Making sense of a BBC programme's carbon footprint

BBC One Planet's annual emissions as a tower of 10-tonne cubes (actual volume of gas). Embedding the volume in a photograph gives many more ways for viewers to put themselves in the space and relate to the volume.

The One Planet radio programme on the BBC's World Service came to Carbon Visuals with simple question: "what does our carbon footprint look like?"

One Planet was carefully accounting for emissions arising from the making of the programme and had arrived at a figure of about 34.9 tonnes per year. But what does that mean?

Measuring carbon dioxide in terms of mass (tonnes) makes sense from an accounting point of view but doesn't give us a sense of scale we can relate to. We examined a variety of alternative ways of representing One Planet's footprint.

We have shown the programme's annual emissions by volume in a recognisable location and in relation to an iconic feature - Trafalgar Square and Nelson's Column. These provide a sense of scale that enable the viewer to relate to the volume.

You can hear a discussion about this project, first broadcast on Thursday 8 April 2010, by visiting the One Planet website.

BBC One Planet's annual emissions as a tower of 10-tonne cubes (actual volume of gas). This representation is simpler than embedding an image in a photograph.

BBC One Planet's annual emissions as a pile of 1 tonne cubes of gas. Viewers are generally better at estimating number than estimating volume. Breaking a volume into unit parts can make it easier to relate to.

BBC One Planet's annual carbon footprint as a sphere of carbon dioxide gas. Spheres are not good when a viewer has to compare two different volumes, but they work quite well for visualising single quantities.

BBC One Planet's average daily carbon footprint (actual volume). The timescale chosen for emissions data can have a significant impact on how different audiences will make sense of it.

BBC One Planet's average emissions per second. Visualising rates of emission on very small timescales, as here, allows viewers to see the emissions as dynamic. Viewers can animate a still image like this for themselves - imagining spheres appearing rhythmically.