CGRG Bibliography of Canadian Geomorphology
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Author : Demuth, M.N.; and Keller, R.
Date : 2002.
Title : An assessment of the mass balance of Peyto Glacier (1966-1995) and its relations to recent and past-century climatic variablity.
Publication : Peyto Glacier-Once Century of Science,. Edited by: Demuth, M.N., Munro, D.S. and G.J. Young. National Hydrology Research Institute Science Report
Issue : 8:
Page(s) : 83-132.
Abstract
The variation of the seasonal and net mass balance time series of Peyto Glacier, 1966-1995, is described. Analysis reveals that the Winter balance played a dominant role in the evolution of the net balance for this period. A major shift in the Winter balance is identified to have taken place after 1976, exhibiting a quasi-step change of approximately -515 mm w.e. More recent evidence from Peyto Glacier and other related snow pack studies point to a gradual attenuation of this pattern after 1988 with Winter accumulations gradually returning to their long-term average. The Summer balance, though less important overall, manifested some of the most extreme mass losses for the glacier. The net mass balance exhibits a normal of approximately -495 mm w.e. a -1 . Several independent measures of mass balance, such as those based on RADAR ice-thickness soundings and terrestrial mapping surveys, converge on the respective normal values determined from standard mass balance measurements. The association of these observations with shifts in synoptic climate is established through available data describing the variation of sea surface temperature, atmospheric circulation, seasonal snow and perennial ice. The mid-1970s shift to lower Winter balance is synchronous with an increase in the frequency of non-snow producing synoptic weather types and a decrease in the frequency of snow producing weather types as influenced by a modulation of the Pacific-Decadal-Oscillation, the El Niņo Southern Oscillation and their influence on the Pacific-North-American atmospheric circulation pattern. The strong spatial and temporal coherence of anomalous patterns in the availability of seasonal snow and the mass balance of alpine glaciers and their relation to ocean-atmosphere phenomena is encouraging. Such knowledge should assist in the development of better forecasting tools for use in water resource management under scenarios of climate variability. At the historical scale, the relative past-century change of the energy associated with glacier melting at Peyto Glacier is described using historical mass change estimates and recent inter-annual mass balance data. In agreement with the general global pattern, Peyto Glacier undergoes spectacular mass loss during the first half of the 20th Century followed by a pronounced abatement after the mid-century. More recently, particularly since the mid-1970s, the rate of mass loss approaches that of the early century, even showing signs of acceleration broadly consistent with estimated man-induced radiative forcing (several W/m 2 ). Interestingly, the drastic early-century variations took place during relatively weak anthropogenic forcing. Overall, analysis reveals that Peyto Glacier has lost approximately 70% of its volume since the first direct observation of its extent by W. Wilcox one-century ago.
Bibliography of Canadian Geomorphology