Polar seas

Last updated
Polar bear in Manitoba, Canada. November 2004. Polar Bear 2004-11-15.jpg
Polar bear in Manitoba, Canada. November 2004.

Polar seas is a collective term for the Arctic Ocean (about 4-5 percent of Earth's oceans) and the southern part of the Southern Ocean (south of Antarctic Convergence, about 10 percent of Earth's oceans). In the coldest years, sea ice can cover around 13 percent of the Earth's total surface at its maximum, but out of phase in the two hemispheres. The polar seas contain a huge biome with many organisms.

Contents

Among the species that inhabit various polar seas and surrounding land areas are polar bear, reindeer (caribou), muskox, wolverine, ermine, lemming, Arctic hare, Arctic ground squirrel, whale, harp seal, and walrus. [1] These species have unique adaptations to the extreme conditions. Many might be endangered if they cannot adapt to changing conditions. Contrary to popular opinion, the World Wildlife Fund studies for polar bears show that this species has prospered since 1950, attaining five times the numbers found in 1950. In general, Arctic ecosystems are relatively fragile and slow to recover from serious damage.

Arctic

A large amount of the land in the north polar region is part of Earth's tundra biome. South of the Arctic tundra, where temperatures are a little less cold, are the vast forests of conifer trees of the taiga biome. North of the Arctic tundra are polar bears and the unique marine life of the Arctic Ocean. [2]

The Arctic ocean has relatively abundant plant life. Nutrients from rivers along with mixing and upwelling from storms contribute mixed layer nutrients which are essential for Arctic phytoplankton development. During summer, nearly continuous solar insolation encourages phytoplankta blooms. The Arctic Ocean is surrounded by continents and has a few narrow, relatively shallow connections to the large ocean basins to the south. Large amounts of riverine fresh water as well as abundant nutrients (gelbstoff) flow into the Arctic basin from Siberian rivers. The widest continental shelf on the planet is found in the Arctic Ocean, extending more than 1000 kilometers outward from Siberia and Alaska. Consequently, much of the basin is very shallow. On the other hand, the Arctic Ocean contains the deepest, slowest spreading mid-ocean ridge on the planet which, until 2003, was thought to be inactive volcanically. Since then, however, a dozen active volcanoes have been discovered, illustrating the limited information available for the difficult-to-study Arctic Ocean. The numerous Siberian rivers flowing onto the shallow continental shelf freshen the seawater. These rivers have shown increased flow recently, possibly due to increased global rainfall as a result of climate change. A flow increase may raise the level of riverine nutrients. Severe Siberian drought, as experienced in 2010, could, however, decrease flows. There is an interest in a potential release of methane gas, a potent greenhouse gas, from methane clathrates present in the Arctic continental shelf sediments, if sufficient ocean warming were to occur. As much as 80% of the ocean surface is covered by ice in winter, declining to about 60% in summer; ice cover has been declining at a steady and rapid pace. A large fraction of the ice is multi-year ice, and in the far North the thickness can be more than 2m. In summer, ice tends to melt at the air-sea interface. Surface melt ponds are formed, increasing the albedo.

Antarctic

Most of Antarctica is covered with a thick layer of ice, with few species permanently living in the ice-covered areas. There are many species of penguins in the south polar region. Almost all animals in Antarctica find their food in the Southern Ocean surrounding the continent, and there is abundant marine life in the Southern Ocean. [2]

Because of the extreme but constant habitats, small disruption or damage could alter the polar systems. Although they are remote from human world, polar seas are not 'pristine' environments. Compared with the Antarctic region, the Arctic has long history of interaction with man. The polar food web structure can be sensitive to man's 'top-down' control especially with the development and growth of industrial fishing. Climate change is a natural phenomenon that influences life in polar areas. There is observational evidence that the Antarctica climate is a bellwether for climate change in the northern hemisphere, leading by about 1000 years. The study of Antarctic ice, its distribution, changes in ice volume, and other indicators of the continental climate in Antarctica are at an early stage of development and even earlier stage of understanding. Techniques for studying the terrain beneath the ice are just being explored. Lake Vostok, buried under miles of ice, has not been penetrated to date. There is evidence that it has been out of contact with the atmosphere for millions of years, making it a possible treasure trove of information.

Arctic Ocean Arctic Ocean.png
Arctic Ocean
Antarctic and Southern Ocean Southern Hemi Antarctica.png
Antarctic and Southern Ocean

Relatively, the Antarctic seas and Southern ocean surround the highest, driest, coldest and windiest continent on the earth - Antarctica. Due to the low mean temperature, there is no riverine input into the Antarctic seas. And little input DOM, POC from land. In addition to relatively thin sea ice, thick and extensive ice shelves (floating glaciers) are present in the Antarctic region. More than 90% of the sea ice is first year (annual) ice and less than 2m thick. The first confirmed sighting of Antarctica can date back to the 1820. [3]

Role in global climate

The polar seas play an important role in the global climate:

Models predict a latitudinal effect in response to climate change. These would be expected to be first obvious in polar and subpolar regions. The decline of arctic ocean summer ice coverage was assumed to be one such sign, however, the reversal of that trend leaves the question open as the origins of the now reversed 30 year trend. In 1979, the cover of Time magazine was illustrated with an image of arctic ice covering and expanding BEYOND the arctic basin, opinion seems to have little value. Real data reveal the trend of ice coverage to be on the increase. If this increase will continue, only time will tell. Developed nations ceased the production and use of chlorofluorocarbons and the atmospheric abundance and consequent ozone depletion are generally on the decrease. ozone hole Breaking-off of polar ice shelves is a continuing process with increases in Western Antarctica balanced by decreases in Eastern Antarctica. Careful study has revealed that the volume of ice in Western Antarctica was incorrectly estimated and shows no significant change attributable to climate change over the observation period.

Characteristics

Extreme oscillations in irradiance occur in these regions, for months it may be totally dark (in winter) or light (in summer). Because of the existence of polar ice, surface reflectance of sunlight is very high. In addition the solar angle are relatively quite low. So less light can penetrate into water and becomes bio available to the plants in polar water under the ice cover. Water temperatures are low, but do not change much seasonally. The low temperature and low available high irradiance together limit primary production. Major nutrients (N, P, Si) are often not limiting primary production. Blooming of Phytoplankton happens in summer, because of the decreased salinity (sea ice melt-water), lower mixing, higher stratification, higher temperature and more bio available light.

Ice is very important in structuring environment. It regulates the physics, chemistry and biology of the water column, air-sea exchange, and is also an important habitat.

Development

There is an expected rise in the exploration and development of the Polar Seas due to an increasing demand for fuel and commodities. The emergence of China and India's economy is considered one of the main drivers of this phenomenon due to an unprecedented appetite for raw materials and fuel. [5]

Presently, there are still no exact figures that define the oil and gas reserves in the Polar Seas. Initial explorations, however, have resulted in the identification of its potential. For example, Canada's explorations discovered gas and oil in several Arctic locations such as Beaufort, High Arctic (Arctic Islands), Labrador, and Newfoundland. [6] The Arctic Islands alone has an estimated 4.3 billion barrels of oil reserve while those locations that fall within the Alaskan continental shelf have potential recoverable reserves worth $18 billion. [7]

There are now 46 nations that are parties to cooperation and treaties covering the polar regions. Several of these, either individually or with partners, conduct research and explorations in the Arctic and Antarctic seas. [8] These activities are governed by international environmental protocols. However, countries like China, which faces a future oil shortage, are aggressively exploring the region for the purpose of oil extraction despite an international ban on such activity. [9]

Related Research Articles

Tundra Biome where plant growth is hindered by cold temperatures

In physical geography, tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sámi word тӯндар meaning "uplands", "treeless mountain tract". Tundra vegetation is composed of dwarf shrubs, sedges, grasses, mosses, and lichens. Scattered trees grow in some tundra regions. The ecotone between the tundra and the forest is known as the tree line or timberline. The tundra soil is rich in nitrogen and phosphorus.

Arctic Polar region of the Earths northern hemisphere

The Arctic is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Alaska, Canada, Finland, Greenland (Denmark), Iceland, Norway, Russia, and Sweden. Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost containing tundra. Arctic seas contain seasonal sea ice in many places.

Cryosphere Those portions of Earths surface where water is in solid form

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. The term deglaciation describes the retreat of cryospheric features. Cryology is the study of cryospheres.

Polar climate

The polar climate regions are characterized by a lack of warm summers. Every month in a polar climate has an average temperature of less than 10 °C (50 °F). Regions with polar climate cover more than 20% of the Earth's area. Most of these regions are far from the equator, and therefore winter days are extremely short and summer days are extremely long. In areas north of the Arctic Circle and south of the Antarctic Circle, there are days in the winter when the sun does not rise and days in the summer where the sun does not set, which result in polar night and midnight sun, respectively. A polar climate consists of long, very cold winters and short, cool summers, cool which results in treeless tundra, glaciers, or a permanent or semi-permanent layer of ice.

Climate of Antarctica Overview of the climate of Antarctica

The climate of Antarctica is the coldest on Earth. The continent is also extremely dry, averaging 166 mm (6.5 in) of precipitation per year. Snow rarely melts on most parts of the continent, and, after being compressed, becomes the glacier ice that makes up the ice sheet. Weather fronts rarely penetrate far into the continent, because of the katabatic winds. Most of Antarctica has an ice-cap climate with very cold, generally extremely dry weather.

Sea ice Ice formed from frozen seawater

Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface. Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs.

Ice shelf Large floating platform of ice caused by glacier flowing onto ocean surface

An ice shelf is a large floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland, Northern Canada, and the Russian Arctic. The boundary between the floating ice shelf and the anchor ice that feeds it is the grounding line. The thickness of ice shelves can range from about 100 m (330 ft) to 1,000 m (3,300 ft).

Ice sheet Large mass of glacial ice

In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi). The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.

Antarctic Peninsula Peninsula located in northern Antarctica

The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as the Palmer Peninsula in the US and Graham Land in the United Kingdom, is the northernmost part of the mainland of Antarctica.

West Antarctic Ice Sheet

The Western Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.

Antarctic ice sheet Polar ice cap

The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square kilometres and contains 26.5 million cubic kilometres of ice. A cubic kilometer of ice weighs approximately one metric gigaton, meaning that the ice sheet weighs 26,500,000 gigatons. Approximately 61 percent of all fresh water on the Earth is held in the Antarctic ice sheet, an amount equivalent to about 58 m of sea-level rise. In East Antarctica, the ice sheet rests on a major land mass, while in West Antarctica the bed can extend to more than 2,500 m below sea level.

Polar desert Regions of the Earth under an ice cap with very low rainfall and no vegetation; type EF under the Köppen classification

Ice deserts are the regions of Earth that fall under an ice cap climate. Despite rainfall totals low enough to normally classify as a desert, polar deserts are distinguished from true deserts by low annual temperatures and evapotranspiration. Most polar deserts are covered in ice sheets, ice fields, or ice caps.

West Antarctica Part of Antarctica that lies within the Western Hemisphere

West Antarctica, or Lesser Antarctica, one of the two major regions of Antarctica, is the part of that continent that lies within the Western Hemisphere, and includes the Antarctic Peninsula. It is separated from East Antarctica by the Transantarctic Mountains and is covered by the West Antarctic Ice Sheet. It lies between the Ross Sea, and the Weddell Sea. It may be considered a giant peninsula, stretching from the South Pole towards the tip of South America.

Polar ecology is the relationship between plants and animals in a polar environment. Polar environments are in the Arctic and Antarctic regions. Arctic regions are in the Northern Hemisphere, and it contains land and the islands that surrounds it. Antarctica is in the Southern Hemisphere and it also contains the land mass, surrounding islands and the ocean. Polar regions also contain the subantarctic and subarctic zone which separate the polar regions from the temperate regions. Antarctica and the Arctic lie in the polar circles. The polar circles are not visible on the earth but it is shown on maps to be the areas that receives less sunlight due to less radiation. These areas either receive sunlight or shade 24 hours a day because of the earth's tilt. Plants and animals in the polar regions are able to withstand living in harsh weather conditions but are facing environmental threats that limit their survival.

Nordenskjöld Coast Coast in Antarctica

The Nordenskjöld Coast is located on the Antarctic Peninsula, more specifically Graham Land, which is the top region of the Peninsula. The Peninsula is a thin, long ice sheet with an Alpine-style mountain chain. The coast consists of 15m tall ice cliffs with ice shelves.

Climate change in the Arctic Impacts of climate change on the Arctic

Climate change in the Arctic is causing major environmental issues. These range from the well known, such as the loss of sea ice or melting of the Greenland ice sheet, to more obscure, but deeply significant issues, such as permafrost thaw, social consequences for locals and the geopolitical ramifications of these changes.

Arctic Ocean Ocean in the north polar region

The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately 14,060,000 km2 (5,430,000 sq mi) and is also known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea. It has been described approximately as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing World Ocean.

Antarctica Continent

Antarctica is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,200,000 square kilometres, it is the fifth-largest continent and nearly twice the size of Australia. It is by far the least populated continent, with around 5,000 people in the summer and around 1,000 in the winter. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, which extends to all but the McMurdo Dry Valleys and the northernmost reaches of the Antarctic Peninsula.

Ice cap climate

An ice cap climate is a polar climate where no mean monthly temperature exceeds 0 °C (32 °F). The climate covers areas in or near the high latitudes to polar regions, such as Antarctica, some of the northernmost islands of Canada and Russia, Greenland, along with some regions and islands of Norway's Svalbard Archipelago that have vast deserts of snow and ice. Areas with ice cap climates are normally covered by a permanent layer of ice and have no vegetation. There is limited animal life in most ice cap climates, usually found near the oceanic margins. Although ice cap climates are inhospitable to human life, there are some small research stations scattered in Antarctica and interior Greenland.

Arctic ice pack The sea ice cover of the Arctic Ocean and its vicinity

The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall and winter. Summer ice cover in the Arctic is about 50% of winter cover. Some of the ice survives from one year to the next. Currently, 28% of Arctic basin sea ice is multi-year ice, thicker than seasonal ice: up to 3–4 m (9.8–13.1 ft) thick over large areas, with ridges up to 20 m (65.6 ft) thick. The regular seasonal cycle there has been an underlying trend of declining sea ice in the Arctic in recent decades as well.

References

  1. ↑ "ARCTIC WILDLIFE". Archived from the original on 2009-01-16.
  2. 1 2 "Life in the Polar Regions: Animals, Plants, and Others in Extreme Environments". Archived from the original on 2008-12-08.
  3. ↑ "10 years of Antarctic protection!". Archived from the original on 2008-12-22.
  4. ↑ Broeker, W. (2010). The Great Ocean Conveyor: Discovering the Trigger for Abrupt Climate Change. Princeton, New Jersey: Princeton University Press.
  5. ↑ Zellen, Barry (2009). Arctic Doom, Arctic Boom: The Geopolitics of Climate Change in the Arctic. Santa Barbara: ABC CLIO. p. 89. ISBN   9780313380129.
  6. ↑ Polar Research Board (1986). Antarctic Treaty System: An Assessment : Proceedings of a Workshop Held at Beardmore South Field Camp, Antarctica, January 7-13, 1985. Washington, D.C.: National Academies Press. p. 246. ISBN   0309036402.
  7. ↑ Polar Research Board, p. 246.
  8. ↑ United Nations Environmental Programme (2007). Global Environment Outlook: Environment for Development, GEO 4. Valletta: UNEP/Progress Press. pp.  277. ISBN   9789280728729.
  9. ↑ Brady, Anne-Marie (2012). The Emerging Politics of Antarctica. London: Routledge. p. 43. ISBN   9780415531399.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.