IAMconsortium
Emission species levels 2 and 3 are identical
When checking the emission variables for a recent project, I noticed that the emission species for levels 2 and 3 are identical.
- https://github.com/IAMconsortium/common-definitions/blob/258c943fdbc16f362865367dba68daba50bcac93/definitions/variable/emissions/tag_level-2-species.yaml
- https://github.com/IAMconsortium/common-definitions/blob/258c943fdbc16f362865367dba68daba50bcac93/definitions/variable/emissions/tag_level-3-species.yaml I don't think that this is intended.
From my perspective, it would be useful to have one level covering all species that have been used for the CMIP/ScenarioMIP harmonization process (see Gidden et al. 2019). This would require adding a more complete breakdown of Kyoto F-gases, so C2F6, CF4, SF6 and HFCs are missing. At the moment only C2F6 is included which seems odd.
For background, we initially had multiple levels to support different levels of detail for different species. Last week, @volker-krey said he preferred to have all possible combinations of species and variables even if some combinations don’t make sense.
Extending the level-3 list was the easiest quickfix.
If we indeed go with the “all combinations” approach, we can probably simplify and remove the level-3 (and level-2) tag lists.
Related comment: I think "fossil carbon dioxide (CO2)" should be revised to "carbon dioxide (CO2)". Otherwise, this would exclude CO2 emissions from land-use change https://github.com/IAMconsortium/common-definitions/blob/main/definitions/variable/emissions/tag_level-1-species.yaml#L5
We initially had this as all CO2, but changed for consistency with previous projects, see https://github.com/IAMconsortium/common-definitions/pull/113.
It would be good to have clarity, but please do that as a separate discussion, not in this issue.