New data shows biobased diesel comprised 56% of California’s on-road diesel fuel in 2023

The latest edition of the California's greenhouse-gas (GHG) emissions inventory shows a 3 percent drop in statewide emissions—the third-largest annual percentage decrease since the pandemic.  

The decrease is equivalent to removing more than 2.6 million gasoline-powered cars from California’s roads for one year.    

“Today’s milestone once again confirms that bold climate action can deliver real results,” said Lauren Sanchez, chair of the California Air Resources Board. “California’s climate pollution is falling even as our economy grows—a powerful testament to the strength of our programs, innovation in clean technology and the commitment of communities across the state. We’re not just investing in a healthier future, we’re actively building it.”  

The drop was primarily driven by reductions from the transportation sector, specifically a dramatic 17 percent decline from heavy-duty trucks due to the increased use of biofuels driven by the state’s Low Carbon Fuel Standard.  

Renewable diesel and biodiesel accounted for 56 percent of the diesel used on-road in 2023. 

The latest data underscores a continued trend of steady emissions decline even as the economy continues to grow, CARB stated.  

From 2000 to 2023, GHG emissions fell by 21 percent while California’s gross state product increased by 81 percent, pointing to the effectiveness of the state’s climate-change and air-quality programs, according to CARB.  

“The latest data show that science-driven policy and innovation are moving California closer to our climate goals,” said Yana Garcia, California’s secretary of environmental protection. “Emissions are down, cleaner trucks are on the road and communities are breathing healthier air. Access to reliable data isn’t just the foundation of progress. It’s how we hold ourselves accountable and make smart choices for the future. As the Trump administration moves to weaken national emissions reporting, California will continue to lead with transparency, integrity and results.”  

An early estimate of 2024 data, based primarily on reported and third-party verified data for the state’s largest emitters, shows that the downward trend will continue.  

The 2024 inventory data is not yet final and will not be released until 2026 once all data sources are updated and incorporated.  

Highlights from the report include:

• Emissions from cars and light-duty pickup trucks dropped to their lowest levels on record—excluding the anomaly of 2020 during the COVID-19 pandemic—as fossil fuel use continued to decline. 

• This drop occurred despite a 1 percent increase in vehicle miles traveled. Emissions from the state’s heavy-duty diesel vehicles also declined.  

• California has decreased the carbon intensity of its economy by 57 percent since 2000.  

• The electricity sector had its lowest carbon intensity since 2000. Wind and solar represent over 30 percent of generation and in-state solar increased by 8 percent from 2022, driven by requirements under the state’s Cap-and-Invest Program, also known as Cap-and-Trade and the Renewables Portfolio Standard.   

• Industrial-sector emissions declined by 5 percent due to reductions from refineries, oil and gas extraction, cement manufacturing, cogeneration facilities, and other fossil-fuel use.    

• Livestock emissions, which are responsible for 71 percent of agriculture’s GHG emissions, peaked in 2012 and continued to decline in 2023. The decrease is driven by use of methane digesters at dairies funded by Cap-and-Invest auction money and incentivized by the LCFS.   

• The residential and commercial sector had a rise in emissions, largely because of an increase in residential fossil-gas use, which was likely due to a colder winter in 2023.   

The statewide inventory relies on data from the Mandatory Reporting Regulation, which counts emissions and reductions from about 80 percent of California’s sources of human-caused climate emissions.  

It uses data from other state and local agencies to round out that picture.   

The announced plans to end federal monitoring of GHGs will not affect California’s inventory.