Recent Changes in the Sea Ice of the Canadian Arctic Archipelago
Tom A. Agnew1, Stephen Howell2, Adrienne Tivy3
1Climate Research Division, Environment Canada, Canadian Government, 4905 Dufferin Street, Toronto, ON, M3H5T4, Canada, Phone 416-739-4385, Fax 416-739-5700, tom [dot] agnew [at] ec [dot] gc [dot] ca
2Climate Research Division, Environment Canada, Canadian Government, 4905 Dufferin Street, Toronto, ON, M3H5T4, Canada, stephen [dot] howell [at] ec [dot] gc [dot] ca
3International Arctic Research Center, University of Alaska, Fairbanks, AK, USA, adrienne [dot] tivy [at] ec [dot] gc [dot] ca
The narrow channels and waters of the Canadian Arctic Archipelago (CAA) produce one of the most complex sea ice regimes in the Arctic. In addition, large scale sea ice dynamics suggests that this region could have a continual supply of pack ice from the Arctic Ocean and therefore be the last region to lose its seasonal sea ice cover. Research activities under the Canadian International Polar Year Project "Variability and Change in the Cryosphere" have focused on enhancing our understanding of this sea ice regime through the digitization and analysis of Canadian ice charts back to 1960. Presently, the CAA is a region of net sea ice production rather than a pathway for pack ice from the Arctic Ocean through the CAA to the northwest Atlantic like Nares Strait and Fram Strait. Consolidation of the ice cover and the formation of ice arches in winter restrict sea ice transport. However this may eventually change.
Recent studies find the annual total sea ice coverage in the CAA has decreased by -2.9 % per decade with September decreases at ~ -8.7 % per decade. These reductions in sea ice cover are explained by increases in early summer surface air temperature and an increase melt season length at 7 days per decade. Heavy multi-year ice (MYI) conditions within the CAA are attributed to persistence of MYI from either dynamic import and/or first year ice (FYI) which has survived the melt season and is promoted to MYI. The El Niño-Southern Oscillation index correlates with MYI coverage (positive correlation) and first-year ice coverage (negative correlation) suggesting that El Niño episodes precede summers with more MYI and less FYI. MYI coverage is also decreasing but has yet to reach statistical significance as a result of increasing MYI dynamic import from the Arctic Ocean. The latter is attributed to the source of MYI which is changing from in situ FYI aging to dynamic import of MYI from the Arctic Ocean attributed to a longer melt season. Between 1960 and 2008, no significant trends were found along the northern route of the Northwest Passage yet the clearing processes responsible for record low ice cover in 2007 were very similar to the record low ice in 1962.