The forgotten carbon sinks – policymakers are overlooking solutions to the climate crisis

A week ago, the BBC published an article about rapidly disappearing Posidonia seagrass in the Mediterranean. In a time in which news outlets seem to report every other week about another species becoming endangered or extinct, the news of the Posidonia seagrass might seem like just another little reminder that the 6th mass extinction might be on its way but not much more than that. However, the article reveals some shocking news: a hectare of Posidonia seagrass can capture 15 times more CO2 than a hectare of the Amazon forest.

Healthy Posidonia seagrass (Posidonia Oceanica).
Healthy Posidonia seagrass (Posidonia Oceanica).

Why are leaders and policymakers barely talking about this carbon sink when discussing solutions for the climate crisis? It seems like they are hung up on technical solutions. These Prometheans believe that the technological abilities of humans are endless and that they can use these technologies to advance humanity and alter the environment if needed. They want to decrease CO2 emissions by technological solutions such as setting new efficiency standards for refrigerators, subsidising electric car use and replacing fossil fuels with nuclear energy. However, with countries failing to reduce their CO2 emissions and governments failing to come up and comply with strong treaties and conventions on CO2 reductions, policymakers and scientist also try to find solutions elsewhere. But it is not the natural world they are looking into.

One field that has been receiving more and more attention is geoengineering, the ultimate Promethean solution. The idea seems simple: if we cannot reduce our emissions, we have to find a way to minimise the impact of the emissions on earth. One form of geoengineering is carbon dioxide removal from the atmosphere. By removing carbon from the atmosphere, the carbon molecules cannot exert their greenhouse gas effect and no warming will occur. If enough carbon is removed, the CO2 concentrations in the atmosphere will lower, and global warming will decline. However, carbon removal has some disadvantages. It is very costly, and most countries won’t be too eager to pay for it. Additionally, the carbon has to be stored somewhere, and no one wants to live on a CO2 field, which could kill you if it leaks. Due to carbon capture and storage’s disadvantages, it has not been used on a large scale, and many debates arise on whether it can be used as a solution for the climate crisis.

So, while this technical carbon sink does not seem like an ideal solution, the many natural carbon sinks that already exist seem to be forgotten by policymakers.

When policymakers do address natural carbon sinks, trees seem the only ones they know. Many governments and policymakers call for reforestation and even all Dutch parties but one vouch for it. However, other leaders, like the Brazilian president Bolsonaro, do not see the added value and (illegal) logging still continues. While the rate of deforestation has gone down over the last years, overall, the number of forest areas still declines every year.

Other natural carbon sinks, such as Posidonia seagrass, receive less attention. While the EU has some protected areas for the seagrass, the hectares of seagrass have decreased and are still being damaged today. Especially anchors can severely damage seagrass. For a single anchor, it can take 1000 years for the seagrass to be fully restored. However, it is often still allowed to anchor in the protected areas, and if regulations are present, they are often ignored. With increasing temperatures, the remaining seagrass will have an even harder time surviving as it cannot withstand temperatures above 28 °C. While policymakers are focused on technical carbon sinks, this carbon sink is overlooked and slowly lost.

Another example of an carbon sink that deserves recognition is mangroves. Mangroves are a habitat for many organisms and can take up as an ecosystem on average 956 t C per hectare, which is almost four times more than the 241 t C per hectare uptake of rain forests. Mangrove ecosystems also emit CO2, for example, through respiration. Mangroves are a net carbon sink and worldwide take up 90 Tg C per year, which is as much carbon as some small countries emit. With increasing temperatures, mangroves could spread to temperate areas, which could increase their carbon uptake. However, some researchers expect that in colder climates, the ecosystem’s uptake could be lower. While mangroves are valuable as they are a carbon sink, protect coastlines and prevent erosion, they are, unfortunately, often cut down for their wood or to make room for agriculture and aquaculture. It is estimated that 30-50% of mangroves have been lost over the last 50 years. Policymakers are thus losing a valuable solution for the climate crisis.

Forests by the Sea: Mangroves and why they are threatened ...
Mangroves are a habitat for many species above and underwater.

These natural carbon sinks are not only being forgotten by policymakers, but they are also being destroyed. While policymakers praise new technological fixes, the solutions that are already out there are shifted aside. Ecomodernist take this to the next level. They do not only see technology as the holy grail, but they think humanity should be based on it. Their solution to the climate crisis is for humans to live in densely populated cities where food is produced with highly efficient agricultural practices that barely need any land. Humans will only use a bit of the earth surface, and nature can take over the rest. For them, the dependence on ecosystem services and resources is the core cause of the need for nature conservation. Ecomodernist even go as far as to say:

“People may choose to have some services — like water purification and flood protection — provided for by natural systems, such as forested watersheds, reefs, marshes, and wetlands, even if those natural systems are more expensive than simply building water treatment plants, seawalls, and levees.” (p.27)

For me, this quote shows how Prometheans and ecomodernist are blinded by their faith in technology. Why would we need to develop technologies if what we are creating is already provided to us by nature? Besides, technology also has some downsides that they seem to overlook. It might not be able to solve all problems and often comes at a cost. Additionally, the more advanced the technology becomes, the fewer people can understand it and decide on its use. The Prometheans will find themselves in a vicious circle by erasing the negative side-effects of existing technology with new and more advanced technology.

While we might find ourselves unable to solve the climate crisis with natural solutions alone, policymakers should be aware of the natural solutions present and strive to protect them before it is too late.

19 thoughts on “The forgotten carbon sinks – policymakers are overlooking solutions to the climate crisis

  1. This is a very informative and compelling blogpost! Although I was aware of the importance of seagrass and mangroves within their ecosystems, I did not know that they could capture so much CO2, even more than trees. In this sense, it would be interesting to see if there is any possibility of “reforesting” -for a lack of better word- mangroves and seagrass. I imagine that this is harder than planting trees, but at least we should definitely enforce stricter rules that protect these natural carbon sinks. I think that an interesting strategy would be that richer countries invest in the protection and recovery of these highly efficient carbon sinks, which tend to be located in developing countries such as Brazil, Indonesia, Pakistan and Mexico.


  2. Thank you indeed for the interesting blogpost! Interestingly, when I was searching for inspiration for my blogpost, I stumbled on this article from the Guardian: which not only touches upon the fact that seagrass stores carbon faster than a rainforest, but also reveals that it has tremendous potential as nutrition: it contains 50% more protein than rice per grain for example. This is one the reasons why for the Seri, an indigenous community from Sonora, Mexico,this sea grass has been an important part of their diet for decades. I think this also nicely ties in with the general idea of your post, namely that we (especially in the west) are so busy developing technological ‘hypes’, that we are disregarding nature’s solutions and indigenous knowledge about these solutions.


  3. I never knew about the potential of seagrass; it was quite surprising to me that such a tiny plant could store so much CO2. I also agree with you that we should look at nature-based solutions first, however I wonder how feasible planting seagrass and mangroves is on a scale large enough to make real impact on current greenhouse gas concentrations. Importantly, will widespread planting of seagrass and mangroves not negatively impact biodiversity due to “monoculture” as so to speak? I imagine that mangroves could form the base for a whole ecosystem, but how would that work for seagrass?


  4. Hi, thanks for bringing this up! It is definitely important to switch from a focus on technological carbon storage to natural carbon sinks.

    I do want to point out that I feel that your account of leaders and policymakers might be a bit one-sided. Even though I do believe a quite some governmental action is not radical enough, I wouldn’t say all policymakers are ecomodernists. The true believe in decoupling and a technofix are definitely not shared by everyone.

    Another thing I would like to mention is that by shifting from carbon capture and storage to increasing natural sinks, we are still not addressing the root cause of the issues. Yes, the fact that there is too much carbon in the atmosphere is a problem. However, storing carbon is only part of the solution. There is a need to stop the emission of carbon to the atmosphere in addition to increasing natural carbon sinks. So, address the system that is both enabling these carbon emissions and at the same time trying to prevent real change by promoting technofixes.


  5. Thank you for writing this blog post!
    It was very informative and interesting. I did not know seagrass and mangroves can capture so much CO2.
    A friend of mine from Mexico has once told me that mangroves are important because they protect them from floods or high waves. The fact that not only capturing CO2 but also being able to act as flood protection and water purification reminded me of Eco-DRR (disaster risk reduction), a sustainable management of ecosystem to reduce disaster risk. I think this is a great example of “killing two (or more) birds with one stone” that technology cannot achieve.


  6. Thanks for the post! An example of important carbon sinks closer to home: peatlands. They can store a huge amount of carbon. In the Netherlands, however, we artificially make the water levels lower so that cows can grass on it. Because of this, carbon oxidates and gets emitted as CO2. The solution: make the wetlands wet again!


  7. Thank you for bringing up Posidonia meadows in the Mediterranean (or Blue Carbon in general)! Seagrass is indeed incredible for storing carbon but, for example in Greece, it’s terrible to see that marine protected areas are hardly reinforced and meadows are destroyed when boats are anchoring in bays. So there is a lot of work to do in the Mediterranean to protect Posidonia. The organization I am doing my internship with is collecting seagrass fragments to replant them which is great, although replanting methodologies are still being trialled (and it takes a couple of year for the replanted seagrass patches to capture carbon at similar rates as older meadows). But I know that, for example, the University of Plymouth is working on a large seagrass/ blue carbon project in the UK which is great to see.


  8. Hi Karla,
    Thank you for your response. It would be great if ‘reforesting’ programmes would be set up. I agree with you that it would be interesting to have rich countries fund the reforestation in ‘developing’ countries. This way, the rich countries which (indirectly) cause the ‘deforestation’ would pay the price for their consumer behaviour. I think it is fair that the richer countries who mainly caused climate change also pay for the solutions. How do you feel about the intergenerational difference between the generations that caused climate change and the generations that have to pay for the solutions? Our generation will have to pay for the reforestation, but our generation is not the only generation that caused it.


  9. Thank you for your response. Interesting article! I definitely think we miss a lot of valuable information when we do not involve locals.
    The article got me thinking. If the seagrass absorbs 10% of the ocean’s carbon and we can eat it, could it be used in the same way as biomass for bioenergy? If seagrass could be grown (like biomass) and then eaten (like bioenergy consumes biomass), and the seagrass would be planted again, slowly, we would capture more and more carbon from the oceans. The oceans then can absorb more carbon from the atmosphere, which can decrease global warming. I don’t know if humans would exhale more carbon if we consume more carbon, so that might counteract the effect.
    The article also made me realize that I eat (although not often) products that grow in mangroves. Glasswort (Dutch: zeekraal) can be eaten and grows in the Netherlands on beaches or dunes. In other parts of the world, it grows in mangroves! Another reason to protect our mangroves 🙂


  10. Yes peatlands are definitely an important carbon sink! A post was already written about peatlands (by Yvonne on 14-04-2020), so I did not talk about them in my post. Unfortunately, currently with the way peatlands are treated, they are more of a carbon source than sink, so we should definitely make them wet again!


  11. Thank you for your reply. Yes, mangroves have a lot of very valuable ecosystem services! They also prevent the coast from erosion! Seagrass also protects the coastlines from erosion and serves as a habitat for many species. Some fish also use seagrass as a breeding ground. So enough reasons to protect them for sure!


  12. Nice to hear that projects are in place already! Are any of the methodologies promising?


  13. Thank you for your response. You are right that not all leaders and policymakers are ecomodernist. I do think that technological fixes do get a lot of attention, but that might also be because people are more interested in reading an article about an exciting new technology than an article about a new tree planted.
    Natural sinks definitely do not address the root cause of climate change, so additional solutions are needed. However, while emissions are not decreasing enough yet, it might be needed to invest in solutions that mask the ‘symptoms’ of climate change. Natural carbon sinks can be a solution for that.


  14. Thank you for bringing up the point of monoculture! We should certainly be wary of that. I do think that restoring seagrass and mangroves to their original extent, would not be problematic. However, extending them even more, we should definitely keep in mind that the solution to climate change does not do more harm to biodiversity than climate change itself does.
    Seagrass are an important habitat for quite some species and some species even use seagrass as breeding grounds. Thus, it could also improve biodiversity, since some species would be lost if seagrass disappears.


  15. Oh Gigi, thank you for speaking about ‘good old’ Posidonia oceanica and putting a focus on nature-based solutions. As well as seagrasses and mangrove’s incredible potential to capture carbon, I think learning about them can get us over this tree frenzy and become aware of the complexities of carbon sinks and nature preservation in general. Lastly, hopefully looking at the diversity of carbon sinks ad their indefinite co-benefits provided by them can teach us that nature isn’t a number but a whole system of life and services we utterly depend on.

    Liked by 1 person

  16. Oops, I am sorry, I got confused!!! CarECS is the author of this piece (not sure exactly who that is in our class, but my apologies!!!) Thanks for writing about Posidonia 😀


  17. Thanks for the enlightening post, Caridad! I was wondering though, how exactly do you see this pan out in real life? Would you just want the grass to be restored as much as possible based on historical extents, or would you like to see types of ‘agricultural’ fields? Both would have their disadvantages, as the first might not be effective enough and the second might be harmful to biodiversity (as Iris also pointed out). I also feel like the concept of carbon sinks can be dangerous in itself. As Rosalie rightfully mentioned, it might deflect attention from what really needs to be done: to address the issue at its root, to reduce emissions and fix our relationship with the planet. In a way, I think that seeing reforestation (either with seagrass, mangroves or other trees) is a form of Promethean thinking, because it is based on the belief that we can manipulate and control nature to such an extent that allows us to continue our unsustainable consumption patterns. It still has humans and their needs at the center, rather than the planet and all life on it as a whole. Nevertheless, I understand the importance of such carbon sinks, and do think that they can be helpful, although to a certain extent.


  18. Thank you for your comment. I agree that restoring the natural sinks does not address the root of the problem. However, the last COPs showed that even though there is a lot of momentum right now to solve the climate crisis, politicians can still not decide on regulations that will significantly decrease emissions and thus global warming. So, at this point in time, I would say we don’t have the luxury anymore to only focus on emitting less as there is not enough time anymore. Even if reforestation can bring CO2 levels down, we will still need to bring our CO2 emissions down, since we cannot endlessly plant more forests. Therefore, I don’t think attention to reforestation will deflect the attention from the root issues completely.
    Regarding the Promothean thinking, I understand where you come from, but I don’t completely agree with you. I personally think we should stop our unsustainable consumption patterns AND reforest. For me, reforestation is a way to slow down global warming while restoring nature humans destroyed in the first place.
    You say that it has humans and their needs at the center, rather than the planet and all life on it as a whole. I think we might not agree on why we want to slow down global warming. I personally want to slow down global warming, because I don’t want species to go extinct and ecosystems to collapse. The human race will die out eventually anyway, so for me, the reason why I want to combat the climate crisis is to minimise the negative effect humans have on nature. Nature has no voice and the dying corals cannot fight back. For them to survive, humans have to slow down (or halt) global warming. So when I propose that we can use natural carbon sinks, that is because I want mangroves and seagrass to be restored to what they were already before humans destroyed them and I want to minimise the impact humans emissions have on nature. For me, that is having the planet and all life on it at the center.
    Therefore, I would also like to see mangroves and seagrass to be restored to their original extent and not necessarily into agricultural fields. Only if agricultural fields would mask the effects of CO2 emissions so well that the net benefit for the planet is positive than we could consider making them into agricultural fields.


  19. Thank you for this very interesting blog! I wanted to reply to the comment made by Nicky. You wrote “In a way, I think that seeing reforestation (either with seagrass, mangroves or other trees) is a form of Promethean thinking, because it is based on the belief that we can manipulate and control nature to such an extent that allows us to continue our unsustainable consumption patterns. It still has humans and their needs at the center, rather than the planet and all life on it as a whole.” I do not fully agree with this statement. My thoughts are more in line with what CarECS wrote in her reply to this, in the sense that I would personally want to restore seagrass, mangroves and other trees that were historically present, not only because of their ability to store carbon and thus help fight climate change, but because of the fact that we humans destroyed them and thus we humans have the responsibility to restore them. To me personally, the biodiversity these areas provide is at least as important as the carbon capture they elicit. I have noticed often throughout our course that we talk about climate and sustainability, but very regularly leave out the biodiversity aspect. I think this might be another example of that.


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