This is the glossary of important terms in carbon accounting, GHG emission, and carbon footprint management.

GHG – Greenhouse Gases

There are six major types of human-caused greenhouse gases:

  • Carbon Dioxide
  • Nitrous Oxide
  • Methane
  • Water Vapor
  • Fluorinated gases like perfluorocarbon

GHG Project

A GHG project is an activity or set of activities intended to reduce GHG emissions, store carbon and other greenhouse gases or remove them from the atmosphere.

Examples of GHG projects are: Reforestation projects or investments in clean energy

Project Activity

A project activity is part of a GHG project that aims at reducing, removing, storing, or otherwise changing carbon and other greenhouse gas emissions. Such activities are the specific measures taken in the project and may affect processes, services, or production facilities.

GHG Source

A greenhouse gas (GHG) source emits or releases greenhouse gases into the atmosphere either naturally or artificially.

There are five categories of human-made GHG sources defined by the GHG Project Protocol:

  • Combustion from grid electricity generation
  • Combustion from off-grid energy
  • Industrial Process Emissions (production of clinker for cement)
  • Fugitive Emissions (leaks from joints or pipelines)
  • Waste Emissions (e.g. landfills)

In addition, there are also natural GHG emitters such as volcanic eruptions or animals.

GHG Sinks

A GHG sink removes greenhouse gas emissions from the atmosphere or stores them temporarily or permanently.

As of today, there is only one GHG sink category:

  • Increased storage or removal of GHG by biological processes

GHG Effects

The GHG Protocol defines GHG effects as changes in GHG emissions, removals, or storage caused by project activities.

There are two types:

  • Primary Effects (intended changes relative to baseline emissions)
  • Secondary Effects (small but unintended changes)

GHG Assessment Boundary

The GHG Assessment Boundary in project accounting includes all primary and secondary effects of a GHG project and its activities. It is different from the “project boundary” which refers to physical, legal, or time-related aspects.

GHG Reductions

A reduction in the emission of greenhouse gases or an increased removal or storage thereof from the atmosphere. GHG reductions are measured relative to pre-determined baseline emissions.

Baseline Candidates