Pacific Decadal Oscillation-like variability at a millennial timescale during the Holocene

Abstract

Sea surface temperatures (SSTs) in the North Pacific exert a great influence on global climate and ecosystem changes. The Pacific Decadal Oscillation (PDO) is the leading mode of decadal SST variability in the North Pacific. The PDO-like variability at a millennial timescale during the Holocene is still poorly understood. In this study, the millennial-scale PDO-like variability during the Holocene is explored using model–data comparisons. To reduce the uncertainties caused by differential age controls, this study reconstructs the Holocene PDO-like index using two types of published proxy records, including 1) east–west SST contrast in the extratropical North Pacific and 2) PDO-related precipitation anomalies in East Asia. These two reconstructions reveal coherent changes in the PDO-like pattern during the Holocene, showing positive phases at 10.4–8.5 ka BP and 3.5–3.0 ka BP, and negative phases at 8.5–3.5 ka BP and 3.0–0.2 ka BP. Climate simulations suggest that the millennial-scale PDO-like variability is predominantly controlled by orbital forcing during the Holocene, leading to a positive phase of the PDO-like regime during the early Holocene. The positive phase of the PDO-like regime between 3.5 and 3.0 ka BP was probably caused by the internal feedback of the climate system, which the climate simulations fail to capture.