Ice sheet

"Continental glacier" redirects here. For the glacier located in Wyoming, see Continental Glacier.
One of Earth's two ice sheets: The Antarctic ice sheet covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It has an average thickness of over 2 kilometers.[1]

In glaciology, an ice sheet, also known as a continental glacier,[2] is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi).[3] The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. 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.

Even stable ice sheets are continually in motion as the ice gradually flows outward from the central plateau, which is the tallest point of the ice sheet, and towards the margins. The ice sheet slope is low around the plateau but increases steeply at the margins.[4]

Increasing global air temperatures due to climate change take around 10,000 years to directly propagate through the ice before they influence bed temperatures, but may have an effect through increased surface melting, producing more supraglacial lakes. These lakes may feed warm water to glacial bases and facilitate glacial motion.[5]

In previous geologic time spans (glacial periods) there were other ice sheets. During the Last Glacial Period at Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America. In the same period, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America.

  1. ^ "Ice Sheets". National Science Foundation.
  2. ^ American Meteorological Society, Glossary of Meteorology Archived 2012-06-23 at the Wayback Machine
  3. ^ "Glossary of Important Terms in Glacial Geology". Archived from the original on 2006-08-29. Retrieved 2006-08-22.
  4. ^ Cite error: The named reference IPCC_AR6_AnnexVII was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference IPCCc4 was invoked but never defined (see the help page).