The Carbon Trust's Pac-Man-like label (designed with consultants Brandsmiths) may be minimalist but the methodology is not. Based on the Trust's appraisal of companies seeking to cut greenhouse gases, it examines almost every aspect of a product's lifecycle along the supply chain to identify processes that cause emissions.

This means everything involved in farming, including, for example, crop-spraying or mining of different raw materials; the energy (and its source) used to convert them; the disposal or recycling of the waste generated; transport to the factory; the production process through packaging, storage and distribution; and, finally, the disposal or recycling of packaging.

The resulting data is then translated into estimates of all gases produced, which is expressed in grams of CO2 per gram of product. This figure indicates the product's source-to-store carbon footprint, which is shown on the right hand side of the label.

The label does have its limitations. There is nothing to indicate whether it is a high or low 'score' relative to similar, or indeed, any products.

Neither does it make clear that those who have signed up to the scheme have committed to a 'reduce or lose' policy, whereby failure to reduce the carbon footprint of a product over a two-year period results in the label being withdrawn. These issues will have to be addressed in advertising.