CDR in the new UNEP Gap Report

[Greg Rau]

https://wedocs.unep.org/handle/20.500.11822/48854;jsessionid=E3A6081B39845062B365E6F1B1324EF9

From the above, new UNEP 2025 Gap Report (re CDR): 
“The  risks  and  uncertainties  related  to  the  achievement  of  the gigaton levels of CDR that would be required later in this century were also stipulated in the 2023 edition of the Emissions Gap Report (UNEP 2023, chapter 7). Methods that deliver CDR are associated with major technological, economic  and  sustainability  challenges,  including  high  energy and water demands, land-use competition, significant costs and technological uncertainties (Fuhrmanet al. 2021; Lane et al. 2021; Meckling and Biber 2021; Rosa et al. 2020; Smith et  al. 2016; Wei et  al. 2021).  Increased  reliance  on  conventional land-based CDR is risky due to issues of land  competition,  protection  of  Indigenous  and  traditional  communities’  land  tenure  and  rights,  and  sustainability,  biodiversity  and  permanence  risks  of  forest-based  CO2 removal, including from forest fires and other disturbances. Scaling and expanding novel CDR methods with geological storage requires time and significant policy effort (Nemet et al. 2023; UNEP 2023). Novel CDR methods are generally at  an  early  stage  of  development  and  are  associated  with  different types of risks, including that the technical, economic and political requirements for large-scale deployment may not  materialize  in  time.  Furthermore, public  acceptance  is  still uncertain, particularly for approaches involving carbon capture  and  storage,  or  the  open  ocean.  These risks can  negatively affect the prospects for scale - up, despite technical potential. Furthermore, overreliance on CDR risks delaying the broader energy transition and decarbonization (Ampah et al. 2024).”

“The  risks  and  uncertainties  related  to  the  achievement  of  the gigaton levels of CDR that would be required later in this century were also stipulated in the 2023 edition of the Emissions Gap Report (UNEP 2023, chapter 7). Methods that deliver CDR are associated with major technological, economic  and  sustainability  challenges,  including  high  energy and water demands, land-use competition, significant costs and technological uncertainties (Fuhrmanet al. 2021; Lane et al. 2021; Meckling and Biber 2021; Rosa et al. 2020; Smith et  al. 2016; Wei et  al. 2021).  Increased  reliance  on  conventional land-based CDR is risky due to issues of land  competition,  protection  of  Indigenous  and  traditional  communities’  land  tenure  and  rights,  and  sustainability,  biodiversity  and  permanence  risks  of  forest-based  CO2 removal, including from forest fires and other disturbances. Scaling and expanding novel CDR methods with geological storage requires time and significant policy effort (Nemet et al. 2023; UNEP 2023). Novel CDR methods are generally at  an  early  stage  of  development  and  are  associated  with  different types of risks, including that the technical, economic and political requirements for large-scale deployment may not  materialize  in  time.  Furthermore, public  acceptance  is  still uncertain, particularly for approaches involving carbon capture  and  storage,  or  the  open  ocean.  These risks can  negatively affect the prospects for scale - up, despite technical potential. Furthermore, overreliance on CDR risks delaying the broader energy transition and decarbonization (Ampah et al. 2024).”

 

My concerns:

1)"gigaton levels of CDR that would be required later in this century"  There are presently 1000+ (and growing) excess Gts of anthropogenic CO2 in the atmosphere right now. This legacy CO2 is the primary cause of the climate and ocean chemistry effects we are currently suffering under and due to its longevity this suffering will continue for many centuries to millenia (even if/when we get to zero emissions) unless anthro CDR is employed to hasten its removal. The goal of zero emissions only dictates the maximum CO2 and T that will be attained, it does nothing to more rapidly cool "the oven" once the oven is turned off. And in this case we don't have the option of taking the "goose" out of the oven to prevent overcooking. So, we have a 1000+ Gt CO2 problem right now. Why are we talking about the need for CDR as some later century requirement when it’s needed now to make sure our goose isn't ultimately cooked to a crisp?

 

2) Yes, there are physical, environmental, and social limitations to what CDR can do, but let's make sure those  limitations truly outweigh the benefits of helping save the planet from excess CO2. If we fail at effectively managing CO2, what will be the impacts be to non-indigenous, “Indigenous  and  traditional  communities’  land  tenure  and  rights, biosphere sustainability, biodiversity", food security, etc? There will be tradeoffs so let's make sure we are operating on facts and evidence, not myth and speculation in making decisions as to the costs, risks, and benefits of doing CDR. Those facts and evidence can only come from RDD&D done and evaluated under a system of merit, not politics, favoritism and who has the best lobbyists. (We can at least do better in the US than the 20 years of gov funded CDR R&D we've just experienced and now terminated.)

 

3) Why imply that "novel" CDR only requires geologic storage and that access to geologic storage limits novel CDR? There’s 40,0000+ Gt C (140,000+ Gt CO2 equivalent) already in other C reservoirs on Earth with lots of additional storage possible, esp in the ocean.

 

4) mCDR is apparently put in the "novel" category despite its already contributing half of the natural CDR that in total removes about 50% of our emissions annually. How “novel” and immature is mCDR considering it’s been around (been “in development”) for a few billion years longer than "conventional" trees and soils (and truly novel DAC and BECCS)?

 

5) And last but not least, that 'moral hazard' argument just won't die: "overreliance on CDR risks delaying the broader energy transition and decarbonization".  If framed properly there is no risk that CDR threatens emissions reduction because the former addressed legacy CO2 that emissions reduction doesn't touch. There are a thousand Gts up there right now that need removing, a quantity far larger and more impactful than the 42 Gt that will be emitted this year (and, yes, need to be reduced).  So, there is plenty of CO2 to go around, why are we pitting one method against another if both are needed?

 

Granted, this report's mission is to primarily address the emissions gap in achieving specific global T goals, but it is still disturbing to see CDR treated in such an offhand/dismissive way, apparently reflecting  high-level thinking within the IPCC/UNEP and other policy gatekeepers(?)

 

Regards,

Greg Rau

[Tom Goreau]

Thanks, Greg! What about SRM?

 

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[Benoit Lambert]

Dear CDRemovers, 

I have been following our Google CDR group for some time. I am always impressed by the scientific level. Yet I believe our brains do not serve us well when it comes to predictions. We seem to be wired to always anticipate the worst. It might have to do with dangers in nature, food shortages, « l’état de nature » as Thomas Hobbes referred to in The Leviathan, or, Machiavelli in The Prince. The summit of this legitimate fear has been reach with the entropy law, that applies to the fossil fuel era, but, not to the solar-wind-battery (SWB) Stellar new era, or the biogeotherapy times based on new science of soils. Let me try to explain what I mean. I’d love to receive reactions.  

When I was a student in Montreal University, a young teacher was receiving little considerations from his colleague, to the point it made me feel bad at times. Not a professor, he finally lost his position as a lecturer. The reason? He was in contact and researched a field nobody took seriously: futurology. He had all kinds of publicity on the topic on his office door. Futurology was dis-considered as « new-age », crazy stuff from California, with no solid scientific bases. Today Tony Seba, the chief futurologist, has proved a new law in human sciences, and, completely reversed the situation: technologies and innovations follow an S curve in their adoption. Their adoption is predictable. « As predictable as gravity » says Seba. Looking at 1500 innovations and adoptions, he shows they ALL follow the same adoption pattern: slow adoption at first, then super rapid adoption, followed by a ceiling. This mechanic is now (a little) more rapid than a century ago. The 900 000 prediction for sells of cell phones ended up being… 109 000 000, etc. Seba insist, « there is no exception ». It is just happening faster than before he says with his RethinkX team. Rather stunning, here is a non-academic proposing a social sciences law that works, all the time.  

Seba says we are in the middle of a clean energy revolution that will change everything, including for the climate crisis. The first major step will be the replacement of ALL current electricity within 5-7 years. Humanity went from 1 to 2 TW of solar power between 2022 and 2024. With wind and batteries, we double, largely, every 2 years: 4, 8, 16, 32 TW in 1932—the world’s electricity installed power is currently 30 TW. Then, replacing ALL energy will take another 10 years—indeed Seba predicts a sudden end for fossil fuels. This is an IT type revolution, exponential, turning logarithmic, Moore’s curve, etc. Just like with IT/iPhone/numeric photos, many will deny it is happening, especially current energy incumbents. Going solar-wind-batteries is not just a swap, SWB has an amazing number of consequences: developed countries get 10% richer, but, much more consequential, developing countries get 90% richer… Once installed, there is no coal, no petroleum, no gaz, no uranium needed, reducing polluting transports massively. The fact solar must aim at producing during the weeks with less sun, liberates free energy during the rest of the year, 11 or 11.5 months: Seba calls it « SWB superpower » and its main consequence, super-abundance. SWB is already the cheapest source of energy today. If you own a plant… the sole operating expenses are more pricy than switching to SWB… —and, as if this is not spectacular enough, SWB goes down 20% every two years. Current electricity plants have, in reality, no real value. Fossil fuels will disappear very fast, very suddenly. Again, this is not a swap of one energy for another, a commun mistake observers make. SWB implies all kinds of changes, self-driving cars using AI, transport on demand, transport as a service (TaaS) that will use much less space in urban environments, and, divide transportation cost by 10X. With time, batteries will improve, and, use 2-3 times less of their recycled minerals. Fossil fuels extraction and various mines will eventually close, especially considering technological innovations and substitutions, in particular sodium-ion batteries. Again, the co-benefits go in cascade—this is not simply the replacement of one product/commodity by another, all kinds of new possibilities appear.

Now regarding biogeotherapy I have developed with Thomas Goreau’s suggestions and support, the need for 1000 GtC02 captured and stored. It resembles our incapacity to anticipate SWB. A lot. Let me give you my personal experience. As a tree-planter, 20 four-months seasons, I have planted 3 000 000 trees. This is a conservative evaluation that might surprise some (80 days X 2 000 trees X 20 years = 3 200 000 trees, a conservative number). Crowther Lab in 2019 mentioned planting 1 000 000 000 000 trees would bring us back to 280 ppm. Divide a trillion by 3 M, you get 333 333, if you want to get this done in 5 years, not 20, you need 1.33 M tree planters, not considering new drone technics. We know lots of land is needed for that, the size of China, biodiversity of tree species, etc. Yet it is obviously not impossible at all. And, the (real) good news is that reforestation is far from being the only nature-based solution we have: no-till with cover crops, holistic grazing management promoted by Alan Savory (carbon ranching), biochar, mangroves, hemps, bamboo, seaweeds, rock weathering (remineralization), and, numerous other NbS I mention briefly in Biogeotherapy. A clarification: we have no choice. We must repair soils. Regenerative agriculture and carbon ranching are part of trophic chains, « the dynamic of grasses » as André Voisin wrote some 60 years ago. 

I am not saying here biogeotherapy is an easy task, just, easier than it appears at first sight. Just like the reduction of solar prices by more than a thousandX, CDRs can become win-win-win practices based on new knowledge about soils—on pedology the science of soils—with cascading co-benefits. SWB is a technology revolution, based on microchips that concentrate and move around protons. NbS is more a scientific revolution seeing soils holistically, with improved water and fertilizer holding capacities, healthy coucous-like loose soils. The result is a return to the holocene we shall have never left.  

Kind regards, 

Dr. Benoit Lambert

Cbiochar Inc., Sutton, Québec.
LinkedIn page: https://www.linkedin.com/in/benoit-lambert-ph-d-09b88510/
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[Dan Miller]

I like Tony Seba’s predictions and I believe he is correct that renewable energy (RE) will continue to grow rapidly and get cheaper, eventually replacing fossil fuels. However, CO2 lasts for 100s to 1000s of years in the atmosphere and it is already too high… the last time CO2 was today’s value of about 420 ppm, sea levels were 75 feet higher than today.  Plus making RE cheap means we will use much more: so far all RE (on net) has gone to new energy supply, not replacing fossil fuels (FF).

So, even if RE eventually replaces FF, we are still going over 2ºC which is catastrophic, and likely 3ºC. We will pass tipping points from which there is no recovery.  That is why SRM is needed in addition to CDR and emissions phase out.

As for “biogeotherapy,” as Kevin Anderson said: “Plant trees for good tree reasons, don’t plant them for carbon reasons.”  Also, Allan Savory work has not been shown to be valid scientifically, though he does have a devoted following.  I’m excited about nature based solutions such as biochar and rock weathering, but most biological approaches don’t pass the persistence threshold.

Regards,

Dan

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[Benoit Lambert]

Thank you Dan,
Here is a science compendium regarding holistic grazing management as a carbon net-negative practice.
https://soil4climate.org/science-compendium

[Greg Rau]

Thanks Dan and Benoit. I don't doubt that given enough (quality) time RE will replace FF, but as Dan says we are far from that happening, there are clearly forces afoot to prevent that from happening, and (quality= politically and environmentally stable) time here on Earth is being threatened. 

As for Crowther's trees, I seem to recall considerable  controversy about this as confirmed by a Google search and AI synthesis below*.  I'm sure that biology can participate to some degree in CDR, but as a reformed biologist myself and knowing the biogeochemical (and land use/political) complexities involved in maintaining living biomass or converting it to long term storage (biochar, BECCS, etc), I don't see how this can be the magic bullet.  Could genetic engineering be used to maximize bio CO2 capture/storage and qualify as "biotherapy"? There's socially-sanctioned gene therapy in human medicine, why not in environmental/planetary "therapy"? 🤔

Anyway, all of this is to say that The Gap Report and similar high level policy docs continue to emphasize emissions reduction and underplay CDR and esp SRM, all of which now need to be seriously considered given that emissions reduction cannot address the largest emerging threat  - long-lived, legacy CO2.  I'd say this situation is a consequence of thinking that zero emissions solves all problems rather than the real need to return to <=350 ppm CO2 (or pick a number) as rapidly as possible. This requires a major effort in CDR, or failing that, long term adaptation and/or SRM. (Y)Our choice? 

Regards,

Greg

ps Dan, I enjoy your "Climate Chat" on YouTube on Sundays https://www.youtube.com/channel/UC3BXcpYFCzTndJ9Fisi32qg

*AI Overview

Criticism of the Crowther 2019 "trillion trees" study includes the 

overestimation of suitable land for reforestation, underestimating negative impacts like local heating and impact on biodiversity, and the potential for planting trees to distract from necessary greenhouse gas emission cuts. Critics also pointed out that planting trees is not a silver bullet and that natural, diverse forests are more effective carbon sinks than plantations, an issue the study's author, Thomas Crowther, later acknowledged and corrected. 

Overestimated potential 

• Land availability: Critics argued the study overestimated the amount of land that could realistically and appropriately be forested, including areas like savannas and grasslands that are vital for biodiversity and carbon storage in their soils.
• Carbon sequestration: Some scientists questioned the study's estimates of how much carbon could be absorbed, citing that plantations often have lower carbon densities and release carbon when harvested.
• Ecological impacts: The study was criticized for ignoring potential negative local and regional effects, such as the warming effect of replacing light-colored surfaces like grasslands with dark-colored trees, and for suggesting planting in areas that are not suitable for forests. 

Oversimplification of the solution

• "Silver bullet" narrative: The study was interpreted by some as suggesting tree planting was a simple solution to climate change, which critics argue can lead to a false sense of security and distract from the urgent need to reduce greenhouse gas emissions.
• Focus on planting vs. conservation: Planting new trees does not have the same climate impact as protecting and restoring existing, mature forests, which are far more effective carbon sinks. 

Subsequent acknowledgments and corrections

• Study correction: Crowther's team later published corrections, admitting some headline claims were "incorrect" and that data contained "errors".
• Nuanced perspective: Crowther has since emphasized that conservation and restoration of existing forests are more important than planting new trees and has cautioned against using tree planting as an excuse to ignore emissions cuts.
• Advocacy for responsible practices: Crowther has been vocal about the need for socially and ecologically responsible restoration, including working with local communities and Indigenous populations, rather than mass plantations that can harm biodiversity and local economies. 

To view this discussion visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/635CFB8B-6B54-47DE-8287-D3CEFEA4F8C6%40rodagroup.com.

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Greg H. Rau, Ph.D.

Senior Research Scientist
Institute of Marine Sciences
Univer. California, Santa Cruz
https://www.researchgate.net/profile/Greg_Rau
Co-founder and manager, the Carbon Dioxide Removal Google group
Co-founder and Senior Scientist, Planetary Technologies, Inc.
510 582 5578

510 363 1519 c

[Benoit Lambert]

I am afraid you are right Greg, putting GHG in the atmosphere is not the only problem we have... 

The sub-title of Biogeotherapy is « life as a geological healing force »… yes we can… use life and associated carbon to fix things. One of the great books I read on this topic are from David Montgomery Dirt—The erosion of civilisations, and, Growing a revolution—Bringing our soil back to like. The degree of misunderstanding about soils is staggering… In a passage of Biogeotherapy I write: 

"Soils are fragile. Some more than others. But their oxidation by

farmers shares a pattern; a pattern we now know how to avoid.
Better yet we know how to reverse soil degradation, how to build
new soils, and how to “grow fertility.” We need to reverse what
Edward H. Faulkner called Plowman’s Folly, the title of his book.
Published in 1943, it contains this amazing declaration before
Permaculture: “The truth is that no one has ever advanced a
scientific reason for plowing.” Today, regenerative revolution
introduces science in agriculture. Not by plant selection as our
ancestors did, or by breeding the stronger animals, but by
recognizing carbon is at the heart of living soils, sustainability, and
profits for farmers."

[Bruce Melton -- Austin, Texas]

Thanks Greg. I agree with most of what you say, but with different words, except for a few things... 

1) The nonlinear rate of change... Our climate culture is based on change that is tethered to the rate of emissions, where feedbacks are still poorly understood and where positive feedbacks with warming are generally much more meaningful than negative feedbacks.

2) The tipping enigma... Climate pollution mitigation targets are wrongly tied to the point of no return in most systems. "Tipping" and earth systems (ecological systems) degradation and ensuing collapse all identify the same thing - the tipping response, with two phases: activation and the point of no return. Tipping activation in most systems is related to the onset of degradation, when a system's evolutionary boundary conditions are exceeded. As degradation proceeds, the system rapidly loses its ability to sequester carbon and flips to emissions. Degradation usually proceeds with its own positive feedbacks, increasing degradation response nonlinearly with little change unless the warming effects that started the degradation are removed. Also, once degradation begins, systems begin to cascade from interconnected responses, cascades do not wait for the point of no return. Once degradation exceeds a certain amount, most systems will fail to self-restore even if the degradation forcing is removed. This is the second phase of tipping - the point of no return. This is the conundrum with our climate culture: it does not meaningfully consider that once tipping is activated (degradation begins) most systems collapse and the point of no return is forgone without removing the forcing that activated the tipping response. Our climate culture then is operating in a two-variate reality with only one variate represented in future pathways.

3) Our climate culture is over-reliant on natural systems because of activated tipping (degradation)... Because most systems are now degrading, most systems' ability to sequester carbon is compromised or reversed like in the Amazon and likely all tropical forests, because the evolutionary boundaries of these systems have been exceeded.

4) The consensus combines CDR strategies, biasing the efficacy of sub-sectors... Few analyses of CDR break this sector into sub-sectors, but rely on our climate culture's predominance of enhancing natural systems sequestration. Some sub-sectors of CDR have much greater capacity, easier scalability, and fewer side effects. This "feature" of our climate culture then biases some strategies by including them with the less efficient more difficult strategies. "Novel" strategies are a big issue. There are three DAC strategies that have been a staple of industry with even more widespread use of their components -- for a hundred years or more. This is one of my favorite discussions, where the processes associated with beer in Bavaria in the 19th century, illustrate that there are industrial CDR processes that are nowhere near novel. See, The History of Carbon Dioxide Removal.

5) The overshoot bias... Implementing CDR faster, to address the point of no return that is not considered in our climate culture, cannot be achieved with delaying CDR implementation to address net zero's hard to decarbonize sectors and the consensus modeling need to pull back overshoot therefor, the characteristics of using CDR to address the point of no return are absent in our future consensus pathways.

6) Risk-Risk analysis... Likewise, because the point of no return is not considered in our consensus pathways, risks of exceeding the point of no return are not considered.

7) Required removals for restoration... There is an assumption in restorationland, that we have to remove all the excess human-emitted carbon to avoid the point of no return. The target to stabilize activated tipping elements; to stabilize ongoing degradation, is the natural variation of our old climate, or the boundaries of the evolution of our Earth's system. Generally, the lit describes natural variation maximum as 350 ppm CO2 (about 1 C), not pre-industrial CO2 at 280 ppm. This means we do not have to remove all the excess CO2, only half(ish), to lower CO2 back to within natural variation.

8) Last: The Moral Hazard and 11 understating biases of our climate culture... Our climate culture has a one-track mission with huge momentum and very meaningful psychological constraints. Instead of addressing the climate pollution problem like we address almost all other pollution problems; by creating the things we need and treating the pollution generated so we can be safe, our culture has decided, with much input from the 11 understating biases, that elimination is the answer. The moral hazard then is a complex behavior that is driven by the understating biases with a psychological feedback that comes from 30 years of the smartest people in the world telling us eliminating climate pollution emissions is the answer. This creates momentum that feeds back into the continuation of moral hazard behaviors. I have collected scores of references for these biases and present them in An Introduction to Advanced Climate Change on slides 28-34.

MeltOn

https://climatediscovery.org/History_of_Carbon_Dioxide_Removal_Draft.docx

Bruce Melton PE
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
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