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

水文变化对社会构成重大挑战。然而，水文变化的可能性仍然知之甚少。小型湖盆内的沉积模式记录了过去水位的变化，并可用于跟踪水分可获得性随时间的变化。这项研究评估了马萨诸塞州过去11,000年来千年和数百年的水文变异性，那里现有的湖泊沉积数据似乎表明，过去干旱的频率发生了重大变化。新的、分辨率良好的沉积数据的创建、分析和综合，结合详细的化石花粉数据，被用来评估亚千年的水文变异性、其控制和影响。人们对过去的水文气候变化知之甚少，特别是在潮湿的温带地区。人们对这种变化的频率、大小和原因知之甚少。美国东北部湖泊水位变化的地层学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具有气候意义的模式-并表明高频水文变异性可能发生变化。现有数据似乎表明，在6000至2000年前，出现了一系列持续时间为千年和亚千年的低湖水位，而在全新世早期和晚些时候，这些时间尺度上的变化很小。这笔赠款研究了四个湖泊，以制作详细的湖泊水平历史。历史上的相似性和差异性被用来评估过去的水文气候变化，并更好地理解明显高频变化的原因。温度重建也表明，在全新世中期，美国东北部的冬天比现代要暖和。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气候变暖与水文气候变化之间可能存在的联系。通过比较沉积物和花粉的数据，该小组还调查了生物对过去气候变化的反应。在像美国东部这样的潮湿、人口稠密的地区，存在着可能发生戏剧性水文变化的问题。对未来气候变暖的预期增加了理解推动水资源变化的机制的必要性。这项研究提供了关于区域水文变化范围及其生态影响的重要基线数据。这些数据为水资源对气候条件的反应提供了洞察，就像对未来预测的那样。这项研究的结果对从农业企业到栖息地保护团体和涉及管理供水和减轻干旱风险的市政当局的各种利益攸关方都很有用。资源经理和政策制定者可以访问结果，以做出明智的决策。该项目还促进了青年研究人员的发展，同时促进了创新科学。

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.