Data Source: California Air Resources Board, California Greenhouse Gas Inventory - by Sector.
Analysis by CEC Economics
Highlights
- In 2023, GHG emissions from the transportation sector fell by 4.6% (-6.6 MMTCO2e) compared to 2022. Within the transportation sector, on-road vehicles emissions, which make up 90% of transportation’s emissions, were 4.2% (-5.4 MMTCO2e) lower in 2023 than in 2022. Within the on-road vehicles sub-sector, emissions from passenger vehicles fell by 0.6 MMTCO2e (-0.6%) from 2022 and the heavy-duty vehicles sub-sector fell by 4.8 MMTCO2e (-17.2%), another impressive double-digit percentage decline. Emissions from other transportation subsectors (aviation, rail, ships sub-sector, other and not specified) also had notable emissions reductions, falling by 1.2 MMTCO2e (-8.4%) compared to 2022.
- As a share of total emissions, the transportation sector was 38.1% in 2023, down from 38.7% in 2022. It is also only slightly higher than the 37.8% observed in 2020, when the sector’s emissions fell significantly due to the pandemic shutdown. The majority of the recent decreases in transportation sector emissions came from the heavy-duty vehicles sector, which fell by over a quarter (-8.6 MMTCO2e or -27.1%) in just two years from 2021.
- Emissions from distillate (diesel) fuel combustion from heavy-duty trucks accounted for the lion’s share of the reduction in heavy-duty vehicle subsector’s emissions, falling 27.1% (-5.1 MMTCO2e) in 2023 from 2022, which is an even bigger reduction compared to the 4.0 MMTCO2e (-17.6%) from 2021 to 2022. This reduction is likely attributed to the increased use of biofuels (renewable diesel and biodiesel) in lieu of petroleum diesel driven by the state’s Low Carbon Fuel Standard (LFCS).11 The bio-component percent in diesel used in heavy-duty vehicles increased from 29.8% in 2021 to 40.8% in 2022 to 55.8% in 2023. Other factors may include improved technologies, more efficient fuel usage, or regulations aimed at reducing emissions from heavy-duty diesel vehicles. CARB aims to meet California's air quality standards and greenhouse gas emissions reduction goals, with a focus on achieving 100% zero-emission transportation by 2035 for off-road transport refrigeration units (TRUs) and drayage vehicles, and 2045 for all other heavy-duty vehicles.12
11 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
12 The California Air Resources Board (CARB). New California requirements for heavy-duty vehicles and TRUs. Available at: https://ww2.arb.ca.gov/new-california-requirements-heavy-duty-vehicles-and-trus
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