An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (20,000 mile²). "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia Square Kilometre ( US spelling square kilometer) symbol km2, is a decimal multiple of the SI unit of The square mile is an imperial and US unit of Area equal the area of a square of one statute mile. [1] The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada and North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America. Greenland (Kalaallit Nunaat meaning "Land of the Greenlanders" Grønland is a self-governing Danish Province located between the "Last glacial" redirects here For the period of maximum glacier extent during this time see Last Glacial Maximum The last glacial period The Laurentide Ice Sheet was a massive sheet of ice that covered hundreds of thousands of square miles including most of Canada and a large portion of the northern Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page "Last glacial" redirects here For the period of maximum glacier extent during this time see Last Glacial Maximum The last glacial period The Patagonian Ice Sheet was a large elongated and narrow Ice sheet that covered all of Chile south of approximately present-day Puerto Montt during the South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a
Ice sheets are bigger than ice shelves or glaciers. An ice shelf is a thick floating platform of ice that forms where a Glacier or Ice sheet flows down to a Coastline and onto the ocean surface "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Masses of ice covering less than 50,000 km² are termed an ice cap. An ice cap is an Ice mass that covers less than 50 000 km² of land area (usually covering a highland area 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. An ice stream is a region of an Ice sheet that moves significantly faster than the surrounding Ice.
The present-day polar ice sheets are relatively young in geological terms. The Antarctic Ice Sheet first formed as a small ice cap (maybe several) in the early Oligocene, but retreating and advancing many times until the Pliocene, when it came to occupy almost all of Antarctica. An ice cap is an Ice mass that covers less than 50 000 km² of land area (usually covering a highland area The Oligocene is a geologic epoch of the Paleogene period and extends from about 33 The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends The Greenland ice sheet did not develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. 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. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Plants are living Organisms belonging to the kingdom Plantae.
Contents |
Antarctic ice sheet
The Antarctic ice sheet is the largest single mass of ice on Earth. The Antarctic ice sheet is one of the two Polar ice caps of the Earth. It covers an area of almost 14 million km² and contains 30 million km³ of ice. Around 90% of the fresh water on the Earth's surface is held in the ice sheet, and, if melted, would cause sea levels to rise by 61. 1 meters. [2] In East Antarctica the ice sheet rests on a major land mass, but in West Antarctica the bed is in places more than 2,500 meters below sea level. East Antarctica, also called Greater Antarctica, is one of the two major regions of the Antarctic Continent, lying on the Indian Ocean side of The West Antarctic Ice Sheet ( WAIS) is the segment of the continental ice sheet that covers West (or Lesser Antarctica, the portion of Antarctica Mean sea level (MSL is the average (mean height of the Sea, with reference to a suitable reference surface It would be seabed if the ice sheet were not there. "Ocean Floor" redirects here For the 2001 song by Audio Adrenaline, see Lift (Audio Adrenaline album.
Greenland ice sheet
The Greenland ice sheet occupies about 82% of the surface of Greenland, and if melted would cause sea levels to rise by 7. The Greenland Ice Sheet is a vast body of ice covering 171 million km² roughly 80% of the surface of Greenland. Greenland (Kalaallit Nunaat meaning "Land of the Greenlanders" Grønland is a self-governing Danish Province located between the 2 metres. [2] Estimated changes in the mass of Greenland's ice sheet suggest it is melting at a rate of about 239 cubic kilometres (57. 3 cubic miles) per year. [3] These measurements came from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite, launched in 2002, as reported by BBC News in August 2006 [4]. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The goal of the Gravity Recovery And Climate Experiment ( GRACE) space mission is to obtain accurate global and high-resolution determination of both the static and the time-variable
Ice sheet dynamics
Ice motion is dominated by the movement of glaciers, whose activity is controlled by a number of processes. Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Their motion is dominated by cyclic surges interspersed with longer periods of inactivity, on both hourly and centennial time scales.
Predicted effects of global warming
The Greenland, and probably the Antarctic, ice sheets have been losing mass recently, because losses due to melting and outlet glaciers have exceeded accumulation due to snowfall. According to the IPCC, loss of Antarctic ice sheet mass and Greenland ice sheet mass contributed, respectively, about 0. 21 ± 0. 35 and 0. 21 ± 0. 07 mm/year to sea level rise between 1993 and 2003. Sea-level rise is an increase in Sea level. Multiple complex factors may influence this change [5]
The IPCC projects that ice mass loss from melting of the Greenland ice sheet will continue to outpace accumulation from snowfall. Accumulation from snowfall on the Antarctic ice sheet is projected to outpace losses from melting. However, loss of ice mass on the Antarctic ice sheet may continue, if there is sufficient loss of ice mass via outlet glaciers. According to the IPCC, scientific understanding of dynamical ice flow processes is currently "limited".
External links
- United Nations Environment Programme: Global Outlook for Ice and Snow
- http://www.nasa.gov/vision/earth/environment/ice_sheets.html
References
- ^ Glossary of Important Terms in Glacial Geology. Retrieved on 2006-08-22. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 392 - Arbogast has Eugenius elected Western Roman Emperor.
- ^ a b Some physical characteristics of ice on Earth, Climate Change 2001: Working Group I: The Scientific Basis. Intergovernmental Panel on Climate Change (IPCC)
- ^ Rasmus Benestad et al.: The Greenland Ice. Realclimate.org 2006
- ^ Greenland melt 'speeding up', BBC News, 11 August 2006
- ^ Richard B. Alley et al.:Summary for Policymakers, A report of Working Group I of the Intergovernmental Panel on Climate Change
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic