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Recent unprecedented change of Pacific decadal variability shows a fingerprint of anthropogenic forcing
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  • Weiyi Sun,
  • Bin Wang,
  • Jian Liu,
  • Yifei Dai
Weiyi Sun
Key Laboratory for Virtual Geographic Environment, Ministry of Education; State Key Laboratory Cultivation Base of Geographical Environment Evolution of Jiangsu Province; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application;School of Geography Science, Nanjing Normal University, Nanjing 210023, China
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Bin Wang
Department of Atmospheric Sciences and International Pacific Research Center,University of Hawaii
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Jian Liu
Nanjing Normal University

Corresponding Author:[email protected]

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Yifei Dai
Nanjing University of Information Science and Technology
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Abstract

How the Pacific Decadal Variability (PDV) would change under a warming world remains an issue of scientific debate and societal concern. Here we show that the PDV has been experiencing an unprecedented change in the last two decades. The PDV has amplified along the west coast of North America and equatorial central Pacific while weakened over the South Pacific and Kuroshio-Oyashio Extension (KOE) region. Examination of 33 CMIP6 models’ ensemble mean projection reveals that anthropogenic radiative forcing may weaken the PDV variability in the South Pacific and KOE region, suggesting part of the observed change may be attributed to anthropogenic forcing. However, the recently increased decadal variability over the western North American coast and equatorial central Pacific may be part of the internal variability arising from increased coupling between the positive Pacific Decadal Oscillation (PDO) and negative North Pacific Gyre Oscillation (NPGO).