Climate feedback: Beetle tree kill releases more carbon than fires

[RedEarth]

“He that troubleth his own house shall inherit the wind.” A Biblical proverb for our times, it turns out….

The bark beetle is devastating North American trees (see “Climate-Driven Pest Devours N. American Forests“).

Global warming has created a perfect climate for these beetles — Milder winters since 1994 have reduced the winter death rate of beetle larvae in Wyoming from 80% per year to under 10%, and hotter, drier summers have made trees weaker, less able to fight off beetles.

New reseach published in the journal Nature, “Mountain pine beetle and forest carbon feedback to climate change,” (subs. req’d, abstract reprinted below), quantifies the current and future impact just from the beetle’s warming-driven devastation in British Columbia:

… the cumulative impact of the beetle outbreak in the affected region during 2000–2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m-2 yr-1 on average over 374,000 km2 of forest). This impact converted the forest from a small net carbon sink to a large net carbon source.

No wonder the carbon sinks are saturating faster than we thought (see here) — unmodeled impacts of climate change are destroying them:

Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon, and such impacts should be accounted for in large-scale modelling analyses.

Any “good news” here? Only if you like very dark irony. The accompanying news story (here, subs. req’d) notes:

Even if climate change brings further warm winters to the region, however, experts think this infestation has probably peaked. Mountain pine beetles can only reproduce in the largest trees, which were abundant thanks to a growth spurt after wildfires raged across western North America 80 to 140 years ago. Soon 80 to 90% of those large trees will be gone, Kurz says. “The beetle will eat itself out of house and home, and the population will eventually collapse.”

Hmm. “Eat itself out of house and home.“ Does the bark beetle sound like any other species we know? Finally, the species formerly known as homo sapiens sapiens is no longer alone in its self-destructive quest to destroy its habitat. Inhert the wind, indeed.

http://climateprogress.org/2008/04/25/nature-on-stunning-new-climate-feedback-beetle-tree-kill-releases-more-carbon-than-fires/#more-2728

[mike_c]

1. the climate connection is almost incidental, although it's providing...

...an undeniably important driver in dark beetle outbreaks today. Still, far and away the most important factor in beetle outbreaks has been fire suppression during the last century and consequent overstocking of conifer forests. In the southeastern coastal plain replacement of longleaf pine with loblolly has exacerbated the problem where it has occurred, but this is also tied to the suppression of natural fire cycles.