Ice cap climate
Encyclopedia
Polar climate
Regions with a polar climate are characterized by a lack of warm summers . Regions with polar climate cover over 20% of the Earth. The sun shines 24 hours in the summer, and barely ever shines at all in the winter...
where the temperature never or almost never exceeds 0 °C (32 °F). The climate covers the areas around the poles, such as Antarctica and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
, as well as the highest mountaintops. Such areas are covered by a permanent layer of ice and have no vegetation, but they do have animal life, that usually feeds from the oceans. Due to their high latitudes, icecap climates experience 24 hours of sun in the summer and no sunshine in winter, the midnight sun
Midnight sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous...
and polar night
Polar night
The polar night occurs when the night lasts for more than 24 hours. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnight sun, occurs when the sun stays above the horizon for more than 24 hours.-Description:...
.
Description
Under the Köppen climate classificationKöppen climate classification
The Köppen climate classification is one of the most widely used climate classification systems. It was first published by Crimea German climatologist Wladimir Köppen in 1884, with several later modifications by Köppen himself, notably in 1918 and 1936...
, the ice cap climate is denoted as EF. Ice caps are defined as a climate with no months above 0 °C (32 °F). Such areas are found around the north and south pole, and on the top of the highest mountains. Since the temperature never exceeds the melting point of water, any snow or ice that accumulates remains there permanently, over time forming a large ice sheet
Ice sheet
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² , thus also known as continental glacier...
.
The ice cap climate is distinct from the tundra climate, or ET. A tundra climate has a summer season with temperatures consistently above freezing for several months. This summer is enough to melt the winter ice cover, which prevents the formation of ice sheets. Because of this, tundras have vegetation, while ice caps do not.
Ice cap climate is the world's coldest climate, and includes the coldest places on Earth. Vostok, Antarctica is the coldest place in the world, having recorded a temperature of -89.2 C.
Ice sheets
The constant freezing temperatures cause the formation of large ice sheets in ice cap climates. These ice sheets, however, are not static, but slowly move off the continents into the surrounding waters. New snow and ice accumulation then replaces the ice that is lost. Precipitation is nearly non-existent in ice cap climates. It is never warm enough for rain, and usually too cold to generate snow. However, wind can blow snow on to the ice sheets from nearby tundras.The ice sheets are often miles thick. Much of the land located under the ice sheets is actually below sea level, and would be under the ocean if the ice is removed. However, it is the weight of the ice itself that forces this land below sea level. If the ice was removed, the land would rise back up in an effect called post-glacial rebound
Post-glacial rebound
Post-glacial rebound is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostasy...
. This effect is creating new land in formerly ice cap areas such as Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
.
The extreme pressure exerted by the ice allows for the formation of liquid water at low temperatures that would otherwise result in ice, while the ice sheet itself insulates liquid water from the cold above. The causes the formation of sub-glacial lakes, the largest being Lake Vostok
Lake Vostok
Lake Vostok is the largest of more than 140 subglacial lakes found under the surface of Antarctica. The overlying ice provides a continuous paleoclimatic record of 400,000 years, although the lake water itself may have been isolated for 15 to 25 million years. The lake is named after the...
in Antarctica.
Geologic history
Icecap climates have only existed in ice ages. There have been at least five such ice ages in the Earth's past. Outside these ages, the EarthEarth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
seems to have been ice-free even in high latitudes. By the geologic definition, Earth is currently in an ice age
Quaternary glaciation
Quaternary glaciation, also known as the Pleistocene glaciation, the current ice age or simply the ice age, refers to the period of the last few million years in which permanent ice sheets were established in Antarctica and perhaps Greenland, and fluctuating ice sheets have occurred elsewhere...
, in that the planet has permanent ice caps. Factors that cause ice ages include changes to the atmosphere, the arrangement of continents, the energy received from the sun, volcanos, and meteor impacts.
The current era is believed to be the only time in Earth's history with ice caps at both poles. The Antarctic ice cap was formed after Antarctica split from South America, allowing the formation of the Antarctic Circumpolar Current
Antarctic Circumpolar Current
The Antarctic Circumpolar Current is an ocean current that flows from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current...
. The Arctic ice cap was partially caused by the Azolla event
Azolla event
The Azolla event occurred in the middle Eocene period, around , when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean...
, where a large number a ferns in the ocean died, sank, and never decayed, which trapped carbon dioxide beneath the ocean.
There is a hypothesis that around 650 million years ago, the entire planet was frozen, called Snowball Earth
Snowball Earth
The Snowball Earth hypothesis posits that the Earth's surface became entirely or nearly entirely frozen at least once, some time earlier than 650 Ma . Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical...
. Essentially the entire planet had an ice cap climate. However, this theory is disputed, and even proponents suggest there was an area of periodic melting near the equator.
Locations
The two major areas with ice cap climates are Antarctica and GreenlandGreenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. Some of the most northern extremes of Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
also have ice cap climates. In addition, a large portion of the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
near the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
remains frozen year round, effectively making it an icecap climate.
North Pole
The Arctic OceanArctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
is located over the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
. As a result, the northern polar ice cap is the frozen ocean. The only large landmass to have an icecap climate is Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
, but several smaller islands near the Arctic Ocean also have permanent ice caps.
Ice cap climates aren't nearly as common on land at the North Pole as in Antarctica. This is because the Arctic Ocean moderates the temperatures of the surrounding land, making the extreme cold seen in Antarctica impossible. In fact, the coldest places in the northern hemisphere are in subarctic climates in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, such as Verkhoyansk
Verkhoyansk
Verkhoyansk is a town in Verkhoyansky District of the Sakha Republic, Russia, situated on the Yana River, near the Arctic Circle, from Yakutsk. Population: There is a river port, an airport, a fur-collecting depot, and the center of a reindeer-raising area....
, which are much farther inland and lack the ocean's moderating effect.
South Pole
The continent of Antarctica is centered around the South PoleSouth Pole
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where the Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of the Earth and lies on the opposite side of the Earth from the North Pole...
. Antarctica is surrounded on all sides by the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
. The Southern Ocean circles the entire planet at its latitude. As a result, high-speed winds circle around Antarctica, preventing warmer air from temperate zones from reaching the continent.
While Antarctica does have some small areas of Tundra on the northern fringes, the vast majority of the continent is extremely cold and permanently frozen. Because it is climactically isolated from the rest of the Earth, the continent has extreme cold not seen anywhere else, and weather systems rarely penetrate into the continent.
Extraterrestrial
Mars, like Earth, has ice caps at its poles. In addition to frozen water, Mars ice caps also have frozen carbon dioxide, commonly known as dry iceDry ice
Dry ice, sometimes referred to as "Cardice" or as "card ice" , is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue...
. In addition, Mars has seasons similar to Earth. The North Pole of Mars has a permanent water ice cap and a winter-only dry ice cap. On the south pole, both the water and carbon dioxide are permanently frozen.
Europa
Europa (moon)
Europa Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of ice and is one of the smoothest in the Solar System. This surface is striated by cracks and...
, a moon of Jupiter, is covered with a permanent sheet of water ice, similar to Antarctica. Scientists theorize that it may have sub-glacial lakes similar to those seen in Antarctica.
Life
There is very little life in ice cap climates. Vegetation can not grow on ice, and is non-existant. However, ice caps do have significant animal life. Most of this life feeds on life on the surrounding oceans. Well known examples are polar bears and penguins. The interior of continents are devoid of animal life.Antarctica has several subglacial lakes underneath its ice sheet. Scientists have theorized that there may be life forms living in these lakes. However, as of 2011, no one has drilled into these lakes to take a sample of the water and determine if there is life there. Scientists are particularly worried about accidentally contaminating the subglacial lakes with life forms from outside.