Erosion, caused in large part by unusually severe storms, has damaged beaches and property in recent years along the Pacific coast of the United States. In the Pacific Northwest (Oregon and Washington), four storms were experienced during the 1998–1999 La Niña winter that produced wave heights which exceeded what had been projected as the 100-year extreme event. This occurrence raises questions about the effects of climate controls— such as El Niños and La Ni˜nas—on wave conditions in the North Pacific, and whether there has been a progressive increase in wave heights during recent decades, much as has been found in the North Atlantic.
In the North Atlantic, researchers have documented from a long-term record of wave measurements west of Lands End, England, that wave heights have increased progressively since the late 1960s [Carter and Draper, 1988; Bacon and Carter, 1991; Kushnir et al., 1997; Gulev and Hasse, 1999]. Previous to our study, no attempt had been made to examine whether such trends exist in the North Pacific. This is now possible, thanks to more than a quarter-century of ocean buoy measurements of daily wave conditions throughout the eastern North Pacific.