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.