California's Decadal Records

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Science  26 Jan 2001:
Vol. 291, Issue 5504, pp. 555
DOI: 10.1126/science.291.5504.555d

Measurements of Pacific Ocean sea surface temperatures have revealed a pattern of decadal variability called the Pacific Decadal Oscillation (PDO). This variability has a strong influence on North American climate and appears to be related to the El Niño-Southern Oscillation. Unfortunately, the instrumental record extends back only to about 1900, which is too short for assessing whether the PDO is a persistent or regular feature of climate.

Biondi et al. have developed a tree-ring chronology from Southern and Baja California, an area well suited to investigate changes in the eastern Pacific Ocean, that they use as a proxy for the PDO for the past nearly 350 years. The major features of the tree growth record are closely related to those of the PDO index for the past 75 years, and the rings display a pattern of decadal variability, stronger during some periods than during others, throughout the interval they studied. Their PDO reconstruction shows that the largest shifts in regional climate occurred around 1750, 1905, and 1947, and that three of the four most significant decadal climate transitions of the past 330 years occurred in the twentieth century. — HJS

J. Clim.14, 5 (2001).

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