Can Cannabis Reduce CO2 & Help Reverse Climate Change?

Cannabis is being legalised in more places than ever before. Some activists push for legalisation with claims of climate change benefits, but how true is it that cannabis can help prevent or reverse climate change?

The idea that cannabis cultivation can help mitigate the effects of climate change is not new. However, there is a great deal of disinformation, pseudoscience and outright propaganda from both sides of the legalisation argument. This can make it very difficult for the public to ascertain the reality behind the claims.

The monoterpene argument

A prevalent argument holds that planting cannabis alone could replace terpenes released by trees lost to deforestation. These terpenes have an important role to play in regulating atmospheric conditions. Specifically, monoterpenes (which all share the chemical formula C10H16) are of particular importance in this mechanism, although other types may also be of significance.

As monoterpenes are released, they travel up to the stratosphere, carried by convection currents, and undergo oxidation reactions with ozone, OH, and NO3 in the atmosphere to produce a range of by-products.

Our understanding of the precise mechanisms by which monoterpenes can assist in shielding the planet from the sun’s harmful UVB rays isn’t complete. However, it’s known that the products of their oxidation in the atmosphere assist in the formation of clouds, which reflect solar radiation and produce enhanced precipitation. Monoterpenes are released in higher levels in warmer weather, allowing for a localised cooling effect as clouds seed above the forest, thereby regulating its temperature.

What’s wrong with this argument?

While it’s certainly true that cannabis releases monoterpenes, the quantities and types released have not been definitively established (and vary between strains), and their specific mode of action in atmospheric regulation hasn’t been assessed. There is apparently no basis for suggesting that cannabis releases more monoterpenes than all other agricultural crops.

On the basis that cannabis does release most of the monoterpenes considered most crucial to oxidation and cloud formation (a-pinene, ß-pinene, D-limonene, myrcene, camphene, among others), there may very well be a specific role for cannabis to play, but this is far from established.

Cannabis does grow particularly fast, but the rate at which it releases terpenes isn’t understood. Plus, it may well be that there’s another, or perhaps many other, plant species that can do an equivalent or better job of releasing atmospheric monoterpenes:

Sweet chestnut

The sweet chestnut (Castanea sativa) is known to be among the highest emitters of monoterpenes, and achieves its full height of around 35 metres (and girth of around 2 m) in around 80 years. In the first 12 years, it can reach 20 m. 

Eucalypts

Eucalypts are also known to produce very high levels (the blue haze that gives the Australian Blue Mountains their name is caused by light scattering off the cloud of monoterpenes released by them), and have many applications in medicine and industry. They’re fast-growing, with up to four metres in new growth per year. 

Black Bamboo

Black bamboo (Phyllostachys nigra) grows at a rate of up to three metres per year, and is another high producer of monoterpenes, as well as having various applications in timber, fibre, food and medicine.

As such, unsourced claims such as “the cannabis plant is exceptional in producing copious amounts of 58 monoterpenes in less time, in more soil and climate conditions, with greater ecological and economic benefit than any other agricultural resource on Earth” are unscientific, and not particularly helpful to the ongoing cause for legitimising cannabis’ potential role in helping reverse climate change.

The importance of CO2

Forested regions are crucial carbon sinks, sequestering tonnes of carbon per hectare annually and thereby reducing the overall level of atmospheric CO2, while also emitting oxygen. CO2 is a known greenhouse gas, and increasing atmospheric concentration of greenhouse gases is firmly linked to anthropogenic climate change.

As deforestation continues to impact the world’s forested regions, the percentage of overall tree cover has drastically fallen. It’s thought that deforestation alone has accounted for some overall increase in global temperatures in recent decades, as it’s caused an increase in CO2 of between 12% and 20% independent of that caused by industry and other sources of atmospheric pollution.

Another oft-repeated argument holds that cannabis is a better candidate for carbon sequestration than any other plant. An article from the sensationalist website Natural News states that “the soil-restorative benefits of cannabis are virtually unmatched in nature, as this miracle plant naturally pulls in far more carbon dioxide than virtually any other tree, shrub or plant known to man”; the article goes on to quote from an obscure blog, Carbon Planet, asserting: “A field of medicinal weed will sequester around 22 tonnes of carbon dioxide per hectare”—a claim which isn’t backed up by any official source in either post.

Hemp is indeed considered a valuable carbon sequestering crop—along with many other commercial crops, such as soybean, rice, wheat, and sugarcane. However, net carbon sequestration by industrial hemp is elsewhere estimated at 0.67 tons (0.61 tonnes) per hectare per year. That’s far lower than the previous claim, and comparable to other common crops.

Hemp is an annual crop, which means that it’s harvested every year. Therefore, it’s different from trees. While annual crops have undoubted potential as carbon sinks, particularly if they aren’t ultimately burned or used as biofuel (processes which emit carbon back into the atmosphere), perennial trees are generally seen as more important in the effort to control atmospheric CO2.

Cannabis and atmospheric CO2

Interest has been shown in the ability of cannabis and many other plant species to increase their growth rate and nutrient utilisation in CO2-enriched environments. A study published in 2011 demonstrated that atmospheric concentrations of CO2 of 700ppm significantly increased net photosynthesis and water use efficiency in four high-yielding cannabis varieties compared to ambient concentrations of 390ppm; on the other hand, concentrations of 545ppm had negligible effects.

However, atmospheric concentrations of CO2 have not yet reached the magic figure of 700ppm that will allow cannabis to grow more efficiently. According to estimates, this point will be reached in around 2100 at present rates of emission. Thus, we still have over 80 years to attempt various other strategies that will potentially maintain lower concentrations.

These strategies include replanting of a large range of different plant species that are currently threatened or subject to fragmented habitats. If implemented now, reforestation schemes involving even relatively slow-growing species would still have a discernible impact in 80 years’ time. If successful, these strategies will negate the need for abundant planting of cannabis as a carbon sink.

As our understanding of the complex dynamics of carbon sequestration by terrestrial biomass grows, it’s increasingly clear that large, old trees are by far the best carbon accumulators over time. A recent study in Nature found that for the majority of tree species, the largest, oldest individuals are in fact the fastest-growing in terms of mass, and increase their carbon-sequestering capacity each year as they grow. In extreme cases, one large tree may add equivalent carbon to the forest in one year as a mid-sized tree may accumulate in its entire life to date.

So what role can cannabis play?

With properly-managed techniques, there’s no reason that cannabis and hemp should not be planted as part of a sustainable strategy for carbon sequestration. However, the question of whether any one plant is a better carbon sink or monoterpene emitter is not the correct one to ask when it comes to the issue of resolving anthropogenic climate change.

Loss of biodiversity is one of the biggest factors affecting the long-term survival of our own species and other species we depend on. Focusing on single crops to combat climate change isn’t a long-term solution.

Rather than viewing cannabis as the one plant that’s going to protect against further anthropogenic global warming, we need to look at the bigger picture. A better approach would be to seek to protect all remaining ecosystems, preserve as much biodiversity as possible, and intensify already-ongoing planting strategies that comprise a range of species appropriate to habitat and potential utilisation.

Cultivating more cannabis and hemp where appropriate would undoubtedly bring multiple benefits, but its importance should not be overstated for the purpose of winning support for legalisation. There are already plenty of good reasons for cannabis to be legalised without diluting the argument with wild claims and unsupported facts. This may just end up giving the opposition fuel to discredit the movement.

  • Disclaimer:
    Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

Comments

11 thoughts on “Can Cannabis Reduce CO2 & Help Reverse Climate Change?”

  1. Michael Floyd

    Poorly written and researched article!!! I don’t think that you truly understand the Truth behind the Tree of Life.

    I think you are highly disregarding the impact that growing the Tree of Life (Cannabis) would have on this planet. Anyone with a working nose can readily tell that cannabis produces an abundance of monoterpenes. We don’t need a Rocket Surgeon to tell us that one. At what point does one trust science over ones own intuition?
    Trees are a part of the cannabis vs. Climate Change equation anyways. I would hope that an 80 year old tree would produce more monoterpenes than a one year old Tree of Life, but we can’t plant 80 year old trees, we must wait 80 years for them to mature. Cannabis is the catalyst to start stabilizing the climate, and it will work in conjunction with all the other organisms on the Earth. If we grow more cannabis/hemp, we can stop cutting down forests for paper (to wipe our butts with). I think we should be planting the Tree of Life along with other trees. We should only cut down the Tree of Life for paper, housing, fuel, food, etc, and let the other trees grow to their full maturity. The Tree of Life can grow 15+ feet in one season, and then do it again next year, or possibly even twice a year depending where you are. My final conclusion of your article is that it has been very poorly researched, and it sounds like someone talking alot about something they have no clue about.

  2. Michael Floyd

    Dear Seshata,

    My personal apologies if my comment earlier was too harsh. I meant no harm, I was just sad to see and article like this on sensiseeds.com! What I should have said is that this article seems to have been put together in a few hours using Google, and it is refuting a man’s “theory,” developed over 23 years. (He doesn’t claim everything is 100% fact, but he has some great evidence to back up his theory.) Im sure you will understand more about it after his book is released, and who know maybe you will change your mind.
    Just wondering, but do you a background in environmental science?

    1. Seshata - Sensi Seeds

      Dear Michael,

      You seem very stuck on the idea that I’m ‘refuting’ von Hartmann’s claims. I am not, I am merely pointing out that they are unsourced, and as such they are essentially useless when formulating an argument (unless it is designed to be an emotional argument, and not one based on empirical fact). Furthermore, the article does not even solely focus on von Hartmann’s work. I see you have taken no issue with the other websites I have named as being responsible for disseminating unsourced or sensationalist information? Is this because you are not personally affiliated with them, or is it because they are in some way even less credible than von Hartmann? If so, why?
      You state: “I think you are highly disregarding the impact that growing the Tree of Life (Cannabis) would have on this planet. Anyone with a working nose can readily tell that cannabis produces an abundance of monoterpenes. We don’t need a Rocket Surgeon to tell us that one. At what point does one trust science over ones own intuition?”
      Unfortunately, my remit is not to trust my nose or my own intuition, but rather to assess the quality of the existing scientific research and base my conclusions on it. I apologise if this does not yield the results you want, but they are the results I have been led to make following review of the literature. Anything else would be to disregard the evidence and promote ‘intuition’. This would be at best bias, and at worst propaganda; the point at which environmental policy is dictated by ‘intuition’ –someone’s gut feeling!—will be the point that I lose all hope in humanity.
      This is also the reason I immediately feel my gut sinking when I see people referring to cannabis by such quasi-religious terms as the ‘Tree of Life’. Whatever your personal beliefs, there is no place for such nomenclature within the area of empirical research. There is a good reason we attempt to separate religion and spirituality from science and politics—the former are based on emotion, the latter should be based on fact.
      I’m happy to provide a retraction if a source can be provided for the claim that ‘the cannabis plant is exceptional in producing copious amounts of 58 monoterpenes in less time, in more soil and climate conditions, with greater ecological and economic benefit than any other agricultural resource on Earth’. However even in von Hartmann’s subsequent communications, no source is provided.
      Now, I have stated various times throughout the article that cannabis has numerous beneficial properties: ‘Cultivating more cannabis and hemp where appropriate would undoubtedly bring multiple benefits’; ‘With properly-managed techniques, there is no reason that cannabis and hemp should not be planted as part of a sustainable strategy for carbon sequestration’; ‘There are already more than enough good reasons for cannabis to be legalised’. Thus, I’m not sure what basis you have for your assertion that I am ‘highly disregarding the impact that growing the Tree of Life (Cannabis) would have on this planet’. Please, enlighten me.
      Another thing: at no point do I see any reasonable refutation of my core argument, which is that cannabis is being wrongly singled out as a species that will single-handedly end climate change and restore balance to the various diverse global ecosystems that are currently impacted by loss of biodiversity, pollution, habitat loss and so forth. I still stand by this: planting cannabis alone will not solve the world’s environmental, social or economic ills. It may have a part to play, but this part is being overstated by—no doubt well-intentioned—activists seeking to further the cause.

      1. Bruce Michael Dietzen

        One major point was overlooked in this article. Hemp has a huge potential to sequester atmospheric CO2 if we make as many durable goods as possible from this miraculous plant.

  3. Michael Floyd

    Howdy Sesheta,
    The section titled “what’s wrong with this argument” appears to be refuting his work. Also his work is titled “Cannabis vs. Climate Change” and this article is titled “Cannabis and Climate Change.” Coincidence? Who knows? The only other small refutation that I saw was about a possible misrepresentation of carbon sequestration per hectare by some website.
    Personally I’d say it is a sad state of a soul when one trusts science over ones own intuition. That being said I understand your work as a writer would be scrutinized if you wrote solely based on this. As for the Tree of Life, this is the name by which I understand the plant. You may call it whatever you wish as well. I don’t claim to be a scientist or journalist, so my writing surely reflects that. I majored in government, and they claim the right to tell us that we can’t plant seeds, which is our right on earth as humans.

    As for your core argument, I agree that cannabis alone will not save the planet. It will require all organisms on earth working together. The problem with right now is that as a “team” on earth we have our greatest “team player” sitting on the bench due to draconian laws prohibiting humans from growing a plant that can surely help save the planet. It’s time to end the madness and add cannabis an hemp back into the mix so we no longer need to cut our allies the trees. I sure do love me some oxygen. 🙂

    We are on the same team.
    Peace and Love,
    Michael

  4. Paul von Hartmann

    I can’t believe you’re still censoring my comments. Shame on you. In refusing to post my comments, this published disregard for an original hypothesis has degenerated beyond the issue of your journalistic competence.

    Either post my replies or take this opinion down. Holland isn’t a country that has historically appreciated censorship or limited thinking.

    PvH

    1. Dear Paul,

      I am sorry for the delay in publishing your comment. This delay however, has nothing to do with censorship but with the fact that all comments placed on this blog must be put through a validation process in order to avoid spam.
      All the best,

      David

  5. Paul von Hartmann

    “I’m happy to provide a retraction if a source can be provided for the claim that ‘the [C]annabis plant is exceptional in producing copious amounts of 58 monoterpenes in less time, in more soil and climate conditions, with greater ecological and economic benefit than any other agricultural resource on Earth’. However even in von Hartmann’s subsequent communications, no source is provided.”

    ~~~~~~~~~~~~~~~~~

    I am the source of that observation, that premise upon which meaningful change can occur. I take full responsibility for pointing out the obvious and challenge anyone to prove me wrong. It is a conclusion based on decades of empirical personal observation and hands-on experience with growing lots of different types of plants, including plenty of Cannabis.

    Much of what I learned about the terpene characteristics of Cannabis, seventeen years ago, comes from having enjoyed extended personal interviews and conversations with scientists at the Swiss Federal Research station, near Zurich in 1997. My friend Vito Mediavilla with whom I stayed, was a most gracious host and charmingly enthusiastic in sharing his research and insights.

    THE PRODUCTION OF ESSENTIAL HEMP OIL IN SWITZERLAND
    Vito Mediavilla
    Swiss Federal Research Station for Agroecology and Agriculture Reckenholzstrasse 191, CH-8046 Zurich, Switzerland

    As for the growth characteristics of Cannabis, that potentiate hemp as the world’s most abundant, available and complete source of sustainable essential commodities, in less time than any other crop, well , that’s a verifiable statement as well.

    ~~~~~~~~~~~~~~~~~~

    “Unfortunately, my remit is not to trust my nose or my own intuition, but rather to assess the quality of the existing scientific research and base my conclusions on it. … the results I have been led to make [follow] review of the literature. Anything else would be to disregard the evidence and promote ‘intuition’. This would be at best bias, and at worst propaganda; the point at which environmental policy is dictated by ‘intuition’ –someone’s gut feeling!—will be the point that I lose all hope in humanity.”

    ~~~~~~~~~~~~~~~~~~

    The point at which science loses intuitive insight is the point at which science ceases to live beyond so-called “facts.” All scientific inquiry that’s ever been began with warm, wet, passionate human curiosity. The initial spark of inquisitiveness is followed by intuitive reasoning (“an educated guess”) and formulation of scientific theory, based in what is known and what is believed to be known. For you to label broader intuitive science as “bias” and “propaganda” is simply ignorance of the scientific process in which you are apparently not involved.

    That, and the misrepresentation of net carbon sequestration potential make this post an embarrassment to my friends at Sensi Seed, in that it proves you are not qualified to write about Cannabis and Climate Change.

  6. Paul von Hartmann

    “We have found it of paramount importance that in order to progress we must recognize our ignorance and leave room for doubt.

    “Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain.”

    “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.”

    ~ Richard Feynman, Nobel prize-winning American physicist (May 11, 1918 – February 15, 1988)

  7. Paul von Hartmann

    Hi Dave,

    Thank you for posting my most recent comments, though there were others sent previously that didn’t make it through. No worries. I appreciate that you have shared my thoughts with others.

    Blessed rushes,

    Paul

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    Sensi Seeds

    The Sensi Seeds Editorial team has been built throughout our more than 30 years of existence. Our writers and editors include botanists, medical and legal experts as well as renown activists the world over including Lester Grinspoon, Micha Knodt, Robert Connell Clarke, Maurice Veldman, Sebastian Maríncolo, James Burton and Seshata.
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