A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
The cryosphere is an all-encompassing term for those portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground. Thus, there is a wide overlap with the hydrosphere. The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in the global climate and in climate model response to global changes. Approximately 10% of the Earth's surface is covered by ice, but this is rapidly decreasing. The term deglaciation describes the retreat of cryospheric features. Cryology is the study of cryospheres.
Glaciology is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice.
The Kobuk River' is a river located in the Arctic region of northwestern Alaska in the United States. It is approximately 280 miles (451 km) long. Draining a basin with an area of 12,300 square miles (32,000 km2), the Kobuk River is among the largest rivers in northwest Alaska with widths of up to 1,500 feet and flow at a speed of 3–5 miles per hour in its lower and middle reaches. The average elevation for the Kobuk River Basin is 1,300 feet (400 m) above sea level, ranging from near sea level to 11,400 feet. Topography includes low, rolling mountains, plains and lowlands, moderately high rugged mountainous land, and some gently sloped plateaus and highlands. The river contains an exceptional population of sheefish, a large predatory whitefish within the salmon family, found throughout the Arctic that spawns in the river's upper reaches during the autumn. A portion of the vast Western Arctic Caribou Herd utilize the Kobuk river valley as winter range.
Glacier Bay National Park and Preserve is an American national park located in Southeast Alaska west of Juneau. President Calvin Coolidge proclaimed the area around Glacier Bay a national monument under the Antiquities Act on February 26, 1925. Subsequent to an expansion of the monument by President Jimmy Carter in 1978, the Alaska National Interest Lands Conservation Act (ANILCA) enlarged the national monument by 523,000 acres on December 2, 1980, and created Glacier Bay National Park and Preserve. The national preserve encompasses 58,406 acres of public land to the immediate northwest of the park, protecting a portion of the Alsek River with its fish and wildlife habitats, while allowing sport hunting.
Mendenhall Glacier is a glacier about 13.6 miles (21.9 km) long located in Mendenhall Valley, about 12 miles (19 km) from downtown Juneau in the southeast area of the U.S. state of Alaska. The glacier and surrounding landscape is protected as part of the 5,815 acres (2,353 ha) Mendenhall Glacier Recreation Area, a federally designated unit of the Tongass National Forest.
Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes. Most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast or slow, but is typically around 25 centimetres per day (9.8 in/d).
The Gulkana River is a 60-mile (97 km) tributary of the Copper River in the U.S. state of Alaska. Beginning near the southeastern end of Summit Lake in the Alaska Range, the river flows generally south to meet the larger river 9 miles (14 km) northeast of Glennallen. The Richardson Highway and the Trans-Alaska Pipeline run north–south, nearby and roughly parallel to the Gulkana River. Slightly south of Summit Lake the river passes under the east–west Denali Highway near its junction with the Richardson Highway at Paxson.
Taku Glacier is a tidewater glacier located in Taku Inlet in the U.S. state of Alaska, just southeast of the city of Juneau. Recognized as the deepest and thickest alpine temperate glacier known in the world, the Taku Glacier is measured at 4,845 feet (1,477 m) thick. It is about 58 kilometres (36 mi) long, and is largely within the Tongass National Forest.
Denali Highway is a lightly traveled, mostly gravel highway in the U.S. state of Alaska. It leads from Paxson on the Richardson Highway to Cantwell on the Parks Highway. Opened in 1957, it was the first road access to Denali National Park. Since 1971, primary park access has been via the Parks Highway, which incorporated a section of the Denali Highway from Cantwell to the present-day park entrance. The Denali Highway is 135 miles (217 km) in length.
Crucial to the survival of a glacier is its mass balance of which surface mass balance (SMB), the difference between accumulation and ablation. Climate change may cause variations in both temperature and snowfall, causing changes in the surface mass balance. Changes in mass balance control a glacier's long-term behavior and are the most sensitive climate indicators on a glacier. From 1980 to 2012 the mean cumulative mass loss of glaciers reporting mass balance to the World Glacier Monitoring Service is −16 m. This includes 23 consecutive years of negative mass balances.
Glacial surges are short-lived events where a glacier can advance substantially, moving at velocities up to 100 times faster than normal. Surging glaciers cluster around a few areas. High concentrations of surging glaciers occur in the Karakoram, Pamir Mountains, Svalbard, the Canadian Arctic islands, Alaska and Iceland, although overall it is estimated that only one percent of all the world's glaciers ever surge. In some glaciers, surges can occur in fairly regular cycles, with 15 to 100 or more surge events per year. In other glaciers, surging remains unpredictable. In some glaciers, however, the period of stagnation and build-up between two surges typically lasts 10 to 200 years and is called the quiescent phase. During this period the velocities of the glacier are significantly lower, and the glaciers can retreat substantially.
The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and, in the longer term, the level of the oceans. Deglaciation occurs naturally at the end of ice ages, but glaciologists find the current glacier retreat is accelerated by the measured increase of atmospheric greenhouse gases and is an effect of climate change. Mid-latitude mountain ranges such as the Himalayas, Rockies, Alps, Cascades, Southern Alps, and the southern Andes, as well as isolated tropical summits such as Mount Kilimanjaro in Africa, are showing some of the largest proportionate glacial losses. Excluding peripheral glaciers of ice sheets, the total cumulated global glacial losses over the 26 year period from 1993–2018 were likely 5500 gigatons, or 210 gigatons per yr.
The Kiwalik River is a stream on the Seward Peninsula in the U.S. state of Alaska. The headwaters of the river originate in the eastern portion of the peninsula, around Granite Mountain. The river flows north to its mouth at Kiwalik Lagoon, Chukchi Sea. The start of the 20th century mining town of Candle is found on its western bank at the confluence of Candle Creek. The ore minerals and materials found in the river basin are galena, gold, pyrite, scheelite, silver and sphalerite, and the primary commodities are tungsten, lead and zinc.
The tidewater glacier cycle is the typically centuries-long behavior of tidewater glaciers that consists of recurring periods of advance alternating with rapid retreat and punctuated by periods of stability. During portions of its cycle, a tidewater glacier is relatively insensitive to climate change.
The Tangle Lakes are a 16-mile (26 km) long chain of lakes connected by streams in interior Alaska. They form the headwaters for the Delta River.
Portage Lake is a glacial lake in the Chugach National Forest of Alaska. It sits in a long, heavily glaciated valley, and abuts the calving face of Portage Glacier at its southern end. The lake has only become visible since approximately 1914, with the rapid retreat of Portage Glacier.
Summit Lake is located above the tree line on the south slope of the Alaska Range between miles 192 and 196 of the Richardson Highway (AR-4). It is about 200 miles (320 km) north of Valdez, 180 miles (290 km) south of Fairbanks, and just south of Isabel Pass at an elevation of 3,300 feet (1,000 m). It is also situated within the northeast corner of the census-designated place of Paxson, about 15 miles (24 km) upstream (north) of Paxson Lake.
Eklutna Glacier is a land terminating glacier in Chugach State Park and the Chugach Mountains near Anchorage, Alaska. Runoff from Eklutna Glacier contributes to Eklutna Lake, the main source of drinking water for the Anchorage community as well as hydroelectric power via the Eklutna Hydroelectric Project. However, Eklutna Glacier is shrinking in response to climate change which will inevitably affect downstream water resources. Eklutna Glacier is also known by the Dena'ina name: Idlu Bena Li'a.
