The vilified nut has a surprisingly small carbon footprint.

Almonds, vilified during the current drought for being one of California’s thirstier crops, have a surprisingly small carbon footprint compared to other nutrient-rich crops, reports a team of researchers at the University of California, Davis, and UC Agriculture and Natural Resources.

The findings are important for evaluating the environmental impact of California-grown almonds, which make up 80 percent of the world's commercial almonds. The term “carbon footprint” refers to the total amount of carbon dioxide and other greenhouse gasses produced annually by an activity or entity and is of concern because of the impact greenhouse gases have on global warming.

"Our research shows that 1 kilogram of California almonds typically produces less than 1 kilogram of CO2-equivqlent emissions," said Alissa Kendall, an associate professor in the UC Davis Department of Civil and Environmental Engineering and corresponding author on two related open-access papers published this week in the Journal of Industrial Ecology.

Kendall noted that the study results include the use of almond co-products — orchard biomass, hulls and shells — for renewable power generation and dairy feed. Orchard biomass refers to prunings as well as trees removed from an orchard.

“Under ideal circumstances, which are feasible but not in place today, California almonds could become carbon-neutral or even carbon-negative, largely through the improved utilization of orchard biomass,” Kendall said.

An activity or process is considered carbon-negative if, overall, it leads to a net reduction of greenhouse gases, either by directly removing and sequestering CO2 from the atmosphere or by avoiding greenhouse gas emissions that would otherwise occur.

“Only a full, life cycle-based model like the one we developed for this research will allow us to accurately assess whether incorporating the biomass into the soil or using it for power generation instead results in a lower net carbon footprint,” said co-author Sonja Brodt, academic coordinator in the UC ANR Sustainable Agriculture Research and Education Program at UC Davis, noting that there will be some trade-offs.

Almond demand spurs plantings

Popularity of almonds and almond-based products has spurred California almond acreage to expand from 510,000 acres in 2000 to roughly 890,000 acres in 2015, according to the USDA National Agricultural Statistics Service.

The new UC study reported in these articles was prompted by growing interest among consumers and food companies in the carbon footprint of various food products and by California’s Global Warming Solutions Act of 2006, which requires statewide reductions in greenhouse gas emissions.

Study collaborators and funding

The first article, "Life Cycle-based Assessment of Energy Use and Greenhouse Gas Emissions in Almond Production, Part I: Analytical Framework and Baseline Results," is authored by Kendall; Elias Marvinney, a graduate student in the UC Davis Department of Plant Sciences; Brodt; and Weiyuan Zhu, a UC Davis graduate student in horticulture and agronomy.

Marvinney is lead author of the second article, "Life Cycle-based Assessment of Energy Use and Greenhouse Gas Emissions in Almond Production, Part II: Uncertainty Analysis through Sensitivity Analysis and Scenario Testing," in collaboration with Kendall and Brodt.

Funding for the study was provided by the Almond Board of California and the California Department of Agriculture Specialty Crop Block Grant Program.

Additional information:

• Related: Devastating citrus greening disease targeted by USDA grants
• Related: Science casts light on sex in the orchard
• Related: New findings on beetle flight may help control deadly walnut tree disease