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

Abstract

a b s t r a c tPacific 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 w8000 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 w4200 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 w4000 cal BP off southern California, w3400 cal BP off northern California, and by w2000 cal BP in southwestern Yukon. A progressively northward migration of the ENSO teleconnection during the late Holocene is proposed.

Paired oxygen isotope records reveal modern North American atmospheric dynamics during the Holocene

“…We suggest that the inversely correlated component of isotopic change in the western and eastern sites may reflect long-term variability of the mean state of PNA through the Holocene based on the documented association of anti-phase precipitation isotopic variation in these regions with PNA. During the MH, relatively low d 18 ARTICLE across North America [19][20][21] , and corresponds temporally with the 4.2-3.9 kyr before present (BP) abrupt climate event documented globally 22 . Our result is supported by independent proxy evidence from a range of sites across the continent.…”

“…Paired values from the re-sampled time series are significantly anticorrelated for each archive (r ¼ À 0.55, Po0.001 and n eff ¼ 25 for speleothem and r ¼ À 0.13, Po0.1 and n eff ¼ 11 for lake sediment, see Methods). Within each region, d 18 O values of different archives also exhibit statistically significant but positive correlations (r ¼ 0.18, Po0.005 and n eff ¼ 15 for the western records, re-sampled at a common 22-year resolution, and r ¼ 0.72, Po0.001 and n eff ¼ 34 for the east at a 47-year resolution). Data from both lake sediments and speleothems show significant (Po0.0001) secular change throughout the period of record, with opposing trends for records derived from the western (increasing with time) and eastern (decreasing with time) sites ( Fig.…”

“…1) and eastern (Buckeye Creek Cave (BCC) speleothem 15 and Lake Grinnell sediment 16 ; sites 1 and 3) regions of isotope/PNA correlation. Each time series consists of carbonate d 18 O measurements that were re-sampled to a common sampling resolution (47 years for speleothems, 35 years for lake sediments, see Methods) and represents local variation in mid-Holocene (MH) to late-Holocene (LH) precipitation d 18 O values, likely overprinted by variation in local temperature, humidity and soil or lake water balance. Our results demonstrate anti-phase variability in the eastern and western regions, consistent with the expected expression of variation in the PNA pattern, over both millennial and centennial timescales.…”

Variability of marine biological productivity in the northeastern Pacific over the past millennium

“…This indicates an onshore movement of nutrient-poor subtropical waters and a decline in upwelling off California, except in the Santa Barbara Basin, where upwelling was more intense in spring (Barron and Anderson 2011). The planktonic foraminiferal assemblages experienced important changes over the past 2000 years in Santa Barbara Basin (Fisler and Hendy 2008) and Soledad Basin (Wilsbacher 2007).…”

Filling a Geographical Gap: New Paleoecological Reconstructions From the Desert Southwest, USA

“…However, various modes of ENSO are associated with different impacts on western NA hydroclimate (Ashok et al, 2007), and teleconnections can vary on decadal-to-centennial time scales (Gershunov and Barnett, 1998b), suggesting that southwest hydroclimate does not always respond to ENSO variability in a linear manner based on our modern understanding of southwest hydroclimate and ENSO correlations (Heyer et al, 2017). However, despite teleconnection variability (Gershunov and Barnett, 1998b), dipole variability (Wise, 2010) and different modes of ENSO (Ashok et al, 2007), paleo-sedimentary records suggest teleconnections between ENSO and southwest climate are similar to those observed in the modern record, and have persisted at century-millennial time scales (Barron and Anderson, 2010;Antinao and McDonald, 2013;Kirby et al, 2014;Hart et al, 2015). Further, paleoecological records have revealed the ENSO phenomenon is correlated with fire regimes of the southwest (Swetnam and .…”