The huge carbon output of modern cannabis production is no secret. According to Colorado’s Department of Public Health and Environment, 1.3 percent of the state’s total annual carbon emissions stem solely from cannabis. A rigorously researched and widely publicized 2021 article in Nature Sustainability found that indoor production, the dominant form in many areas, generates “2,283 to 5,184 kg CO2-equivalent per kg of dried flower.” This staggering carbon output comes mostly from the voracious energy demands of indoor cultivation. Rather than relying on the sun for photosynthesis, artificial illumination is necessary; rather than relying on the wind for ventilation, industrial-scale fans must be used. Dehumidification is also needed, as is cooling during warm periods. In Southern California’s scorching Coachella Valley, the state’s emerging center of corporate cultivation, air-conditioning expenditures can be astronomical. Here even the local water supply requires energy-intensive purification. And, as if to add insult to injury, carbon dioxide is intentionally released into growing facilities to enhance production, some of which inevitably escapes into the atmosphere.
Bizarrely, large cannabis corporations and their cheerleaders sometimes brag about their energy use. Consider, for example, this 2016 article from the Coachella Valley Weekly entitled, “Canndescent: Setting the Bar for Cannabis Cultivation in Desert Hot Springs”:
Impressive at every turn, Sedlin gave a tour describing how the Canndescent facility intends to grow, clone and package premium weed.
He proudly, and probably with more detailed information than necessary, showed how the plants require the perfect temperature, water and light for maximum growth.
The facility is equipped with a 160-ton air conditioner. DHS [Desert Hot Springs] water, known for its award-winning minerals and taste, is not however good for cannabis, so Canndesecent has to use a reverse osmosis system with a 5,000 gallon water backup supply. Plant fertilization is electronically distributed. A shiny outdoor tank containing 1,000 gallons of liquid CO2 pumps the right mixture into sealed rooms producing the ideal growing environment. …
Canndescents’ grow rooms look like something on a Mars’ space station. Everything appears sterile, bright, well-organized and utilizes every inch of space with custom, stainless steel, movable grow beds. Hi-tech monitors are taking constant readings of the air quality. Fans insure the air is moving evenly.
When confronted with this outsized carbon footprint, indoor cannabis apologists typically point to their solar cells, arguing that they are doing their part to reduce their impact. This is simple greenwashing. Solar cells provide “clean” energy only in a relative sense, insofar as they substitute for fossil fuels. If they are used instead to replace sunlight, they are anything but green. Few indoor facilities, moreover, have enough solar cells and battery banks to provide all their energy needs.
In California, indoor cultivation accounts for only around thirty percent of cannabis production, less than in most states with a legal market. But outdoor growing, known in the business as “full sun,” accounts for an even lower share (see the graph posted below). Most California cannabis is grown in greenhouses under “mixed light” conditions. Here most of the energy needed for photosynthesis does come from the sun, but supplementary artificial lighting is used as well. Power-hungry ventilation is also necessary, as are other energy expenditures unknown in outdoor growing. In the final tally, mixed light is far less carbon intensive than indoor cultivation – but far more carbon intensive than outdoor growing.
There are several reasons why indoor and greenhouse production predominate. Outside of California and a few neighboring areas that have a Mediterranean climate, high-quality cannabis cannot be easily grown in the open air. Low humidity is necessary during the crucial late summer and early fall flowering period; otherwise, the flowers will be attacked by mold. Dry weather through September and October, however, is uncommon over most of the country. As federal anti-cannabis laws prevent interstate commerce, each state must produce its own crop, requiring in most cases enclosed growing environments and extensive dehumidification. Under a rational, environmentally sound cannabis regime, most production would take place in California and neighboring states; a state like New York would no more use massive, artificially illuminated buildings for cannabis production than it would for lemons or artichokes.
The triumph of high-carbon cannabis in California stems from both market pressure and government policies. When large-scale corporate cannabis began to flood the market a few years ago, artisanal cultivators came under increasing stress. To remain competitive, many took up mixed-light production themselves, as it allows multiple harvests per year and thus helped maintain profits as the wholesale price started to drop. More insidious are the pressures imposed by consumers in the retail marketplace. Most self-styled connoisseurs prefer indoor flowers, as they tend to be more uniform, visually appealing, and potent than those grown in the sun. As a result, indoor growers enjoy a pronounced price advantage, easily making up for their additional energy costs. The root problem here is the adolescent nature of the core cannabis market, where raw potency reigns supreme, while social, environmental, and cultural considerations, as well as flavor, are usually ignored. If alcohol operated under the same market constraints, fine wine and artisanal beer would be marginalized long ago by 190-proof Everclear.
But the more fundamental reason for the collapse of low-carbon cannabis in California is government policies that discourage and sometimes even prevent full-sun cultivation, while favoring indoor and mixed-light production. Many of these policies are covert, as they are ostensibly aimed at other issues. Some, however, are straightforward. As a recent MJBizDaily article notes:
Onerous regulations or outright bans on outdoor cultivation sites by many California counties also have made it harder for outdoor grow operations to expand their footprints.
Of the 26 counties in the state that have issued cultivation licenses to date, 14 haven’t awarded any to outdoor growers.
To say that California’s cannabis policies are hypocritical is an understatement of the first order, as will be explored in the final post in this series. But first we need to consider one more issue: the carbon footprint of full-sun cultivation. Although very low by comparative measures, it is not negligible. Some growers, however, do everything they can to minimize their emissions, and a few might even achieve carbon neutrality and perhaps even negativity. Yet for all their efforts, they receive little if any credit, whether in the market, from regulators, or from environmental organizations.