Legalized marijuana is a global warming nightmare

Legalized marijuana is a global warming nightmare

by Christine L. Miller

 | August 05, 2022

Leaders in the Democratic Party are backing legislation to reduce carbon emissions. Some of them are also sponsoring bills that would expand the cannabis industry, ranging from the MORE Act to the Safe Banking Act and now the Cannabis Administration and Opportunity Act just introduced by Senate Majority Leader Chuck Schumer (D-NY). Co-sponsors have publicly chastised President Joe Biden for not doing enough to help in their effort.

They are seemingly unaware that although today’s cannabis may seem “green” — after all, it traps carbon dioxide in organic material and generates oxygen in the process — its similarity to other green plants ends there. Commercial cannabis is primarily grown indoors, where the electricity required for grow lamps and temperature and humidity control generates a massive net carbon footprint.

In 2012, Evan Mills, a staff scientist with Lawrence Livermore National Laboratory, was surprised to find an abundant stock of high-intensity grow lights and inquired what they were used for. The answer led him to a climate change time bomb that would eventually portend serious problems for our environment. His analysis at the time showed that for every kilogram of cannabis flower sold, 4,600 kilograms of carbon dioxide were produced. This is orders of magnitude greater than the ratio for food products and also substantially higher than other non-nutritive substances marketed for our consuming pleasure, including wine, beer, tobacco, and coffee.

Other studies on the problem followed, culminating in a 2021 publication by researchers affiliated with Colorado State University. Hailey Summers and colleagues corroborated Mills’s perspective, finding that the cannabis industry in Colorado alone generates the carbon equivalent of 520,000 additional gasoline-powered vehicles on the road based on the average EPA estimate for fuel efficiency for 2018. Power companies have long been aware of these large energy requirements, in part because unusual spikes in their grid frequently lead to the discovery of illegal growers who tap electrical lines.

Energy-efficient lighting is already incorporated into the industry’s energy usage. Minor additional optimization may be possible, but only as long as it doesn’t affect yield. According to data from Mills and Summers, greenhouse growing can reduce energy usage by an additional 25% to 42%, depending on the climate, whereas growing outdoors would reduce it by a whopping 96%. But although the hemp industry can achieve profitability with outdoor grows, the high-THC strains of cannabis are more temperamental with their habitat requirements. Canadian horticulturist Ernest Small explains that these plants did not evolve naturally in the wild but were selectively propagated and cultivated to have higher THC-to-CBD ratios. They are also carefully bred to produce fewer seeds because the plant’s physiology dictates that although seed production enhances survival in the wild, it diminishes the generation of cannabinoids.

The select strains of cannabis buds sold by some companies can yield nearly 30% THC by weight of the dried flower. To achieve that level requires carefully controlling the environment, an easier task to achieve indoors.

One feature missing from outdoor grows and from greenhouses is tight control of the day/night cycle, which allows for adjusting the photoperiod to the optimum amount of darkness required to stimulate flowering and THC production. Avoiding seasonal fluctuations in light and temperature markedly increases profitability and is possible only when growing indoors, allowing up to six harvests per year versus one or two harvests outdoors.

At present, there is one company, Culta, which has publicized outdoor growing of cannabis in the mid-Atlantic region. Yet it is clear from data on Culta’s website that the majority of its product is still grown indoors and that most of its outdoor crop is covered by a retractable greenhouse for a good portion of the year, increasing the associated carbon dioxide generation during those times.

This November, Marylanders will have their chance to decide whether this high-carbon-footprint industry gets to expand into their state. Do they care about climate change, or don’t they?

Christine L. Miller, a retired neuroscience researcher, holds a Ph.D. in pharmacology. She is a volunteer for Smart Approaches to Marijuana-Maryland.