A Method of Detecting Change in the Ice Conditions of the Central Greenland Sea by the Whelping Locations of Harp Seals

Abstract

Variations in the extent of sea ice within the Greenland Sea on daily, seasonal, or longer time scales are well documented, while changes in ice conditions are not. By combining historical information on the location and timing of the hunt for the whelping harp seal (Phoca groenlandica) with the ice conditions needed for the seals to give birth, details of the types, concentration, and extent of ice within the central Greenland Sea in winter have been determined for the mid- to late nineteenth century. These in turn have been compared to ice extent and concentration from the passive microwave era, as well as ice types from field work in the region. Results suggest that the ice conditions in the central Greenland Sea in the mid- to late nineteenth century were significantly different from those witnessed in recent decades. These differences manifest themselves not only in the extent of ice, but in ice types, concentration, and longevity of the ice cover. It is hypothesized that these changes could be due to an increase in both air temperature and wave energy, which is consistent with an increase in the strength and frequency of southerly and easterly winds during winter.