Carbon dioxide equivalent

Carbon dioxide equivalent

Carbon dioxide equivalent (CDE) and Equivalent carbon dioxide (or CO2) are two related but distinct measures for describing how much global warming a given type and amount of greenhouse gas may cause, using the functionally equivalent amount or concentration of carbon dioxide (CO2) as the reference.

Contents

Global warming potential

Carbon dioxide equivalency is a quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO2 that would have the same global warming potential (GWP), when measured over a specified timescale (generally, 100 years). Carbon dioxide equivalency thus reflects the time-integrated radiative forcing of a quantity of emissions or rate of greenhouse gas emission—a flow into the atmosphere—rather than the instantaneous value of the radiative forcing of the stock (concentration) of greenhouse gases in the atmosphere described by CO2e.

The carbon dioxide equivalency for a gas is obtained by multiplying the mass and the GWP of the gas. The following units are commonly used:

  • By the UN climate change panel IPCC: billion metric tonnes of CO2 equivalent (GtCO2eq).
  • In industry: million metric tonnes of carbon dioxide equivalents (MMTCDE).
  • For vehicles: g of carbon dioxide equivalents / km (gCDE/km).

For example, the GWP for methane over 100 years is 25 and for nitrous oxide 298. This means that emissions of 1 million metric tonnes of methane and nitrous oxide respectively is equivalent to emissions of 25 and 298 million metric tonnes of carbon dioxide.[1]

Equivalent carbon dioxide

Equivalent CO2 (CO2e) is the concentration of CO2 that would cause the same level of radiative forcing as a given type and concentration of greenhouse gas. Examples of such greenhouse gases are methane, perfluorocarbons, and nitrous oxide. CO2e is expressed as parts per million by volume, ppmv.

CO2e calculation example:
  • The radiative forcing for pure CO2 is approximated by RF = αln(C / C0) where C is the present concentration, α is a constant, 5.35 and C0 the pre-industrial concentration, 278 ppm. Hence the value of CO2e for an arbitrary gas mixture with a known radiative forcing is given by C0exp(RF / α) in ppmv.
  • To calculate the radiative forcing for a 1998 gas mixture, IPCC 2001 gives the radiative forcing (relative to 1750) of various gases as: CO2=1.46 (corresponding to a concentration of 365 ppmv), CH4=0.48, N2O=0.15 and other minor gases =0.01 W/m2. The sum of these is 2.10 W/m2. Inserting this to the above formula, we obtain CO2e = 412 ppmv.

See also

References

  1. ^ IPPC AR4, Table 2.14, p.212

External links

Bibliography

  • Gohar and Shine, Equivalent CO2 and its use in understanding the climate effects of increased greenhouse gas concentrations, Weather, Nov 2007, p307-311.

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Carbon Dioxide Equivalent — (CDE)   A metric measure used to compare the emissions from various greenhouse gases based upon their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as million metric tons of carbon dioxide equivalents (MMTCDE)… …   Energy terms

  • Carbon dioxide equivalent —   The amount of carbon dioxide by weight emitted into the atmosphere that would produce the same estimated radiative forcing as a given weight of another radiatively active gas. Carbon dioxide equivalents are computed by multiplying the weight of …   Energy terms

  • carbon dioxide equivalent — noun a measure of how much global warming a greenhouse gas may give rise to, made by determining the amount of CO2 required to achieve the equivalent radiative forcing, and using this CO2 quantity as a reference point. Abbrev.: CDE …  

  • Carbon dioxide in the Earth's atmosphere — Carbon dioxide forms approximately 0.04% of the Earth s atmosphere. It is essential to photosynthesis in plants and other photoautotrophs, and is also a prominent greenhouse gas due to its radiative forcing strength.ConcentrationAs of November… …   Wikipedia

  • Carbon Dioxide — (CO2)   A colorless, odorless, non poisonous gas that is a normal part of Earth s atmosphere. Carbon dioxide is a product of fossil fuel combustion as well as other processes. It is considered a greenhouse gas as it traps heat (infrared energy)… …   Energy terms

  • Carbon dioxide — Dioxide Di*ox ide (?; 104), n. [Pref. di + oxide.] (Chem.) (a) An oxide containing two atoms of oxygen in each molecule; binoxide. (b) An oxide containing but one atom or equivalent of oxygen to two of a metal; a suboxide. [Obs.] [1913 Webster]… …   The Collaborative International Dictionary of English

  • Carbon emission trading — Carbon emissions trading is emissions trading specifically for carbon dioxide (calculated in tonnes of carbon dioxide equivalent or tCO2e) and currently makes up the bulk of emissions trading.It is one of the ways countries can meet their… …   Wikipedia

  • Carbon (disambiguation) — Carbon may refer to:Chemical element*Carbon, the chemical element *Carbon black, a filler often used to improve the properties of rubber or plastic compounds *Carbon chauvinism, a term meant to disparage the assumption that the molecules… …   Wikipedia

  • Carbon accounting — is the accounting undertaken to measure the amount of carbon dioxide equivalents that will not be released into the atmosphere as a result of Flexible Mechanisms projects under the Kyoto Treaty. These projects thus include (but are not limited… …   Wikipedia

  • Carbon tax — Part of a series on Green economics Concepts …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”