By Philip Mote, University of Washington

Members of the Climate Impacts Group (CIG) at the University of Washington in Seattle have been actively engaged in research on climate variability, climate change, and impacts on the Pacific Northwest region. Studies focus on climate-sensitive sectors like water supply, salmon populations, forest health, and coastal development. This research will provide an important contribution to the region's assessment

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At its annual meeting last June, the CIG presented research results before an audience that included both stakeholders and scientists. Results concentrated on past climate variability in the Pacific Northwest, its relationship to two cyclical "climate drivers" (ENSO, the El Nino-Southern Oscillation, and PDO, the Pacific Decadal Oscillation), and its impacts on biological and hydrological systems. The PDO, like ENSO, is a natural variation of sea surface temperature in the Pacific, but unlike ENSO it characterizes variations in sea surface temperature in the North (as opposed to equatorial) Pacific. The PDO also has a much longer time scale, with positive (warmer) phases from 1925 to 1945 and after 1977, and negative (cooler) phases from 1900 to 1925 and from 1945 to 1977. The CIG research results included the following:

• Analysis of tree ring data shows that 1925-1945 (a positive phase of the PDO) was the warmest and driest period in the last 250 years.
• Rivers flood more commonly during the cold phase of ENSO and the negative phase of the PDO.
• Juvenile coho salmon (at least those entering the ocean along the outer coast of the PNW) survive better in colder water, conditions more common in the negative phases of ENSO and PDO.
• Using past associations between Columbia River flow and different phases of ENSO and PDO, it may be possible to predict Columbia River flow for an entire water year, from October to September.
• Analysis of Columbia River flow indicates that the phase of PDO may have changed recently from positive to negative. Wet years like 1996-97 are very unusual in a positive PDO. (The PDO has been in its positive phase since 1977.)
• Area burned by forest fires (in the years before fire suppression efforts became widespread) was greatest in the positive phase of PDO.
• Even extremely accurate forecasts of the number of salmon returning may have little economic value in part because of the flexibility of annual quota-setting procedures and in part because of the spatial and temporal scales on which forecasts would be needed by decision-makers.

As the CIG heads into its fourth year, it is developing formal links with a group at Washington State University, which will study potential effects of climate change on soils and crops; with forest hydrologists at Oregon State University; and possibly with other research groups. Informal links have also been developed with a regional modeling and impact-assessment group in Sweden, where the climate and the economic base are similar to the Pacific Northwest.

For more information, contact:

Phil Mote, Unversity of Washington, Box 354235; Seattle, WA, 98195; (206) 616-5346; phlip@atmos.washington.edu; or see the CIG web site at http://jisao.washington.edu/