1/6: I suggest separating mitigation commitments, with strictly no substitution between them! For example:
1) CO2 from energy use
2) CO2 from industrial processes
3) CO2 form land use etc (LULUCF)
4) non-CO2 GHGs from LULUCF
5) non-CO2 GHGs from industry
6) Carbon Dioxide Removal

2/6: By definition the 'net' of net-zero permits &even encourges substitution. Not only does this facilitate the unscrupulous, but there are v.different physical,chemical &temporal characteristics of different GHGs from different sources that make substitution deeply problematic.

3/6: A word search through the huge library of CCC reports since 2008 demonstrates how "net zero" is a relatively new framing of the challenge. @James_BG comment could be read as suggesting that for a decade the CCC had no plan. I see net-zero hiding expedient political choices?

4/6: Our analysis of Paris suggests the UK's net-zero framing is more inline with ~2.5°C than 1.5-2°C. https://tandfonline.com/doi/full/10.1080/14693062.2020.1728209 But combining net-zero with the CCC's rejection of both 1.5-2°C & a long-term carbon budget in favour of "highest possible ambition" hides this huge gap.

5/6: The scale of cuts needed to meet our Paris temperature & equity commitments requires profound changes to all facets of society. Substitution between very different sources & sinks facilitates a whole industry of Machiavellian accounting. Keep the framing simple & direct.

6/6: Interested to hear your thoughts
@James_BG & @DrSimEvans on the merits/drawbacks of separate targets as an alternative to the net-zero framing (where substitution occurs between sources & sinks that have very different physical, chemical, temporal, etc, characteristics).