Institute of Geosciences, Christian-Albrechts-University, D-24118, Kiel, Germany.
Research School of Earth Sciences, Australian National University, Mills Road, Acton, ACT, 2601, Australia.
Nat Commun. 2023 Apr 10;14(1):2002. doi: 10.1038/s41467-023-37639-x.
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 pCO 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.
由于对强迫过程和过去变异性的理解有限，澳大利亚季风对气候变化边界条件的敏感性仍然存在争议。在这里，我们在澳大利亚西北部的一个沉积物序列中重建了中更新世过渡期（MPT）的澳大利亚夏季季风排放和风生冬季生产力。我们表明，季风降水和径流量主要响应岁差进动强迫，直到约 0.95Ma，但在冰期-间冰期旋回加剧后，对冰量和 pCO 相关反馈的敏感性增强。我们的记录进一步表明，过去 160 万年以来，季风在岁差波段的变化与印度-太平洋暖池的热演化和沃克环流的强度密切相关。相比之下，生产力代理记录始终跟踪冰期-间冰期的变化，反映了极地冰波动和哈德利环流强度变化的节奏。我们的结论是，澳大利亚季风在 MPT 期间经历了重大的重新组织，而中纬度的反馈在驱动短期和长期变异性方面发挥了重要作用。
