By Leo Mercer, Josh Burke and Xin Chen
Today, the Grantham Research Institute, in collaboration with AlliedOffsets, is relaunching a novel and improved tool aimed at improving transparency in the carbon dioxide removal (CDR) market. The TRACEcdr tool (Transparent Reporting and Certification) serves as an interactive visualisation platform and dashboard, giving policymakers, CDR developers and purchasers insight into the complex landscape of carbon removal monitoring, reporting and verification (MRV).
The continued ideation of novel CDR methods, and the reimagining of methods by which to precisely measure net removal or net negativity by CDR activities, means MRV protocols in the CDR space are constantly emerging and reorienting. Maintaining a systematic overview of activity and evolution is challenging. We are not alone in recognising this issue; other organisations are also working to shine a light on this complexity and facilitate interoperability across protocols and jurisdictions – see RMI, CSRI and Calyx, for example.
The tool has been created to support rapid understanding of the nascent CDR market at a glance, allowing users – e.g. policymakers, investors and developers – to appreciate the diversity of methods and quantification standards across the CDR ecosystem such as where activity is happening, by what methods and how this changes over time, as well as the lifecycle accounting, baseline, permanence, additionality and leakage considerations included in each MRV protocol.
A recurrent trend illuminated by the tool is the dominance of MRV protocols for ‘land-based biological’ methods. Although methods like DAC – direct air carbon capture – have dominated CDR discussion and funding, whether measured by the sum of MRV protocols, number of projects or credit issuance, the overwhelming majority of activity is in afforestation, reforestation or improved forest management and other projects that build and restore natural carbon sinks like peatlands and soils – in other words, ‘conventional’ CDR.
Indeed, of the 139 protocols that have been recorded in total (between 2005 and mid-August 2025), 27% are attributable to afforestation, reforestation and forest management (A/R),15% to soil carbon sequestration (SCS) and 4% to peatland and wetland restoration. In terms of credit issuance, A/R accounts for 91% of all issued credits and SCS projects constitute another 7%.
The MRV ecosystem developed fast between 2021 and 2024. In 2024 (the last full year), 23 MRV protocols were published, which was a small increase on the total of 20 in 2023. Protocol development in 2024 skewed slightly towards biochar methods and A/R, which saw four new protocols each. Overall, the data from 2024 indicate balanced MRV development with new protocols developed for 13 different CDR methods, the greatest range of methods to date. That said, the vast majority have been developed for novel CDR methods (17 of the 23).
Data from 2025 indicates slightly slower protocol development, with 15 protocols across 11 different methods being published to date. This recent protocol development is fairly balanced across methods, with two protocols each developed for A/R, direct ocean capture, alkalinity enhancement and one each for BECCS, DACCS, mineralisation, peatland restoration and marine biomass sinking. 2025 may reverse a pattern of annual year-on-year increases (since 2020) in terms of the total number of MRV protocols published.
Although we observe a complex system with duplication and annual increases in MRV protocol development, the majority of issuance is still occurring through a few select protocols. For example, for coastal wetland restoration, Verra's VM0033 protocol is responsible for 99% of issuance. For soil carbon sequestration, three protocols account for 78% of all issued credits, with Verra's VM0032 and VM0026 respectively accounting for 24% and 23% of total issuance and Plan Vivo accounting for 31%. For A/R, 88% of issued credits stem from just four protocols, with the California Air Resources Board's Compliance Offset Protocol U.S accounting for 72% of all A/R issuance.
Biochar is a slight outlier, as nearly all existing protocols (7 out of 9) are actively issuing credits. However, two protocols—Carbon Standards International and Puro—still dominate the space, accounting for 54% and 40% of the 1.2 million total credits issued, respectively.
This clustering suggests that improvements to the small number of dominant standards could have positive but disproportionate impacts on the issuance market. On the other hand, if the efficacy of the protocols becomes diluted over time, there is the possibility of a systemic risk: any inadequacies in a dominant standard could have ripple effects on large swathes of the market. Scrutinising the dominant protocols is therefore a governance priority.
One more surprising insight, given that MRV development for CDR methods is primarily happening in the voluntary carbon market, is the major role of compliance markets. Just over 70% of credits issued can be used in compliance markets, most significantly within the California Air Resources Board programme. However, outside California and in terms of novel durable CDR, there is virtually no issuance in compliance markets yet. As more compliance markets such as the UK emissions trading system (ETS), the EU ETS and the Japanese GX-ETS allow CDR credits to be used for compliance purposes, we will see greater issuance in these markets.
In addition, with Singapore recently signing contracts for carbon credits from A/R projects, including projects under VM0047, this may also become an eligible protocol for compliance purposes under their domestic carbon tax.
The latest iteration of TRACEcdr contains preliminary high-level analysis on the type of lifecycle assessment (LCA) – either consequential or attributional (cLCA/aLCA) – used. For a detailed methodology see this page.
Attributional LCA considers a project’s supply chain emissions to be static and allocates removals (and emissions) to the project usually with default values. Attributional accounting is typically used to produce an ‘inventory of emissions’ such as a national or corporate greenhouse gas inventory that records emissions/removals over time.
Consequential LCA, on the other hand, sheds light on the change in emissions a CDR project creates at a systemic level, for example by using counterfactual scenarios to model changes in energy system emissions arising from increased energy demand from a CDR project.
We find that only 34 of 121 (24%) analysed protocols have predominantly ‘consequential’ characteristics. How significant is this?
There are different schools of thought regarding the relative benefits and use cases of attributional and consequential LCA. A recent piece by Goldsworthy (2025) discusses the relative merits. Consequential LCA has been widely used because of its close alignment with the concept of ‘additionality’ – i.e. the extent to which greenhouse gas emission reductions or removals would have occurred in the absence of the associated policy intervention or activity – and its focus on system-wide effects.
However, Goldsworthy criticises consequential LCA for lacking the standardisation critical for markets to scale up, its vulnerability to over-crediting – i.e. the risk that more credits than tonnes of CO₂ removed are issued by a given project, and the difficulty in reconciling outputs with inventory-based emissions reporting (i.e. comparing and validating estimates of greenhouse gas emissions derived from different methodologies). Attributional LCA, by contrast, aligns more closely with inventory reporting, but is a blunter approach because of co-product emission allocation along the value chain (i.e. dividing the greenhouse gas emissions of a shared process among its multiple outputs may be missed).
While attributional accounting plays a critical role in recording and tallying an entity's emissions and transition progress, this approach, when applied to a CDR project may not provide the depth of information required to understand the project’s wider impacts and whether it is delivering net removals.
A real-world example where an attributional or consequential approach would yield different answers is provided by Brander (2021), who describes how both approaches have been taken in the Scottish whisky industry. This industry has: “…started using the grain residues from its distilling processes as a fuel because it substitutes for their use of fossil fuels. With this change in fuels, the GHG emissions reported in their corporate GHG inventories decrease.” This would be the outcome of an attributional approach. However, a consequential approach would take into account the following: “livestock farmers who previously used the grain residues as animal feed now have to buy more soy meal, which increases the cultivation of soy and contributes to deforestation in countries expanding their agricultural output” (p2-3).
Overall, as consequential LCA is larger in scope, theoretically it provides a better understanding of systemic implications. Where diverse supply chains exist, consequential LCA approaches may be better placed to capture any land use changes that emit carbon or impact food supply, e.g. in the case of BECCS, or supply chain emissions for minerals affecting enhanced rock weathering (ERW). Yet our analysis shows that only 17% of BECCS protocols and 20% of ERW protocols are consequential and, concerningly, leakage is not considered in any of the BECCS protocols reviewed and in only 40% of ERW protocols (market leakage can occur if the shift in activity causes emissions to increase across regional or sectoral systems).
With governments increasingly looking to develop bespoke protocols to integrate these removals into policy architectures, particularly in a way that adheres to high levels of environmental stringency, it will be interesting to see whether they converge around consequential LCA or attributional LCA perspectives.
TRACEcdr also provides insights into how protocols deal with critical issues such as additionality (see above), permanence (i.e. the risk of stored CO2 being re-released into the atmosphere is explicitly modelled and discounted within the carbon accounting itself), leakage (see above) and baseline setting (setting a reference state or the values against which we measure change) – see Table 1.
Despite the dominance of conventional MRV protocols, the majority of protocol development over the last few years has been for novel methods that incorporate increasingly stringent accounting attributes. For example, of the new protocols developed in 2024, 57% had predominantly cLCA attributes compared to just 5% of protocols developed in 2022.
When reviewing the results for additionality, the proportions of MRV protocols for novel methods were generally higher than conventional methods, with the exception of BECCS (17%) and durable wood products, where there were no assessments of additionality. Similar results can be seen with baseline definitions across MRV for novel CDR compared with conventional CDR. Indeed, biomass burial, for which the first protocol was only developed in 2023, is the only method (out of those with more than one protocol) where all protocols are consequential and attempt to address leakage, permanence, additionality and baselines challenges.
As our understanding of carbon accounting grows and new evidence emerges, what constitutes best-practice MRV will also evolve. So far this has proven to be true. Earlier iterations (i.e. in the 2010s) may not have required the stringent leakage and permanence tests that are commonplace in 2025. Therefore, assessments of MRV protocols by buyers or policymakers should also take into account the year of publication and whether they include the latest guidance.
An intra-protocol comparison is provided in Table 2. The Protocol Explorer tab within the tool allows users to explore at a granular level how the specific protocols were classified against the criteria in Table 1.
Over the coming months we will be publishing additional analysis and guest content from TRACEcdr. If you would like to collaborate with us, please get in touch!
