Core samples from ancient living and dead bristlecone pines in the San Juan Mountains of Colorado show signs of extreme drought in the second century that matches or exceeds the better-known droughts of the medieval period, University of Arizona researchers said.
The researchers concluded the second century drought was regional, extending from what is now southern New Mexico north and west into present-day Idaho, the Los Angeles Times reported Thursday.
Some scientists had considered the severe Western U.S. droughts that occurred between 900 and 1400 unique, paleoclimatologist Connie Woodhouse said.
The new tree ring record indicates they weren't, she said, and they could occur again.
"There is no good reason that we shouldn't expect to have those," Woodhouse said.