Understanding Carbon Offsets

Methodologies & Standards

The distinction between methodologies, programs, standards, and registries can be confusing since the terms are loosely defined. For example, several crediting programs call themselves “standards” like the Verified Carbon Standard or Gold Standard and “registries” like the American Carbon Registry though these are independent crediting programs that have the same basic functions and components. We suggest you use these general definitions:

Project Methodologies

Project methodologies cover GHG accounting rules and program requirements for monitoring, reporting, verification, and certification. In other words, they outline the rules and procedures to determine project eligibility, additionality, and baseline and project emissions for a particular project type. The terms “methodology” and “protocol” are often used interchangeably. Crediting Programs either have their own methodologies for a set of project types or approve the use of methodologies developed by another crediting program.

Crediting Programs

There are three core components of a carbon crediting program:

  1. Eligibility definitions and rules for the design and early implementation phase of a project. They can include additionality and baseline methodologies, definitions of accepted project types, and procedures for validating project activities.
  2. Monitoring, reporting, verification, and certification rules ensure that crediting projects perform as they were predicted to during project design. Certification rules are used to confirm the actual avoided GHG emissions or enhanced removals that can enter the market, as carbon credits, once the project is implemented.
  3. Registration and enforcement systems clarify ownership, enable trading of credits, track credit retirement, and ensure that credits are not double counted through sale to multiple buyers. These systems must include a registry with publicly available information to uniquely identify crediting projects and a system to transparently track ownership and ownership transfers of credits.


A carbon credit registry is a system for reporting and tracking crediting project information including project status, project documents, credits generated, ownership, sale, and retirement. Crediting Programs must utilize a registry.


Standards can include methodologies and guidance documents. These standards provide guidance and/or specifications on GHG quantification, monitoring, reporting. Stand-alone standards typically do not have an associated regulatory body that registers projects and also do not typically have registration and enforcement systems to track and ensure legal ownership of carbon credits (e.g., ISO 14064-2). In other words, standards do not have registration and enforcement systems. The use of a standard alone is therefore not sufficient to guarantee the quality of carbon credits. Many crediting programs have their own standards, as part of their program, that outline requirements and guidance for crediting projects using their system.