Glaciers
Editor’s Note: How do we observe and analyze the change to our glaciers, and why are these changes important to us and our alpine environment?
Mike Demuth shows us trends and glacial recession that are hallmarks of climate change and what we can expect for the future.
This article first appeared in the ACC's 2018 State of the Mountains Report. We'll continue to publish articles exploring the science on our current state of Canada's alpine on our blog throughout the year. Find them all here.
Author working on the plateau of the Columbia Icefield
Canada’s contemporary glacier cover is found almost exclusively in temperate and Arctic mountain environments. Outside of the ice sheets of Antarctica and Greenland, Canada has more glacier cover than any other nation — some 200,000 square kilometres — one quarter of which is found in the mountain west including Vancouver Island and the remainder in the Canadian Arctic Archipelago.¹ There are also small glaciers in northern Labrador.
Climate change and changing glaciers
• Cumulative annual front variation observations:
- dark blue for maximum extents (+2.5 km)
- dark red for minimum extents (–1.6 km)
- all relative to the extent in 1950 as a common reference (i.e. 0 km in white)
• Ratio of advancing glaciers:
- white for years with no reported advances
- dark blue for years with a large ratio of advancing glaciers
- periods with very small data samples are masked in dark grey
- figures are based on all available front variation observations and reconstructions excluding absolute annual front variations larger than 210 m / year to reduce the impression of calving and surging glaciers
Figure 1: Left panel: seasonal and annual mass balances for reference monitoring glaciers in North America with Pearson correlation coefficients indicating the relative role of Summer versus Winter conditions; Right panel: summary of glacier front variations relative to their position in 1950 and the ratio of advancing versus retreating glaciers. Front variations greater than 210 m/year were excluded to reduce the influence of calving and surging glaciers. After Zemp and the National Correspondents to the World Glacier Monitoring Service, 2015 [ref. 2]
The professional observation and analyses of glacier fluctuations usually concerns itself with glacier mass change because seasonal and annual mass changes are a direct result of changing precipitation, air temperature and cloudiness — that is, weather and climate. Most casual observers, however, will readily note changes in the dimensions and extent of the glacier after the delayed and complex process of dynamic readjustment to mass changes; if conducted over long enough intervals over which the effect of the dynamics is filtered out, are also excellent indicators of the cumulative effects of climate change.
A recent landmark study considering the fluctuation of reference monitoring glaciers around the world concludes, in part, that “The rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed [more than a century] and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong [negative] imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable”.² Numerous glaciers in Canada are part of this internationally coordinated effort. Several recent site and regional analyses confirm the matter that Canada’s glaciers are in a state of negative mass imbalance fuelling unprecedented glacier deflation generally and that both winter and summer conditions contribute to specific responses (Figure 1).³ ⁴ ⁵ ⁶ There is also evidence that year-to-year variability is increasing in some regions.⁷ For example, within the span of a decade (2007-2017), many glaciers in western Canada experienced record mass gains one year, record losses several years later and, most notably, by 2017, many glaciers and icefields lost all or nearly all of the accumulated firn pack in their upper reaches — in effect, new ice was not being generated.
Why glaciers are important
As is true for the vast majority of glaciers worldwide, the Peyto Glacier in Banff National Park has been retreating rapidly, especially since the last half of the 20th century, and has reportedly lost 70% of its mass since it was first measured. Photo: Ian Holmes
The presence of glaciers influences a wide variety of natural processes and mountain heritage attributes.⁸ Foremost is their provision of water and aquatic services, particularly when other seasonal sources of water are in decline (snowmelt) or absent outright (rain). Glacier runoff and its promotion of often severe hydraulic conditions aids in the development and maintenance of habitat for numerous aquatic species adapted to cold, turbulent waters.⁹ Glaciers provide travel corridors for wildlife, connecting regions that are seasonally sought out for preferential habitat and climate conditions. For humans, glaciers also provide vantage points for exploration, access to technical mountaineering terrain, and interlaced high level ski and walking corridors.
Their contemporary decline with reference to Holocene variability, and in terms of both mass, thickness and area-wise extent, is considered a hallmark indicator of climate change with wide-ranging impacts. In the Rocky Mountains, for instance, water resource and ecosystem integrity considerations must contend with the loss of Little Ice Age “bonus water” which may have given the impression of water “abundance” during the early 20th century; and in the Canadian Arctic Archipelago, recent mass losses have contributed more to global sea-level rise than that attributed to the wastage of the Greenland ice sheet over the same period.¹ ⁴ ⁸ ⁹ ¹⁰ ¹¹ ¹²
With reference to recent modelling efforts projecting sobering glacier contraction in western Canada by the close of this century, it is noted that “Mountains are monuments to what water can make”.¹³ ¹⁴
Mike Demuth is a Professor at the Centre for Hydrology at the University of Saskatchewan.
References:
1 Demuth, M.N., 2012. Becoming Water - Glaciers in a Warming World. A Rocky Mountain Books Manifesto. 135 p. ISBN 9781926855721
2 Zemp, M. and 37 others*, 2015. Historically unprecedented global glacier decline in the early 21st century. Journal of Glaciology 61(228): 745-761 doi: 10.3189/2015JoG15J017 (*World Glacier Monitoring Service)
3 Demuth, M.N., V. Pinard, A. Pietroniro, B.H. Luckman, C. Hopkinson, P. Dornes, and L. Comeau, 2008. Recent and past-century variations in the glacier resources of the Canadian Rocky Mountains–Nelson River system. Terra Glacialis, Special Issue: Mountain Glaciers and Climate Changes of theLast Century, L. Bonardi (Ed). p.27–52.
4 Marshall, S.J., E.C.White, M.N. Demuth, T. Bolch, R. Wheate, B. Menounos, M.J. Beedle and J.M. Shea, 2013. Glacier water resources on the eastern slopes of the Canadian Rocky Mountains. Canadian Water Resources Journal 36(2):109-134. DOI:10.4296/cwrj3602823
5 Tenant, C.,B. Menounos, R. Wheate and J.J. Clague, 2012. Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006.The Cryosphere 6:1541-1552. https://doi.org/10.5194/tc-6-1541-2012
6 Gardner, A.S., G. Moholdt, B.Wouters, G.J. Wolken, D.O. Burgess, M.J. Sharp, J.G. Cogley, C. Braun and C. Labine, 2011. Sharply increased mass loss from glaciers and icecaps in the Canadian Arctic Archipelago. Nature. Published online April 20, 2011. doi:10.1038/nature10089
7 Demuth, M.N. and G. Horne, 2017. Decadal-centenary glacier mass changes and their variability, Jasper National Park of Canada, Alberta, including the Columbia Icefield region; Geological Survey of Canada, Open File 8229,32 p. https://doi.org/10.4095/304236
8 Demuth, M.N. and M. Ednie, 2016. A glacier condition and thresholding rubric for use in assessing protected area / ecosystem functioning; Geological Survey of Canada, Open File 8031, 53 p. https://doi.org/10.4095/297892
9 Petts, G.E., A.M. Gurnell, and A.M. Milner, 2006. Ecohydrology: New opportunities for research on glacier fed rivers. In - Peyto Glacier: One Century of Science, M.N. Demuth, D.S. Munro, and G.J. Young (Eds). NHRI Science Report Series 8, Environment Canada, National Hydrology Research Institute, Saskatoon, Saskatchewan, p.255–275. ISBN 0660176831
10 Personal communication, 1997. Robert Halliday, Director, National Hydrology Research Institute- on the significance of 20th century glacier mass loss in the eastern slopes of the Canadian Rocky Mountains.
11 Sauchyn, D., M.N. Demuth and A. Pietroniro, 2009. Upland Watershed Management and Global Change–Canada’s Rocky Mountains and Western Plains. Chapter 3 in - Part I Mountain and Upland Areas, Managing Water Resources in a Time of Global Change - Contributions from the Rosenberg International Forum on Water Policy. A. Garrido and A. Dinar (Eds). Routledge. 228 p. ISBN 9780415777780
12 van Wychen, W., D.O. Burgess, L. Gray, L. Copland, M. Sharp, J.A. Dowdeswell, and T.J. Benham, 2013. Glacier velocities and calving lux from the Queen Elizabeth Islands, Nunavut Canada. Geophysical Research Letters 41: 484-490. DOI:10.1002/2013 GL058558 Cont.#20130293.
13 Clarke, G.K.C., A.H. Jarosch, F.S. Anslow, V. Radic and B. Menounos, 2015. Projected deglaciation of western Canada in the twenty-first century. Nature Geoscience 8:372–377. doi:10.1038/ngeo2407
14 Sandford, R.W., 2017. Our Vanishing Glaciers - The Snows of Yesteryear and the Future Climate of the Mountain West. Rocky Mountain Books. 223 p. ISBN 978-1-77160-202-0