Key to understanding the discussion around Natural Climate Solutions is understanding the terms commonly-used in scientific studies, policy briefs and other literature. This glossary is compiled from a variety of sources, including government agencies and non-profit organizations, to provide plain-English definitions of these terms. Links to the original sources are provided after each definition. In some cases, terms were edited for clarity.

Carbon Offsets or Carbon Credits

Carbon Offsets or Carbon Credits are the act of compensating or canceling out all, or a portion of, the GHG emissions released to the atmosphere through investments in activities that reduce or remove an equivalent amount of GHG emissions and which are located outside the boundaries of the organization or a particular product system. Such investments are often in the form of purchasing a carbon credit. (VCMI)

Carbon Offset Protocols

Carbon Offset Protocols, also referred to as carbon credit protocols or methodologies, generally set forth a method for quantifying emissions reduction from a proposed carbon project, as well as requirements to demonstrate additionality, permanence, and quantify uncertainty and leakage, and are developed to ensure that the proposed project produces the emissions reductions for which it is being paid by a capped source. (Columbia Law School/USN4C)

Greenhouse Gas Inventory

Greenhouse Gas Inventory is a process that accounts for all human-caused emissions and removals of greenhouse gases (GHG) associated with a specific entity (e.g., a country, a company). The inventory essentially acts as a climate change balance sheet, tracking the total volume of GHG emitted from sources like fossil fuel consumption and agricultural production alongside the volume of GHG removed by sequestration in plants and soils or through technological means. (WRI/USCA)

Carbon Crediting Program

Carbon Crediting Program, also referred to as a carbon standard, an entity that develops and promulgates standards (i.e., requirements, methodologies, and protocols) that must be adhered to by project developers and third-party validators in order for a project to issue a carbon credit. The carbon crediting program lists projects on a publicly available registry system and issues carbon credits for the emission reductions or removals achieved by the activities. (VCMI,WWF)

Carbon Bank

Carbon Bank is a proposal that would enable the U.S. Department of Agriculture’s Commodity Credit Corporation to buy, insure, and/or provide price guarantees for carbon credits from farmers, ranchers, and forest owners. This would help reduce obstacles to participation in voluntary carbon markets by de-risking carbon investments by landowners. (BPC)


Baseline — the baseline for any carbon management project is often described as the “business-as-usual” case or the amount of GHGs that would be emitted or sequestered if the project was not enacted. (TNC)


Additionality represents the fact that the project and its emission reduction would not have happened without the intervention of the carbon market, based on an analysis of barriers to implementation of the project activity.  (TNC)


Leakage refers to a situation where an activity within the project boundary triggers an emission on lands outside of the project boundary. Two common forms are activity-shifting leakage and market leakage. Activity-shifting leakage occurs when activities inside the project boundary (e.g. land conversion) relocate outside of the boundary. Market leakage occurs when project activities affect an established market for goods (e.g. farmed products) and causes the substitution or replacement of those goods elsewhere. (TNC)


Permanence refers to the longevity of a carbon pool. Under most carbon standards, an increased carbon stock or avoided loss of carbon stock as a result of a project activity must be maintained for a long period (usually at least for 100 years), and its reversal must be avoided. Permanence is important when emission reductions or removals are used as offsets – if the underlying carbon stock disappears, this is considered a “reversal”. Most carbon methodologies require a buffer pool to ensure against some projects having a reversal, such as could occur due to wildfire or illegal logging. (TNC)


 Verification is the confirmation of a claim, through the provision of objective evidence, that specified requirements have been fulfilled. (ISO) In the context of greenhouse gas inventories, verification is the process used to ensure that an organization’s greenhouse gas emissions inventory has met a minimum quality standard and complied with a carbon registry’s and protocols for calculating and reporting GHG emissions. (The Climate Registry)