6 Defining the Arctic and Antarctic
You have seen how cold the polar regions can be (Figure 2) but how do you define what is meant by the terms ‘Arctic’ and ‘Antarctic’? The way this is done is extremely important for managing these areas. For example, one can hardly propose to save ‘Arctic wildlife’ unless you know where the Arctic begins and where for example it turns into northern Europe. Could the Arctic Circle be a useful definition for the Arctic?
At what latitude is the Arctic Circle?
The Arctic Circle is at the latitude 66.6° N.
Consider the Shetland Islands north of the British mainland. The islands are at approximately 60° N, 1° W (you can locate them on, for example, Figure 7a). In the Shetland Islands, the mean temperature, even in the coldest month of the year, is above ~5 °C and there are no glaciers.
From Figure 7a what latitude is the most southerly tip of Greenland?
The southern tip of Greenland just touches the 60° N grid line, therefore it is at ~60° N.
The southern tip of Greenland is called Cape Farewell and for seven months of the year the mean temperature is below 0 °C.
On the basis of the text in Section 5, in no more than 100 words explain why Cape Farewell would be expected to receive roughly the same amount of solar energy as the Shetland Islands over the course of a year.
Both Cape Farewell and the Shetland Islands are the same distance from the Equator at ~60° N (Figure 7a). Because they are both in the Northern Hemisphere and both at the same latitude, over the course of a year (from Figure 11), they could be expected to receive a similar amount of solar energy.
The two locations in the Northern Hemisphere and at the same latitude 700 km south of the Arctic Circle have quite a different climate. Greenland, which has the largest icecap in the Northern Hemisphere, is by any definition Arctic, but the Shetland Islands are not. Clearly, a particular latitude is not adequate to define the Arctic.
One island in the Southern Hemisphere is South Georgia, which is located in the South Atlantic Ocean at 54° S, 36° W.
Box 2 gave a latitude for London, England. Would you expect South Georgia to have a similar climate to England?
Because South Georgia is at a similar latitude to London it would be expected to receive roughly the same amount of solar energy over the course of a year. On this basis, all other things being equal, it is not unreasonable to assume they would have a similar climate.
Figure 13 shows the coastline of South Georgia and almost 60% of the island is covered by glaciers! But there are no glaciers in the UK. So choosing a latitude to define both polar regions does not seem to make sense. Another simple method could be to use the habitats of particular animals. For example, you could say that ‘Antarctica is where penguins live’, but there is a species of penguin found nesting on the coast of southern Africa and even a penguin species in the Galapagos Islands near the Equator! So that doesn’t work either.