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Cannabis legalization: what are the environmental impacts


Legalization of cannabis would help to better protect the environment, avoid pollution and defend eco-systems?

This is what emerges from several studies carried out in the United States on the issue.

The production and marketing of cannabis is an economic activity of significant size.


Although illegal in most states of the world, the cannabis trade is estimated to be worth about $150 billion in revenue.. with about 200 million consumers.

It is also an "industry" around which important issues (public health, public safety, revenues, traffic management...) are built.

cannabis legalization environment

In recent years, specialists in the field have been wondering about the best way to manage these issues:

To continue to ban cannabis, to fight against its production, or to legalize production, trade or consumption., in order to have better control over the industry.

Few States and public authorities in the world have so far embarked on the second option.

But one thing might perhaps change their minds: in addition to the possible economic benefits for public authorities. Legalizing cannabis could have beneficial effects on the environment and the planet.

1. The environmental impact of cannabis

In a previous article, we deciphered the enormous environmental impact of tobacco.

Between the production of tobacco plants, their drying and processing, the transportation of the merchandise, the manufacture of cigarettes, filters and rolling leaves., tobacco is a very polluting and environmentally harmful industry.

Generally speaking, the cannabis industry poses the same problems as the tobacco industry:

Cannabis plants have to be grown, which requires inputs, pesticides and fertilizers.

Cannabis cultivation is very water- and even energy-intensive. In the end, it is estimated that smoking one cannabis joint is equivalent to emitting about 900 g of CO2 into the atmosphere. If all the impacts of the production chain and life cycle are taken into account.

And we are only talking about CO2 here: that is without counting the other various other pollutions generated by the production of cannabis throughout the chain.

But then, how could legalizing cannabis help reduce this environmental impact? And what if legalization would help to redefine more ecological conditions of production and marketing?

2. Indoor cannabis cultivation:

Pollution, energy waste and environmental impact

It is important to know that a large part of the environmental impact of cannabis is linked to its production conditions.

First of all, indoor (indoor growing, is hotboxing the planet) poses serious problems in environmental terms. Since cannabis cultivation is illegal in a majority of countries in the world.

Many producers have launched indoor production areas in order to avoid being spotted by the aerial or satellite controls of drug enforcement authorities.. (this is particularly the case for individual productions, but also for larger scale productions).

The problem is that cannabis is an equatorial plant, which therefore requires a significant amount of water and light to grow properly.

Therefore, when growing cannabis indoors, care must be taken to provide this water and light, including irrigation systems and UV lamps.

cannabis cultivation

It also requires temperature regulators and air purifiers and dehumidifiers, in order to maintain the plants in good conditions.

In the end, all this consumes a lot of energy. It is thus estimated that in the United States, the indoor culture of cannabis represents alone 1% of the total electric consumption of the country.

Growing 4 cannabis plants indoors would result in electricity consumption equivalent to that of 29 refrigerators.

In California, where production is among the highest in the United States., it is estimated that a little less than 10% of total household electricity consumption is related to indoor cannabis cultivation!

The production of 1 kg of cannabis indoors would thus lead to the direct and indirect emission of more than 4.6 kg of CO2.

This is about the same amount of emissions as the production of 1 kg of ham for example, or 15 kg of strawberries.

In the end, in the United States the production of cannabis indoors would be equivalent to the pollution generated by 3 million cars.

Legalizing the production would make it possible to put back a good part of the cultivation outdoors., and thus to reduce the energy consumption linked to indoor cultivation.

Of course, some crops would remain indoors (in less favorable climates., or for productions that require a stricter control of the cultivation process, or for questions of productivity). But for part of the demand, outdoor cultivation could suffice.

3. Legalizing to avoid the destruction of natural areas

The other big problem of cannabis production is that cultivation. Even outdoors, is extremely polluting because it is wild and takes place in poorly controlled conditions.

First of all, to escape police controls, growers look for remote lands, away from urban spaces.

It is estimated that 31,000 hectares are devoted to the wild cultivation of marijuana in California alone.

And the vast majority of these outdoor-grown plants are located in wild forested areas, or even in the heart of protected or sensitive areas.

In the United States, according to the latest census, 71 national forests in 21 states are believed to be home to illegal crops.

This means that farmers must first clear and destroy the forests, and thus destroy natural areas.

This inevitably affects biodiversity and the local ecosystem.

4. Better control of production conditions

But that's not all: under the pressure of controls, traffickers are forced to be highly mobile.

They must therefore be capable of very fast yields, so that they can quickly relocate their production sites without being detected by the police.

The results..? To increase yields, farmers are massively transforming the ecosystem:

they are building major irrigation systems by diverting rivers, dams that are likely to disrupt ecosystems.

They also massively use pesticides, fertilizers and herbicides to facilitate plant growth.

In 2011, for example, in the National Forests of Mendocino, 56 illegal production sites were dismantled, and 23 tons of waste., 1 ton of fertilizer, 30 kg of pesticides and herbicides were found there, as well as 10 km of illegal irrigation and 13 dams.

The use of toxic products and pesticides (in much larger quantities than necessary), inevitably leads to contamination of the ecosystem:

In the Sierra National Forest in California, 70% of birds (especially owls) are reported to be contaminated by pesticides, but also 76% of fish.

 There has also been a drastic decrease in the population of certain mammals such as fisherfishes., linked to poisoning by pesticides used in illegal plantations.


The use of artisanal irrigation systems is drying up rivers and local water reserves since cannabis is one of the most water-intensive crops., (a plant requires about 23 liters of water per day).

All this has even prompted some US Senators to publish an open letter on their concerns… about the environmental damage caused by illegal cannabis plantations.

5. Cannabis is a regulated crop like any other

According to several studies, including an analysis published in the Columbia Journal of Environmental Law. Legalizing cannabis production would allow for better control of production practices.

In fact, cannabis would become a crop like any other, subject to agricultural regulations and to controls on water quality and the use of chemicals.

This would first reduce the pressure on ecosystems and biodiversity by controlling production areas.

It would reduce the use of pesticides by implementing reasoned production; it would reduce the impact of landscape transformations with approved irrigation systems...

In short, legalization would allow environmental but also health authorities to have control over production conditions… rather than letting traffickers manage wild and extremely polluting productions.

6. Cumulative beneficial effects

The reduction of wild pollution, the legalization of cannabis would make it possible to avoid the effects of transfer of means.

Rather than investing millions each year in programs to combat illegal production sites, governments could allocate these resources., (financial, logistical and human) to environmental protection programs.

The financial resources used by forest protection institutions to dismantle sites could thus be better used elsewhere.

Indeed, when a production site is discovered by the anti-drug authorities, the plants are either burnt or destroyed using powerful herbicides.

This therefore contributes either to air pollution or to soil and ecosystem pollution.

In the United States in 2013, nearly 4 million cannabis plants were eradicated in this way, thanks in particular to the use of powerful herbicides...

Another beneficial effect to consider is the reduction of transportation.

A legalization of cannabis could allow local production to develop and thus avoid that trucks, cars, airplanes… or other boats filled with cannabis have to cross borders illegally to supply national markets.

Above all, it would avoid the collateral damage associated with trafficking.

 For example, it is known that South American cartels, in order to transport their merchandise. Hide their goods in the middle of very toxic products containing volatile organic compounds.

 This allows the smell of cannabis to be covered by that of chemicals and avoid being spotted during checks with dogs.

 The problem is that these products are then thrown away and dumped, often in the wild and in areas rich in biodiversity… such as on the US-Mexico border.


A study conducted by a dozen environmental scientists under the direction of Oxford University concluded in 2014 that… the legalization of cannabis would not only allow for a better control of production, eliminate the harmful effects of wild cultivation.

But also allow for a better allocation of resources in the protection of the environment.

Indeed, if we consider that each year the fight against cannabis costs the State more than half a billion Euros in terms of infrastructure and police operations.

This represents as much money as could be allocated to the protection of biodiversity for example.

In concrete terms this would make it possible to multiply by 3 the State budget allocated to water management and biodiversity… which was only 276 million in 2015.

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