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Gong L, Holbourn A, Kuhnt W, Opdyke B, Zhang Y, Ravelo AC, Zhang P, Xu J, Matsuzaki K, Aiello I, Beil S, Andersen N. Middle Pleistocene re-organization of Australian Monsoon. Nat Commun 2023; 14:2002. [PMID: 37037802 PMCID: PMC10086051 DOI: 10.1038/s41467-023-37639-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 03/24/2023] [Indexed: 04/12/2023] Open
Abstract
The sensitivity of the Australian Monsoon to changing climate boundary conditions remains controversial due to limited understanding of forcing processes and past variability. Here, we reconstruct austral summer monsoonal discharge and wind-driven winter productivity across the Middle Pleistocene Transition (MPT) in a sediment sequence drilled off NW Australia. We show that monsoonal precipitation and runoff primarily responded to precessional insolation forcing until ~0.95 Ma, but exhibited heightened sensitivity to ice volume and pCO2 related feedbacks following intensification of glacial-interglacial cycles. Our records further suggest that summer monsoon variability at the precessional band was closely tied to the thermal evolution of the Indo-Pacific Warm Pool and strength of the Walker circulation over the past ~1.6 Myr. By contrast, productivity proxy records consistently tracked glacial-interglacial variability, reflecting changing rhythms in polar ice fluctuations and Hadley circulation strength. We conclude that the Australian Monsoon underwent a major re-organization across the MPT and that extratropical feedbacks were instrumental in driving short- and long-term variability.
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Affiliation(s)
- Li Gong
- Institute of Geosciences, Christian-Albrechts-University, D-24118, Kiel, Germany
| | - Ann Holbourn
- Institute of Geosciences, Christian-Albrechts-University, D-24118, Kiel, Germany.
| | - Wolfgang Kuhnt
- Institute of Geosciences, Christian-Albrechts-University, D-24118, Kiel, Germany
| | - Bradley Opdyke
- Research School of Earth Sciences, Australian National University, Mills Road, Acton, ACT, 2601, Australia
| | - Yan Zhang
- Ocean Sciences Department, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Ana Christina Ravelo
- Ocean Sciences Department, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Peng Zhang
- Institute of Cenozoic Geology and Environment, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, 710069, Xi'an, China
| | - Jian Xu
- Institute of Cenozoic Geology and Environment, State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, 710069, Xi'an, China
| | - Kenji Matsuzaki
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8564, Japan
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Ivano Aiello
- Department of Geological Oceanography, Moss Landing Marine Laboratories, San Jose State University, Moss Landing, CA, 95039, USA
| | - Sebastian Beil
- Institute of Geosciences, Christian-Albrechts-University, D-24118, Kiel, Germany
| | - Nils Andersen
- Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Christian-Albrechts-University Kiel, D-24118, Kiel, Germany
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Jian Z, Wang Y, Dang H, Mohtadi M, Rosenthal Y, Lea DW, Liu Z, Jin H, Ye L, Kuhnt W, Wang X. Warm pool ocean heat content regulates ocean-continent moisture transport. Nature 2022; 612:92-99. [PMID: 36261525 DOI: 10.1038/s41586-022-05302-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 08/31/2022] [Indexed: 11/09/2022]
Abstract
The Indo-Pacific Warm Pool (IPWP) exerts a dominant role in global climate by releasing huge amounts of water vapour and latent heat to the atmosphere and modulating upper ocean heat content (OHC), which has been implicated in modern climate change1. The long-term variations of IPWP OHC and their effect on monsoonal hydroclimate are, however, not fully explored. Here, by combining geochemical proxies and transient climate simulations, we show that changes of IPWP upper (0-200 m) OHC over the past 360,000 years exhibit dominant precession and weaker obliquity cycles and follow changes in meridional insolation gradients, and that only 30%-40% of the deglacial increases are related to changes in ice volume. On the precessional band, higher upper OHC correlates with oxygen isotope enrichments in IPWP surface water and concomitant depletion in East Asian precipitation as recorded in Chinese speleothems. Using an isotope-enabled air-sea coupled model, we suggest that on precessional timescales, variations in IPWP upper OHC, more than surface temperature, act to amplify the ocean-continent hydrological cycle via the convergence of moisture and latent heat. From an energetic viewpoint, the coupling of upper OHC and monsoon variations, both coordinated by insolation changes on orbital timescales, is critical for regulating the global hydroclimate.
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Affiliation(s)
- Zhimin Jian
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China.
| | - Yue Wang
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China.
| | - Haowen Dang
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China.
| | - Mahyar Mohtadi
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Yair Rosenthal
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, USA.,Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, USA
| | - David W Lea
- Department of Earth Science, University of California, Santa Barbara, CA, USA
| | - Zhongfang Liu
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
| | - Haiyan Jin
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
| | - Liming Ye
- Second Institute of Oceanography, Ministry of Natural Resource, Hangzhou, China
| | - Wolfgang Kuhnt
- Institute of Geosciences, Christian-Albrechts-Universität, Kiel, Germany
| | - Xingxing Wang
- State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
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Thermal coupling of the Indo-Pacific warm pool and Southern Ocean over the past 30,000 years. Nat Commun 2022; 13:5457. [PMID: 36115856 PMCID: PMC9482618 DOI: 10.1038/s41467-022-33206-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 09/06/2022] [Indexed: 11/08/2022] Open
Abstract
The role of the tropical Pacific Ocean and its linkages to the southern hemisphere during the last deglacial warming remain highly controversial. Here we explore the evolution of Pacific horizontal and vertical thermal gradients over the past 30 kyr by compiling 340 sea surface and 7 subsurface temperature records, as well as one new ocean heat content record. Our records reveal that La Niña-like conditions dominated during the deglaciation as a result of the more intense warming in the western Pacific warm pool. Both the subsurface temperature and ocean heat content in the warm pool rose earlier than the sea surface temperature, and in phase with South Pacific subsurface temperature and orbital precession, implying that heat exchange between the tropical upper water column and the extratropical Southern Ocean facilitated faster warming in the western Pacific. Our study underscores the key role of the thermal coupling between the warm pool and the Southern Ocean and its relevance for future global warming. The mechanism of the last deglacial global warming is key for future climate. Here, the authors shed light on the pivotal role of the thermal coupling between the western Pacific warm pool and the Southern Ocean.
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Holocene melting of the West Antarctic Ice Sheet driven by tropical Pacific warming. Nat Commun 2022; 13:2434. [PMID: 35595753 PMCID: PMC9123186 DOI: 10.1038/s41467-022-30076-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 04/15/2022] [Indexed: 12/05/2022] Open
Abstract
The primary Antarctic contribution to modern sea-level rise is glacial discharge from the Amundsen Sea sector of the West Antarctic Ice Sheet. The main processes responsible for ice mass loss include: (1) ocean-driven melting of ice shelves by upwelling of warm water onto the continental shelf; and (2) atmospheric-driven surface melting of glaciers along the Antarctic coast. Understanding the relative influence of these processes on glacial stability is imperative to predicting sea-level rise. Employing a beryllium isotope-based reconstruction of ice-shelf history, we demonstrate that glaciers flowing into the Amundsen Sea Embayment underwent melting and retreat between 9 and 6 thousand years ago. Despite warm ocean water influence, this melting event was mainly forced by atmospheric circulation changes over continental West Antarctica, linked via a Rossby wave train to tropical Pacific Ocean warming. This millennial-scale glacial history may be used to validate contemporary ice-sheet models and improve sea-level projections. Ice loss from the Amundsen Sea sector of West Antarctica is rapidly accelerating. Here, the authors reveal that this region also underwent thinning and retreat from 9 to 6 thousand years ago, due to atmospheric connections with a warming tropical Pacific.
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Enhanced North Pacific subtropical gyre circulation during the late Holocene. Nat Commun 2021; 12:5957. [PMID: 34642314 PMCID: PMC8511172 DOI: 10.1038/s41467-021-26218-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/14/2021] [Indexed: 11/08/2022] Open
Abstract
The North Pacific Subtropical Gyre circulation redistributes heat from the Western Pacific Warm Pool towards the mid- to high-latitude North Pacific. However, the driving mechanisms of this circulation and how it changed over the Holocene remain poorly understood. Here, we present alkenone-based sea surface temperature reconstructions along the Kuroshio, California and Alaska currents that cover the past ~7,000 years. These and other paleorecords collectively demonstrate a coherent intensification of the boundary currents, and thereby the basin-scale subtropical gyre circulation, since ~3,000-4,000 years ago. Such enhanced circulation during the late Holocene appears to have resulted from a long-term southward migration of the Intertropical Convergence Zone, associated with Holocene ocean cooling. Our results imply that the North Pacific Subtropical Gyre circulation could be weakened under future global warming.
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