Ice cap climate

Under the Köppen climate classification, the ice cap climate is denoted as EF. Ice caps are defined as a climate with no months above 0 °C (32 °F).[2] Such areas are found around the north and south pole, and on the top of many high mountains. Since the temperature never exceeds the melting point of ice, any snow or ice that accumulates remains there permanently, over time forming a large ice sheet.

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. With an average temperature of −55.2 °C (−67.4 °F), Vostok, Antarctica is the coldest place in the world, and has also recorded the lowest temperature, −89.2 °C (−128.6 °F).[3] The following chart indicates the average and record temperatures in this research station through a year:

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 onto the ice sheets from nearby tundras.

Ice sheets are often miles thick. Much of the land located under ice sheets is actually below sea level, and would be under the ocean if the ice were removed. 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. This effect is creating new land in formerly ice cap areas such as Sweden.

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 subglacial lakes, the largest being Lake Vostok in Antarctica.

Ice cap climates only occur during icehouse Earth periods. There have been five such periods in the Earth's past. Outside these periods, the Earth seems to have been ice-free even in high latitudes.[9][10] Factors that cause icehouse Earth include changes to the atmosphere, the arrangement of continents, and the energy received from the sun. Earth is currently in an icehouse period.

The two major areas with ice cap climates are Antarctica and Greenland. Some of the most northern islands of Canada and Russia, along with some regions and islands of Norway's Svalbard Archipelago also have ice cap climates. In addition, a large portion of the Arctic Ocean near the North Pole remains frozen year round, effectively making it an icecap climate.

A polar bear with cub

There is very little surface life in ice cap climates. Vegetation cannot grow on ice, and is non-existent except in the warmer fringes that occasionally peak above freezing, even then it is confined to mosses and lichen. However, the fringes of ice caps do have significant animal life. Most of this life feeds on life in the surrounding oceans. Well known examples are polar bears in the northern region and penguins in Antarctica.

Antarctica has several subglacial lakes underneath its ice sheet. Scientists have theorized that there may be life forms living in these lakes. In the summer of 2011–2012, Russian scientists drilled an ice core into Lake Vostok in Antarctica, but the core has not yet been analyzed. Scientists are particularly worried about accidentally contaminating the subglacial lakes with life forms from outside.