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 Changes In The Arctic

Dramatic changes have been occurring in the Arctic during the past decade. The change in the Arctic may play a substantial role in climate change throughout the globe. These changes include unusual melting of glaciers, sea ice, and permafrost, and shifts in patterns of rain and snow fall, freshwater runoff, and forest/tundra growth. The consequences include disrupted wildlife migration patterns, altered fish stocks, modified agricultural zones, and increased forest fires. These changes have impacted the lives of Native residents who depend on the environment for a continuation of their traditional subsistence lifestyle, and may also have significant impacts on the oil industry, tourism, and shipping routes. The change in the Arctic may play a substantial role in climate change throughout the globe.

National Snow and Ice Data Center Image

Climate data show that winter temperatures in the northernmost regions of the world have warmed alarmingly in a very short period. Parts of Alaska and northern Eurasia, for example, have warmed by nearly 11 degrees Fahrenheit in the winter months over the past 30 years. Climate evidence from the past four centuries gleaned from ice cores, lake cores, and tree rings indicates a gentler warming trend that extends back 400 years. This image shows the winter temperature trend in the Arctic from 1966 to 1995. The scale is in degrees Celsius per decade. Over the 20-year period shown, average winter temperatures in central Siberia warmed by as much as 4°C.

Surface air temperature anomaly for Barrow, Alaska in April and for Tromso, Norway in Winter. An anomaly is the difference from a long term average value for the same season. For Barrow, note the temperatures from 1990 onward are often more than 4 degrees above historical values. For Tromso, note the continuation of warm temperatures in the 1990's following a period of cold temperatures in the late 1970's and 1980's.

Dramatic thinning of Arctic ice

NOAA Graphic

In September of 2007, Arctic sea ice extent shrank to the lowest ever seen during the satellite record. The animation shows extent and concentration from 1979 to 2000; the magenta line indicates the median sea ice extent.

The National Snow and Ice Data Center (NSIDC) Graphic

 

Change in the age of ice on the Arctic Ocean, compared for September and based on results from a simulation using drifting buoy data and satellite-derived ice concentration data (Rigor and Wallace, 2004). Open water (OW) is shown in dark blue, and the oldest ice is shown in white. The darker green line marks 90% ice concentration, and the lighter green lines mark ice concentrations of 80, 70, 60, and 50%. This sequence shows that (a) most of the Arctic Ocean was covered by older, thicker sea ice in September 1988; (b) coincident with a transition to high-AO conditions in 1989 (Fig. 5), most of the older, thicker sea ice was rapidly flushed out of the Arctic Ocean through Fram Strait, so that by 1990 only 30% of the Arctic Ocean was covered by older, thicker sea ice; (c) the relative distribution between older, thicker and younger, thinner sea ice persisted during the 1990s, in spite of a shift back towards a more neutral AO in the mid-1990s; and d) the average ice age over the Arctic Ocean apparently continued to decrease through 2005, with older, thicker ice now limited to the area north of the Canadian Archipelago.-NOAA 2006 State of the Arctic

 

Sea ice extent in September 2005. From NSIDC.		Sea ice extent in September 2002. From NSIDC.

 

Satellites have mapped the extent of Arctic Sea since 1979. In the past decade the area of ice during September (annual minimum) has declined from over 6 million square kilometers to a record low of 4.3 million square kilometers in 2007. (NASA maps by Jesse Allen and Robert Simmon, based on data from the National Snow and Ice Data Center.)