![]() Īccording to the National Snow and Ice Data Center, "since 1979, winter Arctic ice extent has decreased about 4.2 percent per decade". When the ice breaks off (calves) it forms icebergs scattered around the northern Atlantic. In addition, the Greenland ice sheet covers about 1.71 million km 2 and contains about 2.6 million km 3 of ice. The area covered by sea ice ranges between 9 and 12 million km 2. One-year ice is usually about 1 meter thick. ![]() Portions of the ice that do not melt seasonally can get very thick, up to 3–4 meters thick over large areas, with ridges up to 20 meters thick. Additionally, in geologic time scales, the ice caps may grow or shrink due to climate change.Įarth's North Pole is covered by floating pack ice ( sea ice) over the Arctic Ocean. Seasonal variations of the ice caps takes place due to varied solar energy absorption as the planet or moon revolves around the Sun. Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions, resulting in lower surface temperatures.Įarth's polar caps have changed dramatically over the last 12,000 years. For example, Earth's polar caps are mainly water ice, whereas Mars's polar ice caps are a mixture of solid carbon dioxide and water ice. This causes the term "polar ice cap" to be something of a misnomer, as the term ice cap itself is applied more narrowly to bodies that are over land, and cover less than 50,000 km 2: larger bodies are referred to as ice sheets. There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap, nor any geological requirement for it to be over land, but only that it must be a body of solid phase matter in the polar region. Polar ice cap on Mars, seen by the Hubble Space TelescopeĪ polar ice cap or polar cap is a high- latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. ![]()
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