The Arctic

Map from Worldatlas.com

The Arctic consists of ocean surrounded by continental land masses and islands. The central Arctic Ocean is ice-covered year-round, and snow and ice are present on land for most of the year.

The southern limit of the arctic region is commonly placed at the Arctic Circle (latitude 66 degrees, 32 minutes North). The Arctic Circle is an imaginary line that marks the latitude above which the sun does not set on the day of the summer solstice (usually 21 June) and does not rise on the the day of the winter solstice (usually 21 December). North of this latitude, periods of continuous daylight or night last up to six months at the North Pole.

This region of the planet, north of the Arctic Circle, includes the Arctic Ocean, Greenland, Baffin Island, other smaller northern islands, and the far northern parts of Europe, Russia (Siberia), Alaska and Canada.

The Arctic is a vast, ice-covered ocean, surrounded by tree-less, frozen ground, that teems with life, including organisms living in the ice, fish and marine mammals, birds, land animals and human societies.

NSIDC Map

The Arctic consists of the Arctic Ocean, bordered by the northern parts of the mainlands of North American and Eurasia, and their outlying islands. Some of these islands are mountainous with interior icecaps, such as Greenland and the northern half of Novaya Zemlaya. Others are low-lying and not glaciated, such as Wrangel Island and the western islands of the Canadian Arctic.

The Arctic Circle is an imaginary line located at 66º, 30'N latitude, and as a guide defines the southernmost part of the Arctic. The climate within the Circle is very cold and much of the area is always covered with ice.

 In the mid winter months, the sun never rises and temperatures can easily reach lows of - 50º F in the higher latitudes. In the summer months (further south), 24 hours of sunlight a day melts the seas and topsoil, and is the main cause of icebergs breaking off from the frozen north and floating south, causing havoc in the shipping lanes of the north Atlantic.

The total number of species as well as biological productivity is lower than in more southern latitudes. Strong surface winds occur resulting in a severe wind-chill, and abundant drifting snow in winter. Instead of tree growth there is tundra vegetation that includes grasses, sedges, mosses, lichens, and shrubs...all low-standing plants that exist on permafrost soils that are frozen solid throughout most of the year.

In terms of marine life, because the waters of the Arctic are permanently covered with a layer of drifting pack ice, sunlight never deeply penetrates the surface waters to nourish and encourage biological growth. In addition, the water is vertically stable, offering no upwelling of inorganic salts (like phosphates, nitrates, and silicates,) without which a rich life in the upper sunlit layers cannot exist. The result is that the true marine Arctic remains cold and relatively lifeless. It is only near the land or in the Subarctic where the pack-ice is seasonal and the waters are warmer and richer in nutrients, that there is a proliferation of plant and animal life that encompasses the total spectrum of the food chain from microscopic phytoplankton to walruses and whales.

Siberia feels the heat of global warming Russia Today Video

The primary residents of the Arctic include the Eskimos (Inuits), Lapps and Russians with an overall population (of all peoples) exceeding two million. The indigenous Eskimos have lived in the area for over 9,000 years, and many have now given up much of their traditional hunting and fishing to work in the oil fields and the varied support villages. Some contemporary occupants of the Arctic and the areas they inhabit are shown on the map below.

The first explorers of the Arctic were Vikings. Norwegians visited the northern regions in the 9th century, and Eric the Red (Icelander) established a settlement in Greenland in 982.

Robert E. Peary

 The northernmost point on the earth's surface is the geographic North Pole, also known as true north. It's located at 90° North latitude and all lines of longitude converge at the pole. The earth's axis connects the north and south poles, as its the line around which the earth rotates. The North Pole is about 450 miles (725 km) north of Greenland in the middle of the Arctic Ocean - the sea there has a depth of 13,410 feet (4087 meters). In 1909, after numerous attempts by regional explorers, Robert E. Peary reached the North Pole.

A magnetic compass does not point toward the true North Pole of the Earth. Rather, it more closely points toward the North Magnetic Pole of the Earth. The North Magnetic Pole is currently located in northern Canada. It wanders in an elliptical path each day, and moves, on the average, more than forty meters northward each day. Evidence indicates that the North Magnetic Pole has wandered over much of the Earth's surface in the 4.5 billion years since the Earth formed. The Earth's magnetic field is created by Earth's partially ionized outer core, which rotates more rapidly than the Earth's surface. 

NASA JPL, University of Alaska - Fairbanks Satellite: RADARSAT

NASA: A Short Tour of the Cryosphere Video

Arctic Climate

The arctic climate is characterized by high spatial variability, and includes both polar maritime (influenced by the ocean) and continental (influenced by large land masses) climate subtypes. The main constant is that the climate in all arctic areas is affected by the extreme solar radiation conditions of high latitudes.

For example, the amount of solar radiation received in summer along the Siberian arctic coast compares favorably, by virtue of the long period of daylight, with that in lower middle latitudes. However, the low sun angle (elevation of the sun above the horizon) means that even minor topographic features, such as low hills, can cause major differences in climate at the local level by shading. Even though the Arctic receives a large amount of solar energy in summer, the high reflectivity (albedo) of snow and ice surfaces keeps absorption of solar energy low. Therefore, the heat gained during the long summer days is small and highly dependent on surface properties such as topography and albedo. For instance, wet tundra and bare ground (with low albedo) absorb more solar radiation than do high-albedo ice sheets. Similarly, wet snow absorbs more radiation than dry snow. Solar radiation is small or absent in winter.

The annual cycle of global radiation (brown line) and surface air temperature (blue line) at a grid cell location in the central Beaufort Sea. Values were drawn from the Arctic Meteorology and Climate Atlas grided fields for global radiation and two-meter air temperature.

Maritime climate conditions prevail over the Arctic Ocean, coastal Alaska, Iceland, northern Norway and adjoining parts of Russia. In these areas, winters are cold and stormy. Summers are cloudy but mild with mean temperatures about 10 degrees Celsius. Annual precipitation is generally between 60 cm and 125 cm, with a cool season maximum (largely snowfall) and about six months of snow cover.

The interior, continental climates have much more severe winters, although precipitation amounts are less. In these regions, permafrost (permanently frozen ground) is wide-spread and often of great depth. In summer, only the top one to two meters of ground thaw. Since the water cannot readily drain away, this "active layer" often remains waterlogged. Although frost may occur in any month, long summer days usually provide three months with mean temperatures above 10 degrees Celsius, and at some stations in the continental interiors temperatures can exceed 30 degrees Celsius.

In winter, arctic weather is dominated by the frequent occurrence of inversions (when warm air lies above a colder air layer near the surface). The inversion layer decouples the surface wind from the stronger upper layer wind. For this reason, surface wind speeds tend to be lower in winter than one might expect. In summer, inversions are less frequent and weaker, and arctic weather patterns are dominated by the movement of low pressure systems (cyclones) across Siberia and into the Arctic Basin.

In many arctic and subarctic regions, the weather is controlled by semipermanent low pressure systems that are weakly developed in summer, but stronger in winter. The most important of these low pressure systems are the Icelandic Low and the Aleutian Low. In winter, eastern Eurasia is dominated by the semipermanent Siberian High. High pressure is also prevalent over the Canadian Arctic Archipelago during the cold season.

NASA JPL Video: The Big Thaw October 01, 2007 A thick chunk of Arctic sea ice the size of two states has disappeared. Is it global warming or normal causes? A new NASA-led study found a 23-percent loss in the extent of the Arctic's thick, year-round sea ice cover during the past two winters. Between winter 2005 and winter 2007, the perennial ice shrunk by an area the size of Texas and California combined. This drastic reduction of perennial winter sea ice is the primary cause of the fastest-ever sea ice retreat on record this summer. Scientists say the rapid decline in winter perennial ice was caused by unusual winds. For more information go to: www.jpl.nasa.gov

Dramatic thinning of Arctic ice

NOAA Graphic

The Arctic is losing sea ice, impacting climate & weather farther South

Polar ice reflects light from the sun. As this ice begins to melt, less sunlight gets reflected into space. It is instead absorbed into the oceans and land, raising the overall temperature, and fueling further melting. This results in a positive feedback loop called ice albedo feedback, which causes the loss of the sea ice to be self-compounding. The more it disappears, the more likely it is to continue to disappear.

credit:NASA

In February, Arctic sea ice extent continued to track below the average, and near the levels observed for February 2007. Ice extent was unusually low in the Atlantic sector of the Arctic, and above normal in the Bering Sea. Meanwhile, Antarctic sea ice reached its summer minimum, near the average for 1979 to 2000.

Overview of conditions Arctic sea ice extent averaged for February 2010 was 14.58 million square kilometers (5.63 million square miles). This was 1.06 million square kilometers (409,000 square miles) below the 1979 to 2000 average for February, but 220,000 square kilometers (85,000 square miles) above the record low for the month, which occurred in February 2005. Ice extent was above normal in the Bering Sea, but remained below normal over much of the Atlantic sector of the Arctic, including the Barents Sea, part of the East Greenland Sea, and in the Davis Strait.

Conditions in context 

During February 2010, ice extent grew at an average of 25,700 square kilometers (9,900 square miles) per day. Sea ice extent increased at a fairly steady rate in the early part of the month and then slowed after the middle of February. Ice extent remained more than two standard deviations below the 1979 to 2000 average throughout the month.

February 2010 compared to past years 

The average ice extent for February 2010 was the fourth lowest February extent since the beginning of the modern satellite record. It was 220,000 square kilometers (85,000 square miles) higher than the record low for February, observed in 2005. The linear rate of decline for February is now 2.9% per decade.