G4.1 Emissions inventory
Prepare and publish an annual emissions inventory that tracks greenhouse gas emissions by jurisdiction and source category. Review and update emissions inventory methodology as necessary to address improvements to data or methodologies, improve consistency, incorporate changes to state or federal policies, or report on issues of local interest.
Our current county emissions inventory, done in accordance with the ICLEI – Local Governments for Sustainability protocol, includes emissions produced within the county from on-road transportation, energy used in the built environment (including outdoor lighting), solid waste and wastewater, and agricultural livestock. It includes the emissions form electricity produced outside the county, but it doesn’t include the emissions outside the county associated with producing our food, or goods and services. (In part, this is to avoid double counting; we don’t want to count the emissions from making something as production emissions in one inventory somewhere and as consumption emissions in another inventory if we’re ever going to use the results together.) There are some preliminary estimates of the relative importance of some other local sources of emissions toward the end of the inventory.
The transportation inventory doesn’t count on-road emissions from vehicles simply passing through the county, even if they buy gas in Olympia, and it only counts tailpipe emissions, not the emissions involved in producing the fuel. If a truck is driven from a Seattle warehouse to deliver groceries here, the inventory only counts the miles inside the county. If I drive to Seattle and back, or to Los Angeles and back, it counts the miles from my house to the county line and the miles from the line to my house on the way home, but not the emissions from the rest of my trip. Conversely, of course, if someone drives to work here from Tacoma five days a week, our inventory counts the emissions from their miles inside Thurston County, but not the rest. (TRPC estimates that in 2010 the County had roughly 18,000 inbound commuters, and roughly 32,000 outbound commuters, so we had roughly 14,000 more outbound commuter trips a day where residents’ miles outside the County are not included than inbound trips where non-residents’ miles are included.) An expanded scope for our on-road transportation inventory would include additional emissions from commercial vehicles, long trips, and commuting.
The latest version of the ICLEI protocol (1.2) includes two appendices on estimating consumption based emissions associated with the community’s use of materials and services (Appendices H and I), and one for estimating emissions associated with forest lands and trees (Appendix J). Some jurisdictions, including King County, include their own consumption based inventories in their climate action planning. The Cool Climate project at Berkeley has also produced an estimate of emissions by zip-code that includes those from food, goods, and services.