Collaborative Research: Sub-Millennial Hydroclimatic Variability in the Northeastern United States during the Holocene

水文变异性对社会构成重大挑战。然而，人们对水文变化的潜力仍然知之甚少。小湖盆内的沉积模式记录了过去水位的变化，可以用来追踪水分随时间的变化。这项研究评估了马萨诸塞州过去11000年里几千年和几个世纪尺度上的水文变化，那里现有的湖泊沉积数据似乎表明过去干旱频率的显著变化。创建、分析和综合新的、分辨率高的沉积数据，结合详细的化石花粉数据，用于评估次千年水文变异性、其控制因素及其影响。人们对过去的水文气候变化了解甚少，特别是在湿润的温带地区。人们对这种变化的频率、幅度和原因知之甚少。美国东北部湖泊水位变化的地层记录可以为重要的区域到全球气候过程提供新的见解。美国东北部湖泊的高分辨率地球物理调查和沉积物岩心记录了沉积记录中具有气候意义的模式，并指出了高频水文变异的可能变化。现有资料似乎表明，在6000年至2000年之间，存在一系列千年和次千年持续时间的低湖林，而在全新世早期和晚期，这些时间尺度上的变化不大。这项拨款研究了四个湖泊，以产生详细的湖平面历史。利用这些历史的异同来评价过去的水文气候变化，并更好地了解明显高频变化的原因。温度重建也表明，全新世中期美国东北部的冬季比现代冬季更温暖。鉴于有可能通过类比了解未来气候变暖的影响，该项目评估了过去的温暖和水文气候变化之间可能的联系。通过比较沉积物和花粉数据，该小组还研究了生物对过去气候变化的反应。更广泛的影响水是一种重要的资源，干旱的风险是一个主要的社会问题。在像美国东部这样潮湿、人口稠密的地区，存在着潜在的巨大水文变化的问题。对未来气候变暖的预期增加了了解驱动水资源变化机制的需求。该研究为区域水文变异性的范围及其生态影响提供了重要的基线数据。这些数据有助于深入了解水资源对未来气候条件的反应。这项研究的结果对从农业企业到栖息地保护组织和关心供水管理和减轻干旱风险的市政当局的各种利益相关者都很有用。资源管理者和政策制定者可以访问结果以做出明智的决策。该项目在促进创新科学的同时，也促进了青年科研人员的发展。

Hydrologic variability poses significant challenges to society. However, the potential for hydrologic change remains poorly understood. Sedimentary patterns within small lake basins record past changes in water levels and can be used to track shifts in moisture availability over time. This study assesses hydrologic variability at the scale of millennia and centuries over the past 11,000 years in Massachusetts, where existing lake sedimentary data appear to indicate significant changes in the frequency of past droughts. The creation, analysis, and synthesis of new, well-resolved sedimentary data, in combination with detailed fossil pollen data, is used to evaluate sub-millennial hydrologic variability, its controls, and its effects.Intellectual MeritPast hydroclimatic variation is poorly understood, especially in humid temperate regions. Little is known about the frequency, magnitude, and cause of variations. Stratigraphic records of lakelevel change in the northeastern U.S. can provide new insight into important regional to global climatic processes. High-resolution geophysical surveys and sediment cores of lakes in the northeastern U.S. have documented climatically meaningful patterns in the sedimentary record - and indicate possible changes in high-frequency hydrologic variability. Existing data appear to indicate a series of low lake stands of millennial and sub-millennial duration between 6000 and 2000 years ago in contrast to little variability on these time scales during earlier and later portions of the Holocene. This grant studies four lakes to produce detailed lake-level histories. Similarities and differences among the histories are used to evaluate past hydroclimatic changes and to better understand the causes of the apparent high frequency variation. Temperature reconstructions also indicate warmer than modern winters in the northeastern U. S. in the mid-Holocene. Given the potential to understand the effects of future climate warming through analogy, this project evaluates possible linkages between past warmth and hydroclimatic variation. By comparing sediment and pollen data, the group also investigates biotic responses to past climatic changes.Broader ImpactsWater is a vital resource and risk of drought is a major societal concern. Questions exist about the potential for dramatic hydrologic change in humid, heavily populated regions like the eastern U.S. Expectations of future climate warming increase the need to understand the mechanisms that drive changes in water resources. This study offers important baseline data regarding the range of regional hydrologic variability and its ecological impacts. This data provides insight into water resource responses to climatic conditions like those predicted for the future. The results of this study are useful to a wide variety of stakeholders from agricultural businesses to habitat conservation groups and municipalities concerned with managing water supplies and mitigating drought risk. Resource managers and policy makers have access to the results to make informed decisions. This project also advances the development of young researchers while promoting innovative science.