In a new study in the journal BioScience, a team of researchers including Stanford professor Roz Naylor links marijuana cultivation to widespread environmental damage in California and calls for greater regulation of the crop’s impact on natural ecosystems.

Recent debates about marijuana legalization have focused on the potential social, health and economic impacts, with little attention paid to environmental issues. The new study, spearheaded by the California chapter of The Nature Conservancy, brings environmental concerns to the forefront of the policy discussion. Between 60 and 70 percent of the marijuana consumed in the United States comes from California.
 

Water and wildlife

Marijuana plants require nearly twice as much water as do grapes or tomatoes, and the last five years have brought a 50 to 100 percent increase in the amount of northern California watershed lands used for marijuana production – figures that are causing growing concern among conservationists in the midst of a severe statewide drought.

The majority of California agriculture is subject to heavy water use regulations. Farmers of most irrigated crops help their plants through the dry summer months by filling water tanks in the winter, when streams and springs are full.

By contrast, many marijuana growers draw surface water during the plant’s summer growing season, when drought conditions are worst.

“Taking water directly from rivers and streams in the summer not only reduces the water available for agriculture but also threatens wildlife species, especially birds and fish, that depend on these wetland ecosystems for survival,” said Naylor.

Illegal marijuana plantations in California are associated with a wide range of other environmental impacts, including pollution, poaching, and pesticides that poison wildlife. Even legal outdoor cultivation can cause deforestation and soil erosion.
 

Policy options

The research team identified several opportunities to reduce the environmental impacts of marijuana cultivation in California. For example, states can:

• Offer incentives for growers to protect natural resources
• Enforce new or existing environmental laws,
• Use sales tax revenues to fund restoration projects
• Implement certification or labeling programs to encourage consumers to buy sustainably grown products.

“Regardless of the legal status of marijuana, the way we are currently managing its impacts on water and wildlife in California just doesn’t work,” said Naylor. “Bringing these impacts into future policy discussions about marijuana is critical for protecting California’s environmental resources given the high value and demand for the crop.”

Naylor is William Wrigley Professor of Earth Science at Stanford, director of the Center on Food Security and the Environment, and a senior fellow at the Stanford Woods Institute for the Environment and the Freeman Spogli Institute for International Studies. She serves as a trustee of The Nature Conservancy California Chapter.

Media Contact

Laura Seaman, Communications Manager, Center on Food Security and the Environment: lseaman@stanford.edu 
Lisa Park, Media Relations, The Nature Conservancy: lpark@tnc.org.

A research team led by FSE director Rosamond Naylor has won a $400,000 multi-year grant to study how to create sustainable palm oil supply chains that promote economic growth and environmental sustainability in Indonesia and West Africa. 

Palm oil has become one of the world’s fastest growing and most valuable agricultural commodities. Global production of palm oil doubled in both volume and area each decade between 1970 and 2010, and is expected to double again by 2025. The windfall profits from this rapid expansion have come at a cost of tropical deforestation, biodiversity loss and rising greenhouse gas emissions, and in many cases the economic benefits have bypassed local smallholder farmers. 

Naylor and her team of Stanford faculty, scholars and students will undertake the three-year project with funding from the Stanford Global Development and Poverty Initiative (GDP), launched in Spring 2014. GDP aims to transform Stanford’s capacity to speak to the challenges of poverty and development. This year, GDP awarded more than $2 million to 13 faculty research teams from across the university. 

The new project marks the first venture that connects Stanford’s expertise in sustainability with the Graduate School of Business’ experience in value chain innovations. The team will conduct an evaluation of value chain opportunities for sustainable palm oil production, build corporate partnerships to improve smallholder incomes, and engage in policy advising. 

GDP is a joint initiative of the Stanford Institute for Innovation in Developing Economies (SEED) and the Freeman Spogli Institute for International Studies (FSI). SEED is housed within the Stanford Graduate School of Business. 

Rosamond Naylor is William Wrigley Professor of Earth System Science and Senior Fellow at the Stanford Woods Institute for the Environment and at FSI.

FSE director Roz Naylor has been selected to deliver the 6th annual Ned Ames Honorary Lecture at the Cary Institute of Ecosystem Studies in Millbrook, NY on Friday, April 24. Her lecture on "Feeding the World in the 21st Century," is free and open to the public, and a video recording of the event will be available on the Cary Institute's website shortly after the talk.