Recent Environmental Changes in ihe Arctic: A Review

Abstract

Numerous recent observations indicate that the Arctic is undergoing a significant change. In the last decade, the hydrography of the Arctic Ocean has shifted, and the atmospheric circulation has undergone a change from the lower stratosphere to the surface. Typically the eastern Arctic Ocean, on the European side of the Lomonosov Ridge, is dominated by water of Atlantic origin. A cold halocline of varying thickness overlies the warmer Atlantic water and isolates it from the sea ice and surface mixed layer. The western Arctic Ocean, on the North American side of the Lomonosov Ridge, is characterized by an added layer of water from the Pacific immediately below the surface mixed layer. Data collected during several cruises from 1991 to 1995 indicate that in the 1990s the boundary between these eastern and western halocline types shifted from a position roughly parallel to the Lomonosov Ridge to near alignment with the Alpha and Mendeleyev Ridges. The Atlantic Water temperature has also increased, and the cold halocline has become thinner. The change has resulted in increased surface salinity in the Makarov Basin. Recent results suggest that the change also includes decreased surface salinity and greater summer ice melt in the Beaufort Sea. Atmospheric pressure fields and ice drift data show that the whole patterns of atmospheric pressure and ice drift for the early 1990s were shifted counterclockwise 40°-60° from earlier patterns. The shift in atmospheric circulation seems related to the Arctic Oscillation in the Northern Hemisphere atmospheric pressure pattern. The changes in the ocean circulation, ice drift, air temperatures, and permafrost can be explained as responses to the Arctic Oscillation, as can changes in air temperatures over the Russian Arctic.