Can we really prevent all warming for less than 10B$ with the mostly side-effect free geoengineering technique of Marine Cloud Brightening?

Next steps are connecting an interested funder, the most competent researcher in the area, and someone who has some relevant engineering knowledge to figure out which experiments would maximize further information to tackle the biggest uncertainties in the model. Mainstream philanthropy will only take interest once someone does the weird thinking and logistics for them.

I would guess ~zero chance of any public funding for this. Professional hand wringers aren't incentivized to solve problems. If before any charities had already scaled it you had approached people and told them you thought distributing insecticide sprayed bed netting might be the most important thing in global welfare you would have gotten a mix of polite interest and scoffing that never would have gone anywhere.

Edit: looks like I'm wrong. The project is housed at a public university which presumably means it has received some grants. I'd still expect a motivated team to outperform the entire org. Looks like they produce <1 paper per year on average. All the collaborators probably have other things that are their main projects.

It's worth noting that projected costs are as high as 1 billion per year per W/m^2 of reduced forcing. Still trivial in the grand scheme of things, but quite a bit different than expected total cost of 10B.

(Even if cloud brightening is the ultimate solution to warming, we still need to address ocean acidification and carbon sequestration, and I'm not aware of any ideal solution to those problems yet, but two weeks ago I wasn't aware of cloud brightening, so for all I know the problem isn't a lack of investment, might just be a lack of policy discussion.)

There is also http://projectvesta.org which claims that it is possible to remove CO2 from the ocean and atmosphere via olivine weathering reasonably cheaply.

I have a few technical quibbles here.

1. It's not quite accurate to imply Philosophical Transactions of the Royal Society B itself has made a claim about the robustness of MCB. Generally only an editorial endorsed by the editorial board should be taken as a statement about the journal's position in particular. Generally academic journals provide a forum for academic debate. Only the authors of an article are really standing behind the position. The journal only publishes work of a certain standard, and publishing a paper is somewhat an endorsement of the quality of work in the paper, but not of the finding itself.

2. Generally I understand it is not a given that MCB will work. Only the sulphur dioxide solution is really proven, and "sulphur" makes me nervous (I don't know if there are good grounds for that). More research is needed on MCB, which a point in favour that the research should be funded and carried out as soon as possible.

3. It may be that researchers could do research into MCB without it being seen as an endorsement by the entire field that we don't need other solutions. MCB can and should be presented as important experimental work that needs to be done, as a last resort. When it is actually proven, I think that's when we have the dilemma about what to tell the public. But at that point, looking at the status quo, it may be our only option left.

The 2015 report "Climate Intervention: Reflecting Sunlight to Cool Earth" says existing instruments aren't precise enough to measure albedo change from such a project, and measuring its climate impact is even more tricky. That also makes small-scale experimentation difficult. Basically you'd have to go to 100% and then hope that it worked. As someone who ran many A/B tests, that makes me hesitant to press the button until we have better ways to measure the impact.

we still need to address ocean acidification

And changes in precipitation patterns (I've seen evidence that reducing solar incidence is going to reduce ocean evaporation, independent of temperature).

There's also the "double catastrophe" problem to worry about. Even if the median expected outcome of a geoengineering process is decent, the downside variance becomes much worse.

I still suspect MCB is our least bad near- to medium-term option, and even in the long term the possibility of targeted geoengineering to improve local climates is awfully tempting, but it's not a panacea.

As an unrelated aside, that CCC link rates "Methane Reduction Portfolio" as "Poor"; I'd have marked it "Counterproductive" for the moment. The biggest long-term global warming problem is CO2 (thanks to the short half-life of methane), and the biggest obstacle to CO2 emissions reduction is voters who think global warming is oversold. Let the problem get bigger until it can't be ignored, and then pick the single-use-only low hanging fruit.

I do buy the claim that public support for any sort of emission control will evaporate the moment geoengineering is realised as a tolerable alternative. Once the public believe, there will never be a quorum of voters willing to sacrifice anything of their own to reduce emissions.

I wonder if the possibility of geoengineering has already significantly reduced support for emission control, since the idea has been written about in popular science media for a while and isn't exactly a state secret. Also, if we don't put more effort into studying the actual cost and feasibility of geoengineering, it will be really disastrous if the cost turns out to be much higher than current expectations, or the idea turns out to be infeasible (without causing other serious side effects).

"With Solar Radiation Management techniques specifically, it is not possible to be certain of the effects on ecosystems’ biodiversity, since it will create an entirely new ecological balance (or disturbance) (Alan Robock., 2016). The energy from incoming sunlight is an essential resource for life on the planet and is closely linked, for example, to supporting the oceanic algae that produce most of the world’s oxygen"
From the book "The Big Bad Fix", 2018

In our discussion and potential actions, we should not focus only on climate-related side-effects. We should take into account risks connected to the ocean ecosystem functioning. The ocean is full of living organisms that depend on each other's functioning, and some of which depend on light. Because of this interdependence, a whole ecosystem can collapse if a certain species would be eliminated (this called "tipping point" in biodiversity discussion). The conditions for such a collapse for ocean ecosystems are yet poorly understood. But this remains a risk of successful or unsuccessful deployment of any of Solar Radiation Management techniques.

Edit: I ended up spending a bit over a day looking into geoengineering and the Copenhagen Consensus Center after writing this, so go look at my answer for a more informed take that includes what I learned from doing that. My below 2 long-form comments are not exactly wrong, but more poorly informed than that answer.

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Awesome! I'd wanted to know what the actually useful geoengineering stuff was.

I do buy the claim that public support for any sort of emission control will evaporate the moment geoengineering is realised as a tolerable alternative... Major emitters have already signalled a clear lack of any real will to change. The humans will not repent. Move on. Stop waiting for humanity to be punished for its sin, act, do something that has some chance of solving the problem.

From a game theory POV, "dont pressure emitters" is basically just "surrender". In theory, "emitters who don't want to change" can and should be coerced by force, whether that's within a nation by laws (which will ultimately be enforced with force if broken), or internationally, by threat of military force that's willing to follow through. Like, that's how you'd game theoretically not lose.

In practice, fuck me if you're able to get any coordination to work.

There's a case for, "don't do geoengineering until you have an actual solid international power alliance capable of doing regulation". Because then the emissions agreements are set.

In practice, what's the actual utilitarian thing to do? Well, the main unanswered question is, how much can cloud brightening be scaled? Can it keep temperatures constant if emissions levels go 5, even 20x? Secondly, what can be done about e.g. ocean acidification and other non-warming issues? I have zero knowledge here. But if it scales that well, then throw out the game theory and just do the geoengineering.

If you're a lone EA and you're trying to use this information, presumably your options are, "do startup and try to get >$10B", and "gain control of a tiny country, boost military, start threatening emitters".

added: or "do startup, make money, then fund research".

Before this, the only other low-budget method of planetary cooling that I knew, was dumping sulfate aerosols in the upper atmosphere (from rocket or balloon), in imitation of volcanic eruptions and dirty coal burning. The tactics have two things in common. One is that their immediate effects are regional rather than global, the other is that their effects quickly get washed out unless you keep pumping.

Carbon dioxide disperses through the atmosphere in a relatively homogeneous way. But these much larger particles will remain concentrated at particular altitudes and latitudes. So certainly when and where they are released will need to be carefully chosen.

As for the short lifespan of the particles, again it contrasts with carbon dioxide. Once a carbon dioxide excess is created, it will sit there for decades, possibly centuries. There will be turnover due to the biological carbon cycle, but a net reduction, in the form of uptake by natural carbon sinks, is a very slow process.

The carbon dioxide sits there and traps heat, and the sulfate aerosols or water droplets only alleviate this by reflecting sunlight and thus reducing the amount of energy that gets trapped. So the moment you stop launching sulfate rockets or turn off your seawater vaporizers, the full greenhouse heat will swiftly return.

That's why extracting and sequestering atmospheric carbon is a much more permanent solution, but it is extremely energy-expensive, e.g. you can crack open certain minerals and CO2 will bond to the exposed surface, but it takes a lot of energy to mine, pulverize, and distribute enough of the resulting powder to make a difference. Some kind of nanotechnology could surely do it, but that would be a cusp-of-singularity technology anyway. So there's a reasonable chance that some of these low-cost mitigation methods will begin to be deployed, some time before singularity puts an end to the Anthropocene.

... public support for any sort of emission control will evaporate the moment geoengineering is realised as a tolerable alternative. Once the public believe, there will never be a quorum of voters willing to sacrifice anything of their own to reduce emissions

More precisely, public support for emission control that requires personal sacrifice. Energy efficiency measures have been estimated to cost “substantially less than the cost of meeting electricity needs with new power plants”, for example.