The Pine Beetle Devours the American West

Global warming can sometimes feel like an intangible phenomenon. But if you live in the West, as I do, the evidence piles up in the stark form of dead trees. Since 2000 more than 6.5 million acres have perished in the U.S., turning forests into meadows in almost a dozen states. The culprit: the pine beetle, a fingernail-size bug that's become more voracious as the planet warms. Once a balanced part of forest life, the tree--eating insect now usually survives the winter, starts feeding earlier in the spring, and continues to plunder late into the fall. Entomologists are worried about multiple generations of beetles coexisting each season—a swarm that could wipe out enough trees to ruin land prices, the logging industry, and outdoor tourism.

Nowhere is the epidemic felt more keenly than in Colorado, where the Forest Service recently created an emergency-management team to cull dead trees from near roads and power lines, and wooded communities have drawn up evacuation plans—a hedge against the threat of tinder-dry trees catching fire. Others have taken the costly step of having their infected trees hauled away. "I've never seen anything like it," says University of Montana professor Diana Six, who has studied the die-off. "The whole ecosystem is changing."

Robbins is the author of the forthcoming book The Forgotten Forest.