May 23, 2012
Those Southwest fires were weirder than normal forest fires.
Looking at trees, scientists have decided the fires ravaging that region are "unusual." The scars indicate fire unprecedented in that area's history -- even when the climate was hotter and dryer than it is today. "Many of our modern forests in central Arizona and New Mexico haven't had a fire of any kind on them in 130 or 140 years," explains researcher Christopher Roose. "That's very different from the records of the ancient forests. The longest they would have gone without fires was 40 or 50 years, and even that length of time would have been exceptional." And, yup, humans are to blame. "The U.S. would not be experiencing massive large-canopy-killing crown fires today if human activities had not begun to suppress the low-severity surface fires that were so common more than a century ago," he continues.