ecomii - a better way
April 19, 2014  |  Login
Arctic and subarctic islands

Defined primarily by climatic rather than latitudinal criteria, arctic islands are those in the Norhern Hemisphere where the mean temperature of the warmest month does not exceed 50°F (10°C) and that of the coldest is not above 32°F (0°C). Subarctic islands are those in the Northern Hemisphere where the mean temperature of the warmest month is over 50°F (10°C) for less than 4 months and that of the coldest is less than 32°F (0°C). Such islands generally are in high latitudes. Distribution of land and sea masses, ocean currents, and atmospheric circulation greatly modifies the effect of latitude so that it is often misleading to use location relative to the Arctic Circle as a significant criterion of arctic or subarctic. The largest proportion by area of the islands lies in the Western Hemisphere, primarily in Greenland and in the Canadian Arctic Archipelago. Within this general description, individual islands vary considerably (see table).

Size of larger arctic and subarctic Islands*

 

Area

Name

mi2

km2

Aleutian Is.

Unimak I.

15,500

40,100

Unalaska I.

10,800

28,000

St. Lawrence I.

18,200

47,100

Nunivak I.

16,000

41,400

Kodiak I.

37,400

96,900

Canadian Arctic Archipelago

500,000

1,295,000

Baffin I.

196,000

507,000

Ellesmere I.

76,000

197,000

Victoria

84,000

217,000

Banks

27,000

70,000

Devon

21,000

55,000

Axel Heiberg

17,000

43,000

Melville

16,000

42,000

Southhampton

16,000

42,000

Prince of Wales

13,000

33,033

Newfoundland

42,734

109,000

Greenland

840,000

2,176,000

Iceland

39,961

102,000

Svalbard (archipelago)

24,100

62,000

Vest-Spitsbergen

15,250

39,000

Franz Josef Land (archipelago)

7,000

18,000

Novaya Zemlya (archipelago)

36,000

93,000

Severny I.

21,000

54,000

Yughny I.

15,000

39,000

Severnaya Zemlya (archipelago)

14,000

36,000

New Siberian Is.

12,000

31,000

Wrangel I.

2,000

5,000

Sakhalin I.

27,000

70,000

Kuriloe Is.

6,000

16,000

*Approximate only in some cases because of incomplete mapping.

Physiographically, the islands include all the varied major landforms found elsewhere in the world, from rugged mountains over 8000 ft (2500 m) high, through plateaus and hills, to level plains only recently emerged from the sea. All have been glaciated except Sakhalin and some of the islands in the Bering Sea sector. Removal of the weight of ice sheets and the resultant crustal rebound has exposed prominent marine beaches and wave-cut cliffs on many of the islands. These now commonly occur at elevations of over 300 ft (150 m) above sea level.

The general climatic pattern of these islands is set by their location relative to the two semipermanent centers of low pressure over the Aleutian Islands and over Iceland. Most of the precipitation is cyclonic in origin. Because they are marine areas, the islands receive more precipitation than they otherwise would, yet even so this is very light for most of the arctic islands removed from the zone of cyclonic activity. Also, because they are marine areas, the islands, regions of low temperatures by definition, are not regions of extreme low temperatures. In general, the larger the island and the closer its proximity to a continental landmass, the higher are the summer temperatures and the lower its winter temperature. Polar meteorology

The climatic differences between arctic and subarctic islands are reflected in their natural vegetation. The arctic islands are treeless. Natural vegetation consists of the tundra—mosses, sedges, lichens, grasses, and creeping shrubs. Bare ground is often exposed and in some places plant growth may be lacking completely except for a few rock-encrusting lichens. In such places the ground surface may consist of frost-shattered rock fragments, tidal mud flats, boulder-strewn fell fields, or snow patches and ice. Permafrost (permanently frozen ground) occurs throughout the Arctic (and in parts of the subarctic) and is reflected in impeded drainage and patterned ground. Permafrost Tundra

The natural vegetation of subarctic islands characteristically is the boreal forest or taiga, composed predominantly of conifers such as spruce, fir, pine, and larch with deciduous trees such as birch, aspen, and willow; the latter are especially common in regrowth of clearings in the forest. Impeded drainage because of permafrost or glaciation gives rise to numerous ponds and muskeg areas. A transitional type of vegetation, the forest-tundra, is recognized on some subarctic islands in sectors where smaller trees are widely spaced and abundant mosses cover the ground. Muskeg Taiga

The typical soils of the subarctic islands are podzols—the grayish-white surface soil beneath the raw humus layer and highly acidic in nature. The tundra soils of the arctic islands really consist only of a dark-brown peaty surface layer over poorly defined thin horizons, and much of the ground cannot properly be termed soil.

 Back to all terms
From McGraw-Hill Concise Encyclopedia of Environmental Science. The Content is a copyrighted work of McGraw-Hill and McGraw-Hill reserves all rights in and to the Content. The Work is © 2008 by The McGraw-Hill Companies, Inc.
 
 
 
 
ecomii featured poll

Vote for your Favorite Charity

 

 

 
 
ecomii resources
 
ecomii Tips Newsletter 

Sign up today to receive a weekly tip for living greener

 
Get in Touch

Got suggestions? Want to write for us? See something we could improve? Let us know!