1.4 Trends in Arctic sea ice

Last Updated: 
June 2, 2015
This indicator reports on trends in observed Arctic sea ice, and observed changes to projected changes based on climate models.

This indicator is based on satellite data3, and provides analyses from Environment Canada's Sea Ice Service2,4,5, and the Fourth Assessment Report of the International Panel on Climate Change 2013 - The Physical Science Basis published by the World Meteorological Organization and the United Nations Environment Programme1.


Beaufort Sea
Beaufort Sea

NWT focus

Changes in global climate are predicted to be greater and more rapid in the Arctic than elsewhere. This indicator provides more detailed observations and predictions on ice in the Beaufort Sea. Sea ice is an important habitat component for Arctic wildlife and an important factor affecting local and global climate. Changes in the formation of Arctic ice are affecting the NWT environment in a complex way.

This indicator provides information for the entire Arctic Ocean and  for the Beaufort Sea that can be compared with more detailed information in the Focal Point CLIMATE AND WEATHER. The text is updated based on information from the Canadian Ice Service2 and the US National Snow and Ice Data Center3.

Current view: status and trend

Trends in the Arctic Ocean

The largest reductions in sea ice occur on thick multi-year ice in summer. A sharpest decline in sea ice minimum (September) cover occurred in 2007, and then a new minimum record was set in 2012.

Average monthly Arctic Sea Ice Extent September 1979-2014
Sea ice index: Extent and Concentration Trends, September (minimum) 1979-2014: Sea ice extent departures from September means for the Northern Hemisphere. For September 1973 to September 2014. Graph from US National Snow and Ice Data Center. This graph and more is available at the Sea Ice Index. 

Thinning of sea ice is also measured as an increase in the proportion of first-year ice (thinner) compared to multi-year ice (thicker). This thinner ice is more mobile and its movement can be greatly influenced by storm activities and ocean currents. The vulnerability of thin ice to ocean currents was demonstrated by the dramatic and previously unobserved opening of a large flaw lead in the Beaufort Sea just off the western coast of Banks Island in December 2007 - January 20084.

Massive fracture of Beaufort Ice Pack west of Banks Island, NWT
In December 2007, a massive fracture of the Beaufort Ice pack was observed west of Banks Island. Source: Image from NOAA, courtesy of: Environment Canada, Canadian Ice Service, Education Corner, Beaufort Sea (archived). Image from NOAA.

Trends in the Beaufort Sea

Reductions in sea ice cover during the fall minimum are not occurring at the same rate everywhere6. Sea ice trend studies for the Canadian Arctic indicate that while some areas show significant negative trends, many areas do not yet display detectable trends5. The most rapid changes are occurring in the Arctic basin, north of Alaska, and in the Barents Sea, north Scandinavia. There is less decline in sea ice concentration in some areas, such as north of the Canadian Archipelago and in the Beaufort Sea west of Banks Island5,6. This mostly occurs because ice is being piled up by the normal clockwise motion of the entire Arctic ice pack called the Beaufort Gyre.

Reductions in ice cover and ice thickness are resulting in increased vulnerability of Arctic coastal communities to storm surges and coastal erosion6 (see Indicator 1.7, Sea Level Rises). Local knowledge studies indicate that changes in sea ice are resulting in increasing dangers during off-shore travels, especially in fall and spring7,8. Reduced sea ice, earlier break-up of sea ice and more fall storms have resulted in more shore erosion in the Inuvialuit Settlement Region9,10.

Trends in summer sea ice
Figure A: Trends in summer Total Accumulated Coverage for all ice types combined, 1966-2010. Trends are expressed a percent change per decade. Figure B: Trends in summer Total Accumulated Coverage for old ice only, 1966-2010. Trends are expressed as a percent change per decade.Source: Canadian Ice Service5.

September 2012 broke the 2008 record for minimum sea ice extents and concentrations in the Beaufort Sea2. On 24 September 2012, only 2.22% of the Beaufort Sea was ice covered. This is related to the large loss of thick, multi-year sea ice from the Arctic Ocean as a result of melting in summer 2012 and as a result of enhanced transport of sea ice from the Arctic Ocean into the North Atlantic via the Fram Strait.

There is a significant negative trend in summertime ice amounts of all ice types along the Alaskan Coast. This is primarily related to increasing sea surface temperatures in this area10.

Linking ice to biodiversity





Ice edges
and polynyas

Enhanced primary production due to light and nutrients.

They can support intense phytoplankton blooms (Wang et al. 2005)
which are important to invertebrates and Arctic Cod then to other
species, such as birds and mammals.

Any time   

landfast ice

Ice algae provide an early and abundant food source for planktonic
grazers, such as pelagic copepods and amphipods,at a time when
other food sources are not available (Hill and Cota 2005, Michel et
al. 1996). 

Late Fall

Heavy ice

Barrier to feed for birds and polar bears, barriers to breathing for

Any time

Source: Canadian Biodiversity: Ecosystem Status and Trends Report. Available at Biodiversity Canada.

Looking forward

Raw data and analyses are shared across the world, including with scientists in Canada. This information was used by the International Panel on Climate Change to make predictions about the future extent of sea ice in the Arctic based on climate models:

“Arctic sea ice is very likely to decrease in its extent and thickness. It is uncertain how the Arctic Ocean circulation will change.”

The effects of Arctic Ocean circulation on the rate of decline in Arctic sea ice have been extensively studied and are proving to have an important role in the extremely fast reduction of summer sea ice compared to what were expected based on climate change models:

“Examination of the long-term satellite record dating back to 1979 and earlier records dating back to the 1950s indicate that spring melt seasons have started earlier and continued for a longer period throughout the year… Even more disquieting, comparison of actual Arctic sea ice decline to projections from the (Fourth Assessment Report of the International Panel on Climate Change -AR4) show that observed ice loss is faster than any of the …models have predicted …” .

Quote from the National Snow and Ice Data Center webpage3.

For more information

Other focal points

Contact us

Found an error or have a question? Contact the team at NWTSOER@gov.nt.ca.


Ref. 1. International Panel on Climate Change 2013 - AR5 - The Physical Science Basis.
Ref. 2. Environment Canada. 2014. Canadian Ice Service.
Ref. 3. NSIDC. 2014. Sea Ice Index. US National Snow and Ice Data Centre. 
Ref. 4. http://www.cbc.ca/m/touch/news/story/1.745570
Ref. 5. Tivy, A., S.E.L. Howell, B. Alt, S. McCourt, R. Chagnon, G. Crocker, T. Carrieres, and J.J. Yackel. 2011. Trends and variability in summer sea ice cover in the Canadian Arctic based on the Canadian Ice Service Digital Archive, 1960-2008 and 1968-2008. J. of Geophysical Research 116: C03007. 25pp.
Ref. 6. Barber, D.G., J.V. Lukovich, J. Keogak, S. Baryluk, L. Fortier, and G.H.R.  Henry. 2008. The changing climate of the Arctic. Arctic 61(1):7-26.
Ref. 7. Communities of Aklavik, Inuvik, Holman Island, Paulatuk and Tuktoyaktuk. Nickels S. Buell M. Furgal C. Moguin H., 2005, Unikkaaqatigiit - Putting the Human Face on Climate Change: Perspectives from the Inuvialuit Settlement Region. Ottawa: Joint publication on Inuit Tapiriit Kanatami, Nasivvik Centre for Inuit Health and Changing Environments at Universite Laval and the Ajunnginiq Centre at the National Aboriginal Health Organization.
Ref. 8. Pearce, T.D., B. Smit, F. Duerden, J. Ford, A. Goose, R. Inuktalik, and F. Kataoyak. 2006. Community adaptation and  vulnerability to climate change in Ulukhaktok. Conference and  Youth Forum 11-18 August 2006. Tuktoyaktuk, NWT.
Ref. 9. Manson G.K. and S.M. Solomon. 2007. Past and future forcing of Beaufort Sea coastal change. Atmosphere-Ocean 45:107-122.
Ref. 10. Trudy Wohlleben. 2008. Sea Ice Thickness/Distribution Trends. Canadian Wildlife Directors Committee Meeting. Ottawa, ON. October 29-31, 2008.