I | INTRODUCTION |
Antarctica, fifth largest of Earth’s seven continents.
Antarctica surrounds the South Pole and is a place of extremes. It is the
southernmost, coldest, iciest, driest, windiest, most remote, and most recently
discovered continent. Nearly the entire landmass lies within the Antarctic
Circle. Air temperatures of the high inland regions fall below -80°C (-110°F) in
winter and rise only to -30°C (-20°F) in summer. Massive ice sheets built up
from snow over millions of years cover almost all of the continent and float in
huge ice shelves on coastal waters. In winter frozen sea water (sea ice) more
than doubles the size of the Antarctic ice cap. Antarctica's vast areas of ice
on land and on sea play a major role in Earth’s climate and could be strongly
affected by global warming. The melting of Antarctic ice could dramatically
raise global sea level.
Antarctica means “opposite to the Arctic,”
Earth’s northernmost region. Antarctica is completely encircled by the Southern
Ocean. The entire area south of the Antarctic Convergence zone where cold
Antarctic waters sink below warmer waters on the northern boundary of the
Southern Ocean is referred to as the Antarctic region.
The small human presence on Antarctica is made
up of visiting scientists, support staff, and tourists. The last continent to be
discovered, Antarctica remained hidden behind barriers of fog, storm, and sea
ice until it was first sighted in the early 19th century (see Polar
Exploration). Because of the extreme cold and the lack of native peoples,
forests, land animals, and obvious natural resources, the continent remained
largely neglected for decades after discovery. Scientific expeditions and seal
hunters had explored only fragments of its coasts by the end of the 19th
century, while the interior remained unknown. Explorers first reached the South
Pole in 1911, and the first permanent settlements—scientific stations—were
established in the early 1940s. From that time the pace of exploration and
scientific research has accelerated rapidly. In the mid- to late 20th century,
the region’s majestic scenery and wildlife began to attract increasing numbers
of tourists.
Seven nations—Argentina, Australia, the United
Kingdom, Chile, France, New Zealand, and Norway—claim territory in Antarctica.
Other nations, including the United States and Russia, do not acknowledge these
claims and make no claims of their own, but reserve rights to claim territory in
the future. Since 1961 the continent has been administered under the Antarctic
Treaty, an international agreement to preserve the continent for peaceful
scientific study.
II | LAND AND CLIMATE OF ANTARCTICA |
The continent of Antarctica is shaped
somewhat like a comma, with a round body surrounding the pole and a tail curving
toward South America. The round portion, lying mainly in the Eastern Hemisphere,
makes up East Antarctica. The tail and its thickened base, located entirely in
the Western Hemisphere, form West Antarctica. East Antarctica includes the
regions of Queen Maud Land, Enderby Land, and Wilkes Land; West Antarctica
includes Palmer Land, Ellsworth Land, and Marie Byrd Land. Antarctica
lies 1,000 km (600 mi) from South America, its nearest neighbor; 4,000 km (2,500
mi) from Africa; and 2,500 km (1,600 mi) from Australia.
With an area of 14 million sq km (5.4 million
sq mi), Antarctica is larger than either Europe or Australia. Its average
elevation of more than 2,000 m (6,500 ft) is over twice that of Asia, the next
highest continent. However, much of this mass is ice. Below this ice, East
Antarctica is a landmass about the size of Australia, and West Antarctica is a
collection of islands. Only 2.4 percent of the total continental area is exposed
rock. Exposed areas include the peaks of several mountain ranges and other
smaller scattered outcrops, both of which poke through the ice cover, as well as
dry valleys, glacier-carved areas that are kept clear of snow by gusty
winds. Only about 2 percent of the coast is exposed cliffs or beaches; the rest
is made up of ice cliffs that extend beyond the end of the continental
rock.
The Ross and Weddell seas indent the
thickened base of West Antarctica where it meets East Antarctica, while the
Amundsen and Bellingshausen seas lie at West Antarctica’s outer edge. Numerous
bays also indent the outer edge of East Antarctica, creating a jagged coastline.
The geographic South Pole lies near the
center of the continent in East Antarctica. This point is where all map lines of
longitude converge at the southern end of Earth’s axis of rotation. Distinct
from the geographic south pole is the south magnetic pole, where the lines of
force of Earth’s magnetic field emerge vertically, arching upward over the
planet to enter Earth again at the north magnetic pole. The south-seeking end of
a compass needle points to the south magnetic pole. The south magnetic pole is
currently located off the Adélie Coast of East Antarctica, but was on land when
it was first recorded in 1909. The south magnetic pole has migrated gradually
out to sea with changes in the fields, a phenomenon known as polar wandering.
The south geomagnetic pole is the hypothetical location of the magnetic pole if
Earth’s magnetic field were a perfect bar magnet. The south geomagnetic pole is
located near Vostok station in East Antarctica.
A | Land of Ice |
The total volume of the ice sheet covering
Antarctica is estimated at 29 million cu km (7 million cu mi), or about 90
percent of the world’s ice. (Greenland contains about 8 percent of the global
ice mass, with most of the rest found as glaciers in mountainous regions around
the world.) The Antarctic ice sheet holds about 70 percent of all the freshwater
on Earth. If the entire ice sheet melted, the oceans of the world would rise by
60 m (200 ft). Some 11 percent of the ice sheet consists of ice shelves—massive
floating slabs of permanent ice fringing the continent—that are anchored to the
rock and extend into the surrounding ocean. The largest, Ross Ice Shelf, is
about the size of France. The Antarctic ice sheet has an average thickness of
2,160 m (7,090 ft); its greatest recorded depth is more than 4,700 m (15,400
ft).
Antarctica’s ice sheet formed over
millions of years. As new snow falls, it compresses the layers of older snow
beneath it into ice. The physical characteristics of the ice sheet are
constantly changing as new ice forms and slides outward toward the coasts. Large
masses of moving ice known as glaciers move down the continent’s five major
drainage systems in two ways. If there is a layer of water between the glacier
and the bedrock beneath it, the whole glacier can slide under the force of
gravity. Alternatively, the weight of the accumulated snow and ice can cause the
ice crystals of the glacier to form into layers, which glide over one another.
Glaciers flow either into ice shelves or directly out to the edges of the
continent, where portions break off and form floating masses called icebergs
(see Ice: Icebergs). Carried by circumpolar currents and
prevailing winds, these icebergs drift westward around the continent and then
northward to the Antarctic Convergence before gradually breaking up and melting
upon contact with warmer waters.
Icebergs that break away from Antarctica
and melt raise sea level by adding water that was locked up as land ice.
Increased snow fall that adds to the Antarctic ice sheet could offset the
melting of icebergs and glaciers, however. The flow of glaciers to the sea has
been accelerating in parts of West Antarctica. Large portions of ice shelves
have also broken off. Since ice shelves float on water, they would not raise sea
level when they melt. However, rising sea levels in the future would lift ice
shelves and lead to more break ups and melting of ice that was once on
land.
In addition to icebergs and ice shelves,
ocean waters close to the continent contain floating sea ice. In contrast to
icebergs and ice shelves, which are frozen fresh water, sea ice is frozen sea
water. As sea water freezes, it expels salt, which collects as concentrated
brine between the ice crystals. The briny water eventually drains from the
underside of the sea ice, creating a downward flow of heavier salty water. As a
result, sea ice that survives for a number of months can be virtually fresh.
Some sea ice is attached to the land (fast ice) and some drifts with wind
and currents (pack ice). Sea ice melts and freezes seasonally, covering
up to 21 million sq km (8 million sq mi) in late winter and only 5 million sq km
(2 million sq mi) in summer. Unlike melting glaciers and ice sheets, melting sea
ice does not directly raise sea level. However, loss of sea ice exposes darker
ocean water to sunlight and heats the ocean.
The maximum area of sea ice surrounding
Antarctica each winter varies from year to year. A marked decline during the
1970s appears to have reversed in more recent decades, except in the Antarctic
Peninsula area. This area has lost almost 40 percent of its sea ice since the
start of the 1980s. Sea ice is important to marine life. Krill feed on algae
that live under the sea ice and are released when the ice melts in spring and
summer. In turn, many marine animals feed on krill. Emperor penguins breed on
flat expanses of sea ice close to land during the winter. Seals give birth on
sea ice in early spring.
Ice on land and on sea reflects sunlight
back into space, which has a cooling effect on Earth’s climate. Shrinking ice
shelves or reduced sea ice in summer allows the exposed dark ocean to absorb
more heat, raising temperatures.
B | Land Regions of Antarctica |
During the early part of the Mesozoic Era
(which lasted from 251 million to 65 million years ago) Antarctica was a part of
Pangaea, the giant supercontinent that included nearly all land on Earth. About
240 million years ago Pangaea began to split into two giant landmasses called
Laurasia and Gondwanaland (also called Gondwana). Gondwanaland consisted of the
present continent of Antarctica along with Australia, South America, Africa, and
the Indian subcontinent. Gondwanaland itself began to break up about 185 million
years ago. Antarctica gradually moved towards the South Pole. About 80 million
years ago, Antarctica split from Australia and became an isolated land mass that
drifted southward into its polar position. Climatic cooling began about 34
million years ago during the Oligocene Epoch. Coupled with mountain building,
this cooling initiated the formation of permanent ice on land, resulting in the
Antarctic ice sheet. The giant ice sheet in East Antarctica has been a stable
feature for about 15 million years, beginning in the Miocene Epoch. The ice
sheet on West Antarctica has collapsed and reformed a number of times during the
same period.
East Antarctica makes up about two-thirds
of the continent’s area. The land beneath the ice consists of a basement complex
of ancient gneisses, schists, and other metamorphic rocks overlaid by sediments
from the Cambrian and Permian periods. Containing evidence of tropical forests
and deserts prior to the more recent glacial conditions, these layers reflect
the region’s complex climatic history. Covering the land is a huge, complex ice
dome rising from coastal plains to a high plateau more than 4,000 m (13,000 ft)
in elevation. The Transantarctic Mountains stretch 3,500 km (2,200 mi) along the
entire western flank of East Antarctica, separating it from West Antarctica.
This range holds back the plateau ice of East Antarctica like a massive dam,
penetrated by glaciers that flow into the Ross and Filchner-Ronne ice shelves to
the west. High peaks—some rising to more than 4,300 m (14,000 ft)—poke through
the ice sheet, and other portions of the range are dry valleys that are free of
ice. Toward the Indian and Pacific ocean coasts lie several minor ice domes and
lower plateaus, some penetrated by other mountain ranges.
The remaining third of the continent, West
Antarctica, consists of a much lower, undulating ice sheet covering a complex of
mountainous islands. The Antarctic Peninsula, the “tail” of land reaching toward
South America, was formed by the same geologic processes that formed the Andes
Mountains on that continent. Many islands, including the South Shetland Islands,
lie off the Antarctic Peninsula. Deep trenches and basins beneath the ice
separate the islands of West Antarctica. Vinson Massif, the highest point in
Antarctica, has an elevation of 4,897 m (16,066 ft) and lies in the Sentinel
Range near the Filchner-Ronne Ice Shelf. Several active volcanoes, including
Mount Erebus on Ross Island, dot coastal and island areas. The multilayered land
formations of West Antarctica, folded and transformed by geologic structural
deformations, reveal a distinct, more turbulent geological history than that of
East Antarctica. These formations consist of a Precambrian basement covered by
volcanic sediments from the Carboniferous Period, Mesozoic Era, and Cenozoic
Era. These volcanic sediments are in turn covered by plant-bearing Jurassic and
later Cenozoic sediments.
Soils are extremely rare in Antarctica,
occurring only in ice-free areas where fine rock debris can accumulate. In
summer, the soils provide a damp substrate for plants such as lichens and moss,
and for microorganisms. The continent’s two species of flowering plants may gain
a foothold in favorable conditions found in West Antarctica. There is no
Antarctic equivalent of Arctic tundra.
Unusual geological features on Antarctica
include dry valleys and lakes buried deep beneath the ice sheet. Dry valleys are
ice-free valleys carved by glaciers that have retreated during the past few
thousand years. The valleys receive little or no snow and are mainly surfaced by
rock or gravel, with summer streams and almost permanently frozen lakes. Unusual
plants, animals, and microbes survive in the simple ecosystems. Much larger
bodies of water called subglacial lakes have been found under the ice sheet. The
largest known is Lake Vostok, which covers about 11,655 square km (5,400 square
mi) in area, similar in size to Lake Ontario. Such lakes may contain interesting
microbes that are unknown elsewhere, but scientists have not yet found ways of
drilling down to to the lakes without severely contaminating them. A complex
system of subglacial lakes may also affect how fast ice sheets and glaciers move
to the coast and break up as icebergs.
C | Climate and Weather in Antarctica |
Antarctica has several climates, all cold
but differing considerably in severity. East Antarctica’s high plateau region
yields the lowest year-round temperatures due to its relatively high elevation.
The world’s lowest yearly air temperatures, typically –88°C (–126°F), are
recorded in late August at Russia’s Vostok station. In coastal regions latitude
is more significant than elevation. The higher the latitude (that is, the closer
to the pole) the lower the average temperatures. The west coast of the Antarctic
Peninsula and the neighboring islands have the mildest climates, with average
January temperatures above freezing. Some of the fastest warming on Earth has
occurred around the Antarctic Peninsula, with a rise of almost 3°C (5°F)
over the past 50 years. Elsewhere in Antarctica, however, temperatures and
precipitation have remained relatively steady over the same time period.
The entire region south of the Antarctic
Circle, which is the parallel of latitude at 66°30’ south, experiences at least
one day of continuous daylight during the Southern Hemisphere’s summer (around
December 21) and one day of continuous darkness during the winter (around June
21). The interior of Antarctica has almost continuous daylight during the summer
and darkness during the winter. In coastal areas farther north, there are fewer
days of continuous daylight and darkness, and sunrises and sunsets occur more
frequently.
Precipitation falls mainly as snow or ice,
with occasional rain in coastal areas. Very little precipitation falls on the
high plateau. Average annual accumulations of 50 mm (2 in) there make it one of
the world’s driest deserts. Successive low-pressure systems around the coasts
and islands bring heavier snow, which is packed down by wind and its own weight
to form ice. Winds are light and variable on the plateaus, rarely reaching more
than 30 km/h (20 mph), but are strong and persistent closer to the coasts.
Katabatic, or downslope, winds blow cold, dense air down the steep slopes from
the interior highlands onto the lower ice slopes.
Chemical reactions that occur at high
altitudes in the atmosphere have affected the ozone layer over the Antarctic
region, creating an ozone hole. During the cold polar night, naturally forming
clouds of nitrogen-containing compounds and water vapor in the stratosphere over
Antarctica react with synthetic chemicals such as chlorofluorocarbons and
bromine halocarbons. When the mix of chemicals is exposed to sunlight in spring,
additional chemical reactions with chlorine or bromine remove ozone from the
stratosphere. Preventing the release or reducing the levels of the chlorine and
bromine-containing chemicals would allow the ozone layer to recover.
D | Optical Phenomena in Antarctica |
Antarctica experiences many unusual
atmospheric optical phenomena. Most spectacular is the aurora australis
(southern lights), caused by entry into the upper atmosphere of streams of
charged particles (mainly protons and electrons) from the Sun. Deflected by the
Earth’s magnetic field, the particles collide with atoms and molecules of
atmospheric gases 100 to 140 km (60 to 90 mi) above the Earth’s surface. This
produces light in characteristic rays, bands, and rings of various hues. Within
the southern auroral zone—a wide circle about 4,000 km (about 2,000 mi) in
diameter and centered around the geomagnetic pole (the south end of the
axis of the geomagnetic field that surrounds the Earth)—auroral displays are
visible almost every winter night, including the 24-hour-long polar night.
Refraction of light from the Sun and Moon
by concentrations of ice crystals in the lower atmosphere produces iridescent
clouds in the sky and rainbow-like halos around the Sun and Moon. Similar
atmospheric distortions produce colored disks resembling the Sun and Moon—called
parhelia, or sun dogs, and parselene respectively—as well as colored
arches in the sky. More rarely, high altitude ice clouds called noctilucent
clouds are visible after sunset. Dry atmosphere chilled by contact with the cold
surface of Earth gives rise to spectacular mirages, in which distant objects are
raised above the horizon to appear misleadingly close.
E | Vegetation in Antarctica |
Almost completely covered by thick ice,
Antarctica has very little land available for soils to form or vegetation to
settle. Existing soils were formed late in the continent’s geologic history and
have little organic content or water-holding capacity. Isolation from other
continents makes it difficult for new types of vegetation to spread to
Antarctica. Constant low temperatures, high winds, and lack of moisture
discourage all but the hardiest plants, which may be capable of active growth
for only a few days per year. These factors limit plant life in Antarctica
almost entirely to protists (simple, often one-celled organisms), algae,
lichens, and mosses. Only two known species of flowering plants, both found only
on the Antarctic Peninsula and neighboring islands, grow in Antarctica. The
continent has no equivalent of Arctic tundra, which supports a greater variety
of plant life: Antarctica’s richest vegetation compares with the northernmost,
scarcest Arctic polar desert vegetation. Nevertheless, patches of vegetation
grow on all known rocky outcrops in Antarctica, to within 290 km (180 mi) of the
South Pole. Snow algae grow on snow and ice surfaces close to the coast,
especially along the Antarctic Peninsula where seabird droppings and sea spray
provide nutrients. Minute lichens grow within the surface layers of crystalline
rocks, and microbes are present in snow, soils and ice-covered lakes.
Antarctic waters support other types of
vegetation. Coastal seaweeds thrive on and around islands near the Antarctic
Convergence, but are inhibited farther south where sea ice scrapes the shores.
The cold waters of the Southern Ocean support masses of phytoplankton—minute
floating plants including diatoms, dinoflagellates, and other algae—that
proliferate in summer, especially in areas where upwelling brings nutrient-rich
waters to the surface (see Marine Life: Environmental Factors).
Phytoplankton provides a rich source of food for marine animals.
F | Animal Life in Antarctica |
The harsh climate and sparse vegetation of
Antarctica’s land regions support only microscopic animals and primitive
insects. Protozoa, nematodes, tardigrades, and other minute forms inhabit damp
soils. Other invertebrate species include springtails and mites. The wingless
midge, which grows up to 12 mm (0.47 in) long, is the largest land animal.
In contrast to the land, the Southern Ocean
supports a wide variety of animal life, which all depends directly or indirectly
on the phytoplankton of the surface waters. Zooplankton—including krill,
copepods, arrowworms, jellyfish, fish larvae, and larval forms of
bottom-dwelling starfish, bristle worms, sea anemones, and mollusks—feed on
phytoplankton. Zooplankton in turn provide food for fish and squid, both of
which are abundant in Antarctic waters. Members of one group of fish known as
icefish have natural antifreeze to survive in the cold temperatures.
Concentrated swarms of zooplankton (especially of krill and young fish),
together with larger fish (especially of superfamily Notothenioidea) and squid,
provide food for the seals, whales, and seabirds that are Antarctica’s major
predators and most prominent animals. Some organisms grow to large size in the
cold waters, including giant marine isopods related to sow bugs, giant starfish,
and giant sea spiders.
Whales are plentiful in the Southern Ocean,
more so since commercial whaling ended in the 1960s. Baleen whales such as blue,
fin, sei, minke, humpback, and southern right whales feed mainly on krill and
small fish, which they filter from the water. Among toothed whales, sperm whales
and bottle-nosed whales feed mainly on fish and squid, which they catch in deep
water, while killer whales (orcas) and several species of dolphins feed mainly
on surface-living fish. Killer whales also prey on penguins and seals.
Several species of seals breed within the
Antarctic region. Weddell and leopard seals live closest to the continental
shore, while crabeater and Ross seals live mainly on pack ice. Elephant seals
(the largest species) and fur seals breed mainly on the warmer fringing
islands.
About 40 species of seabirds—including 7
species of penguins, 4 species of albatross, 20 species of petrels, as well as
cormorants, gulls, skuas, and terns—breed within the region, mainly on islands
and continental coasts. In summer, snowy petrels fly long distances over the ice
to breed in inland mountain ranges. Major populations of penguins are found
around Antarctica, including Adélie, emperor, chinstrap, and gentoo penguins.
Emperor penguins breed in winter on sea ice. Local warming in the Antarctic
Peninsula area is affecting some stocks of penguins by reducing sea ice in areas
in which they breed or feed.
Large marine animals played an important
role in attracting humans to Antarctica: Sealers and whalers contributed
substantially to the early exploration of the Southern Ocean and coastal
regions. Fur seals and southern elephant seals of the islands near the Antarctic
Convergence were hunted for skins and oil throughout the 19th century until
economically profitable stocks were depleted. Hunting of elephant seals
continued into the 1950s. From 1904 through the 1960s whalers hunted large
migratory whales (blue, fin, sei, humpback, and sperm whales) for oil in
Antarctic waters from whaling stations on several Antarctic islands and from
floating factory ships. Beginning in the 1960s concern that seals and whales
would be hunted to extinction prompted several measures to protect surviving
populations. (For more information, see the Management and Conservation of
Antarctica section of this article.)
G | Mineral Resources in Antarctica |
Although only about 1 percent of the
continent’s ice-free areas have been surveyed for minerals, evidence indicates
that Antarctica contains rich mineral deposits. The Transantarctic Mountains
contain huge deposits of coal as well as copper, lead, zinc, silver, tin, and
gold. The Prince Charles Mountains of East Antarctica are rich in iron ore; the
Antarctic Peninsula contains copper and molybdenum ores; and the Dufek Massif
includes ores of chromium, platinum, copper, and nickel. It is also believed
that deposits of petroleum and natural gas exist in the continental shelf
regions, such as the area under the Ross Sea. Although Antarctica has prospects
for mineral development, there are concerns about the potential environmental
and political impacts of this development. In 1991 the signatory nations of the
Antarctic Treaty agreed to a 50-year moratorium on commercial mining activity.
The only mineral resources currently used are sand, gravel, and crushed rocks
for constructing airstrips and building foundations at the scientific stations.
III | EXPLORATION OF ANTARCTICA |
Long before Antarctica was discovered,
medieval world maps showed a huge continent, Terra Australis, occupying more
than half of the Southern Hemisphere. From the late 15th century several voyages
dispelled beliefs about the continent’s vastness and its attachment to Africa,
South America, and Australia. Over the next two centuries explorers came upon
many of the islands within the present-day Antarctic region, including the South
Sandwich Islands, South Georgia, and the Kerguelen Islands. In 1773 British
navigator Captain James Cook traveled farther south than anyone before him,
reaching latitude 71°10’ south. He explored the edge of the pack ice and was the
first to cross the Antarctic Circle. Cook saw no land, but judged correctly that
the massive icebergs around him could have accumulated only on land nearby.
Cook’s expedition marked the beginning of scientific exploration of the southern
polar region.
In July 1819 a Russian naval expedition led
by Fabian Gottlieb von Bellingshausen complemented and enhanced Cook’s findings.
Bellingshausen charted South Georgia and the South Sandwich Islands, then edged
eastward along the pack ice, twice crossing the Antarctic Circle, until he was
stopped by ice cliffs. In the following year he returned south to the ice’s
edge, continuing eastward and pressing through pack ice very close to the
continental coast. Later he discovered Peter I Island and Alexander Island. Like
Cook, Bellingshausen sailed to within sight of Antarctica without the
satisfaction of positive discovery.
British naval officer Edward Bransfield
sighted part of the present-day Antarctic Peninsula in 1820. Sealers of many
nations, who had been exploring Antarctic and subantarctic (lying just
north of the Antarctic Convergence) islands and waters since Cook’s voyage, had
sighted the South Shetland Islands, other parts of the Antarctic Peninsula, and
the South Orkney Islands by the early 1820s. In 1823 British navigator James
Weddell explored the present-day Weddell Sea, setting a new farthest-south
record of latitude 74° south. Within the next 20 years sealers and whalers
explored present-day Enderby Land on the eastern continental coast, Graham Land
(now the northern part of the Antarctic Peninsula) and Adelaide Island off its
coast, and the Sabrina Coast of East Antarctica and the neighboring Balleny
Islands.
Between 1838 and 1843 three naval
scientific expeditions added substantially to knowledge about Antarctica’s
coastline. French explorer Jules Dumont d’Urville discovered a part of the
Antarctic Peninsula, which he named Terre Louis Philippe. He also discovered
neighboring islands, now known as D’Urville and Joinville islands, and part of
the East Antarctica coast, which he named Terre Adélie (Adélie Coast). American
explorer Charles Wilkes penetrated the pack ice to explore the ice coast of
present-day Wilkes Land. British explorer Sir James Clark Ross discovered the
Ross Sea, reaching a new record latitude of 78° south. Ross charted the volcanic
island and the massive ice shelf that now bear his name; he also discovered
present-day Victoria Land and located the south magnetic pole, which at that
time was positioned among Victoria Land’s mountains.
From the 1870s to the 1890s German,
Scottish, and Norwegian whalers explored the Antarctic Peninsula, discovering
Bismarck Strait and several other new channels and islands. On January 24, 1895,
Norwegian whaler Henryk John Bull made the first recorded landing on the
continent outside the Antarctic Peninsula, at Cape Adare near the Ross Sea. In
1904 Norwegian whaler Carl Anton Larsen established the first Antarctic whaling
station, on South Georgia.
In 1895 delegates to the Sixth
International Geographical Congress in London, England, declared that
exploration of the Antarctic region was the greatest geographical exploration
still to be undertaken, and urged that scientific discovery of Antarctica begin
before the close of the century. Within the next few years expeditions from six
European nations took the field. From 1897 to 1899 a Belgian expedition explored
the west coast of the Antarctic Peninsula by ship. The vessel became trapped for
more than 13 months in the pack ice of Bellingshausen Sea, involuntarily
becoming the first expedition to winter south of the Antarctic Circle. In 1899
members of a small British expedition led by Carsten Borchgrevink became the
first people to spend the winter on the continent, at Cape Adare. The larger and
more successful British National Antarctic Expedition (1901-1904), led by naval
officer Robert Falcon Scott, spent two winters in McMurdo Sound in the southern
Ross Sea, exploring inland, discovering the polar plateau, and making the first
attempt to reach the South Pole. Although Scott failed to reach the pole, he
achieved a new farthest-south record of 82°17’ south.
Several other European expeditions traveled
to Antarctica during this period. The German South Polar Expedition, which
lasted from 1901 to 1903, became caught in pack ice 80 km (50 mi) from the shore
of East Antarctica, wintering on board and freeing themselves the following
summer. The Swedish National Expedition from 1901 to 1904 set up a base on Snow
Hill Island on the eastern flank of the Antarctic Peninsula; despite losing
their ship in the pack ice, the crew explored the area north and south of the
island. The Scottish National Antarctic Expedition of 1902 to 1904 wintered on
the South Orkney Islands and explored the unknown east coast on the Weddell Sea.
The expedition’s meteorological observatory on Laurie Island, taken over by the
Argentine navy upon Scottish departure, has since provided Antarctica's longest
unbroken climatic record. Two French expeditions led by physician Jean-Baptiste
Charcot wintered in the peninsula area in 1903 and 1908, discovering the Loubet
Coast north of Adelaide Island and exploring south into Marguerite Bay and the
Bellingshausen Sea.
A | Race to the South Pole |
In 1908 British explorer Ernest
Shackleton, who had accompanied Scott on his earlier expedition, led a British
expedition expressly to reach the South Pole. Pioneering a route from McMurdo
Sound across the Ross Ice Shelf, and through the Transantarctic Mountains by way
of the Beardmore Glacier, he and three colleagues reached the polar plateau.
Lack of food forced the party to turn back within 179 km (111 mi) of the pole.
In addition to attaining a new farthest-south point, they returned from the
mountains with samples of coal. Due to the type of vegetation necessary for the
formation of coal, this finding confirmed that Antarctica had once been
semitropical. Other members of the same expedition, under William Edgeworth
David, reached the south magnetic pole in 1909.
In 1910 Scott returned to McMurdo Sound,
again to seek the pole. In October 1911 he and four companions left their base
on Ross Island and began traveling along Shackleton's route, hauling their
supplies on sleds. Scott’s party reached the pole on January 17, 1912, only to
find that Roald Amundsen, a Norwegian explorer with experience on both Arctic
and Antarctic expeditions, had reached the pole almost five weeks earlier. Scott
and his party died on the return journey. Two of the men were injured along the
route, and the rest died from starvation and exposure at a camp just short of
their supply station.
Amundsen originally sought the North
Pole, but when that was conquered in 1909 he set his sights on the South Pole.
He and his companions set out from the Bay of Whales on the Ross Ice Shelf near
Roosevelt Island just four days before Scott’s team began their journey.
Outmatching Scott's group in experience and technique and using efficient dog
teams, Amundsen’s group climbed a steeper, shorter glacier (now Amundsen
Glacier) to the plateau. They arrived at the pole on December 14, 1911, and
arrived safely back at their base the following month.
With the pole conquered, explorers began
to take on new challenges. In 1912 Australian scientist Douglas Mawson led the
Australian Antarctic Expedition to explore the coast of East Antarctica directly
south of Australia. An overland party explored the area now known as George V
Land, although two of Mawson’s companions died and Mawson returned to his base
barely alive. Shackleton returned in 1915, intending to cross the continent from
the Weddell Sea to the Ross Sea by way of the pole. But his ship never reached
the continent; it became trapped by the ice and sank ten months later.
Shackleton reached South Georgia in a lifeboat, and returned to rescue his
stranded men three months later.
B | Aerial Exploration of Antarctica |
Despite these numerous land and sea
expeditions, by 1920 explorers had surveyed only 5 percent of Antarctica.
Advances in aviation and aerial photography rapidly increased the rate of
exploration, and by 1940 most of the coast and several inland areas had been
sighted and named. Australian aviator Sir George Hubert Wilkins made the first
Antarctic flight in 1928, traveling 1,000 km (600 mi) from Deception Island
along the Antarctic Peninsula.
In 1929 American aviator Richard Evelyn
Byrd flew from the Bay of Whales on the Ross Ice Shelf to the South Pole and
back, taking aerial photographs of many square kilometers of Antarctica’s
interior. Byrd returned to the same area to conduct more aerial photographic
surveys between 1933 and 1935. Scientific sledging parties gathered scientific
data and astronomical fixes that supplemented Byrd’s aerial photography. Byrd’s
expeditions established that mountains and high plateau lay in every direction
behind the Ross Ice Shelf and that Antarctica was beyond doubt a single
continent.
Between 1929 and 1931 the British,
Australian, and New Zealand Antarctic Research Expedition (BANZARE) used
floatplanes to explore and photograph many kilometers of East Antarctica’s
coast. Between 1929 and 1934 Norwegian whaler Lars Christensen equipped his
expeditions with seaplanes, which flew over and photographed the remote island
of Bouvetoya and stretches of the Antarctic coast from Enderby Land to Coats
Land. In 1936 American explorer Lincoln Ellsworth crossed Antarctica by air,
flying from Dundee Island at the tip of the Antarctic Peninsula to the Bay of
Whales. In 1938 a German expedition flew over and photographed an extensive area
of East Antarctica now known as Queen Maud Land (Dronning Maud Land).
C | Land Claims in Antarctica |
In 1908 Britain revived long-standing
territorial claims, based on discovery, to South Georgia, the South Shetland,
South Orkney, and South Sandwich islands, as well as Graham Land, to justify the
control and taxation of whaling in those areas. In 1923 Britain claimed the Ross
Ice Shelf and adjacent coasts (now Ross Dependency) for similar reasons. In 1924
France claimed Adélie Land, a narrow sector of East Antarctica where Dumont
d'Urville had landed in 1840. In 1933 Britain claimed the sectors of East
Antarctica that BANZARE had explored as an Australian territory; this area was
formally declared the Australian Antarctic Territory in 1936. Spurred by the
possibility of a German claim, Norway in 1939 claimed the sector of East
Antarctica later called Queen Maud Land, along with Peter I Island and
Bouvetoya. When Britain set up wartime stations in the peninsular region in
1943, Argentina and Chile lodged rival claims to the sector. Because U.S. policy
for Antarctica states that all nations should have free access for peaceful
pursuits, the U.S. government did not support claims made by American explorers
and does not recognize any foreign territorial claims.
IV | MANAGEMENT AND CONSERVATION OF ANTARCTICA |
During the exploratory period of Antarctic
history, scientific research was less important than discovery. In 1939 the U.S.
Antarctic Service Expedition under Richard Byrd introduced the concept of
permanent stations with science as a major objective. Two stations, at Bay of
Whales and Stonington Island off the Antarctic Peninsula, opened in 1941, but
closed after a year when the United States entered World War II. In 1943 Britain
set up several permanent stations. Although the British stations were set up
primarily to assert sovereignty against Argentine and Chilean claims in the
maritime Antarctic, they were staffed by scientists.
Establishment of these early bases began the
era of scientific research that was closely coupled with political rivalry.
During this period Argentina, Australia, Chile, and France established permanent
national expeditions, both to maintain territorial claims and to conduct
scientific research. In 1946 the United States conducted Operation Highjump, the
largest Antarctic expedition to date, involving massive exploration by means of
ships, aircraft, and temporary land stations. This operation also gave U.S.
military forces experience in polar conditions, seen as a necessity should a
confrontation with Soviet troops occur in the Arctic region of the Union of
Soviet Socialist Republics (USSR). Against the backdrop of the Cold War, a
period of political tension between the Soviet Union and its associated nations
and Western countries allied with the United States, the USSR declared its right
to make an Antarctic territorial claim in 1950.
The International Geophysical Year (IGY), a
period of worldwide coordinated geophysical research from July 1957 to December
1958, proved a useful step toward resolving political disputes in Antarctica.
Twelve nations (Argentina, Australia, Belgium, the United Kingdom, Chile,
France, Japan, New Zealand, Norway, South Africa, the United States, and the
USSR) agreed to cooperate on scientific research in Antarctica. Starting a year
beforehand, survey parties established research stations on an unprecedented
scale. During the IGY more than 5,000 scientists and support staff served at 49
Antarctic stations. Projects included studies of a wide range of geophysical
topics such as upper atmosphere physics, meteorology, oceanography, glaciology,
seismology, and geology. The IGY led to the establishment in 1958 of the Special
(later Scientific) Committee on Antarctic Research (SCAR), a group designed to
coordinate additional research; SCAR continues in that same function today.
A | Antarctic Treaty |
The international cooperation and overall
success of the IGY led the governments of the 12 nations to develop the
Antarctic Treaty, an agreement to extend cooperation in Antarctica after the IGY
ended. Concluded in 1959, the treaty asserts that Antarctica be used only for
peaceful purposes; prohibits military measures, fortifications, and weapons
testing; and requires freedom of scientific investigation and scientific
cooperation to continue. It provides for exchanges of scientific personnel,
plans for scientific programs, and scientific observations and results. It also
provides for exchanges of observers, mutual inspection of stations and of ships
and aircraft that are loading or discharging cargoes or personnel, and meetings
of representatives to promote its objectives. The treaty prohibits nuclear
explosions and disposal of nuclear waste in the treaty area (south of latitude
60° south).
The treaty addressed long-standing
territorial conflicts of interest over Antarctica. It made no ruling on the
validity of existing claims by seven nations (Argentina, Australia, Britain,
Chile, France, New Zealand, and Norway), and particularly on the overlapping
claims of Argentina, Britain, and Chile. However, it forbids any new claims
while the treaty is in effect and states that no member nations are required to
recognize the claims of other nations. Although the United States and the USSR
reserved the right to lodge future claims of their own, the indefinite freeze on
territorial claims served to ease Cold War suspicions of each other’s activities
in Antarctica.
Starting primarily as a tentative exercise
in scientific cooperation, the treaty gradually assumed a larger management
role. The nations that signed the treaty became Antarctica’s governing body, the
Antarctic Treaty System (ATS). Other interested nations have joined the ATS over
the years. Those that take part in substantial scientific Antarctic research
join the treaty administration as consultative parties, or full voting members.
Other nations not engaged in substantial research but agreeing to abide by the
treaty join as nonconsultative parties. More than 45 states have signed the
treaty. Members of the ATS meet yearly to exchange information, discuss matters
of common interest, and agree on measures to further the principles and
objectives of the Antarctic Treaty.
B | Conservation Measures in Antarctica |
The ATS has drafted several significant
resolutions aimed at resource conservation and protection. The Agreed Measures
for the Conservation of Antarctic Fauna and Flora (1964) protects all life on
Antarctica from nonscientific or nonsubsistence killing. The Convention on the
Conservation of Antarctic Seals (1972) protects all seals south of the Antarctic
Circle through yearly catch limits, restricted sealing seasons, and a ban on the
killing of Ross and fur seals. The Conservation of Antarctic Marine Living
Resources (1980) manages commercial fisheries in the Southern Ocean by imposing
quotas and bans on particular species and fishing zones. The Protocol on
Environmental Protection, also known as the Madrid Protocol (1991), is a
comprehensive set of measures for regulating human activities and preserving the
environment of Antarctica.
Problems associated with commercial
fishing around Antarctica include mammals, birds, and invertebrates accidentally
caught during fishing operations or entangled in lost nets and gear. Overfishing
or illegal fishing have also been documented. Large-scale commercial harvesting
of krill could affect a major food source for many kinds of animals.
Whaling falls under the control not of the
ATS, but of the International Whaling Commission (IWC). Established in 1946 to
regulate the industry in all the world’s oceans, the IWC set progressively lower
limits on whaling throughout the 1970s. In 1994 the IWC established an Antarctic
whale sanctuary to protect primary feeding grounds. However, Japan continues to
conduct what it claims are scientific whale hunts in the region.
V | SCIENTIFIC RESEARCH IN ANTARCTICA |
The scientific study of Antarctica has taken
on new importance in monitoring and understanding the effects of global warming
and climate change. Changes in the movement and melting of ice sheets and
glaciers, along with changes in the growth and seasonal melting of sea ice,
affect climate and sea levels worldwide as well as altering conditions for
wildlife in the region. Determining the cause of such changes is complex,
however. Normal variations in climate, currents, and wind patterns may play a
major role independent of effects of higher levels of carbon dioxide and other
greenhouse gases in the atmosphere.
Warmer waters in the region could also affect
wildlife. High levels of ultraviolet light from holes in the protective ozone
layer may be harmful to marine life as well as to birds and mammals. Pollution
carried by winds and currents enters the food chain and has been detected in
wildlife in Antarctica.
Research projects to study changes in the
Antarctic include the International Polar Year (IPY) 2007/2008, conducted from
March 2007 to March 2009. The IPY involves thousands of scientists from more
than 60 nations in more than 200 projects focused on the Arctic and the
Antarctic. Topics of study include biology, geology, climatology, meteorology,
oceanography, and geophysics. Also ongoing is the Census of Antarctic Marine
Life (CAML). The CAML is part of the international Census of Marine Life (CoML),
a ten-year international initiative begun in 2000 to study life in the oceans.
Satellites in space regularly monitor and map Antarctica and the ocean waters
and ice around the continent.
In addition to such special projects,
scientists from dozens of nations at more than 40 stations participate in
year-round research on Antarctica. Most stations are located on rocky shores or
coastal ice slopes. A few stations sit farther inland on the ice cap, cut off
from the outside world except by radio. Small stations have up to a dozen
scientists and support staff, while larger stations may have two to three times
as many. The largest is McMurdo, which may accommodate several thousand visitors
in summer, including those on their way to inland stations or field camps. Life
at the smaller stations is simple, with comfortable living quarters and a family
atmosphere. Larger stations resemble hotels or barracks, with cafeteria meals
and fewer home comforts. The largest stations are effectively small towns, with
stores, cinemas, chapels, banks, offices, laboratories, garages, powerhouses,
airstrips, and hostels for residents and visitors.
Men far outnumber women in Antarctica.
Although some people spend one or two years there at a time, most visit just for
the summer months when good weather facilitates fieldwork. Many scientists who
work indoors in laboratories or offices, perhaps servicing self-recording
instruments or collecting data by radio from remote instruments, may hardly be
aware of the cold world outside. Field scientists who travel in small parties by
tractor or skidoo (motorized toboggan), surveying or collecting specimens
and camping for weeks on end, live and work much closer to the challenges of
Antarctica’s unique landscape and climate.
Scientists have studied extensively
Antarctica’s ice sheet and the land beneath it. Geologists and solid-earth
geophysicists conduct research in plate tectonics, the study of the plates of
the Earth’s crust. Antarctica is a valued source of fossils, which provide a
record of the breakup of the supercontinent Gondwanaland. Although most of
Antarctica is covered in ice, ancient rock is exposed in the parts of the
Transantarctic Mountains and on islands on the Antarctic Peninsula.
Paleontologists have found fossils of dinosaurs, marine reptiles, birds,
mammals, and other prehistoric animals as well as plant life that lived in
Antarctica when the climate was much more temperate, although sunlight was
absent or reduced for part of the winter.
Glaciologists measure the movement and the
layers of the ice sheet. They use satellites to plot the slow movement of the
ice surface. Ice cores drilled through the layers of the ice sheet have enabled
scientists to trace changes in the climate over a period of tens of thousands of
years. Scientists have put radio transmitters on icebergs to plot their
movement. Some countries have considered the possibility of towing icebergs to
arid regions as a source of fresh water.
Astronomers have installed telescopes in
Antarctica to take advantage of the long dark nights and clear atmosphere. In
addition to infrared and visible-light observatories, neutrino detectors have
been buried in ice to map the source of these elusive subatomic particles. The
converging magnetic force lines at the poles also increase the flux of cosmic
rays, which can be studied with instruments on high-altitude balloons.
Scientists also collect meteorites that have landed in the ice sheet, including
specimens from the Moon and from Mars.
Biologists study the microbial, plant, and
animal life of the Antarctic region. These scientists model the continent’s
relatively simple ecosystems, study responses of plants and animals to hostile
environments, and measure the impacts of people on the polar environment. Marine
biologists study the local marine food chains. Warmer ocean temperatures and
increased ultraviolet radiation could have major effects on marine life in the
Antarctic region.
The atmosphere above the continent provides
another important area of study. Antarctica provides important information for
climatologists modeling atmospheric circulation, or the constant flow of warm
air toward the poles and cold air toward the equator (see Meteorology:
Energy Flow and Global Circulation). Antarctica’s relatively unpolluted,
thin, and dry atmosphere allows scientists to study phenomena such as auroras
and transmission of radio waves. Most notably, these scientists study the levels
of ozone, the atmospheric gas that protects life on the Earth from the Sun’s
harmful ultraviolet radiation. In 1985 they identified the so-called ozone hole,
a region of depleted ozone that develops over Antarctica each spring and
virtually disappears several months later. Continuous monitoring revealed that
the size of the hole continued to increase.
Largely due to the work of Antarctic
scientists, many nations have reduced or eliminated the use of
chlorofluorocarbons (CFCs), which have been linked to ozone depletion. In 1987,
36 nations, including the United States, signed the Montréal Protocol, a treaty
to protect the ozone layer. In the 1990s further steps were taken to ban the
production of CFCs. Many scientists believe that the presence of CFCs in the
atmosphere peaked in 2001 and then began to decline. Nevertheless, U.S.
government scientists reported in 2006 that the ozone hole over Antarctica had
reached its greatest extent ever. They do not expect the ozone layer to recover
until 2065.
Finally, medical researchers study the
scientists and support staff living in Antarctica. Physicians have made
discoveries about the behavior of viruses in a cold, isolated environment.
Immunologists study the ability of expeditioners to resist infection.
Psychological and sleep studies are frequently conducted during the winter, when
the extreme climate and lack of visitors isolate workers from the outside
world.
VI | GROWING PUBLIC INTEREST IN ANTARCTICA |
Until the middle of the 20th century only
explorers and technical staff were the main visitors to Antarctica. With the
establishment of the first research stations the continent became the preserve
of scientists. More recently Antarctica has slipped into public awareness, both
as a wilderness in need of conservation and as a venue for tourism. The two
trends began together: Tourists from the 1960s onward drew attention to
accumulating garbage and abandoned buildings littering Antarctica—relics of
installations used and discarded by scientists. Motion pictures and other forms
of popular culture have made penguins in particular a symbol of endangered
wildlife in the Antarctic region.
In the 1970s and 1980s growing environmental
organizations such as Greenpeace and the World Wildlife Fund (WWF) effectively
organized public opinion against practices at the bases that impacted the
natural environment, such as construction near animal breeding grounds, improper
disposal of containers and chemical wastes, and open burning of garbage. Largely
as a result of public pressure, many stations cleaned up former dumping sites.
They also began disposing of waste by shipping it back to the countries
operating the bases. Environmental groups continue to oppose mining in
Antarctica and to press for high standards of environmental protection. Some
seek to have Antarctica managed as a world park, a status akin to a national
park in the United States. This would protect Antarctica from mining, military
activities, and permanent human settlement.
Tourism has grown slowly since its beginning
in 1958. Tens of thousands of tourists visit Antarctica annually between
November and March. Most travel by ship and only go ashore for brief periods, so
they require very few facilities on land. Several thousand more tourists take
sightseeing flights over the continent from countries in the southern
hemisphere. Although some environmental groups feel that an increase in tourism
would undoubtedly increase its impact, on its current scale tourism makes few
demands on the environment and does not interfere significantly with scientific
activities. In introducing nonscientists to the scenery, wildlife, and mystery
of Antarctica, tourism may well be helping broaden public interest in
Antarctica, thereby ensuring a safer future for this most remarkable area of the
world.
No comments:
Post a Comment