Problems accessing GHG source data (e.g., utility or vehicle miles traveled (VMT) data) cause long delays in developing, updating, and monitoring GHG inventories.
Developing greenhouse gas (GHG) inventories present significant administrative, financial, and technical burdens for many jurisdictions. There are typically roughly 23 data sources that go into a greenhouse gas inventory. The number crunching required is extremely time consuming, especially on a one-off basis. Any GHG emissions inventory developed for CEQA purposes needs to be legally-defensible.
Participants note burdensome procedures for accessing the data as a major issue, as well as data cleaning. Of the needed data sources (see Figure 1), participants indicate that the most challenging data sets are utility data and VMT data.
According to the ICLEI US Community Protocol & the Global Protocol for Community-Scale Greenhouse Gas Emission Inventories, GHG sources and methods should be: 1) relevant, 2) accurate, 3) complete, 4) transparent, 5) consistent (over time), and also 6) accessible (this has implications for cost and availability). However, participants relayed that the sources and methodologies change all the time and are difficult to reconcile and keep up to date with; also, the wide range of methods in use means one cannot compare across neighboring regional jurisdictions
Local governments have called for transparent, consistent, and affordable data. Various tools exist but there are challenges. None share a consistent methodology that ensures inventories are comparable across jurisdictions and across communities. Some of the tools are not freely accessible. Some rely on data sets that are not relevant to local jurisdictions and are thus not useful in the CAP development process. Private tool providers may want to keep some data private and proprietary, which limits transparency and utility. Attendees suggest preferred tool providers should offer up-to-date and regular maintenance; follow accepted protocols; no black-box calculations; use local datasets and emission factors; demonstrate subject matter expertise, and be consistent across methodologies and jurisdictional boundaries.
View the details on what communities have shared with SLECC from across the state.
Data must be aggregated/scrubbed to preserve privacy per 15/15 rule, a risk/liability to local governments, which also masks subsector information sometimes needed at a small-scale local level.
Participants highlighted tensions around climate inventory methods — while some argued that traditional community inventory protocols should be updated to use more accessible and meaningful data sources, others emphasized the need for consistency to track performance over time. Overall, participants agreed that the pursuit of perfect accounting can hinder progress, suggesting that flexibility and practicality should take precedence over precision.
For Vehicle Miles Traveled – State’s Scoping Plan uses fuel consumption/sales data for the statewide GHG inventory. This is difficult to reconcile with local approaches, which have to consider attribution within their jurisdiction. Local governments need to understand transportation behavior/trip patterns that a local jurisdiction can actually influence.
SLECC stakeholders have brainstormed the following solution opportunities that can be taken by local leaders. Existing examples of progress or pathways to make further progress are highlighted if known.
Develop a consistent, scalable approach for local transportation emissions accounting by leveraging existing regional and state data sources.
Inventory data solutions may be provided by the State, academic institutions, nonprofits, consultants, or regional agencies. All need to be willing to open up the black box of data to be transparent.
Strengthen regional data partnerships. Collaboration with universities (e.g., UC Riverside) and COGs participating in the Fifth Assessment can help translate complex datasets for practical local application, ensuring smaller cities aren’t left behind.
SLECC stakeholders have brainstormed the following solution opportunities that can be taken by state leaders. Existing examples of progress or pathways to make further progress are highlighted if known.
Enhance public access and coordination of climate data resources. Integrate and streamline climate data tools across universities and agencies, ensuring key datasets are updated frequently and made easily accessible to support local planning and decision-making.
Conduct Analysis on Available Tools and Resources: A comparative analysis on existing GHG inventories, as proposed by CARB, could be valuable. It should assess all available and pending tools and evaluate factors that will make a tool valuable to local governments such as: transparency, consistency across jurisdictions and with leading GHG protocols, defensibility, and likelihood that a government entity will consider the tool provider and its data as credible and unbiased.
Improve upon the Local Climate Action Plan Protocols: This adjustment would make the process of GHG inventory development easier, more standardized, more replicable. Ideas include establishing a best practice guide or manual for developing inventories, targets, and/or reduction strategies
The Bay Area Energy Atlas—one of the nation’s most comprehensive energy tools—has been revamped with new features, expanded data, and a more user-friendly interface. Developed by UCLA in partnership with BayREN, the Atlas helps users explore regional energy use through interactive maps and detailed building data. From policymakers to curious residents, anyone can now dive deeper into energy trends by city, building type, or time period. New tools make it easier to compare communities and visualize consumption with monthly data through 2021.
The CoolClimate Network at UC Berkeley is developing a data platform for GHG inventories and climate action metrics for local governments across California. The project was presented at CCEC 2024 and 2025 to gather input from participants. The outputs available to cities and counties (unincorporated counties are in the works) include traditional and consumption based inventories from 2010-2022. They also feature tangible metrics such as EV registrations with the DMV and heat pumps installed through TECH incentives. These detailed metrics are more informative and actionable for implementation than overall GHG emissions. They enable local governments to set concrete targets and tell compelling stories about climate action, benefits, and potential impacts in their communities. The emphasis on these metrics reflects the emerging trends of climate action practice, which seeks to be more relatable to people and integrated with equitable community benefits.
The climate action data tool allows local governments to more efficiently conduct GHG inventories and evolve their climate action efforts and communications to focus on community benefits. The practice of local government climate action was originally established in the mid 2000’s in response to a lack of federal leadership. The current context calls us not only to continue but become more effective while delivering quantifiable social benefits and having the metrics to tell compelling stories.
CARB staff and contractors participate in the project’s advisory group and are evaluating whether this tool will meet the needs of local governments.
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