Cannabis Science


The Environmental Impacts from Growing Cannabis

The rising tide of marijuana legalization has opened the door to a global cannabis industry. As countries try to regulate this once-illicit plant, they cannot ignore the environmental impact of growing it in the shadows for years. 

Legalisation has also highlighted the contributions of growers in California who farm their crops sustainably (and legally) under the sun. These stewards of the land provide a model of responsible use of natural resources in cannabis farming. They need support so their lessons can influence the next generation of farmers and, and the proceeds from legal weed can make a positive impact on the environment. These farmers are mostly located in northern California’s Emerald Triangle: Mendocino, Trinity, and Humboldt county.

On the regulatory side, the plant’s legal status has made “official” (i.e. government-approved) cannabis research difficult, hindering the progress that could minimize the ecological effects of marijuana cultivation. There is also little government support for farmers who grow responsibly.

We will explore ways farming cannabis affects the environment and why farmers who use regenerative, sustainable practices deserve support.

How Prohibition and Secrecy Paved the Road to Neglect

Long before any thoughts of legalisation, cannabis cultivators headed to the hills to escape scrutiny from the law. After decades of operating like this, it’s clear that the secrecy some farmers benefited from also hid poor practices.

The United Nations Office of Drugs and Crime reported cannabis production in 151 countries between 2010 and 2018 (UNODC, 2020). Most of these operations are outdoor sites, placing a considerable strain on the land. Outdoor sites require fewer inputs and are cheaper to establish and operate than indoor or mixed-light grows but the need for secrecy may require location in ecologically fragile areas.

The plant’s legal status has made it difficult for lawmakers to set regulations for cultivation and consumption, never mind laws that would place the environment’s best interest front and center. Some ways cannabis farms impact their local environments are through water and land use, pesticide use, and energy consumption.

Land Use

Outdoor cannabis cultivators in remote, forested areas clear the land of trees and flatten ridges to create usable space. This isn’t as damaging as timber harvesting, but there is a cost to the local ecology.

Landscape perforation – creating openings in the forest for land use – reduces inner areas of the forest and increases open edges. For local wildlife, this means habitat loss and exposure to pollution.

“Trespass grows” are illegal outdoor cultivation operations often found in public lands, national forests, or tribal territories in the United States which are usually also unspoiled wildlife habitats. Trespass grows hinder conservation efforts by damaging the local ecology. Environmental groups have reported increased risk to their personnel as growers may resort to violence to discourage visitors.

In 2016, Berkeley-based specialist Van Butsic surveyed cannabis cultivation sites in northern California. His team mapped out over four thousand grow sites, most of which were “close to streams, far from roads and on steep slopes” (Scoy, 2016). The water needs of these operations put tremendous pressure on populations of steelhead trout and Chinook salmon, two species of fish listed as threatened species.

Water Use

Irrigation is of utmost importance to farmers’ growing operations, regardless of the crop. This is a problem in semiarid regions of the world the climate change era. Summers are hotter, drier, and droughts (and wildfires) are occurring with more frequency and greater intensity, so more water is needed.

In drought-inclined regions, the water requirements of cannabis plants exceed the amount of water that is available. This can lead to the draining of streams and the drastic reduction of surface water, which is extremely harmful to aquatic life and watersheds. Some illicit operators go to great lengths to acquire and utilise water resources.

In one area of the Emerald Triangle, the non-profit Integral Ecology Research Center removed more than fifty miles of lines that diverted nearly half a million gallons of water a day from local waterways to water illegally grown plants (Grant et al, 2017). IERC also oversaw the removal of more than 60,000lbs of trash, fertiliser, and pesticides from 29 different sites.

Pesticide Use

Humans began using pesticides to protect valuable crops thousands of years ago. Intensified pesticide use in modern farming has been associated with many negative effects on the environment and public health for years.
Pesticides affect the environment, the cultivator (and any workers), and the consumer.

The treatment of rodents presents an example of the dangers of pesticide application. Rodents are an enduring pest to cannabis over the growing season. During periods of drought when plants are heavily watered, rodents damage the stalks of cannabis plants looking for moisture. This causes a slow death for the plants as they gradually lose the ability to absorb water. Rodents may also cause damage to water lines, which can be dangerous during the dry season.

Anticoagulant rodenticides (or ARs) are chemicals formulated to cull rodents. These highly toxic chemicals prevent blood clot formation, and when applied to deter pests, can be consumed by other wildlife. IERC executive director Mourad Gabriel began attending raids on trespass grows in 2011 and found that pacific fishers, an endangered relative of the weasel, were dying from AR exposure.

There is limited standardised testing for pesticides and other chemicals used in legal cannabis cultivation (Wartenberg et al, 2021). Conversely, there is a large variety of chemicals farmers use to keep their plants healthy and safe from pests.

This means that cultivation workers and consumers risk exposure to trace elements of dangerous compounds.

Regenerative farmers may apply compost teas to minimise pesticide use. Integrated pest management is another example of a biologically-derived solution used by regenerative farmers that is kinder to the land.

Energy Use

Indoor cultivation facilities rely on large amounts of electrical energy to power their high-intensity lights, irrigation systems, and temperature and humidity control. In their 2021 report, Wartenberg et al estimated that indoor cultivators used up to five times more electricity compared to greenhouse vegetable, fruit, and flower production facilities in Europe, Canada, and North Africa. This is significant in urban areas, where energy-intensive indoor cannabis operations can lead to ozone formation, air pollution, and raise the carbon footprint.

As outdoor farmers attest, the most energy-efficient way to produce cannabis at scale is to grow it under the sun. Regenerative farmers take this one step further by growing off-grid and using solar energy to power supplemental lights instead of carbon dioxide emitting gas generators.

How to Limit the Environmental Impact of Cannabis Cultivation

Informed consumers, incentives for growers to cultivate in an ecologically responsible way, and best practices can limit the environmental impact of growing cannabis.

There are legal cannabis growers who consider sustainable practices and land stewardship as central to their identities as the potent flowers and exotic terpenes they produce. This information is available online for consumers to research and should be included in any conversation about high-quality products. The cannabis market should be more than just THC content, jar appeal, or flavour-of-the-month strain.

The current era of legalisation has done plenty to help legal cannabis producers, but there is more work to do. In the United States, the legal status of cannabis makes it impossible for farmers to apply for subsidies and be eligible for tax incentives based on responsible practice. Consumers who do their research can help these farms by voting with their wallets and keeping them afloat.

Regulatory bodies should also make the time and effort to study the practices employed by responsible cultivators and standardise them to help others get on board throughout the marijuana industry. As we have seen with other crops, best practices can minimise the impact of water and land use, pesticide pollution, and energy use.

Ultimately, full legalisation of cannabis will provide opportunities for governments to take the lead on minimising the effects of cultivation. Grants and funding can be made available to organisations and non-profits to conduct more research. Laws for emissions and pesticide use can reduce greenhouse gas emissions. There are plenty of opportunities for science to improve responsible cannabis cultivation, and for cannabis use to support a balanced relationship with the ecosystem – it just needs to be given the chance.

Post author
Martin is a production horticulturist with experience in commercial cannabis cultivation and sustainable farming from his time with Emerald Cup Award-winning farmers Esensia Gardens in northern California's Emerald Triangle.
See more from Martin

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