Add gross-carbon-removal variables

[danielhuppmann]

Add variables for carbon-removal technologies as requested (with some slight streamlining and simplifications).

[danielhuppmann]

As mentioned also in the email to @IAMconsortium/common-definitions-emissions, I find it odd that removal by geological storage is not included in this list...

[jayfuhrman]

Looks good. Suggested definitions for

Afforestation: Carbon dioxide (CO2) removed from the atmosphere by increasing forested land area and thereby increasing vegetation and soil carbon stocks.

Agroforestry: Carbon dioxide (CO2) removed from the atmosphere by integrating trees into crop and pasture lands to increase vegetation and soil carbon stocks

Biochar: Carbon dioxide (CO2) removed from the atmosphere through the conversion of biomass to recalcitrant carbon via pyrolysis and its subsequent application to croplands to increase soil carbon stocks

Soil carbon management: Carbon dioxide (CO2) removed from the atmosphere by increasing organic carbon content through no or low-till agricultural practices, or manure or compost application. Note that biochar should be reported as its own category

Note that not all models have capability to easily report gross as opposed to net CO2 emissions from land-use change so we may need to have a broader discussion on how to handle this

[danielhuppmann]

Thanks @jayfuhrman, extended the description of the removal-options per your comment.

[jayfuhrman]

We should add DACCS and BECCS to carbon removal variables (and synthetic fuels) as well. @strefler @gidden

[gidden]

Hi @jayfuhrman - very much agree with your approach. We have an overview figure here: https://www.stateofcdr.org/s/SoCDR-2Ed-Fig-14-for-website.pdf

Would you mind adapting this PR to include the categories you mentioned, including tiers (e.g., Forestry|Aforestation) and cross check the final SoCDR list? Happy to approve after that!

[danielhuppmann]

Thanks @gidden.

I implemented the changes in line with the State of CDR variables, with the following changes:

• I did not (yet) include the sub-categories of forestry and of peatland & (coastal) wetland restoration - not sure if any models can even report at that level of detail?
• Not all "Materials" variables in your initial proposal are included in SoCDR, in particular plastics.

  - Materials:
      description: use of long-lived materials with centennial to millennial residence times
  - Materials|Cement:
      description: use of cement
  - Materials|Plastics:
      description: use of long-lived plastics
  - Materials|Timber:
      description: use of long-lived timber
  - Materials|Other:
      description: use of other long-lived materials

  Should this be added? And is "Durable Wood Products" really a removal option? Depends on the expected lifetime, I guess - should this be clarified?

Also, I notice that there is no "Geological Storage" variable, this is only the aggregate of BECCS and DACCS, and there is no way to report non-bioenergy process-based CCS. Is that really the way to go forward for IAM reporting?

[gidden]

Hi @danielhuppmann - thanks!

I did not (yet) include the sub-categories of forestry and of peatland & (coastal) wetland restoration - not sure if any models can even report at that level of detail?

I think we do want them in as these are methods actively being investigated and will also potentially show up in historical datasets as well.

Should this be added? And is "Durable Wood Products" really a removal option? Depends on the expected lifetime, I guess - should this be clarified?

Yes, we should keep plastics. However, that is more a CCU/S than CDR (depending on how the plastics are disposed). Yes, DWP are a short-lived CDR option. In principle, teams should take care to account for the duration and provide carbon flux returning to the atmosphere also in this variable. Maybe useful to include in the description?

Also, I notice that there is no "Geological Storage" variable, this is only the aggregate of BECCS and DACCS, and there is no way to report non-bioenergy process-based CCS. Is that really the way to go forward for IAM reporting?

My understanding from this PR Is that is it purely about carbon removal technologies, and includes BECCS and DACCS based on the changelog. We definitely do not want to report fossil CCS here. Rather, that would be under a different tree related to carbon management. I understood that as part of @strefler 's proposal and if we agree suggest that can be brought in in another PR.