Pinatubo and CO2 sinks

[Tom Goreau]

Some proponents of ocean fertilization claim that the Mount Pinatubo eruption somehow sucked large amounts of CO2 out of the atmosphere into the ocean, and that they can replicate these effects cheaply.

 

Such large carbon sinks in 1991 do not appear in global land or ocean CO2 budgets (below, from Friedlingstein et al., 2025), and the slowdown in CO2 increase that year may be as ephemeral or imaginary as the so-called “global warming hiatus”.

 

 

 

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

Chief Scientist, Biorock Technology Inc., Blue Regeneration SL

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

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Innovative Methods of Marine Ecosystem Restoration

https://www.taylorfrancis.com/books/oa-edit/10.1201/b14314/innovative-methods-marine-ecosystem-restoration-robert-kent-trench-thomas-goreau

 

On the Nature of Things: The Scientific Photography of Fritz Goro

 

Geotherapy: Regenerating ecosystem services to reverse climate change

 

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[pfieko]

Tom- Thank you for pointing out the gap between the current literature and the Keeling curve. I believe I'm the leading proponent of Pinatubo CDR.

Here's the data, from our The Pinatubo CO2 pause suggests a rapidly testable path to multi-Gt mCDR (preprint): 

This Mauna Loa data directly from NOAA is explicitly clear about the removal of 2.25 ppm which showed no sign of coming back 14 years later (or 32 years later).

You might ask, "Why don't the budgets (models) fit the Mauna Loa data?" 

Probably because they never tried--I've not seen any that compared their model to the historical data as we do. Peer reviewed science is about getting the data to fit existing theory. If the data doesn't fit the theory, it's not science and doesn't get published. That's the given reason our article has been rejected so far. It's up to readers to decide if they're more committed to data or to theory.

I won't criticize other excellent models and theories--they get lots of references. However, when you need a theory that carefully and simply fits the Keeling curve, read our article.

It shows CO2 removal of 17.6 Gt following Mt. Pinatubo, as you see clearly above. You also see that it's not related to aerosols or its cooling--because the Agung and El Chichon eruptions had similar amounts of aerosols and cooling--and no CO2 impact after a year. The article shows two other eruptions that caused CO2 removal, and many more that didn't. The CO2 removal eruptions all dumped their ash into areas with recurring downwelling eddies.

Best regards, and Happy New Year-
Peter

[Ken Caldeira]

I thought conventional wisdom was that the carbon effect of Pinatubo was mostly a land carbon effect, due to increased diffuse solar radiation stimulating the lower parts of forest canopies, and perhaps reduced plant respiration associated with cooling.

https://www.nature.com/articles/nature07949

I thought conventional wisdom was that the ocean carbon effects of Pinatubo was mostly increased solubility associated with cooling.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GB007513

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[Michael Hayes]

The volcanic SO2 injection into the atmosphere increased the Antarctic O3 hole rather quickly and significantly. Moreover, the resulting Polar Stratospheric Clouds that the SO2 injection created, over both the Antartic and Arctic regions as the SO2 went global, trapped significant heat in those regions while eroding the O3 layer. 

Knowingly warming both polar regions for any reason, through any means, would seem to move us toward a thermally equitable atmosphere, not away from it. The end goal of CDR would seem to involve avoiding thermally stagnant atmospheric condition, the poles need to stay as cold as possible. 

A Heinrich event, or the massive dumping of ice into the Artic Ocean and thus shutting down the AMOC, is likely well underway already. Why help it?

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[Peter Fiekowsky]

Ken-you’re correct in my experience. Conventional wisdom may be wrong.    It says that land plants absorbed the 17 Gt of CO2 due to increased diffuse illumination and decreased total sunlight. That’s the equivalent of 17 billion mature trees in one year. 

Besides the fact that such an effect should occur every time there’s aerosol cooling—but it doesn’t, and the fact that agronomy tells us that the 2% reduction in sunlight should result in a significant reduction, not increase in photosynthesis, and that most of any additional carbon would be leaves and seeds that only last a year, not decades as the data shows—suggests that conventional wisdom doesn’t fit the data. 

Sarmiento 1993 discussed OIF being the cause. 

Peter 

Sent from my iPhone

On Jan 2, 2026, at 6:41 PM, Michael Hayes <electro...@gmail.com> wrote:



The volcanic SO2 injection into the atmosphere increased the Antarctic O3 hole rather quickly and significantly. Moreover, the resulting Polar Stratospheric Clouds that the SO2 injection created, over both the Antartic and Arctic regions as the SO2 went global, trapped significant heat in those regions while eroding the O3 layer. 

Knowingly warming both polar regions for any reason, through any means, would seem to move us toward a thermally equitable atmosphere, not away from it. The end goal of CDR would seem to involve avoiding thermally stagnant atmospheric condition, the poles need to stay as cold as possible. 

A Heinrich event, or the massive dumping of ice into the Artic Ocean and thus shutting down the AMOC, is likely well underway already. Why help it?

On Fri, Jan 2, 2026, 4:16 PM Ken Caldeira <kcal...@carnegiescience.edu> wrote:

I thought conventional wisdom was that the carbon effect of Pinatubo was mostly a land carbon effect, due to increased diffuse solar radiation stimulating the lower parts of forest canopies, and perhaps reduced plant respiration associated with cooling.

https://www.nature.com/articles/nature07949

I thought conventional wisdom was that the ocean carbon effects of Pinatubo was mostly increased solubility associated with cooling.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GB007513

On Fri, Jan 2, 2026 at 1:37 PM pfieko <pfi...@gmail.com> wrote:

Tom- Thank you for pointing out the gap between the current literature and the Keeling curve. I believe I'm the leading proponent of Pinatubo CDR.

Here's the data, from our The Pinatubo CO2 pause suggests a rapidly testable path to multi-Gt mCDR (preprint): 

This Mauna Loa data directly from NOAA is explicitly clear about the removal of 2.25 ppm which showed no sign of coming back 14 years later (or 32 years later).

You might ask, "Why don't the budgets (models) fit the Mauna Loa data?" 

Probably because they never tried--I've not seen any that compared their model to the historical data as we do. Peer reviewed science is about getting the data to fit existing theory. If the data doesn't fit the theory, it's not science and doesn't get published. That's the given reason our article has been rejected so far. It's up to readers to decide if they're more committed to data or to theory.

I won't criticize other excellent models and theories--they get lots of references. However, when you need a theory that carefully and simply fits the Keeling curve, read our article.

It shows CO2 removal of 17.6 Gt following Mt. Pinatubo, as you see clearly above. You also see that it's not related to aerosols or its cooling--because the Agung and El Chichon eruptions had similar amounts of aerosols and cooling--and no CO2 impact after a year. The article shows two other eruptions that caused CO2 removal, and many more that didn't. The CO2 removal eruptions all dumped their ash into areas with recurring downwelling eddies.

Best regards, and Happy New Year-
Peter

On Friday, January 2, 2026 at 7:01:52 AM UTC-8 goreau wrote:

Some proponents of ocean fertilization claim that the Mount Pinatubo eruption somehow sucked large amounts of CO2 out of the atmosphere into the ocean, and that they can replicate these effects cheaply.

 

Such large carbon sinks in 1991 do not appear in global land or ocean CO2 budgets (below, from Friedlingstein et al., 2025), and the slowdown in CO2 increase that year may be as ephemeral or imaginary as the so-called “global warming hiatus”.

 

[Greg Rau]

Happy New Year all!

In an earlier life I was a 13C/12C expert and had a number of successes sorting out C cycling (e.g. here and here). So I've had an interest in what the Mauna Loa 13C/12C record might tell us about global CO2 sources and sinks.  For starters the record 1980-2016 looks like this:

d13C values get more negative as 13C/12C declines, and the precision of measurement is about +/-0.1o/oo. So, the progressive 13C-deletion seen iin the air CO2 record reflects the dominant effect of increasing, 13C-depleted, fossil CO2 emissions. After this, the annual variation is also quite large due to the strongly 13C-depleted (more negative d13C values) CO2 injected into the air from fossil fuel and from seasonaly varying 13C-depleted respiration CO2, countered by seasonally varying 12C-selective CO2 uptake (CDR) by land plants, e.g. for 1990 preceding Pinatubo:

So if there was a significant, unique perturbation to this cycle (e.g., Pinatubo) we miight expect a change in this 13C/12C vs pCO2 relationship during that time.  I don't see that there is, with the possible exception that the slopes of the annual relationships slightly decline and the correlations are a little higher:

While there is a kink evident in 1991-1993, I don't see that is significantly different to other kinks present at other times.  

The effect of enhanced bio ocean uptake on atmospheric 13C/12C CO2 is attenuated because marine photosynthesis does not directly consume CO2 from air;  the CO2 must first equilibrate with dissolve inorg C in the ocean, which then significantly dilutes and attenuates the otherwise significant effect of 12C-selective C uptake by phytoplankton. So, it would seem the record is inconclusive on the Pinatubo phytoplankton hypothesis. However, I don't claim that my analysis is exhaustive (or correct), just that someone needs to take a hard look at the 13C/12C in addition to CO2 in trying to understand the strength of global C sources and sinks during Pinatubo and elsewhere in the record. Get in touch if you have ideas here, though I don't have a lot of time to spend on this.

Greg

  

https://groups.google.com/d/msgid/CarbonDioxideRemoval/34FB8AD0-C9E7-404D-9C62-96F3D4B21FCB%40gmail.com

.

[Peter Fiekowsky]

Greg-

I appreciate and honor your deep analysis, although I'm not fluent in 12C / 13C analyses. Sarmiento (1993) (attached) did a similar analysis, including oxygen analysis and came to a similar uncertain conclusion. Phytoplankton are not proven to be the pathway. However they're not disproven, and no other pathway appears plausible given the data.

I studied the philosophy of science back in the '70s. Back then, we knew empirically that no hypothesis can be proven, although data can disprove one. I'm not sure if that grounding in science still holds in the peer reviewed literature. Also, back then we used Occam's razor to choose between competing explanations. 

Please let's assume the 1970's philosophy of science applies for this discussion--just for my benefit.

I think we mostly agree that the quality of future life on our planet depends to a degree on replicating the 2.25 ppm CO2 removal from 1992 and restoring as best we can the Holocene climate that got civilization where we are. There is no other pathway that can remove anywhere near that much CO2 quickly. Thus choosing pathway(s) to do it is a topic with great significance. It's more important than almost anything else I can think of.

So, I say, we need to find the one or two most likely pathways to replicate and optimize the Pinatubo CO2 pause.

As I claimed last week, there is no other plausible explanation on the table right now. In my white paper  (p7) I dismiss six other explanations on three bases: 1) they don't occur in similar eruptions (1963 and 1980), 2) because mathematically they can only account for maybe 0.1% of the observed CO2 loss, and 3) they don't account for the multi-decade removal (excepting the alkaline rock theory which I made up and haven't heard before).

Any one of those reasons should be sufficient to remove each of the six explanations.

My questions to you and the other revered senior scientists on this list:

1. After reading that section of my white paper, do you know of any viable alternative explanation for the Pinatubo Pause besides phytoplankton photosynthesis?

2. If you agree that phytoplankton is the only viable explanation on the table today, do you see any alternative to the hypothesis of downwelling eddies and maintaining enough iron to nourish cyanobacteria to fix nitrogen?

3. Even though Sarmiento (and Rau) aren't sure it was phytoplankton, Do you agree that Occam's razor tells us to focus on phytoplankton for this critical issue?

4. Are the rules of science different now (in the age of computer modeling) than when I was a student at MIT? That is, does a theory no longer need to apply to physical data as long as it applies to multiple computer models, especially Monte Carlo models?

Warmest regards and appreciation on this most important issue,

Peter

[Wil Burns]

Peter Fiekowsky: "Peer reviewed science is about getting the data to fit existing theory. If the data doesn't fit the theory, it's not science and doesn't get published. That's the given reason our article has been rejected so far. It's up to readers to decide if they're more committed to data or to theory."

So, if your hare-brained "research" doesn't get published, it's a grand conspiracy on the part of the scientific community to suppress your "truth." SMH. And, oh year, "Occam's Razor" should be our scientific lodestar. It would be funny if it wasn't so alarming that you're propagating this BS at the moment that the CDR community is trying to build its credibility. 

wil

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From: carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> on behalf of Peter Fiekowsky <pfi...@gmail.com>
Sent: Sunday, January 4, 2026 10:17 PM
To: Greg Rau <gh...@sbcglobal.net>
Cc: Michael Hayes <electro...@gmail.com>; Ken Caldeira <kcal...@carnegiescience.edu>; Carbon Dioxide Removal <carbondiox...@googlegroups.com>
Subject: Re: [CDR] Re: Pinatubo and CO2 sinks

 

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