In-depth


Legalizing marijuana is hurting the environment

John Dyer
16 November 2017 | updated 20 November 2017

A number of American states have legalized marijuana in some form or another. But while marijuana farmers can celebrate, the environment is taking a hit as cannabis cultivation replaces forests and leads to habitat loss.

Boston. The Emerald Triangle in Humbold County is a forest-rich region in northern California. Its nickname comes from the emerald green colour of the marijuana plants growing across the region – even visible from Google Earth images. 

The region also served as the basis for a study on the impact of marijuana cultivation on the natural environment.

Worse than logging

The findings are alarming, said Jake Brenner, a geographer at Ithaca College in upstate New York. 

Writing in Frontiers in Ecology and the Environment, he and his colleagues said that weed growing is destroying habitats, altering streams and causing soil erosion and landslides on a scale that’s proportionally worse than logging.

Growing cannabis on one acre of land causes 1.5 times more forest loss and 2.5 times more so-called forest fragmentation – ruining habitats, breaking up contiguous wilderness – than cutting down trees for timber, the researchers found.

“The hot spots of growing tend to be on steep slopes, far from roads and close to the headwaters of tributary streams that are critical fish habitat,” wrote Brenner. 

Lack of adequate regulations

The problem is largely due to the lack of adequate regulations on weed growing, added Brenner, who said government officials could stem the problem if they applied rules to weed that are now routine for other types of agriculture.

Although a number of states have now legalized the consumption and cultivation of cannabis beyond mere medical use, marijuana nonetheless remains an illicit substance under federal law. This explains why cannabis farmers prefer to grow their crops in remote, even wild areas.

“It’s not that cannabis uses more water than other crops. It’s not that it clears more land than other crops,” he said. “But the way that it is arrayed on the landscape puts those impacts on highly sensitive areas.”

Cannabis more lucrative than logging

In Humboldt, logging is a $71 million a year industry, according to the study. Cannabis production is estimated as generating $300 million. Nationwide, legal weed is worth more than $7.6 billion annually, the researcher wrote. That figure is expected to balloon to $21 billion in the next few years alone.

Brenner said he was ambivalent about legalization, though he believed it could provide sustainable economic development for rural areas that need investment and jobs.

“I would like to see Humboldt Country thrive and, if cannabis is the way to do that, I would not have a problem with that as long as it doesn’t run into the same environmental destruction issues that other agricultural practices tend to run into,” he said.

Reefer madness still a taboo

He hoped his research would help policymakers take action to curb the harmful consequences of weed growing while emphasizing the positive. Unfortunately, he said, politicians often fail to entertain honest debates on the topic.

“The ‘reefer madness’ taboo is very much with us today,” said Brenner, referring to the 1939 propaganda film that purported to show the dangers of smoking pot. 

“If we don’t start being frank with ourselves, we’re going to see fallout. What we are trying to do is head off some of those consequences in the environment arena by daylighting this phenomenon.”