Northern and southern hemispheric influences—particularly changes in Southern Hemisphere westerly winds (SSW) and Southern Ocean ventilation—triggered the stepwise atmospheric CO2 increase that accompanied the last deglaciation. One approach for gaining potential insights into past changes in SWW/CO2 upwelling is to reconstruct the positions of the northern oceanic fronts associated with the Antarctic Circumpolar Current. Using two deep-sea cores located ~600 km apart off the southern coast of Australia, we detail oceanic changes from ~23 to 6 ka using foraminifer faunal and biomarker alkenone records. Our results indicate a tight coupling between hydrographic and related frontal displacements offshore South Australia (and by analogy, possibly the entire Southern Ocean) and Northern Hemisphere (NH) climate that may help confirm previous hypotheses that the westerlies play a critical role in modulating CO2 uptake and release from the Southern Ocean on millennial and potentially even centennial timescales. The intensity and extent of the northward displacements of the Subtropical Front following well-known NH cold events seem to decrease with progressing NH ice sheet deglaciation and parallel a weakening NH temperature response and amplitude of Intertropical Convergence Zone shifts. In addition, an exceptional poleward shift of Southern Hemisphere fronts occurs during the NH Heinrich Stadial 1. This event was likely facilitated by the NH ice maximum and acted as a coup-de-grâce for glacial ocean stratification and its high CO2 capacitance. Thus, through its influence on the global atmosphere and on ocean mixing, “excessive” NH glaciation could have triggered its own demise by facilitating the destratification of the glacial ocean CO2 state.

中文翻译：

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澳大利亚南部在最后一次冰消期间的水文变化和可能的半球间联系

北半球和南半球的影响——特别是南半球西风 (SSW) 和南大洋通风的变化——触发了逐步的大气 CO2伴随最后一次冰消期的增加。一种获得对过去 SWW/CO 变化的潜在洞察力的方法2上升流是重建与南极绕极流相关的北洋锋的位置。使用位于澳大利亚南部海岸约 600 公里处的两个深海岩心，我们使用有孔虫动物群和生物标志物烯酮记录详细说明了从约 23 到 6 ka 的海洋变化。我们的研究结果表明，南澳大利亚近海（以及类似地，可能是整个南大洋）和北半球（NH）气候之间的水文和相关锋面位移之间存在紧密耦合，这可能有助于证实之前的假设，即西风带在调节二氧化碳中起关键作用2在千年甚至可能是百年时间尺度上从南大洋吸收和释放。随着北半球冰盖消融的进行，副热带锋向北位移的强度和范围似乎随着北半球冰盖消融的进行而减小，并且与北半球温度响应的减弱和热带辐合带位移的幅度平行。此外，在 NH Heinrich Stadial 1 期间，南半球锋面发生了异常的极移。这一事件可能是由 NH 冰最大值促进的，并作为冰川海洋分层及其高 CO 的致命一击2电容。因此，通过其对全球大气和海洋混合的影响，“过度”的 NH 冰川作用可能会通过促进冰川海洋 CO 的去分层而引发其自身的消亡2状态。