I read recently this article on the BBC News website. I thought the map they used (below) to show the areas of Britain with the largest domestic carbon footprints was a little uninspiring.

bbc_map_carbon

The colour scale was unclear with no explanation as to why the numbers jump around (the interval changes from 1 to 2) and appears to, for example, ignore the values that fall between 24 to 26 tonnes per household. Southern England is too red in the sense that it is hard to distinguish between areas with the highest emissions. I also feel that a more useful variable to plot is whether areas are increasing or decreasing their domestic carbon emissions. I understand why people are keen to highlight, for example, that David Cameron’s constituency is one of the top 40 most polluting, but it presents a static picture. It may be that he has heavily invested in household energy efficiency programs and dramatically reduced emissions compared to a few years ago- equally the constituency’s emissions could be increasing because he has avoided potentially unpopular environmental policies.

In response to my comments above I have logged on to the Guardian Data Blog to get hold of the UK Carbon Emissions by Local Authority Data they have published. In order to represent both total emissions and improvement between 2005 and 2007 I have generic for ciprodex otic suspension opted to use cartograms. The first cartogram focusses on the Local Authority (LA) by rescaling their boundaries by the total domestic carbon emissions. The colours represent the % reduction or increase in emissions between 2005 and 2007. So areas that have been expanded a lot and coloured red are large domestic emitters and getting worse, whereas shrunken blue areas are already low domestic emitters that are reducing emissions. I have used  Jenks’ Natural Breaks to decide the transitions from one colour to the next.

emissions_carto _small

This second cartogram is subtly different because the boundaries are scaled by the average per captia emissions for each LA. An enlarged area is one where the people living there are relatively high emitters of carbon dioxide. Their total contribution from the entire LA population (as shown in the cartogram above) can still however be small compared to other areas in the country. Equally a large LA can appear as a large emitter in the above map simply because more people live there even though they may have very low per capita emissions as shown below. As before the colours represent the % increase or decrease in carbon emissions between 2005 and 2007. I don’t think these maps are perfect by any means but they present a more eye-catching interpretation of an important but heavily discussed issue.

Per_capita_emissions_carto _small

6 Comments

  1. Anon

    Plotting the change is an improvement, but I have no idea which regions are the best and which are the worst because their shapes have changed so much in your new plots.

    The beauty of the BBC plot is that is clear and simple and shows the UK as we can all recongnise it. Yes, the scale needs changing and they could also have plotted the change, but otherwise the approach is fine. Its more like the BBC has been sloppy, rather than chosing the wrong type of map.

    1. James Author

      I can’t disagree that the cartograms have distorted some LAs to beyond recognition. I don’t think they make the LAs any less clear than the large areas of the same colour on the BBC map that makes it impossible to distinguish boundaries. In my opinion map viewers still have to look at their approximate area of the country and guess at where their area of interest is. By looking at both cartograms you can still see, for example, that London contributes the most carbon dioxide but the people who live there are actually pretty good at keeping their personal emissions down. Despite their limitations I think cartograms can provide a refreshing visualisation of important issues. This is done especially well by the University of Sheffield’s Worldmapper website.

  2. Mats Elfström

    Hi!
    The cartograms are very good and must be read as such, and I think the viewer understands the difference between these and ordinary maps.
    But a question arises: is it common practice to ignore the rest of Ireland on British maps? It took me a while to figure out what the blob sou-west of Scotland was.
    This seems as a case of ‘cognitive geography’, i e what is not on the map is not there.

    1. James Author

      Hi Mats,

      It is fairly common to exclude the Republic of Ireland from British (or in this case the United Kingdom) maps. This is because data are only provided at a national level and in this case the Republic of Ireland is not included in any national datasets because they have their own as a separate country. I could have included the rest of Ireland and coloured it white to symbolise the lack of data, but this approach is uncommon. BBC weather maps (see here), for example include the island of Ireland but will rarely label any places. Equally when I was in Ireland recently I saw a number of talks focussed on the Republic of Ireland that excluded Northern Ireland because the data were not available to them. You will also notice the Isle of Man is missing as well.

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