What would a map of carbon dioxide emissions by country look like? Normally this map would have tones of the same color representing emissions. It might also have a piece of text explicitly stating the emission for each country. Another way to represent this is with a cartogram, a map that uses an attribute of the mapping unit for area instead of the physical land area. For carbon dioxide emissions, those countries with higher levels of emission would look physically bigger.
The Gapminder website contains public data for cumulative carbon dioxide emissions since 1751 and the total emissions for each year. When plotted on a cartogram it is a simple matter to see where emissions are coming from. This map was generated in ArcGIS software using a custom cartogram toolset.
Which countries have the greatest cumulative emissions? What about regions, such as Western Europe? Which nations had the highest emissions in 2004?
As you can see, cartograms are a good way of producing bivariate maps. Yet, what if we want to see this change over time? Click play here to see how this is done on the Gapminder website.