It is very much the term of the moment, especially following the report in February 2007 by the UN Intergovernmental Panel on Climate Change on the effect of human activities on the world’s climate. The term has received wider attention in the UK than in the US: newspaper articles here frequently tell readers how to reduce their carbon footprint by changing the way they live. Shortly after the report was published, the Bishop of London agreed not to fly for a year in order to reduce his footprint and to make the point that such profligate use of fossil fuels was selfish.
The term carbon footprint refers to the amount of carbon dioxide — a potent greenhouse gas — that is given off by an organisation or an individual burning fossil fuels. This doesn’t only include the obvious, such as car and plane travel, heating, cooking and the like, but also covers the cost in fossil fuel of creating and transporting every item that we use or consume, including such necessities as food and clothing (another term also used is embodied energy). The carbon footprint, measured in tonnes, is taken to be a measure of the extent to which such activities contribute to global warming.
Footprint here is perhaps not the best term. It has been used figuratively for several decades to express an area over which an effect is felt, such as noise footprint, or the area within which a radio or television signal can be received, or the area that a piece of equipment covers, say on your desk. But its direct inspiration was ecological footprint, which seeks to measure the resource needs of a population by calculating the area of land needed to support it. This footprint is a further abstraction, being the metaphorical mark or imprint on the planet left by our carbon-dioxide-emitting activities.
Twenty ways YOU can cut your carbon footprint; After the hottest January for 90 years, how to reduce the global impact of your CO2 emissions.
Evening Standard, 1 Feb. 2007
At issue is an ongoing story in Britain about the prince’s “carbon footprint” — the amount of greenhouse gases generated by his travel in private planes and other activities — and Charles’ stated efforts to reduce it, including canceling a recent skiing trip.
Philadelphia Inquirer, 28 Jan. 2007