What are Permanence, Leakage, and Additionality in Carbon Offsets?

TL;DR

Permanence, leakage, and additionality are three core concepts that determine whether carbon offset projects deliver real and lasting climate impact. Permanence assesses how long carbon stays out of the atmosphere, leakage looks at whether emissions are simply shifted elsewhere, and additionality ensures the project wouldn’t exist without carbon finance. Sustainability managers who understand and apply these terms can make better procurement decisions, improve reporting credibility, avoid greenwashing risks, and ensure offsets genuinely support climate goals.

Why sustainability managers should understand these key terms

If you’re a sustainability manager involved in carbon offset procurement or reporting, it’s important to understand three foundational terms: permanence, leakage, and additionality. These concepts determine whether an offset project delivers real, measurable, and lasting climate impact.

This guide explains what each term means, why it matters, and what to consider when evaluating carbon credit projects.

What is Permanence in Carbon Offsetting?

Definition:

Permanence refers to how long carbon removed or avoided from the atmosphere stays out. It’s a measure of the durability of an offset’s climate benefit.

Why It Matters:

Different projects have different permanence, this is often explained in the description of the specific climate projects. This enables you to make a decision that is in accordance with your company’s climate strategy.

What to consider:

• Potential risks ofreversal

• Projects with high permanence are often highly technical, (e.g. Direct Air Capture), making them more costly

Key question to ask:

“What happens if this carbon is released again, and how is that risk managed?”

What is leakage in carbon offset projects?

Definition:

Leakage happens when emissions avoided in one place lead to increased emissions elsewhere.

Example:

If a forest conservation project pushes logging to a nearby region, the global net emissions may not change.

Why It Matters:

Leakage reduces the actual climate benefit of a project, making it less credible.

What to consider:

• Engagement with local communities

• Independent monitoring and disclosure of leakage risks

Key question to ask:

“Does this project cause emissions to shift to another area or sector?”

What is additionality in carbon offsetting?

Definition:

Additionality means the emissions reduction or removal would not have happened without carbon finance. It ensures that the project is enabled by the purchase of carbon credits.

Why It Matters:

If a project was going to happen anyway (due to profitability or regulations), buying its credits doesn’t create additional climate benefit.

What to consider:

• Evidence that the project needs carbon credit revenue to operate

• Third-party validation of additionality claims

Key question to ask:

“Would this project exist if carbon credits were not purchased?”

How sustainability managers can apply these concepts

To ensure your climate investments deliver real results:

1. Set internal evaluation criteria

Define minimum standards for permanence, leakage, and additionality before purchasing offsets.

2. Use trusted registries

Choose projects listed under certification standards like Verra, puro.earth and Gold Standard that evaluate these factors when giving out certifications , or those vetted by players like Atmoz.

Learn more about certifications here

3. Align your climate claims

If a project offers 30-year storage, don’t communicate it as “permanent” in your reporting. Make sure your claims are a reflection of reality, don’t overexaggerate.

4. Document your process

Transparency in evaluation builds trust with regulators, auditors, and stakeholders.

Why these terms matter in Sustainability Reporting

Frameworks like Beyond Value chain mitigation (BVCM) from the Science Based Target Initiative ( SBTi) increasingly expect companies to disclose not just that offsets were used, but how the projects were evaluated.

Understanding permanence, leakage, and additionality helps:

• Build stronger procurement policies

• Improve reporting accuracy

• Avoid greenwashing accusations

• Support real climate impact

Choose high-integrity offsets with Atmoz

Atmoz helps sustainability teams navigate the carbon offset landscape by offering access to pre-vetted projects that meet high standards for permanence, leakage, and additionality. We make it easy to find and invest in climate projects that support your goals - with full transparency and expert guidance. Please reach out to our offset and climate experts to get an introduction or view selected projects in our portfolio here.

Why should sustainability managers understand permanence, leakage, and additionality?

These terms define the integrity of carbon offsets. Understanding them helps ensure that purchased credits deliver real, measurable, and lasting climate benefits-and stand up to scrutiny from auditors, regulators, and stakeholders.

How can sustainability managers apply these concepts in practice?

Set clear internal criteria for offsets, use trusted certification standards (such as Verra, puro.earth, and Gold Standard), align climate claims with actual project characteristics, and document evaluation processes for transparency.

How does Atmoz support high-integrity offsetting?

Atmoz provides access to pre-vetted carbon offset projects that meet strong standards for permanence, leakage, and additionality, helping sustainability teams invest with confidence and transparency.