Oregon Public Broadcasting

A remarkable piece of scientific detective work has constructed a 6,000 year climate history of the Pacific Northwest.  The record reveals a pattern of drought cycles and wet cycles.

The study points to a more arid future for the Northwest.

A remarkable piece of scientific detective work has constructed a 6,000 year climate history of the Pacific Northwest. The record reveals a pattern of drought cycles and wet cycles.

Researchers drilled into the sediments at the bottom of Castor Lake near Omak, Washington. 

It's a telltale lake because with no river running out of it rainfall and evaporation rule there. 

Study co-author Mark Abbott of the University of Pittsburgh says wet years and dry years cause subtle changes in the water chemistry.

Mark Abbott: "The limestone actually makes an archive in the sediments.  It's kind of like the pages in a book, of a history book."

The chapter about the 20th century in that history book reveals abnormal conditions in the Northwest. 

Mark Abbott: "That was probably one of the wettest periods in the last 6000 years."

It was the same period when governments wrote a lot of our Western water laws too. 

Now we've entered what Abbott says is a more typical drier phase. 

His assessment correlates with run-off records kept by the Bonneville Power Administration. 

Nine of the last ten water years have been below average.

Mark Abbott: "Of course, that will affect all kinds of things from hydropower, to fish populations, to drinking water resources."

Researchers from six universities collaborated on this study just published in the Proceedings of the National Academy of Sciences.  The National Science Foundation paid for the research.

Proceedings of the National Academy of Sciences