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。我们在减少对大气的集体温室气体排放方面进展甚微，气候变暖的影响正在迅速超过我们几乎所有的陆地第四纪类似物。对于北方的景观和社区，我们必须开发更好的工具，为未来的融化做准备。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1万年里一直残留，但现在正在变暖，在区域范围内变得容易融化。这种地表冰的分布反映了第四纪前冰缘附近的冰川作用和冰的埋藏动力学。同样，整个加拿大北部的地面冰特性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决定了区域永久冻土景观单位或土地系统，这将决定未来的反应模式。对其他区域融化轨迹的理解将取决于区域第四纪地质的类似遗产，这些遗产对地面冰的分布和特征产生了强烈影响。关于未来气候变化对永久冻土的影响，已有大陆尺度的模型，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，这在很大程度上将决定该地区融化的敏感性。这项研究的目标有三个方面：(1)详细说明麦肯齐河谷的景观历史、快速冰川消融的影响以及晚更新世期间的地形；(2)通过实地测绘在区域上建立这些特性，为麦肯齐河谷中部和南部未来融化的景观提供模型；以及(3)利用CT扫描和伽马密度等新工具开发和测试新的永冻层表征方法，使之能够对永冻岩芯进行无损表征。这项工作需要在麦肯齐山谷进行多个夏天的田野工作。

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.