Greenhouse gas Abatement Cost Model (GACMO)

Calculating current and future greenhouse gas emissions is a prerequisite for countries to inform political decisions concerning climate action. It is also the foundation for transparent and credible climate action at national and global levels.

The GACMO (Greenhouse Gas Abatement Cost Model) tool is a bottom-up greenhouse gas (GHG) emissions accounting tool developed over more than twenty years by the UNEP Copenhagen Climate Centre (UNEP-CCC).

The GACMO tool allows countries to carry out rapid but accurate evaluation of how a variety of mitigation options impact GHG emissions. The tool is used to calculate the GHG emissions projections for the business-as-usual (BAU) scenario and for the mitigation scenario based on a set of selected mitigation options. These options can be, for example, the mitigation options adopted or planned by a government and specified in national climate plans or a country´s Nationally Determined Contribution (NDC). The GACMO tool can also be used to compare new mitigation options in terms of their abatement costs and mitigation potential to identify the set of mitigation options appropriate for a country. The GACMO tool can thus support technical experts and decision-makers to assess and understand the GHG emissions impacts of climate mitigation actions.

The GACMO tool can also be used to monitor the GHG emission reductions achieved through the effective implementation of mitigation options. Therefore, it can be used as a tool for tracking the progress in achieving emissions reductions from the implementation of climate change mitigation options, for example in the context of tracking the progress in implementing and achieving the NDC.

The GACMO tool can be used at the national level (country level) but can also be adapted to be used at the sub-national level (region or city). It can be very useful for the preparation of national reports such as national communications, biennial update reports (BURs), biennial transparency reports (BTRs) including the common tabular format tables (CTF), or for the preparation and update of NDCs.

All the versions of the GACMO tool can be downloaded and used free of charge by any user and can be installed on a personal computer.

The tool is regularly updated. The last version of the GACMO tool is always made available on this webpage.

The new version of the GACMO tool (version 2.01) has been developed with the support of the Initiative for Climate Action Transparency (ICAT). This new version follows the same methodological approach as the previous GACMO versions but proposes a step-by-step approach and includes an improved interface. The new version of the GACMO tool is supported by a detailed guidance and two introductory tutorials.