California greenhouse gas emissions in transport sector down sharply

The transportation sector showed the largest decline in greenhouse gas emissions in California in 2020 compared to other sectors, according to a California Air Resources Board report.

CARB recently released a report titled “California greenhouse gas emissions for 2000 to 2020: Trends of emissions and other indicators.” In it, the board breaks down greenhouse gas emissions over the past two decades. In 2020, emissions statewide were 369.2 million metric tons of carbon dioxide equivalent, which is 35.3 million metric tons lower than 2019 levels.

The transportation sector had the largest decline in greenhouse gas emissions in 2020 at 27 million metric tons. According to the report, the transportation sector is the largest source of emissions in the state, accounting for 37% of statewide emissions in 2020, which is a smaller share than in recent years.

Of that 37% in greenhouse gas emissions, 25% came from passenger vehicles while only 9% coming from heavy-duty vehicles.

Emissions from transportation sources peaked from 2002 to 2007, then steadily decreased until 2012, when transportation sector emissions began to rise again. Emissions from this sector have declined for three consecutive years since 2017, with 2020 having the largest emission change.

According to the report, biodiesel has played an important role.

“The percentages of biodiesel and renewable diesel in the total diesel blend have shown significant growth in recent years, growing from 0.4% in 2011 to 20.8% in 2020, due mostly to the implementation of the Low Carbon Fuel Standard,” the report stated. “Without biofuels, California tailpipe fossil CO₂ would be 15 (million metric tons) higher in 2020.”

However, there is a caveat.

CARB points out that “this decrease was most likely from light-duty vehicles after shelter-in-place orders were enacted in response to the COVID-19 pandemic.” In other words, 2020’s greenhouse gas emission numbers are likely an anomaly.

“As such, the total 2020 reported emissions are likely an anomaly, and any near-term increases in annual emissions should be considered in the context of the pandemic,” the report stated.

Since the peak level in 2004, California’s greenhouse gas emissions have been trending downward. In 2014, statewide emissions dropped below the 2020 limit and have remained below the limit since then. LL