Carbon dioxide is arguably the most important greenhouse gas (GHG) because of the sheer volume of it that we release into the atmosphere from fossil fuel sources. Although the other GHGs are much more potent, CO2 is by far the most abundant, making it the greatest contributor to global warming. Vast amounts of CO2 are emitted during the burning of fossil fuels, which have been and still are our main source of power.
The next most important GHGs are methane and nitrous oxide, both of which are major emissions from agriculture.
Because CO2 is the most abundant GHG we tend to express all emissions in terms of their carbon dioxide equivalence (CO2e).
By converting GHG emissions to carbon equivalence, it is possible to evaluate their overall combined effect on the planet's climate. Methane, for example, is around 23 times more potent as a GHG than CO2: one tonne of methane has the same effect on the atmosphere as 23 tonnes of CO2.
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