We are pleased to announce the launch of the public consultation for the update to the Puro Enhanced Rock Weathering (ERW) methodology.
This update reflects the rapidly evolving science and technology behind ERW, ensuring that our methodology remains both scientifically rigorous and practical for carbon removal suppliers and project developers worldwide. It also aligns the ERW methodology with the latest Puro General Rules and the ICVCM CCP.
For this update, we have collaborated with a diverse group of experts from academia, industry, and the non-profit sector, held three workshops, and interviewed other relevant stakeholders. We thank all of them for their invaluable contribution to the methodology development process.
Major Changes Introduced in this Update
- Enhanced quantification approaches: A detailed description of eligible CDR measurement approaches has been added to ensure reliable quantification of carbon removed. Six different approaches are prescribed in this update. To ensure robustness, the methodology requires the combination of two approaches: one to quantify stored CO2, and one to validate this quantification.
- Detailed sampling requirements: Clear sampling guidelines ensure scientifically sound and statistically representative measurement of CDR through careful characterization of soil chemistry with an emphasis on measurement precision and accuracy and the rigorous use of control plots for carbon accounting.
- Clarified role of modeling: Quantification of CDR always requires site-specific field measurements, and modeling is recognized as an optional tool to extrapolate data from these measurements.
- Updated accounting for loss terms: Losses are explicitly addressed with clear instructions for their quantification and accounting. They include secondary mineral formation, cation adsorption, plant loss, non-carbonic acid weathering, as well as river and ocean losses.
- Uncertainty management: The update introduces an uncertainty discount and requires robust quantification of uncertainty by frequentist or Bayesian approaches for the different components of the carbon removal calculation (“CORC equation”).
Public Consultation Period: September 8 – September 28, 2025
How to Participate
We invite all stakeholders, scientists, project developers, and interested parties to review the draft methodology and provide feedback. Your insights during the public consultation period are invaluable to ensure the robustness and applicability of this methodology in supporting high-integrity carbon removals.
To participate, download the methodology draft and the feedback form using the links below. You can submit your insights and comments using the feedback form. Remember to send it to contact@puro.earth by September 28th.
Download the Methodology Draft
Webinar
A webinar to present the methodology and answer stakeholder questions will be held on September 17th at 11:00 a.m. EST / 3:00 p.m. UTC.
Key Areas for Feedback
As part of this public consultation, we invite stakeholders to provide input on specific aspects of the draft methodology. In particular, we seek feedback on:
- Quantification approaches – Is the selection process appropriate, and are the methods described in sufficient detail?
- Sampling strategy and density – Are the requirements clear and feasible for ensuring representative measurements?
- Loss term accounting – Are the proposed approaches for capturing potential losses adequate and scientifically sound?
- Quantifying and discounting uncertainty – Are the proposed approaches robust, practical, and transparent?
- Environmental risk requirements – Are the requirements comprehensive and proportionate to potential risks?
Your feedback on these topics will help strengthen the methodology and ensure it is scientifically rigorous, practical to implement, and aligned with best practices.
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