Beetle Infestation Compounds Effects of Warming

In western Canada, tree-infesting beetles are flourishing due to warmer temperatures caused in part by global warming. But a new study in the journal Nature argues that these pests may also be compounding the effects of climate change by destroying the trees that suck key pollutants out of the atmosphere.

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Beetles that turn 100-year-old trees into dead, gray sticks are ripping through forests in western Canada. Many experts say the infestations are caused by warmer weather linked to global climate change. And that's not all. According to a new study, these beetle outbreaks could also end up making global warming worse.

NPR's John Nielsen has the story.

JOHN NIELSEN: When the thick, green forests that cover much of British Columbia turn red in the spring, it usually means the end is near. Werner Kurtz of the Canadian Forest Service says that's because the redness is a sure sign that these forests have been overrun by tiny, black pine beetles that carry a deadly fungus.

Mr. BURNER KURTZ (Canadian Forest Service): And within a few months, the foliage falls off, and so you basically go from a sea of green to a sea of red to a sea of gray over very large areas.

NIELSEN: Pine beetles are nothing new in Canada, but Kurtz says they've never been as active or as destructive as they are right now. Since 1997, he says they've killed at least 30 million acres worth of jack and lodgepole pine trees. That's an area the size of Pennsylvania.

Mr. KURTZ: This current outbreak is at least one order of magnitude greater than anything recorded in history. And we think that it is, for a variety of reasons, probably the largest outbreak that has ever occurred.

NIELSEN: Kurtz says this gigantic infestation is destroying logging towns and driving tourists away. And there's another problem. If the beetles keep on spreading, they could ruin Canada's plans to slash emissions of carbon dioxide, the most important global warming gas.

Kurtz says it's easy to understand that particular connection if you remember that live trees suck lots of carbon dioxide out of the atmosphere. That means Canada's giant forests can take up staggering amounts of CO2, but only while they're alive.

Mr. KURTZ: And if these forests get disturbed and trees are killed, and as the tree decomposes, carbon dioxide is released back into the atmosphere.

NIELSEN: Recently, Kurtz led a team that tried to figure out how many trees those beetles would end up killing in the end and how much CO2 the dead trees would release. In the current issue of the journal Nature, he says computer models show that the infestations would be over by the year 2020 at the latest, but by then the rotting trees will have released 270 megatons of carbon dioxide.

Kurtz says that is disturbing. First of all, it just so happens that 270 megatons is exactly the amount of greenhouse gas that Canada had planned to cut by the year 2012, which means that the beetles have just made that task much harder. Secondly, it means that Canada's forests are about to become a source of carbon dioxide and not a place where it gets stored away. Basically, says Kurtz, it's a double whammy.

Mr. KURTZ: The warming is enhancing the beetle, and the beetle in turn -through its impact on the greenhouse gases balance of the forests - is enhancing the warming.

NIELSEN: This is one of the first attempts to understand how insects might make global warming worse. And ecologist Jeff Hickey(ph) at the University of Idaho says he hopes it won't be the last. Hickey says this study makes him wonder whether other insect infestations are compounding global warming problems as well.

Mr. JEFF HICKEY (Ecologist, University of Idaho): In eastern Canada, there's extensive outbreaks of spruce budworm. In (unintelligible) Russia, there's outbreaks of a moth that appear to kill many trees, too. This is not a unique situation in a global sense, and therefore the global models need to account for this kind of biotic disturbance.

NIELSEN: Especially in countries that are counting on their forests to suck a lot of carbon dioxide out of the atmosphere.

John Nielsen, NPR News, Washington.

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