2489: Bad Map Projection: The Greenland Special
|Bad Map Projection: The Greenland Special|
Title text: The projection for those who think the Mercator projection gives people a distorted idea of how big Greenland is, but a very accurate idea of how big it SHOULD be.
This is the fourth comic in the series of Bad Map Projections displaying Bad Map Projection #299: The Greenland Special. It came one and a half year after the third 2256: Bad Map Projection: South America (#358).
Map projections are different methods of representing the curved surface of the Earth on a two-dimensional map. There's no perfect way to do so. Because the Earth is not flat, any 2D map projection of it will always distort in a way the spherical reality, and a map projection that is useful for one aspect (like navigation, geographical shapes and masses visualization, etc.) will not be so for all the others. Typically a projection can represent only distances, areas or angles correctly, or at best imperfectly compromise two of these. The map choice should reflect the purpose you need to put it to, as it will necessarily distort (perhaps by twisting, skewing and/or resizing) those aspects it was not designed to show intact.
One such projection is the Mercator projection, which is designed so that all north-south lines of longitude are parallel to each other and all rhumb lines are consistent, which is most important in the time of map-based navigation. In reality, apart from the direct east-west directions, all the imaginary straight lines eventually meet at the poles which - even if they look parallel. The apparent distance between lines of latitude at the more extreme latitudes expands and the vicinity around each pole can never be drawn, as Mercator maps show geographic features plotted over ever larger map areas and distances than they should, for those nearer the poles, compared to those more equatorial. It is not possible to accurately compare the sizes of features across the globe using this projection, although the distortions can be effectively ignored for more local maps that do not plot a significant area of the globe (other than very close to the poles, historically not an issue) and along or between any given narrow strips of latitude away from the equator the comparison is between near equal scalings.
Greenland is a large island in the Arctic ocean and one of the nearest pieces of land to the north pole. The Mercator projection shows it to be significantly larger than it really is, compared to equator-straddling features such as Africa. It is therefore one of the most obvious inaccuracies of Mercator's map, if used (e.g.) in the classroom to teach physical geography (which perhaps would best use a representation that was consistent to area) rather than navigation.
The equal-area projections such as Mollweide or Tobler Hyperelliptical, the latter of which seems to extremely closely match the majority of the features evident upon the hand-drawn map, ensure that shapes contain the same relative proportion of area as they would upon the original spherical (or slightly spheroidal) surface, across all latitudes, but only by bending the directions and rescaling the distances ever more drastically the closer to the map edge (the anti-meridian to that the map is centred upon) you go. Unlike the Mercator projection, you can show the poles (as the extreme upper and lower limits of the rim) from an equatorially-centred view, and every point of the Earth is given one definite position (or two, where they lie exactly upon the crossing point between the left/right extremes of the map).
This comic's projection has retained this singular inaccuracy as a deliberate feature, though avoiding all other such inaccuracies of the Mercator projection by using a different projection elsewhere that is designed explicitly to avoid them. For example, a traditional Mercator map would show other polar areas such as Antarctica, southern South America, or even New Zealand as larger, but this map does not.
Although it may not be obvious, due to no land-masses being normally shown at/close-enough to the North Pole, the Mercatorish Greenland actually extends beyond the Elliptic map's northern limits into positions that do not even exist in reality - it does not even 'wrap around and over' the pole (like a bad toupée) but passes through it and the arbitrary back-edge meridian line and into purely imaginary space that does not exist upon the surface of the Earthly sphere. (For a flipped comparison, the lower 'curve' of Antarctica is not its coast, but merely the map's 'wrap-around' edge where a further step would have you stepping back onto the continent at a second point of this nominal edge. The true coast of Antarctica is only the rough upper edge, passing between the two points which each represent the one arbitrary 'wrap-around' coordinate that is opposite-but-adjacent on the map's oval edging, i.e. at ±180°E/W, but which otherwise has no particularly special quality 'on the ground'.)
The title text suggests that this map was created for people who believe Greenland should be larger. Whether these people believe it should be physically increased in size in some manner or should simply receive a greater share of the attention is unclear. One method for increasing its size would be to increase the coverage of its ice cap, which is currently decreasing in size due to increases in temperature. However, increasing Greenland's ice coverage to the size it appears on a Mercator map would involve covering the entire island and surrounding ocean with ice, which would be very problematic for Greenland's population.
- Bad Map Projection #299:
- The Greenland Special
- Equal-area map preserves size everywhere except Greenland, which uses the Mercator projection.
- [A drawn world map, perhaps the Tobler hyperelliptical projection, except for Greenland which is of a typical Mercator appearance and sized at almost the size of Africa, to almost entirely fill the space between Canada and Iceland. It extends up well beyond the nominal location of the North Pole, while its southern tip has an apparent latitude comparable to that of Spain or the vicinity of Virginia.]