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Documenting recent environmental changes and their impact in
the Canadian Rockies
Brian Luckman, University of Western Ontario, Canada
Abstract: This presentation will discuss
the evidence for and nature of environment changes in the Canadian
Rockies over the last few centuries and present examples of the
impact on selected natural environments. Available instrumental
climate data indicates an increase of approximately a 1.5C
increase in mean annual temperatures over the last 100 years.
However, during this period increases in winter temperatures have
been more than twice as large as those during spring and/or summer
and minimum temperatures are rising significantly faster than mean
or maximum temperatures. Glacier cover has decreased by at least
25% during the present century and glacier fronts have receded to
positions last occupied ca. 3000 years ago. These two lines of
evidence suggest that the climate of the late 20th century is
exceptional in the context of the last 1000 to 3000 years.
Detailed studies in three closely located upper treeline sites
document variable responses of vegetation to climate change that
reflect species differences as well as local differences in
microclimate and site conditions. Treeline has advanced upslope in
response to climate warming, but site and species differences
control the rate and nature of the advance. Human impacts on the
environment compound the changes due to climate warming. Historic
photographs indicate significant changes in the type and density
of forest cover due to the absence of significant forest fires
within these National Parks during the last 70-80 years. The
visual impact of these changes, which partially reflect a policy
of fire suppression, is far greater than those associated with
more direct tourist-related impacts. It is therefore important
that monitoring programmes examine vegetation changes over the
entire landscape rather than focussing exclusively on supposedly
climate-sensitive sites.
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