Polar ice cap
Polar ice caps (often short polar caps ) are ice sheets that blanket the poles of a planet. They are found both on Earth and on Mars.
Earth
The polar ice caps in the North Pole ( Arctic ice cap ) and southern region ( Antarctic ice sheet ) consist of glacial ice and sea ice. They form in response to various climatic factors, such as local temperatures, sea and air currents, and especially the humidity.
The term of the polar ice cap has become the norm in the current language. In technical terms are understood under the term ice cap a plateau glacier, which is always on a land mass. Larger masses of ice on the Antarctic continent and Greenland ice sheets are called. In common parlance, is a polar ice cap, but also added counted the sea ice.
Arctic ice cap
The Arctic ice cap is the umränderte of drift ice pack ice zone of the Arctic Ocean.
The central, the northernmost regions of the Arctic Ocean ( Arctic Ocean ) have a year-round ice sheet. This is not fixed, but subject to a steady drift, which is inter alia caused by different ocean currents. The peripheral, further south areas of the Arctic Ocean covered by ice, the extent of seasonal off and increases. In more southern latitudes also a seasonal variable Treibeiszone connects.
The thickness of the ice is seasonal and ranges from two meters in the outskirts of up to four meters at the North Pole - on average it is about 3 m. At places where the pack ice drifts against coasts, also ice sheets of up to eight meters can form starch.
The solid pack ice zone is umschiffbar and 2006 ranged up to the north coast of Greenland. It extends over the Ellesmere Island, Axel Heiberg Island and Bank island to the north coast of Alaska and the Wrangel Island. Outside the pack ice zone are the arctic islands Iceland, Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, the New Siberian Islands, Victoria Island, Devon Island and Baffin Island, which are also seasonal ice or surrounded by drift ice.
Large seasonal ice sheets formed in the Arctic after the Paleocene / Eocene Thermal Maximum about 47 million years ago. First multi-year ice was about 13 million years ago to 14.
Only the polar research in the 20th century was the final proof that the Arctic Ocean - was around the North Pole completely iced over and there was the Arctic ice cap - contrary to the theory of the ice-free Arctic Ocean. The first tunnel under the Arctic ice cap was in 1958 by the USS Nautilus instead. 1987 succeeded the Soviet icebreaker Sibir became the first ship to advance through the arctic ice cap to the North Pole.
The proportion of perennial, thick ice that forms the Arctic ice cap is plummeting. While in the past the pack ice made up the bulk of the ice predominates since 1996 in the period of maximum sea-ice extent, the proportion of one-year ice. The current loss of ice seems, at least compared to the last few thousand years, to be exceptional and can not be explained by natural causes of past changes. In addition to long-range oscillations such as the North Atlantic Oscillation, global warming is a cause. Had models previously nor suggests the ice melt to about 2080, so might already from 2030 to 2040 the Arctic sea ice will be gone in the summer.
Antarctic ice cap
The Antarctic ice cap consists of vast glaciers that cover 98% of the Antarctic and reach a thickness of up to five kilometers. Is the largest ice earth. Because it is. Around ice on the mainland and not, as in the Arctic, sea ice is around, one also speaks of the Antarctic ice sheet The Antarctic ice sheet was formed about 43 million years ago.
Mars
The polar caps of Mars consist mostly of frozen carbon dioxide with a small amount of water. In the vicinity of the (smaller) southern polar cap, however, contain large amounts of frozen water.