Reporter’s Notebook: Drivers in San Diego have a bigger carbon footprint than motorists in Los Angeles. At least on paper.

San Diego drivers are believed to create nearly double the greenhouse gases compared to driving Angelinos.

That’s according to a comparison of city climate action plans, which estimated road transport before the pandemic dumped 5.8 million tonnes and 3.4 million tonnes of global warming emissions, respectively.

The results are shocking given that the city of San Diego is home to around 1.3 million people, while Los Angeles has over 3.8 million people.

“These numbers don’t make much sense given the difference in population and physical size,” said Ted Lamm, senior fellow at UC Berkeley’s Center for Law, Energy and the Environment. “I imagine that differences in public transport use, vehicle electrification rates, etc. may have some impact, but nothing of this magnitude.”

One explanation could be the different carbon accounting methods used by each city.

San Diego uses the Community Protocol for Accounting and Reporting of Greenhouse Gas Emissions, a standard tool recommended by the State of California. LA, on the other hand, has adopted the Global Protocol for Community-wide Greenhouse Gas Emissions.

“LA is the only U.S. city I’ve seen using this protocol, so it’s difficult to compare LA’s inventory with any other city,” said Juan Matute, deputy director of the Institute of Transportation Studies. from UCLA, which helped develop the method adopted by San Diego.

“I think the blame lies here in LA for doing their own thing,” he added. “San Diego is more like what I would expect from a climate action plan.”

The City of Los Angeles did not respond to multiple interview requests for this story. The City of San Diego confirmed that the use of different models was likely the cause of the discrepancy.