The Geomorphic Response of Glaciers to Climate Change in the American Cordillera

冰川是气候变化的敏感指标；它们也是地球水文循环的重要组成部分。对冰川及其沉积物的仔细研究为过去的气候变化事件提供了重要的参考。在几十年到几个世纪的时间尺度上，关于气候变异性的规模、来源和空间模式，以及这种变异性在人为变暖之前如何影响冰川，仍然存在激烈的争论。在接下来的五年里，我的研究生、合作者和我将：1)评估加拿大西部和最南端巴塔哥尼亚地区晚全新世冰川推进的同步性；以及1b)限制加拿大西部高纬度地区全新世高潮推进的时间和空间模式。我们将使用陆地核素测年(TCN)在现有测年方法不适用和对过去冰川活动知之甚少的地区(育空地区的墓碑山和佩利山，西北地区的拉格朗日山脉和麦肯齐山)建立冰川历史。来自加拿大和巴塔哥尼亚的准确和精确的冰川年表将阐明美洲高纬度地区世纪气候变化事件的时间、幅度和空间范围。记录这些事件是朝着更好地了解百年尺度的气候动力学及其对温带外冰川的影响迈出的重要一步。冰川也是山区景观中的重要侵蚀因素，但由于大多数当代监测项目的短期偏差，以及当代冰川下方和邻近地区沉积物的重新加工，量化冰川在景观演变中的有效性--通常是根据泥沙产量测量得出的--是困难的。我们的目标是通过清点高山冰川附近的几个集水区、冰川沉积物和湖泊盆地中包含的冰川产生的沉积物的体积，来计算全新世时间尺度上的沉积物侵蚀，从而减少这些偏差。我们还将开发区域到全球的泥沙产量数据集，将卫星图像显示的冰川湖泊地表水的光谱特征与其季节性至年累积率联系起来。因此，在第二个主题下，我们将：2a)通过结合使用遥感技术和对湖泊沉积岩心的分析来估计当代冰川集水区的沉积物产量；2b)使用直升机安装的激光雷达、舰载多波束声纳和雷达设备来估计冰川盆地中沉淀源(冰川前场、前冰川洪泛平原)和汇(前冰川三角洲和湖底)的体积和最近的质量变化；以及2c)利用从最近冰川消融的冰缘内的石英基质获得的TCN测年原理(10Be和14C)来评估海洋和大陆背景下的冰川侵蚀速度；2d)探索利用微测年来估计冰川下温带下的冰下沉积物的储量；和2e)使用来自i-v的主要发现来改进和验证冰川侵蚀模型，该模型可运行于整个山脉。加拿大对科学和技术的持续投资对于解决目前和未来气候变化引起的问题至关重要。气候变化、环境退化、水资源和水力发电都是公众关注的问题，很可能成为本世纪广泛研究的焦点。在这项资助的期限内，3名博士生、2名硕士学生和众多本科生将接受地球系统科学、地球测量学和冰冻圈科学方面的专家培训。这些高技能的实习生将为一个强大和富有成效的科学和技术部门做出贡献，这将使加拿大人和加拿大经济受益。

Glaciers are sensitive indicators of climate change; they also represent vital components of Earth’s hydrologic cycle. A careful study of glaciers and their deposits provides important proxies for past climate change events. There remains active debate about the magnitude, origin, and spatial pattern of climate variability at time scales of decades to centuries and how this variability affected glaciers prior to anthropogenic warming. Over the next five years, my graduate students, collaborators and I will: 1) assess the synchronicity of late-Holocene glacier advances in western Canada and southernmost Patagonia; and 1b) constrain the timing and spatial pattern of climactic Holocene advances at high latitudes in western Canada. We will use terrestrial nuclide dating (TCN) to develop glacier histories in regions where existing dating methods are unsuitable and where little is known about past glacier activity (Tombstone and Pelly mountains, Yukon, Ragged Range and Mackenzie Mountains, Northwest Territories). Accurate and precise glacier chronologies from Canada and Patagonia will clarify the timing, amplitude, and spatial extent of century climate change events at high latitudes in the Americas. Documenting these events represents an important step towards improved knowledge of century-scale climate dynamics and its effects on glaciers in the extratropics. Glaciers also represent important erosive agents in mountain landscapes, but quantifying their effectiveness in landscape evolution, often calculated from sediment yield measurements, is hampered by short-term biases of most contemporary monitoring programs and the reworking of sediment beneath and adjacent to contemporary glaciers. Our aim is to reduce these biases by calculating sediment erosion over Holocene time scales by inventorying the volume of glacially-produced sediments contained in several catchments glacier deposits and lake basins near alpine glaciers. We will also develop regional-to-global datasets of sediment yield by relating the spectral characteristics of surface water of proglacial lakes revealed by satellite imagery to their seasonal-to-yearly accumulation rates. Under this second theme, we will thus: 2a) estimate contemporary sediment yields for glacierized catchments through combined use of remote sensing techniques and analysis of lake sediment cores; 2b) use helicopter-mounted LiDAR, vessel-mounted multi-beam sonar, and radar equipment to estimate volume and recent mass change of sediment sources (glacier forefields, proglacial floodplain) and sinks (proglacial delta and lake floor) in glacierized basins; and 2c) employ principles of TCN dating (10Be and 14C) obtained from quartz substrate within recently deglaciated ice margins to assess glacier erosion rates in maritime and continental settings; 2d) explore the use of comminution dating to estimate subglacial sediment storage beneath temperate glaciers; and 2e) use major findings from i-v to refine and validate glacier erosion models which can be run for entire mountain ranges. Continued investment by Canada in science and technology is essential to solve problems that arise from present and future climate change. Climate change, environmental degradation, water resources, and hydroelectric power generation are issues in the public spotlight and are likely to be the focus of extensive research throughout this century. Over the duration of this grant, 3 PhD students, 2 MSc students, and numerous undergraduate students will be trained as experts in earth system science and geomatics, and cryospheric sciences. These highly skilled trainees will contribute to a strong and productive science and technology sector that will benefit Canadians and the Canadian economy.