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A K-Brief (aka. Knowledge Brief) is a series of visual models, each with an explanation that ties them together into a cohesive story that as briefly as possible explains what experts need to know to be able to contribute their knowledge to improve the K-Brief.


Actively Fertilizing Key Areas of the Ocean to Stabilize the Ocean Food Chain and (hopefully) Reduce Ocean Acidification and Global Warming

LEAD:  Brian Kennedy and the TCC Team

LAST EDITED:  2023-07-12 09:36

ABSTRACT:  Given we do not know how far we are from collapse of the Ocean Food Chain, and there are indications that collapse could occur in the next decade or two, we propose to pursue this partial Remedy that avoids the many knowledge gaps in a fuller Remedy (that more fully addresses all the root causes), but should stabilize the Ocean Food Chain, and could possibly do far more.

Preface on this separate Remedy K-Brief

Typically, Problem K-Briefs contain the Alternative Remedies designed to address the root causes identified by that Problem K-Brief. However, in some cases, a remedy is developed that can successfully alleviate or eliminate more than one Problem. Rather than document that redundantly in multiple Problem K-Briefs, we break such remedies out into a Remedy K-Brief that the multiple Problem K-Briefs can then refer to.

In this case, this Remedy K-Brief will clearly remedy the “How do we stop the collapse of our ocean food chain (web)?" Problem K-Brief and will at least to some degree remedy the "Will Achieving Net Zero CO2 Emissions Stop Global Warming at <1.5°C as Expected?“ Problem K-Brief. To what degree it will be an adequate remedy on its own and for how long is unclear. The many knowledge gaps in those Problem K-Briefs still need to be closed before that can be determined. But regardless of what is determined on that (regardless of the uncertainty that currently remains), this K-Brief intends to show that “success is assured”: that this Remedy will reliably counter the negative effects of the root causes at their current levels.

Again, this Remedy K-Brief is not directly addressing the root causes of the Problem K-Briefs — much work remains to be done on those. But rather, this Remedy K-Brief is working out a potential near-term remedy that can be focused on separately, now, in advance of full understanding being developed under those Problem K-Briefs.

Preface on establishing Operational “Success is Assured”

The Target Problem Remedied by This

A different Problem K-Brief digs into the potential reverse causation of that blue causal path: that the plankton declines that have been underway since the 1800's may in fact be a major cause of the increases in CO2 levels in our atmosphere and ultimately a major cause of global warming (which started a few decades after the plankton declines began).  Many knowledge gaps need to be closed to determine the level of that reverse causation (and that is the ongoing focus of that Problem K-Brief).

However, it is entirely possible that a Remedy that increases the plankton populations in order to stabilize the ocean food chain will also result in:

  • Increasing carbon sequestering to the ocean floor

  • Reducing evaporation rates by increasing the ocean's surface microlayer

  • Increasing cloud formation, cloud albedo (reflectivity), and cloud lifetime by generating dimethyl sulfide and otherwise altering the secondary marine aerosol to have more cloud condensation nuclei

And thus, this Remedy K-Brief may also be a partial or even substantial remedy to this secondary Problem K-Brief "Will Achieving Net Zero CO2 Emissions Stop Global Warming at <1.5°C as Expected?". And if so, then it may slow or even stop the ocean acidification that threatens the calcifying plankton populations (the blue path in the prior Causal Map).

The Secondary Problem (hopefully) Remedied by This

So, that second Map above is potentially a negative feedback loop from the blue nodes on the right side of the first Map above to the blue nodes on the left side of that first Map. Or to make that a bit more visual, rotating the second Map above by 180 degrees so it is flowing the reverse direction.  You can then see that the first Map (on bottom here) is the orange cloud that is showing the causes of the plankton declines in the second Map (reversed on top here) that are potentially the major causes of the CO2 and global warming effects that could become causes of future plankton declines in the first Map (on bottom here). A dangerous positive feedback loop.

Ideation Technique: Look to "Mother Nature"

When in need of innovative ideas to solve engineering problems, one very effective technique is to look at how "Mother Nature" solved similar problems, and see if similar can be applied to your problem. In the case of solving problems with nature itself, "Mother Nature"s solutions are almost surely the best source of ideas.

In this case, the winds and dust storms from arid lands often carry dust that gets deposited onto the ocean surface resulting in huge phytoplankton blooms. It has been determined that the causation there is due to the iron-rich dust fertilizing areas of the ocean where the lack of iron is the limiting nutrient for that phytoplankton growth. [source: UNEP (2020), Impacts of Sand and Dust Storms on Oceans: A Scientific Environmental Assessment for Policy Makers, United Nations Environment Programme, Nairobi, Kenya]

Similarly, volcanic eruptions have been shown to fertilize the oceans with iron resulting in huge phytoplankton growth. A 2008 eruption on the Aleutian islands resulted in large enough phytoplankton blooms that it resulted in a significant reduction in CO2 in the ocean water, and thus reduce ocean acidification. [source: B Langmann, K Zaksek, M Hort, Atmospheric distribution and removal of volcanic ash after the eruption of Kasatochi volcano: A regional model study, Environmental Science, Geology, Jan 2010]

So, "Mother Nature" has demonstrated a remedy to these Problems...

First, we need to make some room where that pink sub-Map node is — and then we need to break out the different nutrients that drive phytoplankton growth.

It might be tempting to measure those nutrients in grams of nutrient per liter of ocean. While that might work for instantaneous growth, what we want to establish is a continuous rate of growth, for which we will need to supply a continuous flow of nutrients. Practically, that might mean supplying a certain number of grams per liter of ocean per hour during the day, and perhaps much less at night. However, that's below the level of detail that we want to model here, so we will use units of "per day" and ignore the details of what needs to vary during the day. We can look at that when optimizing the "how", rather than this focus on the generic "what" that the solution needs to do.

Side Note: Addressing a Common Objection to Ocean Fertilization

Remedy Description

On the left side, we'll need to model the supply flow of those nutrients.  On the right side, we'll need to work out the required balance of nutrients to drive the phytoplankton growth rates.

The key complicating factor in the latter is modeling the competition for those nutrients between the desirable phytoplankton (the food for the rest of the ocean food chain) and the undesirable phytoplankton (that are either inedible or toxic to the existing ocean food chain). There would seem to be a lot of complex knowledge gaps to close in understanding the nutrient balance required to get the desirable phytoplankton to win that competition...

Mapping the Required Nutrients

Fortunately, "Mother Nature" makes this easy on us. It turns out that the most desirable subset of phytoplankton (Diatoms) naturally out-compete all the other phytoplankton microalgae as long as they have an adequate supply of nutrients.  In particular, Diatoms uniquely need silicate to form their shells, so silicate concentration tends to dictate Diatom growth competitively. One research paper shows that Diatoms will out-compete all other plankton for nitrate as long as they have enough silicate. [source: SR Smith, CL Dupont, JK McCarthy, et al, Evolution and regulation of nitrogen flux through compartmentalized metabolic networks in a marine diatom, Nat Commun 10, 4552 (2019)] Another paper shows that as long as the silicate concentration is above 2 umol/L, then Diatoms will dominate. [source: JK Egge, DL Aksnes, Silicate as regulating nutrient in phytoplankton competition, Mar Ecol Prog Ser. 83: 281–289 (1992)]

Diatoms Naturally Dominate

Given that, we can dramatically simplify our modeling by simply adding a rule (a limit) that we'll supply enough silicate; either more than is needed for the level of nitrogen, or enough to maintain the necessary concentration (2 umol/m^3 or perhaps safer 4 umol/m^3), or both. That rule is a simple added Relation between the available silicate and the available nitrogen (we'll use the light bulbs to mark what we added or changed to the Map in each step taken in this K-Brief).

With such a rule in place, then we no longer need to model the competition with other phytoplankton; or at least other microalgae — it may be that macroalgae is still an issue, since the papers do not assert Diatoms will out-compete macroalgae (that is a knowledge gap we need to close).

Diatoms have been shown to be adaptable to lower levels of nitrate and to lower levels of phosphate. [source: J.K. Egge, D.L. Aksnes, Silicate as regulating nutrient in phytoplankton competition, Mar Ecol Prog Ser 83: 281–289 (1992)] That would seem to complicate the modeling of the required nutrient levels. However, the way that adaptation works is that the Diatoms are able to absorb excess nitrates and phosphates while excess is available such that in later periods when there are lower levels, they can use the extra that they absorbed earlier.

In the end, though, Diatoms are made up of a specific ratio of carbon, oxygen, phosphorus, nitrogen, and silicate atoms. That ratio is called the Extended Redfield Ratio (extended to include silicate in addition to the rest which were identified by Redfield for phytoplankton in general).

Thus, for modeling a continuous operation where we are controlling those levels, we just need to target the Diatoms' ultimate long-term needs (what they consist of).  That is in terms of atoms, rather than mass, so we will do a simple conversion based on the molecular weight of each, and then compute the number of moles of the Extended Redfield Ratio that are available each day, based on the least available nutrient(s).

Diatoms are Adaptable (but in the long-run, it doesn't matter)

Mapping the Impact on Global Warming and Ocean Acidification

The dark green sub-Map far right above represents the impact that additional ocean food chain productivity will have on atmospheric CO2 levels and on global warming. In the secondary Problem K-Brief of this Remedy, we identified three major causal paths for that:

  • The additional plankton populations will sequester additional CO2 to the ocean floor.

  • The additional lipids in the surface microlayer will reduce evaporation and thus reduce the dominant greenhouse gas, reducing global warming.

  • The additional plankton will release dimethyl sulfide and otherwise alter the secondary marine aerosols increasing cloud formation which has a net cooling effect.

Those three causal paths have been added below, connecting to new Ocean Acidification and Global Warming nodes (marked with flags since those are effectively connected to the flagged nodes on the left side of this Map, forming a feedback loop).

Macroalgae Competition?

As mentioned earlier, macroalgae competition may still be an issue; particularly in the HNHC areas where there is already large established populations of macroalgae. How much of an issue, if any, is a knowledge gap that needs to be closed. Whether the macroalgae that is an issue has different nutrient requirements that need to be modeled separately, or whether it is a close enough match that we can keep it simple is thus also unclear. Until we know more, we will keep it simple. But we do want to model it such that (a) it is not forgotten and (b) we have a knob to use to introduce different levels of uncertainty such that we can see the impact of that uncertainty on our results.

So, we have chosen to model that by simply having the competition consume some portion of the Extended Redfield Ratio moles that would otherwise be available.

Plankton Productivity is Not in Moles

The dark green sub-Map that remains above is now just the CO2 Sequestering. The Diatoms that get consumed by zooplankton that then convert O2 back to CO2 are arguably not really sequestering anything. The zooplankton that get eaten by fish that get pulled out the ocean by fisheries arguably are not sequestering any CO2.  However, while alive, the zooplankton and fish generate a lot of fecal matter that contains the carbon from the Diatoms and sinks to the ocean floor. Further, the unconsumed plankton and fish that die and sink to the ocean floor are also sequestering carbon for potentially thousands of years. To model that, we need to separate out the biomass that is unconsumed or excreted as fecal matter from the consumed and used biomass. We have added that below.

Iron needs vary widely relative to Redfield Ratio

Mapping the Flow of Nutrients

Next we'll work the left side of this Map, working back from the nutrients that are required by the Diatoms to the flow of nutrients available in that area of the ocean.

The basic premise of this Remedy is to grow Diatoms in the HNLC parts of the ocean where there is already a stable flow of most of the needed nutrients. Often just iron and silicate need be added.

However, each area of the ocean may have different levels of nutrients and different upwelling flows. And those upwelling flows may be declining as global warming is shutting down many of the traditional currents. So, the first thing we need to add to our Map is the existing flows and nutrients in that area of the ocean, colored ocean blue. (Note we recolored the ammonium, nitrate, and sunlight availability nodes to ocean blue as well since they too are parameters of that area of the ocean.)

Ammonium can block Nitrate Uptake

The growing zooplankton population can greatly boost the upwelling flow bring nutrients from the ocean below to the surface for the Diatoms. But mechanical boosting will also likely be needed in many areas.

For simplicity in this model, we will not be modeling the mechanical "how" to create that additional flow, but rather just what percentage boost will be needed.

Note that the upwelling flow has been show to have a direct impact on Diatom productivity, beyond just the supply of nutrients. [source: I Orefice, M Musella, A Smerilli, et al, Role of nutrient concentrations and water movement on diatom’s productivity in culture, Sci Rep 9, 1479 (2019)] So, there will likely be some optimum flow level needed for the Diatom productivity, and that flow will give a certain level of boosted nutrients.

Finally, note that the use of upwelling flow not only reduces the required fertilization levels, it more closely mimics the state of the ocean pre-industrialization, when huge populations of whales, fish, and zooplankton and the larger pre-warming ocean currents all contributed to such upwelling flows.

Knowledge Gap: Other Micro-Nutrient Needs?

Beyond iron, there are other micro-nutrients, including vitamins and trace minerals, needed by photosynthesis (and potentially other Diatom processes). Many studies have shown tremendous Diatom blooms from just adding iron, possibly implying that the other micro-nutrients tend to be in adequate supply. However, it is not clear that will always be the case, thus there may be other micro-nutrients that need to be monitored and supplied. That is a knowledge gap that needs to be closed. A cloud for that was also added in the upper left of the prior Causal Map.

Mapping the Impact on CO2 Sequestering

Once the boosted upwelling rate is known such that the boosted flow of nutrients is known, then additional nutrients will need to be added to get to the ratios required by the right side of this Map.

Beyond those intentional adders, there may be fertilizer runoff adding to the Nitrogen and Phosphorus numbers.

Further, note that added nutrients can be in many forms, and those forms tend to have different rates of sinking. To avoid needing to model complex fluid flow on that, we will simply require that the maximum sink rate of the infused nutrients be less than the boosted upwelling rate.

Finally, note that as the Diatom Biomass Productivity ramps up, the Zooplankton and Fish and Whale Biomass Productivity should also ramp up. And with those, the feedback loops increasing the nutrient flow from the depths to the surface should also increase (the purple sub-Maps). Ideally, as the zooplankton and whale populations return to normal, the flows of nutrients may be fully restored such that this remedy is no longer needed at all. But in the meantime, there may be need to gradually ramp down the induced upwelling rates and/or the infused nutrient rates. And the dams are not going away, so there may always need to be silicate fertilization to reverse the effects of the dams.

We computed how Ocean Acidification and Global Warming are effected on the right, and flagged that they feedback in on the left, but in the prior Map those nodes were just floating on the left edge of the Map. In this next Map we hook them up, mostly along the bottom of the Map.

One additional add: it has been pointed out that mycoplankton (fungi) may play a role in nutrient availability. We simply capture that as a knowledge gap (the lighter orange sub-Map).

Boosting the Flow of Nutrients

Note further that increased Fishery Productivity will enable human dietary protein needs to be met with more fish and less beef and lamb. Fish has a significantly smaller carbon footprint (6kg) than lamb (19.9kg), which is significantly smaller than beef (35.5kg) (see the chart below [source: United Nations, Food and Climate Change: Healthy diets for a healthier planet]). Thus, the additional Fishery Productivity should result in further reductions in ocean acidification and global warming, beyond just the additional direct carbon sequestering from the unconsumed and fecal ocean biomass. An additional sub-Map shape was added, far right of the Causal Map above, to capture that for future mapping.

Mapping the Operational Costs

Finally, we need to tally up the operational costs, which will always be a key trade-off. In this case, the infused nutrients have cost and the mechanical boosting of the upwelling rate will have cost. Of course, there are likely many more operational costs in a practical implementation of this, but here we are just mapping out the operational costs that are inherent to this generic solution.

All the cost-related nodes are colored light green.

Infusing Nutrients to the Required Ratios

Summary of Knowledge Gaps to be Closed

Adding in the Effects of CO2 and Global Warming

In typical corporate scenarios, this K-Brief would have a "Plan to Close the Knowledge Gaps" block as the owner typically has significant financial incentive to close those knowledge gaps before committing to decisions.

In this scenario, we have no budget nor authority to get the ocean experts to do the necessary experiments or tests or data gathering and analysis to close these knowledge gaps. We can only make visible the knowledge gaps and hope that those capable of closing them will do so.

Here is a listing of the knowledge gaps identified in this Remedy K-Brief:

  • How close are we to the Allee Effect leading to the collapse of the ocean food chain? (And therefore, what is the required timeline for this Remedy to be put into action?)

  • Is it sufficient to limit the ratio of silicate to nitrate to ensure Diatoms will out-compete all forms of microalgae and cyanobacteria? Or will we also need to limit the silicate concentration level? Or is more needed beyond those two limits?

  • Can we assume Diatoms will similarly out-compete or otherwise be unaffected by undesirable macroalgae? Or will we need to deal with that macroalgae? (This is of particular concern where significant macroalgae populations already exist.)

  • Are there any upper limits on Diatom productivity based on available surface area? Or will nutrient limits always limit growth prior to using up the surface area?

  • What do we need to know about an area of the ocean in order to determine what the photosynthesis needs will be that then drive the iron requirements that determine the Carbon to Iron ratio that needs to be maintained?

  • In HNLC areas of the ocean, could ammonium levels impact nitrate uptake resulting in lack of nitrogen availability despite the extra nitrogen in the ammonium (paradoxically)? Or is that problem not possible in the open ocean?

  • What are the different sink rates of different forms of the nutrients?

  • What are the differences in availability or usability by the Diatoms of different forms of the nutrients?

  • Are there vitamins or other nutrients that may not be in adequate supply and thus need to be modeled (and supplied)?

  • Is there need to tie vitamins or other nutrients to silicate such that they are more available to Diatoms than to other phytoplankton?

  • Given the number of moles of Extended Redfield Ratio units, how do we compute the resulting biomass productivity in grams? Is that a known ratio or formula?

  • What is the mathematical impact of the upwelling flow (besides the nutrient increases) on the Diatom Biomass Productivity?

  • Given a biomass productivity of Diatoms, how do we compute the biomass productivity of the zooplankton that feeds on those Diatoms? Are there additional characteristics of different ocean areas that will factor into that? Will we need to do anything to enhance that?

  • Given a biomass productivity of zooplankton, how do we compute the boost to the upwelling rate? Also, will that have an impact on the available nutrient flow? And does mycoplankton (fungi) play a role in nutrient availability that needs to be mapped out here to properly optimize this Remedy?

  • Given biomass productivity of both Diatoms and zooplankton, how do we compute the biomass productivity of the fish and the fishery productivity?

  • Can we map fishery productivity to operational revenue that can be used to offset the operational costs here?

  • Given the deltas between those biomass productivities and the fishery productivity, how do we compute the level of carbon sequestering to the ocean floor? (The IPCC has estimated the carbon sequestering of today's oceans; can we linearly ramp up that based on the increases in the ocean food chain populations?)

  • What is the contribution of Diatoms to the total amount of organic carbon in the oceans and sea beds? And how much organic carbon is currently contained in the oceans and sea beds?

  • Given a biomass productivity of Diatoms, what is the lipid production and other impacts to the surface microlayer? And based on that, what is the impact on the evaporation rates, and in turn the impact on global warming due to reduced water vapor (the primary greenhouse gas)?

  • Given a biomass productivity of Diatoms, what is the dimethyl sulfide production and other impacts to Secondary Marine Aerosols? And based on that, what is the impact on cloud formation, and in turn the impact on global warming due to increased clouds and increased reflection of the incoming sunlight/heat?

  • Are there limits on iron infusion or iron concentrations based on it being considered an ocean pollutant? And if so, can those regulations be changed? (Note that prior to industrialized whaling, the whale populations brought 10X the iron to the surface as today; so, iron fertilization is really just restoring prior iron levels. Closing knowledge gaps on those historical levels may be the justification needed to close the knowledge gaps on the regulations.)

  • What is the relative impact of Diatom productivity on eutrophication, harmful algal blooms, hypoxia, et cetera?

  • Are there negative effects of excess plankton that need to be captured as upper limits?

  • Are there nutrients that can be added to either reduce ocean acidification or to prevent undersaturation of calcite and/or aragonite?

  • How will Methane Hydrate Lock be improved/protected by this Remedy?

The Problem K-Brief "How do we stop the collapse of our ocean food chain (web)?" built up the following Causal Map of the problem, which mostly consists of knowledge gaps that need to be closed (the focus of that ongoing Problem K-Brief).

However, one of the key knowledge gaps that remains is how soon the population declines will result (due to the Allee Effect) in the collapse of the ocean food chain (web). Given that could be tomorrow, we have urgent need to stabilize the ocean food chain today.

That is the primary goal of this Remedy K-Brief.

One complicating issue is the causal path in blue below: ongoing increases in CO2 and global warming will lead to ongoing acidification of the ocean, which will eventually lead to undersaturation of calcite and aragonite which will then lead to declines in calcifying plankton, in particular Diatoms. To address that, it becomes important to look at a secondary Problem K-Brief...

This Remedy K-Brief does not get into designing or optimizing how the solution will be constructed.  We are working on that “how” with engineers that know what will be required for that. Optimizing that is not the purpose of this Remedy K-Brief.

Rather, this Remedy K-Brief is focused on developing out “what” this remedy needs to do to alleviate the Problems it is trying to address.  The goal is to establish scientific consensus that this Remedy, however it is put into action, will indeed alleviate the identified Problems, and at what operational cost. So, the Causal Maps developed out here are focused only on the operational behaviors and the causal impacts of those, both on the cost side and the benefits side.

With those validated here, then the operational models of specific solutions can be plugged into this already-validated model to determine the operational costs & benefits of the specific solution, enabling comparison and optimization of different specific solutions.

What is not included are the construction costs and any other upfront investment costs, nor the elements (such as long-term reliability and durability) that trade-off with those upfront costs. Those are being worked separately with potential solution providers.

The goal of this Remedy K-Brief is to get as many experts as needed efficiently collaborating on this operational model of a potential Remedy to a number of global Problems.  If you have such expertise and are willing to point out anything that should be corrected or improved in this Remedy K-Brief, please contact us at SaveOurOceans@TargetedConvergence.Com.

Vast areas of the ocean are essentially deserts devoid of much ocean life, but actually fairly high in some (but not all) of the needed nutrients. These are typically labeled High-Nutrient Low-Chlorophyll (HNLC) areas of the ocean. These areas of the ocean tend to be far from the coastal regions, and thus far from most of the sources of pollution, toxins, and microplastics that are the root causes identified by the target Problem K-Brief.

Further, there are High-Nutrient High-Chlorophyll (HNHC) areas of the ocean that are predominately filled with undesirable Harmful Algae Blooms (HAB) due to the wrong balance of nutrients, in particular the lack of silicate which prevents the growth of the more desirable Diatoms.One cause of this is the damming of rivers reducing the movement of silicate-rich silt down the rivers and into the ocean. These HABs are not consumed by the zooplankton or fish, so do not contribute to the ocean food chain, but rather consume the nutrients needed by the food chain.

We propose to remedy the two Problem K-Briefs by actively establishing the right balance of nutrients in the high-nutrient areas (both HNLC and imbalanced HNHC areas) of the ocean in order to grow the desirable phytoplankton that are then consumed by the zooplankton and fish, stabilizing the ocean food chain, and (hopefully) sequestering substantial carbon to the ocean floor and thereby reducing ocean acidification and reducing global warming.

Note that this Remedy is not reducing or eliminating the root causes of the target Problem K-Brief, but rather avoiding them or directly reversing them. By directly feeding areas low in silicate due to human-caused reduction in silicate flow, this remedy is reversing the effect (though not addressing the root causes, such as the damming of rivers). By operating in HNLC areas outside of the coastal regions, this remedy avoids much of the human-caused pollution, toxins, and microplastics, but effectively reverses the effects of that pollution by restoring the plankton populations to their pre-Industrialization levels, though further from the coastlines. Thus, that target Problem K-Brief should continue to develop knowledge of and remedies for those root causes it identifies. However, the more urgent need is to avoid the collapse of the ocean food chain, and by focusing on filling the high-nutrient areas of the ocean with that ocean food chain, we can stabilize it, potentially indefinitely.

Restating that more visually, this Remedy K-Brief will focus in on the central portion of the target Problem K-Brief's Causal Map, as shown below, by designing a remedy that actively maintains the nutrient balance (the pink sub-Map) where it needs to be in key areas of the ocean. The rest of this Remedy K-Brief will focus on fleshing out the details hidden in that pink sub-Map.

It will also address enough of the reverse causation from the secondary Problem K-Brief (the dark green sub-Map in this Map) to address the changes to the ocean currents due to global warming and the acidification caused by the combination of global warming and higher atmospheric CO2 levels. However, given that is not needed to justify this Remedy (stabilizing the ocean food chain is adequate justification), we will not be fleshing out the details and broader effects of the green sub-Map, but rather just marking those feedback loops with the blue flags to keep in mind the negative feedback loops to be monitored for ongoing stability of the remedy in the face of continued CO2 Emissions or continued global warming (if those continue).

With the addition of the separate sources of nitrogen (ammonium and nitrate), it should be noted that it is possible for the presence of moderate levels of ammonium to block nitrate uptake and result in inadequate supply of nitrogen. It has been observed that effect is proportional to the so-called f-ratio (the ratio of ammonium uptake to the sum of ammonium and nitrate uptakes). It is not clear that this will be an issue in the open oceans, but if it impacts the iron requirements, it could very well impact the nitrogen requirements as well. And in fact, this may be one of the key negative effects of fertilizer runoff that has been reducing our plankton populations.  [source: R Dugdale, F Wilkerson, AE Parker, The "Ammonium Paradox": a summary of more than a decade of research into phytoplankton processes and nitrogen relationships in the northern San Francisco estuary, Nov 2016 draft]

Digging into the Evaporation and Cloud Formation Sub-Maps

In the lower right of the above Causal Map are a number of sub-Map (cloud) shapes hiding the details of how the increased Diatom Biomass Productivity will impact evaporation and cloud cover that ultimately affect global warming. We have isolated those out here:

There have been attempts to handle the iron nutrient needs of Diatoms via a further-extended Redfield Ratio. However, those attempts have resulted in a widely uncertain ratio for iron — by orders of magnitude.

Why? Because the iron needs are not a function of the Diatoms' molecular content, but rather due to the needs of the photosynthesis process. And if ammonium (NH4) is available as the nitrogen source, less energy is required than if nitrate (NO3) must be used. The more energy-limited the Diatoms are, the more iron gets used. So, the iron requirements vary with the level of sunlight and with whether photosynthesis is based on NH4 or NO3. [source: NM Price, The elemental stoichiometry and composition of an iron-limited diatom, Limnol. Oceanogr., 50(4), 2005, 1159–1171] An Iron Stress Index has been suggested to model the iron dependency. [source: IY Fung, et al, Iron supply and demand in the upper ocean, Global Biogeochemical Cycles, 14(1), 281-295, Mar 2000]

Expanding out the two sub-Map shapes on the right above, we can get some insight into the cause & effect of Diatom Biomass on cloud formation and global warming. Working from the left in the Map below, the production of lipids and similar by the Diatoms into the surface microlayer along with the production of dimethyl sulfide combine to change the size and contents of the secondary marine aerosol particles that serve as both Cloud Condensation Nuclei (CCN) and as Ice Nucleating Particles. The surface microlayer also reduces evaporation. With the reduced overall volume of water in the atmosphere and the increased number of CCN, you get a higher number of much smaller Cloud Droplets, which results in higher reflection and refraction of incoming short-wave light (increased albedo of the clouds). Further, the smaller average Cloud Droplet radius results in clouds that remain clouds much longer before they precipitate. Net: more clouds form and those clouds stick around longer, resulting in a double-impact for much higher Cloud Cover Fraction. And that higher Cloud Cover Fraction has higher albedo (reflectivity)... making that a triple impact on the earth's albedo relative to the albedo of the ocean surface, resulting in a reduction in the heat absorbed by the earth (much more is reflected away). Further, the reduced evaporation also means less of the dominant greenhouse gas (water vapor), further reducing the heat absorbed. That reduced heat absorbed gets translated into a reduction in global warming based on the Equilibrium Climate Sensitivity which the IPCC currently estimates at 1.2°C per 1 Watt per square meter of additional heat absorbed (or not).

Unintended Consequences

Plankton and Fish productivity are not typically measured or reported in molar amounts. Rather, the typical measure is mass per year; or if per unit of ocean, then mass per volume per year. In our case, designing for a continuous operation, we will use "per day" numbers, as we did with the nutrients: so, g/L/d.  So, here we add a simple relation to convert from the molar availability to the biomass (based on the biomass per available mole of the Extended Redfield Ratio for Diatoms).  And then that biomass productivity will drive similar biomass productivity for zooplankton and for fish.

Example: Some Diatoms produce a Toxin

Next Steps for this Remedy K-Brief

Flip side: We already have Unintended Consequences that this will Undo!

Note that we have not yet established that “success is assured” for this Remedy K-Brief. We need to close the many knowledge gaps listed above, at least enough that we can mathematically model that the solution succeeds despite the remaining uncertainty. Thus, we solicit additional expertise and additional experimentation and testing to help us close those knowledge gaps. As that knowledge is provided to us, we will update this K-Brief until such time as we have developed scientific consensus that “success is assured”.

Note also that this is just establishing that operationally “success is assured”, without considering the most optimal ways to construct a particular solution capable of performing this operationally. We are working on that with potential suppliers of such particular solutions. But in the meantime we would like to collaborate with ocean experts to establish that “success is assured” for this generic operational model.

If you have expertise in any of the areas needed to establish “success is assured” (even if those are areas that we have yet to identify we need), and are willing to point out anything that should be corrected or improved in this K-Brief, then please contact us at SaveOurOceans@TargetedConvergence.Com.

Although it is tempting to add a simple knowledge gap "What are the unintended consequences that need to be prevented?", that is somewhat "wishful thinking" because the whole point with "unintended consequences" is there may be things we don't think of... the "unknown unknowns".  The ongoing Mapping process above will help us identify "unknown unknowns" over time, but in the end there is always possibility that we missed some.

So, it is important that we design the remedy with two key ingredients:

  1. Appropriate testing and monitoring to detect any unintended consequences early.

  2. Appropriate controls to allow the remedy to be quickly turned off and even reversed if undesirable unintended consequences are ever detected.


For now, we will keep it simple and focus on closing the knowledge gaps that allow us to establish what is needed for an effective remedy. But we have added this block as a reminder that we will need to design for unintended consequences emerging before we can declare "success is assured" for this Remedy.

The Diatom genus Pseudonitzschia can produce domoic acid which is a neurotoxin that can have detrimental effects on the ocean food chain. [source: CG Trick, BD Bill, WP Cochlan, ML Wells, VL Trainer, LD Pickell, Iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas, Proc Natl Acad Sci U S A, 2010 Mar 30, 107(13):5887-92]

Given that, a specific solution should either prevent that genus of Diatom or should monitor for it and/or for the domoic acid. If the quantities of those remain below the levels of normal natural ecosystems, then it is presumably not a problem. However, if the quantities exceed normal levels, then there should be a designed response to deal with that unintended consequence. Given the knowledge gaps associated, the best response may be testing and experimentation to determine whether those levels represent a problem, and to determine if there are approaches that can effectively neutralize the toxin or reduce the growth of that genus of Diatoms. But ultimately, the response may need to shutdown the specific solution.

There has been some resistance in the past to leveraging the oceans to sequester carbon on the basis that we want to avoid damaging our oceans. While we salute that sentiment, it should be noted that we've already damaged our oceans tremendously, starting long before global warming. And in fact, increased CO2 and global warming might be already-existing unintended consequences of the pollution and over-fishing that is killing our ocean food chain.

So, this Remedy can be seen as reversing the undesirable changes we've already caused to the ocean, thereby reducing the many Unintended Consequences that we already have (and may not realize). Enacting this Remedy is in all likelihood less risky to our oceans than not enacting it. In particular, fertilization with iron is just reversing the loss of iron from the loss of whales; and fertilization with silicate is just reversing the loss of silicate from the damming of rivers.

However, that said, we should invest heavily in closing the knowledge gaps and in collaborating to uncover potential unintended consequences; but we shouldn't let the fear of unknowns stop us from fixing the known problems that we already know could have devastating further consequences in the near future.

We are not the first to propose some form of ocean fertilization; in particular, it is one of the more promising approaches to Carbon Dioxide Removal (CDR). A very common objection is that we should not risk damaging our ocean ecosystems by using them for CDR. And while we generally would applaud that sentiment, it is ignoring the fact that we have already damaged our ocean ecosystems and ocean fertilization is putting them back closer to how we found them.

The damming of our rivers has reduced the flow of silt into our oceans which dramatically reduces the natural silicate fertilization, resulting in a shift from diatoms to Harmful Algae Blooms (HABs). [source: V Ittekkot, L Rahm, DP Swaney, C Humborg, Perturbed Silicon Cycle Discussed, Eos, v81 n18, 2000 May 2]  The millions of giant whales that populated our oceans before industrial whaling brought more than 12 Mt of iron per year to the ocean surface in the southern ocean alone. [source: MS Savoca, MF Czapanskiy, SR Kahane-Rapport, et al, Baleen whale prey consumption based on high-resolution foraging measurements, Nature 599, 85–90, 2021]  Beyond just iron, it has been shown that, in the Gulf of Maine, whales bring nutrients from the depths where they feed to the surface at a level greater than the flow of nutrients from all the rivers combined. [source: J Roman, JJ McCarthy, The whale pump: Marine mammals enhance primary productivity in a coastal basin, PLoS ONE, 2010; 5 (10): e13255]  All of that natural fertilization has been halted by humans. We need to restore it.

So, again, "Mother Nature" has demonstrated a remedy to these Problems, and that remedy is just putting the oceans back the way we found them prior to industrialization, back the way "Mother Nature" intended...

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