What is a municipal greenhouse gas inventory?

The Kyoto Protocol was probably the first major attempt at greenhouse gas (GHG) accounting for countries, but now cities are getting on the bandwagon as well. Greenhouse gas inventories are important for establishing a city’s climate impact and tracking changes in emissions, usually with the purpose of mitigating climate change. They can also highlight areas where local governments can target to reduce GHG emissions. So, how do local communities inventory their GHG emissions?

It’s important to be able to compare inventories from different places, so a streamlined protocol is important. The Local Governments Operations Protocol (LGOP) is one such protocol. Under the LGOP, local governments should measure the six Kyoto Protocol GHGs in units of CO2 equivalents (CO2e), which takes into account the different warming capabilities of different GHGs: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). The LGOP has three categories of emissions for each reporting entity:

  • Scope 1: all direct fossil GHG emissions
    • e.g. stationary combustion to produce energy for stationary equipment, mobile combustion of transportation fleet, process emissions from physical/chemical process other than fuel combustion, and fugitive emissions (uncontrolled, intentional or unintentional releases, e.g. refrigerator leaks of HFCs))
      • only includes fossil GHG emissions, not biogenic emissions because biomass releases carbon that was already in the carbon cycle rather than introducing carbon that has been separate from the carbon cycle for many years.
  • Scope 2: indirect GHG emissions from electricity, steam, heating, or cooling
    • e.g. power plant emissions
  • optional Scope 3: all other indirect emissions, e.g. from transportation outside the control of the reporting entity, outsourced activities, extraction and production of materials and fuels
    • e.g. employee commuting

These inventories must be considered individually for each reporting entity, so that although emissions within Scopes 1 and 2 (not 3) can be added, emissions between entities cannot in order to avoid double counting emissions. Scope 3 emissions cannot be aggregated because multiple entities can report the same Scope 3 emissions. (For more information, see Caine's post about the different Scopes.)

Once a baseline is set at the earliest year with reliable and complete data, regular inventories can reveal where emissions are coming from and which areas can be targeted to reduce GHGs. Any local government or community with a Climate Action Plan (CAP) should inventory their GHG emissions to ensure that money is actually reducing emissions effectively. And for data collectors like us on the CoolCalifornia team, inventories are necessary for data on baseline or default GHG emissions values. We like people who have thorough GHG inventories.

Sources: California Air Resources Board, California Climate Action Registry, ICLEI - Local Governments for Sustainability, and the Climate Registry. Local Government Operations Protocol for the quantification and reporting of greenhouse gas emissions inventories, Version 1.1.