The response of the Subarctic North Pacific to abrupt climate change: Reconstructing dust flux and biological productivity during the last deglaciation

哥伦比亚大学拉蒙特-多尔蒂地球天文台的研究人员这项研究的重点是测试北太平洋次北冰洋对气候变化的反应，并有可能减缓气候变化。亚北极太平洋构成了高营养低叶绿素区域之一，在那里，生物泵将碳从大气转移到深海的效率相对较低。中国沙漠矿物粉尘中含有的铁被认为可以刺激该地区的生物生产。然而，我们对尘埃、生物生产和气候之间的联系的理解受到阻碍，原因是北太平洋次北冰洋缺乏可靠的尘埃通量记录，以及以往研究中用于重建生物生产力的具体技术之间长期存在的差异。在最近一次由德国领导的考察队(INOPEX)中收集的岩心提供了对这一以前基本上采样不足的偏远地区的广泛覆盖，并提供了一个独特的研究机会。研究人员将使用一套地球化学指标(钍和铀同位素、氦同位素和微量元素)，绘制粉尘供应和生物生产力的空间模式图，并通过与卫星和其他观测的现有信息进行比较来进行校准。然后，研究人员将把他们的校准应用于岩心下方的记录，重点放在最后一次冰川消融的突然气候变化上。从寒冷和尘土飞扬的海因里希阶梯1开始，经过尘土飞扬的博林-阿勒德暖期，再回到年轻的仙女座接近冰川的条件，这一序列提供了一个出色的自然实验，以测试亚北区北太平洋？S生态系统如何响应和调节气候变化。广泛的影响包括本科生和高中生参与研究，培训当地高中教师，以及加强国际合作。此外，这一国际合作的结果将为决策者提供信息，帮助他们探索在海洋中进行大规模人工铁施肥，作为减缓全球变暖的一种地球工程选择。对长期碳封存能力和对生态系统的影响的可靠估计仍然存在争议。这项工作将评估过去对全球海洋关键区域之一的铁输入的自然变化的反应，并反过来将为制定关于人工铁施肥可能的效果和后果的定量预测奠定基础。

The focus of this study by researchers at the Lamont-Doherty Earth Observatory of Columbia University is to test how the Subarctic North Pacific responds to and potentially mitigates climate change. The Subarctic Pacific constitutes one of the high-nutrient-low chlorophyll regions where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. Iron, contained in mineral dust from Chinese deserts, is thought to stimulate biological production in this region. However, our understanding of the links between dust, biological production and climate is hampered by the lack of reliable dust flux records in the Subarctic North Pacific as well as longstanding discrepancies among specific techniques that have been used in previous research to reconstruct biological productivity. Cores collected during a recent German-led expedition (INOPEX) provide extensive coverage of this previously largely undersampled remote region and offer a unique opportunity for study. Using a suite of geochemical proxies (thorium and uranium isotopes, helium isotopes, and trace elements), the researchers will produce a map of the spatial pattern of dust supply and biological productivity and calibrate it by comparing to present day information from satellites and other observations. The researchers will then apply their calibration to down-core records, focusing on the abrupt climate changes of the last deglaciation. The sequence from the cold and dusty Heinrich Stadial 1, through the dust-poor Bølling-Allerød warm period and a return to the near-glacial conditions of the Younger Dryas stadial provides for an outstanding natural experiment to test how the Subarctic North Pacific?s ecosystem responds to and mediates climate change.Broader impacts include involvement of undergraduates and high school students in the research, training of local high school teachers, and enhancing international collaborations. In addition, the results of this international collaboration will inform decision makers in exploring large-scale artificial iron fertilization of the ocean as a geo-engineering option to mitigate global warming. Reliable estimates of the long-term carbon sequestration capacity and impact on the ecosystem remain controversial. This work will assess the past response to natural variability of iron input in one of the key regions of the global ocean and will, in turn, lay the foundation to develop quantitative predictions about the possible efficacy and consequences of artificial iron fertilization.