Article 6, ITMOs, and Carbon Removal: A Plain-English Guide to a System That’s Finally Becoming Real

For years, Article 6 lived in a strange limbo.

Everyone knew it mattered.
Very few could point to anything concrete actually happening.

That has changed.

If you’re hearing Article 6 mentioned more often lately, it’s not because the language suddenly got clearer. It’s because, around 2024 and 2025, the system quietly moved from rule-making to early implementation.

That shift matters, especially if you work with carbon dioxide removal, or CDR.

So instead of treating Article 6 as a future mechanism, this is an attempt to explain what it is, how it works, and where it actually stands today.

What Article 6 is designed to do

Every country under the Paris Agreement has a climate target. These targets, known as Nationally Determined Contributions or NDCs, define how much a country intends to reduce or remove emissions.

In theory, each country could meet its NDC entirely within its own borders.

In practice, that has never been realistic.

Some countries have access to cheap renewable energy.
Some have geology suitable for CO₂ storage.
Some have biomass, land, or industrial systems that make removals easier to scale.

Article 6 exists because the Paris Agreement accepts this uneven reality. It creates rules that allow countries to cooperate on climate action while preserving the credibility of national targets.

For a long time, those rules were incomplete. Most of the energy between COP26 and COP29 went into negotiating text, definitions, and edge cases.

By the end of 2024, that phase largely closed.

From rulebook to early use

By COP29, the core Article 6.2 and 6.4 texts had been agreed, and the focus shifted into implementation while technical negotiations pause until 2028.

In 2025, the conversation changed again.

Instead of asking “What should the rules be?”, countries began asking “How do we actually use this?”

That change is subtle but important.

In 2025:

• Several countries issued Letters of Authorization for projects and submitted them to the UNFCCC
• Only a small number of countries had publicly completed the full accounting cycle by reporting applied corresponding adjustments
• The UN body overseeing Article 6.4 adopted key standards, and the first PACM methodology was approved just before COP30

These are not large volumes yet. But they are real signals that Article 6 is moving from concept to infrastructure.

Cooperation, but with guardrails

Article 6 is not one mechanism. It’s a framework with multiple pathways.

The two most relevant are Article 6.2 and Article 6.4.

Article 6.2 governs direct cooperation between countries. In practice, this looks like bilateral agreements where one country funds or purchases climate outcomes generated in another country.

By 2025, dozens of these agreements had been signed. A smaller number progressed to actual transfers, but enough to demonstrate that the system can function.

Article 6.4 creates a centralized UN mechanism that issues carbon credits under common rules, replacing the old Clean Development Mechanism. In late 2025, the first methodology under this new mechanism was approved, allowing projects to begin registering under Article 6.4 in earnest.

Both pathways are built around the same concern.

If a climate outcome is used by one country, it should not be counted by another.

ITMOs, in practical terms

ITMO stands for Internationally Transferred Mitigation Outcome.

The term sounds abstract because it describes an accounting status, not a technology.

An ITMO is simply a quantified climate outcome that a host country has authorized for transfer to another country. It can represent one tonne of CO₂ reduced or removed.

What makes it an ITMO is not how the tonne was generated, but how it is treated in national accounting.

When a country authorizes a transfer, it is effectively saying:
“This outcome will not be used toward my own NDC.”

In 2025, only a handful of countries had completed this full process end to end. That scarcity is part of why ITMOs are discussed more than they are seen.

Corresponding adjustments, and why timing matters

Corresponding adjustments exist to prevent double counting. The logic is simple, but the implementation is slow.

When a host country exports a climate outcome as an ITMO, it commits to adjusting its national emissions balance. The adjustment is reported through formal transparency reports submitted to the UN.

In practice, this means there can be a time lag between a transfer happening and the corresponding adjustment being publicly visible.

As of 2025, only a few countries had publicly reported applied corresponding adjustments. That does not mean others are non-compliant. It reflects how new and administratively heavy the system still is.

This is why corresponding adjustments are better understood as sovereign accounting commitments, not instant project-level switches.

Article 6.2 and 6.4, where we are now

Article 6.2 is currently the more active pathway.

Countries like Switzerland, Japan, Singapore, and others have moved fastest, signing agreements and piloting early transfers. Much of the near-term demand is also linked to international aviation under CORSIA, which begins its compliance phase later this decade.

Article 6.4 is slightly behind, but catching up.

In 2025, the supervisory body overseeing the mechanism finalized key standards, including permanence for removals. The first methodology was approved, allowing projects to start transitioning from the old CDM or registering anew.

The distinction between authorized credits and mitigation contributions is now clearer, even if the market is still learning how to use each category.

Where carbon removal enters the picture

Carbon dioxide removal is often discussed in the context of Article 6 because removals fit relatively cleanly into accounting frameworks.

A tonne removed is a physical outcome. It does not depend on avoided emissions scenarios. That simplicity matters when outcomes are being transferred between national inventories.

At the same time, removals face the same institutional constraints as any other activity.

In 2025, the limiting factor for Article 6-aligned CDR is rarely technology. It is more often:

• whether host countries are willing to authorize removals for export
• whether registries and reporting systems are in place
• whether governments want to reserve removals for their own long-term targets

These are policy decisions, not technical ones.

Why this matters now

Article 6 is still early. Volumes are small. Processes are slow.

But the shift from abstract rules to real, if limited, use has already happened.

For people working with carbon removal, this means Article 6 is no longer just a future alignment question. It is a framework that is beginning to shape how claims, ownership, and national priorities interact.

Understanding it does not require choosing sides or predicting outcomes.

It simply requires recognizing that the system is now live, imperfect, and evolving.

And that makes it worth understanding in the present tense, not just the future one.