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，相关的环境变化正在进行中（例如，冰损失、永久冻土融化释放的碳、北方扩张）预计将扩大变暖趋势，其影响将在全球和北方社区感受到。关键是要深入了解北极气候系统，以便能够准确预测未来的变化，并用于指导可能受到影响的自然资源和社区的合理决策。过去的气候数据为气候动态提供了有价值的见解，但北方地区的历史记录稀少而短暂。或者，自然代理，如树木年轮和沉积物记录记录过去温暖的时期，与今天一样温暖或比今天更温暖，并提供了一套令人信服的证据，描述未来，更温暖的世界可能是什么样子。拟议的研究将有助于提高对过去气候的认识。1800万年前在北美西北部，包括部分育空地区和阿拉斯加，使用稳定的氢同位素在化石植物蜡和火山灰作为代理过去的温度。拟议的研究还将测试一种新的树木年轮汞替代物及其跟踪大气汞近期变化的能力，以及其与长期气候的关系，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，以填补近几个世纪至数百万年来气候和环境变化方面的长期知识空白。这种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。获得的见解将大大提高我们预测未来变化的能力，以及对北方社区和基础设施的影响。

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.