A carbon footprint is a "measure of the impact human activities have on the environment in terms of the amount of greenhouse gases produced, measured in units of carbon dioxide".[1] It is meant to be useful for individuals and organizations to conceptualize their personal (or organizational) impact in contributing to global warming. A conceptual tool in response to carbon footprints are carbon offsets, or the mitigation of carbon emissions through the development of alternative projects such as solar or wind energy or reforestation. A carbon footprint can be seen as a subset of earlier uses of the concept of ecological footprints, as said in the US.
Defining a carbon footprint
The carbon footprint is a measure of the exclusive global amount of carbon dioxide (CO
2) and other greenhouse gases emitted by a human activity or accumulated over the full life cycle of a product or service (see Wiedmann and Minx, 2008).
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.[2]
Normally, a carbon footprint is expressed as a CO
2 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. This definition underlies the personal carbon calculators. 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 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.[3]
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[4] and 5.05 g/kWh in 2002 for the Torness Nuclear Power Station.[5] 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.[6]
The Swedish utility Vattenfall did 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.[7]
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. [8]
Reducing a carbon footprint
The carbon footprint can be efficiently and effectively reduced by applying the following steps:
- Life Cycle Assessment (LCA) to accurately determine the current carbon footprint
- Identification of hot-spots in terms of energy consumption and associated CO
2-emissions - Optimisation of energy efficiency and, thus, reduction of CO
2-emissions and reduction of other GHG emissions contributed from production processes - Identification of solutions to neutralise the CO
2 emissions that cannot be eliminated by energy saving measures.
The last step includes carbon offsetting; investment in projects that aim at the reducing CO
2 emissions, for instance tree planting.
Kyoto Protocol, carbon offsetting, and certificates
Carbon dioxide emissions to air (and the emissions of other GHG's) are almost exclusively associated with the conversion of energy carriers like natural gas, crude oil, etc. The carbon content released during the energy conversion process reaches the atmosphere and is deemed to be responsible for the global warming process (i.e. climate change).
The Kyoto Protocol defines legally binding targets and timetables for cutting the greenhouse-gas emissions of industrialized countries that ratified the Kyoto Protocol. Accordingly, from an economic or market perspective, one has to distinguish between a mandatory market and a voluntary market. Typical for both markets is the trade with emission certificates:
- Certified Emission Reduction (CER)
- Emission Reduction Unit (ERU)
- Verified Emission Reduction (VER).
The mandatory market
To reach the goals defined in the Kyoto Protocol with least economical costs the following flexible mechanisms were introduced for the mandatory market:
- Emissions trading
- Clean Development (CDM)
- Joint Implementation (JI)
The voluntary market
In contrast to the strict rules set out for the mandatory market, the voluntary market provides companies with different options to acquire emissions reductions. A solution, comparable with those developed for the mandatory market, has been developed for the voluntary market, the Verified Emission Reductions (VER). This measure has the great advantage that the projects/activities are managed according to the quality standards set out for CDM/JI projects but the certificates provided are not registered by the governments of the host countries or the Executive Board of the UNO. As such, high quality VERs can be acquired at lower costs for the same project quality. However, at present VERs can not be used in the mandatory market.
The voluntary market in North America is divided between members of the Chicago Climate Exchange and the Over The Counter (OTC) market. The Chicago Climate Exchange is a voluntary yet legally binding cap-and-trade emission scheme whereby members commit to the capped emission reductions and must purchase allowances from other members or offset excess emissions. The OTC market does not involve a legally binding scheme and a wide array of buyers from the public and private spheres, as well as special events that want to go carbon neutral.
There are project developers, wholesalers, brokers, and retailers, as well as carbon funds, in the voluntary market. Some businesses and nonprofits in the voluntary market encompass more than just one of the activities listed above. A report by Ecosystem Marketplace shows that carbon offset prices increase as it moves along the supply chain——from project developer to retailer. [1].
While some mandatory emission reduction schemes exclude forest projects, these projects flourish in the voluntary markets. A major criticism concerns the imprecise nature of GHG sequestration quantification methodologies for forestry projects. However, others note the community co-benefits that forestry projects foster. Project types in the voluntary market range from avoided deforestation, afforestation/reforestation, industrial gas sequestration, increased energy efficiency, fuel switching, methane capture from coal plants and livestock, and even renewable energy. Renewable Energy Certificates (RECs) sold on the voluntary market are quite controversial due to additional concerns.[2]. Industrial Gas projects receive criticism because such projects only apply to large industrial plants that already have high fixed costs. Siphoning off industrial gas for sequestration is considered picking the low hanging fruit; which is why credits generated from industrial gas projects are the cheapest in the voluntary market.
The size and activity of the voluntary carbon market is difficult to measure. The most comprehensive report on the voluntary carbon markets to date was released by Ecosystem Marketplace and New Carbon Finance in July of 2007.[3].
Criticism of the term
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 vulcanism 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 action 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 climate change deniers and some 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, and Boots shampoos.
See also
- 2000 Watt society
- Carbon intensity
- Chief Green Officer
- Ecological footprint
- Ecosharing
- Energy Neutral Design
- Energy policy
- Global warming
- Green conventions, meetings & events
- Life cycle assessment
- List of countries by carbon dioxide emissions per capita
- List of countries by greenhouse gas emissions per capita
- Telecommuting
- Water footprint
- Weighted average cost of carbon
- Earthcheck
Notes
- ^ http://www.carbonfootprint.com Carbon Footprint LTD accessed Nov 10, 7:39am CST
- ^ http://www.isa-research.co.uk/docs/ISA-UK_Report_07-01_carbon_footprint.pdf
- ^ ClimateTalkReport_V7AB.indd
- ^ Vattenfall 2004, Forsmark EPD for 2002 and SwedPower LCA data 2005.
- ^ Energy Analysis of Power Systems accessed 20 October 2007
- ^ Electric Power Industry CO2 Emissions accessed 20 October 2007
- ^ nuclearinfo.net. Greenhouse Emissions of Nuclear Power
- ^ http://www.climatetalk.org.uk/downloads/CarbonCostofChristmas2007.pdf
References
- Parliamentary Office of Science and Technology POST (2006). Carbon footprint of electricity generation. October 2006, Number 268
- Wiedmann, T. and J. Minx (2008). A Definition of 'Carbon Footprint'. Ecological Economics Research Trends. C. C. Pertsova: Chapter 1, pp. 1-11. Nova Science Publishers, Inc, Hauppauge NY, USA. https://www.novapublishers.com/catalog/product_info.php?products_id=5999, also available as ISA-UK Research Report 07/01 from http://www.isa-research.co.uk/reports.html.
- World Energy Council Report (2004). Comparison of energy systems using life cycle assessment.
- Energetics (2007). The reality of carbon neutrality.
External links
- A Definition of Carbon Footprint: ISA-UK research report 07-01 A comprehensive review of definitions.
- Carbon Footprint information leaflet for private and public organisations
- Life Cycle Assessment, introduction
- Independent directory of service providers, databases, tools for LCA/Carbon footprint and related
- Low Impact Living household environmental impact calculator Calculates household carbon footprint and also water consumption, trash production, etc.