Reporting Units: carbon dioxide equivalents (CO2-e)
On-farm GHG emissions come from multiple sources. The different types of GHG have different global warming potential (see table below).
Both methane and nitrous oxide trap more heat in the atmosphere compared to carbon dioxide, and therefore have a higher global warming potential.
A GHG baseline standardises these contributions to a common unit called carbon dioxide equivalent (CO2-e). This unit recognises the amount of warming caused by that gas over an agreed time frame. One hundred years is the internationally agreed reporting time frame.
Global warming potential of the major GHGs (after the IPCC Fifth Assessment Report (AR5)1.
|
Chemical Name |
Chemical Formula |
Global Warming Potential |
Average Lifetime in the Atmosphere |
|
Carbon Dioxide |
CO2 |
1 |
Hundreds - thousands of years |
|
Methane |
CH4 |
28 |
12 years |
|
Nitrous Oxide |
N2O |
265 |
109 years |
1 IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.