|Title||Changes in snow, ice, and permafrost across Canada|
|Author||Derksen, C; Burgess, D; Duguay, C; Howell, S; Murdyk, L; Smith, S; Thackeray, C; Kirchmeier-Young, M|
|Source||Canada's changing climate report; by Bush, E (ed.); Lemmen, D S (ed.); 2019 p. 194-259|
|Links||Online - En ligne|
|Alt Series||Natural Resources Canada, Contribution Series 20180075|
|Publisher||Government of Canada|
|Media||paper; on-line; digital|
|Related||This publication is contained in Bush, E; Lemmen, D S;
(2019). Canada's changing climate report|
|Related||This publication is a translation of Derksen, C; Derksen, C;
Burgess, D; Burgess, D; Duguay, C; Duguay, C; Howell, S; Howell, S; Murdyk, L; Murdyk, L; Smith, S; Smith, S; Thackeray, C; Thackeray, C; Kirchmeier-Young, M; Kirchmeier-Young, M; (2019). Évolution de la neige, de la glace et du pergélisol à
l'échelle du Canada, Rapport sur le climat changeant du Canada|
|File format||pdf (Adobe® Reader®)|
|Province||British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut; Northern offshore
region; Eastern offshore region; Western offshore region|
|NTS||1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65;
66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560|
|Lat/Long WENS||-141.0000 -50.0000 90.0000 41.7500|
|Subjects||Nature and Environment; surficial geology/geomorphology; environmental geology; hydrogeology; climate; climatology; climate effects; snow; ice; permafrost; ground ice; sea ice; glaciers; surface waters;
rivers; lakes; temperature; precipitation; ground temperatures; oceanography; climate, arctic; Canadian Cordillera; climate change; ice caps; fresh water|
|Illustrations||geoscientific sketch maps; time series; bar graphs; graphs; location maps; histograms; tables|
|Released||2019 04 02|
Over the past three decades, the proportion of Canadian land and marine areas covered by snow and ice have decreased, and permafrost temperatures have risen (see Figure 5.1). These
changes to the Canadian cryosphere are consistent with those observed in other northern regions (Alaska, northern Europe, and Russia).
Snow cover fraction (SCF) decreased across most of Canada during the 1981-2015 period due to delayed snow cover
onset in fall and earlier snow melt in spring. Regional and seasonal variability in the SCF trends reflects internal climate variability in surface temperature trends. Over the same time period, seasonal maximum snow water equivalent (SWEmax), which
is indicative of seasonally accumulated snow available for spring melt, decreased across the Maritimes, southern Ontario, and nearly all of Canadian land areas north of 55º north latitude, while it increased across southern Saskatchewan and parts of
Alberta and British Columbia.
Significant reductions in sea ice area over the period 1968-2016 were evident in the summer and fall across the Canadian Arctic (5% to 20% per decade, depending on region), and in winter and spring in eastern Canadian
waters (5% to 10% per decade). Perennial sea ice in the Canadian Arctic is being replaced by thinner seasonal sea ice: multi-year ice losses are greatest in the Beaufort Sea and the Canadian Arctic Archipelago (CAA), approaching 10% per decade.
Sixty-year records of landfast sea ice thickness show evidence of thinning ice in the CAA.
Glaciers in Canada have receded over the past century, with a rapid acceleration in area and mass losses over the past decade, due primarily to increasing
air temperature. Recent mass loss rates are unprecedented over several millennia. Lake ice cover is changing across Canada, driven primarily by earlier spring breakup. Seasonal ice cover duration declined for approximately 80% of Arctic lakes between
2002 and 2015. Permafrost in the central and southern Mackenzie Valley has warmed at a rate of approximately 0.2ºC per decade since the mid-1980s. While modest, these increases are important because permafrost temperatures in these regions are
currently close to zero, so the ground is vulnerable to thawing. Permafrost temperatures in the high Arctic have increased at higher rates than in the sub-Arctic, ranging between 0.7ºC and 1ºC per decade.
These changes to the cryosphere during
recent decades are in large part a response to increasing surface temperatures. Regional and seasonal variability are due to natural climate variability in surface temperature trends, changes in the amount and the phase (rain or snow) of
precipitation, and to remote influences within the global climate system (such as variations in ocean circulation and sea surface temperatures). Changes to individual components of the cryosphere are interconnected. For example, snow is an effective
insulator, so changes in the timing of snow cover onset and the seasonal accumulation of snow strongly influence underlying ground temperature and the thickness of lake and sea ice.
Further changes to the cryosphere over the coming decades are
virtually certain, as temperatures are projected to increase under all future emission scenarios. There is robust evidence that snow cover extent and accumulation, sea ice extent and overall thickness, and the mass of land ice will continue to
decrease across Canada throughout the 21st century. Most Canadian Arctic marine regions could be sea ice-free for at least one month in the summer by 2050, but sea ice will continue to be found along the northern coast of the CAA. Reductions in
glacier mass in western Canada will impact the magnitude and seasonality of streamflow, affecting the availability of freshwater for human use. Warming will lead to a loss of permafrost and alteration of the landscape as thawing occurs. These changes
to the cryosphere will not be spatially uniform due to regional effects of natural climate variability at decadal to multi-decadal time scales.
|Summary||(Plain Language Summary, not published)|
As part of Canada in a Changing Climate, the Government of Canada undertook a report on observed climate trends and future climate changes. Led by
Environment and Climate Change Canada, this report will provides the climate science foundation for other National Assessment products. It will also inform adaptation decision-making and be a key awareness-building tool. The report presents
information on climate science and assess observed and future changes in key climate indicators for all of Canada. This chapter focusses on snow ice and permafrost.