I’ve been following this research since the 1990s. My recollection is that a consensus emerged that it is less effective than originally hypothesized and there are some adverse side effects that would be difficult to manage. This is why it fell out of favor.

As I recall, while it does cause significant blooms in the areas that you seed, it also induces nutrient depletion in other regions, suppressing growth there and potentially damaging ecosystems that developed around the natural nutrient gradient. It became apparent that the “free lunch” wasn’t actually free and it was mostly just rearranging where things grew based on the interaction of various nutrient gradients. The net effect is therefore much smaller than originally thought and there is a risk that it inadvertently reduces the output of important fisheries due to complex oceanic chemistry interactions that are not fully understood.

I don’t think much has changed with respect to our understanding of it. It is currently filed under “probably a bad idea” as far as I know. But that’s why we do the science.

How does it cause depletion in other areas?

FWIW, I think the danger of excessive blooms is overstated. Most of the ocean is a desert nutritionally.

The flow and distribution of nutrients in the ocean follow weak gradients from their underlying sources in a kind of thermodynamic equilibrium. Some areas will have nutrient excesses based on geography, geochemistry, and limitations on consumption rate due to dependencies on other nutrients.

If iron is the rate limiting ingredient, then when you seed an area with iron a bunch of other nutrients are consumed in the process that currently are not being consumed. This changes the chemical equilibrium driving those other nutrient flows in the ocean and may stop critical nutrients flows into areas that rely on them. Any major local change to nutrient balance changes the equilibrium and thermodynamic gradients of the entire system.

In hindsight this is kind of obvious. There are similar equilibrium problems in large chemical reactors too and the ocean is just a giant reactor vessel to a first approximation. I think the original assumption was that the ocean is so big that no one would notice but long distance effects on local nutrient balances were observed such that increased sequestration productivity in one area was at least partially offset by losses of productivity in other areas due to new nutrient bottlenecks.

In principle modeling the entire system would allow one to inject the right nutrients at the right handful of spots to maximize aggregate sequestration performance with minimal risk. Building such models is still very much beyond us.

Sorry about a naive question. If additional nutrients causes imbalance due to taking nutrients from other areas. Cant we add those nutrients in as well?

I am starting to think China will be the first to experiment with this in large enough scale.

theoretically yes, but this draws you away from the original objective of effective sequestration

Wouldn't this only be an effect that happens on a small scale? It means that you'll see large changes elsewhere from small blooms in the ocean because of depletion elsewhere. Ok. But that cannot occur if you do this to an entire ecosystem (which can be the ocean, sure, but perhaps doing it to a large lake first would make more sense.

Second aren't we already doing large scale iron fertilization of the oceans? Not "intentionally" but simply rivers with human economic or residential activity along them.

  aren't we already doing large scale iron fertilization of the oceans

Usually the opposite actually. Dams impede a massive amount of sediment from flowing into the oceans. Most large rivers near humans have multiple dams at this point.

It's kind of too obvious to notice, but the ocean is largely contiguous and interconnected. Any "local" effect can be distributed clear across the planet by ocean currents in a matter of days.

How does consumption of a nutrient stop its production?

It's not stopping the production, but changing the flow.

suppose there's a flow of nutrients of type A from area one to area two. Currently, iron is the chokepoint in nutrient consumption of A, so that A is never completely consumed while going from one to two.

By adding excess iron into area one, or in the middle of the region between this flow from area one to two, you now have the possibility to consume A completely as iron no longer limits A's consumption.

So what happens to area two's consumption of A, if it became more scarce? May be nothing - or may be you now have another choke point of resources that wasn't there previously, leading to a change. If you weren't sure if this change would occur, or dont know, perhaps adding iron to area one is not a good idea, until such outcomes have been studied and acertained first.

I only use my common sense here, but it doesn't stop the production it just prevents the transport from the source to the destination through the area that was previously iron deficient and couldn't use the fully the other nutrient which passed on to another area.

In iron sulfate fertilization you're only adding two nutrients (iron and sulfur). Now that nutrient is in excess in one area so metabolic uptake of all nutrients increases locally, creating a concentration gradient that reduces nutrients available elsewhere. This leads to one of the other limiting nutrients like phosphorus or nitrogen preventing growth of other life forms in another location since the concentration gradient created by the phytoplankton sucked it away. Also sulfur concentration changes metabolic pathways through epigenetic effects so there are other effects just within the phytoplankton that depend on the species that happens to be present that will determine what the exact concentration gradient would look like. The dynamic of nutrients shifting of the metabolome makes modeling and risk assessment difficult since some species are known to produce toxins which can bioaccumulate. https://en.wikipedia.org/wiki/Phycotoxin

Not sure if it's a time to cry about the loss of a bush of roses when the forests are burning. Any natural iron supplementation like blowing the dust from Sahara or a river carrying out to the ocean waters full of red soil should be causing similar effects. Granted, rivers are likely carry other nutrients, often in excess, but this also does disrupt what grows or not in the surrounding areas.

Iron fertilization may still be pointless since the effectiveness is being debated afaik. On the other hand if it does work well for a competitive price compared to other methods, I would rather have a fish in the middle of the ocean full of algal neurotoxins and lower global temperature than the same fish cooked. No need to at it though.

Adding sulfur as a nutrient to the ocean is unlikely to have much effect, as seawater already contains about 3 ppm sulfate, thousands of times the concentration of iron.

It causes hypoxic zones in the water near the blooms, because the excessive blooms take up all the oxygen in the water leading to hypoxic and deadly conditions afterwards. That's why you often see so many dead fish around excessive blooms, all the oxygen is used up.

Totally agree: it's filed under "promising but risky" for a reason

@grok what are some papers supporting this rather negative take and are there other papers that refute the skepticism?

I'd love to see some small scale experiments in geoengineering. Despite multiple climate agreements, over my life time - I have not seen any actual progress on climate change outside of technological advancement. Technology such as wind, solar, BEVs, and similar appear to be coming far too slowly to avoid catastrophe. Perhaps China's recent push on BEV and similar technologies will tip the scale, but I am skeptical.

Human's have been geoengineering for millenia via clear cutting of forests, bio engineering of crops, fertilization of fields, damming of rivers, and other activities. While there will certainly be consequences and side effects, even a partial sequestering of ~20B tonnes of CO2 per year would meet the Kyoto protocol.

Are the consequences of Geo Engineering so disastrous that we should accept the worst case scenarios of global warming.

Doomberg has this theory that worldwide consumption of a source of energy never decreases, any fossil fuels extracted will be burned somewhere, and green regulations or subsidies just shift around who does the burning. Adding new sources of energy to the mix only reduces the rate of growth in fossil fuel consumption, but it still goes up.

Oil consumption didn't reduce coal consumption, it just added a new energy type. Same for natural gas.

So far they've been right. Decreased coal usage in developed countries has been offset by increased coal usage, of the now cheaper coal, in developing countries. German electric consumers are effectively subsidizing Chinese and Indian consumers.

Eventually that will turn around, if only because we start running out of fossil fuels, and the thesis will fall apart. But it will take far longer than we have, and we have far more fossil fuels than we can afford to extract and burn. That means the ONLY way to address climate change, which is a global problem, is through technological innovation. Regulation is a dead end, and just looking at the track record of regulation so far, it's hard to deny that.

That means making green alternatives that are better, and we're making some good progress on that. Electric cars are better in most ways for most uses except price. Solve that last one and they'll quickly displace combustion vehicles for most uses. Range is already good enough most of the time for most of the people.

It may also mean doing some geoengineering to soften the impact of global warming that will continue for multiple centuries if we don't intervene.

I think you're drawing the wrong conclusion from this set of facts and claims.

What I think you're saying is:

1. The only solution to this problem is technology that gives us alternatives to fossil fuels.

2. However, even if this technology becomes ubiquitous and cheap, it won't solve the problem by itself. Absent some forcing function, people will continue to use fossil fuels as long as they're convenient and available.

All of which may be true. But then you make the weird third claim:

3. Regulation is a dead end, and just looking at the track record of regulation so far, it's hard to deny that.

It seems to me that the only possible implication you can draw from facts (1) and (2) is that we are going to need massive amounts of regulation to discourage fossil fuel usage, since it won't drop organically even when sustainable alternatives are cheap and available.

PS As a totally unrelated note, here's a chart of global whaling activity. https://ourworldindata.org/whaling

When a big systemic circle is imbalanced, we often feel that adding a smaller circle of push or nudge will balance it.

But there are wobbly second order effects and the curves finally settle in the third order, often further away from our initial imagination.

Iatrogenics is the branch of science studying outcomes where interventions make the situation worse off.

Not a judgement on this or any other method, but a recurring pattern to be aware of.

…yet, it is also an excuse for not trying to address problems with technology. “The precautionary principle” has paralyzed Europe, for instance.

> “The precautionary principle” has paralyzed Europe, for instance.

A lot of modernity problems would be solved if those in power learned to sit on their hands and do nothing.

Paralyzed Europe in what respect?

The other way to promote plankton growth is through mimicking whale excreta. The https://www.whalexfoundation.org/ is engaged in this. We have far fewer whales in the ocean that we had hundreds of years ago. Ocean plankton, specifically phytoplankton, accounts for approximately 40% of the total global carbon captured and stored.

The hard part is actually measuring how much carbon you can sequester per kg of 'fake' whale poop.

Recent Bloomberg video: https://youtu.be/ZnXHJD0UI5U?t=812

(Disclosure - I am peripherally involved.)

So it was actually pirates all this time:

https://commons.m.wikimedia.org/wiki/File:Pirate_Global_Warm...

Being a get-rich-quick alternative to whaling, piracy captured enough of the workforce to slow down the extinction of whales.

I jest, of course, but it's fun to look for ways a mere correlation might be a causal relationship.

Instead of mimicking whale excretes we could ... let real whales excrete. that is doing everything to preserve remaining whale populations and encourage the formation of new populations.

Definitely, I'd love for there to be more whales!

Can't be more whales if the oceans boil before they can repopulate

We can do more then one thing at a time.

Evidence suggests we can't really even do one thing at a time.

Hehe.. to get more whales in the oceans, not doing something is a good start.

>The hard part is actually measuring how much carbon you can sequester per kg of 'fake' whale poop.

Do we have a rough estimate of this number? I assume the cost of whale poop can be low once it is mass manufactured. But the real cost is the actual deployment?

We do, we have a model and some experimental data. I can get back later for you with some numbers.

Later .. 200 litres of 'aqua food' for one tonne of sequestered carbon.

How long does it take to capture that one tonne of carbon?

Our Annual CO2 emission is about 40B tons. In order to be Carbon Negative we need to capture 60 - 80B tons / year.

That is about 80B x 200 Litres of Aqua Food. Or 16 Trillion Litres. Roughly 3 to 4 times the amount of soft drinks Coca cola sold per year.

And doing it continuously for 20 years we would revert back to about 80s.

No form of carbon capture can offset our current emissions. Also, it's incredibly stupid to use capture for that anyway, as it's always much cheaper to cut the emissions at the source.

Carbon capture is for offsetting historical emissions, and the few niche ones that are so hard to replace that we'll need decades of research.

We can't do it all this way. For every ton of carbon absorbed you add some multiple of that in plankton biomass.

I'm no ocean ecologist, but it seems like there might be several consequences to adding billions of tons of plankton to the ocean

It dies and sinks to the bottom of the ocean.

How far is our technology from being able to develop species of fish, that would bring up dirt from ocean floor, doing fertilization by themselves?

It's almost certainly impossible to create a species of fish that can take things from the ocean floor all the way to the surface for any significant percentage of the ocean. And we are certainly nowhere near having the ability to bionegineer such complex behaviors, we're far enough that you wouldn't even have a reasonable estimate for how long it might take to get there.

Why is it impossible? it can be as simple as a bottom feeder species that goes to the surface to poop, basically like whales, or have cells in their gut that produce fiber making their poop float to surface, or a combination of seaweed that produces floating wood, and a fish that builds nests on it. The second version is probably in reach of current technology.

Look up the blobfish and how it more or less explodes when taken from the deep ocean.

Very, very few animals can handle the pressure differential between the top and bottom of the ocean. It's pretty much just whales, and they can only do it because they're so goddamn big

the average depth of the ocean floor is something like two and a half miles and the pressure at that depth is 400 atmospheres.

You're actually describing whales

Kind of, but i mean if it was a smaller and more numerous species, it could have larger impact.

From what Recall, this is currently illegal under international law about dumping things into the ocean.

Given the parallels to antimicrobial resistance—and now agricultural overlap via azole fungicides—it feels like we’re sleepwalking into a serious global health issue. Curious if anyone here has experience in pharma, biotech, or policy who can shed light on what's structurally blocking progress.

I don't mean to be too flippant, but the way climate change is going, the Australian bushfires mentioned in the article will be a regular occurrence. I'm pretty sure I wouldn't want to know where the tipping point for "enough" to contain our current carbon emissions is. At least there is some upside to it..

I'd like to see them give it another shot off the coast of the usa/canada just like last time. To see if the pink salmon population absolutely explodes like last time they did it.

It might, the question becomes "At what cost to other areas?"

But it feels like we're tinkering with a system we barely understand. Ocean ecosystems are delicate, and messing with nutrient flows or phytoplankton populations could have weird downstream effects (literally and figuratively).

You're not wrong, but I think people also underestimate how out of balance the system already is.

It's not like Earth is this perfectly spinning top that some people want to give a nudge. It's more like it's already crashing about while we keep whacking it harder and harder with billions more barrels of oil injected into the atmosphere every year.

I agree we shouldn't recklessly throw new shit at it, but incremental experiments might be worthwhile.

But humans have already been tinkering (tinkering is not the word to describe large scale disturbances) with delicate systems we barely understand since the industrial revolution. But when it comes to technological solutions like this, somehow people think that's too risky.

We're already tinkering by dumping shitloads of carbon into the atmosphere.

Darkening the water of the whole planet so that it absorbs more sunlight and reducing albedo sounds counterproductive.

Wouldn't the darkening be temporary? After the bloom, the plankton are either consumed by ocean life, or die off and sink to the bottom (sequestering carbon in either case)

Taking geoengineering seriously is a sign of truly taking climate change seriously.

Like the alcoholic not changing their ways, in the back of the mind counting on that kidney/liver transplant to save them

So is nuclear energy but not much happening there. Also renewables of course.

The cost of nuclear is not an inherent feature, it is a conscious choice. Choosing to make nuclear expensive, especially while allowing other, dirtier, less reliable power generation methods remain cheap, is a sign of not taking climate change seriously.

Yes, yes, I know. It's always someone else's fault. Nuclear can never fail, it can only be failed by those unworthy of its glory.

Yes, but as long as you keep research so it may become cheap in the future.

It has lots of niches where it's actually cheaper anyway. It just can't be the dominant form of energy generation.

I’ve always loved this idea but I’m scared of what unforeseen monkey’s paw issues might arise.

Valid concern, but it seems like the glide path—continued carbon dioxide buildup and climate change—might eventually be worse than the unknown unknowns. (I suppose how one makes that decision is the challenge, hence the need for further study, per the article.)

This is one of the few carbon capture approaches that appears to be able to approach global scale, so I'm rooting for it. Even enhanced weathering suffers from needing to move billions of tons of rock, but scattering trace minerals seems pretty high leverage. The sheer mass of material that must be removed from the atmosphere is otherwise very intimidating.

I think everybody who has thought much about it has similar concerns. I'd propose we start soon, start small, ramp up slowly, and be thorough about the data collection.

As uncomfortable as it is to experiment on the only planet you have, even worse would be to wait too long and then, in a panic, try to do everything that might possibly work all at once and to as extreme a degree as possible.

Once there will be a business around this and people will make money the businesses will maintain a lobby to keep doing it and even increase the operation.

Iron enrichment of the ocean seems to have fallen in popularity compared to atmospheric aerosolizing, but the iron enrichment seems less risky to me. I agree that it seems better to start now, start small, and collect as much data as possible to understand all the subtle dynamics in play. That seems better than holding off for twenty years and then going big in a desperate hurry.

Totally get that. It's got that classic "elegant in theory, terrifying in practice" energy

I find the attitude of "it's more important to not be blamed if something goes wrong than it is to solve the problem" to be incredibly annoying. It's like the epitome of bureaucracy.

This, and stratospheric aerosol injection are both:

1. Incredibly cost effective 2. Mimic natural effects 3. Could pretyy easily cause anotger ice age if miscalculated

I wonder at what point the potential benefits will outweigh the potential risks for using these geoengineering techniques. Cant be far off, right?

Sulfur dioxide injection could halt global warming in its tracks for a measly $18 billion a year. I wonder if a vigilante billionaire climate activist gonna take a try in the next few decades..

> 3. Could pretyy easily cause anotger ice age if miscalculated

Could they? At least for stratospheric aerosol injection it would be easy to just stop doing it if things seemed like they were tipping. It doesn't happen _that_ fast, we'd have time to notice and react.

It depends on how badly we may miscalculate the aerosol deterioration rate. If we inject a bit too much and it stubbornly stays airborne, that would be a hard geoengineering problem to tackle!

I'd say that things are not bad enough for anyone with the means to take the risk. When the things get bad enough for the Overton window to admit geoengineering, it may be too late for simple and affordable solutions, as usual.

We have some experimental data on this, though, since jetliners and volcanoes both inject sulfur into the stratosphere. The global air traffic halt of 2001 and the aftereffects of eruptions have been heavily studied.

(It would be ironic if the world's response to fossil CO2 emission is to mandate extra high sulfur jet fuel, but nothing would surprise me)

Another example is the https://en.wikipedia.org/wiki/Year_Without_a_Summer caused by the 1815 eruption of Mount Tambora

I wonder whether you have studied what happened in the past several centuries after major volcanic eruptions.

Imagine a nation state started doing this. Lets imagine the Netherlands because they realise that it is worth it for them alone when so much of their land is at sea level. They hope to reduce worldwide temps by 1.75C (to pre industrial levels) within a year or so, which would immediately halt sea level rise.

I think other nations will demand they stop - with threats of sanctions - simply because there are other nations who now depend on the higher temperatures and increased agricultural output.

Conversely, imagine a nation state like India that will experience mass death events if heat/humidity waves become too much worse. They would continue geoengineering even in the face of threat of nuclear retaliation because the consequences would be so dire.

I have thought about this a lot from the perspective of cheapness, and think that simply having giant teathered robot crawlers pump ocean sediment back up into the top layers of the water collum and inject any missing nutrients into the naturaly found mix. Off shore areas that are shallow enough for wind, oil and other development, could then provide the nessesary power and servicing platforms. so , some sort of power source, undersea electrical cables to each unit, a hose that goes up to a submerged unit that has the discharge, and if needed holds additional elements for dispersal, possibly having a surface floating element will make more sense, or having tanks that sink down to the bottom crawler, and when empty are filled eith air to float them for recovery.

Don’t build another boat to do it, grant ships that install iron distributors a tax credit

I wonder if there's anything that could be added to marine bunker diesel fuel that would do this without screwing up the engine?

western companies won't do it unless money is gained from it. Nothing god related keeping them from taking action, just the lack of money related incentives.

Confirmed. Simple naked greed . Where is the money in that? A few quid for the coffers?

Maybe don’t do this.