Carbon-rich wetlands in the Northwest Territories. (Chad Delany, Ducks Unlimited)

Boreal forests store more than double the carbon originally thought, yet policy-makers overlook their role in fighting climate change, says a report released Thursday by an international conservation group.

"For reasons that are unclear, boreal forests seem to be the carbon the world forgot," write the authors of a report published by the Seattle-based International Boreal Conservation Campaign (IBCC).

When climate change negotiators consider forests' carbon storage potential, they usually look at tropical forests because they are being logged at a faster rate than the northern boreal, said ecologist and report co-author Jeff Wells.

But soil in boreal forests — like those found in Canada's north — is much deeper than in tropical forests and hence stores much more carbon, said Wells, a visiting fellow at Cornell University.

Yet scientists have only recently taken into account the boreal's deeper soils and slower rate of decay of leaf litter, which also stores carbon.

"There were a series of estimates around 2000, 2001 that put the amount of carbon in boreal regions at between about 400 and 700 gigatonnes. And in the last year, the published estimates place it at two to three times that," said Wells. "But those 2000 to 2001 estimates have been what people have been using."

The boreal forest consists of 25 million square kilometres, or 11 per cent of the Earth's surface, and stretches from Alaska and northern Canada to Norway, Sweden and Finland, into Russia and parts of China, Korea and Japan.

Carbon in boreal forests is stored in both trees and in underlying peat and soils. The report estimates the boreal forest stores 22 per cent of all carbon on the Earth's land surface, making it the world's largest and most important terrestrial carbon storehouse.

That's significant because the more carbon that stays in the forest, the less carbon dioxide ends up in the atmosphere where it traps heat and radiates it back to Earth.

University of Victoria climate scientist Andrew Weaver, a lead author for the Nobel Prize-winning UN Intergovernmental Panel on Climate Change, reviewed the IBCC report. He said keeping carbon in place is an important part of the climate change equation.

"If you cut down the boreal forest and disturb its peatlands, you release more carbon, accelerating climate change," Weaver said in a news release.

Canada's boreal forest.

The report's authors stress that Canada has an important role to play because much of its boreal forest is still intact. They write that Canada's boreal stores the equivalent of 26 years worth of global carbon emissions from burning fossil fuels.

"If you hold in your hands, figuratively, a huge chunk of the carbon that will decide the fate of the world, it makes it clear the policies that are put into place in Canada are going to be really important," said Wells.

As the most intact remaining forest on Earth, the boreal forest is also going to be an important refuge for plants and animals forced to shift due to climate change, he added.

In 2008, Ontario announced a plan to prohibit development and commercial activities in a 225,000-square-kilometre area of the boreal, representing about half the province's boreal forest.

Also in 2008, Quebec said it would create 23 protected nature reserves containing 18,220 square kilometres of land to shield them from any industrial activity. Much of the land is in southern Quebec and includes boreal forests.