Permafrost archives of northern environmental change and permafrost landsystems of the Mackenzie valley

气候变化对加拿大北部永久冻土景观的长期影响将是21世纪的一个决定性问题。我们在减少集体向大气排放温室气体方面进展甚微，气候变暖的影响正在迅速超过几乎所有陆地第四纪的类似影响。对于北方的景观和社区，我们必须开发更好的工具，为未来的解冻做准备。今天，北极西部受影响最严重的地区与埋藏的冰川冰有关，这些冰川冰在过去的一万年中已经被遗弃，但现在正在变暖，并且在区域尺度上变得容易融化。这种地表冰的分布反映了第四纪冰川作用的动态和原冰缘附近冰的埋藏。同样，整个加拿大北部的地冰性质反映了最近的地质历史及其与过去植被和气候的相互作用。这些历史偶发事件的相互作用确定了区域永久冻土景观单元或土地系统，这将确定未来的响应模式。了解其他区域的融化轨迹将取决于类似的区域第四纪地质遗产，这些遗产强烈影响了地面冰的分布和特征。在大陆尺度上存在未来气候变化对永久冻土影响的模型，但这些模型的准确性受到我们对地面冰的性质和分布的理解的限制，这在很大程度上决定了地区对融化的敏感性。本研究的目的有三个：(1)详细描述麦肯齐河谷的景观历史、晚更新世快速消冰的影响和由此产生的地貌；(2)在区域范围内，通过野外测绘建立这些特征，为未来麦肯齐河谷中部和南部的融化景观提供模型；(3)利用CT扫描和伽马密度等新工具开发和测试永冻层表征的新方法，这些新工具可以对永冻层岩心进行无损表征。这项工作需要在麦肯齐山谷进行多个夏天的实地考察。

The longterm impact of climate change on the permafrost landscape of northern Canada will be a defining issue in the 21st century. We have made little progress in decreasing our collective greenhouse gas emissions to the atmosphere, and the impacts of a warming climate are quickly exceeding nearly all of our terrestrial Quaternary analogues. For northern landscapes and communities, we must develop better tools to prepare for future thaw. Today, the most severely affected areas of the western Arctic are associated with buried glacier ice that has been relict for the last 10,000 years, but is now warming and becoming thaw susceptible at regional scales. This distribution of ground ice reflects the dynamics of glaciation and the burial of ice near the former ice margin in the Quaternary. Similarly, ground ice properties throughout northern Canada are a reflection of the recent geologic history and its interaction with past vegetation and climate. The interactions of these historical contingencies define regional permafrost landscape units, or Landsystems, that will define patterns of future response. Understanding other regional trajectories of thaw will depend on similar legacies of regional Quaternary geology that have strongly influenced the distribution and character of ground ice. Models exist at continental scales for future climate change impacts on permafrost, but the veracity of these models is limited by our understanding of the nature and distribution of ground ice, which in large part, will determine the susceptibility of areas to thaw. The objectives of this research are threefold: (1) to detail the landscape history of the Mackenzie valley, the impact of rapid deglaciation and resulting landforms during the late Pleistocene; (2) to establish these properties, regionally, through field mapping to provide a model for future thaw landscapes of the central and southern Mackenzie valley; and (3) develop and test new approaches to permafrost characterization using new tools such as CT scanning and gamma density that allow the non-destructive characterization of permafrost cores. This work requires multiple summers of fieldwork in the Mackenzie valley.