Marijuana’s High Environmental Burden

Guest Post By Hailey Summers, 2019-2020 Sustainability Leadership Fellow and Ph.D. Student in the Department of Mechanical Engineering

Our desires as consumers are changing. We are wanting to know the origin of things we consume and how they are made. Generally, consumers want to better understand a product’s impact on the environment, often concerned with greenhouse gas emissions. Regarding food in particular, shifting to vegetarianism or veganism is becoming more and more popular as we learn that our consumption of meat, poultry, fish and dairy significantly contributes to global warming.

A typical commercial marijuana grow facility. Source:

Yet, in this cultural shift, there is one consumable that is commonly overlooked when it comes to environmental impact: marijuana. Yes, marijuana, the now legal recreational drug commonly associated with hippies, tree-huggers and the ever-so-popular Earth Day. You may be asking, “what’s the big deal? Marijuana comes from plants and I know how plants grow.” Well, here at Colorado State University, we investigated the environmental impact of traditional marijuana cultivation practices. The results might surprise you.

Since recreational legalization, the marijuana industry has seen exponential growth.  In Colorado alone, more than one million pounds of marijuana is grown annually. However, more than 80% of that one million pounds is grown indoors. That’s right, plants, being grown inside warehouse-like buildings without access to the sun. This requires energy intense grow lights, fans to circulate air and strengthen stems, carbon dioxide gas to increase plant growth and sophisticated equipment to maintain a comfortable temperature and humidity. These are only a few of the environmental control systems required to grow marijuana plants indoors. The majority of such systems require energy from electricity or natural gas to operate. Considering this energy is primarily made through combustion of fossil fuels, you may be starting to connect the dots here, realizing that this form of artificial plant production might not be so environmentally friendly.

At CSU, we worked with local growers in the state to understand not only the energy requirements for marijuana plants, but also the amount of water, fertilizers, pesticides, soil, waste, etc. used in producing marijuana. Many of these materials release greenhouse gas emissions when they are manufactured, and these upstream emissions must be counted to fully understand marijuana’s carbon footprint. While gathering these data, we developed a tool to quantify greenhouse gases not only in Colorado, but across the U.S. Geographic location is important because a comfortable indoor climate must be maintained for the plants regardless of what the weather is doing outside, resulting in a variety of energy demands for the heating, ventilation and air conditioning equipment.

The typical marijuana grow room layout highlighting the multitude of systems required to grow plants in an artificial, indoor environment. Source:

Additionally, geography is important when considering variations in electricity generation from fossil fuel versus renewable energy sources. Results indicate that the worst locations for growing marijuana indoors in the U.S. are Alaska, midwestern states and the Colorado Rockies. This is primarily due to climate; these places tend to be cold and dry, while marijuana plants want to be hot and humid. Furthermore, electricity in these regions is primarily generated through fossil fuel combustion, resulting in large amounts of greenhouse gas emissions. Areas such as California, the Pacific Northwest and Atlantic Northeast are better suited due to limited need for climate manipulation and lower electricity generation emissions.

Despite regional variations, we found that greenhouse gas emissions from indoor marijuana cultivation are substantial regardless of where it is grown. In fact, when it comes to greenhouse gas emissions, our results show that smoking one cannabis joint comprised of indoor grown marijuana is worse than eating a hamburger! Yes, if you consume a typical joint from a dispensary, this will result in more greenhouse gas emissions than if you consume a hamburger at your favorite dive bar.

So, what can be done? The industry is aware of their carbon footprint and internally things are starting to shift. More and more, growers are switching to LED grow lights and trying to nutrients responsibly, for example. Similar to food certifications such as USDA Organic, Fair Trade and Rainforest Alliance Certified, marijuana is looking to find ways to certify their product as sustainable. Currently, the only certification for marijuana is the Clean Green certification, which is focused on greenhouse gas reduction through responsible product and electricity sourcing. However, this certification minimally addresses practices to reduce overall energy consumption, which accounts for more than 60% of total greenhouse gas emissions from indoor marijuana growth. Certifications should be focused on reducing energy usage from lighting, heating, ventilation and air conditioning if growers truly want to reduce greenhouse gas emissions. Quite possibly the easiest way to lower energy consumption would be to grow marijuana in a greenhouse or outdoors. Although, these growing practices are not entirely free of environmental burden either; concerns include illegal water diversion, nutrient runoff, deforestation and death of unintended target animals through rodenticides. Furthermore, making the shift to outdoor growth would require more than just a certification, it would require changing the law. In Colorado for example, 62 of 64 counties legally require commercial marijuana to be grown indoors. So, as you have learned, the path to sustainable marijuana is not an easy one. However, considering the significant greenhouse gas emissions from current indoor growth practices, focus should be directed toward minimizing the industries impact.

Growing marijuana in your backyard is quite possibly the most sustainable option we have currently. Visit the Modern Farmer for beginner tips! Source:

This blog might be a little sad for some readers, but it’s time consumers understand the dark side of marijuana. After all, we are living in a time when consumers want the truth about where their products come from, remember? So if you are an environmentally-conscious individual, maybe a self-proclaimed tree-hugger, proud vegetarian or vegan, I ask you to ponder these findings next time you consider consuming marijuana from a dispensary. If you truly want to be a green marijuana user, you should consider growing marijuana in your back yard using the power of the sun. Trust me, it’s super easy; after all, marijuana is a weed!

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