Sea ice in Canada

National sea ice

Key results

• In 2022, the summer sea ice area in the Northern Canadian Waters reached a low of 1.05 million square kilometres (km²), representing 27.9% of the total area (3.76 million km²)
• Since 1968, the lowest summer sea ice area occurred in 2012 at 0.70 million km²
• Over the period 1968 to 2022, summer sea ice area in the Northern Canadian Waters declined at a rate of 7.1% per decade

Average summer sea ice area, Northern Canadian Waters, 1968 to 2022

How this indicator was calculated

Note: Sea ice area is measured during the summer season. 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 indicates the presence of a trend at the 95% confidence level.

Source: Environment and Climate Change Canada (2022) Climate Research Division.

Sea ice area decline in the 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 over the last 50 years.^{Footnote 2 Footnote 3} 

Arctic sea ice is very sensitive to climate change because of the sea ice-albedo feedback that influences how much solar radiation is absorbed into the sea ice-ocean system. As sea ice area declines due to warming temperatures, more dark ocean surfaces that readily absorb sunlight (solar radiation) are exposed, in turn causing more sea ice to melt. 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.^{Footnote 4} 

Changes in the amount of sea ice, the location of ice edges and the timing of seasonal ice formation and melt have complex, cascading ecosystem impacts.^{Footnote 5} 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 the safety of northerners who use sea ice as a transportation route or platform for hunting and fishing.

Regional sea ice

In the Northern Canadian Waters, the summer sea ice area 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). 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 first-year ice. The 4 sub-regions of the Hudson Bay domain are typically free of sea ice in summer. 

Key results                                                               

• All sub-regions exhibit statistically significant decreasing trends in summer sea ice area over the 1968 to 2022 period, ranging from a 3.2% decrease per decade in the Kane Basin to a 15.7% decrease per decade in the Northern Labrador Sea 

Sub-region summer sea ice area trends, Northern Canadian Waters, 1968 to 2022

How this indicator was calculated

Note: Sea ice area is measured during the summer season. 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 indicates the presence of a trend at the 95% confidence level. 

Source: Environment and Climate Change Canada (2022) Climate Research Division.

In absolute terms, the largest summer sea ice area loss over the 1968 to 2022 period has occurred in the Beaufort Sea sub-region, where approximately 190 000 km² of sea ice was lost (which corresponds to almost 4 times the land area of Nova Scotia). The Canadian Arctic Archipelago, Baffin Bay and Hudson Bay sub-regions also lost a large amount of sea ice area over the same period, of approximately 144 000 km², 109 000 km² and 69 000 km², respectively.

Each year, the minimum sea ice area is observed during the month of September. At this time of the year, all the sea ice in the Hudson Bay domain has melted. The Canadian Arctic domain’s sub-regions present statistically significant decreasing trends in average September sea ice area over the 1968 to 2022 period, except for the Kane Basin where no statistically significant trend was reported. In the Canadian Arctic, a decrease of 9.1% per decade has been observed for the September sea ice area, which is lower than the 12.3% decadal decrease observed for the entire Arctic sea ice extent.^{Footnote 6 Footnote 7}

Sub-region September sea ice area decadal trends, Canadian Arctic domain, 1968 to 2022

How this indicator was calculated

Note: The trends presented correspond to the decadal trend over the period from 1968 to 2022. The September sea ice area trend is calculated based on the average sea ice area during the month of September for each year from 1968 to 2022. A statistically significant trend is reported when the Mann-Kendall test indicates the presence of a trend at the 95% confidence level.

Source: Environment and Climate Change Canada (2022) Climate Research Division.

Climate projections suggest that a nearly sea ice-free summer is possible for the Arctic Ocean by the middle of the 21st century, although sea ice may persist longer in the Canadian Arctic Archipelago region.^{Footnote 8} 

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, making it harder and more difficult for icebreakers to navigate and clear. Considering that the sub-regions from the Hudson Bay domain are first-year ice regions that are free of multi-year ice during summer, the indicators focus on summer multi-year sea ice in the Canadian Arctic domain. 

Key results

In the Canadian Arctic domain:

• Over the period 1968 to 2022, multi-year ice in the summer season made up between a low of 26% to a high of 51% of the total summer sea ice area 
• The summer multi-year sea ice area has declined by 7.7% per decade over the period from 1968 to 2022
• In 2022, the average summer multi-year sea ice area reached 438 000 km²
• Since 1968, the lowest summer multi-year sea ice area occurred in 2012, with 207 000 km²

Average summer multi-year sea ice area, Canadian Arctic domain, 1968 to 2022

How this indicator was calculated

Note: Multi-year sea ice area is measured during the summer season. The summer season is defined as the period from June 25 to October 15 for the Canadian Arctic domain. A statistically significant trend is reported when the Mann-Kendall test indicates the presence of a trend at the 95% confidence level.

Source: Environment and Climate Change Canada (2022) Climate Research Division.

Regional multi-year sea ice

Key results

• In the Canadian Arctic domain, statistically significant decreasing trends in the average multi-year sea ice 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 trend from 1968 to 2022

Sub-region summer multi-year sea ice area trends, Canadian Arctic domain, 1968 to 2022

How this indicator was calculated

Note: Multi-year sea ice area is measured during the summer season. The summer season is defined as the period from June 25 to October 15 for the Canadian Arctic domain. A statistically significant trend is reported when the Mann-Kendall test indicates the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2022) Climate Research Division.

Each year, the minimum multi-year sea ice area is observed during the month of September. A decrease in the average September multi-year sea ice in the Canadian Arctic was observed over the 1968 to 2022 period, with a reduction of 9.0% per decade. All sub-regions of the Canadian Arctic domain exhibited statistically significant decreasing trends, except Kane Basin.

Sub-region September multi-year sea ice area decadal trends, Canadian Arctic domain, 1968 to 2022

How this indicator was calculated

Note: The trends presented correspond to the decadal trend over the period from 1968 to 2022. The September multi-year sea ice area trend is calculated based on average multi-year sea ice area during the month of September for each year from 1968 to 2022. A statistically significant trend is reported when the Mann-Kendall test indicates the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2022) Climate Research Division.

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 that connects the Atlantic and Pacific Oceans. There are 2 main navigation paths through the Northwest Passage: a northern route and a southern route.

Key results

• Over the 1968 to 2022 period, statistically significant decreasing trends were detected for both the total sea ice and multi-year sea ice areas in the summer season
  • Decreases of 3.3% and 7.4% per decade were detected for the summer sea ice areas of the northern and southern routes of the Northwest Passage, respectively. 
  • For summer multi-year sea ice, a decreasing trend of 6.1% per decade was detected for the northern route, while a decreasing trend of 11.4% per decade was detected for the southern route.
• Since 1968, the lowest sea ice area was observed in 2011 for the northern route (69 000 km²), and in 2016 for the southern route (50 000 km²)
• Since 1968, the lowest multi-year sea ice area occurred in 1999 for the northern route (12 000 km²), and in 2012 for the southern route (847 km²)

Average total and multi-year summer sea ice area, Canada’s Northwest Passage, 1968 to 2022

How this indicator was calculated

Note: Sea ice area 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 indicates the presence of a trend at the 95% confidence level.
Source: Environment and Climate Change Canada (2022) Climate Research Division.

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 sea ice 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

Source: Environment and Climate Change Canada (2018) Canadian Research Division.

Reduced sea ice is increasing opportunities for shipping, tourism, resource exploration and industrial activities in the North. However, these activities bring new risks of marine accidents from a changing sea ice cover that can put people and ecosystems at risk and place additional stress on limited search and rescue and disaster response capacity.

^{Footnote 9}

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 the 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 the ocean to the atmosphere.

Sea ice affects marine transportation, commercial fishing, offshore resource development, the hunting and fishing patterns of Indigenous peoples, 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 the coverage of 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 Initiatives

These indicators support the measurement of progress towards the following 2022 to 2026 Federal Sustainable Development Strategy Goal 13: Take action on climate change and its impacts.

In addition, the indicators contribute to the Sustainable Development Goals of the 2030 Agenda for Sustainable Development. They are linked to Goal 13, Take urgent action to combat climate change and its impacts.

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

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 (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).

Sea ice sub-regions of the Northern Canadian Waters

Source: Environment and Climate Change Canada (2018) Canadian Research Division.

Long description

The map of Canada shows 9 sub-regions that make up the Northern Canadian Waters. The sub-regions are Baffin Bay, Beaufort Sea, Canadian Arctic Archipelago, Davis Strait, Foxe Basin, Hudson Bay, Hudson Strait, Kane Basin, and the Northern Labrador Sea.

Temporal coverage

The indicators are calculated using data for the summer sea ice season for the years 1968 to 2022. 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 provides 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 2022.

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 2022.

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.

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

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 to 7680.

Howell SEL and Brady M (2019) The dynamic response of sea ice to warming in the Canadian Arctic Archipelago. Geophysical Research Letters, 46. 13119-13125.

National Snow & Ice Data Center (2022) All About Sea Ice.