Projected Climate Change and Variability and Their Impact on the Canadian Rocky Mountains - Impact of Global Changes on Mountains: Responses and Adaptation - page 408

“Mountains are important sources of water, energy, minerals, forests
and agricultural products and areas of recreation. They are storehouses
of biological diversity, home to endangered species and an essential
part of the global ecosystem.”
(UN Earth Summit 1992)
The projected warming of the climate will impact various aspects of the
mountain environment, such as on hydrological cycle involving changes
in glaciers and snow, ecosystem biodiversity and species distribution, and
natural hazards such as landslides. Changes in these natural environmental
conditions in response to climate change and variation will then impact
on human health, settlements, food security and other socio-economic
activities, not just within the mountainous regions but also in regions
affected by the changes in the hydrological cycle in the mountains. But
where, how and by how much these changes will occur is uncertain because
of the existence of many local microclimate regimes caused by the complex
mountainous topography.
Glacial retreat and thinning
One of the most visible impacts of climate warming is the gradual decrease
in the size of the existing glaciers. Although there are not comprehensive
glacier inventory data for the Canadian Rockies, Luckman (1998) suggests
that the existing data indicate an average loss of about 25% in area during
the 20th century. He notes that the “data make no allowance for glacier
thinning and therefore may considerably underestimate volumetric loss”
(Luckman 1998). The loss is infl uenced by changes in both temperatures
and precipitation. Although the precipitation data suffer from spatial and
temporal, but mostly spatial, limitation in the Rockies, they show decadal
variations (infl uenced by the low-frequency variability modes, such as the
Pacifi c-North America (PNA) Oscillation caused by ENSO), peaking in
the mid-20th century (Shabbar et al. 1997). In general terms, Oerlemans
and Fortuin (1992) showed that the sensitivity of glacier volume changes
to temperature is a function of precipitation. Using seasonal and annual
mass balance measurements, Dyurgerov (2003) showed increases in both
summer and winter glacier balances are related more to temperature and
precipitation, respectively. These increases suggest that the hydrological
cycle is being intensifi ed by glaciers.
A relatively more recent and comprehensive analysis and discussion of
changing glacier characteristics in western North America under climate
change, and the impact on the hydrology, geomorphic hazards and stream
water quality due to retreating and melting glaciers was carried out by
Moore et al. (2009). The authors have noted that the recent glacial retreat