Canada's forests, once huge help on greenhouse gases, now contribute to climate change

January 02, 2009|By Howard Witt, Tribune correspondent



But not anymore.



"We are seeing a significant distortion of the natural trend," said Werner Kurz, senior research scientist at the Canadian Forest Service and the leading expert on carbon cycles in the nation's forests. "Since 1999, and especially in the last five years, the forests have shifted from being a carbon sink to a carbon source."

Translation: Earth's lungs have come down with emphysema. Canada's forests are no longer our friends.



"The forecast analysis prepared for the government ... indicates there is a probability that forests would constitute a net source of greenhouse gas emissions," a Canadian Environment Ministry spokesman told the Montreal Gazette.




"That's what's causing some of our forests to switch from a carbon sink position to a source position," said Jim Snetsinger, British Columbia's chief forester. "Once those infested trees are killed by the pine beetle, they are no longer sequestering carbon -- they are giving it off."

Snetsinger noted that eventually, over the course of a generation, some of the dying forests will begin to regenerate and once again begin storing more carbon than they release. But for the foreseeable future, experts say, their models show that Canada's forests will stay stuck in a vicious global-warming cycle, both succumbing to the effects of climate change and, as they decay and release more carbon, helping to accelerate it.


Environmentalists contend that the extreme stresses on Canada's forests, particularly the old-growth northern forest, mean that logging ought to be sharply curtailed to preserve the remaining trees -- and the carbon stored within them -- for as long as possible.

Moreover, they argue that the disruptive process of logging releases even more carbon stored in the forest peat, threatening to set off what they describe as a virtual "carbon bomb" -- the estimated 186 billion tons of carbon stored in Canada's forests, which is equivalent to 27 years worth of global carbon emissions from the burning of fossil fuels.