Before the Euro was introduced almost 10 years ago, European travelers and businesspeople alike were stuck with pockets and plastic baggies full of change. There were two kinds of francs, kroners, lire, guilders … each with their own fluctuating value.
We found all that switching back and forth as we crossed borders, not only confusing, but totally wasteful in terms of energy spent exchanging money and trying to figure out the value of something. If a CD in Switzerland cost 20 Swiss francs, and the same CD in France cost 140 francs, which was the better deal?
Thankfully, the powers that be decided to create a unit of currency, the Euro, so that an apple in Spain will cost about the same as an apple in Holland. The ultimate aim was that people could trade, work and shop between borders more fluidly.
When it comes to calculating the “value” of a greenhouse gas offset, the decision makers – economists and scientists – needed a sort of “Euro.” But in the case of greenhouse gases, it would be extra complicated to find a common currency, because comparing methane gas to carbon dioxide, isn’t like comparing apples to oranges.
There was just so much difference between the potency and availability of each gas, that a new currency system just for greenhouse gases had to be built.
Methane Molecule
One ton of methane gas, for example, has 21 times the potency of a ton of CO2 in its ability to contribute to global warming.
Because all the gases have such different contributions (see our last post on this), it was decided that each gas would be given a number relative to its impact, compared to CO2.
CO2 Molecule
If CO2 has global warming potential = 1, it was calculated relative to carbon that methane’s impact is 21 and so on, so that…
nitrous oxide = 271
perfluorocarbons = 6,000-9,000
hydrofluorocarbons = 1,000-10,000
sulphur hexafluoride = 23,900
For the purpose of trading or offsetting emissions, a base currency was needed. Today it is CO2e (for carbon dioxide equivalent), and when an organization or individual calculates its greenhouse emissions, they are reported in the equivalent weight of CO2, the CO2e.
Update: See also our post on methane.
(image credit: emdot)