The latest edition of California's greenhouse gas emissions inventory shows a 3% 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 California Air Resources Board (CARB) Chair Lauren Sanchez. “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."

According to a release, the drop was primarily driven by reductions from the transportation sector, specifically a dramatic 17% decline from heavy-duty trucks, due to the increased use of biofuels resulting from the state’s Low Carbon Fuel Standard (LCFS). Renewable diesel and biodiesel accounted for 56% of the diesel used on-road in 2023.

Steady Emissions Decline Amid Economic Growth

The latest data underscores a continued trend of steady emissions decline even as the economy continues to grow. From 2000 to 2023, GHG emissions decreased by 21%, while California’s gross state product increased by 81%, indicating the effectiveness of the state’s climate change and air quality programs.

“The latest data show that science-driven policy and innovation are moving California closer to our climate goals,” said California Environmental Protection Secretary Yana Garcia. “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, indicates 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 have been 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 2020 anomaly, which was attributed to the COVID-19 pandemic — as fossil fuel use continued to decline.

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

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

• The electricity sector had its lowest carbon intensity since 2000. Wind and solar represent over 30% of generation, and in-state solar increased by 8% 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% due to reductions from refineries, oil and gas extraction, cement manufacturing, cogeneration facilities, and other sources of fossil fuel use.  

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

The residential and commercial sectors experienced “a rise in emissions, largely due to an increase in residential fossil gas use, which was likely a result of the colder winter in 2023.”  

About the Inventory

The statewide inventory relies on data from the Mandatory Reporting Regulation, which counts emissions and reductions from about 80% 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 greenhouse gases will not affect California’s inventory.