Power to the pot

Global warming may give a minor twist to that classic hippie bumper sticker that quips, “Acid rain: Too bad it’s not as much fun as it sounds.” Turns out a warming climate could boost the medicinal and psychoactive properties of plants—including cannabis.

But that’s not all: Climate change also will open up higher elevations to growing weed clandestinely on public lands, a practice that’s putting increased strain on fragile ecosystems. Some say relaxed marijuana laws exacerbate the problem by bringing in more growers; others argue increased regulation and oversight will eventually lead to more responsible growing practices.

One prominent researcher who specializes in weed migration patterns in the face of climate change says marijuana grown outdoors likely will become stronger and require less water to thrive.

“If you go back to the times plants evolved on land, the average CO2 levels were 1,000 parts per million; today it’s about 400,” said Lewis Ziska, a plant physiologist with the U.S. Department of Agriculture’s Agricultural Research Service.

About 4 percent of plant species have adapted to lower CO2 levels, most of them subtropical grasses such as sorghum, corn and millet. However, most plants—including marijuana—still feel deprived of the optimal CO2 levels they were born into.

Ziska’s research suggests plants feeling deprived will benefit from rising CO2 levels because they haven’t yet adapted to the lower levels. His own and other scientists’ work indicates the medicinal qualities of these plants may be bolstered by global warming.

Retired USDA ethno-botanist James Duke says that when plants are stressed, due to circumstances such as the conditions brought on by drought, they tend to exhibit more of their medicinal properties.

Duke has seen this in his “Green Farmacy Garden” in Fulton, Md., home to more than 300 native and nonnative species of medicinal plants that have been utilized traditionally and/or researched for use in modern medicine.

“Something we learned in the garden … is that the more stress a plant gets—heat or cold or disease or just plain beating it—the more medicinal and less edible it becomes,” Duke said.

Marijuana doesn’t produce psychotropic compounds such as THC just so people can smoke it, Ziska explains. It’s a pest repellant. “Plants aren’t mobile—they can’t get up and move around—so they have to produce these chemicals to fight off pests and disease.”

The marijuana market is getting crowded. As states, including California, relax marijuana prohibitions, larger producers are rushing in, spilling onto public lands without regard for environmental rules in a bid to get rich quick.

As California enters its fourth year of drought, that intensified production is taking its toll on an already taxed water supply.

A 2014 California Department of Fish and Wildlife study of one of four watersheds within the state’s so-called Emerald Triangle (prime marijuana-growing counties of Mendocino, Humboldt and Trinity) estimated growers used nearly 63,000 gallons of water a day to irrigate 10,500 outdoor marijuana plants. That’s 9.5 million gallons per growing season out of one watershed. Depending on the creek monitored, that level of use amounts to between 21 percent and 29 percent of minimum stream flow, the amount of water necessary to preserve stream values including fish and wildlife habitat, aquatic life, water quality and aesthetic beauty.

One biologist who has been a thorn in the side of Northern California’s guerrilla pot farmers has been keeping an eye both on the political climate and the environment.

Along with colleagues at UC Davis, and the Integral Ecology Research Center, a nonprofit he helped launch to protect sensitive flora, fauna and ecosystems, Mourad Gabriel has been assessing pot farming’s toll on the environment. The journey began when he traced declining populations of the fisher—a small carnivorous mammal and member of the weasel family—to rat poisoning placed by growers to protect crops.

“The fisher was an environmental indicator that we had a problem,” Gabriel said. “I draw the analogy of a festering wound where you just see the precipice and you scratch it and notice it’s much larger and is actually this neoplastic cancerous growth that’s going through our ecosystem.”

Guerilla pot farmers—those growing on public lands as opposed to their own property—divert huge amounts of water, break trails and set up camps in fragile forest ecosystems, and they use large amounts of over-the-counter and even banned pesticides, Gabriel said.

Climate change has real potential to make the situation worse, he said.

Common practice, Gabriel said, is to tap into cold stream headwaters with half-inch and quarter-inch irrigation line, typically running up to 6 miles of pipe over a 2-mile area to water scattered patches strategically placed to confound law enforcement officials.

He shares other local biologists’ concerns that a warming climate will increase the geographic area hospitable to growing marijuana and therefore the ubiquity of guerrilla grows.

Pesticides are a big part of that threat. Bill—who grows on his own land—said he looks forward to the day when farmers who grow organically will be rewarded for their stewardship.

“Why would you pump a medicinal plant with carcinogenic petroleum products?” he asked.