Offsetting temperature increases
The impact of warming of 1°C on SWE values over the winter and spring
seasons can be offset by a precipitation increase of 20% for almost all
SWE values in all snow regimes in Reynolds Mountain; however, warming of
2°C or more cannot be offset by increases in precipitation of less than
20%. The sensitivity of SWE in the blowing snow source and sink HRUs to
warming is higher than that in the forested intercepted snow and
sheltered forest gap HRUs; this is due to suppression of blowing snow
redistribution processes by warming. In Wolf Creek (\(\approx 61\)° N),
not only more warming but also an increase in precipitation is expected
(Graversen et al., 2008), which indicates that precipitation increases
could partly offset the effect of warming on cold regions hydrology.
Despite the uniformity of high mountain climates and similar response
per degree increase in temperature, the implication of these results is
that mountain snow regime responses to climate change will differ
substantially (López-Moreno et al., 2020), as noted for the three basins
across North America studied here, therefore regional analysis is
required. The large difference between snowpack response in Reynolds
Mountain and Wolf Creek implies that warming in cool climates impacts
the maximum accumulated snowpack more than it does in cold climates.
Warming affects the phase of precipitation, causing a shift from
snowfall to rainfall in the spring and fall transition seasons (Poulin
et al., 2011; Whitfield and Shook, 2020) and a shift from March to
January in Reynolds Mountain, April to February in Marmot Creek and less
than a month in Wolf Creek for the timing of peak snow accumulation
(Table 2). The impacts of warming on snowpacks can be partly offset by a
precipitation increase in the cold Wolf Creek and Marmot Creek climates
but not in the cool Reynolds Mountain climate. The snow season is
expected to shorten by about two months in the subarctic Wolf Creek
(from 9 to 7 months), three and half months in the cold Marmot Creek
(from 6 to 4 months), and five months in the cool Reynolds Mountain
basin (from 6 to 1 month) with concomitant warming and a decline in
precipitation (Table 2). This implies that, if warming occurs, the
response of the snow hydrology to a precipitation increase changes with
latitude from very little in Reynolds Mountain to very large in Wolf
Creek. Snow hydrology is more sensitive to warming and precipitation
phase change in the southern basin and more resilient in Marmot Creek.