8:~~~n
II Microsoft
2023 EDITION

Criteria for HighQuality Carbon
Dioxide Removal

Table of Contents
Introduction

03

Essential Principles forHigh-Quality Carbon Removal

06

Forestation and Agroforestry

13

Mangrove Forestation

19

Improved Forest Management (IFM)

26

Soil Carbon

31

Enhanced Rock Weathering(ERW) in Croplands

36

Carbon Mineralization

41

Biomass-based pathways

46

Direct Air Capture

52

Conclusion

58

Criteria for High-Quality Carbon Dioxide Removal

2Introduction
The science is clear. Ambitious action is needed to reduce greenhouse gas (GHG)
emissions while also rapidly scaling carbon dioxide removal (CDR). Effective and equitableclimate action can both reduce climate loss and damage and provide wider benefits tosociety. The AR6 WIII report from the Intergovernmental Panel on Climate Change (IPCC)
estimates the global community must remove 100-1000 billion metric tons of carbon
dioxide (GtCO2) by 2100 to limit warming to no more than 1.5°C. To reach this goal, largescale CDR projects must annually remove 5-10 GtCO2 by midcentury. Achieving this goal
will require rapid scale-up and deployment of all viable CDR methods.
Microsoft and Carbon Direct are committed to the development of this critical market.

~ Carbon Direct
Carbon Direct helps organizations go from climate goal to climate action. Carbon Direct
combines technology with deep expertise in climate science, policy, and carbon markets todeliver carbon emission footprints, actionable reduction strategies, and high-quality CDR.
With Carbon Direct, clients can set and equitably deliver on their climate commitments,
streamline compliance, and manage risk through transparency and scientific credibility.

1■ Microsoft
Microsoft is committed to be carbon negative by 2030. This means that Microsoft will cut
annual GHG emissions by more than half and remove all remaining annual emissions. By
2050, Microsoft also commits to remove the equivalent of all cumulative GHGs emitted
since Microsoft was founded. In January 2021, Microsoft announced its first portfolio of 1.3
million metric tons of CDR. In March 2022, Microsoft announced an additional 1.5 million
metric tons added to its CDR portfolio.

The information in this document represents the current view of Microsoft and Carbon Direct on the content.
It is for informational purposes only. MICROSOFT AND CARBON DIRECT MAKE NO WARRANTIES, EXPRESS,IMPLIED, OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.

Criteria for High-Quality Carbon Dioxide Removal

3

Over the past three years, Microsoft and Carbon Direct observed a critical challenge inthe emerging CDR industry: while there are many CDR projects on the market, few meet
our criteria for high quality. A major contributing factor to this challenge is that CDR
project developers and purchasers lack a common framework for determining what
constitutes a best-in-class project. Microsoft elaborated on the need for a common
framework in the January 2021 whitepaper, noting the need for clear carbon accounting
standards and the development of rigorous guidelines for additionality, durability, andleakage. Microsoft updated these findings in the March 2022 whitepaper, where we
discuss the lack of common standards, high prices, and insufficient supply of highquality CDR credits.
Recent policy announcements also highlight the pressing need for evidence-based CDR
criteria to guide action by both public- and private-sector actors. In the US, government
entities — including the Securities and Exchange Commission and the Federal
Acquisition Regulatory Council — have proposed new rules on climate risk disclosure.
The Inflation Reduction Act and the Infrastructure Investment and Jobs Act provide newfunding for CDR project development. And globally, as of May 2023, 62 countries havesubmitted long-term strategies to the UN Framework Convention on Climate Change(UNFCCC), many of which include nature-based and engineered CDR in CO2 emissions
reduction strategies. Together, these developments underscore the urgency for just,scientifically grounded CDR principles that ensure effective climate action acrosssectors and borders.
To help rapidly scale high-quality CDR, we developed the inaugural Criteria for HighQuality Carbon Dioxide Removal in 2021. This 2023 update is intended to achieve two
key objectives:

01 First, the updated criteria should support and guide submissions to
Microsoft for CDR procurement.
02 Second, and more broadly, the updated criteria should help advance acommon definition of high-quality CDR by providing widely applicablequality benchmarks. We hope to catalyze CDR market maturation thatfacilitates just, effective climate action at scale.

Criteria for High-Quality Carbon Dioxide Removal

4

We emphasize that the following criteria are not a substitute for pre-purchase due
diligence to demonstrate scientific efficacy and validation. Nor are they intended toreplace existing industry standards, which provide important, though in some cases
imperfect or underdeveloped, quality assurance. We encourage existing standardsetting bodies to consider how these criteria could inform their protocols and principles.
The science of CDR is evolving, and these criteria will progress with this evolution. The
2023 edition provides updates across the essential principles as well as each of the CDR
methods, including new criteria for enhanced rock weathering (ERW). This document
also aims to center guidance on how to incorporate the tenets of environmental justiceinto CDR projects, with an emphasis on procedural equity1 and the equitable distributionof harms and benefits. In subsequent iterations, we expect to develop additional
guidance for nascent CDR pathways, potentially including macroalgae cultivation,
peatland and freshwater wetland restoration, carbon dioxide utilization, and ocean
alkalinity enhancement. We look forward to collaboratively refining this guidance overthe coming years.

As defined by the IPCC, procedural equity is “equity in the process of decision-making, including
recognition and inclusiveness in participation, equal representation, bargaining power, voice and equitable
access to knowledge and resources to participate.”
1

Criteria for High-Quality Carbon Dioxide Removal

5

ESSENTIAL PRINCIPLES FOR

High-Quality Carbon
Dioxide Removal
The following common set of shared principles are intended to help characterize highquality CDR projects. Note we distinguish between principles that “must” or “should”
be considered during project development and implementation. We use these terms
to differentiate between minimum viable project characteristics (must) versus ideal
project characteristics (should). These principles are not exhaustive but are intended todescribe key considerations across all CDR pathways.
A “project” is a cohesive set of activities that are relevant to generating CDR credits. In
some cases, CDR activities may be a part or extension of a larger body of activity. For
these cases, the “project” refers to the component that is relevant to generating CDR
credits. CDR developers and buyers typically evaluate the quality of individual projects. It
is also important to consider potential environmental, social, and other impacts across a
CDR portfolio. While impacts of individual projects are often relatively small, collective
impacts from each CDR pathway at scale may be significant.
The principles for specific CDR pathways build upon the common principles
described below.

0 Harms and benefits
Minimizing harms involves avoiding negative impacts on economic, social, andenvironmental systems that result from CDR projects. Because concerns vary by CDR
pathway and context, the harms that follow are not exhaustive, but are intended todescribe some of the common negative impacts across all CDR pathways.

Criteria for High-Quality Carbon Dioxide Removal

6

Beyond avoiding harm, projects can maximize benefits to local communities andecosystems by advancing environmental justice (see below), building climate resilience,
supporting alternative livelihoods, and protecting ecosystems and biodiversity.
PROJECT DEVELOPERS MUST•Show that projects have a low risk of community health impacts and provide astrategy for mitigating any such health risks.

•

Assess the likelihood and severity of project activities negatively impacting
surrounding ecosystems (including but not limited to soil health, biodiversity, andwater resources) and provide a mitigation strategy.

•

Assess the likelihood and severity of project activities negatively impacting local
communities (including but not limited to increased risk of wildfire, food insecurity,
energy unaffordability) and provide a mitigation strategy.

•

Prevent community displacement.

•

Transparently report any use of toxic and/or persistent environmental pollutants,
including agrochemicals.

•

Avoid using pesticides banned in the United States or European Union.

Environmental justiceEnvironmental justice involves equitable distribution of environmental benefits
and harms resulting from CDR project development, implementation, and ongoing
MRV. Environmentally-just CDR projects empower local communities by facilitating
meaningful participation throughout the CDR project lifecycle. Inclusive, accessible, andauthentic community engagement includes centering perspectives from vulnerable or
marginalized community members. This collaboration and/or shared project leadership
starts by acknowledging past and present harms to communities of color, low-income
communities, and other vulnerable communities affected by intersecting climate andracial injustice crises.

Criteria for High-Quality Carbon Dioxide Removal

7

PROJECT DEVELOPERS MUST•Show how they directly, transparently, and periodically engage with local
communities throughout the project lifetime.

•

Inform local communities through ‘outreach’ as defined by the ATSDR community
engagement continuum for evaluating procedural equity.

•

Explicitly describe worker compensation in project proposals and commit to pay aliving wage at minimum.

•

Ensure local communities that may have a stake in project lands, including
Indigenous groups, are actively engaged and represented in project processes
throughout the project lifetime.

PROJECT DEVELOPERS SHOULD•

Actively involve community members during project development, implementation,and subsequent monitoring (see the ATSDR community engagement continuum as areference for evaluating procedural equity).

•

Clearly articulate how the project will benefit underserved and marginalized
populations, generate wealth and economic empowerment, and/or foster community
involvement across the lifetime of the project.

•

Ensure project benefits accrue to members of the local community, especiallyvulnerable and marginalized populations, and communicate these benefits tocommunity members.

•

Prioritize community needs and priorities when designing and implementing CDR
projects.

•

Delineate the percentage of project revenues or profits paid to community members
and other local partners, the form of these payments (for example, cash payments,
in kind payments, or funding for community services), and the timing of thesepayments.

•

Avoid developing or disturbing land designated as culturally sensitive or ecologicallyimportant by community members or local stakeholders.

•

Make public carbon reduction targets and clean energy transition commitments.

Criteria for High-Quality Carbon Dioxide Removal

8Additionality and baselines
Removals are additional if they would not have occurred without carbon finance. The
baseline of a project is a conservative estimate of the carbon and other GHG
impacts that would have occurred without carbon finance (the “counterfactual”).
PROJECT DEVELOPERS MUST•Show that they require carbon finance to implement the project.
•

When there are multiple finance streams supporting a project, projects are
considered additional if revenue from the sale of carbon credits is required toinitiate project activities.

•

Show that the project is not required by existing laws, regulations, or other binding
obligations.

•Show that project activities are not “common practice,” even in the absence offinancial or regulatory incentives.

•

Quantify the removals claimed relative to the most plausible baseline for carbon
stocks and flows, i.e., the counterfactual in the absence of carbon finance.
•Baselines must account for both recent and projected changes in carbon andother GHG stocks and flows.

•

Baselines must be conservative and site specific.

PROJECT DEVELOPERS SHOULD•

Provide full project financial information to demonstrate financial additionality,
particularly where multiple revenue streams are present.

Carbon accounting & Monitoring, reportingand verification (MRV)
Project-level carbon accounting reports all greenhouse gas emissions associated with a
CDR project using repeatable and verifiable GHG quantification methods. In general, thisCriteria for High-Quality Carbon Dioxide Removal

9requires the use of cradle-to-grave life cycle assessments (LCAs) and/or models that
accurately estimate CDR, calibrated by periodic direct measurement.
Monitoring, reporting, and verification (MRV) involves developing and adhering to aplan for long-term monitoring of the project. Carbon accounting and MRV are often
closely linked. Developers should consider the interactions between these two criteria
during project planning and execution.
PROJECT DEVELOPERS MUST•

Develop a credible MRV plan prior to the start of the project.

•

Adapt the MRV plan throughout the project by incorporating the best available
science and evolving industry practices.

•

Use peer-reviewed and scientifically supported carbon accounting methods toquantify the net volume of removals claimed, and disclose the specific methods
used.

•

Where an LCA is provided, use a cradle-to-grave LCA and specify the use of either
attributional or consequential LCA.

•

Incorporate uncertainty conservatively to avoid overstating the estimated CDR froma project.

•

Separately quantify removed, reduced, and avoided emissions, including delineatingby greenhouse gas type.

•

If applicable, use models that are calibrated and validated for the specific conditions
in which the project will operate.

•

If applicable, specify model assumptions that cannot be calibrated or revised due topractice constraints. Developers should periodically review MRV measurements andother scientific advancements to revise all other assumptions.

PROJECT DEVELOPERS SHOULD•

Use regionally appropriate sampling and data collection methods to quantify
emissions and removals associated with a project instead of solely model-based or
statistical methods.

•

Ensure that the project’s MRV plan is certified or endorsed by a third party (e.g., via aregistry).

Criteria for High-Quality Carbon Dioxide Removal

10

•Obtain third-party verification of calculated net removal volumes (e.g., via a registry).

•

Directly measure carbon removed and stored throughout the duration of the project tothe maximum practical extent possible. Store this data in a shared repository or
facilitate data access to advance CDR MRV and accelerate market development.

Durability
Durability is the capacity for stored carbon to withstand reversal, or re-emission, to theatmosphere. We use the term “durability” because it is less absolute than “permanence”
and acknowledges the temporal variability inherent to most forms of carbon storage.
The durability of stored carbon is limited by both natural and anthropogenic risksof reversal, which can prematurely release carbon from storage. Reversals can beeither intentional (e.g., changing management practices) or unintentional (e.g., natural
disturbances). Longer and more durable storage terms are preferable (until widely
accepted methods enable comparison of varied durability terms). We use the term
“durability” because it is less absolute than “permanence” and acknowledges the
temporal variability inherent to most forms of carbon storage.
PROJECT DEVELOPERS MUST•

Provide a projected duration (in years) over which removed carbon will be stored.

•

Implement an MRV plan to monitor the stored carbon and reliably detect reversal events.

•

Conservatively estimate a project’s risk of reversal using the best available science,
including planning for present and future climate change.

•

Identify who is liable for remediating the reversal of stored carbon and the length of thisliability (e.g., number of years).

PROJECT DEVELOPERS SHOULD•

Site projects in areas with low risk of reversal and implement ongoing risk mitigation
measures to minimize the impact of future reversal events, including future risks
associated with climate change.

Criteria for High-Quality Carbon Dioxide Removal

11•

Ensure that agreements during project execution include measures that mitigate therisk of reversals throughout and beyond the project operational lifetime.

•

Rely on insurance-type products, such as a buffer pool, to address the risk ofreversal, which:•Reflect a scientifically substantiated, conservative risk of reversal, including
possible increases in risks associated with climate change.

•

Dictate that intentional reversals must be entirely remediated, even exceeding all
buffer pool contributions from the project.

•

Retire a project’s buffer pool credit contributions at the end of the project’s life.

LeakageEconomic leakage (“leakage”) is the displacement of GHG emissions from the projectsite to another geographic location. Economic leakage typically occurs because market
demand for the output of the emitting activity is unchanged, while the CDR projectdecreases local supply. Leakage should not be confused with physical leakage of stored
CO2, which is discussed in the Durability principle.
There are two forms of economic leakage: activity-shifting and market. Activity-shiftingleakage occurs when agents operating within a project boundary shift production
outside the project boundary. Market leakage occurs when a project reduces the
production of a good, and this local reduction induces increased production of that good
elsewhere to meet demand. Market leakage can be very difficult to predict and measure.
PROJECT DEVELOPERS MUST•

Conservatively account for the carbon impacts of leakage caused by the project orconclusively demonstrate the project avoids any leakage.

PROJECT DEVELOPERS SHOULD•

Diminish leakage risk in project design.

Criteria for High-Quality Carbon Dioxide Removal

12

NATURE-BASED

Forestation &Agroforestry
Forestation, including reforestation and afforestation, is the process of growing trees
to establish forests or woodlands. Agroforestry integrates trees within agriculture
production systems. Improved forest management (IFM) and mangrove forestation are
included as separate sections below.
Given the large amount of degraded land globally, forestation and agroforestry offer
substantial opportunities to remove carbon from the atmosphere while simultaneously
providing essential co-benefits to communities and nature. Given the complex andplace-based social, ecological, and economic dynamics of land use, developers shouldsite projects where socially or environmentally appropriate. The following principles
for forestation and agroforestry projects build upon those described previously under
Essential principles for high-quality carbon dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Avoid project development on land with unclear or insecure land tenure to reduce the riskof tenure disputes and disenfranchisement of local communities.

•

Avoid violence when establishing or protecting forested areas.

Criteria for High-Quality Carbon Dioxide Removal

13

PROJECT DEVELOPERS SHOULD•

Prioritize biodiversity and resilience by growing diverse native species, pursuing
ecological restoration or natural regeneration of formerly forested areas where
possible, and choosing species and seedling sources which maximize biodiversity
and are capable of flourishing under future local climatic conditions.

•

Prioritize local seed stock collection methods that do not harm natural forests or
reduce production of non-timber forest products and utilizes local infrastructure andseed supply chains (per Kew’s 10 Golden Rules for Reforestation).

•

Expand the volume of seeds available to ensure adequate supply for pre-existing
demand as well as accommodate increased demand from new CDR project activity.

•

Consider the impacts on biodiversity (both benefits and costs) when selecting
species for forestation.

Environmental justice
These criteria build on and extend the environmental justice considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Respect local or traditional approaches to land ownership and management.

•

Avoid project development on land with unclear or insecure land tenure to reduce the riskof tenure disputes and disenfranchisement of local communities.

PROJECT DEVELOPERS SHOULD•

Proactively plan for the job security and economic stability of workers to mitigate theshort duration of many forestation activities, e.g., through longer-term employment
across multiple parcels in a region.

•

Where displacement of existing activities occurs, even activities that may be deemed
destructive or illicit, ensure alternative livelihoods substitute for the displaced activities.

•

Actively promote long-term sustainable livelihoods and economic opportunities for local
communities (e.g., support local workforce development programs and initiatives).

Criteria for High-Quality Carbon Dioxide Removal

14

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Determine the natural regeneration baseline using the best available science to predict
natural seedling establishment and forest growth in the absence of tree planting.

•

Avoid damaging, destroying, or harvesting pre-project trees during site preparation.

•

Ensure pre-project trees are excluded from crediting and monitored through the crediting
period.

•Demonstrate that forestation or agroforestry activities are a result of carbon finance or
could not occur otherwise (for projects with non-carbon finance streams, such as fromexpected timber sales or conservation funds).

PROJECT DEVELOPERS SHOULD•

Establish control plots to directly measure natural regeneration or other growth incomparable parts of the surrounding landscape over the course of the project.

•

Use historical time series of remote-sensed data sufficient to show that natural
recovery of forest is very unlikely to occur when claiming a negligible naturalregeneration baseline.

•

Use a crediting approach that adjusts dynamically if legal compliance or other landuse dynamics change over time, especially where the project area is legally supposed
to be forested, but it is generally not, or there is otherwise uncertainty about evolving
land use.

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations
included under Essential principles for high-quality carbon dioxide removal.

Criteria for High-Quality Carbon Dioxide Removal

15

PROJECT DEVELOPERS MUST•

Justify the models and assumptions used to quantify carbon accumulation in theabove-ground biomass, below-ground biomass and (when the pool is included)organic soil pools.

•

Specify key assumptions that materially-affect modeled carbon accumulation rates,
such as the geographic and environmental variables, species-specific allometricmodels, and expected seedling survival rates.

•

Use statistically valid sampling methods and best-available models (for example,
species-specific and region-specific allometric equations) for quantifying aboveground carbon.

•

Use data from in-situ sampling or conservative root:shoot ratios (that is, use smaller
ratios to mitigate uncertainty) to quantify changes in below-ground carbon, where
this pool is included.

•

Measure and monitor changes in soil carbon when claiming removals in soils, using
the criteria for high-quality soil carbon.

PROJECT DEVELOPERS SHOULD•

Use ground inventories whenever feasible to validate remotely sensed
measurements of above-ground biomass changes.

•

Use site-specific data and/or collect data needed to parametrize models used toestimate biomass changes (such as species-specific allometries and wood densities
measurements).

•

If soil carbon is not directly measured, establish projects on lands where the net
impact of forestation or agroforestry on soil carbon is expected to be positive (e.g.,degraded lands).

•

Quantify any GHG fluxes associated with site preparation including removal ofexisting vegetation. If GHG fluxes are determined to be de minimis, the project
developer should articulate why.

•

Include a life cycle assessment of harvested products for agroforestry and plantation
projects.

•

Account for applicable and appreciable indirect climate impacts. For example,
projects occurring in high altitude/latitude areas should account for changes inalbedo due to establishment of tree cover.

Criteria for High-Quality Carbon Dioxide Removal

16

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Take active and ongoing measures to mitigate identified risks (e.g., forest thinning in fireprone areas).

PROJECT DEVELOPERS SHOULD•

Use the best available information to forecast future risks of disturbance to planted
forests and situate projects in areas of lower risk. Salient disturbance risks include, but
are not limited to, direct and indirect impacts of climate change, drought, fire, insects,
disease, financial insolvency of the project operator, land theft, timber theft, and social
disturbances.

•

Use resilient plant material with appropriate genetic variability and provenance.

•

Where appropriate, select species adapted to future climate conditions and apply
planting patterns that foster resistance to disturbance.

•

Incorporate harvested timber or biomass into long-lived wood products, either
traditional (e.g., lumber, oriented strand board) or emerging (e.g., biochar, crosslaminated timber).

•

Encourage additional productive uses of land such as beekeeping, sustainable wood
production, and ecotourism to ensure that forests are protected and maintained over
time.

•

Leverage early-warning systems to detect and respond to reversals, particularly
wildfire.

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.

Criteria for High-Quality Carbon Dioxide Removal

17

PROJECT DEVELOPERS MUST•

Provide robust and conservative estimates of leakage rates and justify the methods
used to quantify the leakage rate.

•

Ensure proper accounting for leakage deductions. This includes quantifying leakage
when project activities displace any existing economic activities, and these existing
economic activities shift outside the project boundaries.

•

When claiming low leakage rates, provide evidence that project lands are degraded,have low economic value, or that project activities do not significantly displace
existing land uses. Evidence must show that either:•

There has been minimal agriculture land cover over the preceding decade, theproject is not sited in an area of active land cover change, and that the lands are
predicted to have low likelihood of future use for agriculture.

•

Tree planting is integrated into ongoing agricultural practices using sustainableagroforestry systems.

PROJECT DEVELOPERS SHOULD•

Use remotely sensed land use data to determine leakage estimates, especially whencoupled with models of land-use change.

•

Establish contractual agreements that prevent activity leakage.

Other considerations
PROJECT DEVELOPERS MUST•Work with experienced local partners to select project locations, species, and planting
approaches.

•

Pilot restoration in small plots before scaling when restoration is first-of-its kind locally.

•

Develop planting and monitoring plans to maximize the probability of tree survival
during the critical three- to five-year establishment phase, including physicalinfrastructure and human capacity considerations.

•Use cost-effective forestation techniques such as applied nucleation, direct seeding, or
assisted natural regeneration.

•Work to abide by Kew Gardens’ 10 Golden Rules for Reforestation.

Criteria for High-Quality Carbon Dioxide Removal

18

NATURE-BASEDMangroveforestation
Mangrove forestation, including reforestation and afforestation, involves growing trees
to establish mangrove forests. Carbon-dense mangrove forests exist along the intertidal
zones of most tropical and subtropical coastlines. Many of these mangrove forests are
threatened and have experienced historically high rates of deforestation. The uniqueecology of mangroves warrants different guidance from the forestation and agroforestry
guidelines provided above.
The carbon held in mangrove forests is commonly referred to as coastal blue carbon,
which also refers to carbon held in tidal marshes, seagrasses, and other coastal
ecosystems. Mangroves also generate substantial co-benefits for people and nature,such as storm surge protection and fish nursery support. Given the complex and placebased social, ecological, and economic dynamics of land use, developers should onlysite projects where socially and environmentally appropriate. The following principles for
mangrove forestation build upon those described previously under Essential principles
for high-quality carbon dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Avoid the destruction of non-vegetated coastal ecosystems, such as natural tidal mudflats,
which are important and threatened ecosystem types across the globe.

•

Avoid damaging, destroying, or harvesting any pre-project mangroves during site
preparation activities.

Criteria for High-Quality Carbon Dioxide Removal

19

•Prioritize mangrove restoration in areas that protect communities from storm surge,
prevent coastal erosion, and support fish nursery habitat.

•

Prioritize forestation of biodiverse mangroves by supporting natural regeneration
processes or planting a variety of native species that are resilient to current andfuture environmental conditions. Avoid planting monocultures of generalist species,
such as Rhizophora spp.

Environmental justice2]lThese criteria build on and extend the environmental justice considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Articulate the land tenure of the enrolled project areas, including community management
status.

•Avoid project development on land with unclear or insecure land tenure to reduce risk.
Mangroves commonly exist on public land with customary tenure, raising the risk of tenure
disputes and disenfranchisement of local communities.

•

Respect local or traditional approaches to land ownership and management.

PROJECT DEVELOPERS SHOULD•

Proactively plan for the job security and economic stability of workers to mitigate theshort duration of many forestation activities, e.g., through longer-term employment acrossmultiple parcels in a region.

•

Include alternative livelihood activities in projects to replace foregone aquaculture income
or nutrition if mangrove forestation reduces aquaculture production.

•

Actively promote long-term sustainable livelihoods and economic opportunities for local
communities (e.g., support local workforce development programs and initiatives).

Criteria for High-Quality Carbon Dioxide Removal

20

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Identify the human and/or environmental drivers of mangrove loss or degradation and plan
to mitigate these impacts in the future.

•

Ensure pre-project mangroves are excluded from crediting and their continued existence ismonitored throughout the project crediting period.

•

Determine the natural regeneration baseline using the best available science to predict
natural seedling establishment and forest growth in the absence of tree planting.

PROJECT DEVELOPERS SHOULD•

Demonstrate that mangrove forestation activities are a result of carbon finance or
could not occur otherwise (for projects with non-carbon finance streams, such as fromexpected timber sales or conservation funds).

•

Establish control plots to directly measure natural regeneration over the course of the
project.

•

Use historical time series of remotely sensed data when claiming a negligible naturalregeneration baseline to show that natural recovery of mangrove forest is very unlikely
to occur.

•Quantify baseline GHG fluxes and any GHG fluxes associated with site preparation orother changes in management strategy.

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations included
under Essential principles for high-quality carbon dioxide removal.

Criteria for High-Quality Carbon Dioxide Removal

21

PROJECT DEVELOPERS MUST•

Justify the models and assumptions used to quantify expected carbon
accumulation in the above-ground biomass, below-ground biomass, and organic
soil pools. Key determinants of carbon accumulation such as environmental settingof forestation areas (e.g., fringe vs. deltaic settings), species-specific allometries,and survival rates of seedlings must be included.

•

Use statistically valid sampling methods and best-available models (for example,
species- and region-specific allometric equations) for quantifying above-groundcarbon, including stratifying by site hydrogeomorphology (e.g., fringe vs. deltaic
settings).

•

Use data from in-situ sampling or conservative root:shoot ratios (that is, use
smaller ratios to mitigate uncertainty) to quantify changes in below-groundcarbon, where this pool is included.

•

Measure and monitor changes in soil carbon when claiming removals in soils, using
the criteria for high-quality soil carbon and stratifying by site hydrogeomorphology(i.e., project developers must rely on empirical site-level data or models, notdefault soil carbon factors).

•

Develop monitoring plans that account for changes in carbon stocks using
some or all of these approaches: mapping, remote-sensing, long-term field plotmeasurements, relative sediment elevation table methods, and/or field-validated
modeling.

PROJECT DEVELOPERS SHOULD•

Compare and justify expected carbon accumulation numbers against benchmark
figures, such as standing carbon stocks in proximal mature mangrove stands, global
maps of mangrove carbon, or meta-analyses of carbon accumulation in planted
mangroves from scientific literature.

•

Employ validated and regionally calibrated methods and/or use ground inventories tovalidate remotely sensed measurements of above-ground biomass changes.

•

Use site-specific data and/or collect data needed to parametrize models used toestimate biomass changes (such as species-specific allometries and wood density
measurements).

Criteria for High-Quality Carbon Dioxide Removal

22•

If soil carbon is not directly measured, establish projects on lands where thenet impact of forestation or agroforestry on soil carbon is most likely to be net
positive.

•

Quantify any GHG fluxes associated with site preparation including removal ofexisting vegetation. If applicable, explain why any GHG fluxes are expected to bede minimis.

•

Account for any indirect climate impacts, for example, methane emissions
potentially resulting from hydrologic restoration.

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Plant mangroves in appropriate locations where they are likely to persist and flourish.

•

Integrate projections of sea level rise when choosing sites for forestation.

•

Implement active and ongoing measures (i.e., adaptive management plans) to mitigate
identified risks to the durability of carbon held in mangrove forests (e.g., direct and indirect
impacts from sea level rise, storm surge, or watershed management).

•

Determine the hydrological status of the site and address any impacts to site hydrologythat might prevent successful mangrove forestation.

•

Identify and mitigate human drivers of mangrove loss throughout the project life.

PROJECT DEVELOPERS MUST•

Identify potential policy conflicts for long-term management of forests due to unclear
demarcations of intertidal zones and overlapping jurisdictions of national or local
governments (e.g., Ministry of Marine Resources and Ministry of Forests).

•

When initiating projects that involve harvesting, incorporate harvested biomass into longlived wood products, either traditional (such as lumber or polewood) or emerging (such as
biochar).

Criteria for High-Quality Carbon Dioxide Removal

23

•Plant species adapted to future climate conditions and apply planting patterns that
foster resistance to disturbance, including plans to mitigate “coastal squeeze,” i.e.,
the phenomenon by which mangroves cannot migrate landwards with sea level
rise due to impermeable surfaces such as paved urban areas.

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Provide robust and conservative estimates of leakage rates and defend the methods used
to determine the reported rate.

•

Ensure leakage deductions are taken and properly accounted for. Leakage should be
accounted for when project activities displace any existing economic activities that could
be shifted outside the project boundaries and result in higher emissions.

•

When claiming low leakage rates, provide evidence that project lands have low economic
value, or that project activities do not significantly displace existing land uses. They must
demonstrate this by showing that there has been minimal past agriculture or aquaculture
use over the preceding decade, they are not operating in an area of active land usechange, and that the lands are predicted to have low likelihood of future agriculture or
aquaculture land use.

PROJECT DEVELOPERS SHOULD•

Use remotely sensed land use data to determine leakage estimates, especially whencoupled with models of land-use change.

Criteria for High-Quality Carbon Dioxide Removal

24

Other considerations
PROJECT DEVELOPERS SHOULD•

Develop seedling planting and monitoring plans to maximize the probability of tree survival
during the critical three- to five-year establishment phase, including physical infrastructureand human capacity considerations.

•Use cost-effective and equitable forestation techniques such as Community-Based
Ecological Mangrove Restoration, or the engagement of local communities in removing
barriers to natural regeneration such that mangrove forests naturally return.

•Consider the impacts on biodiversity (both benefits and costs) when selecting species for
mangrove forestation.

•

Appropriately match species to positions in the intertidal zone and avoid planting solely
generalist mangrove species (e.g., Rhizophora species).

Criteria for High-Quality Carbon Dioxide Removal

25

NATURE-BASED

Improved Forest
Management (IFM)
Improved forest management (IFM) involves management changes that increase carbon
stocks in forests and in harvested wood products. IFM projects are hampered byuncertainty in project baselines, additionality, and market leakage. These uncertainties
make accurate quantification of CDR from IFM challenging and have tended to resultin overestimation of carbon benefits. Best-in-class IFM projects minimize uncertainty
and conservatively estimate carbon sequestration. The following principles for IFM
build upon those described previously under Essential principles for high-quality carbon
dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Transparently report any use of toxic and/or persistent environmental pollutants, including
agrochemicals used for suppression of non-crop plants.

•

Ensure that the project minimizes major risks to the health and safety of workers,
especially risks present in forest management operations.

Criteria for High-Quality Carbon Dioxide Removal

26

PROJECT DEVELOPERS SHOULD•

Implement forestry practices that are regionally appropriate and designed to foster
habitat for indicator species and encourage biodiversity broadly.

•

Prioritize IFM projects that support local and regional industry, livelihoods, and longterm sustainable forestry.

Environmental justice
These criteria build on and extend the environmental justice considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Ensure that when projects occur on public lands or communally owned or lands withcustomary tenure, and carbon rights are transferred to a third party, the benefits ofthe project are shared among members of the community by actively including land
stakeholders in planning, execution, and operation.

PROJECT DEVELOPERS SHOULD•

Avoid increasing natural disturbance hazards that may directly or indirectly impact
local communities.

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Reflect initial carbon stocks and trends in carbon stocks over at least the past decade orreflect typical management on similar parcels in the region.

Criteria for High-Quality Carbon Dioxide Removal27

•Are informed by previous forest management practices, as documented in previously
written management plans. In the absence of these plans, developers must provide
evidence that the baseline is realistic for the owner and property in question.

•

Account for recent or projected changes in forest product demand. For example, projects
located in regions with decreasing harvesting trends, such as those due to closed mills,
can be expected to have increasing baseline stocks.

•

Are project-specific, rather than relying on regional forest carbon stock averages.

PROJECT DEVELOPERS MUST•

For projects with multiple revenue streams, such as timber harvest or conservation
investments, demonstrate that IFM activities are unequivocally a result of carbon financeby documenting inputs to financial models (e.g., those used to calculate net-present
value).

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST USE THE BEST AVAILABLE TOOLS TO MEASURE AND
VERIFY CHANGES IN CARBON STORAGE, INCLUDING:•

Statistically representative field inventories and/or remote sensing.

•

Allometry based on published regional- and species-specific data.

•

Reporting carbon pools with increased storage only where data and measurements canbe well substantiated (for example, ignoring increases in soil carbon when uncertainty ishigh).

•

Reporting all carbon pools with decreased storage resulting from project activities.

WHEN USING SENSED DATA, PROJECT DEVELOPERS SHOULD•

Validate measurements with field inventories.

Criteria for High-Quality Carbon Dioxide Removal28

~ Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS SHOULD MAXIMIZE THE DURABILITY OF CARBON STORAGE BY:•

Improving forest health and reducing disturbance hazards (such as wildfire, insects,
drought) on project lands, including decreasing the risk of disturbance-induced mortality
associated with historical management practices such as fire suppression and adverse
species selection.

•

Designing projects that are on land with a lower natural reversal risk.

•

Incorporating harvested timber or biomass into long-lived wood products, either traditional(e.g., lumber, oriented strand board) or emerging (e.g., biochar, cross-laminated timber).

•

Including forward-looking projections of climate risk when accounting for reversal risks.

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

For projects that reduce timber harvesting, use conservative leakage assumptions, androbustly defend these estimates, accounting for domestic and international leakage.

•

Establish contractual agreements that prevent activity leakage.

PROJECT DEVELOPERS MUST•

Deduct market leakage at the same time as when increased stocks are credited, even if
existing offset protocols do not require this standard.

•

Design projects that minimize leakage risks by avoiding large reductions in harvested
wood products relative to the baseline.

Criteria for High-Quality Carbon Dioxide Removal

29

•

Ensure that leakage risks are properly quantified. Leakage risks are likely highest:•

In regions where mills are running at capacity due to high demand in wood productmarkets and timber supply is responsive to price changes.

•

In regions where large amounts of non-participating lands can produce similar timber
products.

•

Where the wood products that would otherwise be produced on the project lands arehighly substitutable.

Other considerations
Project types
PROJECT DEVELOPERS SHOULD•

Project developers should consider IFM project types that may be of higher quality,
including:•Forest restoration with little decrease in timber harvesting.

•

Reduced impact logging.

•

Increased stand productivity through better stand management (such as thinning).

•

Increased forest fiber utilization.

•

Extended rotation lengths on commercial timberland while employing very conservative
leakage rates.

Criteria for High-Quality Carbon Dioxide Removal

30

NATURE-BASED

Soil Carbon
Soil carbon CDR involves adoption of new conservation and/or regenerative agricultural
management practices that increase the amount of carbon stored in soil. These practicechanges can stem the substantial global loss of soil carbon2 and associated GHG
emissions resulting from the inception of human agriculture.
Agriculture both contributes to GHG emissions and is especially vulnerable to theimpacts of climate change. Soil carbon projects can minimize these adverse climatechange impacts by improving long-term sustainability and increasing the climate
resilience of agricultural operations. The following principles for rigorous and credible
soil carbon projects build upon those described previously under Essential principles forhigh-quality carbon dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•Show that projects have a low risk of community health or ecosystem impacts (e.g.,
negative impacts on air or water quality, land degradation, and/or sound pollution) fromchanging agricultural practices and inputs (fertilizer, herbicides, etc.).

•

Articulate a strategy for mitigation of impacts to air, water, and land quality from changes
in agricultural inputs (fertilizer, herbicide, etc.) or practices.

PROJECT DEVELOPERS SHOULD•

Account for farmers’ needs to adapt to future climate conditions in the development ofmanagement plans and contracts.

Criteria for High-Quality Carbon Dioxide Removal

31

Environmental justice
These criteria build on and extend the environmental justice considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Equitably distribute benefits resulting from improved soil health to all project participants,
including both landowners and operators.

•

Compensate workers with living wages and protect the health and welfare of farmlaborers.

•

Avoid developing, disturbing, or restricting access to land that has been identified asculturally sensitive or ecologically important by community stakeholders.

PROJECT DEVELOPERS SHOULD•

Design projects to accommodate participants who both own and lease land. Thisshould include provisions to ensure that lessees do not inadvertently experience
adverse financial effects by improving soil health through regenerative practices (i.e.,higher rent for more desirable land).

•Actively promote long-term sustainable livelihoods and economic opportunities for
local communities.

•

Specify what percentage of project revenues or profits are paid to farmers.

•

Make every effort to identify how the project labor will be distributed andcompensated as well as disclose that information in the project description,
considering that farming and ranching operations often rely on migrant labor.

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.

Criteria for High-Quality Carbon Dioxide Removal

32

PROJECT DEVELOPERS MUST•

Document baseline emissions from business-as-usual management using control plots tomeasure a baseline or at least three years of historical management and soil carbon data
to document baseline trends and inform modeled baselines.

•

Demonstrate that the new practice is not already a standard management practice acrossthe farm or ranch.

PROJECT DEVELOPERS SHOULD•

Use region-specific and agricultural system-specific baselines to quantify the change insoil carbon resulting from new management practice adoption.

•

Ensure that practices aimed at increasing soil carbon content account for any increases in

l::T1
l:U

other greenhouse gas emissions.

Carbon accounting and MRV

These criteria build on and extend the carbon accounting and MRV considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Account for project removals net of any material emissions increase, including increased
fertilizer applications.

•

Document sampling stratification by practice, soil type, crop, and other relevant
environmental factors.

•

Describe the analytical and calculation methods used to assess soil carbon change,
including the mass/depth basis and any correction applied.

•

Conduct project-specific soil sampling at project outset and at least once every five years
to validate modeled estimates of soil organic carbon levels; soil sampling must be viewed
as a necessary complement to modeling.

•

Take soil cores to a sufficient depth to represent the impact of the implemented practice(e.g., cover crops at a minimum of 30 cm depth below the organic layer, 1 m or soil depth
for some types of tillage change).

Criteria for High-Quality Carbon Dioxide Removal

33

•Calculate carbon content using an equivalent soil mass basis.

•

Use models that have been developed and published in peer-reviewed literature for a
specific soil/climate/management context.

•

Follow best practices to create confidence in model results, including appropriate methods
for model calibration and validation with region- and practice-appropriate independent
datasets and comprehensive assessment of model prediction uncertainty. Document
model procedures and validation data sources.

•

Account for both sampling error and model prediction uncertainty prior to issuing credits.

PROJECT DEVELOPERS SHOULD•

Take soil cores as deep as possible, ideally to one meter.

•

Use best laboratory analysis practices to measure carbon, such as dry combustion ina carbon and nitrogen (CN) analyzer.
•

Project developers may use novel technological approaches in addition to provenmethods for proof of concept; however, these methods should not replace soil
sample collection and analysis.

•

Provide comprehensive documentation of all soil carbon quantification methods thathave been reviewed by a qualified third party.

•

Share soil and management data to build a more robust global dataset. Farmer data
could be aggregated and anonymized to respect privacy.

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Provide a durability term supported by a detailed monitoring and verification
plan. The plan should monitor changes in management practices and subsequent
reversals across the entire project area.

Criteria for High-Quality Carbon Dioxide Removal

34

•

Account for verification methods and contracting mechanisms for ensuring new practices
are implemented and maintained when determining durability.

•

Demonstrate robust strategies for ensuring carbon remains sequestered, even in instancesof ownership changes or extreme weather events.

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Conservatively quantify leakage risks, including the impacts of reduced herd numbers orcrop yields.

Other considerations
Scalability
PROJECT DEVELOPERS SHOULD BE AWARE THAT•

While the on-farm implementation of management practices that sequester carbon in soils
is well understood, the precise impact on soil carbon stocks is dependent on site-specificconsiderations such as soil type, crop, and climate.

•

Soil carbon scalability depends on producer behavioral change.

Criteria for High-Quality Carbon Dioxide Removal

35

HYBRID

Enhanced Rock
Weathering (ERW)in Croplands
Enhanced rock weathering (ERW) in croplands involves spreading crushed silicate rocks
onto agricultural fields. As these silicates dissolve, they catalyze the conversion of CO2
into bicarbonate. This dissolved inorganic carbon drains through waterways to theocean, a durable carbon sink. Given the large volume of silicate rock and agriculturalland, ERW as a carbon removal method could rapidly scale. However, many silicatescontain heavy metals and contaminants that can accumulate at high concentrations inplant matter. Further, the end oceanic bicarbonate sink cannot be tracked or verified
empirically. Instead ERW MRV relies on complex models to estimate CDR.
To help minimize ERW quality concerns, developers should develop quality assurance
and control plans for mineral applications, clearly report empirical sampling plansin agricultural fields, and document model initialization, calibration, validation, anduncertainty estimation. The following principles for ERW build upon those described
previously under Essential principles for high-quality carbon dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Document and measure the impacts of silicate application on waterways.

•

Quantify the risk of asbestos exposure in the mineral amendment.

Criteria for High-Quality Carbon Dioxide Removal

36•Document and define safety protocols required for silicate application and the impacts on
local air quality.

•

Mitigate risks associated with heavy metals by clearly documenting ongoing quality
assurance and quality control processes for sampling and analyzing silicate materials,
soils, and plant matter grown on fields where silicate material has been applied.

•

Quantify heavy metal concentrations in mineral amendments through elemental analysis.

•

Use elemental analysis results as inputs to model the expected heavy metal dissolution
and accumulation in the environment.

PROJECT DEVELOPERS SHOULD•

Document the impacts of silicate application on yield, soil chemistry (organic carbon,
mineral nutrients) and agrochemical applications (lime, mineral fertilizer).

•

Preferentially use source materials that maximize net carbon removal (e.g., existing particle
size distribution does not require additional processing and is close to application sites).

Environmental justice
These criteria build on and extend the environmental justice considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Avoid contaminating drinking water supplies.

•

Specify any project revenues that accrue to the farmers and communities.

•

Use best practices to minimize adverse impacts to local air or water quality.

•

Notify local stakeholders if adverse local ecological impacts are expected following
application (e.g., air quality impacts from mineral application).

•

Avoid developing, disturbing, or restricting access to land that has been identified asculturally sensitive or ecologically important by community stakeholders.

Criteria for High-Quality Carbon Dioxide Removal

37

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Provide documentation of any revenue streams beyond carbon credits. This includes, forexample, sale of silicate materials for application on croplands as an alternative to lime.

•

Explain assumptions underlying the project baseline, including naturally occurring rates ofsilicate mineralization and initial carbonate mineral content.

PROJECT DEVELOPERS SHOULD•

Justify expectations of zero baseline emissions, including accounting for mineral andwaste handling waste requirements, initial carbonate mineral content, and ambient
carbonation.

•

Use control plots to measure the baseline weathering rate on agricultural land.

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Ensure that carbon removal claims are consistent with a net carbon-negative outcome
based on a cradle-to-grave life cycle assessment that includes silicate processing,transportation, application, and impact to other non-CO2 GHG sources.

•

Document the particle size and granularity of the material applied to cropland.

•

Include edaphic factors such as moisture, temperature, and pH in the target region inmodels of weathering rates.

•

Use model(s) that have previously been established in peer-reviewed literature and/or
other applications with third-party evaluation.

•

Document how modeling frameworks link biogeochemical and hydrological processes.

Criteria for High-Quality Carbon Dioxide Removal

38

•

Follow best practices for model use to create confidence in model results, including
the use of appropriate methods for model calibration and validation with appropriate
independent datasets for the variable of interest (carbon drawdown).
•

These practices have not yet been well defined for ERW. We suggest that project
developers use soil carbon protocols, which share many of the same proxy measurement
and modeling issues, as a reference for developing appropriate sampling plans andmodeling approaches.

•

Document model initialization assumptions and how model uncertainty will be incorporated
into conservative carbon removal estimates.

•

Estimate losses of carbon back to the atmosphere during transport from the soil column via
river networks to the ocean and estimate ultimate carbon storage efficiency.

•

Provide a particle size distribution and morphology profile for any material applied to the
soil.

•

Use direct measurements of multiple variables to ground-truth models wherever possible.

PROJECT DEVELOPERS SHOULD•

Use the best available measurement methods to evaluate changes in soil healthfollowing silicate application.

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Define the timeline of the expected reactions and subsequent transport of aqueous ions toocean storage.

•

List carbon release risk scenarios for both precipitated and dissolved carbon (these risks
should be reflected in monitoring, reporting, and verification plans).

Criteria for High-Quality Carbon Dioxide Removal

39

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS SHOULD•

Provide an elemental analysis that quantifies the amount of rare earth elements andcritical minerals in the mineral application to avoid diverting resources away from otherapplications, like the renewable energy supply chain.

•

Identify alternative uses of mineral waste and demonstrate best use in terms ofgreenhouse gas impact.

•

Evaluate and quantify the impact of the project on land use when project infrastructure
requires undisturbed or high-value land.

Criteria for High-Quality Carbon Dioxide Removal

40

ENGINEERED

CarbonMineralization
Carbon mineralization transforms atmospheric CO2 into minerals during a naturally
occurring reaction. The products of mineralization are carbonate minerals, the mostdurable method of storing carbon. Carbon mineralization binds carbon in rock in bothunderground (in-situ) and aboveground (ex-situ) sites. In-situ mineralization injects CO2
underground into rock formations capable of forming durable carbonate minerals.
Ex-situ mineralization uses aboveground reactors or industrial processes to produce
carbonate minerals. This mineralized carbon can be incorporated into building products
such as concrete. Further, some industrial feedstocks can adversely impact ecosystems
and communities unless repurposed for mineralization. The following principles forcarbon mineralization build upon those described previously under Essential principles
for high-quality carbon dioxide removal. For agricultural applications, please refer to thecriteria for enhanced rock weathering (ERW) in croplands.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Minimize risk of adverse impacts on ecosystems and communities (e.g., changes in water
quality, land use, and pollutant use).

Criteria for High-Quality Carbon Dioxide Removal

41

Environmental justice
These criteria build on and extend the environmental justice considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•Engage with local communities in an ongoing and transparent manner throughout the
project lifetime. In cases where the project leverages existing industrial operations, clearly
describe how engagement processes are expanded to include the CDR project.

PROJECT DEVELOPERS SHOULD•

Actively promote long-term sustainable livelihoods and economic opportunities for
local communities, including identifying and addressing where possible, historicalnegative economic impacts to local communities.

•

Where possible, remediate past negative environmental impacts on the community,
for example from historical mining operations.

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Include mass balance of carbon in all states (solid, liquid, and agas), metals that contributeto mineral carbonate formation, and alkalinity imported or exported from the projectboundaries when quantifying project baselines and changes in mineralization rates.

•

Account for the rate of natural mineralization when calculating the project baseline.

•

Quantify the carbonate mineral content in feedstocks.

PROJECT DEVELOPERS SHOULD•

Select feedstocks with low carbonate mineral concentrations to reduce uncertainty incarbon accounting.

Criteria for High-Quality Carbon Dioxide Removal

42

•

Monitor feedstock carbonate mineral content throughout the project duration.

•

Develop control plots to measure natural rates of mineralization before, during, and after

EU'="=T1project deployment when relevant.

Carbon accounting and MRV

These criteria build on and extend the carbon accounting and MRV considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•Use best available measurement methods with built-in redundancy to directly measurecarbon contents and fluxes.

•

Use a cradle-to-grave LCA and specify the use of attributional or consequential LCA. The
LCA must conservatively quantify all GHG emissions associated with the full suite of inputs
and products from the project.

•

Use a cradle-to-grave LCA and specify the use of attributional or consequential LCA. The
LCA must conservatively quantify all GHG emissions associated with the full suite of inputs
and products from the project.

•

Evaluate and monitor, where appropriate, the impact of the project on other GHG pathways(such as methanogenesis, N-cycle).

•

Supplement and calibrate modeling with direct physical and/or chemical evidence ofmineralization.

PROJECT DEVELOPERS SHOULD•

Identify all carbon reservoirs and monitor carbon movement between reservoirs withappropriate tools (e.g., tracer, isotopic studies).

•

Use cost and life cycle assessments that clearly identify and differentiate
continuously produced and stockpiled industrial feedstocks.

•

Include cross verification with redundancy (e.g., cross referencing gas / liquid / solid
phase fluxes and mass balances).

•

Identify the source of metals (such as calcium, magnesium) contributing to mineralformation, and include in MRV the carbon impact of the metal source.

Criteria for High-Quality Carbon Dioxide Removal43

~ Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Consider reversal risks for both solid- and liquid-bound carbon and include these risks in
MRV plans.

•

Develop release scenarios that reflect anticipated impacts of climate change and changes
in land use or water reservoir development when relevant.

Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Identify alternative uses of waste and demonstrate best use in minimizing environmental
and climate impacts.

•

Evaluate and quantify the impact of the project on land use, especially when project
infrastructure encroaches on high-value land use.

Other considerations
Infrastructure
PROJECT DEVELOPERS SHOULD BE AWARE THAT•

Project infrastructure needs will depend on existing operations. Some ex-situ projects may
be greenfield developments, requiring new roads, ports, or facilities. Some in-situ projects
may require substantial infrastructure to capture or compress air or CO2.

Criteria for High-Quality Carbon Dioxide Removal

44

Scalability
PROJECT DEVELOPERS SHOULD•

Consider the size and distance to market or area of application for projects in the built
environment.

•

Account for changes in mineralization reaction rates over time due to consumption ofhighly reactive material and passivation of feedstock.

•

Consider feedstock supply and/or subsurface reservoir capacity and injectivity whenplanning large-scale mineralization projects.

Criteria for High-Quality Carbon Dioxide Removal

45

HYBRID

Biomass-based
pathways
Biomass-based pathways for CDR involve a range of processes that convert CO2
sequestered through photosynthesis into durable forms of carbon storage. Prominent
pathways include biochar, wood harvesting and storage, and geologic sequestrationof biogenic CO2 (e.g., BECCS).
These biomass carbon removal and storage (BiCRS) technologies can result in sizable
and highly durable CDR. Some pathways may also generate a co-product such as
electricity or hydrogen. The feedstock for biomass-based CDR can be grown directly
for CDR projects or can be a byproduct of other uses (such as forest or agriculturalresidues). The following principles for biomass-based CDR build upon those described
previously under Essential principles for high-quality carbon dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•Show that feedstock production, biomass conversion, and carbon disposal operations
have a low risk of any major negative impacts on the surrounding ecosystems (including
soil health, biodiversity, water, criteria air pollution) or local communities.

•

Develop and share a strategy for mitigation of adverse impacts to air, water, and land
quality, including those impacts related to biomass processing and storage.

•

Transparently report any use of toxic and/or persistent environmental pollutants, including
agrochemicals used in the production of purpose-grown feedstock.

Criteria for High-Quality Carbon Dioxide Removal

46

Environmental justice
These criteria build on and extend the environmental justice considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Prevent community displacement when selecting facility location.

PROJECT DEVELOPERS SHOULD•

Actively promote long-term sustainable livelihoods and economic opportunities for local
communities, by developing local and regional biomass-based CDR expertise.

•

Explore how project activities (e.g., feedstock production and product/co-product sales)
can benefit under-resourced and marginalized populations, including wealth generationand economic empowerment.

Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Identify the current use, if any, or other fate of biomass resources intended for the project.

•

Identify the most likely counterfactual for biomass resources in question over the length ofthe project (see Biomass sustainability section below).

•

Explain the economic additionality of the project with or without the requested investment
and/or CDR procurement, and the role of tax, regulation, or policy incentives (for example,
in the United States 45Q, Clean Fuel Standards, and the Inflation Reduction Act) in that
viability.

Criteria for High-Quality Carbon Dioxide Removal

47

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Ensure that CDR claims are consistent with a net carbon negative outcome based ona cradle-to-grave life cycle assessment (LCA), including biomass feedstock, process
emissions, and product transportation.

•

For waste feedstocks, provide detailed accounting and justification of counterfactuals.

•

Implement guidance for MRV listed under Process-specific considerations (below).

PROJECT DEVELOPERS SHOULD•

Conduct both attributional and consequential life cycle assessments.

•

Adjust carbon accounting to reflect trends in forest carbon stocks over time in the project
feedstock sourcing woodshed where forest biomass is used.

•

Clearly outline allocation methods for co-products, including a sensitivity analysis on
allocation assumptions and different scenarios employed.

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Create storage sites that are as permanent as possible using established permitting
processes (e.g., Class Ia, Class II, or Class VI for deep injection wells in the United States)or alternatively meet ISO 27914:2017 standard for CO2 storage.

PROJECT DEVELOPERS MUST•

Quantify and report expected changes in the amount of carbon sequestered over time,e.g., through decay or leakage.

•

Base durability projections on empirical measurements, rather than models, wheneverpossible.

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Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Quantify the likely carbon emissions that result from project consumption or displacementof local and regional energy supplies (e.g., parasitic load for capture and compression of
CO2.)

PROJECT DEVELOPERS SHOULD•

Avoid relying on feedstock to CDR with potential land-use change impacts or bioeconomy
product supply impacts (i.e., by following the guidance on sustainable biomass sourcing,
below).

Process-specific considerations
Biochar project developers•

Must verify that biochar is not used for combustion applications or otherapplications that would lead to rapid release of CO2 to the atmosphere.

•

Must provide biochar elemental analysis (C, H, O) to substantiate storage
durability and account for biochar recalcitrance and carbon loss over a 100-yeartime frame based on best available models.

•Must provide a cradle-to-grave LCA to quantify net-negativity of biochar(e.g., European Biochar Certificate C-Sink with CarbonFuture, Puro) and makeappropriate deductions to calculate net CDR.

•

Must ensure that biochar is tested to minimize environmental harms (e.g.,adhere to guidelines from the International Biochar Initiative or European Biochar
Certificate).

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•Must prove that the production of biochar results from affirmative practices,or the deliberate modification of an existing facility to produce biochar, for the
purposes of additionality.

•

Should measure biochar decay rates after application and share this data
to improve decay models, including decay rates for recalcitrant and labile
fractions.

Wood harvesting and storage developers•

Must bury only coarse woody material until sufficient scientific consensus isreached on decay rates of fine woody biomass in abiotic conditions.

•Must bury wood in a burial chamber surrounded by a layer of low permeability
material.

•

Must provide a cradle-to-grave LCA that includes all relevant portions of the
supply chain, including disturbed topsoil and transport of biomass feedstock.

•

Must use in-situ sensors, gas sampling of CH4, sample excavations, and/or site
maintenance for MRV.

•

Should create conditions that achieve an anoxic environment, inhibiting
biological degradation.

•

Should minimize the risk of disturbance by biotic agents like termites and deeprooted plants.

Developers who rely on geologic storage of CO2 (e.g., BECCS) must follow
guidance set forth for durability of direct air capture (DAC) in this document.

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Other considerations
Biomass sustainability
PROJECT DEVELOPERS MUST•

Avoid sourcing biomass from primary forests and areas with high conservation value.

•

Utilize biomass from sources with operational integrity and oversight through strong
governance, management standards, and supply chain transparency (e.g., throughcertified forest management).

•

Source forest biomass only from regions with stable or increasing forest carbon stocks,
unless carbon accounting transparently and conservatively incorporates decreases inthose stocks.

•

Source biomass that does not distort markets for agriculture or forestry products (e.g.,
avoid biomass from roundwood that would otherwise be used for long-lived wood
products).

PROJECT DEVELOPERS SHOULD•

Propose projects that have a minimum Technology Readiness Level (TRL) of 7,
corresponding to a “system prototype demonstrated in a plant environment,” as defined by
the National Academies, 2019. Specifically, technology should have:•

Demonstration of an actual system prototype in a relevant environment.

•

Final design virtually complete.

•

Demonstration-scale prototype, defined as 5–25 percent of final scale or design, or a50-250 t/d dry biomass plant.

•

Undergone large pilot-scale testing using dry biomass feedstock at a scale equivalent toapproximately 50-250 t/d (excluding projects that have demonstrated full-scale mobile/
modular processing units).

•

Describe key business model risks, including the structure and stability of subsidies, andtechnical risks, including a reasonable plan to mitigate those risks.

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ENGINEERED

Direct Air
CaptureDirect air capture (DAC) projects involve mechanical and chemical systems that remove
and concentrate CO2 from ambient air. This CO2 is then used as a feedstock or returned
to a long-term carbon sink. DAC projects typically do not require rare or critical materials
and could be sited in many geographies (including near CO2 storage resources and lowcost or stranded low-carbon energy assets).
Net-negative DAC projects rely on large amounts of low-carbon energy, both heat andelectricity, which may limit deployment speed and scale. The following principles for DAC
build upon those detailed previously under Essential principles for high-quality carbon
dioxide removal.

0 Harms and benefits
These criteria build on and extend the harms and benefits considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Assess potential impacts from sorbent or solvent slip downwind of the facility, even
if compliant with general health and safety guidelines and all applicable local/regional
regulations.

•

Articulate a strategy to measure and mitigate any material impacts to air, water, and land
quality, including emissions due to solvent or sorbent slip and discharge into local air,water, and land.

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PROJECT DEVELOPERS SHOULD•

Minimize need for new inputs (e.g., energy, construction materials, sorbents/solvents) byapplying best practices in reuse and circularity.

•

Monitor and improve material and process efficiency.

Environmental justice
These criteria build on and extend the environmental justice considerations included under
Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Avoid development or disturbance of land that has been identified as culturally sensitiveor ecologically important by community stakeholders. This includes land used directly for
DAC facilities, land used for renewable energy installations to power DAC facilities, andland used for CO2 transport or geological storage.

•

Prevent community displacement by ensuring that any new or expanded pipelines, roads,
wells, or other infrastructure do not inequitably impact historically disadvantaged or
marginalized communities.

•

Evaluate and mitigate any adverse impacts from increased water consumption. These may
include increased water prices and/or decreased local water quality, including discharges
from capture facilities and sorbent/solvent manufacturing facilities.

PROJECT DEVELOPERS SHOULD•

Pay a living wage and actively promote long-term economic opportunities for local
communities by providing training programs that develop a pipeline of skilled local workers
skilled at DAC management and operation.

•

Detail any associated land-use changes, including any new infrastructure required for
project deployment, which could have negative community consequences.

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Additionality and baselines
These criteria build on and extend the additionality and baselines considerations
included under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Explain the economic viability of the project with or without the requested investment and/ or
CDR procurement, and the role of tax or policy incentives (for example in the United States
45Q, or in some EU countries state auctions for carbon removals).

•

Quantify baseline GHG fluxes and expected GHG fluxes from energy consumption, site
preparation, carbon storage/utilization, decommissioning and end-of-life.

Carbon accounting and MRV
These criteria build on and extend the carbon accounting and MRV considerations included
under Essential principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Account for all sources of emissions through the entire project lifecycle, such as direct andindirect land-use change, concrete and steel production and construction, procurementof capture media and chemicals, disposal of waste products, and energy use during DAC
operations.

•

For a project using fossil-fuel energy sources, include full lifecycle impacts encompassing
both upstream leakage and downstream usage in their carbon accounting considerations(regardless of whether co-capture is involved in the process).

•

Include full lifecycle impacts of the electricity powering operations, including grid-related
emissions from grid-connected power purchase and use.

•

Present a valid and viable MRV plan that adheres to key regulatory requirements (forexample, Class VI well permits) for either subsurface storage or carbon utilization
products.

•

Demonstrate displacement of high carbon-intensity products or processes for DAC
projects coupled to CO2 utilization.

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PROJECT DEVELOPERS MUST•

Design a project that emits less than 0.3 tonnes of CO2e per tonne CO2 removed.

•

Use energy with low associated emissions.

•If applicable, clearly demonstrate new, low-carbon electricity generation was added to thegrid (or grid balancing-area) that serves the project. If the project proposes to purchaseelectricity from the grid, it should provide a copy of its power purchase agreement
including the electricity emissions factor and provide the latest emissions factor for the
local Transmission System Operator.

•

Ensure measurements include emissions throughout the entire value chain of a project(from upstream to operational emissions) across all types of greenhouse gases, including
fugitive emissions from compression, transport, and storage of CO2.

Durability
These criteria build on and extend the durability considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST DEMONSTRATE•

Sufficient CO2 storage capacity for the entire project lifetime identified and developed
as part of the project; or sufficient physical CO2 offtake identified and contracted withcredible third-party providers.

•Sufficient injectivity at storage site, including well count.

•

Low CO2 release risk as estimated by the methodologies outlined in the WRI’s guidelines
for CO2 capture, transport and Storage, Section 4.3.1.2•

An MRV plan, consistent with best practices for the chosen storage location, to detect
unplanned physical leakage or reversals.

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Leakage
These criteria build on and extend the leakage considerations included under Essential
principles for high-quality carbon dioxide removal.
PROJECT DEVELOPERS MUST•

Demonstrate that any new energy needed for DAC operation does not extend or create
new demand for emissions-intensive energy.

Other considerations
Materials
PROJECT DEVELOPERS MUST•

Demonstrate that process inputs, including capture media, have low operational safety risk.

PROJECT DEVELOPERS SHOULD•

Use earth-abundant inputs, such as magnesium, calcium, silicates, sodium hydroxide, orother such inputs appropriate for a given process.

•For solvent-based systems, produce, transport, store, and manage solvent and solvent
degradation products with low risk to operators, neighboring communities, and theenvironment.

•

For sorbent-based systems, demonstrate the ability to synthesize sorbent at 1 metricton per year scale or at a scale consistent with the project timeline, and present a viablestrategy for sorbent recycling or disposal.

Infrastructure
PROJECT DEVELOPERS SHOULD•

Describe relevant transmission infrastructure, including new power and utility lines andCO2 pipelines.

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Scalability
PROJECT DEVELOPERS MUST•

Present reasonable cost estimates, ideally verified by third parties, peer review, or
demonstrated in prior projects.

•

Test and validate that thermal and electrical energy supply matches theoretical
thermodynamic energy requirements.

•

Demonstrate the capacity to manufacture or procure proposed design components andsystems.

•

Ensure viable low-carbon energy supply at scale, ideally via evidence of contracted or captiveenergy supply.

PROJECT DEVELOPERS MUST•For first of a kind DAC technology, successfully construct and operate prototypes that build
confidence in DAC feasibility and efficacy at scale.

•

Ensure vendors and subcontractors provide performance, schedule, and cost data for key
DAC technologies.

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Conclusion
Thank you for engaging with Microsoft and Carbon Direct on high-quality carbon dioxide
removal (CDR). Our collaboration builds upon the previous years’ work, incorporating thelatest research findings and industry insights. This iteration of the guidance reflects theseadvancements, while also setting the stage for future improvements. We are committed toregularly updating and refining these recommendations to ensure that we can provide themost relevant and actionable information for a rapidly evolving industry.

We recognize that this work is part of a collective effort, and we encourage open dialogue
within the CDR community. We welcome feedback, comments, and questions about theguidance presented in this document. Please feel free to reach out to Microsoft’s Carbon
Removal team at mscdr@microsoft.com and Carbon Direct at info@carbon-direct.com.
Engaging in active discourse is vital to driving innovation and refining our understanding of
high-quality CDR.
To foster the growth of the CDR market and facilitate the development of high-quality
projects, we call upon the support of financial institutions, project developers, and thewider CDR community. It is through increased investment, collaboration, and community
engagement that we can collectively build a strong foundation for the future of carbon
removal. We invite interested parties to explore Microsoft’s procurement cycle andconsider how they can contribute to the pipeline of high-quality CDR projects. For more
information on the Microsoft procurement process or to inquire about potential partnership
opportunities, please visit the Microsoft Carbon Removal Program page.
Ultimately, our goal is to contribute to a rapid and just climate transition. By collaborating,sharing insights, and promoting transparency, we can create a robust CDR market that willplay an essential role in combating climate change. Thank you for your engagement — welook forward to working with you as we continue on this vital journey.

The information in this document represents the current view of Microsoft and Carbon Direct on the content.
It is for informational purposes only. MICROSOFT AND CARBON DIRECT MAKE NO WARRANTIES, EXPRESS,IMPLIED, OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.

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