Negotiators at the United Nations climate summit are searching for broad agreement that will lead to a new treaty requiring deeper cuts to each country's greenhouse-gas emissions after 2020, even as Canada struggles to achieve its existing commitments.

In an interview from Warsaw on Sunday, Ottawa's climate ambassador Dan McDougall rejected suggestions from critics that Canada has no credibility at the global summit due to its failure to adopt policies that would meet emission-reduction commitments made by Prime Minister Stephen Harper at the 2009 meeting in Copenhagen.

In the run-up to the two-week summit in the Polish capital, both the federal government and the United Nations issued reports that suggest Canada is not on track to meet its commitment to reduce greenhouse-gas emissions by 17 per cent from 2005 levels by 2020. However, over the next few years, countries will be expected to make more ambitious commitments for the post-2020 period as part of a new treaty, which they have agreed to have in place by 2015.

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"There are a number of countries that still have further work to do and we're well aware of that," Mr. McDougall said Sunday. He said the federal government has implemented some policies as have provinces, and Ottawa remains committed to new regulations for the oil and gas sector that will slow the growth of emissions from sectors such as the oil sands.

But critics argue Canada will not meet its 2020 commitments unless the government adopts a far more aggressive stand than it has to date. Ottawa has delivered about $1.2-billion in aid to developing countries to help them address climate issues, and it is working with other nations to make good on a commitment to provide $100-billion (U.S.) in public and private sector funding by 2020 for that effort.

"There is a lot of work we're doing on both fronts, both domestically and internationally, so I think we do have a credible voice," Mr. McDougall said.

Heading into the summit, the UN's chief climate officer, Christiana Figueres, said it was crucial that countries stop bickering and find common ground to confront the urgent challenge of the warming climate. Governments have agreed to limit the increase to two degrees Celsius, but a UN report said countries are not on track to achieve the emissions reductions needed to meet that goal.

Negotiators are not looking for concrete commitments in Warsaw, but rather they will try to achieve common ground on the framework of such a deal. Canada insists that all major emitters – including countries such as China and India – make the same sort of binding commitments, though with differing level of ambition. Environment Minister Leona Aglukkaq will attend the second week of the summit.

"The issue for Canada is how do we get to a new, more ambitious and effective agreement that is applicable to all, so that we can get real emission reductions that are going to have the desired effect from a global perspective," Mr. McDougall said.

The UN reported last week that developing countries have caught up to the developed world in the amount of greenhouse gas emissions since 1850, and that those poorer countries – including China, India, Brazil and South Africa – now account for 60 per cent of annual emissions. Mr. McDouglall said he hopes this will help move the debate away from a focus on historical grievances.

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"There are some countries that continue to hammer away on this whole notion of historical responsibility and I don't think it's a particularly productive track to focus on," he said. "We're only going to solve this if we're all contributing to the maximum that we can."