Talk:Carbon dioxide removal

Condensed the methods section
I've just re-arranged and condensed the methods section. I felt that if the content regarding carbon sequestration is too long here then people will in future continue to add more content about carbon sequestration which then results in double work: we'd have to update it here and also at carbon sequestration. Therefore I think the content about carbon sequestration needs to be brief here, summary style. I've used an excerpt for that. I think even the remaining content about agriculture and biochar ought to be condensed further. CDR is mainly about carbon sequestration and about DACS, right? The details about those can be found in the respective sub-articles and don't need to be repeated here. Summary and overview: yes, details: no.

The content about issues could perhaps require fleshing out, although again the content about issues will be very similar at carbon sequestration and at direct air capture so we need to be careful to be wise about it so that we don't have to maintain and update that issues content on three pages in parallel. EMsmile (talk) 13:08, 7 February 2023 (UTC)

Ocean direct removal
your revert at seems to misunderstand the stage electrolytic desalination is at for carbon removal. The source is not "possible fundamental research", it's the measurements including the economics for earlier work such as, ,  and.

A wider question, why is this article completely devoid of any mention of ocean-based direct carbon removal? It's an active applied field with dozens of pilot projects ongoing. It's more efficient than direct air capture because the mean free path of gases in air aren't as available to reactive surfaces as liquid seawater. And of course the CO2 in air is in equilibrium with carbonate in seawater, so it's the same end result.

Why doesn't this article mention direct ocean removal at all? Can you think of a better example of it to include? Ocean alkalinity enhancement isn't appropriate given its terrible economics. Sandizer (talk) 15:04, 15 February 2023 (UTC)
 * Hi User:Sandizer, this article is a high level overview article that summarises the relevant sub-articles but should not go into much detail. That detail is in the sub-articles. E.g. all the content about oceans is in carbon sequestration. This section heading gives the summary and points the reader to the right sub-article: Carbon sequestration on land and in the ocean . I hope this makes it fairly clear to the reader (although it wasn't clear to you, so maybe it needs to be done differently). EMsmile (talk) 16:56, 15 February 2023 (UTC)
 * For that paper that you had added, I can take a second look but if anything it might fit better at carbon sequestration than here. The electrolysis option is also mentioned here at ocean acidification: https://en.wikipedia.org/wiki/Ocean_acidification#Carbon_removal_technologies_which_add_alkalinity
 * For easier reference I copy below your edit that I had reverted: EMsmile (talk) 16:56, 15 February 2023 (UTC):
 * @Sandizer I had not heard of ocean direct removal before so I would certainly be interested to read about it in Wikipedia. Not sure where it should be put but I agree with the general principle that stuff should be put in a sub-article first and then if it becomes more important added to the main article Chidgk1 (talk) 08:36, 1 March 2023 (UTC)

Electrodialytic ocean carbon removal and desalination: Salt and carbonate can be simultaneously removed from seawater via economical electrodialysis for simultaneous desalination and carbon removal.
 * Direct ocean removal, meaning the extraction of carbonate (carbonic acid) from seawater, is different than ocean sequestration, which is depositing carbon solids on the seabed floor. Should an article on removal have anything on sequestration? Also, that section at Ocean acidification should probably be in this article instead. Chapter 8 ("Electrochemical Engineering Approaches, pp. 209-238) of its source, does mention that combining with desalination significantly reduces the cost. Sandizer  (talk) 21:57, 15 February 2023 (UTC)
 * Ocean sequestration is not always simply "depositing carbon solids on the seabed floor". The full range of ocean sequestration techniques is shown here: carbon sequestration. Regarding your question: "Should an article on removal have anything on sequestration?": yes of course it should. See this sentence in the lead: "CDR methods includes carbon sequestration methods (for example afforestation, agricultural practices that sequester carbon in soils (carbon farming), enhanced weathering, etc.) and direct air capture when combined with storage." I think that section at Ocean acidification fits well there but it should also be linked from carbon sequestration if that is not the case yet. I don't think that it needs to be in this high level overview article as well, apart from perhaps a brief link. EMsmile (talk) 09:48, 16 February 2023 (UTC)
 * Pinging User:ASRASR for another opinion as they are currently working on the carbon sequestration article. EMsmile (talk) 09:49, 16 February 2023 (UTC)
 * Another question for both of you: Should plastic lumber (which can displace wood timber resulting in afforestation, and is thus doubly carbon negative when produced from removed carbon) be included here? See  Sandizer  (talk) 04:30, 17 February 2023 (UTC)
 * another question, should we include a description of Captura's process? Please see https://capturacorp.com/ and this video. Note they distinguish their process from ocean alkalinity enhancement, although it technically is. You can see around 14:30 in the video that they use an electrodialysis process, but they don't desalinate. So even though they may be furthest along commercially at present, it's still going to be more expensive than dual use desalination. They do discuss partnering with desalination plants, however, so I can't imagine they don't mean in a synergistic way. Sandizer  (talk) 09:39, 19 February 2023 (UTC)

Well it's been a week, so I'm planning to replace the Mustafa passage and add Captura unless anyone objects. Sandizer (talk) 00:57, 27 February 2023 (UTC)
 * It's unclear to me what you are suggesting here but I still think this is not the right place for such detailed content. This is a high level article. Go more for the sub-articles and use reliable sources, preferably secondary sources. Please see here for guidance: https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Climate_change/Style_guide EMsmile (talk) 14:38, 27 February 2023 (UTC)
 * Well let me ask you this: the carbon from any method of removal can be either sequestered or utilized, right? If this article has direct air capture, why shouldn't it also have the analogous process of direct ocean capture? They are the same thing just from different media, and ocean capture is the more energy efficient of the two, and by far the most economical when combined with desalination. Sandizer  (talk) 10:09, 28 February 2023 (UTC)
 * It's still not clear to me what you are getting at. You are talking about a specific technology that is at its basic research stage, right? Has it been included yet in the IPCC Sixth Assessment Report Working Group III on mitigation? I am not saying it can't be included somewhere in Wikipedia but we have to observe WP:DUE for this high level article as it could otherwise become a listing of all sorts of new, emerging technologies. Could you put in your sandbox exactly what sentences and references you are proposing, and then we can review that? Please keep in mind the need for reliable secondary sources as per here: https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Climate_change/Style_guide. I am also pinging some other people from WikiProject Climate Change for their inputs (I think this article on carbon dioxide removal is actually pretty important): User:Femke, User:Clayoquot, User:RCraig09, User:Chidgk1. EMsmile (talk) 10:49, 28 February 2023 (UTC)


 * The weight that article gives to each CDR technique should reflect the prominence of that technique in high-quality general sources such as IPCC reports. Can anyone point to a high-quality general source that mentions direct ocean removal? Clayoquot (talk &#124; contribs) 15:33, 28 February 2023 (UTC)
 * https://www.ipcc.ch/srocc/chapter/technical-summary/ says “Ocean-based carbon dioxide removal at the global scale has potentially large negative ecosystem consequences.” so I thought there ought to be more details as that is a summary but I cannot find where (if anywhere) the IPCC has written more detail. Also I don'T know if they are talking about direct removal. Are they implying that the CO2 flow towards the removal points would be too slow so the acidity near those removal points would fall below the pre-industrial level? Or if not what are the potential problems? They should certainly be written somewhere in Wikipedia but I don't know if this is about direct removal Chidgk1 (talk) 08:55, 1 March 2023 (UTC)
 * ARPA-e classify it as an “exploratory topic” https://arpa-e.energy.gov/technologies/exploratory-topics/direct-ocean-capture
 * Section 4.2 of https://files.wri.org/d8/s3fs-public/2022-11/towards-responsible-and-informed-ocean-based-carbon-dioxide-removal.pdf explains it in terms I can more or less understand. The point I take away is that we need to get ahead of the game and build a lot more electrolyser factories here in Turkey! Chidgk1 (talk) 09:19, 1 March 2023 (UTC)

For reference, the section under discussion is "Electrodialytic ocean carbon removal and desalination" here. Thanks Chidgk1 for the sleuthing! I've also tried to find a mention of direct ocean removal in the IPCC's SROCC and AR6 reports and couldn't, although I could have missed something. The WRI report is a good secondary source that does cover it.

There is a lot of research happening in CDR. I agree with EMSmile that we can't cover every single thing under investigation; on the other hand mentioning prominent areas of research is sometimes due weight. Is this a prominent area of research? Are there areas of research that are more prominent that we don't mention? Clayoquot (talk &#124; contribs) 17:18, 31 March 2023 (UTC)


 * yes, it is a prominent area of research. I don't have any way of knowing whether there are other more prominent areas not included. Where do you see it in the WRI report? https://www.wri.org/research/state-climate-action-2022 omits electrodialytic methods. But those seawater methods are always going to be more efficient, when combined with other seawater processing systems such as desalination, because of the nature of aqueous phase chemistry availability to catalysis much more often than direct air capture, because the mean free path of gasses keeps them away from removal opportunities.
 * I just feel that ocean capture needs to be described alongside air capture, especially for that reason. They are directly analogous processes. Mentioning air capture without mentioning ocean capture is like discussing automobile transportation without discussing carpooling. Sandizer  (talk) 00:35, 11 April 2023 (UTC)
 * Interesting. I hope you're right. In the WRI report, it's Section 4.2 is devoted to "Electrochemical techniques". It references a 2021 NASEM report which Wikipedia would consider an excellent source. I also recently noticed that ocean direct removal gets a mention on p. 1273 of the IPCC AR6 WGIII report. A best practice is to write from secondary sources rather than from original research papers. If you can add a sentence citing any of these three reports I think it would be fine.
 * I see you also asked a question about plastic lumber that nobody has answered. yet, so I'll give it a go. I cannot see how the use of plastic would promote afforestation. Regarding the source you proposed, this is a student research project so it is definitely not suitable. Cheers, Clayoquot (talk &#124; contribs) 05:27, 11 April 2023 (UTC)
 * Regarding your point that the article doesn't mention any ocean-based methods at all, we used to have a section on ocean fertilisation but it was removed. Ocean alkalinity enhancement also disappeared at some point. Both methods should be re-added. We do not need a huge section for each method but we need something. Clayoquot (talk &#124; contribs) 05:43, 11 April 2023 (UTC)
 * Would you be okay if we mentioned ocean fertilization, alkalinity enhancement, and electrodialysis all in about as much text as we have here for direct air capture currently? We don't need to go into detail, but there are good literature reviews for all three, including by Mustafa et al. to which their economic analysis in combination with desalination is a follow-on. That more specific WRI report I missed (thank you!) is very helpful and should be in the article too, but it omits those more efficient, less expensive, and likely higher volume desalination dual-use opportunities. As for plastic lumber, I know I have a better source for sequestration in building materials which displaces demand for wood timber. I am staring at a graph I clipped from it and trying to remember where it came from. (I know where it is: on a laptop I destroyed by spilling coffee on it, and for which I do have a good backup, but it will take me some more time to find it on a different OS....) Sandizer  (talk) 16:53, 13 April 2023 (UTC)

Explaining exactly the terminology regarding negative emissions
Regarding this edit that I made a while ago, User:Clayoquot brought this to my attention: "I want to make sure you understand that the definition of CDR is not the definition of "net negative greenhouse gas emissions", "net zero CO2 emissions" or "net zero greenhouse gas emissions". I fixed the error in Carbon dioxide removal but if you've carried this misunderstanding to other articles, they will also need to be fixed." Don't worry, I did not have the impression that it's the same thing. However, I was trying to clarify some content on the existing page and might not have done a good job got it wrong, I am very sorry! But I think it's still not overly clear in the current version.

Looking at the glossary of the AR 6 WG 1 report it says: Negative greenhouse gas emissions: Removal of greenhouse gases (GHGs) from the atmosphere by deliberate human activities, that is, in addition to the removal that would occur via natural carbon cycle or atmospheric chemistry processes. When I compare that with the IPCC definition for CDR (CDR = Carbon dioxide removal (CDR) Anthropogenic activities removing carbon dioxide (CO2) from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products.) I conclude that CDR equals "negative CO2 emissions" - right? (but not "net negative CO2 emissions"). that's what is also says in the lead currently. Therefore, my suggestion would be to add that back into the definitions sections and to say: "The definition for negative CO2 removal emissions is the same as the one for carbon dioxide removal". Furthermore, this sentence is not very clear: "The U.S.-based National Academies of Sciences, Engineering, and Medicine uses the term "negative emissions technology" with a similar definition.". I would say: "The term negative emissions technology is commonly used in the the same way as the term for carbon dioxide removal emissions." (mind you, when they speak of emissions, are they thinking of all GHGs or only CO2?). EMsmile (talk) 12:34, 29 March 2023 (UTC)
 * I am sorry, I meant to say "negative CO2 emissions" of course, not "negative CO2 removal". EMsmile (talk) 17:20, 29 March 2023 (UTC)
 * Good point that it makes sense to describe the term "negative emissions technology" in a way that isn't organization-specific. I've made some adjustments. Clayoquot (talk &#124; contribs) 21:58, 29 March 2023 (UTC)
 * Thanks, the definition section is looking much better now. I have two small queries:
 * Do we really need this sentence in the definition section? It seems to go beyond the issue of "definition": When CDR is framed as a form of climate engineering, people tend to view it as intrinsically risky
 * Could we make it clearer in the definition section or in the one that follows what CDR has to do with carbon sequestration? We kind of mention it in the first sentence of the lead but not in the main text. It was something that confused me when I first started to look into these terms. EMsmile (talk) 12:35, 30 March 2023 (UTC)
 * Thanks, I moved the sentence on climate engineering. Regarding clarifying the relationship between CDR and carbon sequestration, this needs to be done throughout the article. Carbon sequestration does not have to involve humans. For a process to count as CDR, the process has to be caused by human activity. Currently the examples and conceptual explanations in the article are a mixture of 1) actual CDR and 2) things that people often confuse with CDR but are not CDR. Clayoquot (talk &#124; contribs) 14:28, 30 March 2023 (UTC)

Magnesium silicate/oxide in cement
I am removing the section on Magnesium silicate/oxide in cement as I don't believe it is due weight to mention it. The cited source says its net GGR is not fully understood and IPCC AR6 WGIII agrees, saying it "could" be carbon-negative (p. 1191). Here's the entirety of what AR6 WGIII says: "there have been pilot projects with magnesium-oxide-based cements, which could be negative emissions." Here's what I will remove:


 * Magnesium silicate/oxide in cement
 * The replacement of carbonate in cement allows for the potential absorption of carbon dioxide over concrete lifecycle. However, lifecycle amounts are not yet fully understood.

Clayoquot (talk &#124; contribs) 05:52, 15 April 2023 (UTC)

Clarification about methods section and past mistakes/confusion by me
I am copying here something from my talk page that User:Clayoquot had put together there. I think it's useful to have it here to show where I went wrong (during some editing work in Feb and March 2023) and to help others as well if they have similar confusion that I had:

Also from Clayoquot on my talk page: "Your statement above emphasizes the superficial and low-risk improvements that you make to articles. I included the examples above to illustrate that you’re also making substantive changes to highly visible parts of articles and sometimes getting elementary facts completely wrong. Inclusion of BECCs as a CDR method is so basic that one-page overviews of the topic cover it.." EMsmile (talk) 07:59, 12 May 2023 (UTC)


 * Also copied from my talk page a follow-up comment by User:FeydHuxtable on 18 April 2023 which I felt was interesting and worth re-iterating here: "Since Kyoto, there's been over 60 different major attempts to set global standards for carbon trading, several of them using conflicting definitions and terminology. There's been a near 1$billion /year operation to spread misinformation, resulting in many confusing sources. Granted, CDR itself is fairly well defined. Still, while agreeing with how Clayoquot has resolved this, it's quite legit to have different views as to whether something like sequestration is a broad class of CDR method, versus a follow on activity that (almost always) occurs regardless of which particular method was used. This relates to the two conflicting ways the term GHG 'sink' is used in the literature. I see there was some confusion about this over on the climate project page, I may post over there to clarify." (see here the discussion about carbon sinks) EMsmile (talk) 08:03, 12 May 2023 (UTC)

Proposal to add 2x2 image collage to the lead
I think this article would benefit from a 2x2 image collage for the lead, similar to the ones at climate change adaptation and climate change mitigation. It could show nicely the range of CDR options, rather than just one image of a tree planting project. My suggestion would be 1 image of each for: I would not be in favour of having a picture with ocean fertilisation or ocean alkalinity enhancement as I regard those as experimental and with a low likelihood of ever being applied at full scale. In any case, we would only have space for 4 images so would have to make a selection, and might as well pick those that are currently most promising with some due weight consideration (?). EMsmile (talk) 08:09, 12 May 2023 (UTC)
 * 1) Afforestation or reforestation
 * 2) wetland restoration or mangrove protection (coastal vegetated zones / blue carbon)
 * 3) bioenergy with carbon capture and storage (BECCS)
 * 4) direct air capture when combined with storage


 * I still think this would be useful and important. Any reactions from those watching this page? The tree planting image in the lead makes it so simplistic. EMsmile (talk) 15:40, 4 July 2024 (UTC)
 * Sounds good to me :) Clayoquot (talk &#124; contribs) 16:46, 4 July 2024 (UTC)

Add thermal decomposition of Bio-Methane
Thermal decomposition of methane results in Hydrogen gas and carbon solid and should be included in this article when combined with bio sources of methane by anaerobic digestion. 159.196.168.197 (talk) 05:52, 13 June 2023 (UTC)


 * Do you have a reliable source for that information please? Chidgk1 (talk) 19:21, 21 May 2024 (UTC)

Merge proposal
I propose merging Carbon sequestration into Carbon dioxide removal because “carbon removal” seems to be roughly how people refer to the whole thing nowadays, for example https://climate.ec.europa.eu/eu-action/certification-permanent-carbon-removals-carbon-farming-and-carbon-storage-products/permanent-carbon-removals_en

As well as making it easier for us to remove duplication and so keep content up to date I think the word “sequestration” is not obvious to lay people so this merge should make it easier for them to find the info they are looking for. Chidgk1 (talk) 13:30, 26 May 2024 (UTC)


 * Oppose. "Carbon removal" and "Carbon dioxide removal" refer to removal of CO2 from the atmosphere that is  caused by human activitiy. Carbon sequestration is a broader concept that includes both anthropogenic and non-anthropogenic processes, with the vast majority of it being non-anthropogenic. If the two articles currently have a lot of overlap it's probably because the Carbon sequestration article underweights these spontaneous non-anthropogenic processes. Clayoquot (talk &#124; contribs) 23:22, 26 May 2024 (UTC)
 * @Clayoquot Hmm so maybe I should formally propose a merge of carbon sequestration with Carbon sink instead as the first sentence of that article says “ A carbon sink is a natural or artificial process that "removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". which sounds pretty much the same as your definition of carbon sequestration? Chidgk1 (talk) 08:14, 27 May 2024 (UTC)
 * They only sound the same if one focusses on the fact that both include natural & artificial processes. Generally, "Carbon sequestration" is used in the literature to specifically discuss carbon (not non-CO2 GHG) and storage (as opposed to removing a GHG by transformative process). "Carbon sink" is a much broader concept. Key aspects were easier to understand back in the day. Back in the early 90s, IPCC defined sinks without the carbon prefix. These days though, "carbon sink" is used in a way that's inclusive of other GHGs and even precursors as per the definition you quoted – partly as for most seriously engaged with CO2 mitigation, the concept of Carbon dioxide equivalence (CO2e or CO2 -eq) is always at the back of their mind.
 * Carbon sinks include for example CH4 > CO2 + H2O, a process that releases into the atmosphere, so in a sense the opposite of carbon sequestration, but resulting in a considerable fall in overall  Global warming potential. That said, on a deeper level all types of sinks are complementary with sequestration (The single most important meaning of sink in contemporary science = opposite to source).  FeydHuxtable (talk) 10:53, 27 May 2024 (UTC)
 * Yes I think a separate formal merge proposal is the way to go if you're so inclined. Clayoquot (talk &#124; contribs) 15:13, 27 May 2024 (UTC)
 * Hi User:Chidgk1, where do we stand with this? I think you should withdraw your merger proposal with Carbon dioxide removal? EMsmile (talk) 15:25, 14 June 2024 (UTC)