Mountain Pine Beetle Invasion in Canada Poses Global Warming Threat
Image courtesy of D&J; Huber via flickr
A festering problem Lloyd reported on last year -- the invasion of British Columbia's forests by voracious mountain pine beetles -- has taken a drastic turn for the worse, according to a new study published in the journal Nature. Werner Kurz of Natural Resources Canada found that the beetles are turning large tracts of forests into carbon sources -- rather than sinks -- aggravating the onset of global warming.Kurz and his colleagues modeled the carbon budget for 374,000 square kilometers of pine forest, estimating that close to 270 megatonnes of carbon would disappear from the area between 2000 and 2020 -- much of it lost as carbon dioxide emitted by dying trees. The impact of the pine beetles' blight was determined to be worse than that of the 2003 forest fires: causing a pine forest -- considered a slight carbon sink in their model, when untouched -- to release 50% more carbon than when effected by a fire.
While most previous models had only considered forests' beneficial effects on the climate, Kurz cautioned that the negative impacts -- their ability to also release massive amounts of carbon dioxide -- also needed to be taken into account. Reforestation efforts in the last 2 decades have not been able to keep pace with the beetles' destruction, and the impact of logging risks making a bad situation worse.
B.C. officials have encouraged the practice of salvage logging as a mitigation strategy, but Kurz notes that this may actually lead to more emissions being released; logging removes all the natural forest-floor vegetation, eliminating more potential carbon sinks. Furthermore, most of the wood retrieved from the dying trees is of dubious quality: A fungus carried by the beetles, known as a "blue fungus," discolors the wood, reducing its value. An alternative strategy, burning the trees for energy, would also aggravate the problem.
In the end, what will eventually stop the beetles' infestation is their own voracious appetite. The large trees they feed on and use for reproductive purposes will soon all be gone. "The beetle will eat itself out of house and home, and the population will eventually collapse," Kurz said.
But, as DeSmogBlog's Mitchell Anderson warns, the risk is that the beetles, having already crossed over the Rocky Mountains, could threaten Canada's entire boreal forest. The results, he glibly notes, wouldn't be pretty:
If the same cycle of devastation and carbon release occurs, we will be looking at much bigger eventual release of carbon dioxide than one billion tonnes.
Dr.. Kurz's research demonstrates the dangerous complexities of playing with the thermostat of the planet. This new source of atmospheric carbon from by decomposing trees is an excellent example of what scientists pedantically call "positive feedback loops ".
The rest of us might better describe these unplanned accelerations of climate change as the "holy crap factor ".