Imminent climate and circulation shift in northeast Pacific Ocean could have major impact on marine resources

A climate shift is imminent in the northeast Pacific Ocean, research suggests, and may have a major impact on marine resources, particularly Pacific salmon. Scientists anticipate that the shift, driven by large‐scale changes in the Earth's atmospheric wave pattern, will become evident in the next few years. The most recent shift, characterized by a switch from cold and wet conditions to warm and dry conditions in the Pacific northwest of the United States, occurred in 1977 [e.g., Trenberth and Hurell, 1994]. The expected climate shift is suggested by studies of oscillations in ocean surface water drift and in treering records. Drift trajectories, derived from a new measure of decadal variability, showed well‐defined oscillations in the 20th century, but researchers were concerned that this decadal nature might not be as evident over a considerably longer time. Thus because of the possible rarity of the 30‐year interval since the last climate shift, treering width data was scrutinized for the western juniper for the period from 1500 to 1900 A.D.