Projected Climate Change and Variability and Their Impact on the Canadian Rocky Mountains - Impact of Global Changes on Mountains: Responses and Adaptation - page 409

and/or mass loss are accompanied by statistically detectable declines in late-
summer glacier-fed streams. For example, glaciers located in the northwest
British Columbia and southwest Yukon regions have shown very little
terminal retreat but have experienced mass loss due mainly to thinning,
causing increases in streamfl ows fed by the glaciers in these regions.
Melting of glaciers and permafrost, and precipitation more in the form
of rain instead of snow, will likely cause various natural hazards such as
soil erosion, landslides, debris and mud fl ows (Evans and Clague 1997).
These hazards will pose signifi cant risk to populations living downstream
in the lowland regions.
Impact on hydrological cycle and streamϔlows
Overall, the glaciers in the Canadian Rockies have been retreating
consistently over the last 30 years or so. With negative mass balance and
volume loss, these glaciers will continue to lose ice and shrink. Some
small glaciers have already disappeared, or will soon do so. This situation
will likely accelerate in the future under climate warming, producing a
pronounced variation in the present seasonal fl ow patterns of streams fed
by the glaciers. Loukas et al. (2002), for example, examined what would
happen to the seasonal fl ow pattern of Illecillewaet River in the Columbia
Mountains of British Columbia. By reducing the glacier (water source for
the river) by 1/3 and using a hydrological model driven by climate change
model data for the period 2008 to 2100, they found, relative to the 1970-1990
level, a slight increase in the streamfl ow in spring (May and June) and a
decrease from July to September.
Kienzle et al. (2012) examined how streamfl ow in the Cline River
watershed would change under the IPCC projected increases in
temperatures and precipitation over western Alberta. The Cline River
watershed contributes over 40% of the North Saskatchewan River
streamfl ow at Edmonton, Alberta. About 60% of the mean annual Cline
River streamfl ow comes from snowmelt, while about 8% comes from
glacier melt. Kiengle et al. (2012) found that increases in mean annual
precipitation of about 1.2, 11, and 16.6% would be there in the 2020s, 2050s
and 2080s, respectively, leading to “a clear shift in the future hydrological
regime, … with signifi cant higher streamfl ow between October and June,
and lower streamfl ow in July-September.” Although nearly 70% of the
streamfl ow in the July-September period can come from glacier melt, it
was not included in their streamfl ow estimates due to “current inadequate
simulation of future glacial melt.” Thus it is likely that the July-September
decreases in the streamfl ow are over-estimated. Earlier peak streamfl ow
was found to be caused by the earlier melting of the snowpack (due to
higher spring temperatures), combined with increased spring rainfall.