Durable carbon dioxide removals: Let’s get it right now, not fix it later.

Cascade Climate, working with stakeholders from the voluntary carbon market and the scientific community, released a framework for quantifying durable carbon dioxide removals (dCDR) through enhanced rock weathering. It is well worth a read, as it includes guidance that should be considered for all types of dCDR. As they say, now is the time to think about how we assess the greenhouse gas integrity of all these project types – before our framework is set in stone for one or another type. Early decisions about how to do the accounting in one type may later be cited when assessing another type. The number of active projects is extremely limited at this point. There is still plenty of time to get the accounting right before the market scales to the levels needed.?

Our takeaways from the report are three-fold:?

1. Rigorous approaches are possible with the current state of the science, as long as we make conservative choices.
2. Carbon credits that are used as offsets should reflect “what the atmosphere sees” not what it might expect to see in the future (often called “ex-ante” credits).?
3. CDR methodologies and protocols should align in this regard to ensure greenhouse gas integrity and fairness in the market.

Cascade Climate's report starts with:

“Ideally, carbon credits that are used to offset emissions should be awarded in an ex-post manner, after atmospheric CDR actually occurs….However, a range of operational and normative choices, as well as precedent from other CDR pathways, may also play a role in determining when credits are issued for CDR deployments.”?

The greater VCM community should weigh in on ‘normative’ choices: what decisions are most consistent with well-established best practices in greenhouse gas accounting and carbon crediting? Which are consistent with the approach of the ICVCM?

Are ‘operational’ choices the best basis for decisions about accounting???

The influence of ‘precedent from other CDR pathways’ is an important reminder: if we have made mistakes in the accounting for some types, let’s fix them. Let’s not propagate the mistake across the rest of the market. We are still in the early stages. The market is eager for durable CDR – but we are still rebuilding trust in the voluntary carbon market. Now is not the time to make decisions of expediency. Now is the time to get it right.?

For enhanced rock weathering, the recommendation for ‘when to credit’ involves detailed tracking and waiting until weathering products are exported from the NFZ (near field zone). “This approach most closely allows for crediting when CDR is biogeochemically realized, does not rely on predictive modeling to estimate NFZ fluxes, and ensures that each NFZ loss process is constrained through empirical measurement.”

Other options were considered, but the group’s recommendation was to focus on the actual dynamics of the weathering process as the basis for crediting removals. They noted the contrast with approaches already in place for some other CDR protocols (e.g., a simple 15-year emissions timeframe for baseline emissions from waste used in biochar production). Dealing with the early legacy of CDR protocols should be part of a community-wide, ongoing conversation.?

Cascade Climate puts forward two basic options for how to account for upstream lifecycle emissions. One option is to account for all such emissions in the first reporting period. “This is maximally conservative and closest to when the atmosphere feels the effect of the life cycle emissions….” We would agree that this approach has the highest GHG integrity. They say that this is “... arguably overly punitive given that it does not conform with current precedent in other CDR pathways (e.g., direct air capture).” Instead, we would argue for the need to promote best practices across the board.?

The other approach is more in line with some other CDR pathways: to amortize those emissions over time, which results in “ex-ante” crediting – i.e. issuing credits prior to the atmosphere seeing the actual benefit. Cascade Climate notes that acceptance of the more conservative, atmosphere-centric approach would require a coherent, consistent framework to be adopted across CDR pathways. We agree that otherwise, there is a risk of creating an unfair playing field.?

The report presents some compelling arguments about how to credit removals from enhanced rock weathering, but it also reminds us about the need for calibration across all CDR protocols and a good hard look at how the accounting gets done. Many buyers may actually be unaware that they are purchasing credits that do not (yet) represent a benefit to the atmosphere to offset their emissions. Some may simply be purchasing such credits as a contribution to solving the climate crisis – which is a valid investment that the world needs.

We urge the community to have a conversation on this topic rather than settle for something that does not advance best practices in carbon accounting. That includes revisiting the way life-cycle analysis should work for the carbon market.

See the framework from Cascade Climate here .