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Previous climate change models of northern forests have failed to take the impact of such insect infestations into account, the study says. A team of researchers led by Werner Kurz of the Canadian Forestry Service measured the cumulative and individual effect on the carbon cycle of forest fires, logging and tree deaths due to beetles. The impact of the beetles alone has "converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak," the authors conclude. Kurz calculated that by 2020 the beetle outbreak will have released 270 megatons of C02 into the air, more than "the total average sink of all of Canada's managed forest over the last decade." This points up the often unpredictable interplay of factors influencing global warming, and how a single element can be both cause and effect. Earlier research has shown that pine beetles have thrived in Canada in recent years due warmer weather. "Climate change has contributed to the unprecedented extent and severity of this outbreak," concludes the study, published in the British journal Nature. Now the beetles are speeding up that very process. Forests are only one of the Earth's major carbon sinks. Recently scientists have found that the Southern Ocean and the North Atlantic have lost some of their ability to absorb C02. They fear that the same could be true of all the planet's oceans, which together absorb a quarter of man-made carbon dioxide emissions every year. Related Links: |
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