A carbon offset is a financial instrument representing a reduction in greenhouse gas emissions. Although there are six primary categories of greenhouse gases, carbon offsets are measured in metric tons of carbon dioxide-equivalent (CO2e). One carbon offset represents the reduction of one metric ton of carbon dioxide, or its equivalent in other greenhouse gases.
There are two primary markets for carbon offsets. In the larger compliance market, companies, governments or other entities buy carbon offsets in order to comply with caps on the total amount of carbon dioxide they are allowed to emit. In 2006, about $5.5 billion of carbon offsets were purchased in the compliance market, representing about 1.6 billion metric tons of CO2e reductions.
In the much smaller voluntary market, individuals, companies, or governments purchase carbon offsets to mitigate their own greenhouse gas emissions from transportation, electricity use, and other sources. For example, an individual might purchase carbon offsets to compensate for the greenhouse gas emissions caused by personal air travel. In 2006, about $91 million of carbon offsets were purchased in the voluntary market, representing about 24 million metric tons of CO2e reductions.
Offsets are typically generated from emissions-reducing projects. The most common project type is renewable energy, such as wind farms, biomass energy, or hydroelectric dams. Other common project types include energy efficiency projects, the destruction of industrial pollutants or agricultural byproducts, destruction of landfill methane, and forestry projects. Purchase and withdrawal of emissions trading credits also occurs, which creates a connection between the voluntary and regulated carbon markets.
Carbon offsetting as part of a "carbon neutral" lifestyle has gained some appeal and momentum mainly among consumers in western countries who have become aware and concerned about the potentially negative environmental effects of energy-intensive lifestyles and economies. The Kyoto Protocol has sanctioned offsets as a way for governments and private companies to earn carbon credits which can be traded on a marketplace. The protocol established the Clean Development Mechanism (CDM), which validates and measures projects to ensure they produce authentic benefits and are genuinely "additional" activities that would not otherwise have been undertaken. Organizations that have difficulty meeting their emissions quota are able to offset by buying CDM-approved Certified Emissions Reductions. The CDM encourages projects that involve, for example, renewable energy production, changes in land use, and forestry, although not all trading countries allow their companies to buy all types of credit.
The commercial system has contributed to the increasing popularity of voluntary offsets among private individuals, companies, and organizations as well as investment in clean technologies, clean energy and reforestation projects around the world. Offsets may be cheaper or more convenient alternatives to reducing one's own fossil-fuel consumption. However, some critics object to carbon offsets, and question the benefits of certain types of offsets.
Carbon offsets have several common features:
The CDM identifies over 200 types of projects suitable for generating carbon offsets, which are grouped into broad categories. These project types include renewable energy, methane abatement, energy efficiency, reforestation and fuel switching.
Renewable Energy Credits (RECs) are also sometimes treated as carbon offsets, although the concepts are distinct. Whereas a carbon offset represents a reduction in greenhouse gas emissions, a REC represents a quantity of energy produced from renewable sources. To convert RECs into offsets, the clean energy must be translated into carbon reductions, typically by assuming that the clean energy is displacing an equivalent amount of conventionally produced electricity from the local grid. This is known as an indirect offset (because the reduction doesn't take place at the project site itself, but rather at an external site), and some controversy surrounds the question of whether they truly lead to "additional" emission reductions and who should get credit for any reductions that may occur.
An example of a project using a anaerobic digester can be found in Chile where in December 2000, the largest pork production company in Chile, initiated a voluntary process to implement advanced waste management systems (anaerobic and aerobic digestion of hog manure), in order to reduce greenhouse gas (GHG) emissions.
Industrial pollutants such as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) have a GWP many thousands of times greater than carbon dioxide by volume. Because these pollutants are easily captured and destroyed at their source, they present a large and low-cost source of carbon offsets. As a category, HFCs, PFCs, and N2O reductions represent 71% of offsets issued under the CDM.
Land use, land-use change and forestry (LULUCF) projects focus on natural carbon sinks such as forests and soil. Deforestation, particularly in Brazil, Indonesia and parts of Africa, account for about 20% of greenhouse gas emissions. Deforestation can be avoided either by paying directly for forest preservation, or by using offset funds to provide substitutes for forest-based products. For example, almost half of the world's people burn wood (or fiber or dung) for their cooking and heating needs. Fuel-efficient cook stoves can reduce fuel wood consumption by 30 to 50%, though the warming of the earth due to decreases in particulate matter (i.e. smoke) from such fuel-efficient stoves has not been addressed. There are a number of different types of LULUCF projects:
Once it has been accredited by the UNFCCC a carbon offset project can be used as carbon credit and linked with official emission trading schemes, such as the European Union Emission Trading Scheme or Kyoto Protocol, as Certified Emission Reductions. European emission allowances for the 2008-2012 second phase were selling for between 21 and 24 Euros per metric ton of CO2 as of July 2007.
The voluntary Chicago Climate Exchange also includes a carbon offset scheme that allows offset project developers to sell emissions reductions to CCX members who have voluntarily agreed to meet emissions reduction targets.
The Western Climate Initiative, a regional greenhouse gas reduction initiative by states and provinces along the western rim of North America, includes an offset scheme. Likewise, the Regional Greenhouse Gas Initiative, a similar program in the northeastern U.S., includes an offset program. A credit mechanism that uses offsets may be incorporated in proposed schemes such as the Australian Carbon Exchange.
Due to their indirect nature, many types of offset are difficult to verify. Some providers obtain independent certification that their offsets are accurately measured, to distance themselves from potentially fraudulent competitors. The credibility of the various certification providers is often questioned. Certified offsets may be purchased from commercial or non-profit organizations for US$1–30 per tonne of CO2, due to fluctuations of market price. Annual carbon dioxide emissions in developed countries range from 6 to 23 tons per capita.
Accounting systems differ on precisely what constitutes a valid offset for voluntary reduction systems and for mandatory reduction systems. However formal standards for quantification exist based on collaboration between emitters, regulators, environmentalists and project developers. These standards include the Voluntary Carbon Standard, Green-e Climate, Chicago Climate Exchange and the CDM Gold Standard, the latter of which expands upon the requirements for the Clean Development Mechanism of the Kyoto Protocol.
Accounting of offsets may address the following basic areas:
Carbon offset projects can also negatively affect quality of life. For example, people who earn their livelihoods from collecting firewood and selling it to households could become unemployed if firewood is no longer used. A paper from the Overseas Development Institute offers some indicators to be used in assessing the potential developmental impacts of voluntary carbon offset schemes:
Some activists disagree with the principle of carbon offsets, likening them to papal indulgences, a way for the guilty to pay for absolution rather than changing their behavior. For example, George Monbiot, an English environmentalist and writer, says that carbon offsets are an excuse for business as usual with regards to pollution. Proponents hold that the indulgence analogy is flawed because they claim carbon offsets actually reduce carbon emissions, changing the business as usual, and therefore address the root cause of climate change. Proponents of offsets claim that that third-party certified carbon offsets are leading to increased investment in renewable energy, energy efficiency, methane biodigesters and reforestation and avoided deforestation projects, the intended goal of carbon offsets.
Several certification standards exist, offering variations for measuring emissions baseline, reductions, additionality, and other key criteria. However, no single standard governs the industry, and some offset providers have been criticized on the grounds that carbon reduction claims are exaggerated or misleading. Problems include:
- Widespread instances of people and organizations buying worthless credits that do not yield any reductions in carbon emissions.
- Industrial companies profiting from doing very little – or from gaining carbon credits on the basis of efficiency gains from which they have already benefited substantially.
- Brokers providing services of questionable or no value.
- A shortage of verification, making it difficult for buyers to assess the true value of carbon credits.
Because offsets provide a revenue stream for the reduction of some types of pollutants, they can in some cases provide incentives to pollute more, so that polluting entities can later get credit for reducing emissions from an artificially high baseline. This is especially the case for offsets with a high profit margin. For example, one Chinese company generated $500 million in carbon offsets by installing a $5 million incinerator to destroy HFCs. The huge profits provide incentive to create new factories solely for the purpose of destroying the resultant pollutants and generating offsets. Not only is this outcome environmentally undesirable, it undermines other offset projects by causing offset prices to collapse.
Although many carbon offset projects tout their environmental co-benefits, some are accused of having negative secondary effects. Point Carbon has reported on an inconsistent approach with regards to some hydro-electric projects as carbon offsets; some countries in the EU are not allowing large projects into the EU ETS, because of their environmental impacts, even though they have been individually approved by the UNFCCC and World Commission on Dams..