Carbon credit methodology

The carbon market data is taken from the four main voluntary carbon market registries– Verra, Gold Standard, The American Carbon Registry and Climate Action Reserve. We update the data quarterly.

Seven project types are used in the analysis (renewable energy, energy efficiency, fuel switch, REDD+, non-CO2 gases, other NBS, other). “REDD+” means Reduced Emissions from Deforestation and Degradation. “Other NBS” refers to Other Nature Based Solutions including reforestation and agriculture and land-use projects. “Non-CO2 gases” mostly includes methane reduction projects, for example from landfill gas. Fuel switch includes cook stoves projects. These seven project types are drawn from 56 project technologies types in the registries. “REDD+” are identified using specific methodologies.

The event date is the date when a particular event occurs. These can be issuances, retirements or cancelations. A single project will have many event dates since credit issuances, retirements and cancelations can happen multiple times a year over the full crediting period of the project.

The project start date is the date when the project commenced operations as recognised by the verification body.

The vintage of a credit is the year in which the emission reduction or removal occurred, irrespective of the date the credit was issued. For example, if a project issued credits in 2020 with a 2016 vintage, the credits issued represent emission reductions in 2016.

An issued credit is added to a registry inventory once the issuance event has been verified by an accredited verification body. Once a credit is issued, it can be purchased, typically, for the purposes of voluntary offsetting or compliance.

Issued credits exclude Planned Emissions Reductions (PERs) in the Gold Standard registry. A PER represents a potential future issuance and in our analysis all credits are captured at the time of issuance.

A retired credit shows when an issued credit has been used by the buyer – mostly for offsetting against an emission elsewhere. When a credit is retired it is no longer available for use.

A cancelled credit is a credit that has been retired for compliance purposes, and relates mostly for use in the California Cap and Trade programme. Carbon credits issued to the voluntary carbon market can be used for compliance in the California scheme or for offsetting by private buyers. Cancelled credits have the same status as retired credits in the registries, that they are no longer available for purchase.

Credits issued to buffer pools are excluded from issued credit volumes. Buffer pools are used to set aside a proportion of credits from forestry projects to provide a bank of un-used credits to be used if the there is an underperformance in the project – for example due to drought, die-back or fire. As such, buffer pool credits are not available as extra supply to the market.

The voluntary carbon market surplus is calculated by subtracting the volume of cumulative retired and cancelled credits from the cumulative volume of issued credits for each project type.

Trove Intelligence is the leading source of data and analytics on corporate climate commitments and the voluntary carbon market. Trove Intelligence is part of Trove Research which provides research and consulting services to corporates, think tanks and governments on climate strategies, carbon markets and the energy transition.

The data behind the charts above have been assembled from the Trove Intelligence meta-registry of voluntary carbon market transactions, comprising the world’s top four carbon registries. For more information and feedback please contact