With medical marijuana now legal in 20 US states—and recreational marijuana legal in four states plus the District of Columbia— researchers are starting to ask: just how green is marijuana? So far, policymakers have assumed that cultivating marijuana has only minor environmental consequences, according to a recent article in BioScience. In practice, however, marijuana plantations can have devastating environmental effects, argue the study’s authors. Marijuana cultivation requires large quantities of water, and illicit growing operations—which sometimes supply legal marijuana dispensaries—encourage poaching and leave behind trash and even human waste.
“The [marijuana] plant itself is just plain thirsty,” says study co-author David Dralle, a UC Berkeley graduate student in the Department of Environmental Engineering. “When you consider that this thirsty crop is largely cultivated in sensitive, biodiverse areas during California’s dry, Mediterranean summer, it’s not hard to see why marijuana is arguably one of the most environmentally harmful crops grown in the state.”
California produces an estimated 60% of the marijuana consumed in the United States. Even conservative estimates suggest that marijuana is the largest cash crop in California, with sales upward of $10 billion. Yet as state-level legalization rapidly spreads across the country, all cultivation of marijuana remains illegal under federal law, throwing a wrench into regulatory policy.
According to Dralle, taxes on crops ought to fund regulation—but with marijuana, “not one cent has traditionally been used for environmental restoration or protection.” It’s high time, the authors argue, for environmental regulations to catch up.