Question re: re-equilibration of carbon stored in the ocean

[briancar...@gmail.com]

To the CDR group,

I'm starting Paul Hawken's new book, "Regeneration" and it raises a question about something I had thought was settled science. In the introduction he says that scientists have long believed that if and when atmospheric levels of CO2 are substantially reduced, there will be a long period of re-equilibration with carbon being gradually released from oceans, so that a return to pre-industrial levels would take many decades to accomplish. But, according to Hawken, this assumption has more recently been challenged and if CO2 levels were brought down successfully there would be reduction in atmospheric levels within about 10 years. 

I'm not asking about additional complicating factors such as methane release etc, but only whether there have been new results showing that the speed of ocean release is not a limiting factor for reducing atmospheric CO2.

Thanks,

Brian Cartwright

[Mike Robinson]

The same question applies in reverse. Many projects are planning to pull CO2 out of ocean water with the assumption that the ocean will then pull more CO2 from the atmosphere. I too thought it was settled science that the ocean and atmosphere will always remain in balance in terms of CO2 partial pressure. Is that not settled?

Speaking of settled science - is there a firm scientific basis for the assumption that large quantities of organic matter stored below 1Km deep in the ocean will be sequestered for centuries? I have seen this idea asserted repeatedly, and I understand the premise that "there's almost nothing going on down there", but do we really know that? If we use something like artificial upwelling or OIF to purposely stuff many Gt's of organic carbon material deep in the ocean over a short time frame (decades), how sure can we be that there will be no unintended consequences? Just looking for input from folks who know a lot more about this. Thanks!

[Ken Caldeira]

To a first approximation, a CO2 removal is equal and opposite to a CO2 emission.

You can see this is true because if we are at a time of net emissions, there is effectively no difference between having the same emissions plus one ton of CDR or just having one ton less emissions. 

So, despite fanciful cases of high negative emissions taking advantage of some non-linearities, to a first approximation, just think of a CO2 removal as being a negative emission.

The temperature change from a CO2 removal would be felt within a decade, but the CO2 implications will take a long time to unfold.

https://www.kiel-earth-institute.de/CDR_Model_Intercomparison_Project.html

https://www.nature.com/articles/nclimate2729

--
You received this message because you are subscribed to the Google Groups "Carbon Dioxide Removal" group.
To unsubscribe from this group and stop receiving emails from it, send an email to CarbonDioxideRem...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/84855ab3-fc15-47a6-b064-d8da48da6dc4n%40googlegroups.com.

[briancar...@gmail.com]

Thanks Mike and Ken for your responses. I would have expected the complicating factor of deep ocean carbon taking longer to be equilibrated. Otherwise I'm still looking for an answer about how long overall re-equilibration would take.

For several years I've been telling people that, hypothetically of course, even if emissions went to zero today and we started sequestering substantial amounts of atmospheric CO2, that there would be a period of some decades during which the much larger store of carbon in oceans would be released, so that getting down to pre-industrial levels or even, say 350 ppm of CO2, would not be seen in the short term. Hawken is suggesting that new results contradict this; does anyone know of such research?

I think this is a crucial question for climate science and activism. If it is the case that lowering atmospheric carbon is not feasible in our lifetimes even with the best case efforts of emission reduction, then we also need to pursue other methods of global cooling not focused on carbon. Not being a fan of SRM, I am most interested in the large number of landscape and ecosystem restoration methods which promise to enhance hydrological cooling through increased vegetation and hydration of degraded landscapes: deforested, desertified and urban areas.

Brian Cartwright

[Tom Goreau]

The ocean turnover time is 1500 years, as determined from radiocarbon measurements.

 

This applies to heat uptake as well as CO2.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

http://www.crcpress.com/product/isbn/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

http://www.crcpress.com/product/isbn/9781466557734

 

No one can change the past, everybody can change the future

 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/047cee68-f582-4415-b8e8-8438327b6f75n%40googlegroups.com.

[H simmens]

Brian,

This is the most comprehensive and accessible article I have found that addresses your question though it focuses on temperature rather than CO2 concentrations. 

Here’s what I take away as the money quote. 

“ Combining all of these uncertainties suggests that the best estimate of the effects of zero CO2 is around 0C +/- 0.3C for the century after emissions go to zero, while the effects of zero GHGs and aerosols would be around -0.2C +/- 0.5C.”

https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached

Herb

Herb Simmens

Author A Climate Vocabulary of the Future

@herbsimmens

On Sep 24, 2021, at 9:42 AM, briancar...@gmail.com <briancar...@gmail.com> wrote:

Thanks Mike and Ken for your responses. I would have expected the complicating factor of deep ocean carbon taking longer to be equilibrated. Otherwise I'm still looking for an answer about how long overall re-equilibration would take.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/047cee68-f582-4415-b8e8-8438327b6f75n%40googlegroups.com.

[Bruce Melton -- Austin, Texas]

I want to point out the scenario bias with what we see in the literature and the big picture of future climate pathways.

There are no scenarios in the consensus world that go lower than net zero or 1.5 C. The vast body of literature does not consider quantities of atmospheric removal of CO2 (or other GHGs) needed for restoration scenarios, where climate restoration is defined as returning our climate to within the evolutionary boundaries of stable Earth systems. So when understanding the big picture with findings on the trajectory of our future climate and the associated behavior of Earth systems, it must be understood that Earth systems will further deteriorate with further warming with all consensus scenarios. Further warming increases temperature and other feedback processes, that include atmospheric/biosphere gas equilibrium processes, as our current climate moves farther away from the evolutionary boundaries of our former climate.

Hansen's "Young People's Burden..." suggests the upper limits of the evolutionary boundary conditions of our old climate, that represent the evolution of Earth systems, is centered around 350 ppm CO2 ("Holocene maximum" below). Our Earth systems will not instantly reevolve to new boundary conditions when boundary conditions change beyond systems' evolution. If we can turn the temperature around fast enough and cool Earth back to withing its systems' evolutionary boundaries before these systems complete their collapses that have already begun (Lenton 2019), Earth systems' evolutionary equilibrium will be maintained and outgassing begins.

If we continue to warm to 1.5 C as all the consensus scenarios suggest, we move farther away from Earth systems' equilibrium and sequestration increases. In other words, increased atmospheric CO2 with 1.5 C and net zero targets increases partial pressures of atmospheric gases further from today, causing greater biosphere absorption --if-- Earth systems remain healthy. Only through restoration scenarios where we lower atmospheric CO2 below Earth systems' equilibrium evolution will outgassing of sinks occur, with the exception of collapsing Earth systems where sequestration is degraded, eliminated or reversed.

Because there are no restoration scenarios accepted by consensus reporting, what is described above is not included in the vast majority of science on pathways our future climate will take, especially consensus pathways. When we view findings or popular press reporting of findings, it is vitally important to understand the basis for findings. If we incur further warming, of course climate processes are irreversible from where we are today, in time frames that matter.  If restoration scenarios are not included in our vision of our future climate, there is literally an existential bias in what findings reveal.

Caveat: The above concepts are generalizations. Some (all) systems behave differently and their behavior varies from the generalities described above. But in general, future climate pathway findings exhibit a bias because they only consider scenarios with further warming.

Bruce

Bruce Melton PE
Director, Climate Change Now Initiative, 501c3
President, Melton Engineering Services Austin
8103 Kirkham Drive
Austin, Texas 78736
(512)799-7998
ClimateDiscovery.org
MeltonEngineering.com
Face...@Bruce.Melton.395
Inst...@Bruce.C.Melton
The Band Climate Change
Twitter - BruceCMelton1

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/436F1CA5-6D37-4713-B0E7-749BC8248E32%40gmail.com.

[Tom Goreau]

A pre-industrial GHG goal is needed to avoid serious disruption, which a 1.5 warming goal minimizes only with regard to worse: 2 or 5 degrees warming.

 

We need to start Geotherapy by planting trees and putting biochar into soil and regenerating blue carbon RIGHT NOW just as fast as we can, just in case a high technology fix can be developed in time to help later.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

http://www.crcpress.com/product/isbn/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

http://www.crcpress.com/product/isbn/9781466557734

 

No one can change the past, everybody can change the future

 

 

 

From: <carbondiox...@googlegroups.com> on behalf of "Bruce Melton -- Austin, Texas" <bme...@earthlink.net>
Date: Friday, September 24, 2021 at 11:50 AM
To: "carbondiox...@googlegroups.com" <carbondiox...@googlegroups.com>
Subject: Re: [CDR] Re: Question re: re-equilibration of carbon stored in the ocean

 

I want to point out the scenario bias with what we see in the literature and the big picture of future climate pathways.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/f6048477-f5f7-8486-ec6b-91175362c9d0%40earthlink.net.

[Adam Sacks]

The recent IPCC report, Summary for Policymakers, says:

B.1 Global surface temperature will continue to increase until at least the mid-century
under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be
exceeded during the 21st century unless deep reductions in CO2 and other greenhouse
gas emissions occur in the coming decades.  (SPM p. 16)

IOW, there's a 30-year time lag (which has long been known) between what happens in the atmosphere and what happens on the ground.

Not exactly your question, Brian, but a related opinion . . . 

Adam

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/436F1CA5-6D37-4713-B0E7-749BC8248E32%40gmail.com.

[Greg Rau]

This modeling paper speaks to asymetries in emissions reduction vs CDR:

https://www.nature.com/articles/s41558-021-01061-2

Negative CO2 emissions are a key mitigation measure in emission scenarios consistent with temperature limits adopted by the Paris Agreement. It is commonly assumed that the climate–carbon cycle response to a negative CO2emission is equal in magnitude and opposite in sign to the response to an equivalent positive CO2 emission. Here we test the hypothesis that this response is symmetric by forcing an Earth system model with positive and negative CO2emission pulses of varying magnitude and applied from different climate states. Results indicate that a CO2 emission into the atmosphere is more effective at raising atmospheric CO2 than an equivalent CO2 removal is at lowering it, with the asymmetry increasing with the magnitude of the emission/removal. The findings of this study imply that offsetting positive CO2 emissions with negative emissions of the same magnitude could result in a different climate outcome than avoiding the CO2 emissions.

See also attached.

What exactly does Hawken say about the amount of CDR required to "regnererate" the world?

Greg

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAA2mHQnKSaXyzo8N9m3jBEEDfKPz0oW-it0QLgDcMSC4f39L9w%40mail.gmail.com.

[briancar...@gmail.com]

To Greg and group,

I've transcribed here the relevant quote from Hawken's first chapter, also titled "Regeneration":

" In December 2020 Dr Joeri Rogelj  of the Grantham Institute of London and a lead author of the 6th assessment of the IPCC, made a remarkable statement:   "It is our best understanding that if we bring carbon dioxide emissions down to net zero, the warming will level off. The climate will stabilize within a decade or two. There will be very little to no additional warming. Our best estimate is zero". This was a remarkable change in scientific consensus. For decades, it was assumed that if we were able to stop our carbon emissions the momentum of warming would continue for centuries. That was mistaken. Climate science now indicates that global warming would begin to recede after we achieve zero carbon emissions. "

(My original post above also referred to the legacy carbon stored in the ocean, which I've always been told is a crucial factor.)

Brian

[briancar...@gmail.com]

Also to Greg and group:

Let me reiterate that my question is whether there are some new results in research that contradict previous assumptions about re-equilibration of CO2 levels in the event of negative emissions. In posing my question based on the Rogelj information in the Hawken book, I made somewhat of a leap since Rogelj only says warming would come down within a decade or two, not that CO2 would level off or go down. I can think of many factors (eg aerosol masking) that would complicate the temperature forecasting, but I was assuming that if oceans continued to outgas carbon after negative emissions, there would continue to be a forcing that raises temperatures. Is there some reason to question that assumption?

Brian

[Robert Tulip]

Brian, thanks for this discussion.  I find it hard to understand how net zero could stabilise the climate with liveable conditions, and without massive risk. 

 

Net zero by 2050 would result in a trillion tonnes of anthropogenic carbon in the air that would then stay there for a long time unless there are large technological removals. 

 

The last time GHGs were that high was millions of years ago, when temperatures and sea level were much higher than today.

 

Simple earth system equilibrium calculations suggest that without removing that extra carbon, higher temperature and sea level are eventually inevitable. And destabilising risks to forests, currents, ice, etc are severe.

 

Net zero looks to be a very complacent goal, in terms of human security and biodiversity conservation.

 

What am I missing?

 

Regards, Robert

 

From: carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> On Behalf Of briancar...@gmail.com
Sent: Monday, 27 September 2021 2:22 AM
To: Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>
Subject: Re: [CDR] Re: Question re: re-equilibration of carbon stored in the ocean

 

To Greg and group,

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/9cb7728e-2260-4c4d-bdc8-4992ae4226adn%40googlegroups.com.

[briancar...@gmail.com]

Robert, I agree that 2050 net zero is as you say, a complacent goal. Also a convenient way for policymakers to kick the can down the road much too far.

I could have been much clearer in posing the question at the top of this post. The IPCC scientist Joeri Rogelj quoted in Hawken's book asserts that if we reach net zero emissions, "warming will level off" in ~1-2 decades. How is this assertion justified? If atmospheric carbon is substantially lower, how quickly is carbon in the oceans released to create equilibrium? Since the quantity of carbon held in the ocean is so much greater than in the atmosphere, this rate of release should be one of the most important variables. Is there consensus on what that rate is? In this thread Herb Simmens links to a Carbon Brief article that cites a NASA FAQ from 2007 that says, 

 "even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades, if not centuries." 

If that projection is correct, to what extent does it result from the turnover of ocean carbon? Is there consensus on the rate of that turnover? When Tom Goreau tells us (above in thread) that ocean turnover time is 1500 years, what would that look like if we achieve net zero by 2030? Would the carbon content in the ocean be graduated by layers? 

Again, I'm not looking for comprehensive analysis or temperature forecast, only this factor of carbon re-equilbration between ocean and atmosphere. 

Brian

[Adam Sacks]

GHG's trap heat, they don't generate it.  If we turn down the thermostat, we'll cool off.  The primary mechanism for this is restoring photosynthesis on roughly 5 billion desertified acres.  Latent heat that is used in photosynthesis doesn't raise temperature, it evaporates water which cools the biosphere and can generate high-albedo clouds (depending on condensation nuclei) which block sunlight.  When this process is well established, ocean interactions with the atmosphere will be of far less consequence.

But of course if we insist on pumping heat-trapping gases into the skies, eventually we may completely overwhelm the Earth's cooling systems.  But why would we want to do that?

Adam

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/1a4b5ca8-b1f7-4b2e-add3-11d048f4a20an%40googlegroups.com.

[Dan Miller]

The basics are as follows:

*IF* we bring emissions to zero:

1. Warming from the Energy Imbalance (warming in the pipeline) is offset by continue CO2 uptake by the oceans (at the current rate since the amount of ocean CO2 uptake is determined by the total CO2 in the atmosphere, not yearly emissions).

2. Warming due to the loss of aerosols (e.g., coal smoke) is offset by the disappearance of short-term GHGs (e.g., methane) over the next couple of decades.

Of course, Earth system feedbacks such as permafrost and shallow Arctic clathrate melting are not accounted for and could throw the whole thing off.

Dan

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/cfb0e6ca-892a-4954-88ed-52c1ab633e2dn%40googlegroups.com.

[briancar...@gmail.com]

I will stop nagging but only ask if anyone has an answer for my specific question stated now several times.

Brian

[Albert Bates]

Brian,

I was hoping to hear a better answer than my own, but like you, still waiting. My understanding relies upon the ocean CO2 feedback mechanism described in AR5  [IPCC Fifth Assessment Report: Climate Change. 2013. Working Group I: The Physical Science Basis. 6.5 Potential Effects of Carbon Dioxide Removal Methods and Solar Radiation Management on the Carbon Cycle. 546-548.] As CO2 is reduced in the atmosphere, CO2 dissolved in the ocean begins to outgas until a new kinetic balance with the atmosphere is restored. Because of this effect, the amount of atmospheric CO2 removed must be roughly twice as much as might otherwise be expected, IPCC said. It is not as simple as that because of ocean mixing effects and how much dissolved carbon is close to the surface (which is where Tom's number of 1500 years comes into play) and other variables like ocean temperature, plankton, and wave action.

I believe re-equilibration will take longer than a few decades to return to pre-industrial atmospheric concentrations but feedbacks to drawdown are large unknowns. I am just starting to take Hawken's new course on the Commune platform and read his book. I might also note that Joeri Rogelj published a paper in 2019 discounting the likelihood of a significant warming surge from removing the aerosol masking effect. Lately Jim Hansen has been looking more carefully at that and urging caution.

Albert

[Ken Caldeira]

Brian, 

I am not sure about your point 2. Maybe correct but I have not investigated.

I think you have point 1 correct.

Best,

Ken

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/e91f2b03-1cac-4c49-9092-bc4d0161cce9n%40googlegroups.com.

[Andrew Lockley]

At CEC 15 there was a presentation (Ken's?) showing the persistent effects on ocean water. Once water has downwelled, it's no longer in contact with the atmosphere. It cannot then exchange heat (or CO2) with the atmosphere, and exchange with adjacent water masses is limited (presumably more so in laminar flow).

Until water is down welled, it's much like soft drinks. Opening the can causes the dissolved CO2 to degas. This happens from absolute not partial pressure change in this example, but the effect is equivalent. 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAKNUXC0kA3%3DxzWoVwvpmk1JFvTd%2BVYe0dMHFVJbJ00XLHE2znw%40mail.gmail.com.

[Tom Goreau]

It’s not quite right to imply that the temperature is “frozen in” once water leaves the surface.

 

The downwelled water is constantly exchanging heat with other water masses in the ocean through convection and eddy diffusion along pycnocline density surfaces (NOT laminar flow or diffusiion, which is far slower), and when it returns to the surface, around 1500 years later on the average, it will then re-equilibrate temperature with the atmosphere boundary layer.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

http://www.crcpress.com/product/isbn/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

http://www.crcpress.com/product/isbn/9781466557734

 

No one can change the past, everybody can change the future

 

Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away

 

Geotherapy: Regenerating ecosystem services to reverse climate change

 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-042rrMdC0BcNAXhA06WtzWr56%2Bs17doctCVS%2Bigm7wM-A%40mail.gmail.com.

[Chris Vivian]

Andrew,

 

You said:

 

“Until water is down welled, it's much like soft drinks. Opening the can causes the dissolved CO2 to degas. This happens from absolute not partial pressure change in this example, but the effect is equivalent.”.

 

However, this is not the case as CO2 in soft drinks behaves differently from CO2 in sea water. In soft drinks CO2 is in the form of dissolved gas whereas in sea water very little CO2 is in the form of dissolved gas with most as bicarbonate and some as carbonate. The proportions will vary with pH – see the Bjerrum diagram showing the relative concentrations of the carbon species in seawater according to pH:

 

 

As you can see, the CO2 (aq) concentration at seawater pH of around 8 is a tiny fraction of the bicarbonate and carbonate concentrations – note the logarithmic scale.

 

Best wishes

 

Chris.

 

From: carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> On Behalf Of Andrew Lockley
Sent: 29 November 2021 22:02
Cc: Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>
Subject: Re: [CDR] Question re: re-equilibration of carbon stored in the ocean

 

At CEC 15 there was a presentation (Ken's?) showing the persistent effects on ocean water. Once water has downwelled, it's no longer in contact with the atmosphere. It cannot then exchange heat (or CO2) with the atmosphere, and exchange with adjacent water masses is limited (presumably more so in laminar flow).

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-042rrMdC0BcNAXhA06WtzWr56%2Bs17doctCVS%2Bigm7wM-A%40mail.gmail.com.

[Andrew Lockley]

It's a simplification. The degas process still occurs as partial pressure is reduced. 

In response to Tom's point, clearly there is mixing between adjacent water masses, but I simply pointed out that the temp/CO2 differences are persistent.

As a general point, it can be intimidating for posters, if their general point is overlooked and minor details are challenged. Forgive me if I don't respond further. 

Andrew 

[Chris Vivian]

Andrew,

 

Your post may be a simplification but your comparison between the release of CO2 from soft drinks and getting to equilibrium between CO2 in the atmosphere and CO2 in sea water after removal of CO2 from sea water is not a valid one as I said previously.

 

Also, the equilibration of the ocean with the atmosphere is not instantaneous but can take from days to weeks or longer. See the paper by Bach et al. (2021) – https://www.nature.com/articles/s41467-021-22837-2 who say:

 

“Atmospheric CO2 influx into the surface seawater, after CO2-fixation by Sargassum, takes 2.5–18 times longer than the CO2-deficient seawater remains in contact with the atmosphere, potentially hindering CDR verification.”

 

Also, note that Planetary Hydrogen (https://www.planetaryhydrogen.com/) in their presentations have assumed a period of weeks to months for equilibration of CO2 after ocean alkalinity enhancement.

 

Also, some parts of the ocean appear not to be in equilibrium with the atmosphere  e.g. Karl and Letelier (2008) - https://www.int-res.com/abstracts/meps/v364/p257-268/ - say this about the Pacific Ocean at Station ALOHA, so it would appear that equilibrium cannot be assumed to be inevitable.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-078xkzT7QBnkP_pUAYiPt-Tg1KavBRnHxcOjaWKenG_kQ%40mail.gmail.com.

[Tom Goreau]

Sorry to pile on, Andrew! As Chris points out, ocean CO2 is much more complicated than a soda bottle, a misleading analogy worth correcting.

 

Measurements of CO2 in surface water and air have been done worldwide for decades and are rarely in equilibrium. So that is rarely the starting point for deep water.

 

In general tropical waters are supersaturated and polar waters undersaturated compared to the atmosphere, as expected from solubility coefficients, so there are strong regional and seasonal fluxes in both directions vertically and horizontally.

 

Dissolved CO2 is almost never limiting for marine phytoplankton, except that it can be locally depleted inside dense green “pea soup” blooms where CO2 uptake exceeds the rate at which bicarbonate can resupply it.

 

Part of that disequilibrium is because hydration of CO2 is the kinetically slow, rate-limiting step, and so is largely mediated enzymatically by carbonic anhydrase, and affected by surface microfilms.

 

Andrew’s point though was purely about subsurface transport and equilibration, but there are significant CO2 sources and sinks WITHIN the ocean, and very rapid horizontal mixing of both heat and CO2 by eddies along density surfaces, but much less vertical mixing, thus keeping the lid on acid high CO2 bottom waters fed by decomposition of all that organic matter falling to the bottom.

 

Small changes in ocean circulation can greatly change the rate and location at which that CO2 comes back to the surface, as it must eventually.

 

Dumping algae on the deep ocean bottom gives you around 1500 years CO2 delay on the average, but much less in the Atlantic.

 

Bicarbonate alkalinization gives around 100,000 years of  carbon storage.

Limestone and black carbon (high grade biochar) a few 100,000,000 years.

 

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance

Chief Scientist, Blue Regeneration SL
President, Biorock Technology Inc.

Technical Advisor, Blue Guardians Programme, SIDS DOCK

37 Pleasant Street, Cambridge, MA 02139

gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226 (leave message)

 

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase

http://www.crcpress.com/product/isbn/9781466595392

 

Innovative Methods of Marine Ecosystem Restoration

http://www.crcpress.com/product/isbn/9781466557734

 

No one can change the past, everybody can change the future

 

Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away

 

Geotherapy: Regenerating ecosystem services to reverse climate change

 

 

 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/0c2901d7e6ab%24eed87c00%24cc897400%24%40btinternet.com.

[Peter Flynn]

Two comments.

 

The comment that sea water takes time to reach equilibrium with atmospheric CO2 is correct; transfer of CO2 to water is the rate limiting step for surface grown biomass. It also helps explain why one gets ocean spring “blooms” rather than persistent growth of biomass. But regardless: water in the North Atlantic, despite replenishment by the Gulf Stream, is essentially saturated in CO2 prior to downwelling: dats is in p 206 in

 

Zhou, S., Flynn, P.C. Geoengineering Downwelling Ocean Currents: A Cost Assessment. Climatic Change 71, 203–220 (2005). https://doi.org/10.1007/s10584-005-5933-0

 

Peter

 

Peter Flynn, P. Eng., Ph. D.

Emeritus Professor and Poole Chair in Management for Engineers

Department of Mechanical Engineering

University of Alberta

Edmonton, Alberta, Canada

1 928 451 4455

peter...@ualberta.ca

 

 

 

From: 'Chris Vivian' via Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>
Sent: Wednesday, December 1, 2021 5:07 AM
To: 'Andrew Lockley' <andrew....@gmail.com>

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/0c2901d7e6ab%24eed87c00%24cc897400%24%40btinternet.com.

[briancar...@gmail.com]

This New York Times intreractive article brings up (about 2/3 into the text) that researchers are finding legacy CO2 in upwellings in Antarctic currents. Thanks to posters who are showing the complexity of this topic.

The Antarctic Is Signaling Big Climate Trouble. - The New York Times (nytimes.com)

Brian Cartwright

[Peter Flynn]

I have been slightly puzzled by comments of late that Antarctic waters are undersaturated in CO2.

 

Some years back, Songjian Zhou and I looked at ways to get more CO2 into the deep ocean, and we speculated that North Atlantic water would be undersaturated in CO2, since it had a component of the warm Gulf Stream flowing north. The thought was that CO2 uptake took time, so the cold water in the North Atlantic would not have equilibrated. We found data that suggested that this is simply wrong: numerous samples indicated near saturation in CO2. We abandoned the thought of exploring ways to enhance CO2 concentration in the North Atlantic Deep Water, the downwelling current that is the offset of the Gulf Stream. Data on saturation in the North Atlantic is in the attached paper.

 

So the thought that this is not the case in the Antarctic is interesting. Perhaps even moreso because of the report of upwelling deep water in the Antarctic degassing; I cannot imagine that this component would degas past saturation.

 

Peter Flynn

 

Peter Flynn, P. Eng., Ph. D.

Emeritus Professor and Poole Chair in Management for Engineers

Department of Mechanical Engineering

University of Alberta

Edmonton, Alberta, Canada

1 928 451 4455

peter...@ualberta.ca

 

 

 

As you can see, the CO2 (aq) concentration at seawater pH of around 8 is a tiny fraction of the bicarbonate and carbonate concentrations – note the logarithmic scale.

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/8ad7e120-f703-4ef3-9adf-c5a362207a0en%40googlegroups.com.

[Tom Goreau]

The atmospheric data in Long et al (cited below) show clear strong Antarctic Circumpolar Current uptake of CO2 from the atmosphere in the Southern Hemisphere Summer (just starting):

The Antarctic Circumpolar Current ACC is the largest cold water current, highly unsaturated in CO2, and has the strongest ocean waves to mix water with air, making it the most crucial zone controlling global CO2 uptake from atmosphere to the ocean. New papers of measurements on very different time scales show these fluxes can change dramatically, with major carbon dioxide removal implications.

Long et al, 2021, Strong Southern Ocean carbon uptake evident in airborne observations, Science, 374:1275-1280, presents aircraft measurements in 2016 that show rapid seasonal changes in CO2 atmosphere ocean fluxes, with the largest atmosphere drawdown during the southern summer, confirmed by surface measurements from 1999-2019. They discuss the need for more air-borne measurements to quantify changing fluxes and do not seem to discuss long-term trends.

Wu, S., Lembke-Jene, L., Lamy, F. et al. Orbital- and millennial-scale Antarctic Circumpolar Current variability in Drake Passage over the past 140,000 years. Nat Commun 12, 3948 (2021). https://doi.org/10.1038/s41467-021-24264-9 discuss changes in the ACC over an entire glacial/interglacial cycle. Sediments at the bottom of the Drake Passage, the critical choke point of the ACC, show strong variations in grain size related to current velocity, with highest speeds in warm periods and least during glaciations. The last Interglacial around 130,000 years ago was 1-2 C warmer than today, and the ACC velocity even higher than present. Increasing velocities expected with global warming should cause more release of CO2 from ocean to atmosphere, potentially turning a sink into a source.

It should be noted that the 2021 Antarctic winter had an extremely strong cold anomaly and Polar High Pressure Zone, surrounded by very low pressure zone over the ACC. The high pressure gradient drove very strong, cold, outward katabatic winds from the Ice Cap over the ACC, and strong winds caused very high waves and atmosphere-ocean fluxes. When the 2021 Southern Summer began, the Polar High Pressure Zone disappeared, strongly weakening wind and wave induced atmosphere-ocean CO2 transport. Dramatic weather changes like this should be reflected in rapidly changing CO2 sources and sinks.

Similar airborne sensing is needed over the world’s strongest, and hottest ocean currents, the Equatorial Currents, the major source of CO2 from ocean to atmosphere. These are subject to strong changes on ENSO, Madden-Julian, and other cycles, and after a very prolonged La Niña, the next El Niño, which appears to be starting, could cause large variations in the major ocean-atmosphere CO2 sources. 

Small fluctuations in either current could dramatically change atmosphere CO2 trends. As Wally Broecker used to point out: you should expect surprises when you mess with climate! 

To view this discussion on the web visit https://groups.google.com/d/msgid/CarbonDioxideRemoval/09ae519b8ecb2ea87d26e3f59393ce19%40mail.gmail.com.