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

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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.