California Air Resources Board

Mighty Earth is a non-profit dedicated to protecting the climate and nature. Visit www.mightyearth.org to learn more about our mission and programs. Below is Mighty Earth’s response to the solicitation of public comments for the implementation of SB 1383.

Question #1.
Dairy and beef livestock operations should be required to publicly report their emissions of methane and other greenhouse gases in native units, as outlined by the Greenhouse Gas Protocol methodology, rather than solely as CO2e, which can mask the short-term impacts of methane emissions. Dairy and livestock operations should also be required to report herd and slaughter numbers on a monthly or quarterly basis, to increase transparency and third-party verification of methane emissions.

Question #14.
CARB should prioritize paying farmers to reduce their herd sizes. According to an analysis by Friends of the Earth (2024) “If the government paid producers to reduce their herd sizes through a per-cow payout equal to the average net revenue per cow over the last ~20 years, the cost of mitigating one metric ton of CO2 e would be less than $10 total... Paying farmers to reduce herd sizes or transition to another type of farming would also make dairy farming more profitable for the farmers who remain in the sector, because profits are currently suppressed by low prices driven by an oversupply relative to demand.”

These numbers suggest that paying farmers to reduce their herd sizes is more cost-efficient than spending money to build anaerobic digesters. Between 2015 and 2022, the state of California spent around $200 million to expand the use of anaerobic digesters on dairy farms. An analysis of anaerobic digesters in California by the Center for Food Safety found that, with all public funding and market incentives considered, the cost of abating one ton of CO2e via anaerobic digester is much higher than the state’s estimated $9 --- it may be closer to $159 per ton. Additionally, anaerobic digesters raise a variety of concerns, including unaccounted for methane leaks, increased ammonia pollution, and the incentive for farms to consolidate. Reducing herd sizes raises none of these concerns.

We also recommend implementing agroecological practices on farms; practices that recover degraded pasture can increase feed quality, which has been shown to methane emissions through a reduction of methanotrophic bacteria in pastures and increased efficiency of rumen methane emissions.

Sources:

Analysis by the Center for Food Safety covered in Agriculture Dive, 2025: https://www.agriculturedive.com/news/center-for-food-safety-california-…

Analysis by Friends of the Earth, 2024: https://foe.org/wp-content/uploads/2024/03/Factory-Farm-Gas-Brief_final…

Strategies to Mitigate Enteric Methane Emissions from Ruminant Animals (2022): https://pmc.ncbi.nlm.nih.gov/articles/PMC9628856/

Question #21.
The key objective should be to regulate livestock and dairy in order to support practices that reduce absolute methane emissions. In order to achieve this objective, CARB should consider the macro-economic impacts of its programs. For example, providing an additional income stream for dairy operations by subsidizing anaerobic digesters may eventually result in increased herd sizes to capitalize on the production of renewable natural gas – especially as the price of natural gas increases due to external market forces. Increased herd sizes, and therefore more methane emissions via enteric fermentation, may negate any methane reductions from manure methane capture.

CARB should also consider objectives to reduce other environmental impacts of dairy farming, such as water pollution, water use, and air pollution (such as ozone, ammonia and nitric oxide). CARB should also consider an objective to implement programs equitably amongst small and large dairy operations, so as not to incentivize further consolidation in the industry.

Question # 23
CARB should prioritize metrics that reflect absolute methane reductions at the facility level, rather than relying primarily on intensity-based metrics. Intensity metrics can obscure rising total emissions associated with herd expansion, for example.