The fifth largest and by far the coldest of the seven continents. It is centred on the South Pole, located mostly within the Antarctic Circle, covered with ice (which in places is more than 2000 metres thick) and surrounded by sea ice, particularly during the winter. The outer limits of Antarctica are defined by the Antarctic Convergence. It is, in effect, a cold desert, with an average annual precipitation in the interior of about 50 millimetres. Climate in the interior is dominated by extreme cold and light snowfall, and temperatures are milder and precipitation is much higher (up to about 380 millimetres a year) around the coastal fringe. Over 95% of the land surface is currently covered by ice, and the ice cover is variable in thickness but sometimes thicker than about 2000 metres. This thick ice cover makes Antarctica the highest continent overall, with an average elevation of about 2300 metres above sea level. Wildlife on the ice‐covered areas is extremely limited; the most prominent examples are the penguins (particularly Adelie and emperor penguins) which breed on ice and live on ice and in the surrounding oceans. The sea has more abundant life, including six species of seal and large numbers of whales which feed on krill (small, shrimp‐like crustaceans that swarm in dense shoals and feed on tiny diatoms). The human population of Antarctica is extremely small, because there is no native population and most residents are short‐term scientific visitors. Antarctica is widely regarded as the last great wilderness. Until relatively recently its natural environments have been preserved more by lack of exploitation (because the continent is so remote, inaccessible, and uninviting) than by purposeful action. But this is changing, as geological exploration reveals more details of the large deposits of valuable mineral resources (particularly coal, oil, and natural gas) beneath the cold continent and its surrounding continental shelf. Pressures on Antarctic marine resources are also mounting, with extensive commercial exploitation of whales and krill. West Antarctica contains enough ice to raise sea level by between five and six metres, and there is mounting concern about the rapid melting of this ice, which is occurring faster than previously thought, and appears to be associated with, if not directly caused by, global warming. See also Antarctic Treaty.