Enhanced Late Holocene ENSO/PDO expression along the margins of the eastern North Pacific

Abstract

Pacific climate is known to have varied during the Holocene, but spatial patterns remain poorly defined. This paper compiles terrestrial and marine proxy data from sites along the northeastern Pacific margins and proposes that they indicate 1) suppressed ENSO conditions during the middle Holocene between ∼8000 and 4000 cal BP with a North Pacific that generally resembled a La Niña-like or more negative PDO phase and 2) a climate transition between ∼4200 and 3000 cal BP that appears to be the teleconnected expression to a more modern-like ENSO Pacific. Compared to modern day conditions, the compiled data suggest that during the middle Holocene, the Aleutian Low was generally weaker during the winter and/or located more to the west, while the North Pacific High was stronger during the summer and located more to the north. Coastal upwelling off California was more enhanced during the summer and fall but suppressed during the spring. Oregon and California sea surface temperatures (SSTs) were cooler. The Santa Barbara Basin had an anomalous record, suggesting warmer SSTs. Late Holocene records indicate a more variable, El Niño-like, and more positive PDO Pacific. The Aleutian Low became more intensified during the winter and/or located more to the east. The North Pacific High became weaker and/or displaced more to the south. Coastal upwelling off California intensified during the spring but decreased during the fall. Oregon and California SSTs became warmer, recording the shoreward migration of sub-tropical gyre waters during the fall, while spring upwelling (cooler SST) increased in the Santa Barbara Basin. The high-resolution proxy records indicate enhanced ENSO and PDO variability after ∼4000 cal BP off southern California, ∼3400 cal BP off northern California, and by ∼2000 cal BP in southwestern Yukon. A progressively northward migration of the ENSO teleconnection during the late Holocene is proposed.