Its not just carbon in the form of carbon dioxide emitted when fossil fuels are burned that is counted. All emissions that add to the greenhouse effect and cause climate change are converted to their carbon dioxide equivalent and expressed in tonnes or kilograms of this gas (a footprint in tonnes may seem odd but that’s because the name is drawn from the ecological footprint). Gases converted to their carbon dioxide equivalent include methane, nitrogen oxides, various hydrocarbons.
Carbon emissions arise through fuel use for heating, lighting and transport. These are direct and we have reasonable control over them. Emissions also arise less directly because they are embedded in the products and services we use, from the production and disposal ends of their lifecycle. Its harder to have control over these though of course we can alter the type and number of products and services we consume.
Picture a system boundary around a city, a person, a house, factories, offices, a country, group of countries – the carbon footprint of each can be assessed. A boundary can be drawn around various products, say beef or cars, and the carbon footprint of the product’s lifecycle assessed. Organisations want to know their carbon footprint for energy and/or environmental management purposes, prioritising and quantifying effective, efficient and economic action. Growing numbers use the data in corporate social responsibility reports, responses to customer and investor requests. Organisations as diverse as Ipswich Town Football Club and Marks and Spencer have carbon neutral policies. Carbon footprint figures are appearing on a range of products, including Walkers crisps, Innocent Drinks smoothies and Boots shampoo…to enable informed consumer choices.
The carbon footprint concept is itself inevitably a simplification of reality. The computer models used to calculate footprints are further inevitable simplifications. This is both a plus and a minus of course. As with all measurement and calculation, care and preparation is needed when establishing and reporting figures. Independent verification may often be appropriate. Caution and checks are needed to ensure fair comparisons. Footprint standards are bringing methods closer together, making data more consistent and comparable.
Carbon footprints relate to one key environmental impact - climate change – and according to the Global Footprinting Network amount to half the ecological footprint (and not all types of environmental impact can be converted to the land area ecological footprints establish). This is a very significant proportion of the ecological footprint and so it is essential to establish it. However, we must not forget the other ways we are breaching environmental limits as measured by: overfishing; socio-economic effects; deforestation; species extinction; our water footprint; the spread of monocultures; deaths due to toxic pollution; quality of life reduction from noise and visual impacts, and more.
Sustainability is a whole system phenomenon. Types of impact are interrelated. If we don’t take a whole system approach to finding solutions our actions may be ineffective or cause further damage through effects we did not intend or anticipate. The dash for biofuels provides a timely lesson for us. Carbon footprinting is an excellent tool for awareness raising, getting a sense of the overall scale of the problem and progress made toward reduction targets but we must combine it with other measures and make good judgements on how problems interlink.