It's hard to believe but Canada's forests are now a net contributor to global warming. From the World Business Council for Sustainable Development:
In an alarming, yet little noticed series of recent studies, scientists have determined that Canada's 1.2 million square miles of forests have become so stressed from damage caused by global warming, insect infestations and persistent fires that they have crossed an ominous line and now pump out more carbon dioxide than they take in.
The trees make up more than 7 percent of Earth's total forest lands and have been dubbed the "lungs of the planet" because they could always be depended upon to suck in vast quantities of carbon dioxide, naturally cleansing the world of some of the harmful heat-trapping gas.
But rising temperatures are slowly drying out forest lands, leaving trees more susceptible to fires, which release huge amounts of carbon into the atmosphere, Canadian officials say.
Higher temperatures also are accelerating the spread of the deadly mountain pine beetle, which has devastated tens of thousands of square miles of trees. Bitterly cold Canadian winters used to kill off much of the pine beetle population each year, naturally keeping it in check. But the milder winters of recent years have allowed the insect to proliferate.
The problem has become so serious that Canada's federal government effectively wrote off the nation's forests in 2007 as officials submitted their plans to abide by the international Kyoto Protocol, which requires participating nations to reduce their greenhouse gas emissions.
http://www.enn.com/ecosystems/article/39037
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