Although the public may assume cannabis cultivation is small-scale and sustainable, the truth is cannabis production is now an industrial-scale endeavor with industrial-sized environmental impacts.

The scale of cannabis' emissions problem has been laid out through a new, comprehensive study published in Nature Sustainability. Published in 2021, “The greenhouse gas emissions of indoor cannabis production in the United States” is the first study to quantify the emissions per kilogram of cannabis produced by indoor growers across the country. The results finally detail the massive carbon footprint for which this booming industry is responsible.

Heating, Air Conditioning, and Ventilation: The Real Energy Hogs

The researchers behind this explosive new study sought to “analyze the energy and materials required to grow cannabis indoors” alongside the “corresponding greenhouse gas (GHG) emissions using life cycle assessment methodology.” In essence, how much greenhouse gas is produced in an indoor facility, broken down into emissions per kilogram.

Lead researcher Hailey Summers and her team expected substantial emissions, but the results seem to have shaken even their wildest predictions. Assessing the emissions over the complete life cycle of one kilogram of dried flower, Summers' team discovered greenhouse gas emissions ranging from 2,283 to 5,184 kg per CO2-equivalent. 

In comparison, beef production, which is primarily considered one of the worst foods for the planet in terms of greenhouse gas, produces only 60 kg of emissions per kilogram. The average car, driven by an average person, produces 4,600 kg of CO2 per year, which is still below the top end of the indoor cannabis range.

Beyond the staggering level of emissions from indoor cultivation, another interesting discovery made by the team was the source of these emissions. Many would assume that the high-intensity indoor lighting required within these facilities was found to be the primary reason for energy consumption and their substantial carbon footprint.

However, this report discovered that the environmental controls, like air conditioning, ventilation, and heating, were some of the largest energy hogs within a commercial facility. Depending on location, commercial cultivators may need to employ heaters (like in Minnesota) or air conditioning and dehumidifiers (as in Florida) for year-round production.

Indoor Cultivation the Primary Culprit for Cannabis' Massive Carbon Footprint

Summers' recent study explored the emissions from indoor cultivation facilities, but indoor cultivation is only one of many ways to grow cannabis commercially. Greenhouse and outdoor grows are viable alternatives, which seem to have a substantially lower environmental impact.

As per Colorado State University Source, the New Frontier Data 2018 Cannabis Energy Report estimated a kilogram of greenhouse-grown dried flower produced 326.6 kg of CO2, while outdoor produced only 22.7 kg.

According to the Cannabis Business Times 2020 State of the Industry report, indoor/warehouse production has fallen by 20 percent since 2016. In turn, greenhouse and outdoor facilities have increased by seven and five percent, respectively. In 2020, this report found that 60 percent of producers still grow in warehouses, but this has fallen substantially from 80 percent in 2016.

While many growers may be shifting towards outdoor and greenhouse operations for financial reasons, the emissions report makes another case to switch: Indoor and warehouse operations are responsible for 15 times more CO2 than their greenhouse or outdoor counterparts. These facilities are not energy efficient by any measure.

Growing outdoors and in greenhouses not only eliminates the need for lights (although some greenhouses do supplement), it also reduces the emissions produced by environmental controls. Seasonal growing means no need for heaters, air conditioners, or even the CO2 supplement used for boosting growth.

Consumer Demands Could Make the Market Greener

As the national cannabis market matures, including continued mergers and acquisitions, producers will need to dial in their energy consumption as a means to maintain a competitive edge.

Reducing costs per pound may begin as an economic decision for these producers, but it could lead to a smaller carbon footprint. After all, less energy consumption would lead to lower emissions.

Also, the demand for environmentally friendly products within other consumer industries could begin to influence cannabis producers. Just like consumers are looking for better packaging solutions, if they demand a zero-emissions gram of flower, the industry will follow.

This recent study has exposed the massive impact a booming cannabis industry is having on the environment. The research team is now seeking additional funding to help continue their work and expand into exploring the footprint for outdoor operations.