Pacific decadal variability over the last 2000 years and implications for climatic risk

The Interdecadal Pacific Oscillation (IPO), an index defining decadal climate variability throughout the Pacific, is generally assumed to have positive and negative phases lasting 20–30 years. This study presents a 2000-year reconstruction of the IPO using Antarctic ice core data, revealing that negative phases are short (7 ± 5 years) and infrequent (10% of the time), occurring within a predominantly neutral-positive state lasting decades (61 ± 56 years). This challenges the current understanding of Pacific Basin climate risk, highlighting the over-representation of negative phases in post-1900 observations. The implications for eastern Australia, where drought risk is elevated during neutral-positive phases, are demonstrated, emphasizing the need to re-evaluate climate risk for all IPO-affected regions. The research also emphasizes the need to prioritize the study of the initiation and future frequency of negative phases.

Tessa R. Vance, Anthony S. Kiem, Lenneke M. Jong, Jason L. Roberts, Christopher T. Plummer, Andrew D. Moy, Mark A. J. Curran, Tas D. van Ommen