A central authority (usually a government or international body) sets a limit or cap on the amount of a pollutant that can be emitted. Companies or other groups are issued emission permits and are required to hold an equivalent number of allowances (or credits) which represent the right to emit a specific amount. The total amount of allowances and credits cannot exceed the cap, limiting total emissions to that level. Companies that need to increase their emissions must buy credits from those who pollute less. The transfer of allowances is referred to as a trade. In effect, the buyer is paying a charge for polluting, while the seller is being rewarded for having reduced emissions by more than was needed. Thus, in theory, those that can easily reduce emissions most cheaply will do so, achieving the pollution reduction at the lowest possible cost to society.
There are active trading programs in several pollutants. For greenhouse gases the largest is the European Union Emission Trading Scheme. In the United States there is a national market to reduce acid rain and several regional markets in nitrous oxide. Markets for other pollutants tend to be smaller and more localized.
Carbon trading is sometimes seen as a better approach than a direct carbon tax or direct regulation. By solely aiming at the cap it avoids the consequences and compromises that often accompany those other methods. It can be cheaper, and politically preferable for existing industries because the initial allocation of allowances is often allocated with a grandfathering provision where rights are issued in proportion to historical emissions. In addition, most of the money in the system is spent on environmental activities, and the investment directed at sustainable projects that earn credits in the developing world can contribute to the Millennium Development Goals. Critics of emissions trading point to problems of complexity, monitoring, enforcement, and sometimes dispute the initial allocation methods and cap.
Because emissions trading uses markets to determine how to deal with the problem of pollution, it is often touted as an example of effective free market environmentalism. While the cap is usually set by a political process, individual companies are free to choose how or if they will reduce their emissions. In theory, firms will choose the least-costly way to comply with the pollution regulation, creating incentives that reduce the cost of achieving a pollution reduction goal.
Consider two European countries, namely Germany and Sweden. Each can either reduce all the required amount of emissions by itself or it can choose to buy or sell in the market.
For this example let us assume that Germany can abate its CO2 at a much cheaper cost than Sweden, e.g. MACS > MACG where the MAC curve of Sweden is steeper (higher slope) than that of Germany, and RReq is the total amount of emissions that need to be reduced by a country.
On the left side of the graph is the MAC curve for Germany. RReq is the amount of required reductions for Germany, but at RReq the MACG curve has not intersected the market allowance price of CO2 (market allowance price = P = λ). Thus, given the market price of CO2 allowances, Germany has potential to profit if it abates more emissions than required.
On the right side is the MAC curve for Sweden. RReq is the amount of required reductions for Sweden, but the MACS curve already intersects the market price of CO2 allowances before RReq has been reached. Thus, given the market allowance price of CO2, Sweden has potential to profit if it abates fewer emissions than required internally, and instead abates them elsewhere.
In this example Sweden would abate emissions until its MACS intersects with P (at R*), but this would only reduce a fraction of Sweden’s total required abatement. After that it could buy emissions credits from Germany for the price 'P' (per unit). The internal cost of Sweden’s own abatement, combined with the credits it buys in the market from Germany, adds up to the total required reductions (RReq) for Sweden. Thus Sweden can also profit from buying credits in the market (Δ d-e-f). This represents the ‘Gains from Trade’, the amount of additional expense that Sweden would otherwise have to spend if it abated all of its required emissions by itself without trading.
Germany made a profit by abating more emissions than required: it met the regulations by abating all of the emissions that was required of it (RReq). Additionally, Germany sold its surplus to Sweden as credits, and was paid 'P' for every unit it abated, while spending less than 'P'. Its total revenue is the area of the graph (RReq 1 2 R*), its total abatement cost is area (RReq 3 2 R*), and so its net benefit from selling emission credits is the area (Δ 1-2-3) i.e. Gains from Trade
The two R* (on both graphs) represent the efficient allocations that arise from trading.
If the total cost for reducing a particular amount of emissions in the 'Command Control' scenario is called 'X', then to reduce the same amount of combined pollution in Sweden and Germany, the total abatement cost would be less in the 'Emissions Trading' scenario i.e. (X - Δ 123 - Δ def).
The example above applies not just at the national level: it applies just as well between two companies in different countries, or between two subsidiaries within the same company.
CO2 acts globally, thus its impact on the environment is generally similar wherever in the globe it is released. So the location of the originator of the emissions does not really matter from an environmental standpoint.
The policy framework should be different for regional pollutants(e.g. SO2 and NOX, and also Mercury) because the impact exerted by these pollutants may not be the same in all locations. The same amount of a regional pollutant can exert a very high impact in some locations and a low impact in other locations, so it does actually matter where the pollutant is released. This is known as the 'Hot Spot' problem.
A Lagrange framework is commonly used to determine the least cost of achieving an objective, in this case the total reduction in emissions required in a year. In some cases it is possible to use the Lagrange optimization framework to determine the required reductions for each country (based on their MAC) so that the total cost of reduction is minimized. In such a scenario, the Lagrange Multiplier represents the market allowance price (P) of a pollutant, such as the current market allowance price of emissions in Europe and the USA.
All countries face the market allowance price as existent in the market that day, so they are able to make individual decisions that would maximize their profit while at the same time achieving regulatory compliance. This is also another version of the Equi-Marginal Principle, commonly used in economics to choose the most economically efficient decision.
The best choice depends on the sensitivity of the costs of emission reduction, compared to the sensitivity of the benefits (i.e., climate damages avoided by a reduction) when the level of emission control is varied.
Because there is high uncertainty in the compliance costs of firms, some argue that the optimum choice is the price mechanism.
However, some scientists have warned of a threshold in atmospheric concentrations of carbon dioxide beyond which a run-away warming effect could take place, with a large possibility of causing irreversible damages. If this is a conceivable risk then a quantity instrument could be a better choice because the quantity of emissions may be capped with a higher degree of certainty. However, this may not be true if this risk exists but cannot be attached to a known level of GHG concentration or a known emission pathway.
A third option, known as a safety valve, is a hybrid of the price and quantity instruments. The system is essentially an emission cap and tradeable permit system but the maximum (or minimum) permit price is capped. Emitters have the choice of either obtaining permits in the marketplace or purchasing them from the government at a specified trigger price (which could be adjusted over time). The system is sometimes recommended as a way of overcoming the fundamental disadvantages of both systems by giving governments the flexibility to adjust the system as new information comes to light. It can be shown that by setting the trigger price high enough, or the number of permits low enough, the safety valve can be used to mimic either a pure quantity or pure price mechanism.
All three methods are being used as policy instruments to control greenhouse gas emissions: the EU-ETS is a quantity system using the cap and trading system to meet targets set by National Allocation Plans, the UK's Climate Change Levy is a price system using a direct carbon tax, while China uses the CO2 market price for funding of its Clean Development Mechanism projects, but imposes a safety valve of a minimum price per tonne of CO2.
It is also possible for developed countries within the trading scheme to sponsor carbon projects that provide a reduction in greenhouse gas emissions in other countries, as a way of generating tradeable carbon credits. The Protocol allows this through Clean Development Mechanism (CDM) and Joint Implementation (JI) projects, in order to provide flexible mechanisms to aid regulated entities in meeting their compliance with their caps. The UNFCCC validates all CDM projects to ensure they create genuine additional savings and that there is no leakage.
The Intergovernmental Panel on Climate Change has projected that the financial effect of compliance through trading within the Kyoto commitment period will be 'limited' at between 0.1-1.1% of GDP among trading countries. By comparison the Stern report placed the costs of doing nothing at five to 20 times higher.
In 2003 the New South Wales (NSW) state government unilaterally established the NSW Greenhouse Gas Abatement Scheme to reduce emissions by requiring electricity generators and large consumers to purchase NSW Greenhouse Abatement Certificates (NGACs). This has prompted the rollout of free energy-efficient compact fluorescent lightbulbs and other energy-efficiency measures, funded by the credits. This scheme has been criticised by the Centre for Energy and Environmental Markets of the UNSW (CEEM) because of its reliance upon offsets.
On 4 June 2007, former Prime Minister John Howard announced an Australian Carbon Trading Scheme to be introduced by 2012, but opposition parties called the plan "too little, too late. On 24 November 2007 Howard's coalition government lost a general election and was succeeded by the Labor Party, with Kevin Rudd taking over as prime minister. Prime Minister Rudd announced that a cap-and-trade emissions trading scheme would be introduced in 2010.
Australia's Commonwealth, State and Territory Governments commissioned the Garnaut Climate Change Review, an independent study by Professor Ross Garnaut on the mechanism of a potential emissions trading scheme. Its interim report was released on 21 February 2008. It recommended an emissions trading scheme that includes transportation but not agriculture, and that emissions permits should be sold competitively and not allocated free to carbon polluters. It recognised that energy prices will increase and that low income families will need to be compensated. It recommended more support for research into low emissions technologies and a new body to oversee such research. It also recognised the need for transition assistance for coal mining areas.
In response to Garnaut's draft report, the Rudd Labor government issued a Green Paper on 16 July that described the intended design of the actual trading scheme. Draft legislation will be released in December 2008, to become law in 2009.
After voluntary trials in the UK and Denmark, Phase I commenced operation in January 2005 with all 15 (now 25 of the 27) member states of the European Union participating.The program caps the amount of carbon dioxide that can be emitted from large installations, such as power plants and carbon intensive factories and covers almost half of the EU's Carbon Dioxide emissions. Phase I permits participants to trade amongst themselves and in validated credits from the developing world through Kyoto's Clean Development Mechanism.
Whilst the first phase (2005 - 2007) has received much criticism due to oversupply of allowances and the distribution method of allowances (via grandfathering rather than auctioning), Phase II links the ETS to other countries participating in the Kyoto trading system. The European Commission has been tough on Member States' Plans for Phase II, dismissing many of them as being too loose again. In addition, the first phase has established a strong carbon market. Compliance was high in 2006, increasing confidence in the scheme, although the value of allowances dropped when the national caps were met.
All EU member states have ratified the Kyoto Protocol, and so the second phase of the EU ETS has been designed to support the Kyoto mechanisms and compliance period. Thus any organisation trading through the ETS should also meet the international trading obligations under Kyoto.
The emissions trading bill passed into law on 10 September 2008.
In 1997, the State of Illinois adopted a trading program for volatile organic compounds in most of the Chicago area, called the Emissions Reduction Market System. Beginning in 2000, over 100 major sources of pollution in eight Illinois counties began trading pollution credits.
In 2003, New York State proposed and attained commitments from nine Northeast states to form a cap and trade carbon dioxide emissions program for power generators, called the Regional Greenhouse Gas Initiative (RGGI). This program is due to launch on January 1 2009 with the aim to reduce the carbon "budget" of each state's electricity generation sector to 10 percent below their 2009 allowances by 2018.
Also in 2003, U.S. corporations were able to trade CO2 emission allowances on the Chicago Climate Exchange under a voluntary scheme. In August 2007, the Exchange announced a mechanism to create emission offsets for projects within the United States that cleanly destroy ozone-depleting substances.
In 2007, the California Legislature passed the California Global Warming Solutions Act, AB-32, which was signed into law by Governor Arnold Schwarzenegger. Thus far, flexible mechanisms in the form of project based offsets have been suggested for five main project types. A carbon project would create offsets by showing that it has reduced carbon dioxide and equivalent gases. The project types include: manure management, forestry, building energy, SF6, and landfill gas capture. California is also one of seven states and three Canadian province that have joined together to create the Western Climate Initiative, which has recommended the creation of a regional greenhouse gas control and offset trading environment.
They are typically used like an offsetting scheme or to show corporate responsibility, although their issuance is unregulated, with no national registry to ensure there is no double-counting. However, it is one way that an organization could purchase its energy from a local provider who uses fossil fuels, but back it with a certificate that supports a specific wind or hydro power project.
In terms of dollars, the World Bank has estimated that the size of the carbon market was 11 billion USD in 2005, 30 billion USD in 2006, and 64 billion in 2007.
23 multinational corporations came together in the G8 Climate Change Roundtable, a business group formed at the January 2005 World Economic Forum. The group included Ford, Toyota, British Airways, BP and Unilever. On 9 June 2005 the Group published a statement stating that there was a need to act on climate change and stressing the importance of market-based solutions. It called on governments to establish "clear, transparent, and consistent price signals" through "creation of a long-term policy framework" that would include all major producers of greenhouse gases. By December 2007 this had grown to encompass 150 global businesses.
Business in the UK have come out strongly in support of emissions trading as a key tool to mitigate climate change, supported by Green NGOs.
Meaningful emission reductions within a trading system can only occur if they can be measured at the level of operator or installation and reported to a regulator. For greenhouse gases all trading countries maintain an inventory of emissions at national and installation level; in addition, the trading groups within North America maintain inventories at the state level through The Climate Registry. For trading between regions these inventories must be consistent, with equivalent units and measurement techniques.
In some industrial processes emissions can be physically measured by inserting sensors and flowmeters in chimneys and stacks, but many types of activity rely on theoretical calculations for measurement. Depending on local legislation, these measurements may require additional checks and verification by government or third party auditors, prior or post submission to the local regulator.
Another critical part is enforcement. Without effective MRV and enforcement the value of allowances are diminished. Enforcement can be done using several means, including fines or sanctioning those that have exceeded their allowances. Concerns include the cost of MRV and enforcement and the risk that facilities may be tempted to mislead rather than make real reductions or make up their shortfall by purchasing allowances or offsets from another entity. The net effect of a corrupt reporting system or poorly managed or financed regulator may be a discount on emission costs, and a (hidden) increase in actual emissions.
Critics argue that emissions trading does little to solve pollution problems overall, as groups that do not pollute sell their conservation to the highest bidder. Overall reductions would need to come from a sufficient and challenging reduction of allowances available in the system. It is possible that this would occur over time through central regulation, though some environmental groups acted more immediately by buying credits and refusing to use or sell them.
Regulatory agencies run the risk of issuing too many emission credits, diluting the effectiveness of regulation, and practically removing the cap. In this case, instead of any net reduction in carbon dioxide emissions, beneficiaries of emissions trading simply do more of the polluting activity. The National Allocation Plans by member governments of the European Union Emission Trading Scheme were criticised for this when it became apparent that actual emissions would be less than the government-issued carbon allowances at the end of Phase I of the scheme.
They have also been criticised for the practice of grandfathering, where polluters are given free allowances by governments, instead of being made to pay for them. Critics instead advocate for auctioning the credits. The proceeds could be used for research and development of sustainable technology.
Critics of carbon trading, such as Carbon Trade Watch, argue that it places disproportionate emphasis on individual lifestyles and carbon footprints, distracting attention from the wider, systemic changes and collective political action that needs to be taken to tackle climate change.
Although many economists advocate carbon trading schemes, some others favor a carbon tax instead. Possible problems with cap and trade systems include:
The problem of unstable prices can be resolved, to some degree, by the creation of forward markets in caps. Nevertheless, it is easier to make a tax predictable than the price of a cap. However, the corresponding uncertainty under a tax is the level of emissions reductions achieved.
The Financial Times wrote an article on cap and trade systems that argues that "Carbon markets create a muddle" and "...leave much room for unverifiable manipulation".
More recent criticism of emissions trading regarding implementation is that old growth forests (which have slow carbon absorption rates) are being cleared and replaced with fast-growing vegetation, to the detriment of the local communities.
Recent proposals for alternative schemes that seek to avoid the problems of Cap and Trade schemes include Cap and Share, which at May 2008 is being actively considered by the Irish Parliament, and the Sky Trust schemes.