Bay Area Carbon Emissions Steadily Fall as Region Embraces EVs

The San Francisco Bay Area is leading the state and nation in a shift from gas-powered cars to electric vehicles. These EVs, as well as hybrid cars and other more fuel-efficient models, are steadily lowering the region’s carbon footprint, according to researchers at UC Berkeley.

The scientists found that carbon dioxide levels fell across the region at an annual rate of about 1.8% between 2018 and 2022. Vehicle emission rates saw a yearly drop of 2.6%. The scientists used data pulled from a custom-designed network of sensors affixed mostly to the top of schools in the East Bay to monitor carbon dioxide levels in real time, as well as state statistics and records from the DMV.

The idea for the sensors came from Ronald Cohen, a UC Berkeley professor of chemistry, who argued it is the first real-world evidence that the region’s bellwether adoption of electric vehicles is measurably lowering the Bay Area’s carbon emissions. In an interview with KQED, he said his team has shown that it’s technically possible to measure changes in carbon dioxide over time and at a granular, city-level, which could have significant real-world applications as localities across the world pass goals for reducing planet-warming gas emissions.

“One of the things we set out to do is to be able to report on changes within cities in a way of providing observational feedback on the efficacy of policy,” he said. “We’re excited about that.”

The research results were published Thursday in the American Chemical Society’s journal Environmental Science & Technology.

Emission reductions in California and elsewhere are often calculated using a system of accounting and estimates. Or with federal sensors that cost hundreds of thousands of dollars. Cohen said that his sensors cost less than $10,000 and offer cities a realistic window for tracking their sources of pollution. The devices also measure air pollutants, including tiny particles in wildfire smoke, carbon monoxide, nitrous oxides and ozone.

He said that he was “pleasantly surprised” to see the scale of the average reductions of carbon dioxide over time. California’s goal is to be carbon neutral by 2045, slashing air pollution by 71% in the process. To meet that goal, the state needs to reduce its emissions by 3.7% per year.

At least in the Bay Area, “we’re almost halfway there at our rate today,” Cohen said. “We do need to accelerate. But the starting point is pretty good right now.”

That’s a glass half full interpretation. Even the Bay Area, which Cohen said has roughly double the EVs of a city like Los Angeles, would need to increase its emissions reductions each year to be on pace with the state target.

The study “reminds us that we are not reducing emissions faster enough,” said Jens Mühle, a researcher at Scripps Institution of Oceanography at UC San Diego. He was not involved in the research.

However, he agreed that the network of sensors has shown a statistically significant drop in emissions in the Bay Area, and it is important to be able to accurately measure carbon pollution at that level.

Cities represent approximately 70% of global carbon dioxide emissions, and “oftentimes the impact of climate change is the worst [there],” he said. “You have all this concrete and asphalt, and you have the heat waves. They also have a potentially large impact on reducing global CO2 emissions, and that’s what they’re doing.”