HYPSOMETRIC ANALYSIS OF GLACIER TERMINUS FLUCTUATIONS: PRELIMINARY RESULTS FROM BYLOT ISLAND, NUNAVUT, CANADA
WALTER, FREDERIC S.A.. University of Calgary.
Williams, Jeffrey L.M.. University of Calgary.
Sjogren, Darren B.. University of Calgary.
Moorman, Brian J.. University of Calgary.
While substantial, the impacts of a rapidly changing climate on fragile northern environments are poorly understood. In particular, the linkages between climate, glacier response and geomorphic activity in areas of glaciated / non-glaciated transition are exceptionally complex. It is often assumed that a change in glacier terminus position represents a response to a change in climate. Although certainly the case in the long term, it is unclear how the dynamics of glaciers cause lagged responses which, in turn, influence the pattern of retreat in the short term. This research project focuses on the fluctuation of glacier terminus positions on Bylot Island, Nunavut, Canada.
Recent investigations on Bylot Island, located off the northeastern shore of Baffin Island in the Eastern Canadian Arctic, determined that--of the 18 glaciers in the study area--10 demonstrated noticeable signs of retreat (i.e. a negative mass balance). Implementation of remote sensing techniques identified that over a 46-year period a single glacier (B28) retreated 1.8 km, while an adjacent glacier (B26) experienced no appreciable retreat (Moorman and Michel 2000). This research project attempts to explain the disparate advance and retreat patterns identified on Bylot Island despite the juxtaposition of similar-sized glaciers in the study area.
The disparate response of glaciers on Bylot Island to changes in climate confuses any attempt to generalize how the glaciers should, or have, responded to climatic events. While some of the variation may be explained by differences in local climate surrounding individual glaciers, Furbish and Andrews (1984), referring to glaciers in general, stated that much of the variation could be attributed to the many morphological and glaciological features that distinguish individual glaciers. These include--but are not limited to--differences in glacier size, steepness, elevation, mass turnover and areal distribution of accumulation and ablation zones. This research examines one way in which valley topography is linked to long-term glacier response through the distribution of a glacier's surface area over elevation (i.e. the glacier's hypsometry) and the distribution of mass balance over elevation.
First introduced by Langbein et al. in 1947, the hypsometric curve describes the distribution of area with elevation. Strahler (1952) extended the idea to include the percentage hypsometric curve and the hypsometric integral. Although historically used in geomorphic analysis of form and process, recent studies by Furbish and Andrews (1984) and Rivera and Casassa (1999) demonstrated the utility of hypsometric analysis in glaciological applications. A synoptic analysis of glacier hypsometry for Bylot Island combined with an approximation of the Equilibrium Line Altitude (ELA) is being used to determine the sensitivity of selected glaciers to changes in the ELA (and thus to changes in climate). Preliminary results from glaciers B26 and B28 will be presented.
Furbish, D.J. and Andrews, J.T. 1984. The use of hypsometry to indicate long-term stability and response of valley glaciers to changes in mass transfer. Journal of Glaciology, 30: 199-211.
Langbein, W.B., and Others. 1947. Topographic characteristics of drainage basins. United States Geological Survey, Water-Supply Paper, 968-C: 125-158.
Moorman, B.J. and Michel, F.A. 2000. The burial of ice in the proglacial environment on Bylot Island, Arctic Canada. Permafrost and Periglacial Processes, 11: 161-175.
Rivera, A. and Casassa, G. 1999. Volume changes on Pio XI glacier, Patagonia: 1975-1995. Global and Planetary Change, 22: 233-244.
Strahler, A.N. 1952. Hypsometric (area-altitude) analysis of erosional topography. Bulletin of the Geological Society of America, 63: 1117-1142.
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