Polar ice caps
The polar ice caps in the Arctic - (Arctic ice cap) and the Southern Region ( Antarctic ice sheet ) consist of glacier ice and sea ice . They are formed depending on various climatic factors, such as local temperatures, sea and air currents, and especially the humidity.
The term “polar ice cap” has become commonplace. In technical terms, the term ice cap means a plateau glacier that is always on a land mass. Larger ice masses on the Antarctic continent and on Greenland are known as ice sheets . In common parlance, however, sea ice is also included in a polar ice cap.
Arctic ice cap
The central, most northerly regions of the Arctic Ocean (Arctic Ocean) have a year-round ice armor. This is not stationary, but is subject to a constant drift , which u. a. caused by various ocean currents . The peripheral, more southern areas of the Arctic Ocean are covered by pack ice, the extent of which increases and decreases with the season. In more southern latitudes there is a seasonally changeable drift ice zone.
The thickness of the ice layer varies with the seasons and ranges from two meters in the peripheral areas to four meters at the North Pole - on average it is around 3 m. In places where the pack ice drifts against the coast, ice sheets up to eight meters thick can also form.
The fixed pack ice zone can be navigated around and reached as far as the north coast of Greenland in 2006 . It extends over Ellesmere Island , Axel Heiberg Island and Banks Island to the north coast of Alaska and Wrangel Island . Outside the pack ice zone are the arctic islands of Iceland , Franz Josef Land , Novaya Zemlya , Severnaya Zemlya , New Siberian Islands , Victoria Island , Devon Island and Baffin Island , which are also seasonally icy or surrounded by drift ice.
Large seasonal ice sheets formed in the Arctic after the Paleocene / Eocene temperature maximum about 47 million years ago. The first multi-year ice formed around 13 to 14 million years ago.
It was not until the polar research of the 20th century that the final proof that the Arctic Ocean - contrary to the theory of the ice-free Arctic Ocean - was completely frozen around the North Pole and formed the Arctic Ice Cap there. The first crossing under the Arctic Ice Cap was in 1958 by the USS Nautilus . In 1987, the Soviet icebreaker Sibir became the first ship to advance through the Arctic ice sheet to the North Pole.
The proportion of perennial, thick ice that forms the Arctic ice cap is rapidly declining. While the pack ice used to make up the main part of the ice, since 1996, during the period of maximum sea ice expansion, the proportion of annual ice has predominated. The current ice loss appears to be extraordinary, at least when compared to the last several thousand years, and cannot be explained by the natural causes of past changes. In addition to wide-ranging oscillations such as the North Atlantic Oscillation , global warming is a cause. While models previously suggested that the ice would melt by around 2080, the Arctic sea ice could have disappeared in summer by 2030–2040.
Antarctic ice cap
The Antarctic Ice Cap consists of extensive glaciers that cover 98% of Antarctica and are up to five kilometers thick. It is the largest mass of ice on earth. Since it is ice on the mainland and not, as in the Arctic, sea ice, it is also referred to as the Antarctic ice sheet . The Antarctic ice cap formed around 43 million years ago.
The polar caps of the planet Mars consist largely of frozen carbon dioxide with a small amount of water. In the vicinity of the (smaller) southern polar cap, however, there are also large amounts of frozen water.
- Alfred Wegener Institute for Polar and Marine Research
- Consequences of global warming in the Arctic
- Polar climate
- Frank Press and Raymond Siever: General Geology. Spektrum Akademischer Verlag , 3rd edition, October 2003.
- Sven Titz: Riviera in the Arctic . In: Spectrum of Science . October 2006.
- Polar Sea Ice Status on a Daily Basis
- zeit.de 2011: Consequences of melting ice on the poles
- Arctic change: ice - sea ice (English)
- Cryosphere Today With satellite imagery and trends (English) University of Illinois at Urbana-Champaign
- Current extent of the polar ice caps Sea ice portal in German with current measured values and status in the course of the season
- Polyak et al .: History of sea ice in the Arctic . In: Quaternary Science Reviews . 2010, p. 1757-1778 .
- Stroeve et al .: The Arctic's rapidly shrinking sea ice cover: a research synthesis . In: Climatic Change . 2012, p. 1005-1027 , doi : 10.1007 / s10584-011-0101-1 ( PDF ). PDF ( Memento of the original from February 1, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- Parkinson and Cavalieri: Arctic sea ice variability and trends, 1979-2006 . In: Journal of Geophysical Research . 2008, doi : 10.1029 / 2007JC004558 .
- Mark Kinver: Arctic ice thickness 'plummets'. BBC, October 28, 2008, accessed November 15, 2013 .