement on emissions reductions.
The Harper government has resisted calls for new targets under Kyoto to cover the post-2012 period, after current commitments expire.
Mr. Charest, whose criticism of the Tories at last year's Copenhagen summit drew a rebuke from then-environment minister Jim Prentice, again signalled his opposition to Ottawa's negotiating position, calling for a clear commitment to extend the Kyoto Protocol.
"I would want Canada to commit to that," he told reporters. "I know that is not the case, but we do not agree with the Canadian position."
The embattled Quebec Premier, who has plunged in opinion polls at home, is taking a prominent role in meetings of sub-national governments in Cancun.
He said Canada will be severely affected by global warming and changing weather patterns, particularly in the Arctic.
"We believe that the Canadian position should go further than saying that our position is that of the United States," he said.
"Given the impact of climate change on Canada . . . our belief is that we should be a lot more aggressive in commitments to reducing greenhouse gases."
Environment Minister John Baird says Canada wants a new treaty that binds all countries, including large developing nations like China and India.
But the European Union is backing developing world demand that any new agreement be an extension the Kyoto accord, which does not include binding commits for poorer countries.
Negotiators do not expect to conclude a deal this week in Cancun but hope to make enough progress to reach a final agreement next year in South Africa.
The Quebec government reported Monday that GHG emissions in the province in 2008 were 1.2 per cent below 1990 levels. Canada's levels remain well above that Kyoto target of 6 per cent below 1990 levels.