Some GHGs are more potent than others. To make it possible to talk about the effect of greenhouse gases in general, the “radiative forcing” – impact on the climate – of each gas is converted into the amount of CO2 required to produce the same effect. CO2 is thus the currency of climate change.
The unit used is CO2e, meaning carbon dioxide equivalent. Expressing the global warming potential of various GHGs in terms of the amount of carbon dioxide required to produce the same effect makes the impact of differing emissions easier to understand. It also enables a trading system to exist, much as common currencies help economic markets to flourish... or flounder!
When we talk about reducing our carbon footprint, we really mean reducing our greenhouse gas emissions generally.
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