Sea-Ice History of the Northwest Passage

Activity Rationale

Art Dyke recording a bowhead whale skull in a raised beach now 23 m above sea level on Somerset Island, central Canadian Arctic.
Art Dyke recording a bowhead whale skull in a raised beach now 23 m above sea level on Somerset Island, central Canadian Arctic. Larger image

The opening of the Northwest Passage has important implications for international shipping, resource development, sovereignty, and northern ecosystems. This activity assesses the sensitivity of the sea-ice cover in the Canadian Arctic to climate change and explores how changes in ice cover have affected the distributions of sea mammals and hunter-gatherer economies in the past.

Leader: Art Dyke


James M. Savelle (McGill University) examining a Paleoeskimo dwelling feature on a raised beach at 14 m elevation on western Boothia Peninsula, central Canadian Arctic.
James M. Savelle (McGill University) examining a Paleoeskimo dwelling feature on a raised beach at 14 m elevation on western Boothia Peninsula, central Canadian Arctic. Larger image

The Topic

Numerical climate models predict that the Northwest Passage and the Arctic Ocean may become ice-free in summer during this century. This activity explores whether the Passage was ice-free under previous climatic conditions and attempts to determine what the threshold condition for an opening in the Passage might be. Changing sea-ice conditions determine the seasonal geographical ranges of Arctic sea mammals, which have been an important part of northern hunter-gather economies over the past 5000 years. Therefore, this activity also aims to reconstruct relative human population levels over the past 5000 years along the Northwest Passage and infer what might have caused these levels to change.

A continuous record of marine coastal conditions may be found in the raised beach sequences of Arctic Canada. These beaches have become elevated because of postglacial rebound from removal of the glacial ice load. Raised beaches were searched for the remains of bowhead whales and for former dwelling of Paleoeskimos. When dated by radiocarbon dating methods, whale bones can reveal when summer open water (ice-free Northwest Passage) permitted access to regions not accessible historically. Paleoeskimos tended to camp very close to the shoreline. Therefore, the number and sizes of dwellings on raised beaches are a good indication of former population levels. Dwellings may also be datable by radiocarbon methods using food bones or hearth charcoal.

Raised beaches in the Canadian Arctic hold many clues about the history of sea-ice conditions and human populations (all images courtesy of Art Dyke).Raised beaches in the Canadian Arctic hold many clues about the history of sea-ice conditions and human populations (all images courtesy of Art Dyke).
Raised beaches in the Canadian Arctic hold many clues about the history of sea-ice conditions and human populations (all images courtesy of Art Dyke).
Raised beaches in the Canadian Arctic hold many clues about the history of sea-ice conditions and human populations (all images courtesy of Art Dyke).

Raised beaches in the Canadian Arctic hold many clues about the history of sea-ice conditions and human populations (all images courtesy of Art Dyke).

Results

Bowhead Whales

Bowhead whale remains can indicate whale age at mortality as well as origin (from Pacific or Atlantic stock). The age of the remains can be approximated from radiocarbon dating.
Bowhead whale remains can indicate whale age at mortality as well as origin (from Pacific or Atlantic stock). The age of the remains can be approximated from radiocarbon dating.  Larger image

Numerous sites have been surveyed along the length of the Northwest Passage. The eastern and western approaches have become reliably ice-free in summer under historical climatic conditions, whereas in the central part summer sea ice has been persistent. The radiocarbon-dated bowhead whale remains indicate that the whales were able to range along the length of the Passage during two intervals (centered on 9000 years ago and 1000 years ago) and that they were able to access the central part from the east about 4000 years ago. During the first of these intervals (9000 before present) ice cores indicate that summer temperatures were about 3°C warmer than mid 20th Century. Therefore, a warming of 3°C exceeds the opening threshold. Medieval Warm Period temperatures were probably about 1°C warmer than mid-20th Century, which is likely close to threshold conditions for an opening of the passage.


10,000 years before present Bowhead whales enter the Norwest Passage from the Pacific (white areas are continental glacier ice cover). Larger image

9,500 years before present Bowhead whales enter from the Pacific and Atlantic, but do not yet meet. Larger image

 


9,000 years before present Pacific and Atlantic bowhead whales meet, signaling an ice-free Northwest Passage. Larger image

 


8,500 years before present Pacific and Atlantic bowheads meet, but optimum access through the passage about to end.
8,500 years before present Pacific and Atlantic bowheads meet, but optimum access through the passage about to end. Larger image
4,500 years before present Atlantic bowheads accessing the central part of the passage.
4,500 years before present Atlantic bowheads accessing the central part of the passage. Larger image

 

1, 000 years before present Atlantic and Pacific bowheads accessing the central part of the passage.
1, 000 years before present Atlantic and Pacific bowheads accessing the central part of the passage. Larger image

 


Archaeology

Early Paleoeskimo rise and fall The 'core area' of Foxe Basin east of the Northwest Passage lacked earliest Paleoeskimos, but later occupations show
Early Paleoeskimo rise and fall The 'core area' of Foxe Basin east of the Northwest Passage lacked earliest Paleoeskimos, but later occupations show "boom-and-bust" profiles (white area is continental glacier ice cover).
 Larger image

Archaeological survey results indicate that human populations reached their all-time maximums a few centuries after the region was first populated, sustained these levels for a few centuries, and then crashed to very low levels (to zero in some places) about 3,500-3,800 years ago. Subsequent population recoveries were weak in comparison to the initial peak. Whether these “boom-and-bust” population profiles were driven by climate change or by resource over-exploitation is a matter under discussion. The lack of clear correlations between the archaeological record and the bowhead record may favour the second cause.

Publications

Please note that subscriptions may be required to access some articles. To request a copy of publications, or for any more information, please contact Art Dyke.

Polyak, L., Andrews, J.T., Brigham-Grette, J., Darby, D., Dyke, A., Funder, S., Holland, M., Jennings, A., Savelle, J., Serreze, M., Wolffe, E., in review. History of sea ice in the Arctic. Chapter 8 in Past Climate Variability and Change in the Arctic and at High Latitudes. Climate Change Science Program, Synthesis and Assessment Product 1.2. United States Geological Survey.

Dyke, A.S., and Savelle, J.M. accepted. Paleoeskimo demography and sea-level history, Kent Peninsula and King William Island, central Northwest Passage, Arctic Canada. Arctic

Savelle, J.M., and Dyke, A.S. accepted. Paleoeskimo demography on western Boothia Peninsula, central Canadian Arctic. Journal of Field Archaeology

Savelle, J.M., Dyke, A.S., and Poupart, M. 2009. Kapuivik revisited: Preliminary reinterpretation of core area Paleoeskimo. In Maschner, H., Mason, O.K., and McGhee, R., eds., The Arctic World at 1100 to 1000 BP. University of Utah Press. (Expected publication August 2009)

Fisher, D., Dyke, A., Koerner, R., Bourgeois, J., Kinnard, C., Zdanowicz, C., de Vernal, A., Hillaire-Marcel, C., Savelle, J., and Rochon, A. 2006. Natural variability of Arctic sea ice over the Holocene. Eos, Transactions, American Geophysical Union 87, 273-275.

Kaufman, D.S., Ager, T.A., Anderson, N.J., Anderson, P.M., Andrews, J.T., Bartlein, P.J., Brubaker, L.B., Coats, L.L., Cwynar, L.C., Duval, M.L., Dyke, A.S., Edwards, M.E., Eisner, W.R., Gajewski, K., Geirsdóttir, A., Hu, F.S., Jennings, A.E., Kaplan, M.R., Kerwin, M.W., Lozhkin, A.V., MacDonald, G.M., Miller, G.H., Mock, C.J., Oswald, W.W., Otto-Bliesner, B.L., Porinchu, D.F., Rühland, K., Smol, J.P., Steig, E.J., and Wolfe, B.B. 2004. Holocene thermal maximum in the western Arctic (0-180°W). Quaternary Science Reviews 23: 529-560.

Dyke, A.S. and England, J. 2003. Canada’s most northerly postglacial bowhead whales (Balaena mysticetus): Holocene sea-ice conditions and polynya development. Arctic 56, 14-20.

Savelle, J.M., and Dyke, A.S. 2002. Variability in Palaeoeskimo occupation on southwestern Victoria Island, Arctic Canada: Causes and consequences. World Archaeology 33, 508-522.

Dyke, A.S., and Savelle, J.M. 2001. Holocene history of the Bering Sea bowhead whale (Balaena mysticetus) in its Beaufort Sea summer grounds off southwestern Victoria Island, western Canadian Arctic. Quaternary Research 55: 371-379.

Savelle, J.M., Dyke, A.S., and McCartney, A.P. 2000. Holocene bowhead whale (Balaena mysticetus) mortality patterns in the Canadian Arctic Archipelago. Arctic 53: 414-421.

Dyke, A.S., Hooper, J., Harington, C.R., and Savelle, J.M. 1999. The Late Wisconsinan and Holocene record of walrus (Odobenus rosmarus) from North America: A review with new data from Arctic and Atlantic Canada. Arctic 52: 160-181.

Dyke, A.S., Hooper, J., and Savelle, J.M. 1996. A history of sea ice in the Canadian Arctic Archipelago based on postglacial remains of the bowhead whale (Balaena mysticetus). Arctic 49: 235-255.