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Grounding Line
Marine ice sheet instability (MISI) describes the potential for ice sheets grounded below sea level to destabilize in a runaway fashion. The mechanism was first proposed in the 1970s by Johannes Weertman and was quickly identified as a means by which even gradual anthropogenic warming could lead to relatively rapid sea level rise. In Antarctica, the West Antarctic Ice Sheet, the Aurora Subglacial Basin, and the Wilkes Basin are each grounded below sea level and are inherently subject to MISI. General The term ''marine ice sheet'' describes an ice sheet whose base rests on ground below sea level, and ''marine ice sheet instability'' describes the inherent precarious nature of marine ice sheets due to Archimedes' principle. Because seawater is denser than ice, marine ice sheets can only remain stable where the ice is thick enough for its mass to exceed the mass of the seawater displaced by the ice. In other words, wherever ice exists below sea level, it is held in place only by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Antarctic Collapse
West or Occident is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sun sets on the Earth. Etymology The word "west" is a Germanic word passed into some Romance languages (''ouest'' in French, ''oest'' in Catalan, ''ovest'' in Italian, ''oeste'' in Spanish and Portuguese). As in other languages, the word formation stems from the fact that west is the direction of the setting sun in the evening: 'west' derives from the Indo-European root ''*wes'' reduced from ''*wes-pero'' 'evening, night', cognate with Ancient Greek ἕσπερος hesperos 'evening; evening star; western' and Latin vesper 'evening; west'. Examples of the same formation in other languages include Latin occidens 'west' from occidō 'to go down, to set' and Hebrew מַעֲרָב maarav 'west' from עֶרֶב erev 'evening'. Navigation To go west using a compass for navigation (in a place where magnetic north is the same dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydro-fracturing (Ice Sheet)
Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. As of 2012, 2.5 million "frac jobs" had been performed worldwide on oil and gas wells, over one million of those within the U.S. Such treatment is generally necessary to achieve adequate flow rates in shale gas, tight gas, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciology
Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on people includes the fields of human geography and anthropology. The discoveries of water ice on the Moon, Mars, Europa and Pluto add an extraterrestrial component to the field, which is referred to as "astroglaciology". Overview A glacier is an extended mass of ice formed from snow falling and accumulating over a long period of time; glaciers move very slowly, either descending from high mountains, as in valley glaciers, or moving outward from centers of accumulation, as in continental glaciers. Areas of study within glaciology include glacial history and the reconstruction of past glaciation. A glaciologist is a person who studies glaciers. A glacial geologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Sheets
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America. 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 flows 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 ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seabed Gouging By Ice
Seabed gouging by ice is a process that occurs when floating ice features (typically icebergs and Pressure ridge (ice), sea ice ridges) drift into shallower areas and their keel comes into contact with the seabed.King 2011Palmer & Been 2011Barrette 2011 As they keep drifting, they produce long, narrow furrows most often called ''gouges'', or ''scours''.Wadhams 2000, p. 72Weeks 2010, Ch. 13 This phenomenon is common in offshore environments where ice is known to exist. Although it also occurs in rivers and lakes,Noble and Comfort 1982Grass 1984 it appears to be better documented from oceans and sea expanses.Palmer & Been 2011Wadhams 2000, p. 72Weeks 2010, Ch. 13 Seabed scours produced via this mechanism should not be confused with Strudel (ice)#Strudel scours, strudel scours. These result from spring run-off water flowing onto the surface of a given sea ice expanse, which eventually drains away through cracks, seal breathing holes, etc. The resulting turbulence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Sheet Dynamics
Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and the strength of their bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with longer periods of inactivity, on both hourly and centennial time scales. Ice-sheet dynamics are of interest in modelling future sea level rise. General Boundary conditions The interface between an ice stream and the ocean is a significant control of the rate of flow. Ice shelves are thick layers of ice floating on the sea – can stabilise the glaciers that feed them. These tend to have accumulation on their tops, may experience melting on their bases, and calve icebergs at their periphery. The catastrophic collapse of the Larsen B ice shelf in the space of three weeks during Febr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Totten Glacier
Totten Glacier is a large glacier draining a major portion of the East Antarctic Ice Sheet, through the Budd Coast of Wilkes Land in the Australian Antarctic Territory. The catchment drained by the glacier is estimated at , extending approximately into the interior and holds the potential to raise sea level by at least . Totten drains northeastward from the continental ice but turns northwestward at the coast where it terminates in a prominent tongue close east of Cape Waldron. It was first delineated from aerial photographs taken by USN Operation Highjump (1946–47), and named by Advisory Committee on Antarctic Names (US-ACAN) for George M. Totten, midshipman on of the United States Exploring Expedition (1838–42), who assisted Lieutenant Charles Wilkes with correction of the survey data obtained by the expedition. Totten Ice Shelf is a floating portion of Totten Glacier, laterally bounded by the Aurora Subglacial Basin to the south and Law Dome to the north. The ice she ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pine Island Glacier
Pine Island Glacier (PIG) is a large ice stream, and the fastest melting glacier in Antarctica, responsible for about 25% of Antarctica's ice loss. The glacier ice streams flow west-northwest along the south side of the Hudson Mountains into Pine Island Bay, Amundsen Sea, Antarctica. It was mapped by the United States Geological Survey (USGS) from surveys and United States Navy (USN) air photos, 1960–66, and named by the Advisory Committee on Antarctic Names (US-ACAN) in association with Pine Island Bay. The area drained by Pine Island Glacier comprises about 10% of the West Antarctic Ice Sheet. Satellite measurements have shown that the Pine Island Glacier Basin has a greater net contribution of ice to the sea than any other ice drainage basin in the world and this has increased due to recent acceleration of the ice stream. An iceberg about twice the size of Washington, DC broke off from the glacier in February 2020. Pine Island Glacier's ice velocity has accelerated to over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thwaites Glacier
Thwaites Glacier, nicknamed the Doomsday Glacier, is an unusually broad and vast Antarctic glacier flowing into Pine Island Bay, part of the Amundsen Sea, east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. Its surface speeds exceed per year near its grounding line. Its fastest-flowing grounded ice is centered between east of Mount Murphy. In 1967, the Advisory Committee on Antarctic Names named the glacier after Fredrik T. Thwaites (1883–1961), a glacial geologist, geomorphologist and professor emeritus at the University of Wisconsin–Madison. Thwaites Glacier is closely monitored for its potential to raise sea levels. Along with the Pine Island Glacier, it has been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, because of its apparent vulnerability to significant retreat. This hypothesis is based on both theoretical studies of the stability of marine ice sheets and observations of large changes on these two glaciers. In recent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geophysical Research Letters
''Geophysical Research Letters'' is a biweekly peer-reviewed scientific journal of geoscience published by the American Geophysical Union that was established in 1974. The editor-in-chief is Harihar Rajaram. Aims and scope The journal aims for rapid publication of concise research reports on one or more of the disciplines covered by the American Geophysical Union, such as atmospheric sciences, solid Earth, space science, oceanography, hydrology, land surface processes, and the cryosphere. The journal also publishes invited reviews that cover advances achieved during the past two or three years. The target readership is the earth science community, the broader scientific community, and the general public. Abstracting and indexing This journal is abstracted and indexed in: According to the 2020 ''Journal Citation Reports'', the journal has a 2019 impact factor of 4.58. ''Geophysical Research Letters'' was also the 5th most cited publication on climate change between 1999 and 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meltwater
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 ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ..., in a similar way in which the more dangerous lahars form. When meltwater pools on the surface rather than flowing, it forms melt ponds. As the weather gets colder meltwater will often re-freeze. Meltwater can collect or melt under the ice's surface. These pools of water, known as subglacial lakes can form due to geothermal heat and friction. Water source Meltwater provides drinking water for a large proportion of the world's population, as well as pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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