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

在这个奖项下，PI希望改善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洞察力。 具体而言，PI将试图重建大西洋纬向翻转环流（MOC）强度的变化，该环流通常被视为可能影响全球气候未来演变的关键因素之一。MOC速率的变化有可能导致、放大和/或传播区域甚至全球的气候变化。 PI建议调查可能发生的全新世气候变化与MOC的变化，并将这些变化与北大西洋表面水文。MOC的变化将受到限制，测量ex.231Pa/ex.230Th（Pa/Th）在高分辨率的三个高积累率的核心从北大西洋。Pa/Th是一个动力学代理提供MOC率的定量估计，但可能会被掩盖的颗粒清除的变化。为了考虑到后者，PI还将测量代表北大西洋边界清除主要区域的三个核心中的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层和深层沃茨的环流变化。这些变化将直接进行比较，以确定北大西洋表面水文和MOC之间的关系，在相同的核心的浮游有孔虫d18 O，海面温度和流冰指数的变化。的Pa/Th记录也将进行比较，底栖有孔虫d13 C和可分选的淤泥沉积物粒度，大西洋MOC的强度的两个补充措施。然后将这些剖面与现有的海洋、陆地和冰记录相关联，以评估大西洋MOC在整个全新世气候趋势以及短期变化中的重要性。例如，在一个实施例中，8.2 ka事件，小冰期，“1.5 kyr cycle”）。

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").