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; this ice shelf lies between Cape Woods on the Wootton Peninsula. The Alfred Ernest Ice Shelf is regarded as a composite ice shelf, composed of an inner unit of glacial origin and a trunk glacier originating from sea ice; some time around 1955, a section of the ice shelf 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, Raymond S. Bradley, Journal of Geophysical Research, Vol 109. Surface mass balance of the Ward Hunt Ice Rise and Ward Hunt Ice Shelf, Ellesmere Island, Canada, Roy M. Koerner Earth Observatory, by: Nasa Were a Part of the Earths Enterprise Jiancheng Zheng, Akira Kudo, David A. Fisher, Erik W. Blake and M. Gerasimoff, The Holocene 8, 4 pg. 413 – 421, Solid electrical conductivity from four, Agassiz ice cores, Ellesmere Island NWT, Canada: high-resolution signal and noise over the last millennium and low resolution over the Holocene Fletcher's Ice Island
Global warming is a long-term rise in the average temperature of the Earth's climate system, an aspect of climate change shown by temperature measurements and by multiple effects of the warming. Though earlier geological periods experienced episodes of warming, the term refers to the observed and continuing increase in average air and ocean temperatures since 1900 caused by emissions of greenhouse gasses in the modern industrial economy. In the modern context the terms global warming and climate change are used interchangeably, but climate change includes both global warming and its effects, such as changes to precipitation and impacts that differ by region. Many of the observed warming changes since the 1950s are unprecedented in the instrumental temperature record, in historical and paleoclimate proxy records of climate change over thousands to millions of years. In 2013, the Intergovernmental Panel on Climate Change Fifth Assessment Report concluded, "It is likely that human influence has been the dominant cause of the observed warming since the mid-20th century."
The largest human influence has been the emission of greenhouse gases such as carbon dioxide and nitrous oxide. Climate model projections summarized in the report indicated that during the 21st century, the global surface temperature is to rise a further 0.3 to 1.7 °C to 2.6 to 4.8 °C depending on the rate of greenhouse gas emissions and on climate feedback effects. These findings have been recognized by the national science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Future climate change effects are expected to include rising sea levels, ocean acidification, regional changes in precipitation, expansion of deserts in the subtropics. Surface temperature increases are greatest in the Arctic, with the continuing retreat of glaciers and sea ice. Predicted regional precipitation effects include more frequent extreme weather events such as heat waves, wildfires, heavy rainfall with floods, heavy snowfall. Effects directly significant to humans are predicted to include the threat to food security from decreasing crop yields, the abandonment of populated areas due to rising sea levels.
Environmental impacts appear to include the extinction or relocation of ecosystems as they adapt to climate change, with coral reefs, mountain ecosystems, Arctic ecosystems most threatened. Because the climate system has a large "inertia" and greenhouse gases will remain in the atmosphere for a long time, climatic changes and their effects will continue to become more pronounced for many centuries if further increases to greenhouse gases stop. Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, possible future climate engineering. Most countries are parties to the United Nations Framework Convention on Climate Change, whose ultimate objective is to prevent dangerous anthropogenic climate change. Parties to the UNFCCC have agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 °C compared to pre-industrial levels, with efforts made to limit warming to 1.5 °C. Some scientists call into question climate adaptation feasibility, with higher emissions scenarios, or the two degree temperature target.
Public reactions to global warming and concern about its effects are increasing. A 2015 global survey showed that a median of 54% of respondents consider it "a serious problem", with significant regional differences: Americans and Chinese are among the least concerned. Multiple independently produced datasets confirm that between 1880 and 2012, the global average surface temperature increased by 0.85 °C. Since 1979 the rate of warming has doubled. Climate proxies show the temperature to have been stable over the one or two thousand years before 1850, with regionally varying fluctuations such as the Medieval Warm Period and the Little Ice Age. Although the increase of the average near-surface atmospheric temperature is used to track global warming, over 90% of the additional energy stored in the climate system over the last 50 years has accumulated in the oceans; the rest warmed the continents and the atmosphere. The warming evident in the instrumental temperature record is consistent with a wide range of observations, as documented by many independent scientific groups.
Examples include sea level rise, widespread melting of snow and land ice, increased heat content of the oceans, increased humidity, the earlier timing of spring events, e.g. the flowering of plants. Global warming refers with the amount of warming varying by region. Since 1979, global average land temperatures have increased about twice as fast as global average ocean temperatures; this is due to the larger heat capacity of the oceans and because oceans lose more heat by evaporation. Where greenhouse gas emissions occur does not impact the location of warming because the major greenhouse gases persist long enough to diffuse across the planet, although localized black carbon deposits on snow and ice do contribute to Arctic warming; the Northern Hemisphere and North Pole have heated much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, its arrangement around the Arctic Ocean has resulted in the maximum surface area flipping from reflective snow and ice cover to ocean and land surfaces that absorb more sunlight.
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface. Sea ice covers about 12 % of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds and temperature fluctuations, sea ice is 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 incorporate icebergs. Sea ice does not grow and melt. During its lifespan, it is dynamic. Due to the combined action of winds, water temperature, air temperature fluctuations, sea ice expanses undergo a significant amount of deformation.
Sea ice is classified according to whether or not it is able to drift, according to its age. 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 fast ice. Alternatively, unlike fast ice, drift ice occurs further offshore in wide areas, encompasses ice, 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 marginal ice zone and a central pack. Drift ice consists of floes, individual pieces of sea ice 20 metres or more across. There are names for various floe sizes: small – 20 to 100 m; 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, young ice, first-year and old. New ice is a general term used for frozen sea water that does not yet make up solid ice, it may consist of slush, or shuga. Other terms, such as grease ice and pancake ice, are used for ice crystal accumulations under the action of wind and waves. Nilas designates a sea ice crust up to 10 centimetres in thickness, it swells. Nilas can be further subdivided into dark nilas – up to 5 cm in thickness and dark, light nilas – over 5 cm in thickness and lighter in color. Young ice is a transition stage between nilas and first-year ice, ranges in thickness from 10 cm to 30 cm, Young ice can be further subdivided into grey ice – 10 cm to 15 cm in thickness, grey-white ice – 15 cm to 30 cm in thickness. Young ice is not as flexible as tends to break under wave action. In a compression regime, it will either ridge. First-year sea ice is ice, thicker than young ice but has no more than one year growth. In other words, it is ice that grows in the fall and winter but does not survive the spring and summer months.
The thickness of this ice ranges from 0.3 m to 2 m. First-year ice may be further divided into thin and thick. Old sea ice is sea ice. For this reason, this ice is thicker than first-year sea ice. Old ice is divided into two types: second-year ice, which has survived one melting season, multiyear ice, which has survived more than one. Multi-year ice is much more common in the Arctic; the reason for this is. In the Arctic, much of the sea ice is land-locked. While fast ice is stable, drift ice undergoes complex deformation processes that give rise to sea ice's wide variety of landscapes. Wind is thought to be the main driving force along with ocean currents; the Coriolis force and sea ice surface tilt have been invoked. These driving forces induce a state of stress within the drift ice zone. An ice floe converging toward another and pushing against it will generate a state of compression at the boundary between both; the ice cover may undergo a state of tension, resulting in divergence and fissure opening.
If two floes drift sideways past each other while remaining in contact, this will create a state of shear. Sea ice deformation results from the interaction between ice floes, as they are driven against each other; the end result may be of three types of features: 1) Rafted ice, when one piece is overriding another.
A subglacial lake is a lake under a glacier an ice cap or ice sheet. There are many such lakes, with Lake Vostok in Antarctica being by far the largest known on Earth at present; the water below the ice remains liquid since geothermal heating balances the heat loss at the ice surface. The pressure causes the melting point of water to be below 0 °C; the ceiling of the subglacial 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 thus much thicker than the ice sheet around it. Hypersaline lakes remain liquid due to their salt content; the water in the lake can have a floating level much above the level of the ground threshold. In fact, theoretically a sub-glacial lake can exist on the top of a hill, provided that the ice over it is so much thinner that it creates the required hydrostatic seal; 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 float if it were a normal ice shelf.
The ceiling can therefore be conceived as an ice shelf, grounded along its entire perimeter, which explains why it has been called a captured ice shelf. As it moves over the lake, it enters the lake at the floating line, it leaves the lake at the grounding line. For the lake to exist there must be a hydrostatic seal along the entire perimeter, if the floating level is higher than the threshold. 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 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, while the floating level is about 3 km above the lake ceiling. 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 faster. Due to the high head that can be achieved in subglacial lakes, jökulhlaups may reach high rates of discharge. Russian scientist Peter Kropotkin first proposed the idea of fresh water under Antarctic ice sheets at the end of the 19th century, he theorized that the tremendous pressure exerted by the cumulative mass of thousands of vertical meters of ice could increase the temperature at the lowest portions of the ice sheet to the point where the ice would melt. Kropotkin's theory was further developed by Russian glaciologist I. A Zotikov, who wrote his Ph. D. thesis on this subject in 1967. 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. In cooperation with other scientists, Kapitsa discovered a subglacial lake in this region named Lake Vostok, one of the most remarkable geographical discoveries of the 20th century.
Subglacial lakes in Antarctica were suggested by Oswald and Robin and subsequently confirmed theoretically by Oswald. They are identified in radio-echo sounding data as continuous and specular reflectors which dip against the ice surface at around x10 of the surface slope angle, as this is requirement for hydrostatic stability; the largest lakes are clustered in the Dome C-Vostok area of East Antarctica - due to the thick insulating ice and rugged tectonically influenced subglacial topography. The largest is Lake Vostok with other lakes notable for their size being Lake Concordia and Aurora Lake. Several lakes were delineated by the famous SPRI-NSF-TUD surveys undertaken until the mid-seventies. A compilation by Siegert et al. reported 145 subglacial lakes in Antarctica. Since this original compilation several smaller surveys has discovered many more subglacial lakes throughout Antarctica, notably by Carter et al. who identified a spectrum of subglacial lake types based on their properties in radio-echo sounding datasets.
Gray et al. interpreted ice surface slumping and raising from RADARSAT data as evidence for subglacial lakes filling and emptying - termed "active" lakes. Wingham et al. used radar altimeter data to show coincident uplift and subsidence: implying drainage between lakes. NASA's ICESat satellite was key in developing this concept further and subsequent work demonstrated the pervasiveness of this phenomenon. ICESat ceased measurements in 2007 and the detected "active" lakes were compiled by Smith et al. who identified 124 such lakes. In total around 250-300 Antarctic subglacial lakes are known; the realisation that lakes were interconnected created new contamination concerns for plans to drill into lakes. There are three projects to directly sample subglacial lakes in Antarctica; these are the British led Subglacial Lake Ellsworth project, the U. S. led the Russian led Lake Vostok program. No program has gained access but is expected during the austral summer of 2011-12; the role of subglacial lakes on ice dynamics is unclear - on the Greenland Ice Sheet subglacial water acts to enhance basal ice motion in a complex manner.
The "Recovery Lakes" lie at the head of a major ice stream and may influence the dynamics of the region. A modest speed up of Byrd Glacier may have been influenced by a subglacial drainage event (Stea
Severnaya Zemlya is a 37,000-square-kilometre archipelago in the Russian high Arctic. It lies off Siberia's Taymyr Peninsula, separated from the mainland by the Vilkitsky Strait; this archipelago separates two marginal seas of the Arctic Ocean, the Kara Sea in the west and the Laptev Sea in the east. 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 form part of Russia's Krasnoyarsk Krai federal subject. In Soviet times there were a number of research stations in different locations, but there are no human inhabitants in Severnaya Zemlya except for the Prima Polar Station near Cape Baranov; the largest glacier in the Russian Federation, the Academy of Sciences Glacier, is located in Severnaya Zemlya. The archipelago is notable as well in connection with the ongoing multiyear Arctic sea ice decline; until ice joined the islands to Eurasia at its smallest extent during the late summer melt season, blocking the Northeast Passage between the Atlantic and the Pacific.
By the late summer of 2012, the permanent ice had reached a record low extent and open water appeared to the north of the archipelago. Although located not far off the northern coast of Russia, nested among Arctic ice-locked waters, the archipelago, now known as Severnaya Zemlya was not formally recorded until the 20th century. Earlier explorers deemed that there was a land mass in the general area of the archipelago, such as in the report by Matvei Gedenschtrom and Yakov Sannikov made in 1810 at the time of their exploration of the New Siberian Islands. In the 19th century Adolf Erik Nordenskiöld during the Vega Expedition sailed close to this land in 1878 but did not notice it. In 1882, Danish Arctic explorer and naval officer Andreas Peter Hovgaard, leader of the Arctic survey Dijmphna Expedition, set himself the goal of discovering land north of Cape Chelyuskin and explore the unknown northeastern limits of the Kara Sea. However, Hovgaard was prevented from accomplishing his objectives after having become trapped in thick ice and his expedition was unable to reach the Taymyr Peninsula's shores.
At the end of the 19th century both Nansen's Fram expedition of 1895, as well Eduard Toll's Russian polar expedition of 1900–02 on ship Zarya failed to note any traces of land to the north of the 55 kilometres wide strait between the Kara Sea and the Laptev Sea that they navigated. 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 financed and was launched in 1910, being led by Boris Vilkitsky on behalf of the Russian Hydrographic Service; this venture accomplished its goal of exploring the uncharted areas of the continental side of the Northern Sea Route in what was seen as the culmination of the Great Northern Expedition, an ambitious enterprise conceived by emperor Peter I the Great in order to map the whole of the northern coast of Russia to the east. On 3 September 1913, members of Vilkitsky's expedition landed on what is now known as Cape Berg on October Revolution Island.
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 Vilkitsky's expedition charted parts of the Laptev Sea coast of what they believed to be a single island. Six months in early 1914, by order of the Secretary of the Imperial Navy, the new discovery was renamed Emperor Nicholas II Land, after ruling Emperor Nicholas II of Russia. In 1926 the Presidium of the Central Executive Committee of the USSR renamed the still not explored land Severnaya Zemlya. In May 1928, an attempt was made by Umberto Nobile and his crew in the Airship Italia to overfly the islands, but adverse weather conditions forced them to turn southward when only an hour or two from viewing the archipelago's coastline. In the spring of 1931 Georgy Ushakov, accompanied by the geologist Nikolay Urvantsev, the veteran surveyor Sergei Zhuravlev, the radio operator Vasily Khodov surveyed Severnaya Zemlya during a two-year expedition to the archipelago.
Ushakov and his team established a small base at Golomyanny – the western end of Sredniy Island, off October Revolution Island's western coast. From there they made multiple surveying trips into the interior and the coastlines of the larger islands; the first detailed map drawn by the expedition's cartographers showed Severnaya Zemlya to be divided into four main islands. Geographic features of the territory were named after communist organisations and personalities. About Severnaya Zemlya Ushakov wrote: I have seen God-forsaken Chukotka Peninsula, blizzard-ridden Wrangel Island, twice visited fog-enshrouded Novaya Zemlya, I have seen Franz Josef Land with its enamel sky and proud cliffs garbed in blue, hardened glacial streams, but nowhere did I witness such grimness or such depressing, lifeless relief... The Graf Zeppelin flew over the area during its polar flight of July 1931 and took some cartographic and meteorological data. Though German communists had endured great suffering under the Third Reich, following the anti-German sentiment caused by the 1941–1945 Great Patriotic War i
Canada is a country in the northern part of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering 9.98 million square kilometres, making it the world's second-largest country by total area. Canada's southern border with the United States is the world's longest bi-national land border, its capital is Ottawa, its three largest metropolitan areas are Toronto and Vancouver. As a whole, Canada is sparsely populated, the majority of its land area being dominated by forest and tundra, its population is urbanized, with over 80 percent of its inhabitants concentrated in large and medium-sized cities, many near the southern border. Canada's climate varies across its vast area, ranging from arctic weather in the north, to hot summers in the southern regions, with four distinct seasons. Various indigenous peoples have inhabited what is now Canada for thousands of years prior to European colonization. Beginning in the 16th century and French expeditions explored, settled, along the Atlantic coast.
As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces; this began an accretion of provinces and territories and a process of increasing autonomy from the United Kingdom. This widening autonomy was highlighted by the Statute of Westminster of 1931 and culminated in the Canada Act of 1982, which severed the vestiges of legal dependence on the British parliament. Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition, with Elizabeth II as its queen and a prime minister who serves as the chair of the federal cabinet and head of government; the country is a realm within the Commonwealth of Nations, a member of the Francophonie and bilingual at the federal level. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, education.
It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Canada's long and complex relationship with the United States has had a significant impact on its economy and culture. A developed country, Canada has the sixteenth-highest nominal per capita income globally as well as the twelfth-highest ranking in the Human Development Index, its advanced economy is the tenth-largest in the world, relying chiefly upon its abundant natural resources and well-developed international trade networks. Canada is part of several major international and intergovernmental institutions or groupings including the United Nations, the North Atlantic Treaty Organization, the G7, the Group of Ten, the G20, the North American Free Trade Agreement and the Asia-Pacific Economic Cooperation forum. While a variety of theories have been postulated for the etymological origins of Canada, the name is now accepted as coming from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement".
In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona. Cartier used the word Canada to refer not only to that particular village but to the entire area subject to Donnacona. From the 16th to the early 18th century "Canada" referred to the part of New France that lay along the Saint Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named the Canadas. Upon Confederation in 1867, Canada was adopted as the legal name for the new country at the London Conference, the word Dominion was conferred as the country's title. By the 1950s, the term Dominion of Canada was no longer used by the United Kingdom, which considered Canada a "Realm of the Commonwealth"; the government of Louis St. Laurent ended the practice of using'Dominion' in the Statutes of Canada in 1951. In 1982, the passage of the Canada Act, bringing the Constitution of Canada under Canadian control, referred only to Canada, that year the name of the national holiday was changed from Dominion Day to Canada Day.
The term Dominion was used to distinguish the federal government from the provinces, though after the Second World War the term federal had replaced dominion. Indigenous peoples in present-day Canada include the First Nations, Métis, the last being a mixed-blood people who originated in the mid-17th century when First Nations and Inuit people married European settlers; the term "Aboriginal" as a collective noun is a specific term of art used in some legal documents, including the Constitution Act 1982. The first inhabitants of North America are hypothesized to have migrated from Siberia by way of the Bering land bridge and arrived at least 14,000 years ago; the Paleo-Indian archeological sites at Old Crow Flats and Bluefish Caves are two of the oldest sites of human habitation in Canada. The characteristics of Canadian indigenous societies included permanent settlements, complex societal hierarchies, trading networks; some of these cultures had collapsed by the time European explorers arrived in the late 15th and early 16th centuries and have only been discovered through archeological investigations.
The indigenous population at the time of the first European settlements is estimated to have been between 200,000