Introducing LOF: Localized ocean fertilization is not OIF....It’s vastly better
Peter Fiekowsky
I apologize to those who have seen the graph recently. This is a more complete discussion.
This new piece explains how nature removed almost 20 Gt CO2 in a year and a half after the 1991 Mt. Pinatubo eruption. This defies published OIF models that say only about 1 Gt CO2 can be removed in a year, using all the oceans.
The refined process is Localized ocean fertilization, (LOF). It is based on new analysis of CO2 after volcanic eruptions and CO2 satellite data from NASA's OCO-2 .
“You can have your own opinions, but you can’t have your own data.” - Ken Buesseler
“When the facts change, I change my mind - what do you do, sir?” - John Maynard Keynes
The removal data is clear in the Keeling Curve, Mauna Loa CO2 data (blue), compared to a simple model (green).
Fig. 2. The lower panel compares actual CO2 levels measured at Mauna Loa (solid blue) with expected CO2 levels (dotted green). The discrepancy indicates long-term removal of 2.25 ppm of CO2. The upper panel shows that two eruptions of similar size and global cooling impact, Agung (1963) and El Chichon (1983) led to no persistent CO2 removal. (from Fiekowsky and Burnham, 2025)
The key points, for this audience, are:
Most CO2 removal occurs in downwelling eddies. Smetacek reported about 50% of biocarbon removal, compared to typically 1-2% removal using sinking diatoms in non-downwelling regions. Data analysis in process from NASA’s OCO-2 CO2 observatory satellite confirms this.
Maintaining higher iron levels allows growth of nitrogen fixing phytoplankton (cyanobacteria). This provides a continuing supply of critical nitrates. Sophie Bonnet writes about this
Other explanations for the 1992 CO2 removal, such as increased diffuse light and 0.5C lower temperature increasing photosynthesis and CO2 solubility, don’t fit the historical CO2 data. The other two large eruptions (Bali and El Chichon) that cooled the planet similarly, don’t show any significant CO2 impact.
chris....@btinternet.com
Peter,
There are quite a number of problems with your Localized Ocean Fertilization (LOF) proposal, most of which you are already aware of (e.g., see my email response to you of 12 September 2023). In my attached response I will primarily focus on your estimate of the CO2 decline after the Mt Pinatubo eruption and make some short comments about a few other points.
The conclusion of my response is:
There was no large-scale ocean fertilization event in the South China Sea in 1992-1993 following the Mt. Pinatubo eruption in June 1991 as:
- Your calculation of the estimated CO2 removal is based on a flawed methodology that greatly exaggerates the decline in atmospheric CO2 and is thus invalid.
- The real removal of atmospheric CO2 in that period was due to terrestrial uptake, mainly in North America, coupled with a reduction in emissions that together explain the actual decline in atmospheric CO2.
- Consequently, there is no need to invoke speculative Local Ocean Fertilization to explain the decline in atmospheric CO2 following the Mt Pinatubo eruption.
Best wishes
Chris.
From: carbondiox...@googlegroups.com <carbondiox...@googlegroups.com> On Behalf Of Peter Fiekowsky
Sent: 11 January 2026 15:15
To: Carbon Dioxide Removal <CarbonDiox...@googlegroups.com>
Cc: Ken O Buesseler <kbues...@whoi.edu>; Fei Chai <fcha...@gmail.com>; Victor Smetacek <Victor....@awi.de>; Seth John <seth...@usc.edu>; Carl Page <carl...@gmail.com>; John Preston <Pre...@temcapital.com>
Subject: [CDR] Introducing LOF: Localized ocean fertilization is not OIF....It’s vastly better
My new substack is out: Localized ocean fertilization is not OIF....It’s vastly better
I apologize to those who have seen the graph recently. This is a more complete discussion.
This new piece explains how nature removed almost 20 Gt CO2 in a year and a half after the 1991 Mt. Pinatubo eruption. This defies published OIF models that say only about 1 Gt CO2 can be removed in a year, using all the oceans.
The refined process is Localized ocean fertilization, (LOF). It is based on new analysis of CO2 after volcanic eruptions and CO2 satellite data from NASA's OCO-2 .
“You can have your own opinions, but you can’t have your own data.” - Ken Buesseler
“When the facts change, I change my mind - what do you do, sir?” - John Maynard Keynes
The removal data is clear in the Keeling Curve, Mauna Loa CO2 data (blue), compared to a simple model (green).
Fig. 2. The lower panel compares actual CO2 levels measured at Mauna Loa (solid blue) with expected CO2 levels (dotted green). The discrepancy indicates long-term removal of 2.25 ppm of CO2. The upper panel shows that two eruptions of similar size and global cooling impact, Agung (1963) and El Chichon (1983) led to no persistent CO2 removal. (from Fiekowsky and Burnham, 2025)
The key points, for this audience, are:
- Most CO2 removal occurs in downwelling eddies. Smetacek reported about 50% of biocarbon removal, compared to typically 1-2% removal using sinking diatoms in non-downwelling regions. Data analysis in process from NASA’s OCO-2 CO2 observatory satellite confirms this.
- Maintaining higher iron levels allows growth of nitrogen fixing phytoplankton (cyanobacteria). This provides a continuing supply of critical nitrates. Sophie Bonnet writes about this
- Other explanations for the 1992 CO2 removal, such as increased diffuse light and 0.5C lower temperature increasing photosynthesis and CO2 solubility, don’t fit the historical CO2 data. The other two large eruptions (Bali and El Chichon) that cooled the planet similarly, don’t show any significant CO2 impact.
I welcome feedback, negative and positive, while we prepare a paper for peer review.
Please share this in your communities. It's important.
Thank you-
Peter
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Ken Buesseler
Spurred on by Chris today, here are my thoughts on this issue. Ken
Hi Peter et al.
Here is some feedback as requested on your latest blog on Pinatubo and ocean iron fertilization (OIF) and its outsized impact on atmospheric carbon dioxide. Bottom line is there are simply not enough nutrients nor phytoplankton to support your claims.
Let’s take a moment to consider the ocean’s biological carbon pump (BCP) and the opinion that past events (1992 Pinatubo eruption) or purposeful ocean iron fertilization could conceivably remove close to 20 Gt CO2-eq (one Gt = 1 billion tonnes) of atmospheric CO2, by processes that take place in only 1/1000th of the area of the ocean. The latest incarnation of this claim invokes nitrogen fixers and downwelling eddies to act as conduits to fast track organic carbon flow to the ocean depths.
There are many published papers about how the Pinatubo eruption and subsequent reduction of atmospheric CO2, need not involve marine phytoplankton at all (e.g. McKinley et al.). This claim to the contrary requires considering ocean productivity, which depends upon sunlight and nutrients, and scaling to regional and global impacts.
To grow, phytoplankton requires not just iron and any nitrogen they can source from N2 fixation, but also phosphorus and other essential micronutrients. Drawing on Alfred Redfield’s seminal ratio of phytoplankton C and major nutrients in the ocean- C:N:P = 106:16:1, and even though the Redfield ratio can vary by a factor of two or more under some circumstances, there is no way to support a 20 Gt BCP without 1000’s of times more P supply than in the surface ocean For example, assuming that open ocean surface waters contain 0.01-0.05 µmol P per liter for a 50 m photic zone in 1/1000th of the ocean area, then one falls many orders of magnitude short of P needed to support of 20 Gt CO2 removal by.
Even if there were enough P available for phytoplankton to do this, how would this compare to the global range of phytoplankton biomass (0.1-1 Gt C) and net productivity rates (50-60 Gt C/yr). All together, these phytoplankton and marine food webs support a global BCP that is on order 5-12 Gt C/yr (19-45 Gt CO2-eq). So how can one claim that in only 1/1000th of the ocean, this volcanic event was of similar scale?
Peter Fiekowsky has started attributing a quote to me that I used at COP30, which I want to correctly attribute to Daniel Patrick Moynahan- “You are entitled to your opinion. But you are not entitled to your own facts”.
You can have an opinion of a 20 Gt CO2 Pinatubo based OIF ocean sink, and claim it can be done in 1/1000th of the ocean, but you need to back that up with an answer to where do all of these marine phytoplankton come from, or more fundamentally where do all the nutrients come from? That’s at the crux of this opinion vs fact-based assessment of the scale responsible OIF might contribute to marine CO2 removal (on order single Gt CO2/yr).
Yes, the BCP can be responsive to iron, and volcanic eruptions release iron, but there are physical limits and here, facts matter. Call it by a new name, “localized” OIF, and invoke downwelling eddies, or not. But it’s an opinion and not a fact, if it’s not supported by a simple mass balance for all the nutrients and massive phytoplankton C growth needed to invoke OIF as the cause. Grossly exaggerating OIF’s impacts only erodes the public trust. We don’t have to over promise to consider OIF as one of several marine carbon dioxide removal approaches that deserves further study. Beliefs or opinions are best kept out of this.
Thanks for your consideration.
Ken Buesseler
Emeritus Research Scholar, Woods Hole Oceanographic Institution
http://cafethorium.whoi.edu @cafethorium.bsky.social
Director, Center for Marine and Environmental Radioactivity
Executive Director, Exploring Ocean Iron Solutions
https://oceaniron.org/ @exois-oceaniron.bsky.social
