What does Antarctica include?
Defining the poles
It may seem self evident that Antarctica is the region within the Antarctic Circle and the Arctic is everything within the Arctic Circle. However, both polar regions tend to be defined differently for different purposes. The polar circles at 66°33’ demark little as the wide divergence between what one finds at that point in the north and south attests.
Biologists would argue that tree line better marks the beginning of the Arctic area although, as that’s a very wide transition line, a demarkation based on temperature is frequently used that effectively covers the same area. That is defined as the region where the average temperature for the warmest month is less than 10°C. Antarctica, too, has a defining natural boundary – the Antarctic Convergence.
Another option is to define Antarctica as the continent itself. However, the continent extends beyond the Antarctic Circle – especially the Antarctic Peninsula region – and nearly all the winter sea ice develops north of the Circle. In contrast, there is no Arctic continent, just frozen sea far to the north of the Arctic Circle, even in winter. At the Arctic Circle one finds farms and towns in Scandinavia – the tree line lies much farther north.
There is also an arbitrary legal definition of Antarctica. The Antarctic Treaty encompasses everything south of 60°S.