According to a recently published study on the energy and emission of cannabis production, greenhouse gas emissions in the legal marijuana sector have increased so rapidly over the past few years that they are now equivalent to that of approximately 10 million vehicles. However, switching from indoor to outdoors grows could reduce this environmental impact up to 76 percent.
Evan Mills is a researcher based in Northern California who spent many years developing a model that accounted for the energy inputs of and outputs from the legal cannabis sector. In total, his paper published in One Earth concludes the energy consumption of this sector “is on par with all other crop-production” and the marijuana industry accounts for 1 percent of national “total emissions of all sectors.”
According to the report, “the cannabis industry uses fuels and electric power on site at a rate four times higher than the US pharmaceutical and tobacco industries, and the beverage industry.”
The report adds that “energy use in data centres is about a third less than what’s used nationally, and 1.5 times more energy is consumed by cryptocurrency mining.”
Mills’ lifecycle analysis does not only include the cultivation process, but also transport, retail, and waste disposal.
“Cannabis has become the most energy- and carbon-intensive crop,” the author wrote, “as cultivation has shifted from open fields to indoors, covering an area of ∼5 million square meters (∼270 average Walmart stores) in the US.”
He noted that the physical footprint of artificially-lit food production in Canada and floriculture is larger.
Evan Mills / One Earth
However, not all cannabis is created equal in energy and emission use. Mills’s report states that 90 percent of cannabis-related emissions are from indoor cultivation, which is far more energy intensive.
The indoor cultivation of crops can have negative effects on the air quality in and outside, electricity grids, waste, water consumption, energy costs and worker safety.
As far as reforms go, the new paper says federal legalization of marijuana “would achieve only modest reductions” in energy and emissions—about 8 percent overall—though it notes a national-level reform “could enable more potent policies.”
It is best to move away from indoor cultivation and towards outdoor cultivating.
The report states that “Emissions are up substantially, despite state-level efforts to legalize marijuana. This suggests that depending on the market alone as a climate strategy is not viable for this industry.” To manage emissions more targeted policy initiatives will be needed. And the best way to do this is by guiding the cannabis industry in the direction of a greater share of open field cultivation.
Additional policies that reduce emissions could include increasing homegrown cannabis cultivation, using greenhouses more widely by cultivators and adopting energy-efficient varieties of plants, as well as implementing on-site Solar.
In the legalization of cannabis, there is also an increased risk for emissions. If, for instance, marijuana were to be grown more indoors or delivered more directly to customers’ doorsteps, the emissions under this model would go up.
According to the study, if 50% of all sales took place through deliveries, this would result in an increase of emissions by 4%. The study says that if one quarter of outdoor cannabis was moved inside, this would increase emissions by 10 percent.
The report states that “key upward pressures” include the rising demand for marijuana, the changes to industry structure, the reversion by legal producers of the illicit market, where electricity can be less clean and more inefficient, in response to perceived overzealous regulation, and the trend towards derivative products with added processing energy.
Evan Mills / One Earth
Mills stated that although consumers can access information on energy usage for other products, this information is not usually available in the case of cannabis.
He told The Washington Post that “consumers are unaware of any of these things.” The Washington Post reported that “consumers don’t even know what this is.”
The new analysis does not take into account interstate commerce. This could be approved as a part of the federal legalization process or separately. This would enable regions that are better equipped to cultivate cannabis outdoors to do so and then sell the product elsewhere.
Mills’s model for federal legalization does not explore this dynamic. “The ‘full legalization’ case,” his paper says, “does not model the possible effects of relaxing restrictions on interstate commerce or other policies that could be deployed in a legal market.”
Nevertheless, it continues, “In the event that interstate transport bans were lifted, related questions would be whether states with climates that do not favor open-field cultivation…would opt instead to import from states where it is more feasible (and where indoor cultivation is also less energy intensive).”
The paper notes that the current trend in cultivation is the wrong one. The paper notes that “large-scale indoor cultivation” is becoming more concentrated in urban areas with a high environmental burden, as seen in Oakland, Denver and other cities which each host around 200 plant factories.
A separate study conducted last year found that outdoor cannabis cultivation can produce up to 50 percent less greenhouse gases than indoor production.
In a report that was published in the Journal of Agricultural Science and Technology by the authors, they noted that although a small number of studies examined indoor cannabis production, there is “little information available about the impacts of outdoor marijuana agriculture.”
They wrote: “This knowledge should be widely disseminated to producers, consumers and officials of nations who have legalized cannabis or are planning on legalizing it.”
Some bodies are stepping up their efforts to reduce the impact of cannabis cultivation, despite the fact that the environment impacts of the production of the drug is often ignored by consumers, policymakers and the industry.
Colorado launched an energy efficiency program in 2023. This was based on a state energy report that found cannabis cultivation to be 2 percent of total energy usage. According to the report, electricity costs growers a lot too. It eats up about a third their budgets.
In 2020, Colorado launched a more experimental program aimed at using cannabis cultivation to capture carbon from another regulated industry: alcohol. Carbon Dioxide Reuse Pilot Project was a state-funded program that captured carbon dioxide released during the brewing of beer and then used it to promote marijuana growth.
In a 2023 report, the International Coalition on Drug Policy Reform and Environmental Justice drew the attention of the public to the adverse effects of the unregulated production of drugs in places like the Amazon Rainforest and Southeast Asia’s jungles.
Attempts to protect those critical ecosystems, the report warned, “will fail as long as those committed to environmental protection neglect to recognize, and grapple with, the elephant in the room”—namely “the global system of criminalized drug prohibition, popularly known as the ‘war on drugs.'”
The Biden administration was urged to investigate the effects of marijuana production on the environment by a couple of U.S. congressional members who opposed legalization. In stating their reservations, they wrote, “We have concerns about the subsequent emissions of marijuana farming and we believe that more research on this industry is required, including its rapidly expanding demands on energy systems in our country, as well the impact on our environmental.”
Jared Huffman said, in a MEDCAN24 interview conducted at the time by a legalization advocate Rep. Jared Huffman of California (D-CA), that there are “some important nuances” to consider when it came to the cannabis environment and policy.
Illicit growers are diverting water resources that could be used by the industry and community in California despite extreme drought conditions.
“We have not done a very good job of lifting up the legal market so that we can eliminate the black market—and that black market has really unacceptable environmental impacts,” he said at the time.
California itself has taken some specific steps to ameliorate the issue. Officials announced, in 2021, that they would be soliciting concepts for a marijuana-tax-funded program to help small cannabis producers with environmental cleaning and restoration.
The following year, California awarded $1.7 in grant money to sustainable cannabis growers, part of a planned $6 million in total funding.
And in New York, set rules meant to promote environmental awareness, for example by requiring businesses to submit an environmental sustainability program and explore the possibility of reusing cannabis packaging. Lawmakers there also explored promoting industry recycling programs and cannabis packaging made from hemp rather than synthetic plastics, though neither proposal was enacted.
‘Outdated’ Marijuana Packaging Rules Make It ‘Impossible’ For Cannabis Industry To Be Environmentally Sustainable, Study Says
Side Pocket Images. Image courtesy Chris Wallis.
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