Jump to content

Carbon offsets and credits

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Dieguez (talk | contribs) at 00:24, 5 January 2007. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

A carbon offset zeros out (offsets) all or part of the carbon dioxide (CO2) emissions of a party, by reducing the emissions—or increasing the carbon dioxide absorption—of another party. This reduces net greenhouse gas emissions with the goal of combating global warming. Effectively offsetting the emissions of an activity makes that activity "carbon neutral".

World net carbon-emission rates would need to be reduced approximately 60%–80% by 2050 to keep global temperatures within 1°C above present. A 1° rise would likely raise sea levels by no more than approximately 5 meters (16 feet) over the next 200 to 2000 years, whereas a 3°C rise would likely raise sea levels by 25 ± 10 meters (82 ± 33 feet)[2] ([3]Section 6). Carbon offsets can provide individuals, businesses and governments a way to reduce their net emissions farther than what they have achieved through their efforts to conserve energy and use renewable energy.

Carbon offsets may be purchased from a variety of commercial and non-commercial organizations for US$0.11 to US$20.00 per metric ton of CO2[4][5]. (The UK government purchased offsets for the air travel required for the 31st G8 summit.) The fossil fuel usage of one average resident of the United States produces 20 metric tons (= 22 American tons = 44,000 pounds) of carbon dioxide per year (in other words, annual carbon dioxide emissions per capita); other countries range from 0 to 23 metric tons of annual carbon dioxide emissions per capita[6]. The world average is 4.0 metric tons, the developed country average is 12.9 metric tons, and the developing country average is 2.2 metric tons of annual carbon dioxide emissions per capita([7],Indicator 28). Carbon offset providers often provide a "carbon calculator" to estimate a person's or business's carbon dioxide emissions arising from consumption of fossil fuels — a sort of ecological footprint for global warming.


Types of offset

A wide variety of offset actions are available and possible: the most frequent is reforestation, followed by various renewable energy and energy conservation projects, sometimes certified as CDM credits, and sometimes in the form of allowances purchased from the EU ETS.

Reforestation

The most common offset is reforestation. Trees absorb carbon dioxide (sequester carbon) by using photosynthesis to combine water with carbon dioxide from the atmosphere, thereby forming wood and releasing oxygen. Thus, forests that are increasing in area or density are carbon dioxide sinks, and mature forests are carbon stores. (If a tree or its lumber burns after a time, that tree's carbon sequestration was temporary — As long as the forest as a whole is left standing, the forest remains a store of carbon that has been removed from the atmosphere.) However, the global cooling effect of forests is partially counteracted: For example, the planting of new forests may initially release some of the soil's carbon into the atmosphere as greenhouse gasses. Also, reforestation decreases the reflectiveness (albedo) of the land, thus decreasing the reflection of sunlight back into outer space. Regarding the overall effect of forest protection and forestation, a 2002 scientific article concluded that "an extensive global carbon sequestration programme has the potential to make a particularly significant contribution to controlling the rise in CO2 emissions in the next few decades."[8][1]. Although uncertainty remains about details of sequestration science and accounting, and although there has been criticism from those community groups that have been adversely affected by certain tree-planting projects, other community groups actively seek tree-planting materials and technical guidance, then voluntarily plant trees to improve the productivity of their lands[9].

It is important to take into account that the global cooling effect of reforestation's carbon sequestration is partially counteracted by other effects of reforestation, particularly in temperate climates. Compared with less vegetated lands, forests affect climate in three main ways: (1) cooling Earth by funtioning as carbon sinks and carbon stores, (2) cooling Earth by evaporating water to the atmosphere and increasing cloudiness, and (3) warming Earth by absorbing a high percentage of sunlight due to the low albedo of forest's dark surfaces. Climate change mitigation strategies that promote reforestation generally have taken only the first effect into account. A study presented in December 2006 [10],[11] combined all these effects and found that tropical reforestation has a significant net cooling effect, whereas reforestation of temperate regions provides little or no net global cooling, primarily due to the fact that reforestation results in much lower snow-season albedos.

To plant forests outside of the tropics to mitigate climate change is a waste of time

said Ken Caldeira[12], a study co-author from the Carnegie Institution. "To prevent climate change, we need to transform our energy system. It is only by transforming our energy system and preserving natural habitat, such as forests, that we can maintain a healthy environment. To prevent climate change, we must focus on effective strategies and not just ‘feel-good’ strategies." The IPPC has concluded that "The mitigation costs through forestry can be quite modest (US$0.1–US$20 / metric ton carbon dioxide) in some tropical developing countries.... The costs of biological mitigation, therefore, are low compared to those of many other alternative measures"[13]. In tropical reforestation, as little as US$90 will plant 900 trees[14], enough to annually remove as much carbon dioxide as is annually generated by the fossil-fuel usage of an average American. The relative cost-effectiveness of tropical reforestation carbon offsets is partly because trees grow 3 times faster in the tropics than in temperate zones: each tree in the rainy tropics removes about 22 kg (about 50 pounds) of carbon dioxide from the atmosphere each year; 40 years after planting, the average tropical tree will have removed about 880 kg (about 2000 pounds) of carbon dioxide[15]. The cost-effectiveness of tropical reforestation is also because many people from tropical developing countries are eager to voluntarily plant the tree seeds—and to nurture and transplant the seedlings—to improve the productivity of their lands[16].

Renewable energy and energy conservation

Many renewable energy offsets fund wind or solar energy[17]; others fund projects that use farm biowaste to generate energy[18].[19]

Another renewable energy offset trains communities in developing countries how to produce biodiesel from a species of tropical tree nut. This approach produces biodiesel for about US$2.50 per gallon, compared with local fossil-fuel prices of about US$5 per gallon[20].

A common energy-conservation offset involves compensating a company that has reduced its greenhouse-gas emissions, by purchasing a greenhouse-gas emission allowance from the company on the Chicago Climate Exchange. The offset provider then retires the allowance to prevent other companies from purchasing the allowance to emit greenhouse gas[21][22] [23].

One cost effective energy-conservation offset is training developing-world communities in the production, sale, and use of fuel-efficient stoves. Almost half of the world's people burn wood (or dung or fiber) for their cooking and heating needs. Fuel-efficient cookstoves can reduce fuelwood consumption by 30 to 50%[2].

Accounting for and verifying reductions

Systems of accounting differ somewhat, on what constitutes a valid offset between voluntary reduction systems and mandatory ones. Accounting of offsets may address the following basic areas, and it is in these areas where differences of opinion between emitters, regulators, environmentalists, and project developers typically exist:

  • Baseline - What scenario of emissions would occur in the absence of a proposed project?
  • Surplus - Are the reductions already required by some other law or regulation?
  • Incremental - Would the project have happened anyway?
  • Permanence - Are some benefits of the reductions reversible? (for example, cutting trees to burn the wood)
  • Leakage - Does implementing the project cause higher emissions outside the project boundary?

An additional problem is that no formal guidelines or regulations have been formulated, that set out what qualifies and in what quantities.

Carbon Neutral Consumer Products

Carbon neutrality is quickly becoming an eco-label, with companies offseting their carbon emissions and using the label to appeal to environmentally conscious consumers.


References

  1. ^ Philos Transact A Math Phys Eng Sci 2002Aug15; 360:1567-91.
  2. ^ Global Cooling Answer Book, Second Edition, 2005, authored and published by Trees for the Future, p. 14[1].
  • Osborne, Tracey (2005). "Carbon offsets as an economic alternative to large-scale logging: a case study in Guyana". Ecological Economics. 52 (4). {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  • Staff writer (2006). "Co2nned: The carbon offsets scam exposed". New Internationalist. {{cite journal}}: Cite has empty unknown parameters: |quotes= and |coauthors= (help); Unknown parameter |month= ignored (help)

See also

Information

Retrieved from "https://en.wikipedia.org/w/index.php?title=Carbon_offsets_and_credits&oldid=98534899"