One of the many services offered by Sierra Nevada Energy Watch (SNEW) is the development of greenhouse gas (GHG) inventories. Creating a GHG inventory is a critical first step in the climate action planning process, providing a snapshot of emissions for a jurisdiction in a specific year and forming the foundation for meaningful emissions reductions.

A GHG inventory serves several key purposes. It can either establish a baseline which future inventories can compare emissions reduction over time, or help jurisdictions set realistic reduction targets and forecasting. A GHG inventory also identifies the sectors and sources contributing to emissions and their relative share of the total. These emissions are typically grouped into two categories: community-wide emissions and government operations. Community-wide emissions capture everything, while government operations are solely emissions from municipal-owned facilities and vehicles. Emissions from government operations are captured community-wide. These two categories are consistent with the ICLEI Local Government Operations Protocol, which is a widely trusted and standardized method that SNEW follows.

Developing a GHG inventory involves a structured and data-driven process. SNEW works with local jurisdictions to collect activity data across major sectors such as transportation, energy use, waste, and water. This data is then converted into emissions using standardized methodologies, including calculations from a specialized software ClearPath. The resulting inventory provides a comprehensive and consistent accounting of emissions.

This process not only ensures accuracy and transparency but also equips local governments with the information needed to prioritize actions. By understanding where emissions are coming from, jurisdictions can focus their efforts on the most impactful strategies. Many emissions reduction measures include co-benefits such as improved air quality and public health, so this information is useful in the budgeting process. There also may be grant opportunities that require GHG inventory data that could help fund various projects.

Recent GHG inventories developed by SNEW highlight several common trends across the region. In many jurisdictions, transportation remains the largest source of emissions, followed by energy use in residential and commercial buildings. Government operations typically represent a smaller share of total emissions but offer important opportunities for leadership through internal reductions. The main benefit of extrapolating municipal data is that jurisdictions often have complete control over their own operations and buildings. Thus, change can be easier to implement within government operations compared with change that impacts the whole community.

These findings help inform Climate Action Plans (CAPs), guiding strategies such as improving energy efficiency, increasing renewable energy adoption, and reducing transportation related emissions. Just as importantly, they help track changes in emissions over time. It is often recommended to conduct GHG inventories every 5-10 years or after large emissions reducing projects are completed.