The forests are dead and dying all over North America, with billions of trees killed by the mountain pine beetle since 2000. Horrific as the sight of our forests turning brown has been, it could have been worse. A new study released this month in Ecology Letters by a University of Arizona team showed that the dead trees are not dumping the huge amounts of carbon dioxide into the atmosphere that previous scientists had feared.
Living plants, including trees, use carbon dioxide, removing it from the atmosphere. That’s an important job, especially now, because CO2 accounts for up to 84 percent of the greenhouse gases caused by human activities in the U.S. Those gases get their nickname because they act like a greenhouse to hold warmth, heating the planet in the now notorious process of global warming.
And, as most people agree by now, the climate change caused by the warming may have contributed to everything from the onrushing extinction of the polar bears to more powerful superstorms like last fall’s Hurricane Sandy.
David Moore, one of the lead authors of the new study, said that the researchers were concerned about how the massive die-offs of North America’s forests would affect the climate. Those billions of trees would have normally been using the carbon dioxide in their day-to-day life, leading to widespread speculation that the death of the trees could create a runaway warming effect because of the additional greenhouse gas that would no longer be removed from the atmosphere.
Instead, the soil microbes at the base of the dead trees might actually release the carbon dioxide that the trees had previously stored.
Fortunately, that isn’t what they discovered. It turned out that the dead trees hold onto the carbon dioxide much longer than scientists thought. The trees may not be removing the carbon dioxide any more, but at least they’re not dumping it all right back into the air.
The dead forests aren’t out to get us, even if the pine beetle is.
[photo courtesy US Forest Service]