Kendra Leon Barrionuevo

(CN) — To see if electric vehicles actually lower carbon emissions — especially in a region like California's Bay Area, with its particular dedication to environmentally-conscious traveling — a University of California, Berkeley team needed to work on the gaps in current research.

About 70% of global carbon dioxide emissions come from cities, but few urban areas have specific, localized data about where exactly those emissions come from, according to researchers in a study published Thursday in Environmental Science and Technology.

Dissatisfied with the lack of data, UC Berkeley professor of chemistry Ronald Cohen set up a network of sensors throughout the Bay Area in 2012. Cohen, graduate student Naomi Asimow and their team eventually set up over 80 stations that stretched from Sonoma County through Vallejo and down to San Leandro, according to the study.

Through this work, the researchers' 57 sensors recorded a steady decrease in CO2 emissions between 2018 and 2022, which the they said translated to a 2.6% yearly decrease in vehicle emission rates.

Researchers usually estimate CO2 emissions from known sources of carbon, but Asimow and Cohen said that this method does not predict small but significant downward trends in CO2 emissions.

To address that deficiency, the sensors in their Berkeley Environmental Air Quality and CO2 Network, or “BECO2N,” measure five critical air pollutants — carbon monoxide, nitrous oxides, ozone and particulates. Then, the team’s estimates combined direct CO2 measurements with meteorological data to calculate ground-level emissions to pick up the modest downturn in CO2 levels.

Cohen and Asimow also analyzed California's data for the very high electric vehicle adoption in the Bay Area to find the link between carbon emissions and electric vehicles.

“We used a combination of observations of CO2 and the weather to determine how total emissions have changed over time,” said Cohen via email. “We then interpreted that total as the sum of transportation, industrial and home/commercial natural gas use — mostly cooking, heating and hot water.”

This progress helps California in reaching its net zero emissions goal, but the team thinks that the state could do better.

“The state of California has set this goal for net zero emissions by 2045, and the goal is for 85% of the reduction to come from actual reduction of emissions, as opposed to direct removal of CO2 from the atmosphere,” said Asimow. “What we report is around half as fast as we need to go to get to net zero emissions by 2045.”

According to Cohen, the state would need to decrease CO2 emissions by 3.7% per year instead of the current 1.8% per year, and then California would need to sustain that rate for 20 more years.

Fueled by the team's findings, Cohen is intent on spreading their sensor system beyond the Bay Area, noting that pilot programs in Los Angeles, California, Providence, Rhode Island and Glasgow, Scotland are now underway.

Cohen pointed out that the sensors cost less than $10,000 each, whereas the Environmental Protection Agency operates pollution monitoring stations that cost 20 times as much. And while they are not available yet, Cohen hopes that future satellites could monitor CO2 levels across wide areas and with more granularity based on the team's current work.

“We show that you can make observations and measure changes due to policies of all kinds in a cost-effective and relatively rapid way,” said Cohen. “The network involves about half a million dollars' worth of equipment — a one-time investment — and a person per year thinking about it. One of our goals is to demonstrate, both on the CO2 and the air quality side of what we do, that this is cost-effective and translatable and easily accessible to the public in a way that nothing else is.”