Preliminary 2025 GHG inventory: Palo Alto posts big long‑term declines but methodology change clouds year‑to‑year picture

Christina Watts of sustainability management (S7) previewed the city’s preliminary 2025 greenhouse‑gas inventory and said staff used the global protocol for community‑scale inventories. "Preliminary calculations show that in 2025, Palo Alto emitted an estimated 406,607 metric tons of carbon dioxide equivalent," Watts said, and she noted that figure represents a 49.1% decrease from the 1990 base year despite a 20.5% population increase.

Watts explained the inventory uses a generation‑based approach grouped into stationary energy, transportation and waste, and she emphasized transportation remains the largest source of emissions — roughly 64% of the community total. She told the committee that per‑capita emissions were about 6 metric tons in 2025 compared with 14.3 metric tons in 1990, which aligns with California Air Resources Board targets for 2030 per‑capita levels. Watts cautioned that a change in vehicle emissions factors from the CARB database made on‑road emissions appear higher in 2025 even as electric‑vehicle adoption increased.

Committee members pressed staff to present an "apples‑to‑apples" comparison using the previous emissions factors to highlight real progress in EV adoption and to avoid public confusion. One member recommended leading with the apples‑to‑apples comparison in public materials and then noting the methodological rebaselining; staff agreed to include that comparison and additional context in the packet for the full council.

Watts said municipal inventory work was still being finalized and will return to full council in the fall with additional municipal analysis. The committee requested further detail on the drivers of an 8.1% rise in commercial natural‑gas emissions and on the modeled EV miles‑traveled assumptions; staff said they would follow up with data and the new Google Environmental Insights Explorer data when it becomes available.

What happens next: staff will prepare an apples‑to‑apples comparison for council, provide follow‑up on commercial natural‑gas drivers and make per‑capita metrics explicit in the final presentation to council.