An alkenone (U37K′) quasi-annual sea surface temperature record (A.D. 1440 to 1940) using varved sediments from the Santa Barbara Basin

Analyses for C37 alkenones (U37K′) and total organic carbon (TOC) in a varved core from the depocenter of the Santa Barbara Basin (34°13.5′N, 120°01′W, 590 m water depth) have been made on an approximately 1–2 year basis from A.D. 1440 to 1940. The U37K′-based sea surface temperature (SST) record oscillates around 15.5°C with an amplitude of less than 3°C at approximately interannual, decadal, and centennial frequencies. Historical El Niño/Southern Oscillation (ENSO) events are matched only partially by warmer U37K′ SSTs. Three records: our SST, a published Pacific coral δ18O, and a published tree-ring temperature anomaly from the California valleys, show no evidence of colder temperatures during the Little Ice Age (ca. 1500 to 1840 A.D.). Significantly, there is a strong centennial-scale cyclicity in the U37K′ SST record which approaches 1°C in amplitude. TOC burial and alkenone fluxes are largely controlled by sedimentation rate as expressed in varve thickness.