ESG as Modifying Factors in Ore Reserve Declarations

Mineral Resource and Ore Reserve estimates have always required technical justification. Today they also require social and environmental justification. Regulators, investors, and communities now expect that a project’s social license, climate exposure, and ESG commitments appear in the same technical documents as grade, tonnage, and cost. For the signing professional, this is not a documentation problem. It is a modifying factor problem.

What the Reporting Codes Actually Say About Modifying Factors

The JORC Code, NI 43-101, and S-K 1300 all follow the same logical structure. A Mineral Resource becomes an Ore Reserve only after modifying factors are applied. The codes list those factors explicitly: mining, metallurgical, economic, marketing, legal, environmental, infrastructure, and social or governmental factors. Environmental and social factors are not secondary items to be addressed in an appendix. They appear alongside metallurgy and mine design as conditions that must be satisfied before the conversion is valid.

Under the JORC Code, the Competent Person must have reasonable grounds to believe that extraction could be justified. Under NI 43-101 and S-K 1300, the Qualified Person carries the same obligation. In both cases, the signing professional must show that the project can proceed, not simply that the ore is present. If a community has blocked access to a proposed pit, or if a climate-related water risk has not been addressed in the mine design, the Ore Reserve declaration cannot be supported regardless of how strong the grade and tonnage appear.

This is not a recent change in the codes themselves. It is a change in what regulators, exchanges, and institutional investors now expect to see documented. The risk for technical teams is that the social and environmental work was completed by another department, was never translated into the reserve model, and was therefore not visible to the Competent Person or Qualified Person when they signed the statement.

How ESG and Climate Costs Enter the Reserve Model

Social license and climate risk affect the Ore Reserve through two distinct paths. The first is cost. The second is schedule, access, and feasibility.

On the cost side, carbon pricing is the most direct mechanism. Where a jurisdiction applies a carbon tax, or where a company has made a net-zero commitment that includes an internal carbon price, that cost belongs in the operating cost used to calculate the cut-off grade. A higher operating cost raises the cut-off grade, and a higher cut-off grade produces a smaller Ore Reserve from the same block model. The reserve becomes smaller not because the geology changed, but because the project economics changed. A Competent Person or Qualified Person who signs without incorporating these costs is working with an incomplete cost model.

Water presents a similar situation in many Andean, Mexican, and Chilean operations. Water rights in arid regions are increasingly constrained. If a project requires water supply infrastructure that has not yet been permitted, that infrastructure cost belongs in the capital cost. If water availability limits processing throughput, that limit belongs in the LOM schedule. Leaving water risk out of the model understates the capital requirement and overstates the production profile.

Community agreements also carry real cost. Benefit-sharing arrangements, local employment commitments, and infrastructure contributions to nearby communities are genuine project costs. They are often negotiated before a project reaches the reserve declaration stage, and they are sometimes excluded from the financial model because they were handled by the social relations team rather than the technical team. If those costs are material relative to the project margin, they affect the cut-off grade and the reserve boundary. The cut-off grade analysis must reflect the full cost structure the operation will actually face.

On the access and feasibility side, the integration is less mechanical but equally important. A pit that crosses into an area where access is contested is not a mineable pit. An underground decline that requires consent from an indigenous community that has not provided that consent is not an approved development. The Ore Reserve can only include material for which extraction is reasonably justified. If that justification depends on permits or agreements that do not yet exist, the Inferred and even Indicated portions of the model that rely on that access should not appear in the reserve statement until the conditions are met.

The Strategy and Reserves work at Agmines treats these factors as part of the reserve logic, not as risk disclosures added after the technical work is complete.

Making the Documentation Defensible

The practical challenge is not identifying these risks. Most technical teams already know where the social and environmental exposures are. The challenge is documenting them in a way that the signing professional can fully support, and that a reviewer, regulator, or investor can audit.

Three things make that documentation defensible.

First, the modifying factors must be explicitly addressed in the technical report. Under the JORC Code, Table 1 requires responses on environmental studies, waste characterization, water, infrastructure, land tenure, and community consultation. Those responses must describe the actual status of each item, not general policy language. Under NI 43-101 and S-K 1300, equivalent sections in the technical report require the same level of specificity. A statement that the company has an ESG policy is not a modifying factor assessment. A statement that water extraction permits for the LOM volume have been granted, that community benefit agreements are in place and costed, and that carbon costs are included in the operating cost model: that is a modifying factor assessment.

Second, the financial model used for the Ore Reserve must include all material costs. This means the business plan analysis and the reserve model need to share the same cost assumptions. When the social relations team negotiates a community commitment and the technical team calculates the cut-off grade without knowing the cost of that commitment, the two models are inconsistent. The signing professional is then certifying a reserve based on a cost model that does not reflect the project’s actual obligations.

Third, climate-related risks that affect the LOM schedule must be stress-tested. Physical climate risks such as reduced water availability, more frequent extreme weather events, or temperature effects on tailings behavior are increasingly material in long-life operations. Transition risks such as carbon pricing changes over the LOM period, shifts in energy cost assumptions, or stricter closure requirements are also relevant. The mine technical risk assessment is the appropriate place to record how these scenarios were evaluated and what the effect on the reserve would be under different assumptions. This is not a separate ESG report. It is part of the technical justification for the reserve.

The connection between the reserve model and the operating plan also matters here. An Ore Reserve that incorporates environmental and social costs should produce a mine plan that reflects those costs in the scheduling and sequencing logic. If the LOM plan sequences material from an area where community access is conditional on an annual review, that condition needs to appear in the schedule assumptions. The mine planning and design process must carry the same modifying factor logic that the reserve model uses.

Why This Matters Now

Regulatory expectations have increased. The SEC’s S-K 1300 rules, which replaced Industry Guide 7, require more detailed disclosure of the assumptions behind a reserve, including social and environmental assumptions. Stock exchanges in Canada, Australia, and the United Kingdom are applying climate disclosure requirements that connect directly to reserve-supporting assets. Institutional investors with ESG mandates are asking technical questions that previously came only from regulators.

At the same time, operations in Peru, Mexico, Chile, and other parts of Latin America have demonstrated that social license failures are a direct cause of project suspension. These are not reputational events. They are operational events that stop ore movement, close pits, and destroy the reserve value that the technical team spent years building. When social license is treated as a modifying factor from the start of the reserve process rather than added as a disclosure at the end, the technical documentation reflects the real conditions of the project, and the signing professional’s position is much stronger.

The Competent Person or Qualified Person who treats ESG, climate, and social license as core modifying factors is not doing additional work beyond the standard. They are doing the reserve work correctly.

If your operation is preparing a reserve update or reviewing your technical reporting obligations under JORC Code, NI 43-101, or S-K 1300, and you want to confirm that environmental, social, and climate factors are properly incorporated into the modifying factors analysis, contact the Agmines team. We work in English and Spanish and we have direct experience with reserve reporting across open pit and underground operations in the Americas. Reach us at agmines.com/contact.