Arctic

For the ships, see MV Arctic, SS Arctic, USS Arctic. For other uses, see Arctic (disambiguation)
Location of the Arctic
Artificially coloured topographical map of the Arctic region
MODIS image of the Arctic
Arctic countries based on countries or countries territories bordering the Arctic Circle
The nations which comprise the Arctic region.

The Arctic ( /ˈɑːrktɪk/ or /ˈɑːrtɪk/) [1] [Note 1] is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Alaska ( United States), Canada, Finland, Greenland ( Denmark), Iceland, Norway, Russia, and Sweden. Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost-containing tundra. Arctic seas contain seasonal sea ice in many places.

The Arctic region is a unique area among Earth's ecosystems. For example, the cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions. In recent years, Arctic sea ice decline has been caused by global warming. [3] [4] Life in the Arctic includes organisms living in the ice, zooplankton and phytoplankton, fish and marine mammals, birds, land animals, plants and human societies. [5] Arctic land is bordered by the subarctic.

Definition and etymology

The word Arctic comes from the Greek word ἀρκτικός (arktikos), "near the Bear, northern" [6] and that from the word ἄρκτος (arktos), meaning bear. [7] The name refers either to the constellation Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere, or to the constellation Ursa Minor, the "Little Bear", which contains Polaris, the Pole star, also known as the North Star. [8]

There are a number of definitions of what area is contained within the Arctic. The area can be defined as north of the Arctic Circle (66° 33'N), the approximate southern limit of the midnight sun and the polar night. Another definition of the Arctic is the region where the average temperature for the warmest month (July) is below 10 °C (50 °F); the northernmost tree line roughly follows the isotherm at the boundary of this region. [9] [10]