Sea ice in Canada
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Sea ice
National sea ice
Key results
- In 2018, the Northern Canadian Waters were covered by an average sea ice area of 1.23 million square kilometres, which represents 32.8% of its area
- Over the past 5 decades, the area covered by sea ice in the Northern Canadian Waters, measured during the summer season, has been decreasing
- Between 1968 and 2018, sea ice area in the Northern Canadian Waters declined at a rate of 7.0% per decade
Average sea ice area, Northern Canadian Waters, 1968 to 2018

Data table for the long description
Year |
Northern Canadian Waters sea ice area (millions of square kilometres) |
---|---|
1968 | 1.26 |
1969 | 1.53 |
1970 | 1.47 |
1971 | 1.32 |
1972 | 1.69 |
1973 | 1.30 |
1974 | 1.48 |
1975 | 1.34 |
1976 | 1.49 |
1977 | 1.28 |
1978 | 1.69 |
1979 | 1.44 |
1980 | 1.42 |
1981 | 1.19 |
1982 | 1.35 |
1983 | 1.62 |
1984 | 1.47 |
1985 | 1.36 |
1986 | 1.55 |
1987 | 1.40 |
1988 | 1.28 |
1989 | 1.42 |
1990 | 1.45 |
1991 | 1.44 |
1992 | 1.65 |
1993 | 1.31 |
1994 | 1.36 |
1995 | 1.20 |
1996 | 1.52 |
1997 | 1.27 |
1998 | 0.87 |
1999 | 1.11 |
2000 | 1.24 |
2001 | 1.23 |
2002 | 1.28 |
2003 | 1.20 |
2004 | 1.29 |
2005 | 1.17 |
2006 | 1.00 |
2007 | 0.94 |
2008 | 0.91 |
2009 | 1.15 |
2010 | 0.84 |
2011 | 0.74 |
2012 | 0.71 |
2013 | 1.13 |
2014 | 1.04 |
2015 | 1.12 |
2016 | 0.79 |
2017 | 0.94 |
2018 | 1.23 |
Download data file (Excel/CSV; 1.24 kB)
How this indicator was calculated
Note: Sea ice is measured during the summer season. For the Northern Canadian Waters, the summer season is defined as the period from June 19 to November 19 for the Hudson Bay domain and from June 25 to October 15 for the Canadian Arctic domain. A statistically significant trend is reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2018) Climate Research Division.
More information
Sea ice area decline in Northern Canadian Waters is the result of a combination of factors. Human-induced warming from greenhouse gas emissions and climate variability has resulted in an unprecedented loss of sea ice within the last 50 years in comparison to the last 1450 years.
The Arctic region is very sensitive to climate change because of feedback involving sea ice that influences the reflectivity of the Earth's surface. As sea ice area declines due to warming temperatures, darker ocean surfaces are exposed that can absorb more sunlight and in turn cause more warming and sea ice melting. This feedback cycle is an important factor in amplifying Arctic temperatures. Research has shown that the loss of Arctic sea ice is a very significant contributor to the recent amplification of Arctic temperature change compared to the global average.
Changes in the amount of sea ice, the location of ice edges and the timing of seasonal cycles have complex, cascading ecosystem impacts. Sea ice declines result in a loss of wildlife habitat, as it serves as hunting platforms for polar bears and as resting grounds and nursery areas for walruses and seals. Algae that grow on the underside of sea ice are also important to the marine food supply.
These changes also have an impact on safety of northerners who use sea ice as a transportation route or platform for hunting/fishing. More than ever, decisions on whether to go out on the ice must be made on the basis of weather and sea ice condition reports, as northerners can no longer rely on traditional knowledge of when it is safe to venture out on the ice.
Regional sea ice
In the Northern Canadian Waters, the area covered by sea ice, measured during the summer season, varies by sub-region. Five (5) sub-regions make up the Canadian Arctic domain (Kane Basin, Foxe Basin, Baffin Bay, the Beaufort Sea and the Canadian Arctic Archipelago) and 4 sub-regions comprise the Hudson Bay domain (Hudson Bay, Hudson Strait, Davis Strait and the Northern Labrador Sea).
Key results
- The Canadian Arctic Archipelago, Beaufort Sea and Kane Basin sub-regions usually remain covered by ice in the summer because they contain a mix of multi-year and seasonal ice
- The 4 sub-regions of the Hudson Bay domain (Hudson Bay, Hudson Strait, Davis Strait and Northern Labrador Sea) are typically sea ice free because they are seasonal ice regions
- All sub-regions have statistically significant decreasing trends over the 1968 to 2018 period, ranging from a 2.9% per decade in the Kane Basin to a 15.6% per decade in the Northern Labrador Sea
Sub-region sea ice area trends, Northern Canadian Waters, 1968 to 2018

Data table for the long description
Year |
Foxe Basin sea ice area (thousands of square kilometres) |
Kane Basin sea ice area (thousands of square kilometres) |
Baffin Bay sea ice area (thousands of square kilometres) |
Beaufort Sea sea ice area (thousands of square kilometres) |
Canadian Arctic Archipelago sea ice area (thousands of square kilometres) |
Hudson Bay sea ice area (thousands of square kilometres) |
Hudson Strait sea ice area (thousands of square kilometres) |
Davis Strait sea ice area (thousands of square kilometres) |
North Labrador Sea sea ice area (thousands of square kilometres) |
---|---|---|---|---|---|---|---|---|---|
1968 | 83 | 31 | 143 | 311 | 542 | 94 | 21 | 25 | 5 |
1969 | 59 | 32 | 172 | 431 | 544 | 191 | 25 | 34 | 5 |
1970 | 74 | 34 | 216 | 390 | 556 | 130 | 19 | 38 | 12 |
1971 | 66 | 33 | 177 | 354 | 482 | 109 | 30 | 31 | 9 |
1972 | 117 | 33 | 171 | 335 | 659 | 223 | 50 | 77 | 15 |
1973 | 64 | 34 | 157 | 375 | 476 | 125 | 30 | 49 | 3 |
1974 | 68 | 34 | 85 | 478 | 587 | 154 | 27 | 23 | 7 |
1975 | 53 | 34 | 87 | 457 | 520 | 109 | 17 | 27 | 8 |
1976 | 82 | 34 | 147 | 427 | 597 | 113 | 19 | 41 | 7 |
1977 | 73 | 35 | 210 | 286 | 515 | 84 | 15 | 41 | 6 |
1978 | 108 | 31 | 210 | 412 | 649 | 194 | 30 | 35 | 7 |
1979 | 76 | 33 | 139 | 327 | 662 | 127 | 22 | 37 | 6 |
1980 | 62 | 33 | 149 | 417 | 581 | 110 | 17 | 28 | 3 |
1981 | 44 | 31 | 127 | 353 | 471 | 104 | 14 | 28 | 2 |
1982 | 63 | 32 | 158 | 299 | 558 | 142 | 24 | 58 | 6 |
1983 | 90 | 35 | 187 | 453 | 539 | 162 | 38 | 81 | 12 |
1984 | 65 | 31 | 124 | 442 | 538 | 154 | 41 | 52 | 12 |
1985 | 56 | 30 | 85 | 459 | 513 | 133 | 27 | 24 | 10 |
1986 | 72 | 33 | 179 | 397 | 622 | 165 | 21 | 42 | 3 |
1987 | 86 | 30 | 188 | 275 | 587 | 158 | 26 | 32 | 7 |
1988 | 66 | 28 | 121 | 379 | 492 | 112 | 23 | 26 | 5 |
1989 | 81 | 35 | 177 | 388 | 537 | 141 | 20 | 28 | 5 |
1990 | 86 | 26 | 153 | 377 | 592 | 128 | 31 | 38 | 7 |
1991 | 69 | 33 | 108 | 467 | 553 | 122 | 27 | 34 | 12 |
1992 | 79 | 38 | 151 | 450 | 612 | 210 | 32 | 55 | 7 |
1993 | 68 | 31 | 212 | 253 | 526 | 142 | 21 | 42 | 4 |
1994 | 56 | 29 | 140 | 437 | 511 | 116 | 19 | 31 | 6 |
1995 | 56 | 25 | 169 | 284 | 531 | 94 | 12 | 14 | 0 |
1996 | 61 | 35 | 258 | 454 | 538 | 121 | 22 | 29 | 6 |
1997 | 49 | 35 | 156 | 312 | 576 | 102 | 16 | 17 | 3 |
1998 | 58 | 32 | 140 | 155 | 392 | 55 | 10 | 13 | 1 |
1999 | 59 | 31 | 144 | 335 | 458 | 37 | 8 | 27 | 5 |
2000 | 47 | 32 | 94 | 406 | 506 | 107 | 8 | 24 | 2 |
2001 | 57 | 34 | 102 | 425 | 522 | 51 | 6 | 18 | 1 |
2002 | 59 | 34 | 79 | 358 | 564 | 126 | 15 | 28 | 9 |
2003 | 52 | 30 | 74 | 352 | 556 | 103 | 9 | 18 | 2 |
2004 | 61 | 32 | 101 | 314 | 598 | 147 | 11 | 16 | 0 |
2005 | 40 | 30 | 112 | 354 | 549 | 64 | 10 | 10 | 1 |
2006 | 28 | 29 | 64 | 360 | 436 | 46 | 4 | 12 | 1 |
2007 | 54 | 25 | 96 | 242 | 408 | 76 | 10 | 18 | 5 |
2008 | 59 | 26 | 92 | 158 | 435 | 94 | 14 | 24 | 0 |
2009 | 52 | 22 | 69 | 306 | 505 | 139 | 17 | 28 | 6 |
2010 | 39 | 29 | 79 | 233 | 408 | 33 | 3 | 9 | 0 |
2011 | 45 | 25 | 73 | 190 | 340 | 59 | 3 | 6 | 0 |
2012 | 52 | 29 | 43 | 126 | 353 | 74 | 6 | 18 | 0 |
2013 | 57 | 35 | 67 | 339 | 504 | 84 | 9 | 17 | 5 |
2014 | 61 | 25 | 52 | 260 | 520 | 86 | 12 | 13 | 5 |
2015 | 65 | 35 | 128 | 261 | 418 | 140 | 18 | 47 | 3 |
2016 | 42 | 27 | 57 | 149 | 399 | 79 | 12 | 22 | 2 |
2017 | 43 | 28 | 96 | 199 | 471 | 60 | 9 | 36 | 0 |
2018 | 59 | 32 | 98 | 333 | 532 | 123 | 17 | 33 | 4 |
1968 to 2018 decadal trend | -7.4% | -2.9% | -12.2% | -7.5% | -4.3% | -9.5% | -14.0% | -11.4% | -15.6% |
Download data file (Excel/CSV; 3.06 kB)
How this indicator was calculated
Note: Sea ice is measured during the summer season. For the Northern Canadian Waters, the summer season is defined as the period from June 19 to November 19 for the Hudson Bay domain and from June 25 to October 15 for the Canadian Arctic domain. A statistically significant trend is reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2018) Climate Research Division.
More information
In absolute terms, the largest sea ice area loss over the 1968 to 2018 period was found in the Beaufort Sea sub-region, where about 187 000 km2 of sea ice area was lost. The Canadian Arctic Archipelago, Baffin Bay and Hudson Bay sub-regions also lost a large amount of sea ice area over the same period, with a detected loss of about 134 000 km2, 102 000 km2 and 73 000 km2, respectively.
Based on projections from the latest state-of-the-art climate models, a nearly sea ice-free summer is considered a strong possibility for the Arctic Ocean by the middle of the century although sea ice may persist longer in the Canadian Arctic Archipelago region.
Multi-year sea ice
National multi-year sea ice
Multi-year sea ice corresponds to ice that has survived at least one summer's melt. Multi-year sea ice contains less salt and is usually thicker than first-year sea ice. Because it contains less salt, it is harder and more difficult for icebreakers to navigate and clear.
Key results
In the Canadian Arctic domain:
- multi-year sea ice area, measured during the summer season, declined by 7.4% per decade over the 1968 to 2018 period
- total sea ice area declined by 7.0% per decade over the same period
Average multi-year sea ice area, Canadian Arctic domain, 1968 to 2018

Data table for the long description
Year |
Canadian Arctic domain multi-year sea ice area (thousands of square kilometres) |
---|---|
1968 | 516 |
1969 | 661 |
1970 | 543 |
1971 | 530 |
1972 | 472 |
1973 | 566 |
1974 | 498 |
1975 | 648 |
1976 | 644 |
1977 | 508 |
1978 | 551 |
1979 | 628 |
1980 | 679 |
1981 | 492 |
1982 | 369 |
1983 | 584 |
1984 | 533 |
1985 | 502 |
1986 | 542 |
1987 | 562 |
1988 | 589 |
1989 | 545 |
1990 | 619 |
1991 | 676 |
1992 | 687 |
1993 | 606 |
1994 | 603 |
1995 | 501 |
1996 | 666 |
1997 | 621 |
1998 | 393 |
1999 | 335 |
2000 | 421 |
2001 | 578 |
2002 | 486 |
2003 | 516 |
2004 | 541 |
2005 | 557 |
2006 | 500 |
2007 | 370 |
2008 | 260 |
2009 | 351 |
2010 | 345 |
2011 | 250 |
2012 | 207 |
2013 | 295 |
2014 | 406 |
2015 | 391 |
2016 | 286 |
2017 | 312 |
2018 | 521 |
Download data file (Excel/CSV; 1.12 kB)
How this indicator was calculated
Note: Sea ice is measured during the summer season. For the Canadian Arctic domain, the summer season is defined as the period from June 25 to October 15. A statistically significant trend is reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2018) Climate Research Division.
Regional multi-year sea ice
Key results
- In the Canadian Arctic domain, decreasing trends in multi-year sea ice, measured during the summer season, were found for the Foxe Basin, Kane Basin, Beaufort Sea and Canadian Arctic Archipelago sub-regions
- The Baffin Bay sub-region showed no significant increasing or decreasing trends from 1968 to 2018
- The sub-regions of the Hudson Bay domain were found to be free of multi-year ice over the whole time period because they are seasonal ice regions
Multi-year sea ice area in Canadian Arctic sub-regions, 1968 to 2018

Data table for the long description
Year |
Foxe Basin multi-year sea ice area (thousands of square kilometres) |
Kane Basin multi-year sea ice area (thousands of square kilometres) |
Baffin Bay multi-year sea ice area (thousands of square kilometres) |
Beaufort Sea multi-year sea ice area (thousands of square kilometres) |
Canadian Arctic Archipelago multi-year sea ice area (thousands of square kilometres) |
---|---|---|---|---|---|
1968 | 1.58 | 17 | 8 | 216 | 244 |
1969 | 0.14 | 23 | 28 | 319 | 289 |
1970 | 0.32 | 14 | 23 | 234 | 243 |
1971 | 0.83 | 16 | 16 | 256 | 201 |
1972 | 3.77 | 14 | 11 | 181 | 243 |
1973 | 0.88 | 19 | 15 | 202 | 301 |
1974 | 0.18 | 16 | 6 | 285 | 190 |
1975 | 0.45 | 16 | 5 | 374 | 235 |
1976 | 2.46 | 17 | 9 | 350 | 247 |
1977 | 0.16 | 14 | 15 | 181 | 293 |
1978 | 4.16 | 14 | 9 | 240 | 281 |
1979 | 5.88 | 15 | 10 | 213 | 383 |
1980 | 0.26 | 18 | 8 | 291 | 354 |
1981 | 0.35 | 16 | 18 | 213 | 237 |
1982 | 0.22 | 12 | 16 | 140 | 201 |
1983 | 3.91 | 21 | 44 | 252 | 255 |
1984 | 0.57 | 14 | 16 | 287 | 211 |
1985 | 0.43 | 13 | 2 | 271 | 207 |
1986 | 1.09 | 11 | 9 | 265 | 253 |
1987 | 0.77 | 13 | 8 | 190 | 346 |
1988 | 0.66 | 10 | 8 | 253 | 308 |
1989 | 0.24 | 17 | 10 | 245 | 273 |
1990 | 0.79 | 17 | 51 | 260 | 288 |
1991 | 1.74 | 6 | 7 | 340 | 313 |
1992 | 1.49 | 28 | 12 | 320 | 318 |
1993 | 1.37 | 24 | 60 | 190 | 328 |
1994 | 3.85 | 20 | 13 | 281 | 279 |
1995 | 0.65 | 17 | 43 | 203 | 233 |
1996 | 0.67 | 18 | 48 | 344 | 260 |
1997 | 0.21 | 22 | 22 | 255 | 320 |
1998 | 0.02 | 17 | 32 | 103 | 240 |
1999 | 0.40 | 13 | 13 | 205 | 102 |
2000 | 0.16 | 15 | 8 | 239 | 151 |
2001 | 0.03 | 17 | 12 | 308 | 232 |
2002 | <0.01 | 18 | 10 | 229 | 228 |
2003 | 0.11 | 14 | 8 | 232 | 263 |
2004 | 0.25 | 18 | 16 | 205 | 294 |
2005 | 0.39 | 14 | 7 | 240 | 295 |
2006 | 0.26 | 13 | 12 | 254 | 208 |
2007 | 0.00 | 13 | 27 | 163 | 168 |
2008 | 0.04 | 11 | 17 | 79 | 152 |
2009 | 0.06 | 9 | 10 | 164 | 168 |
2010 | 0.02 | 14 | 27 | 134 | 169 |
2011 | 0.00 | 12 | 9 | 111 | 119 |
2012 | 0.10 | 13 | 4 | 77 | 106 |
2013 | 0.16 | 12 | 5 | 146 | 131 |
2014 | 0.22 | 11 | 5 | 178 | 212 |
2015 | 0.13 | 15 | 12 | 191 | 172 |
2016 | <0.01 | 15 | 5 | 89 | 177 |
2017 | 0.06 | 16 | 16 | 60 | 220 |
2018 | 0.56 | 17 | 22 | 234 | 246 |
1968 to 2018 decadal trend | -18.5% | -3.4% | No trend | -8.8% | -6.5% |
Download data file (Excel/CSV; 2.19 kB)
How this indicator was calculated
Note: Sea ice is measured during the summer season. For the Canadian Arctic domain, the summer season is defined as the period from June 25 to October 15. A statistically significant trend is reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2018) Climate Research Division.
Sea ice in Canada's Northwest Passage
Sea ice area in Canada's Northwest Passage
Canada's Northwest Passage is a system of gulfs, straits, sounds and channels in the Canadian Arctic Archipelago connecting the Beaufort Sea in the west with Baffin Bay in the east. The Northwest Passage provides 2 main navigation paths on its western side: a northern route and a southern route.
Key results
- Over the 1968 to 2018 period, the amount of sea ice area covering the Northwest Passage, measured during the summer season, fluctuated in a similar way to the rest of the Canadian Arctic Waters
- Statistical decreasing trends were detected over this period for the sea ice and multi-year sea ice areas of the northern and southern routes
- The southern route was virtually free of multi-year sea ice for several of the recent years
Average sea ice and multi-year sea ice area, Canada's Northwest Passage, 1968 to 2018

Data table for the long description
Year |
Northwest Passage northern route sea ice area (thousands of square kilometres) |
Northwest Passage southern route sea ice area (thousands of square kilometres) |
Northwest Passage northern route multi-year sea ice area (thousands of square kilometres) |
Northwest Passage southern route multi-year sea ice area (thousands of square kilometres) |
---|---|---|---|---|
1968 | 127 | 81 | 64 | 8 |
1969 | 133 | 86 | 82 | 4 |
1970 | 130 | 98 | 55 | 7 |
1971 | 110 | 69 | 40 | 7 |
1972 | 146 | 147 | 61 | 13 |
1973 | 119 | 63 | 77 | 19 |
1974 | 132 | 134 | 36 | 7 |
1975 | 138 | 87 | 65 | 12 |
1976 | 138 | 123 | 73 | 14 |
1977 | 124 | 81 | 77 | 22 |
1978 | 159 | 142 | 62 | 31 |
1979 | 158 | 155 | 92 | 42 |
1980 | 139 | 115 | 77 | 36 |
1981 | 117 | 67 | 53 | 10 |
1982 | 131 | 110 | 40 | 9 |
1983 | 128 | 110 | 50 | 17 |
1984 | 138 | 94 | 48 | 6 |
1985 | 123 | 102 | 55 | 13 |
1986 | 141 | 137 | 67 | 26 |
1987 | 145 | 119 | 96 | 30 |
1988 | 126 | 62 | 84 | 14 |
1989 | 127 | 102 | 69 | 16 |
1990 | 143 | 114 | 76 | 26 |
1991 | 134 | 112 | 80 | 33 |
1992 | 145 | 120 | 84 | 21 |
1993 | 129 | 89 | 84 | 22 |
1994 | 129 | 88 | 87 | 19 |
1995 | 132 | 85 | 69 | 13 |
1996 | 134 | 90 | 69 | 23 |
1997 | 147 | 104 | 93 | 22 |
1998 | 94 | 55 | 60 | 19 |
1999 | 107 | 70 | 12 | 4 |
2000 | 119 | 93 | 26 | 3 |
2001 | 137 | 83 | 64 | 7 |
2002 | 140 | 111 | 53 | 10 |
2003 | 136 | 98 | 77 | 14 |
2004 | 140 | 122 | 91 | 19 |
2005 | 136 | 108 | 86 | 23 |
2006 | 116 | 53 | 66 | 7 |
2007 | 98 | 58 | 44 | 4 |
2008 | 104 | 62 | 32 | 5 |
2009 | 119 | 87 | 30 | 5 |
2010 | 81 | 55 | 21 | 6 |
2011 | 69 | 50 | 15 | 1 |
2012 | 74 | 56 | 20 | 1 |
2013 | 123 | 79 | 23 | 2 |
2014 | 126 | 84 | 32 | 8 |
2015 | 91 | 29 | 27 | 7 |
2016 | 106 | 43 | 49 | 6 |
2017 | 118 | 44 | 60 | 13 |
2018 | 137 | 54 | 60 | 21 |
1968 to 2018 decadal trend | -3.1% | -9.6% | -6.7% | -10.0% |
Download data file (Excel/CSV; 1.90 kB)
How this indicator was calculated
Note: Sea ice is measured during the summer season. For the Canadian Arctic domain, the summer season is defined as the period from June 25 to October 15. A statistically significant trend is reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2018) Climate Research Division.
Over the 1968 to 2018 period, statistical decreasing trends of 3.1% and 9.6% were detected for the sea ice areas of the northern and southern routes of the Northwest Passage. For multi-year sea ice, a decreasing trend of 6.7% per decade was detected for the northern route, while a decreasing trend of 10.0% was detected for the southern route.
Canada's Northwest Passage
Canada's Northwest Passage presents a potential deep-water Arctic shipping route between the northern Pacific and Atlantic regions that is much shorter than routes through the Panama or Suez canals. The Northwest Passage is covered by floating or land-fast sea ice Footnote 3 for most of the year, making it a navigation obstacle for ice-breaking ships and a safety hazard for non-ice strengthened ships.
Canada's Northwest Passage

Reduced sea ice is increasing opportunities for shipping, tourism, resource exploration and industrial activities in the North.
However, these activities bring new risks of accidents and spills under harsher conditions, including floating ice, changing sea ice cover and extreme weather. These factors can put people and ecosystems at risk and place additional stress on limited search and rescue, and disaster response capacity.
About the indicators
About the indicators
What the indicators measure
The Sea ice in Canada indicators provide information on the area of sea in Canada covered by ice during the summer season. Sea ice area represents the portion of marine area covered by ice. The area is evaluated using the Canadian Ice Service Digital Archive and is expressed in thousands or millions of square kilometres. The Sea ice in Canada indicators are provided for the Northern Canadian Waters, by sub-region and for the Northwest Passage. The indicators also present trends in total sea ice area and multi-year sea ice area. Multi-year sea ice is defined as sea ice that has survived at least one summer's melt.
Why these indicators are important
Sea ice is an indicator of how the climate is changing. It is a critical component of our planet because it influences the Arctic and global climate, ecosystems, and people who live in polar regions. Sea ice influences the climate through the sea ice–albedo feedback effect (or reflectivity of the Earth's surface). Changes in sea ice can also affect ocean currents and the exchange of heat and water vapour from ocean to atmosphere.
Sea ice affects marine transportation, commercial fishing, offshore resource development, the hunting and fishing patterns of Indigenous people, and tourism and recreation. Understanding how Canada's climate is changing is important for developing adaptive responses. The Sea ice in Canada indicators provide a way to communicate to Canadians how Canada's Arctic sea ice has changed.
The Intergovernmental Panel on Climate Change and the World Meteorological Organization use sea ice, among several other variables, to assess long-term changes in climate. Sea ice is considered by the World Meteorological Organization's Global Climate Observing System to be an Essential Climate Variable.
Related indicators
The Temperature change in Canada indicator measures yearly and seasonal surface air temperature departures in Canada, while the Precipitation change in Canada indicator measures annual and seasonal precipitation departures.
The Snow cover indicators provide information on spring snow cover extent and annual snow cover duration in Canada.
Data sources and methods
Data sources and methods
Data sources
Sea ice data used in these indicators were provided by Environment and Climate Change Canada's Climate Research Division. The sea ice area data were computed from the weekly sea ice charts (Canadian Ice Service Digital Archive) produced by Environment and Climate Change Canada's Canadian Ice Service.
More information
Spatial coverage
The indicators provide coverage for the Northern Canadian Waters which are comprised of the Canadian Arctic domain and the Hudson Bay domain. Five sub-regions make up the Canadian Arctic domain (Kane Basin, Foxe Basin, Baffin Bay, the Beaufort Sea and the Canadian Arctic Archipelago) and four sub-regions comprise the Hudson Bay domain (Hudson Bay, Hudson Strait, Davis Strait and the Northern Labrador Sea).
Sea ice sub-regions of the Northern Canadian Waters

Source: Environment and Climate Change Canada (2018) Canadian Ice Service.
Temporal coverage
The indicators are calculated using data for the summer sea ice season for the years 1968 to 2018. The summer sea ice season is defined as the period from June 25 to October 15 for the Canadian Arctic domain and from June 19 to November 19 for the Hudson Bay domain. These intervals correspond to the summer shipping season of each domain, a period during which the Canadian Ice Service produces weekly regional sea ice charts.
Data completeness
The data for these indicators are compiled by the Canadian Ice Service and grouped into time series by the Climate Research Division to ensure comparability. The data incorporate information from many different sources such as satellite data, surface observations, airborne and ship reports, and model results, along with the expertise of experienced ice forecasters. The Canadian Ice Service sea ice data provide the authoritative Canadian record for sea ice in Canada.
Data timeliness
The data used in the Sea Ice in Canada indicators are current up to 2018.
Methods
The Sea ice in Canada indicators are based on the sea ice area data provided by Environment and Climate Change Canada's Climate Research Division.
For each region and sub-region, an average sea ice area is calculated from the summer season weekly sea ice charts for each year, from 1968 to 2018.
A statistical analysis is carried out using the Mann-Kendall and SEN's methods (Kendall-tau) to identify the presence of statistical linear trends at the 95% confidence level.
More information
The Sea Ice in Canada indicators use the weekly sea ice charts produced by the Canadian Ice Service. Weekly sea ice charts are primarily produced using imagery from RADARSAT-1 (since 1996) and RADARSAT-2 (since 2008) satellites. Other remote sensing data sources are also used, such as the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer and Moderate-Resolution Imagine Spectrometer imagery. Where possible, the interpretation of satellite data is verified using observations from the Canadian Ice Service specialists onboard dedicated aircraft and Canadian Coast Guard ships.Footnote 4
The Canadian Ice Service ice charts indicate the ice concentration in tenths and its stage of development. They also list the mean and normal 1981–2010 temperatures of some of the region's stations, which give an indication of one of the factors contributing to current ice conditions. Ice information is presented using the World Meteorological Organization's terminology. For more information about how the Canadian Ice Service produces weekly sea ice charts and maps, consult the Regional Ice Charts or the Manual of Standard Procedures for Observing and Reporting Ice Conditions.
The weekly sea ice charts are compiled into time series by the Climate Research Division for each region and sub-region. The sea ice area for a given year corresponds to the average area calculated from the weekly sea ice charts of the summer season.
The summer season was chosen because it represents the time when the amount of sea ice reaches its minimum, which is widely utilized within the scientific community as a measure of climate variability. It is also the time period when the most visible changes in sea ice occur. Historically, sea ice charts have been generated to support the shipping season, which is highest during the summer.
Non-parametric statistical tests were carried out on temporal sea ice area data to detect the presence of a linear trend and, if present, to determine the orientation (positive or negative) and magnitude of the rate of change (slope). The standard Mann-Kendall trend test was used to detect trend presence and orientation, while the Sen's pairwise slope method was used to estimate the slope. A trend was reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level.
Caveats and limitations
Care should be taken when using these indicators as proxies of the actual sea ice area change in specific locations. Sea ice area change could vary considerably within a sub-region, the smallest unit of analysis in these indicators.
Resources
Resources
References
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Related information
Haas C and Howell S (2015) Ice thickness in the Northwest Passage. Geophysical Research Letters 42(18):7673-7680.Retrieved on December 10, 2018.
Howell S, Derksen C, Pizzolato L and Brady M (2015) Multiyear ice replenishment in the Canadian Arctic Archipelago: 1997-2013. Journal of Geophysical Research: Oceans 120(3):1623-1637.Retrieved on December 10, 2018.
Intergovernmental Panel on Climate Change (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Chapter 4 Observations: Cryosphere (PDF; 12.5 MB). Retrieved on December 10, 2018.
National Snow & Ice Data Center (2018) All About Sea Ice. Retrieved on December 10, 2018.
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