Research Projects

Central to any study of climate change is the development of an emission inventory that identifies and quantifies the State’s primary anthropogenic sources and sinks of greenhouse gas (GHG) emissions. In 2004, carbon dioxide (CO2) emissions from fossil fuel combustion accounted for 80 percent of California GHG emissions. Even though these CO2 emissions are relatively well characterized in the existing State inventory, significant sources of uncertainties regarding their accuracy still exist. This was a two-Phase research contract. The first part of the final report evaluates CO2 emissions based on the California Energy Balance Database (CALEB) developed by the Lawrence Berkeley National Laboratory (LBNL), in terms of what improvements are needed and where uncertainties lie. The estimated uncertainty for total CO2 emissions ranges between -21 and +37 million metric tons (MMT), or -6% and +11% of total CO2 emissions. The report also identifies where improvements are needed for the upcoming updates of CALEB. However, it is worth noting that the California Air Resources Board (CARB) GHG inventory did not use CALEB data for all combustion estimates. Therefore the range in uncertainty estimated in this report does not apply to the CARB’s GHG inventory. As much as possible, additional data sources used by CARB in the development of its GHG inventory are summarized in this report for consideration in future updates to CALEB.

The second part of this report allocates California’s 2004 statewide CO2 emissions from fuel combustion to the 58 counties in the State, using several different methods, based on the availability of data for each sector. The distribution of emissions by sector varies considerably by county, with on-road motor vehicles dominating most counties, but large stationary sources and rail travel dominating in other counties. Improving the CO2 emission estimates, finding ways of validating these on a sector-by-sector basis, and providing a validation approach to the statewide GHG emission inventory through disaggregation is an important step in building AB 32 GHG emissions inventory baselines and projections.