Organic Materials Management and Climate Change

California disposed approximately 39 million tons of waste in landfills in 2018, of which approximately one third is compostable organic materials, including 18 percent food, 12 percent lumber, 9 percent landscape waste, and nearly 20 percent paper and cardboard. (See the Executive Summary from the 2014 Waste Characterization StudyPDF download).

Inedible food waste can be composted or used to generate renewable energy; landscape waste is ideal for composting; and lumber can be turned into mulch, used in a biofilter, or burned in a biomass plant for renewable energy.  Paper can be composted, but greater climate benefits are achieved when it is recycled, allowing other trees to stay in the ground.

Anaerobic decomposition of organic materials in landfills produces methane (CH4), a greenhouse gas with global warming potential approximately 85 times higher than carbon dioxide (CO2) over a 20-year time period. Landfills emit the majority of man-made methane emissions in California, and are one of the top emitters in the United States. Reducing the amount of organic materials sent to landfills and increasing the production of compost and mulch are part of the AB 32 Scoping Plan.

Legislation passed over the last few years has reinforced CalRecycle’s commitment to protecting the climate by reducing landfill disposal of organic materials, and repurposing those materials to feed food-insecure people, make carbon sequestering fertilizers and soil amendments, and generate clean, low-carbon renewable energy. Chief among these are:

SB 1383 (Lara, Chapter 395, Statutes of 2016) targets a 50 percent reduction of statewide organic waste disposal from the 2014 level by 2020, and a 75 percent reduction by 2025. Grants CalRecycle regulatory authority to achieve the organic waste disposal reduction targets and establishes an additional target that not less than 20 percent of currently disposed edible food is recovered for human consumption by 2025.  Attaining this goal will require an expansion of California’s organics infrastructure, creating infrastructure, jobs and value-added products along the way. Find out more about SB 1383 and regulatory development.

AB 1826 (Chesbro, Chapter 727, Statutes of 2014) requires businesses to recycle their organic waste, depending on the amount of waste they generate per week. Cities and counties across the state must implement an organic waste recycling program to divert organic waste generated by businesses, including multifamily residential dwellings that consist of five or more units. Find out more about Mandatory Commercial Organics Recycling.

AB 1594 (Chesbro, Williams, Chapter 719, Statutes of 2014) Green materials are the perfect feedstock for composting, but are sometimes used to cover garbage in landfills at the end of the day, a practice known as alternative daily cover (ADC).  Green materials used for daily cover break down anaerobically in a landfill, the same as if they were disposed.  AB 1594 eliminates incentives to use green materials as ADC by ensuring it counts as disposal. Find out more about green material as landfill daily cover.

AB 341 (Chesbro, Chapter 476, Statutes of 2011) set a goal of a 75 percent reduction in the amount of waste going to landfills by the year 2020, to be achieved through source reduction, recycling, and composting.


To meet the goals of SB 1383, it is estimated that California will need to double the size of the current organics materials management infrastructure. CalRecycle has identified barriers and corresponding solutions to help facilitate the construction and safe operation of this next-generation infrastructure:

CalRecycle Organics Grants: Provide funding for selected projects that compost or digest previously landfilled organic materials and turn them into compost, soil amendments, fertilizers, and renewable electricity or biogas.

SB 1383 Infrastructure and Market Analysis Report: This 2019 report estimates the current capacity of the state’s organics infrastructure and analyzes the types of products made and the markets for those products.

Statewide Benefits of CalRecycle’s Organic Waste Reduction Strategy: A one-page fact sheet that outlines the benefits of reducing landfilling of organics.

Scientific Research and Technology Evaluation

CalRecycle funds and supports research to answer important scientific questions and to ensure program initiatives are based on the best available science. CalRecycle collaborates with other agencies to ensure shared research priorities receive prompt attention.

  • Compost-Greenhouse Gas Research. CalRecycle funded research by UC Davis to estimate the greenhouse gas impacts of compost production and use. The project included field research to measure the impact of compost application on N2O emissions from intensively farmed lands—one of the largest N2O sources in California—as well as laboratory incubations checking the impact of compost on soil CH4 and N2O emissions for multiple soil types and different chemical fertilizer applications.
  • Compost as a Landfill Cover. CalRecycle studied the feasibility of placing a biocover of compost over the surface of a landfill to control escaping methane.

Markets: Improve Economic Incentives for Organics Diversion and Markets for finished compost products

Composting and anaerobic digestion compete with low-cost landfilling and direct land application for feedstocks, reducing operators’ ability to pay for infrastructure development, product marketing, and other essentials. CalRecycle works to find ways to monetize the inherent value of advanced organics handling facilities.

  • Healthy Soils Initiative and Climate Adaptation: CalRecycle worked with the California Department of Food and Agriculture to develop the Healthy Soils Program, a program which helps farmers and ranchers defray the cost of initiatives which lead to carbon sequestration, improved habitat, and healthier soils. The Healthy Soil Initiative will pay for compost application, mulch application, and dozens of other practices proven to sequester carbon. Thanks to pioneering research by the Marin Carbon Project, compost use to increase rangeland productivity is gaining traction. The Natural Resources Agency’s Draft 2030 Natural and Working Lands Climate Change Implementation Plan proposes compost use on thousands of acres of California lands to improve soils, sequester carbon, and increase net primary productivity.
  • Help Caltrans develop compost specifications and best management practices: California has thousands of miles of state highways, and hundreds of thousands of miles of locally maintained roads. Increasing the use of compost along roads can help establish plants and reduce erosion after construction or rehabilitation, and can reduce the need for and the cost of irrigating highway vegetation. Recent legislation requires CalRecycle to work with each Caltrans district to help ensure compost and mulch made from recycled organic materials is used whenever and wherever it is appropriate.  SB 1383 regulations will require cities and counties to use more organics in their construction projects and in their regular maintenance of public facilities and rights of way.
  • Compost use on fire-scarred lands: Recent legislation requires CalRecycle to increase the use of compost for revegetation and slope stabilization on lands impacted by fire. CalRecycle is a key partner in multi-agency efforts to efficiently remove ash, toxic waste, and debris following major wildfires. Hundreds of thousands of linear feet of compost filter socks are currently being deployed for erosion control purposes during CalRecycle’s cleanup of the Camp Fire.
  • Climate-Appropriate Landscaping: CalRecycle is ready to work with all stakeholders to ensure that the benefits of climate-appropriate landscaping—including reduced water use, reduced waste to landfills, carbon sequestration in the soil and in plants, and a healthier environment—are realized.
  • Compost and mulch for erosion control: Many climate models forecast less snow, more high-volume rain events, and more frequent high wind events, increasing the chance for devastating erosion and mudslides. CalRecycle works with stakeholders to increase compost and mulch use for erosion control. This includes collaborating with Caltrans on compost and mulch specifications in which erosion control is the primary goal and with the Department of Water Resources on the Model Water Efficient Landscape Ordinance (MWELO) in which erosion control is a secondary benefit resulting from water efficient landscape design.
  • Low Carbon Fuel Standard (LCFS): The LCFS program’s goal is to reduce the carbon intensity of transportation fuels 20 percent by 2030. Low carbon fuel producers can apply to the program and obtain LCFS Credits transferable at a LCFS market price. The California Air Resources Board has developed a Simplified Carbon Intensity (CI) Calculator for Biomethane from Anaerobic Digestion of Organic Waste for projects producing renewable fuels via anaerobic digestion to determine the fuel’s greenhouse gas reduction per unit energy (gCO2e/MJ).

For more information contact: Climate Change,