Andrew Bernier/KJZZ

Wood from a tree that has been infested by bark beetles.

Pine beetles destroyed forests in the Sierra Nevada in just a few years, and researchers say they may never return to pre-drought levels.

Their findings may hold true in high-country regions throughout the Southwest.

Climate change has paved the way for the insects, because drought makes ponderosa pines vulnerable to their attack.

Researchers at Los Alamos National Laboratory in New Mexico say that the loss of trees, which store carbon, can make global warming worse.

And although the study took place in California, bark beetles have ravaged forests throughout the West.

"So we have large populations of ponderosa pine in Arizona, here in New Mexico and Colorado, and we see a similar pattern in many forests across the United States," said Zachary Robbins, a researcher at Los Alamos.

He says that dense growth in the Western forests has also contributed to the problem.