Read an Excerpt
The Arctic regions form a different environment, well recognizable among the other lands on the planet. Anyone who has been on really high mountains will have an approximate idea: cold, ice and sparse vegetation are characteristics of both these environments.
But there the analogy ends.
What distinguishes the Arctic is its colossal size and the sea, a half-frozen ocean that extends for more than 10 million square miles, surrounded by the desolate tundra of Eurasia and North America, which covers fully 3 million square miles, one tenth of the Earth's surface.
The Arctic's distinguishing characteristics can be briefly summarized as follows:
1) high latitudes;
2) long winters and short, cool summers;
3) low precipitation;
5) frozen lakes and seas;
6) the absence of trees (a plant is conventionally defined as a tree when its trunk emerges from the snow cover).
It is not easy to establish the boundaries of Arctic regions. If we consider one of the above criteria, the Arctic could be defined as the land above the Arctic Circle, the parallel of latitude at 66� 33' 03" north, which borders the territories where the sun never sets for at least one day in the summer.
This boundary, however, is not absolute as, due to refraction phenomena caused by the density of air on the horizon, the sun may appear at midnight even a couple of degrees below this latitude.
In any event, if we use the Arctic Circle as a reference, several anomalies immediately appear to undermine its validity.
The most glaring example is Hudson Bay, which freezes over completely in winter (and is home to numerous polar bears and seals), yet its southerntip is at a latitude of 55� north, whereas the Norwegian coast at sea level at a latitude of 71� north is certainly not considered Arctic, due to the important influence of the Gulf Stream.
Another definition of the extent of the Arctic comes from the Russian scientist Koeppen, who uses the isotherm for the month of July, the warmest month in the year, as a reference, taking the temperature of +10�C as indicative. The line obtained by connecting all points with this temperature includes what can be considered the Arctic.
Among other things, this line coincides almost perfectly with the timberline, and in fact the timberline has been suggested as the boundary between the Arctic and sub-arctic regions. In this case as well, the line of demarcation must be considered with caution; there are many treeless areas in Iceland, in the Aleutian Islands and in the northern part of Scotland which cannot be considered polar because the isotherm of +10�C is much farther north than they are.
Many factors other than temperature influence the timberline: the slope of the land, exposure to northerly winds, the duration of the snow cover, and the humidity of the soil. Recently and nearly contemporaneously, American and Russian scientists have highlighted a biological factor which had previously been unknown: the trees at the edge of the tundra produce few seeds (they produce fruit only once every ten years), and the seeds are also of poor quality.
In addition, they are prevented from sprouting by the layer of moss and predation by seed-eating birds.
On the other hand, the timberline may advance by about a mile or so when micro-climatic conditions, small valleys sheltered from the winds, rivers (so-called "gallery forests"), or large masses of water make temperatures locally less harsh. Moreover, the line of demarcation between the tundra and the taiga, which is the tree-covered area of the North, is a good biological boundary.
Almost all animals respect it, living either above or below this boundary. Arctic animals live in the tundra and seldom enter the forest, whereas sub-arctic animals are typical woodland creatures who live in the forests all year round. Very few animals migrate to the tundra in spring and return to the forest in autumn. During the last decades, many other definitions have been proposed to establish the Arctic boundaries, but they have all proved inadequate because of the many exceptions to the rule. At present the accepted division between the Arctic and the sub-arctic essentially uses the parameters set in the past, adjusting them only in accordance with the more accurate scientific discoveries made after the Second World War.
The following division is valid for the tundra, with the exception of the marine polar cap and Greenland's inland ice: the average temperature for the warmest month must be under 10�C and above 0�C, winters must always be long and cold, summers short and cool, with a possible freeze at any time of the year; the sub-soil must be permanently frozen, precipitation must be under 100 inches a year, and vegetation must consist of low shrubs, sedges, mosses and lichens.
A discussion of Arctic boundaries would not be complete without a brief word about marine boundaries.
While in the past the boundary of the Arctic was considered the line of maximum extension of the winter ice-pack, this definition has now been abandoned, and experts prefer to define polar waters on the ground of their physical properties, temperature and salt content. In brief, superficial Arctic waters extend from the polar sea and penetrate the Canadian archipelago, reaching the Beaufort Sea.
Most of these waters head south, touching the eastern coast of Greenland and coming back up the western coast for about 310 miles.
A secondary current descends from Baffin Bay, skirting Labrador and Newfoundland.
Finally, a glacial current flows down from the Bering Strait and skirts the Chukchi Peninsula and Kamchatka.
The distinguishing features of Arctic waters are low salinity, less than 34 per thousand, due to the rivers that dump their waters into the Arctic ocean, and temperatures below -1�C. Alongside the currents described above, which run from North to South, warmer, saltier currents flow from South to North, with salinity of over 35 per thousand and temperatures above freezing. Among these, the most important is the North Atlantic current, more commonly known as the Gulf Stream, which influences not only the Svalbard Islands, but also the coast of Norway, passing the Kola Peninsula (where the port of Murmansk is ice-free all year round), and finally reaching Novaya Zemlya. This means even the Arctic's marine boundaries cannot be determined in precise detail.
Oceanographers, however, trace a line that separates arctic from sub-arctic waters according to salinity and temperature. The study of different ocean currents and the calculation of their flow provided a more reliable line of demarcation.