Spatial and Temporal Shifts in Historic and Future Temperature and Precipitation Patterns Related to Snow Accumulation and Melt Regimes in Alberta, Canada

Brandi W Newton,Babak Farjad,John F Orwin

doi:10.3390/w13081013

Abstract

Shifts in winter temperature and precipitation patterns can profoundly affect snow accumulation and melt regimes. These shifts have varying impacts on local to large-scale hydro-ecological systems and freshwater distribution, especially in cold regions with high hydroclimatic heterogeneity. We evaluate winter climate changes in the six ecozones (Mountains, Foothills, Prairie, Parkland, Boreal, and Taiga) in Alberta, Canada, and identify regions of elevated susceptibility to change. Evaluation of historic trends and future changes in winter climate use high-resolution (~10 km) gridded data for 1950–2017 and projections for the 2050s (2041–2070) and 2080s (2071–2100) under medium (RCP 4.5) and high (RCP 8.5) emissions scenarios. Results indicate continued declines in winter duration and earlier onset of spring above-freezing temperatures from historic through future periods, with greater changes in Prairie and Mountain ecozones, and extremely short or nonexistent winter durations in future climatologies. Decreases in November–April precipitation and a shift from snow to rain dominate the historic period. Future scenarios suggest winter precipitation increases are expected to predominantly fall as rain. Additionally, shifts in precipitation distributions are likely to lead to historically-rare, high-precipitation extreme events becoming more common. This study increases our understanding of historic trends and projected future change effects on winter snowpack-related climate and can be used inform adaptive water resource management strategies.

Highlights

Winter climate dynamics including sustained below-freezing temperatures and snow accumulation are critical for the seasonal redistribution of freshwater in many hydrological systems in western Canada, especially those with mountainous, high elevation headwaters.The accumulation of snow in alpine headwaters acts as a large and transient natural reservoir, gradually supplying fresh water to downstream regions during the warm season as a function of elevation and aspect controls on both snow accumulation and melt [1].Multiple studies demonstrate that climate has changed over recent decades and is projected to continue to change, during winter months [2,3]
Widespread significant (p < 0.05) negative trends are detected across Alberta for the spring 0 ◦ C isotherm and winter duration over the historic period, signifying an earlier onset of above-freezing temperatures and shorter winter duration (Figure 2)
The historic period was dominated by trends toward an earlier onset of spring above-freezing temperatures, shorter winter duration, decreased precipitation coupled with a shift from snow to rain, especially in the Prairie and Parkland ecozones

Summary

Introduction

Winter climate dynamics including sustained below-freezing temperatures and snow accumulation are critical for the seasonal redistribution of freshwater in many hydrological systems in western Canada, especially those with mountainous, high elevation headwaters. Multiple studies demonstrate that climate has changed over recent decades and is projected to continue to change, during winter months [2,3]. These shifts will have profound impacts on the spatial and temporal distribution of freshwater sourced from snow melt [4,5]. Changes to cold season temperature and precipitation can have considerable impacts on hydro-ecological systems downstream of mountain headwater regions. Our understanding of how shifting winter temperature and precipitation patterns may affect snow accumulation and melt in different regions is limited

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Results

Discussion

Conclusion