Pacific warm pool subsurface heat sequestration modulated Walker circulation and ENSO activity during the Holocene

Haowen Dang; Zhimin Jian; Yue Wang; Mahyar Mohtadi; Yair Rosenthal; Liming Ye; Franck Bassinot; Wolfgang Kuhnt

doi:10.1126/sciadv.abc0402

Pacific warm pool subsurface heat sequestration modulated Walker circulation and ENSO activity during the Holocene

Sci Adv. 2020 Oct 14;6(42):eabc0402. doi: 10.1126/sciadv.abc0402. Print 2020 Oct.

Authors

Haowen Dang¹, Zhimin Jian², Yue Wang¹, Mahyar Mohtadi³, Yair Rosenthal⁴, Liming Ye⁵, Franck Bassinot⁶, Wolfgang Kuhnt⁷

Affiliations

¹ State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China.
² State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China. jian@tongji.edu.cn.
³ MARUM-Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany.
⁴ Department of Marine and Coastal Science and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
⁵ Key Laboratory of Submarine Geosciences, Second Institute of Oceanography, Ministry of Natural Resources of China, Hangzhou 310012, China.
⁶ Laboratoire des Sciences du Climat et de l'Environnement/IPSL, CEA-CNRS-UVSQ, University Paris-Saclay, 91198 Gif-sur-Yvette, France.
⁷ Institute of Geosciences, Christian-Albrechts-University, D-24118 Kiel, Germany.

Abstract

Dynamics driving the El Niño-Southern Oscillation (ENSO) over longer-than-interannual time scales are poorly understood. Here, we compile thermocline temperature records of the Indo-Pacific warm pool over the past 25,000 years, which reveal a major warming in the Early Holocene and a secondary warming in the Middle Holocene. We suggest that the first thermocline warming corresponds to heat transport of southern Pacific shallow overturning circulation driven by June (austral winter) insolation maximum. The second thermocline warming follows equatorial September insolation maximum, which may have caused a steeper west-east upper-ocean thermal gradient and an intensified Walker circulation in the equatorial Pacific. We propose that the warm pool thermocline warming ultimately reduced the interannual ENSO activity in the Early to Middle Holocene. Thus, a substantially increased oceanic heat content of the warm pool, acting as a negative feedback for ENSO in the past, may play its role in the ongoing global warming.

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