Quebec sovereigntists have wasted no time pouncing on the climate change issue as the latest argument to break up Canada, making their case at the very outset of a major UN summit.

The Parti Québécois issued the sovereigntist call to arms on the hot-button issue Monday as Prime Minister Stephen Harper prepared to attend the environmental conference at Copenhagen.

The PQ argued in an open letter that if international sanctions are eventually imposed on environmental laggards, "Canada's irrresponsible position" could wind up hurting Quebec industry.

That opening salvo underscored the national-unity minefield Harper will be wading through in Denmark as he searches for safe ground among the competing interests of Canada's provinces.

In her letter Monday, PQ international affairs critic Louise Beaudoin said "the non-sovereignty of Quebec has a price" — and that the cost of staying in Canada will grow with time.

"Quebec must get out of this regrettable position as quickly as possible," Beaudoin wrote in Montreal newspaper La Presse. "And to do this there's only one solution, getting complete independence."

Sovereigntists have been searching, and failing, for years to find an issue that rouses nationalist passions the way constitutional squabbles once did through the mid-1990s.

They had limited success more recently with federal-provincial fiscal disputes.

Their closest call may have come during the buildup to the Iraq war, which then-PQ premier Bernard Landry hoped to turn into a provincial election issue and argument for independence in 2003.

Hopes of a ride to independence on the coat-tails of an unpopular war were dashed by then-prime minister Jean Chrétien, who announced that Canadian soldiers would not participate.

In this case, it's not just Quebec but the three most populous provinces that may be aligned against Ottawa.

Harper is already taking heat from the governments of Quebec, Ontario and British Columbia, who have adopted aggressive emission-reduction targets that exceed federal proposals.

Those provinces are worried, however, that their success in lowering emissions could give other provinces — especially Alberta — wiggle room on their targets in the overall scheme of things.

The Bloc Québécois has already accused Harper of being soft on Alberta, whose economy is based on fossil fuels, at the expense of less-polluting provinces.

One political scientist said the climate-change issue may have presented sovereigntists with an ideal wedge to drive between Quebec and Canada.

"There is a distinct disconnect here between the Quebec position and the federal position based on interests that are very easy to identify and understand," said Pierre Martin of the Université de Montréal.

While it's still possible to turn things around, Martin said the issue could be useful to sovereigntists if it festers because it's a new angle and it's easy to understand.

Although the environment hasn't proven pivotal with voters before, he said the game-changer would be any sanctions on poor performers.

Because it would be included in Canada's tally, Quebec could still get nailed even though it has achieved major emissions reductions in recent years, Martin noted.

"Quebec's exports would be taxed just as if the greenhouse gas emitting operations were taking place on our own territory," Martin said. "There is a potential for a potent economic issue that people can easily understand and that makes sense."

Martin said Premier Jean Charest could fend off the sovereigntists in Quebec by being tougher on the federal government, entrenching himself as the best defender of Quebec's interests.

That might explain why Charest has long planned to be in Copenhagen. The pro-Canada premier announced his attendance at the summit well before Harper.

"That, for [Charest] has been a good strategy in the past, when he has shown what people would call spine in his relationship with the federal government," Martin said. "This is an issue that he could exploit."

A new poll Monday illustrated possible divisions in the country.

A pair of oil-producing regions – Atlantic Canada and Alberta – were the only two places in the country where less than a majority favoured a new binding treaty in Copenhagen.

Respondents in every other province expressed majority support for a new treaty in the Harris-Decima survey, provided to The Canadian Press.

In Quebec, 66 per cent were in favour, while it was 53 per cent in Ontario and 52 per cent in B.C.

In Alberta, 49 per cent supported a new treaty and the figure was 45 per cent in the Atlantic provinces.

Harris-Decima polled 1,000 people between Nov. 26 and 29, and their survey is considered accurate to within 3.1 percentage points, 19 times out of 20. However, provincial and regional numbers have a larger error margin because of their smaller sample sizes.