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First evidence that electric vehicles measurably lower regional carbon emissions

An atmospheric chemist from the University of California, Berkeley, has established an extensive CO2 monitoring network across the San Francisco Bay Area. The network, consisting of more than 80 sensors, has recorded the first evidence that the adoption of electric vehicles is measurably lowering the area’s carbon emissions.

Mastermind behind BEACO2N

The network of sensors, most of them located in the East Bay, is the brainchild of Ronald Cohen, UC Berkeley professor of chemistry.

Cohen envisions inexpensive, publicly funded pollution and carbon dioxide monitors widely distributed around urban areas to pinpoint emission sources and the neighborhoods most affected.

With an estimated 70% of global CO2 emissions coming from cities, few urban areas have granular data about where those emissions originate.

In 2012, Cohen began setting up the Bay Area sensing network, known as the Berkeley Environmental Air Quality and CO2 Network (BEACO2N).

The network has now grown to more than 80 stations, including seven in San Francisco, stretching from Sonoma County through Vallejo and down to San Leandro.

Electric vehicles reduced carbon emissions

Between 2018 and 2022, 57 of the sensors in BEACO2N recorded a small but steady decrease in CO2 emissions — about 1.8% annually — that translates to a 2.6% yearly drop in vehicle emission rates.

Naomi Asimow, a graduate student in the Department of Earth and Planetary Science, along with Cohen, concluded that the decrease was due to passenger vehicle electrification based on California data for electric vehicle adoption, which is very high in the Bay Area.

“That’s 2.6% less CO2 per mile driven each year,” said Asimow.

The study, according to Cohen, demonstrates the utility of an urban network for monitoring and managing federal, state, and city mandates for CO2 reduction.

“We show from atmospheric measurements that adoption of electric vehicles is working, that it’s having the intended effect on CO2 emissions,” Cohen said.

Accelerated action desperately needed

Despite the good news, the yearly decrease needs to be much greater to meet California and Bay Area carbon reduction goals.

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

“We’re at 1.8% per year today. To get to the state’s goal, we would need 3.7%,” Cohen added. “So it’s not too much higher than where we are; we’re almost half of the way to that goal. But we have to sustain that for another 20 years.”

The results emphasize the urgent need for accelerated actions to reduce CO2 in order to achieve the ambitious zero emission targets that cities seek.

Power of carbon measurements in electric vehicle areas

One impetus for the study was to see whether the BEACO2N network could detect any downward trend in vehicle emissions since the state set goals for greenhouse gas reduction and the electric vehicle market has blossomed.

“We were curious if our data would show us our progress toward meeting California’s emissions goals,” Asimow said.

The UC Berkeley team’s estimates combined direct CO2 measurements with meteorological data to calculate ground-level emissions — an approach using atmospheric observations that did pick up the modest downturn in CO2 levels.

This method proved more effective than the traditional “bottom-up” method for estimating carbon dioxide emissions, which did not predict the small but significant downward trend.

Potential for widespread adoption

Cohen argues that his sensors are inexpensive enough — less than $10,000 per sensor, versus 20 times as much for pollution monitoring stations operated by the Environmental Protection Agency — that major cities could afford to install a network to get a more granular view of unhealthy areas and sources of pollution.

The network sensors also measure five critical air pollutants: carbon monoxide, nitrous oxides (NO and NO2), ozone, and particulates (PM 2.5).

“We show that you can make observations and measure changes due to policies of all kinds in a cost-effective and relatively rapid way. The network involves about half a million dollars’ worth of equipment — a one-time investment — and a person per year thinking about it,” Cohen said.

“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,” he concluded.

Synergy needed between ground and space monitoring

While satellites could monitor carbon dioxide levels across wide areas and with more granularity in the future, those satellites are not yet available, Cohen said.

“The optimal solution will be some combination of space-based assets and ground-based measurements,” he said.

Los Angeles, California; Providence, Rhode Island; and Glasgow, Scotland, have already adopted Cohen’s sensors to create their own pollution monitoring networks, paving the way for a cleaner, healthier future.

Electric vehicles, carbon emissions, and the future

In summary, the San Francisco Bay Area’s pioneering CO2 monitoring network has provided the first evidence that the adoption of electric vehicles is measurably lowering the area’s carbon emissions.

This very encouraging study demonstrates the effectiveness of atmospheric measurements in tracking CO2 levels while highlighting the potential for widespread adoption of affordable sensor networks in urban areas.

As cities around the world begin to implement similar monitoring systems, they take a crucial step towards a cleaner, healthier future. However, the results also underscore the need for accelerated efforts to reduce CO2 emissions and meet ambitious carbon reduction goals.

By combining ground-based measurements with future satellite monitoring, we can work towards a more comprehensive understanding of our impact on the atmosphere and take decisive action to combat climate change.

The full study was published in the journal Environmental Science & Technology.


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