City sustainability staff presented updated greenhouse-gas inventories developed for the King County Cities Climate Collaboration (K4C) and a city-specific geographic inventory for Sammamish, highlighting both progress since 2019 and remaining gaps to reach 2030 targets.

The inventories, prepared by Cascadia Consulting Group for the King County Executive Climate Office and partners, include consumption-based and geographic measures. Rose, the city’s sustainability staff member presenting the data, said the county’s consumption-based emissions were 47,300,000 metric tons of carbon-dioxide-equivalent (CO2e) for 2023, while the county’s geographic inventory totaled about 24,200,000 metric tons CO2e. "Geographic inventories look at emissions that occur within a boundary; consumption inventories include upstream emissions and typically produce larger totals," Rose explained.

At the Sammamish level, the presentation focused on "core emissions" (the sectors the city has most influence over): buildings & energy, transportation, and solid waste. Rose reported a 12% decrease in core emissions since the city’s 2019 baseline. Key sector notes included a decline in electricity-related emissions (attributed in part to reductions in electricity carbon intensity from power providers) even as natural-gas emissions increased. The transportation sector showed a 17% decrease in on-road vehicle emissions — a result attributed to fuel-economy improvements and relatively high electric-vehicle adoption among Sammamish residents. Solid-waste emissions remain a small share (~2%) of total community emissions but showed mixed trends: landfill emissions decreased from 2022 to 2023 yet remained higher than the 2019 baseline.

Commissioners pressed staff on methodology and attribution. Several questioned how aviation was allocated to cities; Rose noted aviation is often distributed across jurisdictions in the county-level analysis and that the K4C county reports used survey-derived allocations to distribute air travel emissions. Commissioners also asked about scope definitions; Rose explained the consumption-based inventory captures more upstream (scope 3) emissions while geographic inventories are closer to scope 1 and 2 reporting commonly used in municipal Climate Action Plans.

Looking ahead, staff presented a wedge-analysis projection showing that existing federal, state and regional policies — combined with proposed county actions — could reduce King County emissions by about 33% by 2030 under full implementation but still fall short of some local 2030 targets. Rose said the county is developing an attribution tool and supplemental analysis that will let cities explore allocations and drivers in more detail; the commission agreed to consider deeper dives at a January meeting to link the new data to the city’s implementation priorities.

The presentation provided both data and a policy conversation: commissioners welcomed the progress shown in per-capita and core-sector declines while emphasizing the need to connect those findings to tangible outreach, incentive and building-decarbonization efforts within Sammamish.