Different greenhouse gases have different warming potentials, meaning that they trap different amounts of heat in the atmosphere. Carbon dioxide equivalent (CO2e) is a metric used to compare the emissions from various greenhouse gases (GHGs) based on their potential to contribute to global warming.
Global warming potential of GHGs
Global warming potential (GWP) is a measure of how much a particular greenhouse gas contributes to global warming over a specified period of time, typically 100 years. The GWP of a greenhouse gas is calculated by comparing its warming potential to that of carbon dioxide (CO2), which is the most common and well-known greenhouse gas.
For example, according to IPCC’s Fifth Assessment Report (AR5) on Climate Change (2014), methane (CH4) has a GWP of 28 over a 100-year period, meaning that it is 28 times more effective at trapping heat in the atmosphere than CO2 over that time period. In other words, one ton of methane emitted into the atmosphere has the same warming effect as 28 tons of CO2 over 100 years.
Other greenhouse gases, such as nitrous oxide (N2O) and fluorinated gases, have much higher GWPs than CO2. For instance, N2O has a GWP of 265 over a 100-year period, while some fluorinated gases can have GWPs in the thousands or tens of thousands.
The concept of GWP is important because it allows us to compare the warming effects of different greenhouse gases and develop strategies to reduce their impact on the environment. By understanding the GWP of various greenhouse gases, we can identify which ones are the most significant contributors to climate change and focus our efforts on reducing their emissions.
Carbon dioxide equivalent (CO2e)
Carbon dioxide equivalent (CO2e) is a metric used to compare the emissions from various greenhouse gases (GHGs) based on their potential to contribute to global warming. To compare the total emissions from different GHGs, they are converted into CO2e, which represents the amount of carbon dioxide that would have the same warming effect as the combined emissions of all the different gases. This allows for a more comprehensive understanding of the total impact of GHG emissions on the climate.
Therefore, when reporting or managing greenhouse gas emissions, it is common to express the emissions in CO2e units, which makes it easier to compare emissions from different sources and to track progress towards emission reduction goals.