Alaska

C

Coastline

Measured roughly along its perimeter, Alaska’s coastline is 10,690 km (6,640 mi) long. However, if all the inlets and islands are taken into account, the total length is 54,563 km (33,904 mi). Along the Pacific coast, the shoreline is deeply indented. The Inside Passage, sheltered from the open ocean, is a calm body of water, but it is difficult to navigate in foggy weather. The coast of the Gulf of Alaska has tides that reach as high as 6 m (20 ft). It is buffeted by major storms, and occasionally by tsunamis caused by earthquakes under the ocean. At Cook Inlet high tide and low tide sometimes differ as much as 9 m (30 ft).

The current through the Gulf of Alaska is known as the Alaska Current. It flows westward and then, in the eastern Aleutians, turns northward to bring warm water along the western coast of Alaska all the way to Point Barrow. The coastline of the Bering Sea, except for part of the southern Seward Peninsula, is mostly shallow, with offshore bars and lagoons. Most of the coast of the Chukchi and Beaufort seas is similar. The Bering Sea contains ice during the winter, and the marginal region of the ice is one of the world’s major fisheries. In summer the ice slowly retreats northward into the Arctic Ocean, allowing navigation along the Arctic Coast by late summer.

D

Climate

Alaska has four different climatic zones: maritime, continental, transitional, and Arctic. Kodiak, the Aleutians, and southeastern and south central Alaska have a climate primarily influenced by the sea, so that temperatures do not vary greatly throughout the year, but rainfall is quite high and frequent. Western Alaska, a transitional climate, has much lower temperatures and less rainfall, but, like the Aleutians, frequent periods of extremely high winds and blowing snow. Arctic Alaska has very little snowfall, cool summer temperatures, and frequent high winds, particularly from the east. The interior has a continental climate characterized by extremely great temperature variations, but only moderate rain and snow.

The average January temperatures in southeastern Alaska are close to freezing, but snowfall in many areas can be high. Rainfall, particularly along the coasts, can exceed 2,500 mm (100 in) a year. South central Alaska has a maritime climate, ranging northward into a transitional climate. The climates of Homer and Kodiak are more similar to southeastern Alaska’s climate than to that of Anchorage. Because of the oceans and the mountains, and the storms coming from the Gulf of Alaska, this region shows considerable variation from place to place in rainfall and snowfall. For example, Thompson Pass, north of Valdez, has recorded more than 6 m (20 ft) of snowfall in one winter, whereas Anchorage often has little snow all winter long. Under proper conditions, however, cold air from the interior can cross the mountains and bring temperatures in the upper -20°s C (lower -20°s F) to this region.

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The Aleutians, dominated by perpetual low pressure systems and contrasting ocean currents, have frequent fogs, high winds or “williwaws,” and rainstorms, making the region extremely difficult for both vessel and aircraft transportation. The interior has a continental (also called sub-Arctic or taiga) climate caused by being in the rain shadow of the coast ranges and inland. Winter cold spells can last several weeks, with temperatures recorded in the -50°s C (-60°s F), while summer temperatures, particularly in the Yukon Flats, can reach into the upper 30°s C (upper 90°s F). Summers are characterized by frequent thunderstorms, which often cause forest fires. Mean annual precipitation is about 380 to 510 mm (about 15 to 20 in), with winter snowfalls varying significantly from year to year but averaging in lowland areas at about 1,300 mm (about 50 in).

Western Alaska, from the Alaska Peninsula northward to the southern Seward Peninsula, has a transitional climate, one influenced by frequent low pressure systems from the Bering Sea, but also by cold air from the interior and winter sea ice conditions. The result is summer temperatures that seldom rise much above 10°C (50°F), and winter conditions characterized by high winds and snow storms. Arctic Alaska, stretching from the northern Seward Peninsula (Kotzebue Sound) northward to Barrow and eastward to Demarcation Point, has an Arctic climate characterized by low winter and summer temperatures and frequent high winds. While snowfall is low, generally less than 300 mm (12 in), blowing snow frequently creates a condition known as whiteout, in which people cannot differentiate between land and sky, making it extremely easy to become disoriented and lost. Summers are cool, with temperatures generally less than 10°C (50°F) and rainfall tends to concentrate in late summer. The high winds along the coast of the Beaufort Sea blow away insects and make the area favorable to caribou in the summer months.

Because of Alaska’s high northern latitude, the length of day varies much more between summer and winter than it does in other parts of the United States. At Fort Yukon, on the Arctic Circle, the sun barely rises above the southern horizon on the shortest day of the year, December 21. At Barrow, on the Arctic Coast, the sun is not seen from late November until late January. In summer the days are much longer and Alaska is as much “the land of the midnight sun” as are Norway and Sweden. At Barrow there is continuous daylight from early May to early August.

E

Soils

Most Alaska soils are immature, cold, and acidic. Except for the lowlands of southeastern and south central Alaska, and portions of the lowlands in the Interior, most Alaska soils are permanently frozen, a condition called permafrost. At a certain depth in the ground, the soil remains perpetually frozen. This level is known as the permafrost table and the ground beneath is known as the inactive layer because it never thaws. The soil above, however, freezes and thaws every year, and in the process the soil is constantly churned. The permafrost table is impervious to water. Therefore the surface in much of the Interior, western, and Arctic Alaska is waterlogged and contains numerous but usually shallow lakes often called thaw lakes, in spite of the region’s low precipitation. Thaw lakes form when large blocks of ground ice contained in the inactive layer thaw and leave a hole in the surface, which fills with water. On the Arctic coastal plain these lakes are generally rectangular in shape, whereas in the Interior and western Alaska they are usually oval in form. Such lakes fill in with vegetation over time, and in the Interior eventually with trees. Thus the lakes are not permanent, but are constantly changing, with new lakes forming and others being filled in with vegetation. About 80 percent of Alaska contains permanently frozen ground. Of this, over half is called continuous permafrost, that is, has an active layer of only a few inches to a foot or so in depth. The remainder is called discontinuous permafrost, where the active layer may be many feet in depth.

F

Plant Life

Forests cover 34 percent of Alaska’s land area. The most important commercial species of trees are birch, Sitka spruce (the state tree), western hemlock, black spruce, and white spruce.

The Alaska Panhandle is a land of forests. The mild climate and heavy rainfall promote dense tree growth. The huge Tongass National Forest is an area where young saplings compete for space with trees that are centuries old. Trees found there include the western hemlock, Sitka spruce, canoe cedar, and yellow cedar (also called Alaska cedar), which are all conifers. The forest floor is carpeted with berry-producing plants and moss.

South central Alaska south of the Alaska Range is also heavily forested, but the trees are usually smaller and there is a transition from Sitka spruce to white and black spruce. The largest stand of timber is in the Chugach National Forest.

Southwestern Alaska is almost entirely treeless, except for Sitka spruce and some cottonwood on Kodiak Island and a few stunted birches and willows found in the Aleutian Islands. However, grasses grow luxuriantly in the cool wet climate. Flowers bloom in great variety and include the forget-me-not (the state flower), anemone, lupine, paintbrush, and marsh marigold in boggy areas, and the dwarf rhododendron on the hillsides.

In the Interior region, vegetation must adapt itself to short, warm summers and long, cold winters. Trees grow slowly, and their root systems must be shallow because they cannot penetrate the permafrost. Toward the west the trees become sparse and are replaced by wet tundra. Similarly, the mountain slopes contain tundra in the Interior. Cleared areas are often brilliant with fireweed in the summer months. Principal trees found in this region are black and white spruce, paper birch, tamarack, aspen, Alaskan larch, and balsam poplar. There are expanses of bogs called muskeg, and grasslands, where many species of wild flowers, berries, and shrubs occur.

Arctic Alaska contains primarily tundra vegetation with tall brush and some forests in stream valleys. Tundra consists of mosses, lichens, and grasses 3 to 5 cm (1 to 2 in) high, sedges and heather up to 20 cm (8 in) high, and willows taller than an average adult person. Tundra is characteristic of the northlands around the Arctic Ocean and of other areas in Alaska above the timberline. Colorful flowers carpet the tundra during the brief summer weeks when the sun never sets, and plants grow well although the soil thaws less than 30 cm (1 ft) before the long winter returns. Here and there, dwarf willows are found.

G

Animal Life

In southeastern Alaska are found the black bear, grizzly bear, black-tailed deer, moose, mountain goat, marten, red fox, mink, wolf, coyote, otter, and beaver. The sea lion, harbor seal, sea otter, porpoise, and several species of whale are common along the coast. Halibut, herring, cod, crab, and shrimp are also found in abundance in coastal waters. Several species of anadromous (living in both salt and freshwater) fish occur in Alaska, including chinook, coho, sockeye, chum, and pink salmon, Dolly Varden, sheefish, and rainbow and cutthroat trout. Brook and lake trout, Arctic grayling, northern pike, whitefish, and burbot occur in the state’s lakes and streams. Wildlife in south-central Alaska is similar to that of the Panhandle, with the addition of Dall sheep and caribou. In southwestern Alaska is rugged Kodiak Island, the home of the Kodiak brown bear, which is believed to be the largest omnivorous land animal in the world.

The Dall sheep, grizzly bear, moose, wolf, and caribou are found in Denali National Park and Preserve. Gulls, kittiwakes, cormorants, murres, puffins, and other seabirds are found throughout the Aleutian Islands. On the Pribilof Islands are extensive fur seal rookeries and also small colonies of sea otter.

The Interior region is the home of caribou, moose, Dall sheep, mountain goat, bison, wolf, black bear, grizzly bear, and many fur-bearing animals. Thousands of migratory waterfowl arrive at the end of April at their nesting grounds along the lower Yukon and Kuskokwim river valleys and leave in August and September for warmer lands farther south. The Bristol Bay area of the Bering Sea coast is noted for its salmon.

In the Arctic region the sea ice is the habitat of the polar bear, hair seal, and walrus. Marine life is abundant and ranges from tiny crustaceans to giant whales. Caribou graze on the tundra, migrating in herds and returning for the winter to range south of the Brook Range. The Arctic is a major nesting area for waterfowl, shorebirds, and many raptors, including peregrine falcons.

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