Synchronized records of Holocene Circum-Baltic environmental change

环波罗的海生态系统对自然气候强迫和人类影响都高度敏感。波罗的海本身的沉积物以及周围的陆地环境档案都很好地记录了它自最后一次消冰期以来的演变。现有的研究表明，在年际到千年的时间尺度上，由内部和外部强迫机制的复杂相互作用引发的环境变异性具有很强的空间梯度。尽管现有的古环境信息丰富多样，但对全新世海陆耦合波罗的海生态系统发展的全面认识仍然有限。主要原因是不同类型环境档案中强迫机制的时空变化范围和代理响应的时间、强度和阈值不同。BaltRap网络旨在整合来自南部波罗的海地区的海洋，年度层压（varved）湖泊沉积物和树木年轮记录，以全面了解档案特定的代理响应，以短期和长期气候变化和振荡，以及区分自然变率与日益增加的人类影响，达到尽可能高的“季节性”分辨率。然而，由于BaltRap侧重于波罗的海南部地区，因此要全面了解环波罗的海生态系统的响应，需要将该方法向北扩展，该方法基于斯堪的纳维亚半岛的湖泊沉积物和树木年轮记录。这是至关重要的，因为波罗的海北部地区的气候和人类发展与南部地区有很大的不同。此外，对代理响应的领先和滞后的多档案调查需要对所考虑的档案进行气候无关的同步，从而最大限度地减少个人时间上的不确定性。在本提案中，我们的目标是利用Kälksjön湖及其集水区（瑞典中部）的湖泊沉积物和树木年轮记录，建立新的季节性解决的全新世气候和人类活动代用记录，以区分斯堪的纳维亚对环波罗的海生态系统的独特影响，并将BaltRap方法向北扩展。我们应用新颖的10Be同步工具将斯堪的纳维亚湖Kälksjön记录精确同步到现有的波罗的海南部海洋和湖泊沉积物档案中。研究的最终目标是首次基于同步多档案代理记录对波罗的海地区全新世的环境梯度进行调查。这项工作将提高我们对新的跨波罗的海南北样带对气候和人类强迫的时空生态系统响应的理解，并为更全面地了解环波罗的海环境动态迈出了一步，有助于更好地预测21世纪的未来变化。

The Circum-Baltic ecosystem is highly sensitive to both natural climate forcing and human impact. Its evolution since the last deglaciation is well-documented in sediments from the Baltic Sea itself, as well as in surrounding terrestrial environmental archives. Existing studies point to substantial environmental variability with strong spatial gradients working on inter-annual to millennial time-scales, triggered by a complex interplay of internal and external forcing mechanisms.Despite the diversity of existing paleoenvironmental information, a comprehensive understanding of the Holocene development of the coupled marine-terrestrial Baltic ecosystem is still limited. Main causes are a wide temporal and spatial range of forcing mechanisms and different timings, magnitudes and thresholds of proxy responses in different types of environmental archives. The BaltRap network aims at integrating marine-, annually laminated (varved) lake sediment and tree ring records from the southern Baltic realm for a comprehensive understanding of archive-specific proxy responses to short and long-term climate variations and oscillations as well as the distinction of natural variability from the increasing human impact, at up to the highest possible 'seasonal' resolution.However, since BaltRap focusses on the southern Baltic region, a complete understanding of Circum-Baltic ecosystem responses requires a northward extension of the approach based on varved lake sediment and tree ring records from the Scandinavian Peninsula. This is vital since the northern Baltic realm experienced a substantially different climatic and human development, compared to the South. Moreover, multi-archive investigations of leads and lags of proxy responses necessitate a climate-independent synchronization of the considered archives, minimizing individual chronological uncertainties. Within this proposal, we aim at establishing new seasonally resolved Holocene proxy records of climate and human activity using varved lake sediment and tree ring records from Lake Kälksjön and its catchment (central Sweden), to distinguish the unique Scandinavian influence on the Circum-Baltic ecosystem and extend the BaltRap approach northward. We apply the novel 10Be synchronization tool for a precise synchronization of the Scandinavian Lake Kälksjön record to the existing southern Baltic marine and varved lake sediment archives. Ultimate goal of the research is the first investigation of environmental gradients in the Baltic region during the Holocene based on synchronous multi-archive proxy records. The work will improve our understanding of temporal and spatial ecosystem responses to climatic and human forcing on a new transbaltic North-South transect and provides a step towards a more comprehensive knowledge of Circum-Baltic environmental dynamics, helping to better anticipate future 21st century change.