By William deBuys
[…]
Fire is only one cause of forest death. Heat alone can also
do in a stand of trees.According
to the Texas Forest Service, between 2% and 10% of all the trees in
Texas, perhaps half-a-billion or so, died in last year’s heat wave, primarily
from heat and desiccation. Whether you know it or not, those are staggering
figures.
Insects, too, stand ready to play an ever-greater role in
this onrushing disaster. Warm temperatures lengthen the growing season, and
with extra weeks to reproduce, a population of bark beetles may spawn
additional generations over the course of a hot summer, boosting the number of
their kin that that make it to winter. Then, if the winter is warm, more larvae
survive to spring, releasing ever-larger swarms to reproduce again. For as long
as winters remain mild, summers long, and trees vulnerable, the beetles’
numbers will continue to grow, ultimately overwhelming the defenses of even
healthy trees.
We now see this throughout the Rockies. A mountain pine
beetle epidemic has decimated lodgepole pine stands from Colorado to Canada.
About five million acres of Colorado’s best scenery has turned red with dead
needles, a blow to tourism as well as the environment. The losses are far
greater in British Columbia, where beetles have laid waste to more than 33
million forest acres, killing a volume of trees three times greater than
Canada’s annual timber harvest.
Foresters there call the beetle irruption “the largest known
insect infestation in North American history,” and they point to even more
chilling possibilities. Until recently, the frigid climate of the Canadian
Rockies prevented beetles from crossing the Continental Divide to the interior
where they were, until recently, unknown. Unfortunately, warming temperatures
have enabled the beetles to top the passes of the Peace River country and penetrate northern
Alberta. Now a continent of jack pines lies before them, a boreal smorgasbord
3,000 miles long. If the beetles adapt effectively to their new hosts, the path
is clear for them to chew their way eastward virtually to the Atlantic and to
generate transformative ecological effects on a gigantic scale.
The mainstream media, prodded by recent drought declarations
and other news, seem finally to be awakening to the severity of these
prospects. Certainly, we should be grateful. Nevertheless, it seems a tad
anticlimactic when Sam Champion, ABC News weather editor, says with this-just-in urgency to anchor
Diane Sawyer, “If you want my opinion, Diane, now’s the time we start limiting
manmade greenhouse gases.”
One might ask, “Why now, Sam?” Why not last year, or a
decade ago, or several decades back? The news now overwhelming the West is, in
truth, old news. We saw the changes coming. There should be no surprise that
they have arrived.
It’s never too late to take action, but now, even if all
greenhouse gas emissions were halted immediately, Earth’s climate would
continue warming for at least another generation. Even if we surprise ourselves
and do all the right things, the forest fires, the insect outbreaks, the
heat-driven die-offs, and other sweeping transformations of the American West
and the planet will continue.
[…]
In the meantime, forget about any sylvan dreams you might
have had: this is no time to build your house in the trees.
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