Boreal forests -- the evergreen and birch woods that blanket the sub-Arctic -- store more carbon than any other ecosystem.
High latitude forests store more carbon than tropical rainforests, making them an underappreciated player in the future of global climate change, according to a new report.
Recent studies suggest that there may be as much as two to three times more carbon sequestered there than previously thought, the report said.
The boreal forest -- composed mainly of evergreen trees and blanketed in deep peat -- encircles the globe across Canada, Alaska, Siberia and Scandinavia, from near the U.S.-Canada border north above the Arctic Circle.
"As leaders assemble in Copenhagen next month, everyone will worry about tropical deforestation, for good reasons. It contributes 20 percent of global greenhouse gas emissions. That's more than the European Union." said tropical conservation biologist Stuart Pimm of Duke University, who reviewed the report.
"But -- and it's a very big 'but' -- if you look at where the biggest reserves of carbon are, they're actually in the boreal forests of Canada and Russia and that's because the forests there accumulate large amounts of carbon, especially in the peat."
"There is more carbon in the boreal regions of the globe than in any other terrestrial ecosystem," said study author Jeff Wells of the Boreal Songbird Initiative, headquartered in Seattle. "So far global accounting has vastly underestimated them."
Previous estimates put the total carbon in boreal forests at about 700 billion tons, compared to around 400 billion tons in tropical forests. Such estimates suggested that boreal forests contain twice as much carbon per acre as tropical forests, according to these estimates.
But most recent studies put those numbers at two to three times higher, Wells said.two Unlike in tropical forests, where most of the carbon is stored in living trees and plants, the majority of carbon in boreal forests is found in the peaty soil.
"The reason is quite simple," said Pimm. "If you go into a tropical forest and you stick your hand down into the leaf litter, pretty much underneath is some hard soil. There's not much in the way of good, old-fashioned muck. Do that in the boreal forest and you might have several feet -- or many feet. That means the carbon just sort of sits there and accumulates."
The colder temperatures keep decomposition rates slow, allowing litter to accumulate on the ground.
Vast stores of carbon are not the only reason to pay attention to the boreal forest. "The boreal, unlike most of the rest of the Earth, still maintains intact ecosystems," Wells said.
The area contains probably the world's largest populations of wolves, grizzly bears, wolverines and caribou. Because large, continuous tracts of untouched land still exist, species are free to move in response to climate change.
The boreal forest is a huge reservoir for North American birds. "We estimate there are 3 to 5 billion birds, mostly songbirds, that come spilling out of the boreal forests every fall," Wells said. These birds populate backyards across the United States through the winter.
But climate change and development threaten the boreal forest. Warming temperatures will release stored carbon by speeding decomposition, increasing fire frequency, and melting the permafrost that covers much of the boreal forest.
Development of mining, logging and oil and gas industries could disrupt the wildlife habitats provided by the forest, and expose the peat, allowing it to decompose and release its carbon.
"Our number one message in all of this is that we have to drastically cut industrial emissions," Wells said. "The boreal is one of the places that is more at risk than just about any other place from increased pumping of industrial emissions into the atmosphere. "
Nonetheless, there is good news, Wells said, especially in Canada. Over 125 million acres of Canadian boreal forest have been incorporated into parks and refuges since 2001. Quebec and Ontario provinces are planning on setting aside an additional 400 million acres for conservation, with at least half of that completely off limits to development.