ABSTRACT: Environmental history and archaeology along the Northwest Passage.

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Abstract

The Holocene history of sea-ice along the Northwest Passage is of socio-economic interest because of its potential as a shipping lane. Both ends of the NWP reliably become clear of summer sea ice, thus providing access to the North Atlantic and North Pacific. The central parts of the NWP, however, are blocked by perennial sea ice. Building on earlier research along the eastern and western approaches, we are currently attempting to determine whether the central sea-ice plugs were permanent Holocene features, or whether they might have disappeared in warmer intervals. Current data, based on the remains of >1000 bowhead whales, support the following conclusions: (1) Both eastern and western approaches supported larger early Holocene bowhead populations during summer and fall open water periods than they did historically. (2) Early Holocene bowheads extended far beyond modern ranges. Atlantic whales reached NE Victoria Island and ranged along the east side of McClintock Channel. Pacific whales reached the north end of Prince of Wales Strait between Banks and Victoria islands and ranged eastward to at least SE Victoria Island. (3) Whales failed to enter Viscount Melville Sound throughout the Holocene. (4) Thus the southern branch of the NWP, east and south of Victoria Island, was open during the early Holocene much more commonly than it is today. However, the northern branch (western Parry Channel) appears to have retained its ice plug. (5) After an interval (8-6 ka BP) of ice conditions similar to modern conditions, bowheads re-expanded their ranges from east and west and penetrated eastern McClintock Channel between 5.5 and 3 ka BP. (6) For most of the last 3 ka, conditions have been similar to present. However, bowheads briefly ranged into McClintock Channel about 1 ka BP and abundances increased in Amundsen Gulf about the same time. These conclusions imply that the ice plug in the southern branch is close to its melting threshold, which was exceeded at times during the Holocene, most clearly during the early Holocene, when summer temperatures were about 3°C warmer than mid-20th century temperatures. Archaeological surveys conducted concurrently support the following conclusions: (1) In Amundsen Gulf and McClintock Channel, Paleoeskimo populations reached maximum levels shortly after first peopling; i.e. 4.5-3.5 ka BP. (2) Populations then crashed to near abandonment in both regions and recovered only weakly thereafter, but most prominently during Dorset time (2.5-0.5 ka). (3) Viscount Melville Sound shores remained unoccupied or very sparsely and intermittently occupied throughout. The early Paleoeskimo population peak correlates in time with the middle Holocene bowhead recurrence, but the suddenness of the subsequent crash lacks a convincing correlative in regional paleoenvironmental records, perhaps largely due to the paucity of records. Either climate forcing or resource overexploitation, or both, may have played the key role.

Bibliography of Canadian Geomorphology