Data Source: California Air Resources Board, California Greenhouse Gas Inventory - by Economic Sector and Activity
Analysis by CEC Economics
Highlights
- The transportation sector remains the largest-emitting sector in California, albeit its share of emissions fell slightly from 38.7% of total emissions in 2022 to 38.1% in 2023. However, the share of emissions from transportation is under 30% in the United States overall.4 The higher share of transportation emissions in California can be attributed to longer driving distances. In addition, California’s grid is also cleaner than the U.S. average so electric power sector emissions are a smaller slice of overall emissions in California, leading transportation to account for a relatively larger share of the total than it would if California’s grid pollution was closer to the national average. The industrial sector—a very difficult to decarbonize sector—is the next largest-emitting sector, making up 21.8% of California’s GHG emissions in 2023.
- Light-duty vehicles, the largest-emitting subsector within transportation that consists of passenger cars, light-duty trucks and SUVs, and motorcycles, totaled 100.5 MMTCO2e and accounted for 27.9% of California’s emissions in 2023. This is up slightly from 27.2% in 2022 but it has remained relatively unchanged over time. Since total emissions fell faster, the subsector’s share of emissions rose in 2023 despite a 0.6% (-0.6 MMTCO2e) reduction from 2022 to 2023.
4 The U.S. Environmental Protection Agency (EPA) had drafted but not published its Inventory of U.S. Greenhouse Gas Emissions and Sinks for 2023, although it solicited public comments for its draft in early 2025. Information on the EPA’s Inventory of GHG Emissions and Sinks is available at: https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks
Opportunity
- The next-largest on-road transportation emissions sector—the heavy-duty vehicles subsector—has been the main contributor to the drop in GHG emissions from on-road vehicles since 2018. Even as pandemic restrictions were lifted, the heavy-duty vehicles subsector GHG emissions did not rebound to the pre-pandemic level. After falling by over 10% from 2021 to 2022, the subsector’s emissions fell another 17.2% (-4.8 MMTCO2e) from 2022 to 2023. Compared to 2006, the year AB 32 became law, the sub-sector’s emissions have decreased by 45.3% (-19.1 MMTCO2e) and its share of total emissions decreased from 7.5% in 2022 to 6.4% in 2023. The reduction in emissions from heavy-duty vehicles corresponds to an increase in the use of biofuels in lieu of petroleum diesel under the state’s Low Carbon Fuel Standard (LCFS).5 The bio-component percent in diesel used by heavy-duty vehicles increased from 40.8% in 2022 to 55.8% in 2023. In 2018, when emissions from this subsector started to significantly decline, it was 13.8%.
5 The LCFS has a target to achieve a 20% reduction in Carbon Intensity by 2030 from a 2010 baseline by setting a declining annual target, or compliance standard. According to CARB, the state has already achieved a 19.8% reduction in 2024 from the 2010 baseline, or almost six years ahead of schedule. CARB’s LCFS dashboard can be accessed at: https://ww2.arb.ca.gov/resources/documents/lcfs-data-dashboard
Challenge
- Emissions from the residential sector have been trending in the opposite direction, making up 9.6% of total emissions in 2023, up from 8.8% in 2022 and 6.5% in 2006. After a moderate increase from 2021 to 2022 (+0.4%), this represents an increase of 2.2 MMTCO2e (+6.8%) from 2022 to 2023.
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