Antarctica covers about 14-million square kilometres, or 10% of the earth's land surface. A permanent ice cap covers 98% of the land, with an average depth of 2 km and a maximum depth of 4,5 km. The main ice-free areas are around the coast, but in many places the icecap extends off shore in vast ice shelves. About 90% of the world's fresh water is stored in this icecap and if it were to melt the world's sea level could rise by an estimated 55 metres. A place of extremes, Antarctica boasts the world's lowest temperature of -89,2 degrees centigrade and winds of up to 320 km/hour.
Antarctica plays an important role in the earth's climate and weather patterns, and is of vital interest for scientists studying the earth's evolution and atmosphere. Layers of ice, compacted over millions of years, provide a history of the earth's climate. By studying cores drilled out of the ice, scientists can detect temperature changes over the centuries. Trapped air bubbles record changes in the concentration of carbon dioxide in the atmosphere, essential to our understanding of global warming. Ice cores have shown how radioactivity and lead pollution have increased in the atmosphere since 1945.
Each summer, increased light levels and nutrient rich upwellings support blooms of phytoplankton (floating microscopic marine algae). These support vast numbers of krill, particularly Antarctic krill, a 70 mm long shrimp-like creature. Antarctic krill forms dense concentrations, called swarms, during the Antarctic summer. These can be several kilometres across and 20 metres deep. At night these swarms light up and the sea becomes a mass of living, blue-green light. Krill is the main food source for five species of whale (whose migration is linked to its life cycle), three species of seal, twenty species of fish, three species of squid, and many species of birds, including penguins. These animals feed at different stages of the krill's life-cycle, at different times of the year, in different places and at different depths, thus achieving a delicate balance of supply and demand.
During the winter months, Weddell seals live permanently under the ice, using sonar to locate their food and find their way back to their breathing holes. The emperor penguin breeds at the end of summer, broods its eggs through the winter and hatches them in spring, so that the chicks become independent just when the food is most abundant in the summer seas.
* about 100 fish species;
* six seal species - comprising two-thirds of the world's seals;
* several whale species, including the blue, fin, sei, humpback, sperm and right whales;
* more that 50 species of birds - the total population of birds breeding on Antarctica is estimated at over 100-million, including seven penguin species, which make up the greatest percentage.
* Elephant seals and fur seals were hunted close to extinction in the last century. These species have since increased in numbers, although elephant seals are now decreasing on some sub- Antarctic islands.
* The blue, sei, fin, humpback, sperm whales and right whales were all hunted almost to extinction from the 1920s to the 1960s. The blue whale's estimated population is now less than 5% of their original numbers, and after years of protection there seems to have been no noticeable increase.
A modern threat to Antarctica is the fishing of krill and finfish. Several nations, including Japan and the former Soviet Union, have caught large quantities of krill since the 1960s. There are hopes that krill could be a new food source for the world's people. Overfishing of krill could harm all the creatures dependant upon it.
* an uncontrolled influx of tourists;
* destruction of the ozone layer and the resulting increase in ultra-violet radiation - this could kill the phytoplankton on which krill feed, and thus affect the food web of the Southern Ocean;
* mining of the continent's anticipated mineral wealth.
The Antarctic Treaty was negotiated in 1959 by 12 founder nations (including South Africa) for the purpose of promoting international peace and scientific cooperation in the region.
The Treaty provides the primary legal framework for all decision- making in the area south of 60 degrees latitude. It applies to the land and ice-shelves but does not cover the high seas. There are now 38 member countries of the Treaty. In 1992, a new Environmental Protocol added to the Antarctic Treaty banned the exploitation of minerals in Antarctica for many years.
Two hundred organisations in 35 countries have come together in the Antarctic and Southern Ocean Coalition (ASOC) to protect Antarctica by monitoring, informing and lobbying in domestic and international forums. Members of ASOC argue that the severity of weather conditions, fragility of the marine resources, the area's role in atmospheric and oceanic circulation, and the fact that Antarctica is the earth's last unspoiled wilderness are reasons for proclaiming the area an International Wilderness Park free from commercial exploitation.
* Antarctica has no native human inhabitants. About 900 people brave the six months of extreme cold and permanent darkness in winter to operate the 34 scientific stations. This number increases to 3 000 people during the summer months. By contrast, 2 million people live within the Arctic in the northern hemisphere.
SECRETS OF THE SEAS. Illustrated guide to marine life off southern Africa. A. Payne and R. Crawford (eds). Vlaeberg Publishers, Cape Town, 1992.
NORTH POLE, SOUTH POLE: A GUIDE TO THE ECOLOGY AND RESOURCES OF THE ARCTIC AND ANTARCTIC. B. Stonehouse. Prion, London, 1993.
All books are available from Russel Friedman Books, PO Box 73, Halfway House 1685. Tel. 011-7022300/1.
Dolphin Action and Protection Group. Save Antarctica Campaign. PO Box 22227, Fish Hoek, 7975. Tel. 021-782 5845.
South African Museum. PO Box 61, Cape Town, 8000. Tel 021-243330.