Climate Change and the Rocky Mountains - Impact of Global Changes on Mountains: Responses and Adaptation - page 454

and modify the composition of macro invertebrate communities. Didymo
is currenlty present in an estimated 64% of streams in Glacier National
Park (GNP). Didymo's abundance is positively related to summer stream
temperatures in GNP, which are likely to continue increasing over the
coming decades, thereby increasing the extent and severity of didymo
blooms (Schweiger et al. 2011). Didymo may be a useful indicator of thermal
and hydrological modifi cation with climate warming across the Rocky
Mountain region.
North Saskatchewan River
Snowpack from watersheds on the eastern slopes of the Canadian Rocky
Mountains is an important source of water for the western prairie provinces
of Alberta, Saskatchewan and Manitoba (Schindler and Donahue 2006).
The North Saskatchewan basin is important because it is subject to the
1969 Master Agreement on Apportionment, which dictates that Alberta
must allow 50% of the annual natural flow to enter the province of
Saskatchewan, while maintaining minimum in-stream fl ow requirements
(North Saskatchewan Watershed Alliance 2005). This presents a challenge
for water managers because reservoir operations on the upper North
Saskatchewan are at risk as a result of decreased reservoir reliability under
future climate change (Minville et al. 2009, Minville et al. 2010).
MacDonald et al. (2012) demonstrated that snow accumulation and
ablation in the North Saskatchewan basin are sensitive to climate change.
Climate warming is likely to result in an upward shift in elevation of the
zero degree isotherm, with a transition to more precipitation occurring as
rain than snow annually. The average maximum SWE is not likely to change
substantially under future conditions because winters will remain cold.
However, the timing of spring snowmelt onset is likely to change under a
range of future climate scenarios (Fig. 20.8). An earlier snowmelt onset over
large portions of the North Saskatchewan basin will likely reduce late season
water availability for humans and ecosystems. Reductions in available water
will force adaptive management strategies to be implemented in order to
avoid negative consequences for water users.
Adaptive Management in the Rocky Mountains
Comprehensive assessments of regional and local climate trends and
trajectories will be integral for assessing potential impacts of climate
warming in Rocky Mountain ecosystems (Pederson et al. 2010). The single
largest source of uncertainty is simply how much and how fast the Earth's
climate will warm. Additional inconclusiveness exists about how large-
scale changes in the atmosphere will be realized at regional and local scales.