Antarctica
Antarctica is a continent of extremes and is quite unlike any of the other six global continents.
CLIMATE
It is the coldest continent with an average temperature of nearly -50C. This is caused by two main factors. Firstly the angle of incidence of the sun’s rays is much lower at or near the poles which causes the heat energy from the sun to be spread over a far larger ground area than, say, at the equator where the angle of incidence is always 90 degrees. Secondly the ice and snow covering Antarctica cause a high proportion of the sun’s energy to be reflected. The coldest temperature ever recorded was at the Russian station Vostok and was close to -90C. Only on the Antarctic Peninsula are temperatures above zero encountered.
It has the highest average altitude. Much of Antarctica is at very high altitude (10,000 feet or more) but this is not due to the underlying geography of the continent. It is caused by the thickness of the ice cap which in places is more than 4500 metres and averages 2200 metres. The weight of the ice cap is so great that the underlying rock has been depressed by up to 25% of the thickness of the ice by a process called isostasy.
It is the windiest continent. Antarctica is subject to fierce winds of up to 200 mph. These winds are known as catabatic winds which are caused by the movement of cold air downhill from the continent’s interior to compensate for warm air rising.
It is the driest continent. Antarctica is a desert. In fact it is the driest desert on earth with average precipitation of less than 50mm per year (about half that of the Sahara desert). Why, then, is there such an accumulation of ice? The reason is that the maximum temperature of the continent’s interior is always well below freezing point so whatever precipitation falls (as snow) never melts.
THE ICE
About 98% of Antarctica is covered by a permanent icecap which accounts for about 90% of all the world’s ice and about 70% of the world’s fresh water. The pressure of the icecap causes a very slow movement of the ice towards the edges of the continent. When it reaches the edge, the ice extends over the sea to form what are known as ice shelves. The largest ice shelf is the Ross Ice Shelf which is about the size of France. Eventually and from time to time large pieces of ice break free and float away as icebergs.
Are we losing the Antarctic Ice Cap? Well, it would certainly be a disaster of epic proportions if the whole of the icecap were to melt but fortunately even the most alarming global warming estimates would suggest that this would take up to 10,000 years. There is certainly a shift in the pattern of the icecap with large areas of Western Antarctica (near the peninsula) and its ice shelves melting. But this is perhaps more than compensated for by the expansion of the ice cap in Eastern Antarctica. At Australia’s Davis station the ice thickness has recently been measured at 1.89 miles, the highest in 10 years. (Antarctic Climate and Ecosystems Co-Operative Research Centre.)
ICEBERGS
Most Antarctic icebergs are caused by the breaking off of parts of the ice shelves in all parts of Antarctica. Such icebergs are called ‘tabular icebergs’ because of their regular flat topped appearance but they can be immense. Icebergs can be several miles long and wide, the largest recorded was nearly the size of Wales. A height of 50 metres above sea level is not uncommon and this means a total thickness of 450-500 metres.
LIFE IN ANTARCTICA
The interior of the continent is devoid of all life forms. No mammals, no reptiles, no birds, no insects, no trees, no plants, no grass – virtually no micro-organisms. Around the peninsula, where the temperature rises slightly above freezing during the summer and parts may be ice free, there is some plant life.
All animal life is sea based and can be seen on the continent only near the coastal areas. This includes penguins, seals, whales and several types of seabird notably albatrosses, petrels and skuas. The ocean is very rich in fish especially the small crustacean krill.
No humans live on Antarctica so the continent has an official population of zero. There are some scientific research stations on which staff resides for periods (even overwintering). Most of these are close to the coastal regions although the USA maintains a large station at the South Pole and Russia has an interior station named Vostok.
GEOGRAPHY AND POLITICS
Antarctica is about 13,000,000 square kilometres in size. This is roughly 1.5 times the size of Europe. It is surrounded by the Southern Ocean and the winter freezing of the sea effectively more than doubles the size of the continent at the most extreme time (September). Most of this sea ice melts and in February may be a mere 4,000,000 square kms.
At roughly 60 degrees of latitude there is an imaginary line in the Southern Ocean surrounding the continent called the Antarctic Convergence. This is the point where the cold waters flowing North from Antarctica meet the warmer waters flowing South from the Pacific, Atlantic and Indian Oceans. North of the convergence, the water is warmer (about 4 degrees), there is rarely any sea ice and there is an abundance of oxygen in the water. This allows a rich growth of algae which in turn feeds the zooplankton (especially krill). Krill (a small shrimp like creature) is the life form with the greatest biomass (species total weight) of any creature on earth. It provides food for seals, whales, penguins and other birds in abundance which is why islands near the convergence are very rich in wildlife.
Antarctica has no countries and has been governed by the Antarctic Treaty since 1959. 47 countries are signatories to this treaty which prohibits territorial claims and has strict rules to ensure that the continent is used only for peaceful purposes and that its environment is protected. The treaty covers all land south of 60 degree latitude.
EXPLORATION
The heroic age of exploration was about 100 years ago and the two most well-known British names were Robert Falcon Scott and Ernest Shackleton. Their most famous expeditions, known by the name of the ships were:
Discovery (1902-3) led by Scott who attempted with Shackleton to reach the South Pole. They were forced to abandon the attempt after illness and shortage of food and fuel. Although they had travelled further South than anyone before, they only reached a latitude of 82 degrees – some 480 miles short of their objective.
Nimrod (1908-9) Shackleton led this expedition which was rather more successful and he also broke a record for furthest South but was forced to turn back less than 100 miles from the South Pole
Terra Nova (1910-12) Scott’s most famous but tragic expedition. His attempt on the pole with companions Bowers, Evans, Wilson and Oates was successful in that he reached 90 degrees South on January 17th 1912. However they were devastated to discover that their rival, the Norwegian Amundsen, had beaten them to it by 5 weeks. On the return journey Scott and his 4 companions perished in a blizzard just 11 miles from safety.
Endurance (1914-16) was Shackleton’s attempt at a traverse of the Antarctic Continent. This went badly wrong when his ship was crushed in the sea ice of the Weddell Sea before he and his team had even reached the land. His epic struggle to get himself and his men back to safety after more than 18 months of hardships and disasters is one of the most inspiring of all adventure stories and includes his famous voyage from Elephant Island to South Georgia in the lifeboat, the James Caird.