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The source of the destruction is a pine beetle, the Dendroctonus
ponderosae, which lays eggs under the bark of mature lodge
pole pines and jack pine trees, destroying them.
Once an infestation starts, the tree cannot be saved and
the rotting dead trees release, rather than absorb, carbon
dioxide.
So far, pine beetles have destroyed more than 50,000 square
miles of forest in Western Canada and damaged hundreds of
thousands of U.S. forests, turning green forests a reddish
brown color.
The global warming connection
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The pine beetle infestation is both a contributor to and
a symptom of global warming, which is made worse by human-generated
carbon emissions. |
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Usually, a healthy forest
acts as an absorber of carbon dioxide. Scientists refer to this
phenomenon as a carbon sink - a place like a forest, ocean or
other system that absorbs climate warming CO2.
"Historically about 50 percent of the carbon that is
released from the burning of fossil fuels has been taken up
by terrestrial systems and oceans, allowing only about half
of what we burn for fossil fuels to accumulate in the atmosphere,"
Werner Kurz, co-author of a study of the beetle's impact in
the journal Nature, told The Canadian Press.
"This impact converted the forest from a small net carbon
sink to a large net carbon source both during and immediately
after the outbreak," the researchers wrote, according
to Reuters.
In fact, it is global climate change that is causing the
problem in the first place, according to the researchers.
Milder winters have allowed the pine beetle to spread northward
and to higher elevations. It takes five days of extremely
cold temperatures of about minus 30 degrees Fahrenheit to
kill the beetles. Recent winters have been mild.
Future impact
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The loss of trees from a beetle infestation releases as
much carbon as a forest fire. |
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The scientists created
a computer model to estimate the damage that the beetles could
do, as well as measure their future negative impact on Canadian
energy-saving efforts to reduce carbon emissions. Reducing emissions
is a requirement of participants in the United Nations Kyoto
climate protocol, which Canada signed.
"Here we estimate that the cumulative impact of the
beetle outbreak in the affected region during 2000 to 2020
will be 270 megatonnes of carbon," the scientists wrote
in their study.
Human activity in Canada released the equivalent of 747 megatons
of carbon dioxide into the atmosphere in 2005.
In contrast, a healthy forest without the beetle blight but
with a normal amount of tree logging acts as a slight carbon
sink.
The impact of the beetles is similar to a forest fire. But,
according to the scientists, the beetles in their worst year
of infestation released more than 50 percent more carbon than
the region's worst recent fire in 2003, Nature News reports.
Possible solutions
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Pine beetles will eventually destroy their own habitat
by destroying all the largest pine trees. |
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The Canadian government
is considering possible solutions, including removing the impacted
trees before they rot and release more carbon dioxide. This
solution is supported by the logging industry, although the
wood is tainted blue by a fungus carried by the beetles and
must be sold at a cheaper price than untainted lumber.
But other scientists, such as Art Fredeen of the University
of Northern British Columbia, believe that salvage logging
disturbs plant life on the forest floor, further increasing
carbon emissions.
"You have all of the shrubs, the moss, lichen; you have
a lot of photosynthetic surface that's unperturbed by the
mountain pine beetle," Fredeen told Nature News. "When
you clear cut, of course, all of that is removed."
Another solution is planting more trees.
"We're upping our tree-planting program. And it's why
we're actually moving to a net-zero deforestation strategy
in British Columbia," B.C. Premier Gordon Campbell said.
Although Canada will have to deal with the impact of a smaller
carbon sink for decades to come, the worst may be over. The
pine beetle can only reproduce in the largest trees, and soon
90 percent of those will be gone.
"The beetle will eat itself out of house and home and
the population will eventually collapse," Kurz said.
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This [teen] is an immigrant from Mexico, and he works long hours at a local farm milking dairy cows, five hours per milking, twice a day.
