Consultants present draft community greenhouse-gas inventory showing transport, natural gas as largest sources

Cascadia consultant Jenna Decker Sherry told the City of Lake Forest Park Climate Planning Advisory Team (CPAT) that a draft community-wide greenhouse-gas inventory for 2019, 2022 and 2023 and a separate 2023 municipal inventory are underway to inform the city’s climate element.

The inventory uses locally specific utility consumption where available and regional or national datasets where local data are not available. "I do want to stress that this is a draft, so these numbers are subject to change," Decker Sherry said. She said the team prefers locally specific data and follows the U.S. Community Protocol for estimating greenhouse-gas emissions when scaling to regional datasets.

The presentation listed the primary emissions sources and the data sources being used: building energy (electricity, natural gas, fuel oil, propane) using local utility consumption or Washington-specific EIA data; on-road transportation using the PSRC transportation model and a vehicle‑miles‑traveled (VMT) study by a subconsultant to ground-truth allocations; off-road emissions scaled from King County EPA MOVES data; aviation allocations based on origin-destination allocations to King County; solid‑waste tonnage from King County; land‑use (tree loss/gain) estimated with a GIS shapefile run through an IGLIA/learn model; and refrigerants scaled from a national EPA dataset by population.

Decker Sherry said preliminary draft results show on-road transportation and building natural gas as the largest emission sources in 2023, and an overall downward trend in the city’s emissions since 2019. She said the largest single driver of the decline between 2019 and 2023 is a 43% reduction in aviation emissions allocated to King County in the dataset used, citing a drop in jet fuel consumption and a smaller share of origin trips allocated to King County.

During questions, CPAT members pressed how locally specific changes (for example, increased heat‑pump adoption or local EV uptake) will show up in future inventories. Decker Sherry said the team will use local consumption data where available (electricity and natural gas kilowatt‑hours/therms, and on‑road VMT within the city boundary). For sources that lack local records — refrigerants and some off‑road equipment — the team must rely on scaled national or county datasets but will model local policy scenarios in a later emissions‑reduction forecast.

Decker Sherry said the project team plans follow-ups: a municipal and community‑wide inventory update on March 12, and final inventory results and the emissions‑forecast model on April 15. She invited CPAT members to provide questions and noted the inventory and forecast will be used to model the emissions impacts of local actions.

The CPAT discussion clarified that the inventory reports total VMT occurring within Lake Forest Park’s geographic boundary regardless of whether drivers live in the city or are passing through, and that some emission categories are necessarily less localizable than others. The team also confirmed the inventory years (2019, 2022, 2023) and that 2019–2023 comparisons reflect sectoral and dataset changes rather than only local policy shifts.

The next presentation on climate policy and the policy audit followed; the inventory team will return to CPAT with updated drafts in March and final results in April.