Investigating Climate-Related Changes in Meridional Overturning Circulation during the Holocene

根据该奖项，PIs希望改善对全新世气候变化的记录和理解，这将为未来可能的人为气候扰动提供见解。具体来说，pi将尝试重建大西洋经向翻转环流（MOC）强度的变化，MOC通常被视为可能影响未来全球气候演变的关键因素之一。MOC速率的变化有可能引起、放大和/或传播区域甚至全球的气候变化。pi建议调查与MOC变化相关的全新世气候变化的可能发生，并将这些变化与北大西洋表面水文联系起来。MOC的变化将受到ex. 231pa /ex测量的限制。北大西洋三个高积累速率岩心的高分辨率230Th （Pa/Th）。Pa/Th是一个动态代理，提供MOC速率的定量估计，但可能被颗粒清除的变化所掩盖。为了考虑到后者，pi还将测量代表北大西洋主要边界清除区域的三个岩心的Pa/Th。三个主要岩心的深度从1650米到4500米，因此有可能记录影响中深水的环流变化。这些变化将直接与同一岩心浮游有孔虫d18O、海面温度和漂冰指数的变化进行比较，以建立北大西洋表面水文与MOC的关系。Pa/Th记录还将与底栖有孔虫d13C和可分选泥沙粒度进行比较，这是大西洋MOC强度的两个互补指标。然后将这些剖面与现有的海洋、陆地和冰川记录联系起来，以评估大西洋MOC在整个全新世气候趋势以及短期变率（例如，8.2 ka事件、小冰期、“1.5 kyr周期”）中的重要性。

Under this award the PIs hope to improve documentation and understanding of climatic changes during the Holocene which would provide insight into possible future man-induced climatic perturbation. Specifically the PIs will try to reconstruct changes in the intensity of the Atlantic meridional overturning circulation (MOC), often viewed as one of the key factors that could affect the future evolution of global climate. Variations in the rate of the MOC have the potential to cause, amplify, and/or propagate climatic change regionally and even globally. The PIs are proposing to investigate the possible occurrence of Holocene climatic changes associated with changes in the MOC and to relate these changes to North Atlantic surface hydrography. Changes in MOC will be constrained by measuring ex.231Pa/ex.230Th (Pa/Th) at high resolution in three high accumulation rate cores from the North Atlantic. Pa/Th is a dynamical proxy providing quantitative estimates of the rate of MOC but which could be obscured by changes in particle scavenging. To take into account the latter, the PIs will also measure Pa/Th in three cores representing the major regions of boundary scavenging in the North Atlantic. The three primary cores span a depth from 1650m to 4500m and thus hold the potential to document changes in circulation that influence intermediate and deep waters. These changes will be compared directly to variations in planktonic foraminifera d18O, sea surface temperature, and drift ice indices in the same cores to establish the relationship between North Atlantic surface hydrography and MOC. The Pa/Th record will also be compared to benthic foraminifera d13C and sortable silt sediment grain size, two complementary measures of the intensity of Atlantic MOC. These profiles will then be related to existing marine, terrestrial and ice records to evaluate the importance of Atlantic MOC in overall Holocene climate trends as well as shorter-term variability (e. g.,8.2 ka event, Little Ice Age, "1.5 kyr cycle").