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

冰川是气候变化的敏感指标，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替代指标。在几十年到几百年的时间尺度上，气候变化的幅度、起源和空间格局以及这种变化在人为变暖之前如何影响冰川，仍然存在着激烈的争论。在接下来的五年里，我的研究生，合作者和我将：1）评估加拿大西部和巴塔哥尼亚最南端的晚全新世冰川进展的同步性;和1b）限制加拿大西部高纬度地区气候全新世进展的时间和空间模式。我们将使用陆地核素测年法（TCN），在现有测年法不适用和对过去冰川活动知之甚少的地区（墓碑山和佩利山、育空地区、崎岖山脉和麦肯齐山、西北地区），研究冰川历史。来自加拿大和巴塔哥尼亚的准确和精确的冰川年表将澄清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世纪尺度气候动态及其对热带外冰川影响迈出的重要一步。冰川也是山区景观中重要的侵蚀因子，但其在景观演变中的有效性的量化（通常通过沉积物产量测量来计算）受到大多数当代监测方案的短期偏差以及当代冰川下方和附近沉积物的改造的阻碍。我们的目的是减少这些偏见，通过计算沉积物侵蚀全新世时间尺度上的冰川产生的沉积物中包含的几个集水区，冰川沉积物和高山冰川附近的湖泊盆地的库存量。我们还将通过卫星图像揭示的冰前湖地表水的光谱特征与其季节至年度累积率之间的关系，开发区域至全球的沉积物产量数据集。在第二个主题下，我们将：2a）通过遥感技术和湖泊沉积物岩心分析的结合使用，估计冰川化流域的当代沉积物产量; 2b）使用船上激光雷达、船上多波束声纳和雷达设备，估算沉积物源的体积和近期质量变化（冰川前区、冰前洪泛平原）和汇（冰前三角洲和湖底）在冰川化盆地; 2c）采用TCN测年原理（10 Be和14 C）从最近冰消冰缘的石英基质中获得，以评估海洋和大陆环境中的冰川侵蚀速率; 2d）探索使用粉碎测年法来估计温带冰川下的冰下沉积物储存量; 2 e）使用第一至第五阶段的主要研究结果来完善和验证可适用于整个山脉的冰川侵蚀模型。加拿大在科学和技术方面的持续投资对于解决目前和未来气候变化所产生的问题至关重要。气候变化、环境恶化、水资源和水力发电是公众关注的问题，可能是整个世纪广泛研究的焦点。在此资助期间，3名博士生，2名硕士生和许多本科生将被培训为地球系统科学和地理信息学以及冰冻圈科学的专家。这些高技能的受训人员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.