Estimating Policy-Driven Greenhouse Gas Emissions Trajectories in California: The California Greenhouse Gas Inventory Spreadsheet (GHGIS) Model

For decades, California has used groundbreaking tools to collect and analyze emissions data from a variety of sources to establish a scientific basis for policy making. As its scope has expanded to include greenhouse gas (GHG) reductions, it has sought out similar tools to use to achieve the goals of legislation such as the Global Warming Solutions Act of 2006 (AB 32).

To support this effort, Lawrence Berkeley National Laboratory developed a California Greenhouse Gas Inventory Spreadsheet (GHGIS) model funded by the California Air Resources Board (ARB), to explore the impact of combinations of state policies on state GHG and regional criteria pollutant emissions. This Excel-based model includes representations of all the GHG-emitting sectors of the California economy, and it was calibrated using data and projections from state agencies and other sources. The model also calculated emissions of three criteria pollutants—reactive organic gases, nitrogen oxides (NOx), and fine particulates—statewide and for the South Coast Air Basin (SCAB) and the San Joaquin Valley (SJV).

The project modeled three scenarios: (1) all committed policies, (2) additional, uncommitted policy targets, and (3) potential technology and market futures.

Results indicate that for all three scenarios California would be able to meet the 2020 statewide GHG targets, and by 2030, a plausible range of statewide GHG emissions falls between 208 and 396 megatons of carbon dioxide equivalent per year (MtCO₂e/yr). However, the modeling revealed that the state will be unable to meet the 2050 GHG target of 85 MtCO₂e/yr under any of the scenarios, so additional policies will need to be developed to meet this stringent target. In all three scenarios, results showed that criteria pollutants were significantly reduced statewide and in the two regional air basins; however, they may not meet future federal standards. In particular, NOx emissions were significantly above the estimated targets.

Greenblatt, Jeffery B. 2013. Estimating Policy-Driven Greenhouse Gas Emissions Trajectories in California: The California Greenhouse Gas Inventory Spreadsheet (GHGIS) Model.