Scientist warned an ongoing drought in Montana and other states may be part of a third mega-drought to hit the western United States in 100 years, at a national gathering of meteorologists and other weather experts, the Montana Tracker reported.
According to Julio Betancourt, a project chief at the U.S. Geological Survey Desert Laboratory in Tucson, Ariz., the region may be only about halfway through it if the current drought follows long-term patterns.
Betancourt said the West suffered through an extended severe drought in the 1930s and one of lesser magnitude during the 1950s. Data from the current drought, which he dates back to 1995, resembles that from the 1950s dry spell.
According to him, ocean conditions are similar to those 50 years ago, and temperatures in the Atlantic Ocean are rising, while those in the eastern and tropical portions of the Pacific are cooler.
Using tree-ring studies to reconstruct ocean temperature trends for the past 500 years, Betancourt said the Atlantic warming appears to last 23 years at a time, but ranges from nine to 53 years. The Pacific tends to change more quickly, and warming periods range from one to 31 years with an average of six years, according to the Montana Tracker.
Climate cycles may be interrupted by El Nino and La Nina events that can briefly alter temperature and precipitation, and Betancourt said people occasionally celebrate a drought's end too early.
The current drought follows a prolonged wet period when cooler Atlantic temperatures prevailed between 1965 and 1995, a time when the West saw more urban development and a big population increase.
"In the event of continuing drought, it remains to be seen whether or not comparable rates of growth can be sustained without renegotiating water agreements," Betancourt said.