In the icy world, nothing can compare in size or importance to the Antarctic, which is almost a complete cryo-continent, covering about 14 million square kilometres, about as much as Mexico and the continental US put together. It has been a separate continent in the region of the South Pole for over 50 million years and has the most hostile environment of any area of the Earths surface.
If you recall Chapter 5, you already know part of the problem. In the Arctic and Antarctic, winds start out at the poles and spread outwards. The air that makes them up starts out dry. In the Antarctic, it stays that way because it is blowing over land. So the Antarctic is a desert. Most of it has precipitation that would add up to less than 50mm a year if it fell as rain, which of course it usually does not.
The Sun never gets far above the Antarctic horizon, and it vanishes completely for up to six months of the year. In addition, the Antarctic runs up to over 4000m above sea level. This makes it even colder. Finally, because 97 percent of the Antarctic continent is covered in ice and snow, it reflects away most of the solar energy that does manage to arrive. The albedo (reflectivity) of snow can be up to 0.85, whereas the albedo of the Earth at large, as we saw in Chapter 1, is only about 0.37. All this means that the Antarctic has an average temperature of -49°C.
The ice sheets of the Antarctic are tricky to measure. But in recent years, observers have converged on a figure of about 30 million cubic kilometres for the amount of ice they contain. The perfectionists at the US Geological Survey plump for 30.1098 million, which is taking accuracy too far. This means, as one enthusiast put it, that chopping it up would give everyone on Earth a piece of ice the size of the Great Pyramid at Giza. More significant than this improbable feat is that if all this ice melted, sea level would rise by about 70m. It also adds up to 70 percent of the world s fresh water and 90 percent of its ice.
Near the edge of the Antarctic continent, ice sheets are grounded on rock below sea level. But further out, they float and are called ice shelves. These advance and retreat in winter and summer respectively and are a source of icebergs. The main body of the continent is divided into the East and West Antarctic Ice Sheets. The West Sheet is the one you tend to hear about in news reports. This is because large parts of it rest on rock below sea level. If the Earth warms, it is especially likely to melt or break up, with serious effects on sea level. However, this applies to parts of the East Sheet too. In addition, there is the Antarctic Peninsula, pointing in the direction of South America.
It may be the coldest and least inviting continent, but how many others change their shape completely over the year as Antarctica does? Between summer and winter, it grows in size as the sea freezes. In the height of summer, its land area is supplemented by up to 3 million square kilometres of ice shelf, with the Ross Ice Shelf the biggest. But in the winter, this area can grow by another 15 million square kilometres.
As well as all this ice, the region around the Antarctic continent contains an abundance ot islands. Many were used tor whaling stations in the past and are now home to scientific bases. The most astonishing is Ross Island in the Ross Sea. Although most of the Antarctic is tectonically quiet, it does have some volcanic and seismic activity. On Ross Island it breaks out in the form of Mount Erebus, a full-scale volcano rising to 3800m above sea level. Erebus has been continuously active for decades and, inevitably, there is now a webcam for you to have a look.
On the coasts and islands of Antarctica the heights above sea level are lower, there is sea to moderate the climate, and the Sun gets that much higher in the sky. So these parts are more temperate and are home to more life, including all of the continents bigger life forms. They include birds such as the skua and big sea mammals such as seals that are known from elsewhere in the world, as well as penguins, unique fishing and swimming birds. The oceans off the continent are also full of fish and other life ranging in size from krill – shrimp-like crustaceans – up to walruses, sea-lions and whales.
The inland parts of Antarctica are not one blank and unvarying sheet of ice, however. In 1903, the British explorer Robert Falcon Scott discovered the Taylor Valley, the first of the Antarctic dry valleys to be found, and called it “the valley of the dead”. The dry valleys are areas where the wind scours away the snow to leave bare rock and sand, and they are the most significant ice-free areas of the continent. But even the dry valleys are less barren than Scott thought. We now know that they are home to nematode worms and that there is a simple but effective ecology of bacteria in the valleys’ permanently ice-covered lakes. The valleys are the nearest thing the Earth has to the conditions today on the surface of Mars. The fact that life exists there is regarded as an indicator that it could survive on Mars. But there is a world of difference between life hanging on in the dry valleys and life originating there. The life we see there is a highly adapted version of living systems that got their start in more temperate zones of the Earth.
Even more astounding has been the discover)' of over seventy liquid water lakes far below the ice surface of the Antarctic. With the Russians still in pole position in Antarctic research, it is no surprise that the biggest such lake is called Vostok, Russian for east. It was found in 1996, partly by observations of the surface above. As the ice above Vostok is floating on the water below, it is noticeably flatter than the rest of the local landscape. Lake Vostok lies below 4000m of ice, but stays liquid because of heat Irom the Earth below and pressure from above. It is about 250km long, 40km wide and about 400m deep, or, as NASA puts it, about the size of Lake Ontario. It seems to be in an area of tectonic activity, upping the amount of heat it receives from below, a little like an under-ice version of Lake Baikal in Siberia. But it has been hermetically sealed off from the rest of the world even more effectively than Baikal and for even longer, perhaps tor more than a million years.
This means that Vostok is one of the most precious conservation assets on Earth. Whether it is possible to take a look without introducing organisms from the outside and wrecking it remains to be seen. So tar, investigative drilling has stopped a couple of hundred metres short of the lake. But evidence has been found there that suggests the lake may be home to microbial forms of life.
Even the thick ice that covers most of the continent is far from dead. It looks completely barren but the ice cores drilled out of it contain abundant bacteria.
The world's largest lab
The abundance of life, especially krill and wrhales, in the oceans around Antarctica has long attracted the human hunter. And in recent years increasing numbers of tourist ships have been visiting the region. But plans to exploit minerals in the Antarctic oceans and continent have failed to take off for commercial reasons and because of environmental concerns. The result is that the Antarctic has been left almost entirely to the scientists, and has become the worlds biggest science lab. As we have seen, the Antarctic ice is about 4500m deep at its thickest point. This means that it has taken time to build up. In the process, it has turned into an invaluable record of the Earths past climate. Ice cores drilled in the Antarctic by Russian scientists have produced a 200,000-year-plus account of the temperature of the Earth, using the varying composition of the ice as a thermometer.
In addition, up on the central plateau, astronomers use telescopes and cosmic ray detection devices to probe the outer reaches of the universe. On the peninsula and the islands, as well as in the dry valleys and the oceans, there is vigorous biological research. And throughout the continent, weather data is gathered that feeds climate models.
Indeed, while Antarctica swells in winter and shrinks in summer, its human population does the opposite. In summer they number thousands, mainly scientists and tourists, while in winter only a few hundred hardy souls stay on.
Those who do so are in one of the few places in the world that you can visit without a passport or a visa and where you are unlikely to meet armed force of any kind. Despite the lines on the map showing supposed Norwegian, British, French, New Zealand, Chilean, Argentinian and Australian claims to parts of the continent, only the Latin Americans have shown any interest in a real political land grab. Even their enthusiasm seems to have ebbed as the Antarctic’s lack of commercial value has become apparent. Under the Antarctic Treaty, all land claims polewards ot 60°S are suspended. In any case, the US rejects them all, which makes them effectively valueless. So these lines on the map will probably continue to have no border guards or customs posts.