The
Arctic Ocean, located in the Northern
Hemisphere
and mostly in the Arctic
north
polar
region, is the smallest, and shallowest of the
world's five major oceanic divisions.
The
International
Hydrographic Organization (IHO) recognizes it as an ocean,
although some oceanographers call it
the Arctic Mediterranean Sea or simply the Arctic
Sea, classifying it as one of the mediterranean seas of the
Atlantic
Ocean
. Alternatively, the Arctic Ocean can be seen
as the northernmost lobe of the all-encompassing
World Ocean.
Almost completely surrounded by
Eurasia and
North America, the Arctic Ocean is
partly covered by
sea ice throughout the
year (and almost completely in winter). The Arctic Ocean's
temperature and
salinity
vary
seasonally as the
ice
cover melts and freezes; its salinity is the lowest on average of
the five major oceans, due to low
evaporation, heavy
freshwater inflow from
rivers and
streams, and limited
connection and outflow to surrounding oceanic waters with higher
salinities. The summer shrinking of the ice has been quoted at 50%.
The
National Snow and
Ice Data Center (NSIDC) use satellite data to provide a daily
record of Arctic sea ice cover and the rate of melting compared to
an average period and specific past years.

The Arctic Ocean
Geography
The Arctic
Ocean occupies a roughly circular basin and covers an area of about
, almost the size of Russia
. The
coastline is long.
It is surrounded by the land masses of
Eurasia, North America, Greenland
, and by several islands. It is generally taken to include Baffin Bay
, Barents
Sea
, Beaufort
Sea
, Chukchi
Sea
, East Siberian Sea
, Greenland
Sea
, Hudson
Bay
, Hudson
Strait
, Kara
Sea
, Laptev
Sea
, White
Sea
and other tributary bodies of water.
It is
connected to the Pacific
Ocean
by the Bering Strait
and to the Atlantic Ocean through the Greenland Sea
and Labrador
Sea
.
According to the
International
Hydrographic Organization, the limits of the Arctic Ocean
proper (that is, excluding the seas within the Ocean) are (see
the map):
- A
great circle line running from Cape Morris
Jesup
, the northernmost point of Greenland ( ) to the
northernmost point of Spitsbergen
(south of which line lies the Greenland
Sea).
- Parallel 80° North to North East Land
(Nordaustlandet
).
- The north shore of Nordaustlandet to its easternmost point,
Cape Leigh Smith ( ).
- A line
running from Cape Leigh Smith to Cape Kohlsaat
, the easternmost point of Franz Josef
Land
( , south of which line lies the Barents
Sea].
- A
line running from Cape Kohlsaat to Cape Molotov (Arctic Cape
), the northernmost point of Komsomolets
Island
( , south of which line lies the Kara
Sea).
- A
line running from Arctic Cape to the northernmost point of Kotelny
Island
( , south of which line lies the Laptev
Sea).
- A
line running from the northernmost point of Kotelny Island to the
northernmost point of Wrangel Island
( , south of which line lies the East Siberian
Sea).
- A
line running from the northernmost point of Wrangel Island to
Point
Barrow
, the northernmost point of Alaska
( , south of
which line lies the Chuckchi Sea).
- A
line running from Point Barrow to Cape Land's End on
Prince
Patrick Island
, Northwest Territories
( , south of which line lies the Beaufort
Sea).
- The northwest coast of Prince
Patrick Island north to Cape
Leopold M'Clintock, its northernmost point ( ).
- A
line running from Cape Leopold M'Clintock to Cape Murray on Brock Island
( ).
- The northwest coast of Brock Island north
to its northernmost point ( ).
- A
line running from the northernmost point of Brock Island to
Cape Mackay on Borden Island
, its westernmost point ( ).
- The northwest coast of Borden Island north to Cape Malloch ( , the northernmost point of the
Northwest Territories).
- A
line running from Cape Malloch to Cape
Isachsen on Ellef Ringnes Island
, Nunavut
, its northwestern most point ( ).
- A
line running from Cape Isachsen to the northwestern most point of
Meighen
Island
( ).
- A
line running from the northwestern most point of Meighen Island to
Cape Stallworthy on Axel Heiberg
Island
, its northernmost point ( ).
- A
line running from Cape Stallworthy to Cape
Colgate on Ellesmere
Island
, its westernmost point ( ).
- The
north coast of Ellesmere Island north to Cape Columbia
, its northernmost point ( ).
- A
line running from Cape Columbia to Cape Morris Jesup (south of
which line lies the Lincoln
Sea
).

Arctic region
An
underwater ridge, the
Lomonosov Ridge, divides the deep sea
North Polar Basin into two
oceanic basins: the
Eurasian Basin, which is between deep, and
the
Amerasian Basin (sometimes
called the North American, or Hyperborean Basin), which is about
deep. The
bathymetry of the ocean bottom
is marked by
fault-block ridges,
plains of the abyssal zone, ocean
deeps, and basins. The average depth of the Arctic Ocean is . The
deepest point is in the Eurasian Basin, at .
The two
major basins are further subdivided by ridges into the Canada Basin (between Alaska/Canada
and the
Alpha Ridge), Makarov Basin (between the Alpha and Lomonosov
Ridges), Fram Basin (between Lomonosov
and Gakkel ridges), and Nansen Basin (Amundsen Basin) (between the Gakkel Ridge and
the continental shelf that
includes the Franz Josef
Land
).
The Arctic Ocean contains a major
choke
point in the southern Chukchi Sea, which provides access to the
Pacific Ocean through the Bering Strait between Alaska and Eastern
Siberia. Subject to ice conditions, the Arctic Ocean provides the
shortest marine link between the extremes of eastern and western
Russia. There are several floating
research stations in the Arctic, operated
by the US and Russia.
The greatest
inflow of water
comes from the Atlantic by way of the
Norwegian Current, which then flows along
the Eurasian coast. Water also enters from the Pacific via the
Bering Strait. The
East Greenland
Current carries the major
outflow.
Ice covers most of the ocean surface year-round, causing
subfreezing air temperatures much of the time. The Arctic is a
major source of very
cold air that moves
toward the
equator, meeting with
warmer air in the middle
latitudes and causing
rain and
snow.
Marine life
abounds in open areas, especially the more southerly waters.
The
ocean's major ports are the cities of Murmansk
, Arkhangelsk
and Prudhoe Bay
.
The Arctic Ocean is encompassed by the
Arctic shelves, one of which, the
Siberian Shelf, is the largest on
Earth.
History
For much of
European history, the
North Polar regions remained largely unexplored and their
geography conjectural.
Pytheas of
Massilia
recorded an account of a journey northward in 325 BCE, to a land he
called "
Eschate Thule," where the
Sun only set for three hours each day and the
water was replaced by a congealed substance "on which one can
neither walk nor
sail." He was probably
describing loose sea ice known today as "
growler", or "bergy bits."
His "Thule" may have
been Iceland
, though Norway
is more
often suggested.
Early
cartographer were unsure whether
to draw the region around the North Pole as land (as in
Johannes Ruysch's
map of 1507, or
Gerardus Mercator's
map of
1595) or water (as with
Martin Waldseemüller's
world map of 1507).
The
fervent desire of European merchants for a
northern passage to "Cathay" (China
) caused
water to win out, and by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus
Septentrionalis" at the northern edge of their charts.
The few
expeditions to penetrate much beyond the Arctic Circle in this era added only small
islands, such as Novaya
Zemlya
(11th century) and Spitsbergen (1596), though since
these were often surrounded by pack-ice
their northern limits were not so clear. The makers of
navigational chart, more conservative
than some of the more fanciful cartographers, tended to leave the
region blank, with only fragments of known coastline sketched
in.
This lack of knowledge of what lay north of the shifting barrier of
ice gave rise to a number of conjectures. In England and other
European nations, the
myth of an "Open Polar
Sea" was persistent.
John
Barrow, long time Second Secretary of the British
Admiralty,
promoted
the exploration the region from 1818 to 1845 in search of this.
In the
United
States
in the 1850s and '60s, the explorers Elisha Kane and Isaac Israel Hayes both claimed to have
seen part of this elusive body of water. Even quite late in
the century, the eminent authority
Matthew Fontaine Maury included a
description of the Open Polar Sea in his textbook
The Physical
Geography of the Sea (1883). Nevertheless, as all the
explorer who travelled closer and closer to the
pole reported, the polar
ice cap is quite
thick, and persists year-round.
Fridtjof Nansen was the first to
make a
nautical crossing of the Arctic
Ocean, in 1896.
The first surface crossing of the ocean was
led by Wally Herbert in 1969, in a
dog sled expedition from Alaska to Svalbard
with air support.
Since 1937,
Soviet and
Russian manned drifting ice stations have extensively monitored
the Arctic Ocean.
Scientific
settlements were established on the drift ice and carried
thousands of kilometres by ice floes.
Climate
The images below compare the average late winter
and late summer polar ice pack of the
Arctic Ocean, averaged between the years 1978 and 2002, which
denotes variation in amounts of ice pack during these time
periods. |
Extent of the Arctic ice-pack during the month of February,
from 1978-2002.
|
Extent of the Arctic ice-pack during the month of September,
from 1978-2002
|
Under the influence of the
present
ice age, the ocean is contained in a
polar climate characterized by persistent cold
and relatively narrow annual
temperature ranges. Winters are
characterized by continuous
darkness
(
polar night), cold and stable weather
conditions, and clear skies; summers are characterized by
continuous
daylight (
midnight sun), damp and
foggy weather, and weak
cyclones
with rain or snow.
The temperature of the surface of the Arctic Ocean is fairly
constant, near the
freezing point of
seawater, slightly below . In the winter
the relatively warm ocean water exerts a moderating influence, even
when covered by ice.
This is one reason why the Arctic does not
experience the extremes of temperature seen on the Antarctic continent
.
There is considerable seasonal variation in how much pack ice of
the
Arctic ice pack covers the
Arctic Ocean. Much of the ocean is also covered in snow for about
10 months of the year. The maximum snow cover is in March or April
— about over the frozen ocean.
Climate has varied significantly in the past; as recently as 55
million years ago, during the
Paleocene–Eocene
Thermal Maximum the region reached an average annual
temperature of ; the surface waters of the northernmost Arctic
ocean warmed, seasonally at least, enough to support tropical
lifeforms requiring surface temperatures of over .
Natural resources
Petroleum and
natural gas field,
placer
deposits,
polymetallic nodules,
sand and
gravel aggregate,
fish,
seals and
whales can
all be found in abundance in the region.
The
political dead zone near the center of the sea is also the focus of
a mounting dispute between the United States, Russia, Canada,
Norway, and Denmark
. It is significant for the global
energy market because it may hold 25% or more
of the world's undiscovered oil and gas resources.
Natural hazards
Ice islands occasionally break away from
northern Ellesmere Island, and icebergs are formed from
glaciers in western Greenland and extreme
northeastern Canada.
Permafrost is found
on most islands. The ocean is virtually icelocked from October to
June, and
ships are subject to
superstructure icing from October to May. Before the
advent of modern
icebreakers, ships
sailing the Arctic Ocean risked being trapped or crushed by sea ice
(although the
Baychimo drifted
through the Arctic Ocean untended for
decades
despite these hazards).
Animal and plant life
Endangered marine species include
walruses
and
whales. The area has a fragile
ecosystem which is slow to change and slow to
recover from disruptions or damage.
The Arctic Ocean has relatively little plant life except for
phytoplankton. Phytoplankton are a
crucial part of the ocean and there are massive amounts of them in
the Arctic. Nutrients from rivers and the
currents of the Atlantic and Pacific oceans
provide food for the Arctic phytoplankton. During summer, the Sun
is out day and night, thus enabling the phytoplankton to
photosynthesize for long periods of time and
reproduce quickly. However, the reverse is true in winter where
they struggle to get enough light to survive.
Environmental concerns

Sea cover in the Arctic Ocean, showing
the median, 2005 and 2007 coverage

Decline of summer Arctic ice from
1979-2000 to 2002-05.
The polar ice pack is thinning, and in many years there will be
seasonal hole in the
ozone
layer.Reduction of the area of Arctic sea ice reduces the
planet's average
albedo, possibly resulting
in
global warming in a positive
feedback mechanism. Research shows that the Arctic may become ice
free for the first time in human history between 2013 and 2040.
Many scientists are presently concerned that warming temperatures
in the Arctic may cause large amounts of fresh
meltwater to enter the North Atlantic, possibly
disrupting global
ocean current
patterns. Potentially severe changes in the Earth's
climate might then ensue.
Other
environmental concerns relate
to the
radioactive
contamination of the Arctic Ocean from, for example, Russian
radioactive waste dump sites in
the Kara Sea and
Cold War nuclear test sites such as Novaya
Zemlya.
Major ports and harbors

Arctic Ocean ports
Some notable ports and harbours from west to east include:
- United States
- Canada
- Norway
- Russia
See also
References
Further reading
- Neatby, Leslie H., Discovery in Russian and Siberian
Waters 1973 ISBN 0-8214-0124-6
- Ray, L., and bacon, B., eds., The Arctic Ocean 1982
ISBN 0-333-31017-9
- Thorén, Ragnar V. A., Picture Atlas of the Arctic 1969
ISBN 0-8214-0124-6
External links