1.
Shelf ice
–
Shelf ice can refer to the ice that forms when a portion of a lake surface freezes. It is often then washed upon the shore, the phenomenon is common within the Great Lakes. Shelf ice forms from float ice, float ice is like drift ice, but seldom becomes large enough to support humans or large animals. The cold temperatures freeze small areas of the lake, forming float ice. Similar ice will form along the shoreline when the lake is calm, over time, the ice will build up from continued freezing on the open lake and from snow accumulation on the surface. The surface of the Great Lake seldom remains calm enough for the surface to freeze. Note, The smaller lakes, Lake St. Clair, Lake Erie, the wind pushes the float ice and creates waves which also move the ice. Over time, the ice will accumulate on the shores of the lake. Like sand, which is moved by the wind and the waves, when pushed onto the beach, it remains and over time, the ice accumulates on top of the beach and the ice already pushed ashore. On days with a strong wind, an ice sheet may reach out into the lakes as far as the eye can see. But across the lake, there is likely to be open water several miles wide, shelf ice is a floating mat of ice, but unlike a pond or a small lake that freezes over, the shelf is not a uniform sheet of ice. Created by the wind and waves, the ice is a jumble of ice chunks. It is as if you took a pile of rubble and pushed up against a wall, the more you push, the narrow the pile becomes, and it rises in a ridge. But there is nothing stable in the pile, the individual pieces are not initially connected, they only float upon the water surface and rest upon each other. Many become jammed together but throughout the structure, there are pockets of air, since each piece of ice developed independently, each is of a different thickness, creating variations in strength, density, and depth. Over time, the ‘shelf’ extends out from the shore in a long-lasting floating ledge, the ledge can become very thick depending on the size of the ice pieces and the size of the air pockets. Therefore, an ice shelf can vary from a flat surface to a jumbled pile of blocks with parallel ridges. When a ‘shelf’ extends out to a bar, a ridge will form that is higher than the rest of the shelf
Shelf ice
–
Shelf ice along the southern Lake Michigan Shoreline at Indiana Dunes National Lakeshore
Shelf ice
–
Southern Lake Michigan beach in winter at Indiana Dunes National Lakeshore
Shelf ice
–
An unbroken stretch of shelf ice at Indiana Dunes National Lakeshore
Shelf ice
–
Ridges of shelf ice along Lake Michigan's southern shore at Indiana Dunes National Lakeshore
2.
Antarctic Sound
–
The Antarctic Sound is a body of water about 30 nautical miles long and from 7 to 12 nautical miles wide, separating the Joinville Island group from the northeast end of the Antarctic Peninsula. Since 2005 cruise ships have been visiting the area, the northern limit of the sound, where it joins the Bransfield Strait, is the line connecting Cape Dubouzet on Trinity Peninsula with Turnbull Point on DUrville Island. The southern limit is the line connecting Cape Scrymgeour on Andersson Island with Cape Purvis on Dundee Island, the sound is 30 nautical miles long and from 7 to 12 nautical miles wide. The Tabarin Peninsula forms the southwestern coast of the Antarctic Sound and contains several bays, the Antarctic Sound was first navigated by the vessel Antarctic belonging to the Swedish Antarctic Expedition of 1902, captained by Otto Nordenskjöld. Hope Bay was at one time the site of a British base, Hope Bay has been recognised as an Important Bird Area. Birds that breed here include the gentoo penguin, brown skua, Antarctic tern, Wilsons storm petrel, kelp gull and it also houses one of the largest breeding colonies of Adélie penguin in Antarctica. At Trepassey Bay, gentoo and Adélie penguins also breed, as well as Cape petrels, snow petrels, skuas, weddell seals often haul out on the beach and leopard seals hunt offshore. This article incorporates public domain material from the United States Geological Survey document Antarctic Sound
Antarctic Sound
–
Antarctic Sound
3.
Glacier
–
A glacier is a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs and they also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice, between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earths land surface, continental glaciers cover nearly 13,000,000 km2 or about 98 percent of Antarcticas 13,200,000 km2, with an average thickness of 2,100 m. Greenland and Patagonia also have huge expanses of continental glaciers, Glacial ice is the largest reservoir of fresh water on Earth. Within high altitude and Antarctic environments, the temperature difference is often not sufficient to release meltwater. A large piece of compressed ice, or a glacier, appears blue as large quantities of water appear blue and this is because water molecules absorb other colors more efficiently than blue. The other reason for the color of glaciers is the lack of air bubbles. Air bubbles, which give a color to ice, are squeezed out by pressure increasing the density of the created ice. The word Glaceon is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, the processes and features caused by or related to glaciers are referred to as glacial. The process of establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology, Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, and behavior, cirque glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, a large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have a less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called ice sheets or continental glaciers, several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces, the only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of water, enough that if both melted, global sea levels would rise by over 70 m
Glacier
–
The
Baltoro Glacier in the
Karakoram,
Baltistan, Northern Pakistan. At 62 kilometres (39 mi) in length, it is one of the longest alpine glaciers on earth.
Glacier
–
Ice calving from the
terminus of the
Perito Moreno Glacier in western
Patagonia, Argentina
Glacier
–
The
Aletsch Glacier, the largest glacier of the
Alps, in Switzerland
Glacier
–
The
Quelccaya Ice Cap is the largest glaciated area in the
tropics, in Peru
4.
Ice sheet
–
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km2, thus also known as continental glacier. Ice sheets are bigger than ice shelves or alpine glaciers, masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery, although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams, the present-day polar ice sheets are relatively young in geological terms. The Antarctic Ice Sheet first formed as an ice cap in the early Oligocene, but retreating and advancing many times until the Pliocene. The Greenland ice sheet did not develop at all until the late Pliocene and this had the unusual effect of allowing fossils of plants that once grew on present-day Greenland to be much better preserved than with the slowly forming Antarctic ice sheet. The Antarctic ice sheet is the largest single mass of ice on Earth and it covers an area of almost 14 million km2 and contains 30 million km3 of ice. Around 90% of the water on the Earths surface is held in the ice sheet. The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05 °C/decade since 1957, the Antarctic ice sheet is divided by the Transantarctic Mountains into two unequal sections called the East Antarctic ice sheet and the smaller West Antarctic Ice Sheet. The EAIS rests on a land mass but the bed of the WAIS is, in places. It would be seabed if the ice sheet were not there, the WAIS is classified as a marine-based ice sheet, meaning that its bed lies below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, the Greenland ice sheet occupies about 82% of the surface of Greenland, and if melted would cause sea levels to rise by 7.2 metres. Estimated changes in the mass of Greenlands ice sheet suggest it is melting at a rate of about 239 cubic kilometres per year and these measurements came from NASAs Gravity Recovery and Climate Experiment satellite, launched in 2002, as reported by BBC News in August 2006. Ice movement is dominated by the motion of glaciers, whose activity is determined by a number of processes and their motion is the result of cyclic surges interspersed with longer periods of inactivity, on both hourly and centennial time scales. The Greenland, and probably the Antarctic, ice sheets have been losing mass recently, because losses by melting, the IPCC projects that ice mass loss from melting of the Greenland ice sheet will continue to outpace accumulation of snowfall. Accumulation of snowfall on the Antarctic ice sheet is projected to outpace losses from melting, understanding of these processes is limited and there is no consensus on their magnitude. More research work is required to improve the reliability of predictions of ice-sheet response on global warming
Ice sheet
–
A
satellite composite image of
Antarctica
Ice sheet
–
Aerial view of the ice sheet on
Greenland 's east coast
5.
Coast
–
A coastline or a seashore is the area where land meets the sea or ocean, or a line that forms the boundary between the land and the ocean or a lake. A precise line that can be called a coastline cannot be determined due to the Coastline paradox, the term coastal zone is a region where interaction of the sea and land processes occurs. Both the terms coast and coastal are often used to describe a location or region, for example, New Zealands West Coast. Edinburgh for example is a city on the coast of Scotland, a pelagic coast refers to a coast which fronts the open ocean, as opposed to a more sheltered coast in a gulf or bay. A shore, on the hand, can refer to parts of the land which adjoin any large body of water, including oceans. Similarly, the related term refers to the land alongside or sloping down to a river or to a body of water smaller than a lake. Bank is also used in parts of the world to refer to an artificial ridge of earth intended to retain the water of a river or pond. According to the UN atlas, 44% of people live within 150 kilometres of the sea, tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, the tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves, however, tidal bores can erode as the waves surge up river estuaries from the ocean. Waves erode coastline as they break on shore releasing their energy, the larger the wave the more energy it releases and the more sediment it moves. Coastlines with longer shores have more room for the waves to disperse their energy, while coasts with cliffs and short shore faces give little room for the wave energy to be dispersed. In these areas the wave energy breaking against the cliffs is higher, sediment deposited by waves comes from eroded cliff faces and is moved along the coastline by the waves. This forms an abrasion or cliffed coast, sediment deposited by rivers is the dominant influence on the amount of sediment located on a coastline. Today riverine deposition at the coast is often blocked by dams and other human regulatory devices, like the ocean which shapes them, coasts are a dynamic environment with constant change. The coast and its adjacent areas on and off shore are an important part of a local ecosystem, Salt marshes and beaches also support a diversity of plants, animals and insects crucial to the food chain. The high level of biodiversity creates a level of biological activity. More and more of the people live in coastal regions
Coast
–
Rugged coastline of the
West Coast Region of
New Zealand
Coast
–
Atlantic rocky coastline, showing a surf area. Porto Covo, west coast of Portugal
Coast
–
Somalia has the longest coastline in Africa
Coast
–
A settled coastline in
Marblehead, Massachusetts. Once a fishing port, the harbor is now dedicated to tourism and pleasure boating. Observe that the sand and rocks have been darkened by oil slick up to the high-water line.
6.
Antarctica
–
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 14,000,000 square kilometres, it is the fifth-largest continent, for comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km in thickness, Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, vegetation, where it occurs, is tundra. The continent, however, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources. In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north. For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
Antarctica
–
Adelie penguins in Antarctica
Antarctica
–
Antarctica
Antarctica
–
Painting of
James Weddell 's second expedition in 1823, depicting the brig Jane and the cutter Beaufroy.
Antarctica
–
Nimrod Expedition South Pole Party (left to right):
Wild,
Shackleton,
Marshall and
Adams
7.
Greenland
–
Greenland is an autonomous constituent country within the Danish Realm between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for more than a millennium. The majority of its residents are Inuit, whose ancestors began migrating from the Canadian mainland in the 13th century, Greenland is the worlds largest island. Three-quarters of Greenland is covered by the permanent ice sheet outside Antarctica. With a population of about 56,480, it is the least densely populated country in the world, the Arctic Umiaq Line ferry acts as a lifeline for western Greenland, connecting the various cities and settlements. Greenland has been inhabited off and on for at least the last 4,500 years by Arctic peoples whose forebears migrated there from what is now Canada, Norsemen settled the uninhabited southern part of Greenland beginning in the 10th century, and Inuit peoples arrived in the 13th century. The Norse colonies disappeared in the late 15th century, soon after their demise, beginning in 1499, the Portuguese briefly explored and claimed the island, naming it Terra do Lavrador. In the early 18th century, Scandinavian explorers reached Greenland again, to strengthen trading and power, Denmark-Norway affirmed sovereignty over the island. Greenland was settled by Vikings more than a thousand years ago, Vikings set sail from Greenland and Iceland, discovering North America nearly 500 years before Columbus reached Caribbean islands. Though under continuous influence of Norway and Norwegians, Greenland was not formally under the Norwegian crown until 1262, the Kingdom of Norway was extensive and a military power until the mid-14th century. Thus, the two kingdoms resources were directed at creating Copenhagen, Norway became the weaker part and lost sovereignty over Greenland in 1814 when the union was dissolved. Greenland became a Danish colony in 1814, and was made a part of the Danish Realm in 1953 under the Constitution of Denmark, in 1973, Greenland joined the European Economic Community with Denmark. However, in a referendum in 1982, a majority of the population voted for Greenland to withdraw from the EEC which was effected in 1985, Greenland contains the worlds largest and most northernly national park, Northeast Greenland National Park. Greenland is divided into four municipalities - Sermersooq, Kujalleq, Qaasuitsup and it also retains control of monetary policy, providing an initial annual subsidy of DKK3.4 billion, which is planned to diminish gradually over time. Greenland expects to grow its economy based on increased income from the extraction of natural resources, the capital, Nuuk, held the 2016 Arctic Winter Games. At 70%, Greenland has one of the highest shares of renewable energy in the world, the early Viking settlers named the island as Greenland. In the Icelandic sagas, the Norwegian-born Icelander Erik the Red was said to be exiled from Iceland for manslaughter, along with his extended family and his thralls, he set out in ships to explore an icy land known to lie to the northwest. After finding an area and settling there, he named it Grœnland
Greenland
–
Kingittorsuaq Runestone from
Kingittorsuaq Island (
Middle ages).
Greenland
–
Flag
Greenland
–
The last written records of the
Norse Greenlanders are of a marriage in 1408 in the
church of Hvalsey —today the best-preserved Nordic ruins in Greenland.
Greenland
–
A 1747 map based on Egede's descriptions and misconceptions.
8.
Russian Arctic
–
The Extreme North or Far North is a large part of Russia located mainly north of the Arctic Circle and boasting enormous mineral and natural resources. Its total area is about 5,500,000 square kilometres, due to the harsh conditions of the area, people who work there have traditionally been entitled by the Russian government to higher wages than workers of other regions. Murmansk, Yakutsk, Norilsk, Novy Urengoi, and Magadan are the largest cities within the Russian Far North proper, the larger and more southern Arkhangelsk is the largest among cities and territories equated to the Far North. The Far North is known for its harsh climate. People who work there, other indigenous populations involved in traditional occupations. Additional benefits include extra vacation, extra disability benefits, extra retirement benefits, such compensation had begun under the policy of the Soviet Union, and has been maintained by the Russian Federation. The regions were established based on climate, with harsher regions garnering greater compensation relative to milder regions. Russian Far East List of Russian explorers Small-numbered indigenous peoples of Extreme North Northern Sea Route
Russian Arctic
–
The Extreme North
9.
Sea ice
–
Sea ice arises as seawater freezes. Because ice is less dense water, it floats on the oceans surface. Sea ice covers about 7% of the Earth’s surface and about 12% of the world’s oceans. Much of the sea ice is enclosed within the polar ice packs in the Earths polar regions, the Arctic ice pack of the Arctic Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, 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. Sea ice does not simply grow and melt, during its lifespan, it is very dynamic. Due to the action of winds, currents, water temperature. Sea ice is classified according to whether or not it is able to drift, Sea ice can be classified according to whether or not it is attached to the shoreline. If attached, it is called landfast ice, or more often, alternatively, and unlike fast ice, drift ice occurs further offshore in very wide areas, and encompasses ice that is free to move with currents and winds. The physical boundary between fast ice and drift ice is the fast ice boundary, the drift ice zone may be further divided into a shear zone, a marginal ice zone and a central pack. Drift ice consists of floes, individual pieces of sea ice 20 metres or more across, the term pack ice is used either as a synonym to drift ice, or to designate drift ice zone in which the floes are densely packed. The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation, another classification used by scientists to describe sea ice is based on age, that is, on its development stages. These stages are, new ice, nilas, young ice, first-year, new ice is a general term used for recently frozen sea water that does not yet make up solid ice. It may consist of ice, slush, or shuga. Other terms, such as ice and pancake ice, are used for ice crystal accumulations under the action of wind. Nilas designates a sea ice crust up to 10 centimetres in thickness and it bends without breaking around waves and swells. Nilas can be subdivided into dark nilas – up to 5 centimetres in thickness and very dark
Sea ice
–
Broken pieces of sea ice with a snow cover.
Sea ice
–
Nilas in
Baffin Bay
Sea ice
–
Aerial view showing an expanse of drift ice offshore Labrador (Eastern Canada) displaying floes of various sizes loosely packed, with open water in several networks of
leads. (Scale not available.)
Sea ice
–
Aerial view showing an expanse of drift ice in southeastern Greenland, comprising loosely packed floes of various sizes, with a
lead developing in the centre.(Scale not available.)
10.
Arctic Ocean
–
The Arctic Ocean is the smallest and shallowest of the worlds five major oceans. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean, located mostly in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter, the summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center uses satellite data to provide a record of Arctic sea ice cover. The Arctic may become ice free for the first time in human history within a few years or by 2040, for much of European history, the north polar regions remained largely unexplored and their geography conjectural. He was probably describing loose sea ice known today as growlers or bergy bits, his Thule was probably Norway, early cartographers were unsure whether to draw the region around the North Pole as land or water. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank and this lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an Open Polar Sea was persistent, john Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this. In the United States in the 1850s and 1860s, the explorers Elisha Kane, even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea. Nevertheless, as all the explorers who travelled closer and closer to the reported, the polar ice cap is quite thick. Fridtjof Nansen was the first to make a crossing of the Arctic Ocean. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard, with air support. The first nautical transit of the pole was made in 1958 by the submarine USS Nautilus. Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean, scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes. In World War II, the European region of the Arctic Ocean was heavily contested, the Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2, almost the size of Antarctica. The coastline is 45,390 km long and it is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea, countries bordering the Arctic Ocean are, Russia, Norway, Iceland, Greenland, Canada and the United States. There are several ports and harbours around the Arctic Ocean In Alaska, in Canada, ships may anchor at Churchill in Manitoba, Nanisivik in Nunavut, Tuktoyaktuk or Inuvik in the Northwest territories
Arctic Ocean
–
A
bathymetric /
topographic of the Arctic Ocean and the surrounding lands.
Arctic Ocean
–
Emanuel Bowen 's 1780s map of the Arctic features a "Northern Ocean".
Arctic Ocean
–
Sea cover in the Arctic Ocean, showing the median, 2005 and 2007 coverage
Arctic Ocean
–
Three
polar bears approach
USS Honolulu near the
North Pole.
11.
Southern Ocean
–
As such, it is regarded as the fourth-largest of the five principal oceanic divisions, smaller than the Pacific, Atlantic, and Indian Oceans but larger than the Arctic Ocean. This ocean zone is cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters. By way of his voyages in the 1770s, Captain James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Oceans northern boundary or even existence, considering the part of the Pacific, Atlantic. Others regard the seasonally-fluctuating Antarctic Convergence as the natural boundary, Borders and names for oceans and seas were internationally agreed when the International Hydrographic Bureau, the precusor to the IHO, convened the First International Conference on 24 July 1919. The IHO then published these in its Limits of Oceans and Seas, Australian authorities regard the Southern Ocean as lying immediately south of Australia. Map publishers using the term Southern Ocean on their maps include Hema Maps, Southern Ocean is an obsolete name for the Pacific Ocean or South Pacific, coined by Vasco Núñez de Balboa, the first European to discover it, who approached it from the north. The South Seas is an archaic synonym. A1745 British Act of Parliament established a prize for discovering a Northwest Passage to the Western and Southern Ocean of America, authors using Southern Ocean to name the waters encircling the unknown southern polar regions used varying limits. James Cooks account of his second voyage implies New Caledonia borders it, peacocks 1795 Geographical Dictionary said it lay to the southward of America and Africa, John Payne in 1796 used 40 degrees as the northern limit, the 1827 Edinburgh Gazetteer used 50 degrees. The United Kingdoms South Australia Act 1834 described the waters forming the southern limit of the new colony of South Australia as the Southern Ocean. The Colony of Victorias Legislative Council Act of 1881 delimited part of the division of Bairnsdale as along the New South Wales boundary to the Southern ocean. The limit then followed the west coast of Tasmania southwards to the South East Cape and then went eastwards to Broughton Island, New Zealand, the northern limits of the Southern Ocean were moved southwards in the IHOs 1937 second edition of the Limits of Oceans and Seas. From this edition, much of the northern limit ceased to abut land masses. As is discussed in detail below, prior to the 2002 edition the limits of oceans explicitly excluded the seas lying within each of them. The Great Australian Bight was unnamed in the 1928 edition, and it therefore encompassed former Southern Ocean waters but was technically not inside any of the three adjacent oceans by 1937. To perform direct comparisons of current and former limits of oceans it is necessary to consider, or at least be aware of, the limits of the Atlantic, Pacific and Indian Oceans have therefore been extended South to the Antarctic Continent. The IHO readdressed the question of the Southern Ocean in a survey in 2000, of its 68 member nations,28 responded, and all responding members except Argentina agreed to redefine the ocean, reflecting the importance placed by oceanographers on ocean currents
Southern Ocean
–
1928 First Edition of Limits of Oceans and Seas with original IHO delineation of Southern Ocean abutting land-masses.
Southern Ocean
–
Earth's oceans
Southern Ocean
–
1937 Second Edition of Limits of Oceans and Seas showing IHO's pre-1953 delineation of Southern Ocean moved southwards.
Southern Ocean
–
1564 Typus Orbis Terrarum, a map by
Abraham Ortelius showed the imagined link between the proposed continent of Antarctica and
South America.
12.
Gravity
–
Gravity, or gravitation, is a natural phenomenon by which all things with mass are brought toward one another, including planets, stars and galaxies. Since energy and mass are equivalent, all forms of energy, including light, on Earth, gravity gives weight to physical objects and causes the ocean tides. Gravity has a range, although its effects become increasingly weaker on farther objects. The most extreme example of this curvature of spacetime is a hole, from which nothing can escape once past its event horizon. More gravity results in time dilation, where time lapses more slowly at a lower gravitational potential. Gravity is the weakest of the four fundamental interactions of nature, the gravitational attraction is approximately 1038 times weaker than the strong force,1036 times weaker than the electromagnetic force and 1029 times weaker than the weak force. As a consequence, gravity has an influence on the behavior of subatomic particles. On the other hand, gravity is the dominant interaction at the macroscopic scale, for this reason, in part, pursuit of a theory of everything, the merging of the general theory of relativity and quantum mechanics into quantum gravity, has become an area of research. While the modern European thinkers are credited with development of gravitational theory, some of the earliest descriptions came from early mathematician-astronomers, such as Aryabhata, who had identified the force of gravity to explain why objects do not fall out when the Earth rotates. Later, the works of Brahmagupta referred to the presence of force, described it as an attractive force. Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and this was a major departure from Aristotles belief that heavier objects have a higher gravitational acceleration. Galileo postulated air resistance as the reason that objects with less mass may fall slower in an atmosphere, galileos work set the stage for the formulation of Newtons theory of gravity. In 1687, English mathematician Sir Isaac Newton published Principia, which hypothesizes the inverse-square law of universal gravitation. Newtons theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets. Calculations by both John Couch Adams and Urbain Le Verrier predicted the position of the planet. A discrepancy in Mercurys orbit pointed out flaws in Newtons theory, the issue was resolved in 1915 by Albert Einsteins new theory of general relativity, which accounted for the small discrepancy in Mercurys orbit. The simplest way to test the equivalence principle is to drop two objects of different masses or compositions in a vacuum and see whether they hit the ground at the same time. Such experiments demonstrate that all objects fall at the rate when other forces are negligible
Gravity
–
Sir Isaac Newton, an English physicist who lived from 1642 to 1727
Gravity
Gravity
–
Two-dimensional analogy of spacetime distortion generated by the mass of an object. Matter changes the geometry of spacetime, this (curved) geometry being interpreted as gravity. White lines do not represent the curvature of space but instead represent the
coordinate system imposed on the curved spacetime, which would be
rectilinear in a flat spacetime.
Gravity
–
Ball falling freely under gravity. See text for description.
13.
Iceberg
–
An iceberg or ice mountain is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open water. It may subsequently become frozen into pack ice, as it drifts into shallower waters, it may come into contact with the seabed, a process referred to as seabed gouging by ice. Almost 91% of an iceberg is below the surface of the water, the word iceberg is a partial loan translation from Dutch ijsberg, literally meaning ice mountain, cognate to Danish isbjerg, German Eisberg, Low Saxon Iesbarg and Swedish isberg. Because the density of ice is about 920 kg/m³. The shape of the underwater portion can be difficult to judge by looking at the portion above the surface and this has led to the expression tip of the iceberg, for a problem or difficulty that is only a small manifestation of a larger problem. Icebergs generally range from 1 to 75 metres above sea level, the largest known iceberg in the North Atlantic was 168 metres above sea level, reported by the USCG icebreaker East Wind in 1958, making it the height of a 55-story building. These icebergs originate from the glaciers of western Greenland and may have a temperature of −15 to −20 °C. Icebergs are usually confined by winds and currents to move close to the coast, the largest icebergs recorded have been calved, or broken off, from the Ross Ice Shelf of Antarctica. Iceberg B-15, photographed by satellite in 2000, measured 295 by 37 kilometres and this iceberg was larger than Belgium. When a piece of ice melts, it makes a fizzing sound called Bergie Seltzer. This sound is made when the water-ice interface reaches compressed air trapped in the ice. As this happens, each bubble bursts, making a popping sound, the bubbles contain air trapped in snow layers very early in the history of the ice, that eventually got buried to a given depth and pressurized as it transformed into firn then to glacial ice. About a month later, this split into two pieces upon crashing into Joe Island in the Nares Strait next to Greenland. In June 2011, large fragments of the Petermann Ice Islands were observed off the Labrador coast, iceberg B-17B140 km2,1999, shipping alert issued December 2009. In addition to classification, icebergs can be classified on the basis of their shape. The two basic types of forms are tabular and non-tabular. Tabular icebergs have steep sides and a top, much like a plateau. This type of iceberg, also known as an ice island, can be quite large, Antarctic icebergs formed by breaking off from an ice shelf, such as the Ross Ice Shelf or Filchner-Ronne Ice Shelf, are typically tabular
Iceberg
–
An artist's impression of an iceberg viewed from the side, with the majority underwater
Iceberg
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Grotto in an iceberg, photographed during the
British Antarctic Expedition of 1911–1913, 5 Jan 1911. Photographer: Herbert Ponting, Alexander Turnbull Library
Iceberg
–
The
calving of Iceberg A-38 off
Ronne Ice Shelf
Iceberg
–
Iceberg A22A in the South
Atlantic Ocean
14.
Ice calving
–
Ice calving, also known as glacier calving or iceberg calving, is the breaking of ice chunks from the edge of a glacier. It is a form of ice ablation or ice disruption and is caused by the glacier expanding. It is the release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf. The ice that breaks away can be classified as an iceberg, calving of glaciers is often accompanied by a loud cracking or booming sound before blocks of ice up to 60 metres high break loose and crash into the water. The entry of the ice into the water causes large, the waves formed in locations like Johns Hopkins Glacier can be so large that boats cannot approach closer than 3 kilometres. These events have become major tourist attractions in such as Alaska. Many glaciers terminate at oceans or freshwater lakes which results naturally with the calving of large numbers of icebergs, calving of Greenlands glaciers produce 12,000 to 15,000 icebergs each year alone. Calving of ice shelves is usually preceded by a rift and these events are not often observed. Etymologically, calving is cognatic with calving as in bearing a calf and it is useful to classify causes of calving into first, second, and third order processes. First order processes are responsible for the rate of calving at the glacier scale. The first order cause of calving is longitudinal stretching, which controls the formation of crevasses, when crevasses penetrate the full thickness of the ice, calving will occur. Longitudinal stretching is controlled by friction at the base and edges of the glacier, glacier geometry and these factors, therefore, exert the primary control on calving rate. Second and third order calving processes can be considered to be superimposed on the first order process above, melting at the waterline is an important second order calving process as it undercuts the subaerial ice, leading to collapse. Other second order processes include tidal and seismic events, buoyant forces, when calving occurs due to waterline melting, only the subaerial part of the glacier will calve, leaving a submerged foot. Thus, a third order process is defined, whereby upward buoyant forces cause this ice foot to break off and this process is extremely dangerous, as it has been known to occur, without warning, up to 300m from the glacier terminus. Though many factors contribute to calving have been identified, a reliable predictive mathematical formula is still under development. Data is currently being assembled from ice shelves in Antarctica and Greenland to help establish a calving law, there are currently several concepts upon which to base a predictive law. Another theory, based on research, shows that the calving rate increases as a power of the spreading rate near the calving front
Ice calving
–
A calving glacier and the resulting ice field.
Ice calving
–
Landsat image of
Jakobshavn Isbræ. The lines show the position of the calving front of the Jakobshavn Isbræ since 1851. The date of this image is 2001 and the calving front of the glacier can be seen at the 2001 line. The area stretching from the calving front to the sea (towards the bottom left corner) is the
Ilulissat icefjord. Courtesy of
NASA Space Observatory
Ice calving
–
Glacier Bay, glacier calving
15.
Ross Ice Shelf
–
The Ross Ice Shelf is the largest ice shelf of Antarctica. It is several hundred metres thick, the nearly vertical ice front to the open sea is more than 600 kilometres long, and between 15 and 50 metres high above the water surface. Ninety percent of the ice, however, is below the water surface. Most of Ross Ice Shelf is in the Ross Dependency claimed by New Zealand and it floats in, and covers, a large southern portion of the Ross Sea and the entire Roosevelt Island located in the west of the Ross Sea. The ice shelf is named after Captain Sir James Clark Ross and it was originally called The Barrier, with various adjectives including Great Ice Barrier, as it prevented sailing further south. Ross mapped the ice front eastward to 160°W, in 1947, the US Board on Geographic Names applied the name Ross Shelf Ice to this feature and published it in the original US Antarctic Gazetteer. In January 1953 the name was changed to Ross Ice Shelf, four days later, they found their way into open water and were hoping that they would have a clear passage to their destination. But on 11 January, the men were faced with a mass of ice. Sir James Clark Ross, who was the commander, remarked, Well. Two volcanoes in the region were named by Ross for his vessels, for early Antarctic explorers seeking to reach the South Pole, the Ross Ice Shelf became a starting area. The findings were presented at a lecture entitled Universitas Antarctica, given 7 June 1911 and were published in the account of Scotts second expedition. Both Roald Amundsen and Scott crossed the shelf to reach the Pole in 1911, Amundsen wrote, Along its outer edge the Barrier shows an even, flat surface, but here, inside the bay, the conditions were entirely different. Even from the deck of the Fram we were able to observe great disturbances of the surface in every direction, the greatest elevation lay to the south in the form of a lofty, arched ridge, which we took to be about 500 feet high on the horizon. But it might be assumed that this continued to rise beyond the range of vision. The next day, the party made its first steps on the Barrier, after half an hour’s march we were already at the first important point—the connection between the sea-ice and the Barrier. This connection had always haunted our brains, a high, perpendicular face of ice, up which we should have to haul our things laboriously with the help of tackles. Or a great and dangerous fissure, which we should not be able to cross without going a long way round and we naturally expected something of the sort. This mighty and terrible monster would, of course, offer resistance in form or other
Ross Ice Shelf
–
Crevasse, Ross Ice Shelf in 2001.
Ross Ice Shelf
–
Map of Antarctica with the Ross ice shelf marked with a red X.
Ross Ice Shelf
–
"The mystic Barrier" at
Bay of Whales, near where
Amundsen first encountered it Note humans for size comparison (dark spots next to the large chunk of
sea ice at left image border)
16.
Filchner-Ronne Ice Shelf
–
The Filchner-Ronne Ice Shelf, also known as Ronne-Filchner Ice Shelf, is an Antarctic ice shelf bordering the Weddell Sea. The seaward side of the Filchner-Ronne ice shelf is divided into Eastern 79°00′S 40°00′W, the whole ice shelf covers some 430,000 km², making it the second largest ice shelf in Antarctica, after the Ross Ice Shelf. It grows perpetually due to a flow of ice sheets. From time to time, when the stresses exceed the strength of the ice, cracks form and large parts of the ice sheet separate from the ice shelf. The Ronne ice shelf is the larger and western part of the Filchner-Ronne ice shelf and it is bounded on the west by the base of the Antarctic Peninsula and Ellsworth Land. He named it the Lassiter Shelf Ice and gave the name Edith Ronne Land to the presumed to lie south of it. The shelf is named for Edith Ronne, the wife of Finn Ronne. The Filchner ice shelf is the part of the Filchner-Ronne ice shelf. It is bounded on the west by Berkner Island and on the east by Coats Land, the east part of this shelf was discovered in January–February 1912 by the German Antarctic Expedition under Wilhelm Filchner. Filchner named the feature for Kaiser Wilhelm, but the Emperor requested it be named for its discoverer, the shelf is nourished primarily by the Slessor Glacier, the Recovery Glacier, and the Support Force Glacier, all located east of Berkner Island. In October 1998, the iceberg A-38 broke off the Filchner-Ronne ice shelf and it had a size of roughly 150 by 50 km and was thus larger than Delaware. It later broke up into three parts, a large group of small icebergs, were seen off the southeast coast of the island, with one of them drifting close enough to shore to be visible from the hills above the city of Dunedin. If these were indeed the remnants of this calving, then over the course of five and a half years they had travelled north and also east around over half the globe. From January 12 and January 13,2010, an area of sea ice larger than the state of Rhode Island broke away from the Ronne-Filchner Ice Shelf, the Moderate-Resolution Imaging Spectroradiometer on NASA’s Aqua and Terra satellites captured this event in this series of photo-like images. The ice of the Filchner-Ronne ice shelf can be as thick as 600 m, the international Filchner-Ronne Ice Shelf Programme was initiated in 1973 to study the ice shelf.4 mm of rise of sea level each year. Belgrano I Base Ellsworth Station Weddell Gyre Satellite image/map of Ronne, national Snow and Ice Data Center. National Snow and Ice Data Center, big Antarctic ice sheet appears doomed, Warming climate predicted to trigger collapse of Filchner-Ronne shelf by 2100 June 2nd,2012, Vol.181 #11 Science News. This article incorporates public domain material from the United States Geological Survey document Filchner Ice Shelf
Filchner-Ronne Ice Shelf
–
The
calving of A-38 off Ronne ice shelf.
Filchner-Ronne Ice Shelf
–
Some named Antarctic iceshelves.
17.
Subglacial lake
–
A subglacial lake is a lake under a glacier, typically an ice cap or ice sheet. There are many lakes, with Lake Vostok in Antarctica being by far the largest known at present. The water below the ice remains liquid since geothermal heating balances the loss at the ice surface. The pressure causes the point of water to be below 0°C. The ceiling of the lake will be at the level where the pressure melting point of water intersects the temperature gradient. In Lake Vostok the ice over the lake is much thicker than the ice sheet around it. The water in the lake can have a level much above the level of the ground threshold. In fact, theoretically a sub-glacial lake can even exist on the top of a hill, the floating level can be thought of as the water level in a hole drilled through the ice into the lake. It is equivalent to the level at which a piece of the ice over it would if it were a normal ice shelf. The ceiling can therefore be conceived as an ice shelf that is grounded along its entire perimeter, as it moves over the lake, it enters the lake at the floating line, and it leaves the lake at the grounding line. For the lake to exist there must be a hydrostatic seal along the entire perimeter, a hydrostatic seal is created when the ice is so much higher around the lake that the equipotential surface dips down into impermeable ground. Water from underneath this ice rim is then pressed back into the lake by the hydrostatic seal, the ice surface is ten times more important than the bed surface in creating the hydrostatic seal. This means that a 1 m rise in the ice surface at the ice rim is as efficient as a 10 m rise in the bed level below it. In Lake Vostok the ice rim has been estimated to a mere 7 m, if the hydrostatic seal is penetrated when the floating level is high, the water will start flowing out in a jökulhlaup. Due to melting of the channel the discharge increases exponentially, unless other processes allow the discharge to increase even faster, due to the high head that can be achieved in subglacial lakes, jökulhlaups may reach very high rates of discharge. Russian scientist Peter Kropotkin first proposed the idea of water under Antarctic ice sheets at the end of the 19th century. Kropotkins theory was developed by Russian glaciologist I. A Zotikov. Andrey Kapitsa used seismic soundings in the region of Vostok Station made during the Soviet Antarctic Expeditions in 1959 and 1964 to measure the thickness of the ice sheet
Subglacial lake
–
NASA
MODIS image of two subglacial lakes in Antarctica.
Subglacial lake
–
Russian scientist and anarcho-communist
Peter Kropotkin first proposed the idea of fresh water under Antarctic ice.
Subglacial lake
–
Satellite image of
Lake Vostok by
NASA
18.
Lake Vostok
–
Lake Vostok is the largest of Antarcticas almost 400 known subglacial lakes. Lake Vostok is located at the southern Pole of Cold, beneath Russias Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at 3,488 m above mean sea level. The surface of fresh water lake is approximately 4,000 m under the surface of the ice. Measuring 250 km long by 50 km wide at its widest point, and covering an area of 12,500 km2, the lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m, compared to roughly 400 m deep in the basin and 800 m deep in the southern. The lake is named after Vostok Station, which in turn is named after the Vostok, a sloop-of-war ship, which means East in Russian. The continued research by Russian and British scientists led by 1993 to the confirmation of the existence of the lake by J. P. Ridley using ERS-1 laser altimetry. The overlying ice provides a continuous record of 400,000 years. On 5 February 2012, a team of Russian scientists completed the longest ever ice core of 3,768 m, the first core of freshly frozen lake ice was obtained on 10 January 2013 at a depth of 3,406 m. However, as soon as the ice was pierced, water from the underlying lake gushed up the borehole, mixing it with the Freon, a new borehole was drilled and an allegedly pristine water sample was obtained in January 2015. The Russian team plans to lower a probe into the lake to collect water samples. It is hypothesized that unusual forms of life could be found in the liquid layer. Russian scientist Peter Kropotkin first proposed the idea of water under Antarctic ice sheets at the end of the 19th century. Kropotkins theory was developed by Russian glaciologist I. A. Zotikov. Russian geographer Andrey Kapitsa used seismic soundings in the region of Vostok Station made during the Soviet Antarctic Expedition in 1959 and 1964 to measure the thickness of the ice sheet. Kapitsa was the first to suggest the existence of a lake in the region. The data from ERS-1 confirmed the findings from the 1973 British surveys, space-based radar revealed that this subglacial body of fresh water is one of the largest lakes in the world, and one of some 140 subglacial lakes in Antarctica. Russian and British scientists delineated the lake in 1996 by integrating a variety of data, including airborne ice-penetrating radar imaging observations and it has been confirmed that the lake contains large amounts of liquid water under the more than 3-kilometer-thick ice cap
Lake Vostok
–
Radar satellite image of Lake Vostok
Lake Vostok
–
Location of Lake Vostok in
East Antarctica
Lake Vostok
–
Vostok Station
Lake Vostok
–
Ice cores drilled at Vostok Station (c. 2005), which is seen in the background
19.
Ellesmere Island
–
Ellesmere Island is part of the Qikiqtaaluk Region of the Canadian territory of Nunavut. Lying within the Canadian Arctic Archipelago, it is considered part of the Queen Elizabeth Islands and it comprises an area of 196,235 km2 and the total length of the island is 830 kilometres, making it the worlds tenth largest island and Canadas third largest island. The Arctic Cordillera mountain system covers much of Ellesmere Island, making it the most mountainous in the Canadian Arctic Archipelago, the Arctic willow is the only woody species to grow on Ellesmere Island. The first human inhabitants of Ellesmere Island were small bands drawn to the area for Peary caribou, muskox, vikings from the Greenland colonies reached Ellesmere Island, Skraeling Island, and Ruin Island during hunting expeditions and trading with the Inuit groups. Unusual structures on Bache peninsula may be the remains of a late-period Dorset stone longhouse, the first European to sight the island after the height of the Little Ice Age was William Baffin in 1616. Ellesmere Island was named in 1852 by Edward Inglefields expedition after Francis Egerton, the US expedition led by Adolphus Greely in 1881 crossed the island from east to west, establishing Fort Conger in the northern part of the island. The Greely expedition found fossil forests on Ellesmere Island in the late 1880s, Stenkul Fiord was first explored in 1902 by Per Schei, a member of Otto Sverdrups 2nd Norwegian Polar Expedition. In 1906 Robert Peary led an expedition in northern Ellesmere Island, during Pearys expedition, the Ice Shelf was continuous, a modern estimate is that it covered 8,900 km2. In 2011, Jon Turk and Erik Boomer completed the first known circumnavigation of Ellesmere Island, Ellesmere Island contains Canadas northernmost point, Cape Columbia at 83°6′41″N. Barbeau Peak, the highest mountain in Nunavut is located in the British Empire Range on Ellesmere Island, the most northern mountain range in the world, the Challenger Mountains, is located in the northeast region of the island. The northern lobe of the island is called Grant Land, in July 2007, a study noted the disappearance of habitat for waterfowl, invertebrates, and algae on Ellesmere Island. The researchers noted that In the 1980s they often needed to wear hip waders to make their way to the ponds. while by 2006 the same areas were dry enough to burn. The northwest coast of Ellesmere Island was covered by a massive,500 km long ice shelf until the 20th century. A1986 survey of Canadian ice shelves found that 48 km2 or 3.3 km3 of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. The Ward Hunt Ice Shelf, the largest remaining section of thick landfast sea ice along the coastline of Ellesmere Island. It further decreased by 27% in thickness between 1967 and 1999, Schei and later Nathorst described the Paleocene-Eocene fossil forest in the Stenkul Fiord sediments. The Stenkul Fiord site represents a series of deltaic swamp and floodplain forests, the trees stood for at least 400 years. Individual stumps and stems of >1 m diameter were abundant, and are identified as Metasequoia, well preserved Pliocene peats containing abundant vertebrate and plant macrofossils characteristic of a boreal forest have been reported from Strathcona Fiord
Ellesmere Island
–
Tundra in
Quttinirpaaq National Park
Ellesmere Island
–
Satellite image montage showing Ellesmere Island and its neighbours
Ellesmere Island
–
The
Osborn Range of the
Arctic Cordillera mountain system
20.
Alfred Ernest Ice Shelf
–
The Alfred Ernest Ice Shelf is an ice shelf on the north-west part of Ellesmere Island, Canada. This ice mass is one of four remaining ice shelves on the island and this ice shelf lies between Alert Point and Cape Woods on the Wootton Peninsula. The Alfred Ernest Ice Shelf is regarded as an ice shelf that is composed of an inner unit of glacial origin. Some time around 1955, a section of the ice broke off. It is now called the ARLIS-II ice island, Glaciers of North America - Canada, Satellite Image Atlas of Glaciers of the World, U. S. G. S. Professional Paper 1386 – J –1, pg J111 – J143 Carsten Braun, Douglas R. Hardy, and Raymond S. Bradley, Journal of Geophysical Research, Vol 109
Alfred Ernest Ice Shelf
–
Satellite image showing of Alfred Ernest Ice Shelf
Alfred Ernest Ice Shelf
–
Map of part of Ellesmere Island showing location of Alfred Ernest Ice Shelf
21.
Ayles Ice Shelf
–
The Ayles Ice Shelf was one of six major ice shelves in Canada, all on the north coast of Ellesmere Island, Nunavut. The ice shelf broke off from the coast on August 13,2005, forming a giant ice island 37 metres thick, the oldest ice in the ice shelf is believed to be over 3,000 years old. The ice shelf was at, approximately 800 km south of the North Pole. The Ayles Ice Shelf, like the nearby Mount Ayles, was named for the Arctic explorer Adam Ayles, a 1986 survey of Canadian ice shelves found that 48 square km of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. On August 13,2005, the entire shelf broke clear from the coast of Ellesmere and it is believed to be the largest shelf breakup of its kind in Canada in over 30 years. The event was registered on seismometers in northern Canada, and it was also verified via satellite imagery, the event, which some have linked to global warming, is similar to the 2002 breakup of the Larsen B Ice Shelf in Antarctica. The speed of the breakup is also remarkable, it took less than an hour, Canada has lost approximately 90% of its ice shelves in the last hundred years. Within days of the breakup, the shelf had drifted over 50 km from Ellesmere Island before freezing into the sea ice for the winter. It was estimated in May,2007 to be between 138 feet and 148 feet thick, on average, in August 2007, however, the island became wedged into the Sverdrup Inlet of the Queen Elizabeth Islands. Although scientists initially thought it was likely to remain there for some time, possibly permanently, there is concern that the ice islands may become a hazard for ships and oil platforms. On August 14,1946, a U. S. Air Force patrol plane flying 300 miles north of Port Barrow, Alaska spotted an ice island, dubbed T-1, which was 15 miles wide and 18 miles across. It was estimated to be from 240 to 1,600 feet thick, over the following three years, it travelled around 1,500 miles along the Beaufort Eddy, a slow-moving ocean current that flows eastward across the North Pole, then back west along the coast. In 1950, the U. S. Air Force 58th Reconnaissance Squadron was ordered to find T-1, in July,1950, T-2 was found, a roughly rectangular ice island estimated to be 20 miles by 20 miles by dimension. In 1947, a joint U. S. -Canadian expedition had noted and photographed a fresh water sea formation in the sea off Ellesmere Island, from a photographic examination of its ridges, T-2 was discovered to be the same ice island spotted off Ellesmere Island in 1947. Later in July 1950, the U. S. Air Force found T-3, an island, nine by four. This was later occupied for brief periods in the early and mid-1950s, in August 1951, T-1 was relocated, nestled along the coast of Ellesmere Island. It is not known how long prior T-1, T-2, and T-3 had been formed, there are an estimated 80 ice islands in Canadas High Arctic, most of them part of the pack ice that covers the region. Between August 1961 and April 1962, almost 600 square kilometres of ice broke away from the Ward Hunt Ice Shelf and this event was attributed to tidal and seismic events
Ayles Ice Shelf
–
Before: Ellesmere Island on July 12, 2002.
Ayles Ice Shelf
–
After: A
NASA satellite image taken 13 August 2005 shows the collapse. The newly formed ice island forms only a small part of this picture, being the fragment very close to shore at the centre of the image. The island is ringed in the picture shown in this CBC article.
22.
List of Antarctic ice shelves
–
This is a list of Antarctic ice shelves. Ice shelves are attached to 44% of the Antarctic coastline and their total area is 1,541,700 km². Names are also listed in the Scientific Committee on Antarctic Research, the ice shelf areas are listed below, clockwise, starting in the west of East Antarctica, † Indicates that the ice shelf has collapsed. List of glaciers in the Antarctic List of Antarctic ice streams Retreat of glaciers since 1850
List of Antarctic ice shelves
–
Edge of
Ekstrom Ice Shelf
List of Antarctic ice shelves
–
Ross (472,960 km²)
23.
Severnaya Zemlya
–
Severnaya Zemlya is a 37, 000-square-kilometre archipelago in the Russian high Arctic. It lies off Siberias Taymyr Peninsula, separated from the mainland by the Vilkitsky Strait and this archipelago separates two marginal seas of the Arctic Ocean, the Kara Sea in the west and the Laptev Sea in the east. The largest glacier in the Russian Federation, the Academy of Sciences Glacier, is located in Severnaya Zemlya, Severnaya Zemlya was first noted in 1913 and first charted in 1930–32, making it the last sizeable archipelago on Earth to be explored. Administratively, the islands part of Russias Krasnoyarsk Krai federal subject. In Soviet times there were a number of stations in different locations. Severnaya Zemlya is notable in connection with the ongoing multi-year Arctic sea ice decline, until recently, ice joined the islands to Eurasia even at its smallest extent during the late summer melt season, blocking the Northeast Passage between the Atlantic and Pacific. By the late summer of 2012, however, the permanent ice had reached a record low extent, later in the 19th century Adolf Erik Nordenskiöld during the Vega Expedition sailed very close to this land in 1878 but did not notice it. However, Hovgaard was prevented from accomplishing his objectives after having become trapped in thick ice, the archipelago was not put on the map until the 1913–1915 Arctic Ocean Hydrographic Expedition of icebreakers Taimyr and Vaigach. The chief organiser and first captain of the Vaygach was officer Aleksandr Vasiliyevich Kolchak of the Imperial Russian Navy, the expedition was privately financed and was launched in 1910, being led by Boris Vilkitsky on behalf of the Russian Hydrographic Service. On 3 September 1913, members of Vilkitskys expedition landed on what is now known as Cape Berg on October Revolution Island and they raised the Russian flag on the shore and named the new territory Tayvay Land, after the first syllable of their icebreakers names. During the days that followed Vilkitskys expedition charted parts of the Laptev Sea coast of what they believed to be a single island. Barely six months later in early 1914, by order of the Secretary of the Imperial Navy, in 1926 the Presidium of the Central Executive Committee of the USSR renamed the still not fully explored land Severnaya Zemlya. On 15 May 1928 the islands were overflown by Umberto Nobile and his crew in the Airship Italia, Ushakov and his team established a small base at Golomyanny —the western end of Sredniy Island, off October Revolution Islands western coast. From there they made multiple trips into the interior and the coastlines of the larger islands. The first detailed map drawn by the expeditions cartographers showed Severnaya Zemlya to be divided into four main islands, geographic features of the territory were named after communist organisations, events and personalities. g. Cape Unslicht becoming Mys Peschanyy and Proliv Yungshturm Yuny Strait, during the Cold War era the islands of Severnaya Zemlya continued to be studied by a team of geologists from NIIGA in St. Petersburg between 1948 and 1954 under B. Egiazarov who compiled a geological map. Also more accurate maps were drawn by means of data gathered from aerial photography surveys
Severnaya Zemlya
–
Satellite image of Severnaya Zemlya, courtesy
NASA
Severnaya Zemlya
–
Severnaya Zemlya, Russia
Severnaya Zemlya
–
The
purple saxifrage (Saxifraga oppositifolia), a common plant in the high
Arctic, also occurs on Severnaya Zemlya.
Severnaya Zemlya
–
Severnaya Zemlya is the easternmost point in the breeding range of the
little auk (Alle alle).
24.
October Revolution Island
–
October Revolution Island is the largest island of the Severnaya Zemlya group in the Russian Arctic. The area of this island has been estimated at 14,170 km2 making it the 56th largest island in the world and it rises to a height of 965 m on Mount Karpinsky. Half the island is covered with glaciers reaching down into the sea, in the sections free from ice, the vegetation is desert or tundra. October Revolution Island houses five domed ice caps, clockwise from north, they are named, Rusanov, Karpinsky, University, Vavilov and Albanov. The Rusanov and Karpinsky ice caps, located on the side of the island, feed with glaciers the Matusevich Fjord of the Laptev Sea. The Karpinsky ice cap reaches a height of 963 m. Other minor ice caps on the island include the Malyutka Glacier, the coast of the island is uneven with rugged coves and headlands. The largest bays of the island are along the northern coast, both straits connect the Kara Sea in the west with the Laptev Sea in the east. Cape October is located in the part of the island facing the Red Army Strait. The Vavilov Meteorological Station was operated from 1974 to 1988 on the part of the Vavilov Ice Cap. Arctic Ocean Hydrographic Expedition List of islands of Russia List of glaciers of Russia Media related to October Revolution Island at Wikimedia Commons
October Revolution Island
–
October Revolution Island, Russia
25.
Sea level rise
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Sea level rise refers to an increase in the volume of water in the world’s oceans, resulting in an increase in global mean sea level. Sea level rise is attributed to global climate change by thermal expansion of the water in the oceans and by melting of Ice sheets. Melting of floating ice shelves or icebergs at sea raises sea levels only slightly, Sea level rise at specific locations may be more or less than the global average. Local factors might include tectonic effects, subsidence of the land, tides, currents, storms, Sea level rise is expected to continue for centuries. IPCC Summary for Policymakers, AR5,2014, indicated that the mean sea level rise will continue during the 21st century, very likely at a faster rate than observed from 1971 to 2010. A January 2017 NOAA report suggests a range of GMSL rise of 0.3 –2.5 m possible during the 21st century, Sea level rises can considerably influence human populations in coastal and island regions and natural environments like marine ecosystems. On the timescale of centuries to millennia, the melting of ice sheets could result in even higher sea level rise, partial deglaciation of the Greenland ice sheet, and possibly the West Antarctic ice sheet, could contribute 4 to 6 m or more to sea level rise. Various factors affect the volume or mass of the ocean, leading to changes in eustatic sea level. The two primary influences are temperature, and the mass of water locked up on land and sea as water in rivers, lakes, glaciers. Over much longer timescales, changes in the shape of oceanic basins. Since the Last Glacial Maximum about 20,000 years ago, sea level has risen by more than 125 m, with rates varying from tenths of a mm/yr to 10+mm/year, as a result of melting of major ice sheets. During the rest of the early Holocene, the rate of sea level rise varied from a low of about 6.0 -9.9 mm/yr to as high as 30 -60 mm/yr during brief periods of accelerated sea level rise. In sharp contrast, the period between 14,300 and 11,100 calendar years ago, which includes the Younger Dryas interval, was an interval of reduced sea level rise at about 6.0 -9.9 mm/yr. Meltwater pulse 1C was centered at 8,000 calendar years, such rapid rates of sea level rising during meltwater events clearly implicate major ice-loss events related to ice sheet collapse. The primary source may have been meltwater from the Antarctic ice sheet, other studies suggest a Northern Hemisphere source for the meltwater in the Laurentide ice sheet. For example, this research included studies of Roman wells in Caesarea and these methods in combination suggest a mean eustatic component of 0.07 mm/yr for the last 2000 years. Since 1880, as the Industrial Revolution took center stage, the ocean began to rise briskly, climbing a total of 210 mm through 2009 causing extensive erosion worldwide, Sea level rose by 6 cm during the 19th century and 19 cm in the 20th century. Evidence for this includes geological observations, the longest instrumental records, for example, geological observations indicate that during the last 2,000 years, sea level change was small, with an average rate of only 0. 0–0.2 mm per year
Sea level rise
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Map of the Earth with a six-meter sea level rise represented in red.
Sea level rise
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Trends in global average absolute sea level, 1880–2013.
Sea level rise
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Close-up of
Ross Ice Shelf, the largest ice shelf of Antarctica, about the size of France and up to several hundred metres thick.
Sea level rise
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Greenland 2007 melt anomaly, measured as the difference between the number of days on which melting occurred in 2007 compared to the average annual melting days from 1988–2006
26.
Larsen Ice Shelf
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It is named for Captain Carl Anton Larsen, the master of the Norwegian whaling vessel Jason, who sailed along the ice front as far as 68°10 South during December 1893. In finer detail, the Larsen Ice Shelf is a series of shelves that occupy distinct embayments along the coast, from north to south, the segments are called Larsen A, Larsen B, and Larsen C by researchers who work in the area. Further south, Larsen D and the much smaller Larsen E, F and G are also named, the breakup of the ice shelf since the mid 1990s has been widely reported, with the collapse of Larsen B in 2002 being particularly dramatic. The collapse of Larsen B has revealed a thriving chemotrophic ecosystem 800 m below the sea, U. S. Antarctic Program scientists were in the north-western Weddell Sea investigating the sediment record in a deep glacial trough twice the size of Texas. Methane and hydrogen sulfide associated with cold seeps is suspected as the source of the chemical energy powering the ecosystem. The area had been protected by the ice sheet from debris. The clams were observed clustered about the vents, the former Larsen B, by contrast, had been stable for at least 10,000 years. The ice of the shelf is renewed on a much shorter time-scale, the speed of Crane Glacier increased threefold after the collapse of the Larsen B and this is likely to be due to the removal of a buttressing effect of the ice shelf. Data collected in 2007 by a team of investigators through satellite-based radar measurements suggests that the overall ice-sheet mass balance in Antarctica is increasingly negative. The Larsen disintegration events were unusual by past standards, typically, ice shelves lose mass by iceberg calving and by melting at their upper and lower surfaces. The disintegration events were linked by The Independent newspaper in 2005 to ongoing climate warming in the Antarctic Peninsula, according to a paper published in Journal of Climate in 2006, the peninsula at Faraday station warmed by 2. The Larsen A ice shelf disintegrated in January 1995, during 31 January 2002 to March 2002 the Larsen B sector partially collapsed and parts broke up,3,250 km2 of ice 220 m thick, covering an area comparable to the US state of Rhode Island. In 2015 a study concluded that the remaining Larsen B ice-shelf will disintegrate by the end of the decade, based on observations of faster flow and rapid thinning of glaciers in the area. Larsen B was stable for at least 10,000 years, essentially the entire Holocene period since the last glacial period, by contrast, Larsen A was absent for a significant part of that period and reformed beginning about 4,000 years ago, according to the study. Despite its great age, the Larsen B was clearly in trouble at the time of the collapse, with warm currents eating away the underside of the shelf, it had become a hotspot of global warming. What especially surprised glaciologists was the speed of the breakup, which was a three weeks. Andrew Fleming said to Reuters, The Larsen B shattered like car safety glass into thousands and thousands of pieces and it disappeared in the space of about a week. Larsen C is the fourth largest ice shelf in Antarctica, with an area of about 50,000 km2, in 2004, a report concluded that although the remaining Larsen C region appeared to be relatively stable, continued warming could lead to its breakup within the next decade
Larsen Ice Shelf
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The collapse of Larsen B, showing the diminishing extent of the shelf from 1998 to 2002.
Larsen Ice Shelf
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Some Antarctic iceshelves.
Larsen Ice Shelf
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Clear view of the
Antarctic Peninsula, the Larsen Ice Shelf, and the
sea ice covered waters around the region.
Larsen Ice Shelf
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Larsen B area in March 2013
27.
Global warming
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Global warming and climate change are terms for the observed century-scale rise in the average temperature of the Earths climate system and its related effects. Multiple lines of evidence show that the climate system is warming. The largest human influence has been emission of gases such as carbon dioxide, methane. These findings have been recognized by the science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Future climate change and associated impacts will differ from region to region around the globe, anticipated effects include warming global temperature, rising sea levels, changing precipitation, and expansion of deserts in the subtropics. Warming is expected to be greater over land than over the oceans and greatest in the Arctic, with the retreat of glaciers, permafrost. Effects significant to humans include the threat to security from decreasing crop yields. Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to its effects, most countries are parties to the United Nations Framework Convention on Climate Change, whose ultimate objective is to prevent dangerous anthropogenic climate change. Public reactions to global warming and concern about its effects are also increasing, a global 2015 Pew Research Center report showed a median of 54% consider it a very serious problem. There are significant regional differences, with Americans and Chinese among the least concerned, the global average surface temperature shows a warming of 0.85 °C in the period 1880 to 2012, based on multiple independently produced datasets. Earths average surface temperature rose by 0. 74±0.18 °C over the period 1906–2005, the rate of warming almost doubled for the last half of that period. The rest has melted ice and warmed the continents and atmosphere, the average temperature of the lower troposphere has increased between 0.12 and 0.135 °C per decade since 1979, according to satellite temperature measurements. The warming that is evident in the temperature record is consistent with a wide range of observations. The probability that these changes could have occurred by chance is virtually zero, temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures, ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation. Since the beginning of industrialisation the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years, the thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Some of this warming will be driven by past natural forcings which are still seeking equilibrium in the climate system
Global warming
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Atmospheric CO 2 concentration from 650,000 years ago to near present, using ice core proxy data and direct measurements.
Global warming
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Global mean surface temperature change from 1880 to 2014, relative to the 1951–1980 mean. The black line is the annual mean and the red line is the 5-year
running mean. The green bars show uncertainty estimates. Source: NASA GISS.
Global warming
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Ship tracks can be seen as lines in these clouds over the Atlantic Ocean on the east coast of the United States. Atmospheric particles from these and other sources could have a large effect on climate through the aerosol indirect effect.
Global warming
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Sea ice, shown here in
Nunavut, in northern Canada, reflects more sunshine, while open ocean absorbs more, accelerating melting.
28.
Meltwater
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Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the zone of glaciers, where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions, in a way in which the more dangerous lahars form. When meltwater pools on the rather than flowing, it forms melt ponds. As the weather gets colder meltwater will often re-freeze, Meltwater can collect or melt under the ices surface. These pools of water, known as subglacial lakes can form due to geothermal heat, Meltwater provides drinking water for a large proportion of the worlds population, as well as providing water for irrigation and hydroelectric plants. Some cities around the world have large lakes that collect snow melt to supplement water supply, cities that source water from meltwater include Melbourne, Canberra, Los Angeles, Las Vegas amongst others. Glacial meltwater comes from glaciers that have receded over time, often, there will be rivers flowing through glaciers into lakes. These brilliantly blue lakes get their color from rock flour, sediment that has been transported through the rivers to the lakes and this sediment comes from rocks grinding together underneath the glacier. The fine powder is suspended in the water and absorbs and scatters varying colors of sunlight. Meltwater also acts as a lubricant in the sliding of glaciers. Using GPS measurements to study ice flow has revealed that movement is greatest in summer when the meltwater levels are highest. Meltwater can be an indication of abrupt climate change and it can also destabilize glacial lakes leading to sudden floods, and destabilize snowpack causing avalanches. Dammed glacial meltwater from a lake that is released suddenly can result in the floods. Historically Meltwater pulse 1A was a prominent feature of the last deglaciation, extreme Ice Survey Groundwater Moulin Snowmelt Surface water June 4,2007, BBC, UN warning over global ice loss United Nations Environment Program, Global Outlook for Ice and Snow
Meltwater
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Meltwater from
Mount Edith Cavell Cavell Glacier
Meltwater
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Meltwater in early spring in
a stream in Pennsylvania
Meltwater
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Refrozen glacial meltwater from the
Canada Glacier, in Antarctica
Meltwater
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Meltwater in Skaftafellsjökull, Iceland
29.
Antarctic Bottom Water
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The Antarctic bottom water is a type of water mass in the Southern Ocean surrounding Antarctica with temperatures ranging from −0.8 to 2 °C, salinities from 34.6 to 34.7 psu. Being the densest water mass of the World Ocean, AABW is found to occupy the range below 4000 m of all ocean basins that have a connection to the Southern Ocean at that level. The major significance of Antarctic bottom water is that it is the coldest bottom water, Antarctic bottom water also has a high oxygen content relative to the rest of the oceans deep waters. This is due to the oxidation of deteriorating organic content in the rest of the deep oceans, Antarctic bottom water has thus been considered the ventilation of the deep ocean. Antarctic bottom water is created in part due to the overturning of ocean water. Antarctic bottom water is formed in the Weddell and Ross Seas, off the Adélie Coast and by Cape Darnley from surface water cooling in polynyas, a unique feature of Antarctic bottom water is the cold surface wind blowing off the Antarctic continent. The surface wind creates the polynyas which opens up the surface to more wind. This Antarctic wind is stronger during the months and thus the Antarctic bottom water formation is more pronounced during the Antarctic winter season. Surface water is enriched in salt from sea ice formation, due to its increased density, it flows down the Antarctic continental margin and continues north along the bottom. It is the densest water in the ocean, and underlies other bottom. The Weddell Sea Bottom Water is the densest component of the Antarctic bottom water, upon reaching the equator, about one-third of the northward flowing Antarctic bottom water enters the Guiana Basin, mainly through the southern half of the Equatorial Channel at 35°W. The other part recirculates and some of it flows through the Romanche Fracture Zone into the eastern Atlantic, at 44°W, north of the Ceará Rise, Antarctic bottom water flows west in the interior of the basin. A large fraction of the Antarctic bottom water enters the eastern Atlantic through the Vema Fracture Zone, in the Indian Ocean the Crozet-Kerguelen Gap allows Antarctic bottom water to move toward the equator. This northward movement amounts to 2.5 Sv and it takes the Antarctic Bottom Water 23 years to reach the Crozet-Kerguelen Gap. Glossary of Physical Oceanography Steele, John H. Steve A, “Formation of Antarctic Bottom Water in the Weddell Sea, ” Journal of Geophysical Research, Vol.76, No
Antarctic Bottom Water
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AABW is formed in the Southern Ocean from surface water cooling in polynyas
