Marin's climate action plan to stress benefits of carbon farming


In its quest to meet California’s goal of bringing greenhouse gas emissions to 40 percent below 1990 levels by 2030, Marin considers its farmers and ranchers a key part of the solution. 

“There’s not another sector in which there’s potential to actually draw down emissions like there is in agriculture and working lands,” Alice Zanmiller, a planner with the Community Development Agency, said during a recent presentation to members of the Marin Conservation League. “The county is excited about all of the potential in the sector, both to improve ecological services but also to actively sequester carbon.”

A strategy for expanding carbon farming practices in Marin will be included in a renewed climate action plan that will outline emission reduction strategies for unincorporated areas. The county plan, an update from a 2015 version, is expected to be released this fall and brought to the supervisors by the end of the year.

On the one hand, agriculture is the largest source of emissions in the unincorporated area of Marin, just ahead of transportation and energy use. The sector accounts for about a third of unincorporated Marin’s emissions, generating the equivalent of 115,000 metric tons of carbon dioxide a year. For the county as a whole, agriculture produces just 8 percent of emissions.

The climate plan will provide measures to reduce emissions produced on farms, and outline ways to expand upon the practices that already have been shown to sequester carbon. The county has solicited help from leading groups in the field—the University of California Cooperative Extension in Marin, the Marin Resource Conservation District, the Marin Agricultural Land Trust and the Carbon Cycle Institute—that partner in the Marin Carbon Project.

When the plan’s previous iteration was developed, the Marin Carbon Project was in its early days and did not yet have extensive data on the benefits of carbon farming. The current climate plan, which is on track to reduce emissions by 30 percent from 1990 levels by the end of 2020, condones carbon farming generally but does not prescribe it or delve into the specifics.

The county partners are now working to evaluate the carbon sequestration that has been documented in Marin to date, to determine how much farmland remains that could benefit from carbon farming, and to calculate how much carbon could be sequestered overall in Marin. The team is still making calculations, but offered a sneak preview during a meeting of the conservation league’s agriculture and land use committee in July.

Nancy Scolari, the executive director of the Marin Resource Conservation District, said her group to date has helped create 19 carbon farming plans for over 8,000 acres of farmland. Once those plans are fully implemented, the farms will together sequester the equivalent of 11,585 metric tons of carbon dioxide per year. For perspective, a typical passenger vehicle emits 4.6 metric tons of carbon dioxide every year, so the farms are on track to offset the emissions of more than 2,500 cars.

Data from the existing carbon farm plans, the first of which were implemented in West Marin in 2013, show the particular benefits of each type of practice, such as compost application, tree and shrub establishment, windbreaks, conservation cover and riparian restoration. The local groups are using geographic information system mapping to determine how much potential there is in Marin today for each of these practices.

Dr. Jonathan Wachter, a soil scientist for the Marin Agricultural Land Trust, said his preliminary analysis showed that utilizing available lands for compost application alone could sequester 104,069 metric tons of carbon dioxide each year. That by itself would balance out the contribution that agriculture makes to emissions in Marin.

Dr. Jeff Creque, the director of the Carbon Cycle Institute, said that implementing several alternative manure management scenarios—methane digesters, dry scape systems and a variety of composting methods—in combination with the other land management practices offers the potential for ranches and dairies to become carbon neutral or even carbon negative.

Interest for this type of work from farmers and ranchers runs strong. There are more than 20 other producers in line for assistance in creating a carbon farm plan, and an additional 60 who have expressed interest in implementing carbon sequestration practices. Yet Ms. Scolari said the groups were unable to scale up due to resource limitations—something she hoped the county could help with.

Ranchers who lease lands from the National Park Service, who account for around 20 percent of the total agricultural production in Marin, have been prevented from developing carbon farm plans, despite their interest in doing so. The amendment to the Point Reyes National Seashore’s general management plan, which is expected to soon be finalized, may clarify the park’s position on the plans.

Still, individual carbon sequestration practices have been implemented on seashore ranches as part of other conservation efforts. Demonstrating the potential for increased collaboration, Ms. Scolari said the park service also has plans to fund a new position under her organization to support stewardship activities within the seashore.