The Harper government is temporarily standing on the sidelines as international negotiations ramp up for a United Nations climate conference at the end of this year.

The conference scheduled for Paris in December is supposed to result in a post-2020 global agreement on cutting greenhouse gas emissions — a successor to the Copenhagen accord signed in 2009.

To help the negotiations, countries that are ready have been asked to submit their emissions targets and climate plans by March 31, a Tuesday deadline Environment Canada says it won't meet.

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The United States is expected to announce its post-2020 emissions targets today or Tuesday, but had already broadly laid out its goals in announcing a climate deal with China last November.

In the meantime, the U.S. and Mexico agreed to a joint task force on climate policy co-operation on Friday after Mexico announced its emissions will peak by 2026 and fall 22 per cent below "business as usual" levels by the year 2030.

Mexico is the first developing nation to submit its nationally determined contribution to the Paris organizers.

The Harper government, which has repeatedly stressed that Canada's climate policies must be co-ordinated with our continental trading partners, is not party to the new U.S.-Mexico task force.

Nor will it submit its emissions targets to the summit organizers this week.

"Canada wants to ensure we have a complete picture of what the provinces and territories plan before we submit," a spokesman for Environment Minister Leona Aglukkaq said in an email Sunday.

Ted Laking said the government will submit its nationally determined contribution "well in advance" of the December summit, as organizers have asked.

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"Because this is a national contribution and the provinces have targets of their own, we are collecting information on how they intend to meet their targets."

As for the U.S.-Mexico climate deal, Laking said it "emulates much of the work that Canada is already undertaking bilaterally with Mexico and the U.S., including regulatory alignment, collaboration on more energy efficient electricity grids and clean energy."

A U.S.-Mexico joint statement posted Friday by the White House stressed "the importance of jointly addressing climate in their integrated economy."

"The two countries will seize every opportunity to harmonize their efforts and policies toward their common climate goals," said the statement, including cooperation on everything from grid modernization and appliance standards to global and regional climate modelling.

Canada and the United States signed off on what was called a Clean Energy Dialogue in 2009, which included working groups on specific areas such as automobile fleets and transmission grids.

More recently, Prime Minister Stephen Harper said in a year-end interview last December that Canada can't regulate its oil and gas sector without coordinating with the U.S. and Mexico.

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"We've said for some time, it's very public, we're seeking a continental response on this particular question, not just with the United States. We'd like to see Mexico as well in it," Harper told the CBC.

However government statements in recent years have not reflected any substantive talks, let alone agreement, between Canada and the U.S. on common regulation of their oil and gas sectors.

Louise Comeau, the executive director of Climate Action Network Canada, said in an interview the U.S.-Mexico task force appears similar to bilateral groups set up by the Americans with China and India.

"Mexico has put on the table a pretty significant target and indicated it is prepared to negotiate," further cuts, she said.

Comeau says it is important to get those country contributions on the table now in order for summit organizers to analyse the many different models well before the Paris meeting. Failing to do so "constrains the whole negotiation," she said.

But Comeau agreed Ottawa ultimately will need to know what additional measures Ontario and Alberta are planning as part of Canada's national contribution. The Ontario government has promised to bring in a carbon-pricing scheme this year — likely in June — while Alberta is overdue to renew and strengthen its carbon tech fund for large emitters.

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Canada will need to cut its emissions by roughly a third from current levels by 2025 in order to keep pace with U.S. targets, said Comeau, and provincial efforts alone are not enough.

"To get there, the feds are going to have to put something on the table," she said.