Synchronous multi-decadal climate variability of the whole Pacific areas revealed in tree rings since 1567

Keyan Fang,Edward Cook,Yan Zhao,Tinghai Ou,Zhengtang Guo,Deliang Chen

doi:10.1088/1748-9326/aa9f74

Abstract

Oceanic and atmospheric patterns play a crucial role in modulating climate variability from interannual to multi-decadal timescales by causing large-scale co-varying climate changes. The brevity of the existing instrumental records hinders the ability to recognize climate patterns before the industrial era, which can be alleviated using proxies. Unfortunately, proxy based reconstructions of oceanic and atmospheric modes of the past millennia often have modest agreements with each other before the instrumental period, raising questions about the robustness of the reconstructions. To ensure the stability of climate signals in proxy data through time, we first identified tree-ring datasets from distant regions containing coherent variations in Asia and North America, and then interpreted their climate information. We found that the multi-decadal covarying climate patterns of the middle and high latitudinal regions around the northern Pacific Ocean agreed quite well with the climate reconstructions of the tropical and southern Pacific areas. This indicates a synchronous variability at the multi-decadal timescale of the past 430 years for the entire Pacific Ocean. This pattern is closely linked to the dominant mode of the Pacific sea surface temperature (SST) after removing the warming trend. This Pacific multi-decadal SST variability resembles the Interdecadal Pacific Oscillation.

Highlights

Natural and anthropogenic forcings often indirectly influence interannual (f < 0.1) and interdecadal (0.1 < f < 0.01) climate variations by modulating oceanic and atmospheric oscillations [1–4]
We found that the multi-decadal covarying climate patterns of the middle and high latitudinal regions around the northern Pacific Ocean agreed quite well with the climate reconstructions of the tropical and southern Pacific areas
The mean of these tree-ring chronologies with coherent variations are expected to reflect the dominate climate pattern of the areas surrounding the northern Pacific Ocean over the past 430 years. This mean time series shows significant periodicities centered at ∼60 years, which agrees with previous findings of the presence of dominant multi-decadal periodicities at 50–70 years for the northern Pacific Ocean [2]

Summary

Introduction

Natural and anthropogenic forcings often indirectly influence interannual (f < 0.1) and interdecadal (0.1 < f < 0.01) climate variations by modulating oceanic and atmospheric oscillations [1–4]. Instrumental records are limited to the past several decades e.g. after the 1950s, in most regions of Asia [11], which hinders our ability to comprehend the evolution of the oceanic and atmospheric oscillations and their linkages with largescale climate anomalies [12–15]. Proxy data, such as tree rings, have been widely used to reconstruct oceanic and atmospheric oscillations over the past millennia [5–7, 12, 14, 15]. Unlike the relatively coherent variations among different temperature reconstructions, tree-ring based reconstructions of the same climatic oscillations using proxy data from different regions often show limited similarities before the instrumental period [1, 14], 70 N

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Conclusion