NGER global warming potential values are set in regulation 2.02 of the NGER Regulations and are drawn from the IPCC Fifth Assessment Report (AR5). They convert each greenhouse gas into carbon dioxide equivalence (CO2-e). Because the values are set in regulation, a change needs an amendment to the NGER Regulations rather than a choice by each reporter.
Key points
- Values are set in regulation 2.02 of the NGER Regulations
- Current values come from the IPCC Fifth Assessment Report
- Methane is 28 and nitrous oxide 265
- Earlier years used AR2 and AR4 values and are not restated
The main values
| Gas | Global warming potential |
|---|---|
| Carbon dioxide (CO2) | 1 |
| Methane (CH4) | 28 |
| Nitrous oxide (N2O) | 265 |
| Sulphur hexafluoride (SF6) | 23,500 |
| HFC-23 | 12,400 |
| HFC-32 | 677 |
| HFC-134a | 1,300 |
| Perfluoromethane (CF4) | 6,630 |
| Perfluoroethane (C2F6) | 11,100 |
Regulation 2.02 sets a value for every listed hydrofluorocarbon and perfluorocarbon. In practice, one tonne of methane is reported as 28 tonnes CO2-e and one tonne of nitrous oxide as 265 tonnes CO2-e.
How the values have changed
NGER has used three sets of values. Second Assessment Report values applied from 2008-09 to 2014-15, Fourth Assessment Report values from 2015-16 to 2019-20, and Fifth Assessment Report values from 2020-21. Methane, for example, moved from 21 to 25 to 28.
Comparing years
The Clean Energy Regulator does not adjust data already reported when values change. To compare years reported under different values, one year must be adjusted to match the other. This matters when building a trend from the Regulator’s published datasets, because each year reflects the values in force when it was reported.
Other frameworks
AASB S2 takes a different approach. Where an entity converts gases to CO2-e itself, it must use 100-year global warming potential values from the latest IPCC assessment, which AASB S2 specifies as the Sixth Assessment Report (AR6). Emission factors already expressed in CO2-e do not need to be recalculated. A corporation reporting under both needs to track which values each figure uses. The Safeguard Mechanism uses NGER figures, so NGER values also drive a facility’s position against its baseline.
Why it matters
For methane-intensive operations, such as coal mining, oil and gas and landfill, a change in methane’s value moves reported CO2-e even when physical emissions are unchanged.
References & sources
Primary regulatory documents and authoritative references underpinning this answer.