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Encyclopedia > Ice sheet

An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²).[1] The only current ice sheets are in Antarctica and Greenland; during the last ice age 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. This article is about the geological formation. ... This article is about water ice. ... Square kilometre (US spelling: Square kilometer), symbol km², is an SI unit of surface area. ... A square mile is an English unit of area equal to that of a square with sides each 1 statute mile (≈1,609 m) in length. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... LGM can refer to: Last Glacial Maximum Little Green Men The first pulsar was initially dubbed LGM-1 for Little Green Men This is a disambiguation page: a list of articles associated with the same title. ... 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 United States, between ~ 90,000 and ~ 18,000 years before the present day. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... The Wisconsin (in North America), Devensian (in the British Isles), Midlandian (in Ireland), Würm (in the Alps), and Weichsel (in northern central Europe) glaciations are the most recent glaciations of the Pleistocene epoch, which ended around 10,000 BCE. The general glacial advance began about 70,000 BCE, and... For other uses, see Europe (disambiguation). ... The Patagonian Ice Sheet was a large ice sheet that covered all of Chile south of approximately present-day Puerto Montt during the Last Glacial Maximum. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...


Ice sheets are bigger than ice shelves or 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. Ross Ice Shelf 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. ... This article is about the geological formation. ... An ice cap is a dome-shaped ice mass that covers less than 50,000 km² of land area (usually covering a highland area). ...


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. Geothermal power is electricity generated by utilizing naturally occurring geological heat sources. ... 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. The Greenland ice sheet did not develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation. 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. An ice cap is a dome-shaped ice mass that covers less than 50,000 km² of land area (usually covering a highland area). ... The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... A glaciation (a created composite term meaning Glacial Period, referring to the Period or Era of, as well as the process of High Glacial Activity), often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ... For other uses, see Fossil (disambiguation). ... For other uses, see Plant (disambiguation). ...

Contents

Antarctic ice sheet

A satellite composite image of Antarctica

The Antarctic ice sheet is the largest single mass of ice on 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. It would be seabed if the ice sheet were not there. Download high resolution version (1282x1100, 257 KB) this is an image of antarticta from space File links The following pages link to this file: Antarctica ... Download high resolution version (1282x1100, 257 KB) this is an image of antarticta from space File links The following pages link to this file: Antarctica ... A satellite composite image of Antarctica The Antarctic ice sheet is the largest single mass of ice on Earth. ... East Antarctica, also called Greater Antarctica, (80° S 80° E) is one of the two major regions of Antarctica, lying on the Indian Ocean side of the Transantarctic Mountains and comprising Coats Land, Queen Maud Land, Enderby Land, Mac. ... The West Antarctic Ice Sheet (WAIS) blankets the continent of Antarctica west of the Transantarctic Mountains, covering the area called Lesser Antarctica. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... The seabed (also sea floor, seafloor, or ocean floor) is the bottom of the ocean. ...


Greenland ice sheet

Map of Greenland

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[3]. 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 [1]. These measurements came from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite, launched in 2002, as reported by BBC News, 11 August 2006. Download high resolution version (492x802, 66 KB)Greenland map, based on a CIA map. ... Download high resolution version (492x802, 66 KB)Greenland map, based on a CIA map. ... Outline Map of Greenland with ice sheet depths. ... This article is about the American space agency. ... 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 components of the Earths gravity field. ...


Predicted effects of global warming

Both the Antarctic and Greenland 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 each contributed about .21 mm/year to the sea level rise between 1993 and 2003.[4] IPCC is the science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), to evaluate the risk of climate change brought on by humans, based mainly on... Sea level measurements from 23 long tide gauge records in geologically stable environments show a rise of around 20 centimeters per century (2 mm/year). ...


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

  1. ^ Glossary of Important Terms in Glacial Geology. Retrieved on 2006-08-22.
  2. ^ http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113
  3. ^ http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113
  4. ^ http://www.ipcc.ch/SPM2feb07.pdf

  Results from FactBites:
 
Ice sheet - Wikipedia, the free encyclopedia (475 words)
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²).
The only current ice sheets are Antarctic and Greenland; during the last ice age 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.
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.
Ice sheet - definition of Ice sheet in Encyclopedia (359 words)
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres).
The only current ice sheets are Antarctic and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada and North America while the Weichselian ice sheet covered northern Europe.
The Greenland ice sheet occupies about 82% of the surface of Greenland, and if melted would contribute approximately 7.2 m of sea level rise.
  More results at FactBites »

 
 

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