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

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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.