Northern Climate Change Schools Program
Lesson Plan

Background Information -
The Impact Climate Change will have on Avalanche Activity

Recent climate change and catastrophic geomorphic processes in mountain environments.

Author: Evans, S.G.; and Clague, J.J.
Publication: Geomorphology 10(1-4): 107-128. 1994

Climatic warming during the last 100-150 years has resulted in a significant glacier ice loss from mountainous areas of the world. Certain natural processes which pose hazards to people and development in these areas have accelerated as a result of this recent deglaciation. These include glacier avalanches, landslides and slope instability caused by glacier debuttressing, and outburst floods from moraine- and glacier-dammed lakes. In addition, changes in sediment and water supply induced by climatic warming and glacier retreat have altered channel and floodplain patterns of rivers draining high mountain ranges. The perturbation of natural processes operating in mountain environments, caused by recent climatic warming, ranges from tens of decades for moraine-dam failures to hundreds of years or more for landslides. The recognition that climatic change as modest as that of the last century can perturb natural alpine processes has important implications for hazard assessment and future development in mountains. Even so, these effects are probably at least an order of magnitude smaller than those associated with late Pleistocene deglaciation ca. 15,000 to 10,000 years ago.

The impact of climate change on catastrophic geomorphic processes in the mountains of British Columbia, Yukon and Alberta.

Author: Evans, S.G.; and Clague, J.J.
Publication: 1997. Responding to Global Climate Change in British Columbia and Yukon. Volume 1 of the Canada Country Study: Climate Impacts and Adaptation. Edited by: E. Taylor and B. Taylor. British Columbia Ministry of Environment Lands & Parks and Environment Canada, Vancouver (also on-line at

Catastrophic geomorphic processes in mountain terrain are heavily influenced by climatic factors. As a result, the occurrence of these processes, which include landslides and outburst floods, is sensitive to climate change. In the Canadian Cordillera, the analysis of historical data and a limited number of cases, suggest that under conditions of possible increased precipitation in future climate change, the frequency of debris flows and other landslide types will increase. As in the past, these events should be expected to impact on settlements, infrastructural elements, resources and the environment, resulting in human and financial losses. Long term temperature change affects the volume of glacier ice in mountain regions. Glacier ice loss due to global warming has been identified as an important factor in the occurrence of a range of catastrophic processes, such as outburst floods and rock avalanches. With respect to predicted temperature increases, further glacier ice loss will result in continued debutressing of mountain slopes leading to slope deformation and, in some cases, catastrophic failure. The potential impact of rock avalanches should therefore be considered in the development of areas adjacent to and downstream of present-day glaciers. With continued warming, the frequency of outburst floods will reach a peak and subsequently decrease as the naturally-damned reservoirs decrease in number and size. The nature of mountain permafrost in the Canadian Cordillera is not well known. This is an important gap in view of recent European work linking major rock avalanches and debris flows with the decay of mountain permafrost during recent warming. The further decay of permafrost in northern areas as a result of continued warming trends is likely to increase the occurrence of thaw-flow slides and other types of landslides. Locally, forest fires will amplify this effect.

Geomorphological processes in alpine areas of Canada: the effects of climate change and their impacts on human activities.

Author: Ryder, J.M.
Publication: 1998. Geological Survey of Canada, Bulletin 524: 44 p

Geomorphological processes are related to climate in a complex manner. Estimates of how processes will react to anticipated climate changes, such as warming and increased precipitation, are necessarily tentative and qualitative. They indicate the kinds of changes that may occur in the alpine landscapes, but not the magnitude or precise rates of such changes. If climate change proceeds as forecast, then one of the most apparent results will be a rise in the timberline. This will result in a decrease in the extent of the alpine zone, thus altering the appearance of many mountain areas and their potential for recreation and tourism. Anticipated changes in snowfall include reduced snow and increased winter rain at elevations close to the present winter snowline, and increased snowfall on higher and colder mountains. This will have a detrimental effect on ski resorts at low elevations, but improve winter access for other activities. Warmer summer temperatures will probably lead to a rise in the summer snowline and significant loss of glaciers, changing the scenery in southern mountain areas, such as Banff and Jasper national parks. Climate change will probably have some hazardous effects. Melting of permafrost and more intense rainfall may initiate or increase the frequency of slides and debris flows in some areas. Heavier snowfall may increase avalanche danger, and glacier recession will probably result in more floods and debris flows due to failure of glacier and moraine dams. Increased sediment input to glacier-fed rivers may lead to increased channel instability, erosion, and flooding. The hazard zones related to most of these fluvial processes will extend a long way beyond the limits of the alpine zone. Thinner snowpacks, rapid spring runoff, and a reduced extent of permanent snow and ice will reduce both the seasonal and longer term capacity of alpine areas. This effect could lead to serious water shortages in regions such as the Okanagan Valley, British Columbia.

Global distribution of snow avalanches and changing activity in the Northern Hemisphere due to climate change.

Author: Glazovskaya, T.G.
Publication: 1998. Annals of Glaciology 26(-): 337-342.

Snow avalanches occur in the mountains of all continents and climatic zones. The lower boundary of avalanche distribution rises from sea level in polar and temperate zones to 6000 m in the tropics. Four altitudinal belts of avalanching are distinguished: I) permanent snow; II) stable seasonal snow cover; (III) unstable snow cover; and IV) rare snowfalls. Most avalanche-danger areas of the world belong to the stable seasonal snow-cover belt. Using data from a GFDL Q-flux Model, we estimated possible changes of the main characteristics of the avalanche regime in the Northern Hemisphere: depth of snow cover, duration of the avalanche-prone period and number of days with avalanche-prone snowfalls. At the beginning of the twenty-first century, there will likely be a smoothing of the sharp differences in avalanche activity between various mountain regions of the World. Avalanche activity should be less in the most active regions and it is likely to increase in regions with low avalanche activity.


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