139 thousand tonnes of carbon dioxide would fill a sphere 521 metres across. To most Londoners, '139 thousand tonnes of carbon dioxide' is not a very meaningful quantity. Illustrating it in the context of London landmarks allows viewers to make it meaningful for themselves.
The illustration is compelling not just because it is visual, but because we can relate to it on a physical level. Londoners - the primary audience - know what it is like to walk across Tower Bridge, or stand near to the BT Tower, and so can 'feel' how big 139 thousand tonnes really is.
Bristol's emissions need a Bristol landmark to allow viewers to make the quantity meaningful for themselves. Breaking the quantity up into one-tonne cubes helps the viewer to develop a sense of the scale involved. As viewers, we sometimes struggle to compare volumes, but we are very adept at comparing numbers of things.
If you brought it all together, the World's carbon dioxide would fill a cube 116.92 km high. When this picture was made (in 2007) there was 2,989 billion tonnes of carbon dioxide in the atmosphere. The picture shows the volume this amount of the gas would occupy at sea-level pressure and temperature.
The blue section is the 'natural' carbon dioxide - the quantity that the Earth has maintained for millions of years. It is vital for all life on Earth. The red section of the cube is the carbon dioxide we have added to the atmosphere (and is still there) since industrialisation began in about 1800.
The picture reveals how human activity can have a dramatic effect on climate. This relatively small amount of gas makes a huge difference to global temperatures. Increasing the amount will have a significant impact.
One tonne of carbon dioxide gas would fill a cube 8.13 metres high. This volume is illustrated in comparison with semi-detatched houses on a typical English suburban street.
Because we can relate to this illustration physically it provides a better sense of scale than the abstract number itself.
A modern 11W lightbulb is approximately as bright as a traditional 60W incandescent bulb but over 5 times as efficient, which means using modern bulbs uses less than a fifth of the electricity and so emits less than a fifth of the carbon dioxide.
The calculation of carbon dioxide emissions, based on average UK grid electricity carbon intensity, assumes that power delivered to an energy saving lightbulb is equivalent to that delivered to an incandescent lightbulb. In fact there is a subtle difference, which means the emissions from the energy saving bulb is an underestimate. Because energy saving bulbs have a power factor that is less than 1, more current flows along the transmission wires (see: en.wikipedia.org/wiki/Power_factor). This means that the transmission losses (energy lost as electricity is delivered to homes) are greater for an 11 Watt energy saving bulb than they would be for an 11 Watt incandescent bulb, and so a bit more carbon dioxide will be emitted. However, the transmission losses are a small percentage of the total load so the difference is small.
Energy saving bulbs significantly reduce carbon dioxide emissions.
Carbon Visuals were asked by a London Assembly member to provide visualisations to show the difference in emissions between ‘normal’ car and ‘gas guzzler’. It is planned to use the image in campaign and educational material in London.
This image, and the one below illustrate the potential for showing different kinds of transport emissions.
Carbon emissions data make more 'sense' to us if we can visualise the actual volumes of carbon dioxide in relation to the vehicle, ship or aircraft
Visualising emissions for short journey distances can work well in relation to the size of a person.