Not so green after all? The shocking truth of cannabis’ carbon footprint

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  • Is cannabis eco-friendly? Intuitively, most of us would say that surely it must be. After all, weed is inextricably linked in our minds with flower power, the hippy movement and all the associations with eco-friendly living that accompany it. The facts, therefore, could come as something of a shock, and it turns out that cultivating a cannabis plant is about as eco-friendly as your average poorly maintained 1960s VW Microbus.

    Greenhouse emissions through the roof

    Last month, Nature Sustainability published the results of a study on how legalization of cannabis in specific states has affected state greenhouse emissions, and the results make sobering reading. Growing just one ounce of cannabis produces the same emissions as burning a tank full of gasoline in your car – in some states, it is even higher, and equivalent to around 16 gallons.

    When you consider that the average cannabis plant yields around 15 ounces of weed, it becomes immediately clear that green is perhaps the most inappropriate of all the many slang names that cannabis has.

    Home growing on the rise

    The statistics don’t just fly in the face of the way we perceive cannabis users. They are also at odds with the usual conception that growing your own products is more environmentally responsible than buying them from elsewhere. In the case of cannabis, there are also financial drivers that encourage home cultivation. The 15 ounces of weed that a plant will produce would cost an eye-watering $5,000 at average dispensary prices.

    Little wonder, then, that so many people choose to invest a few hundred dollars in setting up their own grow rooms, then scouring sites like to purchase the seeds for their favorite strains of weed. In fact, the Nature Sustainability report indicates that around 50 percent of the demand that legalization has generated is being met by home growing.

    Why so high?

    The main source of emissions is the electricity used to power grow lamps and equipment to maintain the perfect environmental conditions in terms of temperature and humidity in grow rooms. Some growers also pipe in carbon monoxide to accelerate growth, a practice that carries all sorts of additional risks on top of the environmental factors.

    Jason Quinn, from Colorado State University, is a senior author of the study. He feels that neither lawmakers nor consumers are paying sufficient attention to the environmental impact of America’s burgeoning cannabis industry. He fears the speed at which the industry is growing could create an ecological disaster unless education and regulation on emissions from growing cannabis are given priority.

    What can be done?

    There are actions that individual growers can take, such as opting for more efficient equipment – choosing LED lights over fluorescent or HID versions is a perfect example. Encouraging growers to opt for greenhouses instead of growing indoors could also have a significant impact. In the first instance, however, the conversation needs to begin in earnest so that future crops of green will be fully deserving of the name.

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