Collaborative Research: Exploring Late Holocene Sedimentary Archives of Extreme Storms in the Northeastern United States

全球气候系统可能发生的快速变化引发了人们对热带气旋对沿海社区和生态系统的潜在风险的担忧。了解过去热带气旋活动的变化如何与气候变化联系起来，将有助于预测未来的变化，并可能减轻社会经济影响。通过记录过去2000年强烈飓风活动的变化，该项目将从新泽西州到马萨诸塞州沿海的沉积物记录中重建强烈飓风的登陆，并将扩展北大西洋西部暂时有限的仪器记录。强烈飓风对人口稠密地区的生命和资源构成重大威胁，并能广泛改变沿海地貌。鉴于强烈飓风登陆的相对罕见（例如，新英格兰每100年1次）和仪器记录的短暂性，人们对过去强烈飓风活动的模式知之甚少。飓风活动的长期记录（1000年或更长时间）的发展将使研究过去气候变化如何影响飓风发生的频率、强度和区域成为可能。风暴潮和海浪产生的冲积物保存在沿海沉积环境中，可以提供严重风暴的记录。先前的研究表明，强烈的飓风袭击会产生一种独特的沉积特征，可以用来重建这些事件的长期记录。在强烈的飓风登陆期间，美国东北部广阔的后屏障盐沼和沿海淡水池塘很好地容纳了沉积物。这些通常低能量的环境主要是细粒的高有机沉积物，除了极端风暴期间海滩和近岸环境中偶尔沉积的粗粒矿物沉积物。从每个地点的一系列岩心中获得的沉积物可用于绘制风暴诱发沉积物的地图和日期。该项目将在三个研究区域内开发过去2000年强烈飓风的沉积记录：1)纽约/新泽西湾，2)东部CT/西部RI，以及3)马萨诸塞州Buzzards湾。通过各种同位素和地层学方法，将对风暴诱发的沉积物进行识别、测绘和定年。在每个研究区域内具有不同洪水阈值的多个站点将允许估计单个史前风暴潮事件的海拔和分布，并确定哪些风暴诱发的沉积物可能是由强烈飓风袭击造成的。根据由此产生的强烈飓风活动记录，该小组将探索这些事件的频率与已知的气候振荡（如小冰期和中世纪温暖期）以及气候变化指数（如ENSO和北大西洋涛动）之间的联系。更广泛的影响本研究的结果将对沿海资源管理者、减灾管理者和政策制定者特别有用，并将使这些群体能够就适当的管理实践和监管策略做出明智的决策。其他利益相关者（海岸带管理者、栖息地恢复团体、土地管理者、与风险管理有关的商业利益集团、沿海财产所有者和沿海科学家）将从这个项目的成果中受益。这项研究应该有助于制定计划，减少人类生命和宝贵的沿海资源的损失。

The potential for rapid changes in the global climate system raises concerns about potential risks to coastal communities and ecosystems from tropical cyclones. Understanding how past changes in tropical cyclone activity may be linked to changes in climate will aid the projection of future changes and possibly mitigate socio-economic impacts. By recording how past changes in intense hurricane activity has varied during the past 2000 years, this project will reconstruct landfalls from intense hurricanes from sediment records along the coast from New Jersey to Massachusetts and will extend the temporally limited instrumental record in the western North Atlantic Ocean.Intellectual MeritIntense hurricanes pose a significant threat to lives and resources in heavily populated regions and can extensively modify coastal landforms. Given the relative rarity of intense hurricanes making landfall (e.g. 1 per 100 yr in New England) and the shortness of the instrumental record, little is known about past patterns of intense hurricane activity. The development of long-term records (1000 years or longer) of hurricane activity would make it possible to examine how past climate change may have influenced the frequency, intensity, and region of occurrence of hurricanes. Storm surge and waves create overwash deposits that are preserved within coastal sedimentary environments and that can provide a record of severe storms. Previous work has shown that intense hurricane strikes produce a distinctive sedimentary signature that can be used to reconstruct long-term records of these events. Extensive backbarrier salt marshes and coastal freshwater ponds in the northeastern United States are well situated to receive sediments during intense hurricane landfalls. These normally low-energy environments are dominated by fine-grained highly organic sediments, with the exception of episodic deposition of coarser-grained mineral sediments from the beach and near-shore environment during extreme storms. Sediment obtained from a series of cores from each site can be used to map and date storm-induced deposits. This project will develop sedimentary records of intense hurricanes for the last 2000 years within three study areas: 1) New York/New Jersey Bight, 2) eastern CT/western RI, and 3) Buzzards Bay, MA. Storm-induced deposits will be identified, mapped and dated with a variety of isotopic and stratigraphic methods. Multiple sites with different flooding thresholds within each study area will allow estimation of the elevation and distribution of individual prehistoric storm surge events and to determine which storm-induced deposits likely resulted from intense hurricane strikes. With the resulting records of intense hurricane activity, the group will explore links between the frequency of these events and known climate oscillations such as the Little Ice Age and Medieval Warm Period as well as indices of climate variability such as ENSO and the North Atlantic Oscillation.Broader ImpactsThe results of this study will be particularly useful to coastal resource managers, disaster mitigation managers, and policy makers and will enable these groups to make informed decisions regarding appropriate management practices and regulatory strategies. Other stakeholders (coastal zone managers; habitat restoration groups; land managers; business interests concerned with managing risk; coastal property owners and coastal scientists) will benefit from the results of this project. The research should help planning to reduce the loss of human lives and valuable coastal resources.