Tracking Sea-level Source Contributions: A Hemispheric Approach to High Resolution Sea-level Variation Over the Last Two Millennia

需要对前卫星时代的海平面上升进行准确估计，以便为21世纪的预估提供适当的背景，并验证地球物理和气候模式。探索海平面的地理趋势对此至关重要，因为海平面的变化不是全球均匀的，而且涉及固体地球的均衡变形以及海洋和冰盖之间的质量交换所驱动的重力和旋转变化。这项研究的目的是对南非和阿根廷大西洋沿岸过去两千年的海平面变化进行高分辨率重建。这些海岸线的相对海平面受到格陵兰岛和南极西部冰盖（GIS和WAIS）融化的影响。与海平面变化的时间和幅度有关的四个假设：(1)自公元1850年以来，阿根廷和南非的海平面上升幅度大于新英格兰，这可能表明GIS对融冰的贡献更大；(2)与小冰期（约公元1500-1850年）相关的相对海平面上升减速幅度在新英格兰大于南非或阿根廷；(3)中世纪气候异常（c. AD 1000-1500）期间，新英格兰地区相对海平面上升幅度大于南非和阿根廷；(4)公元1000年以前的相对海平面变化幅度比公元1000年至今的相对海平面变化幅度要慢。新的基于微化石的传递函数方法将用于盐沼沉积物的海平面重建，以开发高分辨率记录。这种方法与一套互补的测年方法相结合，提供了精确限制海平面细微变化的年代学（年代际到百年年际分辨率）的能力。在这个项目中，将从南非和阿根廷获得过去2000年的高分辨率相对海平面重建。并与新英格兰的现有记录进行了比较，这些记录经过了冰川均衡调整（GIA）和空间影响的校正。该项目将有助于加深对海平面变化驱动机制的理解，并可增强对21世纪海平面上升的预测，因此具有重要的社会意义。该项目将支持早期职业生涯的PI和研究生。

Accurate estimates of sea-level rise in the pre-satellite era are needed to provide appropriate context for 21st century projections and to validate geophysical and climate models. Exploring geographic trends in sea level are critical for this because sea-level changes are not globally uniform and involve isostatic deformation of the solid Earth along with gravitational and rotational changes driven by the exchange of mass between oceans and ice sheets. The aim of the study is to produce high-resolution reconstructions of sea-level change for the past two millennia along the Atlantic coasts of South Africa and Argentina. Relative sea levels along these coastlines are influenced by melting of both the Greenland and Western Antarctic Ice Sheets (GIS and WAIS). Four hypothetical hypotheses related to the timing and magnitude of sea-level changes: (1) The magnitude of sea-level rise since AD ~1850 is greater in Argentina and South Africa than New England which may indicate more ice-melt contribution from the GIS; (2) The magnitude of the deceleration in relative sea-level rise associated with the Little Ice Age (c. AD 1500-1850) is greater in New England then in South Africa or Argentina; (3) The magnitude of relative sea-level rise during the Medieval Climate Anomaly (c. AD 1000-1500) increased more in New England then in South Africa and Argentina; and (4) The magnitude of relative sea-level change prior to AD 1000 was slower than that since AD 1000 to present. New microfossil-based transfer functions approach to sea-level reconstruction in salt-marsh sediments will be used ot develop a high-resolution record. This approach combined with a suite of complementary dating methods affords the ability to precisely constrain the chronology (decadal to centennial age resolution) of subtle changes in sea level. In this project, high-resolution relative sea-level reconstructions spanning the past 2000 years will be obtained from South Africa and Argentina. And compared to existing records from New England after they have been corrected for glacial isostatic adjustment (GIA) and steric influences. This project will lead to an increased understanding of the driving mechanisms of sea-level change and could enhance predictions of 21st century sea-level rise and thus has important societal relevance. The project will support an early career PI and graduate students.