Several problems exist in accurately quantifying the greenhouse gases (GHG) which result from the production, transportation, usage, and recycling of products. We review in this paper the current attempts at measuring GHG emissions and investigate the potential of UbiComp technologies in improving the state of the art in carbon footprint calculation and in communicating the result to consumers. This has potential benefits on consumer awareness and behaviour and can also foster competition among companies towards higher energy and resource efficiency.