Wednesday, 23 April 2008
Antarctica is a continent capped by an inland ice sheet up to 4.8 km thick, containing about 90% of the world's fresh water. The ice sheet is so heavy that it has pushed the land below sea level in places. Because of the thickness of the ice sheet, Antarctica has the highest average altitude of all of the continents.
The South Pole is 1235 km from the closest coastline, and is situated high on the polar plateau. Here it may be as cold as 75C, but the world record lowest temperature is from an even more remote Antarctic station, Vostok, which logged -89C.
Antarctica is a cold desert, with snowfall equivalent to only 150 mm of water each year. This snow builds up gradually, and ice flows towards the coast as huge glaciers. In many places, these extend out over the sea as massive ice shelves.
Only about 0.4% of the surface of Antarctica is free of snow and ice. The tops of mountain chains stick up through the ice - the highest is Mount Vinson, 4900 m above sea level.
The Southern Ocean is a continuous belt of sea surrounding Antarctica. In winter, over half of the Southern Ocean freezes over. Although this seawater ice is only about 1 m thick, it has a significant effect on ocean and atmospheric circulation. Nearly all of the sea ice melts in summer.
There are no native peoples in Antarctica. Eighteen countries operate year-round scientific research stations on the continent and the surrounding islands, and during summer as many as 10,000 scientists and support staff work there, but only about 1000 in winter. Tourists also visit Antarctica during the summer to enjoy the spectacular scenery and abundant wildlife. Currently there are about 14,000 visitors per year.
Antarctica is a continent for science . All countries working in Antarctica carry out scientific research, in a surprising range of physical and biological sciences, from the vastness of space to the minute scale of micro-organisms. Activities are regulated by the Antarctic Treaty, which has been in force since 1959 and is signed by all countries operating there. The Treaty reserves the continent for peaceful purposes, and all military and industrial activities are banned.