As more states legalize marijuana, its commercial production will increase. These cultivation activities may not only get customers high, they can also drive up the planet’s temperature.
A new study published in Nature Sustainability on Monday aims to quantify the climate impact of indoor cannabis cultivation across the country. The authors, who are researchers at Colorado State University, wanted to find out how greenhouse gas intensive these operations would be if they were set up somewhere in the country.
“Policymakers and consumers don’t pay much attention to the environmental impacts of the cannabis industry,” Jason Quinn, an associate professor of themechanical engineering Department at Colorado State University and lead author of the study, wrote in an email.There is little or no regulation of emissions when growing cannabis indoors. Consumers do not look at the environmental impact either. This industry is developing and expanding very quickly without taking the environment into account. “
Many cannabis growers prefer indoor cultivation to outdoor cultivation as it provides more control over the plants’ habitats and greater safety. But these indoor activities have a cost to the climate, as they require heating, ventilation and air conditioning to maintain the ideal temperature and humidity, and high intensity grow lights that stay on around the clock. They also often pump one regular supply of carbon dioxide to accelerate plant growth and increase profit.
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To find out how carbon-intensive cannabis growing is, the team of researchers developed a model to track the energy and materials used for the type of warehouse-style indoor cultivation that 41% of American growers use. The model is designed to recreate a truly typical warehouse, complete with HVAC, grow lights, pesticides and fungicides, water applied via drip irrigation “at an average rate of 3.8 liters per plant per day”, and more.
Because temperatures and humidity vary widely across the US, the authors’ model calculated the energy required to maintain these indoor climate conditions by leveraging a year of weather data from more than 1,000 locations across the country. Using grid emission data from around the country, the model then showed the greenhouse gas emissions that would produce all that required energy. In addition, the model took into account the “upstream” emissions from the production and transportation of water, fertilizers, fungicides, and bottled carbon dioxide to grow homes, as well as tracked the “downstream” greenhouse gas pollution from all the waste these operations sent to landfills. send. .
Taken together, the authors found that cumulative greenhouse gas emissions from one of these indoor growing warehouses were between 5,033 pounds (2,283 kilograms) and 11,428 pounds (5,184 kilograms) of carbon equivalent per every 2.2 pounds (1 kilogram) of dried flower. . In other words, the eighth weed you buy (legally, of course) comes with an ecological footprint of 19 kilos.
However, the authors say it doesn’t have to ruin your buzz. We don’t have to give up growing weed. We just need to start shifting the industry to more outdoor growing activities.
“If indoor cannabis cultivation were fully converted to outdoor production, these preliminary estimates show that the state of Colorado, for example, would see a reduction of more than 1.3% in annual [greenhouse gas] emissions, ”says the study. That means that only Colorado would see a 2.3 million tons carbon equivalent reduction each year, which is roughly equivalent to emissions from the state’s entire mining sector, according to the study.
The results of the study suggest that 80% of greenhouse gas emissions caused by growing cannabis are caused by ’caused by practices directly related to indoor growing methods, particularly indoor environmental control, high intensity grow lights and the supply of carbon dioxide for increased plant growth. “Yes, growing outdoors still requires materials and equipment to be transported, and it still results in waste being sent to landfills – problems we need to keep working on. But it’s much less energy intensive, the authors found.
Of course, growing outdoors may not be possible in every part of the country. So within states, the authors also identified locations where indoor cultivation is relatively less energy intensive. In Colorado, for example, “the practice of growing cannabis in Leadville leads to 19% more greenhouse gas emissions than in Pueblo,” because the former tends to be colder. In climates where outdoor growing could work, policymakers should take steps to usher in the transition. That includes changing regulations and destination codes to enable more of these outdoor activities.
But all of this is just a first step, say the authors. Much more research needs to be done on how to make this fast-growing industry more sustainable.