California, in so many ways, could learn from the US Northeast. 

To reduce CO₂ and and greenhouse gas emissions from cars, a continuing and increasing issue in California and elsewhere, cities need data—ways to accurately measure emissions, pinpoint sources, and monitor change over time; cities need to know how much CO₂ they are producing and reducing.

A tool called ACES (Anthropogenic Carbon Emissions System) was developed in response to the requirement for data by researchers at Boston University and Harvard. ACES offers finely-grained maps of CO₂ emissions, with a resolution of 1km2, totaled hourly.

As we know, per our atmosphere – the air, its particular mix of gaseous elements, and its temperatures, together vital to life, inclusive of human, animal, and plant – CO₂ and other greenhouse gases are an issue, in many ways.

California has “targets” to meet by the year 2020 for limiting the greenhouse gases associated with the driving that people do on a daily basis. The approach to greenhouse gases associated with the driving that people do on a daily basis has a heightened level of complexity in California. Driving a car, rather than availing oneself of public transportation such as a subway, metro, or bus, is a norm that people are highly unwilling and actually afraid to examine and rethink. The many localities within the state have made limited investment in public transportation in significant part because taking such modes of transportation is largely considered to be beneath the dignity – whether personal, social, or professional – of and compromising to anybody with a sense of self esteem.

While the “hope” has been that climate emissions might be curbed largely by promoting regional planning of denser development along transit lines ( S.B. 375, the Sustainable Communities and Climate Protection Act, a landmark 2008 deal, with the California legislature recognizing the critical role of integrated transportation, land use, and housing decisions to meet state climate goals), the California Air Resources Board 2018 Progress Report released in November documents that driving of cars has skyrocketed statewide during the years following the recession of 2008 – 2009 through 2016.

A “key finding of this report is that California is not on track to meet the greenhouse gas reductions expected under SB 375 for 2020, with emissions from statewide passenger vehicle travel per capita increasing and going in the wrong direction” (page 4) and “emissions from the transportation sector continuing to rise despite increases in fuel efficiency and decreases in the carbon content of fuel” (page 5).

Top air quality officials in California state they currently have no way to fully assess whether regions from San Diego to Sacramento are on track to meet 2020 targets for reigning in greenhouse gases associated with daily driving. While “greenhouse gas emissions considered under the SB 375 program reflect carbon-dioxide (CO₂) emissions only from light-duty passenger vehicles” (page 21, footnote 22), the California Air Resources Board 2018 Progress Report states, “SB 375 passenger vehicle greenhouse gas emissions reductions cannot be directly measured because greenhouse gas emissions come from many sources” (page 21).

Air board officials said that while they tracked the key metric of vehicle miles traveled, or VMT, available statewide through fuel sales, that same information wasn’t available regionally. Without that, officials say there is no consistent way to extrapolate greenhouse gas emissions from driving for each region.

“There’s no unifying way to bring it all together and say ‘You’re at this particular performance metric,’” said Nicole Dolney, chief of the air board’s transportation planning branch. “Our hope was that we would have VMT data that we could rely on, but it wasn’t there.”

So what might California learn from ACES?

“For cities to cut down CO₂, they need to know how much they are producing and reducing. Most cities get rough estimates with “carbon calculators” that account for the size and population of a city, electricity used, and an estimate of how many cars zip (or crawl) through the city streets.

“The calculation would be fine except for all those cars. Cars are the hardest part of the emissions equation to quantify. They are moving all the time at different speeds, and there are different cars on the road at different times of day.”

“There are other factors to consider. There’s the make of the car, of course: a Toyota Prius gives off less CO₂ than a Chevy Silverado. There’s also the speed; most cars give off the least CO₂ when cruising in a “sweet spot” between 40 and 60 miles per hour.”

(Conor Gately, co-developer of ACES; PhD, Geography and Environment, Boston University, 2016; lead author on a study examining cities, traffic, and CO₂, published in the Proceedings of the National Academy of Sciences (PNAS) in April 2015.)

ACES (Anthropogenic Carbon Emissions System) has been developed by Lucy Hutyra of Boston University and Conor Gately, now a postdoctoral associate working jointly at Boston University and Harvard. A tool for measuring and mapping CO2 emissions, ACES offers finely-grained maps of CO2 emissions, with a resolution of 1km2, totaled hourly, is relevant and could be helpful to the cities and the state of California.

“Cities have the political will to change emissions, and they have policy levers to pull,” says Lucy Hutyra, a Boston University College of Arts & Sciences (CAS) associate professor of Earth and environment. And because cities are responsible for 70 percent of greenhouse-gas emissions, according to the United Nations, their actions matter. But to take effective action, cities need data—ways to accurately measure emissions, pinpoint sources, and monitor change over time. And so Hutyra and her colleague Conor Gately have developed a tool called ACES, for Anthropogenic Carbon Emissions System, that offers the finest-grained maps of CO2 emissions in the Northeastern US to date, with a resolution of 1km2, totaled hourly. The tool, funded by NASA’s Carbon Monitoring System and detailed in the October 12, 2017, issue of the Journal of Geophysical Research—Atmospheres, could provide valuable data to cities nationwide.

“‘The goal was to take the finest grained, most local data possible and build a ‘bottom-up’ inventory,” says Gately. The research team started by divvying up the sources of emissions on a giant whiteboard. “We did every sector of emissions of CO2,” he says. “Roads, residential buildings, commercial buildings, industrial facilities, power plants, airports, marine ports, shipping, and railway.” The group searched for data from 2011, scouring every source they could find: city and country records, household fuel estimates, EPA databases, hundreds of traffic sensors located around New England. All of these data, when combined with the amount of fossil fuels consumed in the region (gasoline, diesel, home heating oil, coal and natural gas for power generation), allowed the team to calculate CO2 emissions for all of the major sources. The team then calculated emissions for every hour of the year.

“Gately, working with a three-year, $1.5 million grant from the National Oceanic and Atmospheric Administration, is now expanding ACES to cover the entire continental United States and meeting with government, scientific, and policy stakeholders to help create a core set of methods and data products.”

DARTE might also be helpful. DARTE, the Database of Road Transportation Emissions (Conor Gately, Lucy Hutyra, Ian Sue Wing) is available for free download from the Harvard Dataverse

Funded by grants from the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the Department of Energy (DOE), Gately has developed a more precise way to tally CO₂ emissions from vehicles. He used 33 years of traffic data to build the Database of Road Transportation Emissions (DARTE), which displays CO₂ data for the contiguous US on a finer scale than ever before—a one-kilometer grid. (He hopes to add Alaska and Hawaii later.) Available for free download, DARTE could change the way cities and states measure greenhouse gas emissions.

“The science is coming together to bring us very fine measurements in a way never possible before,” says Lucy Hutyra, an assistant professor of earth and environment and a coauthor on the PNAS study. Hutyra says that DARTE complements NASA’s Orbiting Carbon Observatory 2, which is collecting global data on atmospheric carbon dioxide. “We need good bottom-up data to match what we’re measuring looking down from space. That’s what we need to really advance greenhouse gas policies.”

See:

“2018 Progress Report: California’s Sustainable Communities and Climate Protection Act,” California Air Resources Board, November 2018

“Regions across California likely off the hook for 2020 caps on greenhouse-gas emissions from driving,” Joshua Emerson Smith, The San Diego Union-Tribune, 27 November 2018

“Poor forest management: Trump oversimplifies state’s fire problem,” Readers React, The San Diego Union-Tribune, 20 November 2018

“A Fine-Tuned Map for CO2,” Barbara Moran, Boston University Research, 26 October 2017

“A New Map for Greenhouse Gas,” Barbara Moran, Boston University Research, 10 April 2015

Gately, Conor, K.; Hutyra, Lucy, R.; Sue Wing, Ian, 2015, “Cities, traffic, and CO2: A multi-decadal assessment of trends, drivers, and scaling relationships“, https://doi.org/10.7910/DVN/28999, Harvard Dataverse, V6