As cannabis legalization continues its march across the country and investment in legal cannabis continues to grow, many previously veiled aspects of cannabis cultivation have come to light, including a surprisingly damaging environmental cost. High water and energy usage, pesticides and fertilizer poisoning, degradation of public lands and potential ozone effects have all been linked to cannabis cultivation.
In the quest for quality, some professional growers employ vast artificial greenhouses where recreating the sun requires vast amounts of electricity. In Colorado, moving cannabis production outdoors would save an estimated 1.3% of the state’s total carbon emissions, a carbon footprint near that of the state’s entire coal industry at 1.8%. A recent study found that the median carbon footprint of a kilogram of dried cannabis is roughly equivalent to a 9,000- mile car journey. Additionally, a single cannabis plant needs almost 22 liters of water per day during the growing season, a consumption rate of 3 billion liters of water per square kilometer of greenhouse cultivation, putting a strain on already scant water supplies.
Outdoor grows may seem like an obvious solution to the disproportionate resource consumption of indoor grows, but they also present a host of environmental issues. It has been found that many illegal growing operations, including those which trespass in national forests, use banned pesticides, such as bromethalin and carbofuran. Ecologist Greta Wengert of the Integral Ecology Research Center described the problem: “A quarter teaspoon [of carbofuran] could kill a 600-pound black bear. So obviously just a tiny amount can kill a human. It remains in an ecosystem for a long period of time.” These pesticides travel up the food chain and become more concentrated in living tissue, presenting a critical problem for predators. Wildlife ecologist Mourad Gabriel uses fishers (small carnivores in the weasel family) to demonstrate this damage, finding that 85% of California’s fishers have been exposed to rodenticide, which is especially damaging to them as fetuses, and infants receive the toxins in utero and again through the mother’s milk. The problem is not isolated to fishers. Wengert reported that “the mountain lion population in California is exposed to anticoagulant rodenticides at a rate well over 90%.” She continued, “we have detected [carbofuran] in the soil, in cannabis plants, in native vegetation, the water, the infrastructure. You name it, we have detected it. It’s horrible.”
This raises the question: How do I reduce the impact of my cannabis consumption? An overarching solution is to continue efforts to legalize marijuana. Jennifer Carah, senior scientist at the Nature Conservancy of California, explained “the black market is not going away, but to the degree that we can entice growers into the legal market, their agricultural practices can be regulated like other agricultural crops, which will go a long way to addressing potential environmental impacts.” If marijuana production and sale is incorporated into legislation, regulations — including environmental protections — can be applied to this industry, allowing for more significant allocation of resources and attention to these pressing issues.