Using the website tool True Size of I learned about the distortions inherent in the web mercator projection. This projection stretches the area around the poles in order to present a 2D image making places such as Greenland appear much larger than they are.
This website allows you to move countries and states around the map while adjusted to show their true size in relation to areas of the map projection that are more acute, that is, those towards the equator. Countries near the equator are closer to their true size in this projection. For this exercise I moved three regions; Alaska, Greenland and Sweden to overlay with Brazil. These areas are all near the poles in the web mercator projection and appear larger than they are. When overlaid with Brazil you can see below that they all fit inside with room to spare!
Distortions are not just about scale but shape as well. I noticed especially the change in shape with Greenland in the image below which, when brought down to the equator to adjust for true size also shows a much "thinner" version of the country than we are used to seeing on these 2D maps. Distortions of size and scale are important o keep in mind because these visualizations affect our thought process about space and relationships which may negatively effect our ability to communicate knowledge with maps.
Aside from more obviously large or distorted nations and states, this also shows how distortions can be assumed about smaller areas. For example, seeing Iceland and Hawaii on the map with the understanding that locations near the poles appear larger, may lead you to assume that these two land masses are about the same in size. When we overlay using this tool however we can see that indeed Iceland is larger than several islands in the Hawaiian archipelago.
One question that this exercise brings up is, to what extent can we tolerate these distortions? A very simplified version of the answer is akin to related to the fact that it depends on what type of data we are using and what purpose the map in intended to serve. These factors will lead to adjustments in projection type and coordinate system.
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