EV adoption has brought modest, but measurable, declines in Bay Area emissions: Study

The adoption of electric vehicles (EVs) across the Bay Area has brought a small but steady decrease in carbon dioxide emissions to the region, a new study has found.

Using an air quality monitoring network set up in the area more than a decade ago, scientists documented a 2.6 percent annual decline in vehicle emissions rates over a five-year period. They published their results Wednesday in the journal Environmental Science & Technology.

The researchers amassed their data by using a network of air pollution monitoring sensors first set up in 2012 by Ronald Cohen, a University of California, Berkeley chemistry professor, who is also the senior author of the study.

Today, the Berkeley Environmental Air Quality and CO2 Network (BEACO2N) has expanded to more than 80 stations, including seven in San Francisco and on the East Bay, stretching from Sonoma County through Vallejo and San Leandro, Calif.

Combing through data from 2018 to 2022, the researchers found that 57 of the 80 sensors recorded a modest but meaningful decrease in carbon dioxide emissions — or about 1.8 percent annually.

When factoring in California data for EV adoption rates, that drop translated into a 2.6 percent yearly plunge in vehicle emissions rates, according to the study. 

“That’s 2.6 percent less CO2 per mile driven each year,” lead author Naomi Asimow, a graduate student in the department of Darth and planetary science, said in a statement.

While this decline is generally good news, it’s a far cry from the yearly decrease that the Bay Area and the rest of California would need to exhibit in order to meet long-term climate goals.

“The state of California has set this goal for net zero emissions by 2045, and the goal is for 85 percent of the reduction to come from actual reduction of emissions, as opposed to direct removal of CO2 from the atmosphere,” Asimow said.

“What we report is around half as fast as we need to go to get to net zero emissions by 2045,” she added.

The annual rate of decline in overall emissions needs to be 3.7 percent, rather than 1.8 percent, Asimow explained.

Although carbon dioxide releases are usually estimated based on known sources of carbon — such as how much gas is used in heating or fuel consumption and efficiency in registered vehicles — the authors said that taking such an approach did not indicate the emissions decline that they identified.

Their approach, instead, involved combining direct carbon dioxide measurements from the network sensors with meteorological data to calculate ground-level emissions.

Advocating for the installation of such sensors in other cities, Cohen said that they are inexpensive enough — less than $10,000 per sensor — that major metropolitan areas could deploy such a network and gain a clearer perception of their air pollution burden and the sources of those plumes.

“This is cost-effective and translatable and easily accessible to the public in a way that nothing else is,” Cohen said.