Topography and permanent ice masses

The physiography of the Arctic lands is summarized in Plate 1. Much of the Arctic land area is low lying, especially western and central Siberia, the western part of the Canadian Arctic Archipelago and coastal Alaska. Mountains and high plateaus are prominent in the eastern Canadian Arctic, coastal regions bordering the Greenland Ice Sheet, interior Alaska, northeastern Siberia and Scandinavia. The highest mountain north of the Arctic Circle is Gunnbjorns Fjaeld (86.92° N, 29.87° W), which rises to 3800 m some 80 km inland from the East Greenland coast in Knud Rasmusen Land. In eastern Baffin Island there are peaks exceeding 2100 m, but in general the dissected plateaus are around 1500-1800 m elevation. On Devon and Ellesmere islands, ice caps rise to 1900-2000 m. In northern Alaska, the more or less zonally oriented Brooks Range rises to 1500-3000 m. The higher peaks in the more massive sub-Arctic Alaska Range typically exceed 3000 m. The Alaska Range contains Denali (Mount McKinley), the highest mountain in North America, with an elevation of 6194 m. There are numerous mountain ranges in northeastern Siberia. East of the Lena River there are several north-south mountain ranges. From the Arctic Circle at 140-145° E, the Momsky-Chersky ranges, with peaks rising to 2500-3100 m, stretch southeastward. The Okhotsk-Kolyma mountain ranges of Chukotka rise to 1800-2100 m.

Of the permanent ice masses (glaciers, ice caps and ice sheets), the Greenland Ice Sheet is the most prominent and is by far the largest ice mass of the Northern

Plate 1 Physiography of the Arctic lands, showing topography and major river systems (courtesy of R. Lammers, University of New Hampshire, Durham, NH). See color plates section.

Hemisphere. The ice sheet covers an area of 1.71 million km2, and contains an ice volume of 2.93 x 106 km3 (Bamber et al., 2001), which if completely melted is equivalent to a sea level rise of about 7.2 m. There is a central dome rising to 3200 m elevation and a subsidiary dome in southern Greenland. A detailed map is provided as Figure 8.1. About 40% of the ice margin area is subject to annual surface melt on average (Abdalati and Steffen, 1997). Melt does not occur at the highest elevations under present climate conditions. Further information is provided in Chapter 8. The dimensions of the other Arctic ice caps are insignificant by comparison (see Table 2.2), although they exert an influence on the local climate conditions.

In sharp contrast to the Antarctic, there are only a few small ice shelves (floating shelves of glacier ice connected to the shore) in the Arctic. The Ward Hunt Shelf extends about 100 km along the north coast of Ellesmere Island (Jeffries, 1992). It is up to 20 km wide and occupies three fiords. The shelf is 40-50 m thick and rises 4.5-6.5 m above sea level. Since the early 1900s its size has been greatly reduced and there have been many calving earlier events leading to the formation of ice islands that may drift around the Arctic Ocean for many years. An example is the ice island T-3 (also known as Fletcher's Ice Island), which was used as a platform for meteorological surveys.

Table 2.2 Major Arctic ice caps

Name/Region

Surface area (103 km3)

Devon Island 16.6

Ellesmere Island 77.2

Axel Heiberg Island 12.6

Barnes (Baffin Island) 6.0

Penny (Baffin Island) 6.0

Iceland 11.3

West Spitsbergen 36.6

Northeast Land 14

Franz Josef Land 13.7

Novaya Zemlya 23.6

Severnaya Zemlya 18.3

Greenland Ice Sheet 1710

Greenland glaciers/ice caps 48.6

Source: FromField, 1975; Govorukha, 1988; and Williams and Ferrringo, 2002

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