Development of the California Current during the past 12,000 yr based on diatoms and silicoflagellates

Detailed diatom and silicoflagellates records in three cores from the offshore region of southern Oregon to central California reveal the evolution of the northern part of the California Current during the past 12,000 yr. The early Holocene, prior to similar to 9 ka, was characterized by relatively warm sea surface temperatures (SST), owing to enhanced northerly flow of the subtropical waters comparable to the modem Davidson Current. Progressive strengthening of the North Pacific High lead to intensification of the southward flow of the California Current at similar to 8 ka, resulting in increased coastal upwelling and relatively cooler SST which persisted until similar to 5 ka. Reduced southward flow of the California Current between similar to 4.8 ka and 3.6 ka may have been responsible for a period of decreased upwelling. Modem seasonal oceanographic cycles, as evidenced by increased spring-early summer coastal upwelling and warming of early fall SST evolved between 3.5 and 3.2 ka. Widespread occurrence of paleoceanographic and paleoclimatic change between similar to 3.5-3.0 ka along the eastern margins of the North Pacific was likely a response to increasing ENSO variability in the tropical Pacific. Published by Elsevier B.V.