COLLABORATIVE RESEARCH: SEA-LEVEL RISE AND SALT-MARSH RESPONSE: A PALEO PERSPECTIVE

对未来相对海平面(RSL)上升的准确预测对于有效管理沿海人口、基础设施和包括盐沼在内的生态系统至关重要。过去4000年的海平面重建为理解现代和预测的海平面上升速度提供了一个背景，因为地球的气候系统相对没有变化。我们将开发两个新的北卡罗来纳州RSL代理重建，以识别与过去4000年来感知的海平面稳定性的正负偏离，并支持开发新的预测模型，在该模型中，海平面-气候关系可以随时间变化。这些重建将检验一个普遍存在的假设，即在过去2000年里，大冰盖融化导致的海平面上升可以忽略不计，并将有助于限制陆地平面垂直运动的速度。重建所产生的数据将用于进一步发展盐沼对海平面上升的反应模式，这将为沿海管理界提供宝贵的服务和工具，为决策提供信息。虽然有关于晚全新世全球和区域替代温度数据的汇编，但对这一时期的海平面变化知之甚少，海平面对已知气候偏差的反应也是未知的，如中世纪气候异常、小冰期和20世纪变暖。利用保存在北卡罗来纳州盐沼沉积物中的有孔虫，我们将产生跨越过去4000年的第一个连续的、高分辨率(十进制和分米)的RSL重建。海平面重建将校准新的海平面上升预测模型，以提高预测的准确性和区域有效性。新的记录将扩展现有的重建，以检验以下假设，这些假设对于理解气候-海平面关系至关重要：(1)区域RSL在公元1000年之前是稳定的；(2)2000年前结束的大冰盖融化对海平面上升的贡献。来自盐沼沉积物的重建也为预测未来海平面上升的生态影响提供了一个古老的视角。代理海平面记录将首次验证沼泽平衡模型(MEM)。MEM描述了海平面变化对盐沼植被的调节。如果海平面上升的速度快于盐沼沉积物的沉积速度，盐沼植被的生产力就会下降，导致这些重要的沿海生态系统退化或丧失。替代海平面记录将检验MEM的一个中心前提，即(3)稳定的沉积物有机质(SOM)浓度与重建的RSL上升速率成反比。

Accurate projections of future relative sea-level (RSL) rise are crucial for effective management of coastal populations, infrastructure, and ecosystems including salt marshes. Sea-level reconstructions from the last 4000 years provide a context for understanding modern and projected rates of sea-level rise because Earth's climate system is relatively unchanged. We will develop two new proxy RSL reconstructions from North Carolina to identify positive and negative departures from the perceived stability of sea level during the last 4000 years and support development of new predictive models in which the sea level-climate relationship can vary through time. The reconstructions will test the widely held assumption that sea-level rise from melting of large ice sheets was negligible during the last 2000 years and will help constrain rates of vertical land level movement. Data generated for the reconstructions will be used to further develop a model of salt-marsh response to sea-level rise that will provide a valuable service and tool to the coastal management community for informing policy decisions. While there are compilations of global and regional proxy temperature data for the late Holocene, little is known about sea-level variability during this period and the response of sea level to known climate deviations such as the Medieval Climate Anomaly, Little Ice Age, and 20th century warming is unknown. Using foraminifera preserved in North Carolina salt-marsh sediments, we will produce the first continuous, high resolution (decadal and decimeter) RSL reconstruction spanning the last ~4000 years. The sea-level reconstructions will calibrate new predictive models of sea-level rise to improve the accuracy and regional validity of projections. The new record will extend existing reconstructions to test the following hypotheses that are vital for understanding the climate sea-level relationship: (1) regional RSL was stable before AD 1000; and (2) the contribution from melting of large ice sheets sea-level rise ended 2000 years ago. Reconstructions derived from salt marsh sediment also provide a paleo perspective for predicting the ecological effects of future sea-level rise. The proxy sea-level record will validate, for the first time, the Marsh Equilibrium Model (MEM). The MEM describes the regulation of salt-marsh vegetation by changes in sea level. If sea-level rise is faster than the rate of salt-marsh sediment accretion, the productivity of salt-marsh vegetation will decline, resulting in the degradation or loss of these important coastal ecosystems. The proxy sea level record will test a central premise of the MEM that (3) Stable sediment organic matter (SOM) concentration varies inversely with the reconstructed rate of RSL-rise.