Modelling Glacier and Ice Sheet Response to Climate Change

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My research group combines field studies and numerical modelling to study glacier dynamics and glacier-climate processes. My main aim is to improve the understanding of glaciers and ice sheets in the climate system and their representation in glaciological and climate models. Field sites include western and Arctic Canada, Iceland, and Greenland, and my modelling work is across a range of spatial and temporal scales, from mountain glacier response to climate change to the evolution of Ice Age ice sheets and climate dynamics. *** *The proposed research over this Discovery Grant cycle contains each of these different research threads, but will focus on meltwater drainage, refreezing, and retention in the accumulation area of mountain icefields in western Canada and the Greenland Ice Sheet, where firn underlies the seasonal snow. Meltwater refreezing and liquid water storage in firn aquifers give internal accumulation, retaining mass within the system and reducing glacier runoff. This process is generally not represented in models of glacier and ice sheet response to climate change, despite growing evidence that firn processes need to be understood for accurate modelling of glacier mass balance, meltwater runoff, and sea level rise. Moreover, meltwater retention and refreezing impact firn density, which needs to be known to interpret airborne and satellite altimetry data that are used to monitor glacier and ice sheet change. The proposed research targets the thermodynamic and hydrological controls of meltwater retention and its implications for glacier thermal regime, densification, glacier mass balance, meltwater runoff, and isotope stratigraphy. *** *Field studies will be conducted at Dye2 in southern Greenland, the upper Kaskawulsh Glacier in the St. Elias Mountains, Yukon, and the Columbia and Illecillewaet Icefields in western Canada. One to two field seasons are anticipated at each site, to acquire shallow ice cores (up to 50 m depth) and study meltwater percolation and refreezing in the near-surface pits (up to 5 m depth) excavated in the seasonal snow and firn. The pits will be instrumented with thermistors and time-domain reflectometry (TDR) probes, to track snow/firn liquid water content and the thermal signal of latent heat release as meltwater refreezes. The ice cores will provide a deeper representation of meltwater percolation and ice layer content. Little is known about the depth and properties of firn in western and northern Canada. These studies will offer primary data into firn characterization, which will guide the development of a firn model for large-scale icefield and ice sheet modelling. In addition to the firn hydrology and thermodynamics, stable isotopes (d18O, dD) will be analyzed to understand the impacts of meltwater percolation and refreezing on stable isotope stratigraphy and thermometry, in support of ice-core based climate reconstructions.**