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Carbon Footprint

Everyone has a carbon footprint - it's your own personal measure of how much carbon dioxide you create and how much you contribute to climate change.

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The carbon footprint is a measure of the exclusive global amount of carbon dioxide (CO2) and other greenhouse gases emitted by a human activity or accumulated over the full life cycle of a product or service.

The life cycle concept of the carbon footprint means that it is all-encompassing and includes all possible causes that give rise to carbon emissions. In other words, all direct (on-site, internal) and indirect emissions (off-site, external, embodied, upstream, downstream) need to be taken into account.

Normally, a carbon footprint is expressed as a CO2 equivalent (usually in kilograms or tonnes), which accounts for the same global warming effects of different greenhouse gases (UK Parliamentary Office of Science and Technology Post, 2006). Carbon footprints can be calculated using a Life Cycle Assessment (LCA) method, or can be restricted to the immediately attributable emissions from energy use of fossil fuels.

An alternative definition of the carbon footprint is the total amount of carbon dioxide attributable to the actions of an individual (mainly through their energy use) over a period of one year. The term owes its origins to the idea that a footprint is what has been left behind as a result of the individual's activities.

Carbon footprints can either consider only as direct emissions (typically from energy used in the home and in transport, including travel by cars, airplanes, rail and other public transport), or can also include indirect emissions (including CO² emissions as a result of goods and services consumed). Bottom-up calculations sum attributable CO² emissions from individual actions; top-down calculations take total emissions from a country (or other high-level entity) and divide these emissions among the residents (or other participants in that entity).

Age-related carbon footprint

A number of studies have calculated the carbon footprint of organisations and nations. One UK (2007) study examined age-related carbon emissions based on expenditure and consumption. The study found that on average people aged 50-65 years have a higher carbon footprint compared to any other age group.
Individuals aged 50-55 years old have a carbon footprint of approximately 13.5 tonnes/capita per year compared to the UK average of 12 tonnes.

Carbon footprint by energy type

A life cycle analysis centered around the Swedish Forsmark Nuclear power Plant estimated carbon dioxide emissions at 3.10 g/kWh (grammes per Kilowatts/hour) and 5.05 g/kWh in 2002 for the Torness Nuclear Power Station This compares to 11 g/kWh for hydroelectric power, 950 g/kWh for installed coal, 900 g/kWh for oil and 600 g/kWh for natural gas generation in the United States in 1999.

The Vattenfall study found Nuclear, Hydro, and Wind to have far less greenhouse emissions than other sources represented.

The Swedish utility Vattenfall carried out a study of full life cycle emissions of Nuclear, Hydro, Coal, Gas, Solar Cell, Peat and Wind which the utility uses to produce electricity. The net result of the study was that nuclear power produced 3.3 grams of carbon dioxide per KW-Hr of produced power. This compares to 400 for natural gas and 700 for coal (according to this study). The study also concluded that nuclear power produced the smallest amount of CO² of any of their electricity sources.

Carbon footprint of Christmas

An analysis of the carbon footprint of Christmas in the UK shows that consumption of items such as food, travel, lighting and gifts at Christmas produces as much as 650 kg of carbon dioxide (CO²) emissions per person - equal to 5.5% of the UK annual carbon footprint.

Over Christmas, the average person could produce as much as:

• 26 kg of CO² from Christmas food
• 96 kg of CO² from Christmas Car travel
• 218 kg of CO² from extravagant lighting displays
• 310 kg of CO² on Christmas Shopping
• Christmas carbon emissions could be reduced by up to 60 per cent to about 250 kg.
  Reducing a carbon footprint

The carbon footprint can be efficiently and effectively reduced by applying the following steps:

• Life Style assessment (LCA) to accurately determine the current carbon footprint
• Identification of hot-spots in terms of energy consumption and associated CO² emissions
• Optimisation of energy efficiency and, thus, reduction of CO² emissions and reduction of other Green House Gas (GHG) emissions contributed by production processes
• Identification of solutions to neutralise the CO² emissions that cannot be eliminated by energy saving measures.

The last step includes carbon offsetting; investment in projects that aim at the reducing CO² emissions, for instance tree planting.

Criticism of the Carbon Footprint

Criticism of the concept of a carbon footprint is generally based on disagreement with one or more of the following assumptions usually underlying the calculation of a carbon footprint:

• That carbon emissions are a significant cause of global warming.
• That human activity is a significant cause of these emissions.
• That it is possible to attribute all or most emissions to particular individuals.
• That individual initiative is necessary because market forces or legislation will not be powerful and timely enough.
• That each individual should therefore calculate and attempt to reduce his share of carbon emissions.
• Sometimes, that each person should be given as a target an equal share of emissions, or some other share.

Criticisms derived from rejection of these assumptions may therefore include:

• That other causes, such as methane emissions, are more important.
• That human activity is not as significant a cause as natural processes such as volcanoes or solar radiation.
• That many emissions cannot reasonably be attributed to any individual. E.g. should emissions from commuting be attributed to commuters or consumers of what they produce?
• That market forces or political activity will correct human activity in sufficient time.
• That population growth invalidates the calculations,
• That one cannot limit everyone to equal emissions, for example those in urbanized societies may be unable to avoid some emissions, while less-developed countries may not have the technology to mitigate others.

In particular, many skeptics maintain that human contributions to global warming are negligible. Therefore, they argue, it is useless or even harmful to concentrate on individual contributions.

Other activities
A carbon label, which shows the carbon footprint embodied in a product in bringing it to the shelf, was introduced in the UK in March 2007 by the carbon Trust. Examples of products featuring their carbon footprint are Walkers Crisps, Innocent Drinks (chilled beverage and spring water), and Boots shampoos.

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