High-Resolution Records of Late Holocene Sea level from Southern New England

新英格兰南部全新世晚期海平面的高分辨率记录

• 批准号: 0309129
• 负责人: Jeffrey Donnelly
• 金额: $ 17.8万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2006-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0309129&HistoricalAwards=false
• 关键词: Resolution; Records; Late; Holocene; Sea

EAR-0309129ABSTRACTFaced with expectations of accelerated sea-level rise due to anthropogenic warming of the global climate system, decision makers, scientists and the general public have become increasingly concerned about potential risks to coastal communities and ecosystems. Gaining understanding of how changes in sea level may be linked to changes in climate is important in order to project future changes and possibly mitigate socio-economic impacts. In the northeastern United States geological records generally suggest sea-level rise of about 1 mm/year or less for the last few thousand years while instrumental records indicate rates of 2-3 mm/year over the past 150 years. The apparent discord between long-term and short-term records is often interpreted to indicate an increase in the rate of sea-level rise in the last few hundred years that may be the result of the warming global climate. Determining the timing of this apparent acceleration is crucial if we are to understand the relationship between sea-level changes and fluctuations in climate.Intellectual MeritMany previous studies have exploited the narrow vertical habitat range of coastal wetland species to reconstruct past sea levels, but most lack the dating resolution to resolve historic sea-level changes. Well-constrained, high-resolution records of sea-level change are necessary if we are to be able to link the geologic record with the historic instrumental records. Reliable age estimates of sea-level indicators are necessary in order to establish a history of sea-level change for the historic period (last 400 years).Radiocarbon methods are useful in this interval, but large uncertainties associated with calibration for secular changes in atmospheric C-14 concentrations require that other dating methods also be employed to help reduce these uncertainties. Dated stratigraphic markers such as those attributable to anthropogenic landscape changes and pollution can provide important constraints on the age of sea-level indicators and can substantially reduce uncertainties associated with radiocarbon dating methods. Some recent attempts to reconstruct high-resolution records of sea-level changes in New England from coastal wetland sediments may suggest that the recent apparent increase in the rate of sea-level rise may have begun in the 17th or 18th century A.D., predating the climate warming of the last 150 years by several centuries. However, these studies have relied on non-basal samples that may have been displaced vertically by autocompaction of the peat column. Using an approach that recovers contiguous sections of basal marsh sediments deposited over a glacial erratic and a combination of radioisotopic and stratigraphic dating techniques, I have constructed a 1300-year sea-level chronology from Barn Island, Connecticut that indicates the recent acceleration in the rate of sea-level rise may have initiated in the late 19th century. Reproducing the results from Barn Island and other locations is critically important because changes in geomorphology that alter the tidal range at a site can introduce local changes of sea level. Here, I propose to use the approach described above to extend the instrumental record of sea-level change by attempting to replicate the results of this initial study at another site at Barn Island and two sites at Plum Island Marsh in northern Massachusetts. The results will provide critical insight into how sea level has changed over the last 1500 years and expand our understanding of the links between climate and sea-level change.Broader ImpactsCoastal resource managers and policy makers will be able to use the results of this study to make informed decisions regarding appropriate management practices and regulatory strategies. The results of this study would be extremely useful to stakeholders: coastal zone managers; habitat restoration groups; land managers; business interests concerned with managing risk; coastal property owners and coastal scientists. With billions of dollars and human lives at risk, I see this research as providing vital information for society. In addition, I am committed to helping train the next generation of geoscientists by providing them with practical, "hands on," interdisciplinary research experience and I plan to include a graduate student and at least one undergraduate in this project. I endeavor to recruit students from groups underrepresented in the geological sciences whenever possible. In addition, the geological and ecological lessons learned from this study, as well as the potential societal implications, will be integrated into undergraduate and graduate coursework including seminars and field trips. The results will be presented at a professional meeting and we will publish our findings in one or more peer-reviewed journals.

面对全球气候系统人为变暖导致海平面加速上升的预期，决策者、科学家和公众越来越担心沿海社区和生态系统面临的潜在风险。了解海平面变化如何与气候变化相联系，对于预测未来的变化并可能减轻社会经济影响十分重要。在美国东北部，地质记录一般表明海平面在过去几千年中每年上升约1毫米或更少，而仪器记录表明在过去150年中海平面每年上升2-3毫米。长期和短期记录之间的明显不一致通常被解释为表明海平面在过去几百年中上升的速度加快，这可能是全球气候变暖的结果。如果我们要了解海平面变化和气候波动之间的关系，确定这种明显加速的时间是至关重要的。智力价值许多以前的研究利用沿海湿地物种狭窄的垂直栖息地范围来重建过去的海平面，但大多数缺乏解决历史海平面变化的年代分辨率。如果我们要将地质记录与历史仪器记录联系起来，就必须有严格约束的、高分辨率的海平面变化记录。为了建立历史时期(过去400年)海平面变化的历史，必须对海平面指标进行可靠的年龄估计。放射性碳法在这段时间内是有用的，但与大气C-14浓度长期变化的校准相关的巨大不确定性要求也采用其他测年方法来帮助减少这些不确定性。可归因于人为地貌变化和污染的过时地层标志可对海平面指标的年龄提供重要限制，并可大大减少与放射性碳测年方法有关的不确定性。最近一些从沿海湿地沉积物重建新英格兰海平面变化高分辨率记录的尝试可能表明，最近海平面上升速度的明显增加可能始于公元17世纪或18世纪，比过去150年的气候变暖早了几个世纪。然而，这些研究依赖于非基础样品，这些样品可能因泥炭柱的自动压实而垂直移位。我使用了一种恢复冰川上沉积的连续部分底部沼泽沉积物的方法，并结合放射性同位素和地层学测年技术，建立了康涅狄格州巴恩岛1300年的海平面年代学，表明海平面最近的加速上升速度可能始于19世纪末。复制来自谷仓岛和其他地点的结果是至关重要的，因为改变地点潮汐范围的地貌变化可能会引起当地海平面的变化。在这里，我建议使用上述方法来扩展海平面变化的仪器记录，尝试在巴恩岛的另一个地点和马萨诸塞州北部的普勒姆岛沼泽的两个地点复制这项初步研究的结果。研究结果将提供对过去1500年海平面变化的重要洞察，并扩大我们对气候和海平面变化之间联系的理解。广泛影响沿海资源管理者和政策制定者将能够利用这项研究的结果，就适当的管理做法和监管战略做出明智的决定。这项研究的结果将对利益攸关方极为有用：沿海地区管理者、生境恢复团体、土地管理者、关心管理风险的企业利益集团、沿海财产所有者和沿海科学家。在数十亿美元和生命危险的情况下，我认为这项研究为社会提供了重要信息。此外，我致力于帮助培训下一代地球科学家，为他们提供实践的、跨学科的研究经验，我计划在这个项目中包括一名研究生和至少一名本科生。只要有可能，我就努力从地质科学中代表性不足的群体中招收学生。此外，从这项研究中学到的地质学和生态学经验，以及潜在的社会影响，将被纳入本科生和研究生课程，包括研讨会和实地考察。结果将在专业会议上公布，我们将在一本或多本同行评议的期刊上发表我们的研究结果。