Klamath Basin Chapter, 
Native Plant Society of Oregon

Tree Rings Yield Clues About Historic Drought Cycles

  • April 24, 2014
  • 7:00 PM
  • Ross Ragland Theater Cultural Center
Old CedarResearch based on examination of tree rings in the Klamath Basin reveals very long droughts have occurred over the past thousand years, according to a recent report.

Scientists who conducted the research will discuss their findings in a presentation scheduled for 7 p.m. Thursday, April 24, at a meeting of the Klamath MalovitchCounty Historical Society.

The presentation will be given in the Ross Ragland Theater Cultural Center, and is open to the public.

Readings from modern weather instruments can researcherreveal weather patterns that vary from year to year or decade to decade, but only for the past century or so. Tree rings, however, can provide clues to much longer-term climate variations, said Steven Malevich, a doctoral student in geosciences at the University of Arizona.

“Droughts in the 1920s and ’30s were of considerable duration and severity,” Malevich said. “But some of the longest and most severe droughts occurred prior to the 20th century, from the 11th to the 13th centuries – far beyond the reach of weather instrument records.”

Malevich will report on his findings along with a co-author of the study, Connie Woodhouse, professor in the School of Geography and Development and the Laboratory of Tree-Ring Research at the University of Arizona.

Their study, the first to establish a thousand-year record of the climate for the Klamath Basin through tree ring analysis, indicates dry periods lasting up to 50 years have occurred in the distant past.

Malevich and Woodhouse studied core samples collected from dozens of trees in the Klamath Basin, and compared the results with similar samples collected in other research projects around the West.

According to their report, the comparison reveals that long-term climate patterns can vary from one region to the next, depending on the position of the jet stream.

“The drought events of the past decade have had economic and political impact,” the report reads. “If sustained dry events such as those which appear in the early 20th century, 1000s or 1100s were to be experienced today, it would prove a challenge to those who manage or draw on Klamath basin water supplies.”

For more information about the April 24 program, contact the Klamath County Museum at (541) 883-4208.
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