Geochemical records of paleoenvironmental change in Northwest North America from fossil plant waxes, volcanic glass and tree-rings

北极地区的气候变暖速度快于地球其他地区，目前正在进行的相关环境变化(例如，冰川融化、永久冻土融化释放的碳、北方扩张)预计将放大变暖趋势，其影响将在全球和北方社区感受到。关键是要对北极气候系统有深入的了解，以便能够准确预测未来的变化，并用来指导可能受到影响的自然资源和社区的合理政策决策。过去的气候数据为气候动力学提供了有价值的见解，但北部地区的历史记录稀少而简短。或者，诸如树木年轮和沉积物记录等自然指标记录了过去与今天一样温暖或比今天更温暖的持续时间间隔，并提供了一套令人信服的证据，描述了未来更温暖的世界可能是什么样子。这项拟议中的研究将利用植物化石蜡和火山灰中的稳定氢同位素作为过去温度的代用品，有助于增进对北美西北部过去约1800万年来气候的了解，包括育空和阿拉斯加的部分地区。拟议的研究还将测试一种新的树轮汞(汞)替代品及其跟踪大气汞最近变化的能力，以及它与气候在长时间尺度上的关系，并对未来气候情景下自然生态系统中汞和甲基汞(有毒形式)的建模产生影响。这项拟议的研究承诺对北美西北部独特的自然档案进行严格的多代理分析，以填补近几个世纪到数百万年来关于气候和环境变化的长期知识空白。这一方法将解决有关北极气候系统、区域动态和气候敏感性的基本问题。所获得的见解将极大地提高我们预测未来变化以及对北部社区和基础设施的影响的能力。

Climate warming in Arctic regions is fast outpacing the rest of the planet, and associated environmental changes now underway (e.g., ice loss, carbon release from thawing permafrost, boreal expansion) are expected to amplify warming trends with impacts that will be felt globally, and in northern communities. It is critical to develop advanced understandings of the Arctic climate system so that future changes can be accurately predicted, and used to guide sound policy decisions for natural resources and communities that may be impacted. Past climate data offers valuable insights on climate dynamics, but historical records are sparse and short in northern regions. Alternatively, natural proxies such as tree-rings and sediment records document past warm periods that were as warm as or warmer than today for sustained intervals, and provide a compelling suite of evidence describing what a future, warmer world might look like. The proposed research will help to advance knowledge of past climate over the last ca. 18 million years in N.W. North America, including parts of Yukon and Alaska, using stable hydrogen isotopes in fossil plant waxes and volcanic ash as proxies for past temperature. The proposed research will also test a new tree-ring mercury (Hg) proxy and its ability to track recent changes in atmospheric Hg, and its relation to climate over long timescales, with implications for modelling Hg, and methyl-Hg (toxic form) in natural ecosystems under future climate scenarios. The proposed research promises a rigorous, multi-proxy analysis of unique natural archives in Northwest North America to fill long-standing knowledge gaps on climate and environmental change over recent centuries to millions of years. This approach will address fundamental questions about the Arctic climate system, regional dynamics and climate sensitivity. Insights gained will greatly improve our ability to anticipate future changes, and impacts to northern communities and infrastructure.