Antarctica

Antarctica, lying at the southernmost tip of the world, is the coldest, driest, and windiest continent. Ice covers 98 percent of the land, and its 5,100,000 square miles (13,209,000 square kilometers) cover nearly one-tenth of Earth's land surface, about the same size as Europe and the United States combined. Despite its barren appearance, Antarctica and its surrounding waters and islands teem with life, and the continent plays a significant role in the climate and health of the entire planet.

Although humans have never settled on Antarctica because of its brutal climate, since its discovery in the early 1800s explorers and scientists have traveled across dangerous seas to study the continent's winds, temperatures, rocks, wildlife, and ice. While some countries have tried to claim parts of the continent as their own, Antarctica is an independent

continent protected by international treaty from ownership by any one country.

Overview

Archaeologists and geologists believe that millions of years ago Antarctica was part of a larger continent called Gondwanaland. About 200 million years ago, as a result of shifting in the plates of Earth's crust, Gondwanaland broke apart and created the separate continents of Antarctica, Africa, Australia, South America, and India. Antarctica is currently centered roughly on the geographic South Pole, the point where all south latitudinal lines meet. It is the most isolated continent on Earth, 600 miles (1,000 kilometers) from the southernmost tip of South America and more than 1,550 miles (2,500 kilometers) away from Australia.

Seventy percent of Earth's freshwater is frozen atop the continent. These icecaps reflect warmth from the Sun back into the atmosphere, preventing the planet from overheating. Huge icebergs break away from the stationary ice and flow north to mix with warm water from the equator, producing currents, clouds, and complex weather patterns. Creatures as small as microscopic phytoplankton and as large as whales live on and around the continent, including more than 40 species of birds.

Geology. Almost all of Antarctica is under ice, in some areas by as much as 2 miles (3 kilometers). The ice has an average thickness of about 6,600 feet (2,000 meters), which is higher than most mountains in warmer countries. This grand accumulation of ice makes Antarctica the highest continent on Earth, with an average elevation of 7,500 feet (2,286 meters). If all of this ice were to melt, global sea levels would rise by about 200 feet (65 meters), flooding the world's major coastal ports and vast areas of low-lying land.

Under the ice, the Antarctic continent is made up of mountains. The Transantarctic Mountains are the longest range on the continent, stretching 3,000 miles (4,828 kilometers) from the Ross to Weddell Seas. Vinson Massif, at 16,859 feet (5,140 meters), is the highest mountain peak. The few areas where mountains peak through the ice are called nunataks.

Around several parts of the continent, ice forms vast floating shelves. The largest, known as the Ross Ice Shelf, is about the same size as Texas or Spain. Since the shelves are fed by glaciers on the continent, the resulting shelves and icebergs are made up of frozen freshwater. The largest glacier on Earth, the Lambert Glacier on the eastern half of the continent, is 25 miles (40 kilometers) wide and more than 248 miles (400 kilometers) long.

Gigantic icebergs are a unique feature of Antarctic waters. They are created when huge chunks of ice separate from an ice shelf, a cliff, or a glacier, a process known as calving. Icebergs can be amazingly huge; an iceberg measured in 1956 was 208 miles (335 kilometers) long by 60 miles (97 kilometers) wide, and was estimated to contain enough freshwater to supply the water needs of London, England, for 700 years. Only 10 to 15 percent of an iceberg normally appears above the water's surface. As these icebergs break away from the continent, new ice is added to the continent by snowfall.

Icebergs generally flow northward and, if they don't become trapped in a bay or inlet, will reach the Antarctic convergence, the point in the ocean where cold Antarctic waters meet warmer waters. At this point, ocean currents usually sweep the icebergs from west to east until they melt. An average iceberg will last several years before melting.

Climate. Antarctica is the windiest and coldest place on Earth. The wind can gust up to 200 miles per hour, or twice as hard as the average hurricane. Little snow actually falls in Antarctica; because the air is so cold, what snow that does fall turns immediately to ice. In winter, temperatures may fall to −100°F (−73°C). The world's record for lowest temperature was recorded on Antarctica in 1960, when it fell to −126.9°F (−89.8°C).

Strong winds constantly travel over the continent as cold air races over the high ice caps and then flows down to the coastal regions. Winds associated with Antarctica blizzards commonly gust to more than 120 miles (193 kilometers) per hour, and are among the strongest winds on Earth. Even at its calmest, the continent's winds can average 50 to 90 miles (80 to 145 kilometers) per hour.

Even with all its ice and snow, Antarctica is the driest continent on Earth based on annual precipitation amounts. The constantly cold temperatures have allowed each year's annual snowfall to build up without melting over the centuries. Along the polar ice cap, annual snowfall is only 1 to 2 inches (2.5 to 5 centimeters). More precipitation falls along the coast and in the coastal mountains, where it may snow 10 to 20 inches (25 to 51 centimeters) per year.

Plants and animals. The Antarctic continent is nearly barren due to the persistently cold and dry climate. Hardy plants like pearlwort (a flowering plant), mosses, and lichen (a combination of algae and fungi) are found along the coast and on the Antarctic Peninsula, the warmest part of the continent.

Few creatures can survive Antarctica's brutal climate. Life in the sea and along the coast of Antarctica and its islands, however, is often abundant. Several seabirds make the Antarctic their home, including 24 species of petrels, small seabirds that dart over the water and nest in rocks along the shore. A wide variety of animals make the surrounding waters their home, from zooplankton (small floating organisms) to seals and whales.

Of all the animals, penguins are the primary inhabitants of Antarctica. Believed to have evolved 40 to 50 million years ago, they have oily feathers that provide a waterproof coat and a thick layer of fat for insulation. Penguins' bones are solid, not hollow as are those of most flying birds. Solid bones add weight, making it easier for penguins to dive into the water for food. These bones also prevent them from flying, but because they do not have predators that can live in the brutally cold climate, they do not need to fly. Thus their wings have evolved over the centuries to resemble flippers or paddles.

Exploration of the continent

Greek philosopher Aristotle hypothesized more than 2,000 years ago that Earth was round and that the Southern Hemisphere must have a land-mass large enough to balance the lands in the Northern Hemisphere. He called the proposed land mass Antarktikos, meaning the opposite of the Arctic.

The continent remained a mystery until English navigator and explorer James Cook crossed the Antarctic Circle and sailed around the continent in 1773. While he stated that the land was uninhabitable because of the ice fields surrounding the continent, he noted that the Antarctic Ocean was rich in whales and seals. For the next 100 years, hunters exploited this region for the fur and oil trade, traveling ever farther and farther south.

In 1895, the first landing on the continent was accomplished by the Norwegian whaling ship Antarctic. The British were the first to spend a winter on Antarctica, in 1899. By 1911, a race had begun to see who would first reach the South Pole, an imaginary geographical center point at the bottom of Earth. Again, a Norwegian, Roald Amundsen, was the first to reach it, on December 14, 1911.

Scientific exploration

The International Geophysical Year (IGY), from July 1, 1957, to December 31, 1958, was a planned cooperative venture by scientists from 56 nations to study a variety of subjects. During this venture, 12 nations conducted research in Antarctica, setting up base camps in various locations, some of which are still used today. Topics of research included

the pull of gravity, cosmic rays, the southern lights, and changes in the atmosphere.

Since these cooperative research projects, several agreements have been signed to ensure that political conflicts do not arise concerning research and use of Antarctica. The Antarctic Treaty was signed on December 1, 1959, by the 12 nations involved in the IGY projects, and made official on June 23, 1961, after each country ratified it within their own governments. As of April 1994, 42 countries had committed themselves to the spirit of cooperation outlined in the treaty, making it one of the most successful international agreements ever created.

The treaty requires all countries to give up any territorial claims, to exchange scientific investigations and results, and to stop all military activity and weapons testing (including nuclear testing and the disposal of radioactive wastes) in the region. Any disputes that cannot be settled by negotiation or arbitration are sent to the International Court of Justice for settlement. The treaty thus sets aside 10 percent of Earth as a nuclear-free, demilitarized zone.

In 1991, the countries added the Protocol on Environmental Protection to the treaty. The Protocol grew out of concerns that poor habits by researchers and increasing numbers of tourists were increasing pollution problems on the continent. It requires countries to protect the continent's ecosystem (its community of plants and animals), paying particular attention to the production and disposal of wastes.

Current events

A wide variety of research is continuing on Antarctica. Astronomer's find the continent's cold temperatures and high altitude allow for a clearer view of the stars and planets. Antarctica is also the best place to study interactions between solar wind and Earth's magnetic field, temperature circulation in the oceans, unique animal life, ozone depletion, ice zone ecosystems, and glacial history. Buried deep in Antarctica ice lie clues to ancient climates, which may provide answers to whether Earth is due for global warming or the next ice age.

[ See also Greenhouse effect ; Ozone ; Plate tectonics ]