Canadian snow and sea ice: historical trends and projections

Abstract

Abstract. The Canadian Sea Ice and Snow Evolution (CanSISE) Network is a climate research network focused on developing and applying state of the art observational data to advance dynamical prediction, projections, and understanding of seasonal snow cover and sea ice in Canada and the circumpolar Arctic. Here, we present an assessment from the CanSISE Network on trends in the historical record of snow cover (fraction, water equivalent) and sea ice (area, concentration, type, and thickness) across Canada. We also assess projected changes in snow cover and sea ice likely to occur by mid-century, as simulated by the Coupled Model Intercomparison Project Phase 5 (CMIP5) suite of Earth system models. The historical datasets show that the fraction of Canadian land and marine areas covered by snow and ice is decreasing over time, with seasonal and regional variability in the trends consistent with regional differences in surface temperature trends. In particular, summer sea ice cover has decreased significantly across nearly all Canadian marine regions, and the rate of multi-year ice loss in the Beaufort Sea and Canadian Arctic Archipelago has nearly doubled over the last 8 years. The multi-model consensus over the 2020–2050 period shows reductions in fall and spring snow cover fraction and sea ice concentration of 5–10 % per decade (or 15–30 % in total), with similar reductions in winter sea ice concentration in both Hudson Bay and eastern Canadian waters. Peak pre-melt terrestrial snow water equivalent reductions of up to 10 % per decade (30 % in total) are projected across southern Canada.

Natural Variability Has Slowed the Decline in Western U.S. Snowpack Since the 1980s

“…During this 35-year period, only four sites experienced a statistically significant decline in 1-April snowpack (95% confidence), while 208 sites (63%) experienced an insignificant decline. This result is consistent with Mudryk et al (2018), who found similar stability in the spring snowpack of western Canada over roughly the same time period. We find a similar result when we repeat the analysis using regionally averaged time series of 1-April snowpack (Figure 1b), with no region exhibiting a statistically significant trend since 1983-1984.…”

“…We find a similar result when we repeat the analysis using regionally averaged time series of 1-April snowpack (Figure 1b), with no region exhibiting a statistically significant trend since 1983-1984. This result is consistent with Mudryk et al (2018), who found similar stability in the spring snowpack of western Canada over roughly the same time period. Meanwhile, the average winter surface temperature over the western U.S. increased by more than 1 ∘ C during this period-on par with the average warming trend across global land surfaces ( Figure S2).…”

Satellite and In Situ Observations for Advancing Global Earth Surface Modelling: A Review

“…The latest IPCC (Intergovernmental Panel on Climate Change) assessment [18] indicates that further warming, even for only 0.5 • C of global warming, would further increase the occurrence or intensity of warm spells on global scale, of heavy precipitation in several regions, and of droughts in some regions; heavy precipitation associated with tropical cyclones is also projected to increase with increased global warming. Similarly, the fast-paced change observed for the cryosphere including the significant trends in both snow and sea-ice cover [20][21][22] means that we need an improved account of surface thermodynamic processes at the relevant scales in interaction with the diurnal cycle and synoptic variability. Observing and simulating the response of land biophysical variables and the cryosphere to extreme events is a major scientific challenge in Numerical Weather Prediction (NWP) and environmental applications, which is relevant also in the context of climate change adaptation.…”

The Ocean CO2 Sink in the Canadian Arctic Archipelago: A Present‐Day Budget and Past Trends Due to Climate Change

“…Figure also shows significant interannual variability over the 6‐year study period. For example, 2010 and 2011 are notable for strong CO 2 uptake across most of the central archipelago, associated with extremely light ice conditions in those years (Mudryk et al, ). In contrast, 2014 showed weak uptake in many regions, particularly Victoria Strait.…”

“…This variability in calculated fluxes across the CAA is a result of well-documented variability in sea ice conditions that lead to variations in open water length. Variable sea ice conditions have been linked to variability in both thermodynamic factors (e.g., air temperature and radiation balance) and the dynamic transport of multiyear ice through McClure Strait, the Queen Elizabeth Islands, and Victoria Strait (e.g., Howell et al, 2015;Mudryk et al, 2018).…”