California must retire existing heavy-duty trucks to meet the state’s 2045 carbon neutrality goals, in addition to promoting the purchase of zero-emissions vehicles (ZEVs), a new study has found.
Stricter policies that cover both the rollout of zero-emissions trucks and the early retirement of gas-guzzlers could slash cumulative greenhouse gas emissions by 64 percent, according to the study, published on Monday in Environmental Research: Infrastructure and Sustainability.
Such a move could also reduce half of the state’s pollution-related mortality, particularly within disadvantaged communities, the study authors determined.
As the world’s fifth-largest economy, California produces about 0.75 percent of global greenhouse gas emissions, the researchers noted.
Heavy-duty vehicles alone contribute about 8 percent of the state’s total emissions — generating about 32 million tons of carbon dioxide annually, or about the same amount that New Zealand produces each year.
“While ZEV sales mandates are effective, it is clear from our analysis that they will not be sufficient for reaching zero emissions on the desired timescales,” lead author Eleanor Hennessy, a postdoctoral scholar at Arizona State University, said in a statement.
“Accelerated retirement programs will be critical for California to reach emissions targets by 2045,” Hennessy added.
To draw this conclusion, the researchers modeled the effects of two proposals aimed at curbing emissions from heavy-duty vehicles. The first would only require the sale of ZEVs by a set date, while the second focused on the early retirement of existing combustion engine trucks.
The model evaluated the simultaneous potential of these two policies on various implementation dates, while incorporating data from the California Air Resources Board’s fleet emissions database as well as pollution expected from increased electricity production.
Also assessing the potential health impacts linked to the continued operation or removal of combustion-engine vehicles, the authors found that a business-as-usual scenario would yield 8,000 excess deaths between 2019 and 2045.
Even with highly aggressive ZEV sales mandates, the authors found that instituting such requirements alone would leave 17 percent of today’s internal combustion engine stock and 8 percent of annual carbon emissions intact in 2045.
Instituting decarbonization policies that combine both ZEV adoption and long-haul, heavy-duty truck retirement would generate widespread benefits and enable the state to meet its long-term climate targets, according to the study.
Such a shift would bring the biggest air quality improvements to Black, Latino and low-income communities, where residents have disproportionately been affected by such emissions and related health issues, the study found.
The authors acknowledged that the removal of heavy-duty vehicles “comes at a cost,” as the owners would likely require compensation from the state to prevent resales outside of California.
They therefore recommended that state officials prioritize the elimination of vehicles whose removal would be most cost-effective.
“Early retirement of long-haul heavy heavy-duty trucks, and heavy heavy-duty trucks operating in ports would have the greatest net benefit, along with the largest magnitude of reduced climate and health damages,” they concluded.