This issue aims to prepare a PR to close some gaps in CDR and related emissions reporting, and fix some inconsistencies. These clarifications and changes were discussed and agreed on at the meeting of the data SWG at the IAMC meeting in 2025, and in subsequent calls between Jessica, Matt, Joana, Volker, Daniel, and also in several email exchanges including Osamu, Shinichiro and others.
There are still a lot of issues related to land-based CDR, but these will be addressed in a separate issue/PR.
Clarification of existing variables
These core principles should be clearly reflected in the variable definitions:
• Net Emissions are the difference of Gross Emissions and Carbon Removal (=Gross Removals). Carbon removal not directly associated with the energy system (as BECCS, which is reported in the Energy Supply sector) and outside the AFOLU sector is reported as “Other Capture and Removal” at the same level as “Energy and Industrial Processes”. This is a difference to Gross Emissions, where CDR associated emissions are reported as a separate demand sector (see below).
• Gross Emissions are reported as positive values of CO2 released into the atmosphere, not including CO2 captured and sequestered (CCS), and not including carbon removal. Gross emissions directly arising from CDR activities will be fully accounted for under a separate energy demand subsector “Gross Emissions|CO2|Energy|Demand|Carbon Management”. Gross emissions in the CDR sector that are not energy related, but come from industrial processes are reported in “Gross Emissions|CO2|Industrial Processes|Carbon Management”. This accounting with Carbon Removal as a separate sector is different from Net Emissions accounting, but ensures consistency with Final Energy reporting.
• Carbon Removal is to be understood as gross removals and is reported as positive values (negative values would rather be emissions and not removals). It is defined as the amount of carbon removed from the atmosphere, not accounting for associated emissions from energy or processes.
• Net Carbon Removal accounts for direct emissions associated with the specific CDR process, for example from process emissions, or from burning gas for heat. Emissions from are the power sector are not included as they are reported in Energy Supply, and not specifically as CDR emissions.
Proposed changes
-
Include CDR-related direct emissions in Gross Emissions
Gross emissions directly attributable to CDR operation are to be reported under a new subsector, Gross Emissions|CO2|Energy|Demand|Carbon Management, for energy-related CDR emissions, and Gross Emissions|CO2|Industrial Processes|Carbon Management, for non-energy, process-related CDR emissions.
-
Carbon Removal
• Remove all “Gross Removals” variables, as these are duplicates of the “Carbon Removal” variables. If they don’t exist yet in the “Carbon Removal” tree, add them there.
• Move Biochar and Enhanced Weathering out of AFOLU|Land and into dedicated top-level Carbon Removal categories: Carbon Removal|Enhanced Weathering and Carbon Removal|Biochar.
• Report associated gross emissions for both processes under the Carbon Removal sector rather than under AFOLU|Land, consistent with the general CDR-emissions-separation principle above.
• (Re-)introduce new methods or methods that got lost:
o Carbon Removal|Biomass Burial (description: burial of biomass on land)
o Carbon Removal|Ocean|Direct Ocean Capture
-
Introduction of a "Net Carbon Removal" reporting tree, parallel to "Carbon Removal", but reduced detail to avoid duplications
• Carbon Removal|| reports the gross removal effect only, excluding re-releases and process-associated emissions.
• Net Carbon Removal|| reports the net effect, i.e., Carbon Removal minus directly associated Gross Emissions (industrial-process and energy-demand subsectors), excluding emissions from power-sector use (already reported under Energy Supply).
• Net Carbon Removal values may legitimately become negative, either where associated gross emissions exceed removals, or where a stock-transfer logic moves carbon between pools (see forestry example below). This should be stated explicitly in the variable description to preempt misinterpretation of negative values as errors.
• As of now, this is mainly relevant for Net Carbon Removal|Ocean|Ocean Alkalinity Enhancement and Net Carbon Removal|Land Use, so reporting only those and not the whole tree should be sufficient for now
Worked example:
Net Carbon Removal|Ocean|Ocean Alkalinity Enhancement =
Carbon Removal|Ocean|Ocean Alkalinity Enhancement - Gross Emissions|CO2|Industrial Processes|Carbon Management|Ocean|Ocean Alkalinity Enhancement - Gross Emissions|CO2|Energy|Demand|Carbon Management|Ocean|Ocean Alkalinity Enhancement
Related changes and documentation that should go in a separate PR
-
Non-energy Secondary Energy and Primary Energy reporting for Biochar
• Introduce Primary Energy|Biomass|Biochar and Secondary Energy|Non-Energy Use|Biochar so that Primary Energy and Secondary Energy totals reconcile, consistent with existing convention for feedstocks under Final Energy|Non-Energy Use.
-
Forestry and wood-products stock-transfer logic (unchanged accounting, clarified documentation)
The underlying accounting convention for forestry and harvested wood products is not proposed to change, but should be documented consistently with the new Net Carbon Removal tree:
• Growth phase drawdown: Carbon Removal|Land Use|Re/Afforestation|Plantation
• Harvest-year emission: Gross Emissions|CO2|AFOLU|Land|Land Use and Land-Use Change|Forest Land|Wood Harvest|Planted
• Share transferred to wood products: Carbon Removal|Long-lived Materials|Timber
• End-of-life emission: Gross Emissions|CO2|AFOLU|Land|Harvested Wood Products
Resulting net effect in the harvest year:
Net Carbon Removal|Land Use|Re/Afforestation|Plantation =
Carbon Removal|Land Use|Re/Afforestation|Plantation - Gross Emissions|CO2|AFOLU|Land|Land Use and Land-Use Change|Forest Land|Wood Harvest
This value becomes negative in harvest years where harvested volume exceeds concurrent growth, which is expected behavior under stock-transfer logic and avoids double counting of CDR across the growth and harvest years. The same negativity condition applies to Carbon Removal|Long-lived Materials|* where end-of-life emissions exceed same-year removals.
-
Documentation of synthetic fuel and CCU accounting (no structural change, only documentation)
Documentation and clarification of the existing treatment of captured carbon that is used rather than stored, so that synthetic fuels remain consistently reported as carbon neutral:
- Define shares of captured carbon directed to leakage (l), storage (s), and usage (u), such that l + s + u = 1.
- Add (l + u) multiplied by Carbon Capture|Energy|Fossil and Carbon Capture|Industrial Processes (and equivalent subcategories) to Gross Emissions|CO2 and relevant subcategories. Variable definitions should be expanded to state "plus share of carbon captured but not stored."
- Require that s multiplied by Carbon Capture|[Direct Air Capture, Energy|Biomass, Energy|Synthetic Fuels] equal Carbon Removal|Geological Storage|[Direct Air Capture, Biomass, Synthetic Fuels].
Related issues
This proposal touches some existing open issues tagged cdr. Several of the changes above likely overlap in scope with one or more of those issues. Once these are addressed, the other issues can probably be closed as well:
• Related to #224 ("Gross CO2 removals missing in emission variables") — proposes the same core disaggregation as above: separating gross CO2 removals from net removals and from the remaining emissions associated with CDR technologies, so that gross emissions and gross removals reconcile to net emissions.
• Related to #365 ("Additional CDR Variables") — identifies an inconsistency in the existing Carbon Removal|{Where CO2 is Stored or Applied}|{Method} naming convention (e.g., ERW not following this pattern) and requests additional variables for Biomass Burial and non-land-based Biochar and ERW. The recategorization of Biochar and ERW follows the discussion in this issue. Additional methods are taken up as well.
• Related to #403 ("Lost CDR Methods") — flags that several CDR methods (Peatland and Wetland Restoration, Bio-Oil Storage, Mineral Products, Biomass Burial, Biomass Sinking, Other Methods) were removed from the definitions without resolving whether they should be reinstated. The most important of those are taken up here, on some others there has not yet been a decision.
@gidden @jayfuhrman @shinichirofujimoriKU could you please quickly check if this reflects your views as well? Then @danielhuppmann would help with implementing these changes.
This issue aims to prepare a PR to close some gaps in CDR and related emissions reporting, and fix some inconsistencies. These clarifications and changes were discussed and agreed on at the meeting of the data SWG at the IAMC meeting in 2025, and in subsequent calls between Jessica, Matt, Joana, Volker, Daniel, and also in several email exchanges including Osamu, Shinichiro and others.
There are still a lot of issues related to land-based CDR, but these will be addressed in a separate issue/PR.
Clarification of existing variables
These core principles should be clearly reflected in the variable definitions:
• Net Emissions are the difference of Gross Emissions and Carbon Removal (=Gross Removals). Carbon removal not directly associated with the energy system (as BECCS, which is reported in the Energy Supply sector) and outside the AFOLU sector is reported as “Other Capture and Removal” at the same level as “Energy and Industrial Processes”. This is a difference to Gross Emissions, where CDR associated emissions are reported as a separate demand sector (see below).
• Gross Emissions are reported as positive values of CO2 released into the atmosphere, not including CO2 captured and sequestered (CCS), and not including carbon removal. Gross emissions directly arising from CDR activities will be fully accounted for under a separate energy demand subsector “Gross Emissions|CO2|Energy|Demand|Carbon Management”. Gross emissions in the CDR sector that are not energy related, but come from industrial processes are reported in “Gross Emissions|CO2|Industrial Processes|Carbon Management”. This accounting with Carbon Removal as a separate sector is different from Net Emissions accounting, but ensures consistency with Final Energy reporting.
• Carbon Removal is to be understood as gross removals and is reported as positive values (negative values would rather be emissions and not removals). It is defined as the amount of carbon removed from the atmosphere, not accounting for associated emissions from energy or processes.
• Net Carbon Removal accounts for direct emissions associated with the specific CDR process, for example from process emissions, or from burning gas for heat. Emissions from are the power sector are not included as they are reported in Energy Supply, and not specifically as CDR emissions.
Proposed changes
Include CDR-related direct emissions in Gross Emissions
Gross emissions directly attributable to CDR operation are to be reported under a new subsector, Gross Emissions|CO2|Energy|Demand|Carbon Management, for energy-related CDR emissions, and Gross Emissions|CO2|Industrial Processes|Carbon Management, for non-energy, process-related CDR emissions.
Carbon Removal
• Remove all “Gross Removals” variables, as these are duplicates of the “Carbon Removal” variables. If they don’t exist yet in the “Carbon Removal” tree, add them there.
• Move Biochar and Enhanced Weathering out of AFOLU|Land and into dedicated top-level Carbon Removal categories: Carbon Removal|Enhanced Weathering and Carbon Removal|Biochar.
• Report associated gross emissions for both processes under the Carbon Removal sector rather than under AFOLU|Land, consistent with the general CDR-emissions-separation principle above.
• (Re-)introduce new methods or methods that got lost:
o Carbon Removal|Biomass Burial (description: burial of biomass on land)
o Carbon Removal|Ocean|Direct Ocean Capture
Introduction of a "Net Carbon Removal" reporting tree, parallel to "Carbon Removal", but reduced detail to avoid duplications
• Carbon Removal|| reports the gross removal effect only, excluding re-releases and process-associated emissions.
• Net Carbon Removal|| reports the net effect, i.e., Carbon Removal minus directly associated Gross Emissions (industrial-process and energy-demand subsectors), excluding emissions from power-sector use (already reported under Energy Supply).
• Net Carbon Removal values may legitimately become negative, either where associated gross emissions exceed removals, or where a stock-transfer logic moves carbon between pools (see forestry example below). This should be stated explicitly in the variable description to preempt misinterpretation of negative values as errors.
• As of now, this is mainly relevant for Net Carbon Removal|Ocean|Ocean Alkalinity Enhancement and Net Carbon Removal|Land Use, so reporting only those and not the whole tree should be sufficient for now
Worked example:
Net Carbon Removal|Ocean|Ocean Alkalinity Enhancement =
Carbon Removal|Ocean|Ocean Alkalinity Enhancement - Gross Emissions|CO2|Industrial Processes|Carbon Management|Ocean|Ocean Alkalinity Enhancement - Gross Emissions|CO2|Energy|Demand|Carbon Management|Ocean|Ocean Alkalinity Enhancement
Related changes and documentation that should go in a separate PR
Non-energy Secondary Energy and Primary Energy reporting for Biochar
• Introduce Primary Energy|Biomass|Biochar and Secondary Energy|Non-Energy Use|Biochar so that Primary Energy and Secondary Energy totals reconcile, consistent with existing convention for feedstocks under Final Energy|Non-Energy Use.
Forestry and wood-products stock-transfer logic (unchanged accounting, clarified documentation)
The underlying accounting convention for forestry and harvested wood products is not proposed to change, but should be documented consistently with the new Net Carbon Removal tree:
• Growth phase drawdown: Carbon Removal|Land Use|Re/Afforestation|Plantation
• Harvest-year emission: Gross Emissions|CO2|AFOLU|Land|Land Use and Land-Use Change|Forest Land|Wood Harvest|Planted
• Share transferred to wood products: Carbon Removal|Long-lived Materials|Timber
• End-of-life emission: Gross Emissions|CO2|AFOLU|Land|Harvested Wood Products
Resulting net effect in the harvest year:
Net Carbon Removal|Land Use|Re/Afforestation|Plantation =
Carbon Removal|Land Use|Re/Afforestation|Plantation - Gross Emissions|CO2|AFOLU|Land|Land Use and Land-Use Change|Forest Land|Wood Harvest
This value becomes negative in harvest years where harvested volume exceeds concurrent growth, which is expected behavior under stock-transfer logic and avoids double counting of CDR across the growth and harvest years. The same negativity condition applies to Carbon Removal|Long-lived Materials|* where end-of-life emissions exceed same-year removals.
Documentation of synthetic fuel and CCU accounting (no structural change, only documentation)
Documentation and clarification of the existing treatment of captured carbon that is used rather than stored, so that synthetic fuels remain consistently reported as carbon neutral:
Related issues
This proposal touches some existing open issues tagged cdr. Several of the changes above likely overlap in scope with one or more of those issues. Once these are addressed, the other issues can probably be closed as well:
• Related to #224 ("Gross CO2 removals missing in emission variables") — proposes the same core disaggregation as above: separating gross CO2 removals from net removals and from the remaining emissions associated with CDR technologies, so that gross emissions and gross removals reconcile to net emissions.
• Related to #365 ("Additional CDR Variables") — identifies an inconsistency in the existing Carbon Removal|{Where CO2 is Stored or Applied}|{Method} naming convention (e.g., ERW not following this pattern) and requests additional variables for Biomass Burial and non-land-based Biochar and ERW. The recategorization of Biochar and ERW follows the discussion in this issue. Additional methods are taken up as well.
• Related to #403 ("Lost CDR Methods") — flags that several CDR methods (Peatland and Wetland Restoration, Bio-Oil Storage, Mineral Products, Biomass Burial, Biomass Sinking, Other Methods) were removed from the definitions without resolving whether they should be reinstated. The most important of those are taken up here, on some others there has not yet been a decision.
@gidden @jayfuhrman @shinichirofujimoriKU could you please quickly check if this reflects your views as well? Then @danielhuppmann would help with implementing these changes.