Polar seas
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Polar seas is a collective term for the
Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...
(about 4-5 percent of Earth's
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
s) and the southern part of the
Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...
(south of
Antarctic Convergence The Antarctic Convergence or Antarctic Polar Front is a marine belt encircling Antarctica, varying in latitude seasonally, where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the sub-Antarctic. Antarctic waters pr ...
, 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 A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
with many
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s. Among the species that inhabit various polar seas and surrounding land areas are
polar bear The polar bear (''Ursus maritimus'') is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest extant bear specie ...
,
reindeer Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...
(caribou),
muskox The muskox (''Ovibos moschatus'', in Latin "musky sheep-ox"), also spelled musk ox and musk-ox, plural muskoxen or musk oxen (in iu, ᐅᒥᖕᒪᒃ, umingmak; in Woods Cree: ), is a hoofed mammal of the family Bovidae. Native to the Arctic, i ...
,
wolverine The wolverine (), (''Gulo gulo''; ''Gulo'' is Latin for "gluttony, glutton"), also referred to as the glutton, carcajou, or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species of the family Mustelidae. It is ...
, ermine,
lemming A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also include ...
,
Arctic hare The Arctic hare (''Lepus arcticus'') is a species of hare highly adapted to living in the Arctic tundra and other icy biomes. The Arctic hare survives with shortened ears and limbs, a small nose, fat that makes up close to 20% of its body, and ...
,
Arctic ground squirrel The Arctic ground squirrel (''Urocitellus parryii'') (Inuktitut: ''ᓯᒃᓯᒃ, siksik'') is a species of ground squirrel native to the Arctic and Subarctic of North America and Asia. People in Alaska, particularly around the Aleutians, refer to ...
,
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
,
harp seal The harp seal (''Pagophilus groenlandicus''), also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus ''Phoca'' with a number ...
, and
walrus The walrus (''Odobenus rosmarus'') is a large pinniped, flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in ...
. 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 In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...
biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...
. 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. The
Arctic ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...
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 Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...
development. During summer, nearly continuous solar
insolation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...
encourages phytoplankta blooms. The Arctic Ocean is surrounded by
continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
s and has a few narrow, relatively shallow connections to the large ocean basins to the south. Large amounts of
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
ine
fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
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 A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diverge ...
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 Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
.


Antarctic

Most of
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
is covered with a thick layer of
ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
, with few species permanently living in the ice-covered areas. There are many species of
penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...
s 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. 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 The fishing industry includes any industry or activity concerned with taking, culturing, processing, preserving, storing, transporting, marketing or selling fish or fish products. It is defined by the Food and Agriculture Organization as including ...
. 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. Relatively, the Antarctic seas and
Southern ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...
surround the highest, driest, coldest and windiest continent on the earth -
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
. 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 Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
can date back to the 1820.


Role in global climate

The polar seas play an important role in the
global climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological ...
: * Carbon export/
carbon sequestration Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in land ...
: Effects concentration of
carbon dioxide in the Earth's atmosphere Carbon dioxide in Earth's atmosphere is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of several greenhouse gases in Earth's atmosphere that are contributing t ...
. *
Dimethylsulfoniopropionate Dimethylsulfoniopropionate (DMSP), is an organosulfur compound with the formula (CH3)2S+CH2CH2COO−. This zwitterionic metabolite can be found in marine phytoplankton, seaweeds, and some species of terrestrial and aquatic vascular plants ...
(DMSP/DMS) production: DMSP/DMS serves as the nucleus in
cloud formation In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may com ...
and changes the regional
albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
and
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
. *
Earth's energy budget Earth's energy budget accounts for the balance between the energy that Earth receives from the Sun and the energy the Earth loses back into outer space. Smaller energy sources, such as Earth's internal heat, are taken into consideration, but ma ...
: clouds increase albedo, sea-ice increases albedo, ice shelves increase albedo etc. * Formation of deep and bottom waters: the polar areas are the source of ocean deep and bottom cold waters. Due to the sinking of cold and dense saline waters near Greenland, and at the Antarctic Convergence, among other sites, the global ocean circulation is maintained. 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 Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone la ...
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 In radiometry, irradiance is the radiant flux ''received'' by a ''surface'' per unit area. The SI unit of irradiance is the watt per square metre (W⋅m−2). The CGS unit erg per square centimetre per second (erg⋅cm−2⋅s−1) is often used ...
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 In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
. Major nutrients (N, P, Si) are often not limiting
primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
. Blooming of
Phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...
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. 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. 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. 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. 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.


References


External links


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