A 900 year stable isotope record of interdecadal and centennial change from the California Current

This paper describes the development of a high-resolution record of interdecadal and centennial variability of ocean climate of the California Current from continuous 5 year sampling intervals based on varve counts from Santa Barbara Basin sediments. We show the importance of the choice of species and size fraction as well as the practice of making multiple measurements per interval to obtain a clear environmental signal capable of resolving interdecadal change. Changes in temperature and salinity from oceanographic surveys of the past 50 years indicate that thermal variability dominates the delta O-18 signal. A delta O-18 record from Neogloboquadrina dutertrei spanning 1030-1905 A.D. contains interdecadal thermal fluctuations within the upper thermocline that are centered around periods of roughly 55, 70, and 90 years. The interdecadal changes comprise the major share of total variability compared to a low-amplitude mode of underlying multicentennial variability corresponding to the Medieval Warm Period and the Little Ice Age.