The extent of summer sea ice during the 19th century, insofar as it is shown in patterns of navigability inferred from ship tracks, the direct observations of explorers, and a number of native accounts, is remarkably similar to present ice climatology. A chart of northern Canada (Figure 2) shows the routes followed by discovery expeditions and their wintering locations between 1818 and 1859, and also displays the frequency that sea ice has occurred during the recent 30-year reference period 1971–2000. It is perhaps surprising that most of the Northwest Passage was navigated during the 19th century, with expedition ships coming within 150 km of completing the passage on a number of occasions. Most significant is that even in years that were recognized as unfavorable at the time, ships were still able to reach locations that would be consistent with the worst ice conditions that have occurred during the modern reference period. Of 33 expedition or supply ships bound for the western part of Lancaster Sound between 1819 and 1859, only two failed due to unfavorable ice conditions.
Arctic Ice Conditions : The Same As 200 Years Ago
Advertisements
Advertisements