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Mine olivine rock, spread it on a small percentage of tropical marine beaches with high levels of tide energy, remove CO2 from the atmosphere.

What could possibly go wrong?

Edit: not sure why the downvotes. Perhaps I should have explained my skepticism more clearly? Any geo-engineering initiative almost always fails to predict the unintended consequences for the environment - e.g. perhaps one day we'll discover that too much olivine rock on beaches destroys ecosystems, or something else.

> What could possibly go wrong?

Nothing. It already happens in nature, but at a far smaller scale. It is not a self-renewing or runaway process. The point is to distribute the correct amount of olivine to stabilize CO2 at ~200 PPM which is close to its pre-industrial level.

> It already happens in nature

4000 ppm CO2 was found in nature far before pre-industry came along. Does the fact that anything "happened in nature" make it "ideal?" What is the globally "ideal" level of CO2 anyway? Certainly 200ppm is an order of magnitude low when considering the ideal for plants.

4,000 ppm was a period far before humans or advanced primates, and very different flora.

200ppm is around the level humanity, and much of the flora we share the planet with, evolved. It's the level we started to develop from, to farm.

Nature and the planet has no ideal, it copes with whatever there is. Humanity on the other hand would appear best served by the level we evolved with - 200ppm or thereabouts. 400ppm causes problems for us, 4,000ppm would almost certainly be the end of us or as near as makes no odds.

Greenhouse owners generally spike their air to 1200-1500ppm CO2. That's the compromise between best cost and best for the plants and is lower than these species evolved in.

As to humans, 400ppm causes zero problems, matter of fact, OSHA says 1000ppm for continuous exposure. NIOSH says 10,000 ppm for a 10 hour work shift.

For instance: https://inspectapedia.com/hazmat/Carbon%20_Dioxide_Exposure_...

The GP obviously doesn't mean that 1000+ ppm CO2 is toxic, they mean that the changes to the environment it would cause are less than ideal for humans to thrive.
>As to humans, 400ppm causes zero problems

You mean it causes zero known problems.

Medicine and biology are not yet advanced enough to say in most case whether putting the human body in a condition humans haven't experienced in 800,000 years is harmful. It took decades to learn that asbestos is harmful. If the harm caused by asbestos were cognitive decline rather than shortened lifespan, it probably would've taken longer, and cognitive decline is the effect that appears at the lowest concentration of all of the known adverse effects of co2. (One study found cognitive decline after 2.5 hours of exposure to 1000 ppm.)

Plants use co2 to make their bodies just as we use proteins, fats and carbohydrates to make our bodies, so I am not particularly reassured by knowing the plants thrive at very high co2 levels.

Graph of co2 levels over the last 800,000 years: http://kaltesonne.de/wp-content/uploads/2017/03/co2-1024x576...

Humans in isolation can tolerate 400ppm. Offices and houses accumulate far more than outside it pushes to far higher inside, enough to breach health and safety recommendations, cause decreased performance and so on. We don't know where planetary equilibrium would settle at 400ppm as we're still emitting. Looking outside and no longer in isolation >400 seems to be causing some pretty wild changes.

I'd say that's far from zero problems.

>4,000ppm would almost certainly be the end of us or as near as makes no odds.

If by "end of us" you mean human extinction, I'm curious why you think that. Reducing the co2 in a building to whatever level one wants is cheap enough (by bubbling air through water mixed with soda lime or lime) that it seems to me feasible for a few million humans to survive indefinitely even without major advances in technology. (I am assuming that the cost of a co2 measuring device, currently over $1000, could be driven way down before they would be needed in large numbers as part of the machinery to reduce co2 levels inside buildings.)

Wouldn't most food crops would grow much better at 4000 ppm than they do now?

People would be able to go out into the 4000-ppm-co2 outdoors for hours at a time with no obvious serious problems. (I exposed myself to higher levels than that for years by sleeping in a very small room with very low "draftiness". Not recommended of course.)

Co2 at 4000 ppm would kill billions of us and make the survivors miserable and is certainly something I wish for humankind to avoid, but that is different from human extinction.

So you can breathe easily if you can afford bubbler supplies, hmm. Not sure the global economy is surviving 4k ppm unscathed though. Not entirely convinced "the economy" will mean anything at all any more. :)

End of our civilisation. End of us as an industrial society. Perhaps as relevant and historic as the Romans or Ancient Egyptians. I'd prefer to stop long, long before that.

Who knows all the knock on effects of 4,000ppm, I certainly don't except to say it's way beyond the worse case models I've seen. End of much productive work outside. Reduced performance for all. Probably much of the equatorial and tropical simply uninhabitable. We'd be looking at what, 7, 10, 12 degrees? I have no idea. Heaven knows how many reinforcing tipping points will kick in. I don't think we can confidently say it won't result in actual extinction. Even if it probably won't.

We'd lose both ice caps, so something like 60 odd metres of sea level. How many major cities and entire countries does that lose? I've seen maps that at just 4C much of the USA's farm land would be near desert, and the Sahara greening. Unprecedented temperature, habitat and rainfall changes with no idea which species will make it, and which not, maybe many we depend on to eat. How much forced and unwelcome migration? Which prediction is the accurate one? With that energy in the system are we looking at cat 10 super-hurricanes?

Does it matter if it's 0%, 1 or 2%, or even 10% are grubbing out a post-apocalypse zero growth life or whether it's Mad Max, 18th C or bronze age? Unrecognisable. Unpredictable. Survivors would tell fables that their ancestors did it. Knowingly. Maybe some other species gets its chance and does a less idiotic job.

I don't think the difference matters. At all.

You hear that everyone? "QuickToBan" on ycombinator has officially put his stamp of approval that literally NOTHING can go wrong attempting a geo-engineering process of this magnitude! What a relief!
> What could possibly go wrong?

As the water level rises we're gonna need to lose some of the cynicism around geo-engineering.

Unless you're convinced that society will somehow value the stability of our climate over economics? I feel like there's more evidence (given our snail-like progress over the past few decades) to demonstrate that's a not gonna work out compared to attempting _some_ form of geo-engineering.

I'm all for Geo-engineering if it is done in the right way to further benefit all of society and the planet. Sadly as humans we have never all come together for the benefit of the planet yet, and I am doubtful we will in the near future.

My fear is that once people figure out how to Geo-engineer things with fine tuned results that it will eventually be used as a weapon.

Imagine if you could turn up the temperature of an area to create a drought?

Or flood/freeze out an area?

This could be done covertly as it would be hard to identify the exact cause if done under the 'radar'.

No bomb shells or traces left behind to place blame.

I'll pass on homo-sapiens ego presuming they are smarter than the planet and can fix any problem using technology and our brains.

Maybe for the first time in History we may be smart enough to mitigate the potential ill effects of the climate cycle, however this planet was here long before humans and will probably be here long after.

There was a joke once, about human's being the planets Herpes, which seems to be a good metaphor for our existence on this rock.

Technically you cannot use weather modification as a weapon but when has the rule of law stopped crazy people.

https://en.wikipedia.org/wiki/Environmental_Modification_Con...

To restate I am all for being able to help the planet, mitigate our impact using new greener technologies and changing our habits, however this needed to be done a long time ago and trying to fix our current problems with the band-aide of Geo-engineering I personally believe is a futile effort.

I think we as industry and society know nothing about geo-engineering, am I wrong? if yes doesn't this create big changes of failing and create more damage? If no can we point on geo-engineering to substain what we are doing wrong in terms of waste production and environment destruction?
Even if it has unintended, negative consequences... would they be worse than say the consequences of pulling the clathrate gun trigger?
I'm sceptical. Are there calculations on shipping for the olivine? If it's primarily mined in certain parts of the world it's going to have a big cost in shipping - there's a reason why regular sand is sourced as locally as possible. It weighs a lot, which means that it's expensive for both the wallet and the environment to ship.
From Their Site:

What is the Life Cycle Analysis Costs of CO2 Incurred in the Mining, Milling and Transport? The Life Cycle Analysis (LCA) of the release of CO2 from mining, milling, and transport of olivine creates an approximately 4-6% loss on CO2 removed. We will always work to minimize the transport distance from the source of olivine, and utilize low impact transit such as rail and boats. Further, many tons of olivine are already mined because the deposits are found above other valuable minerals, such as diamonds (found in a rock formation called Kimberlite). Utilizing these piles of waste rock, known in the industry as tailings piles, will allow us to harvest olivine without causing a significant CO2 output. Further, the dust from mining itself can contribute to the offset of the entire mine, as well as the very ground where the olivine is exposed. It starts weathering right away, and many ultramafic mineral mines, abandoned or active, eventually offset their own footprint and even go towards negative emissions. On of our olivine weathering rate sources is actually these tailings piles. See these studies:

Carbon Dioxide Fixation within Mine Wastes of Ultramafic-Hosted Ore Deposits: Examples from the Clinton Creek and Cassiar Chrysotile Deposits, Canada

Integrated Mineral Carbonation of Ultramafic Mine Deposits—A Review

LATERITIC EVOLUTION OF THE JACUPIRANGA ALKALlNE COMPLEX

Koornneef JM, Nieuwlaar E (in prep.) Environmental life cycle assessment of CO 2 sequestration through enhanced weathering of olivine. Working paper, Group Science, Technology and Society, Utrecht University

Hi, co-founder of Project Vesta here. Based on a CO2 life cycle assessment, to minimize CO2 created during transport, the idea is to utilize mines within 300 km (186 mi) of the destination beach. Including mining, milling, and transport, we can hopefully maintain only a 4% efficiency loss in terms of CO2.[1]

This paper has a few examples of models where it is 93% efficient for mines within 1,000 km. [2]

Fortunately, there are olivine reserves found all over the planet in a formation called dunite (contains 90% forsterite olivine).

Further, for many of the first beaches, we will be looking to use tailings piles (waste rock) from previously dug and developed mines, as well as the infrastructure from those mines, such as rail for transport. Since olivine is found in volcanic rock formations close to the surface, in the process of mining other minerals that are found in volcanic formations such as diamonds, many tons of olivine rock have already been dug up and deposited in large piles on the surface. By utilizing this rock we would not produce any additional CO2 from mining, and only from crushing/transport.

We are definitely taking the CO2 penalty into account in our calculations and strategy for deployment.

[1] https://projectvesta.org/science/#dflip-df_978/1/ [2] https://projectvesta.org/science/#dflip-df_93/2/

Hi Eric,

How do you plan to compensate countries who own the beaches or waters targeted by the project? Do you have an estimate of how receptive a community will be to having their beach turned green, especially if they rely on it for a portion of their income?

A country outside of the world's economic powers might want financial insurance in the event that the the project causes ecological damage and hurts their economy.

Several California cities are already spending millions annually to dump sand and rocks and to build/expand seawalls, to try to stave off the ocean taking prime beachfront real estate (and it's not working, in the long run).

Those cities (though not in the ideal location for this project, I guess) would likely be ecstatic to have subsidized assistance (though who subsidizes it?). They're losing the beaches no matter what they do, the question is how long will it take, what will it cost to push it out a few more years, etc. For cities that don't have the budget to dump millions of dollars worth of sand only to have it mostly wash away in the next storm, a green beach is probably much more appealing than no beach.

My main point was about developing countries. Eric himself noted that "the idea is to utilize mines within 300 km (186 mi) of the destination beach" and "or many of the first beaches, we will be looking to use tailings piles (waste rock) from previously dug and developed mines, as well as the infrastructure from those mines, such as rail for transport". The idea is summarized in this image [1], which shows mines and their associates beaches that the project intends to target due the proximity.

Most of those beaches are in developing countries. If nourishing the beaches with olivine has some unforeseen, negative ecological consequence, those countries might not be financially equipped to deal with the cleanup. How are those beaches going to be insured?

In the case of California, I'm not familiar with their beach nourishing process, but I assume they are using sand that is more similar in content to what was naturally present. If the beaches have been replenished for years, then we at least have some idea about the short-term effects.

1. https://projectvesta.org/wp-content/uploads/2019/04/Image-59...

Shouldn't the thing pay for itself in climate impact costs avoided?
The benefits are global though, while the impacts on beaches are local.
Which is true of all of the costs of climate change. The costs are already being most harshly felt in poorer communities and nations, and that divide will accelerate the more expensive and resource-intensive it becomes to keep living "normally" under climate change. As droughts strike rich regions, they'll build dams to retain water than would have traveled to poorer regions (e.g. as a significant portion of Californians want to do already at even the first hint of climate change striking the area, despite its impact on people to the south).

I don't know what the right answer is on this question, but I know that the pain of climate change will be felt by poor nations more than it will be felt by rich ones, no matter what. It may be that staving off climate change, even if it has its own negatives, is less bad than the alternative of doing nothing for those places and communities. But, maybe not. Hopefully it would get a lot of study and small scale experimentation before going big.

Will olivine-covered beaches be still good for recreation? Will olivine sand produce fine dust that would muddy the water?

I bet the first few green beaches would just look cool enough to increase he stream of tourists — as long as walking over an olivine beach feels safe and not unpleasant.

Also, is dumping olivine on rocky but flat enough shores an option? That is, may it not replace existing sandy beaches but form new olivine-only beaches?

Green Sands Beach on the island of Hawai'i is a big tourist attraction. So, yeah, it seems fine for recreation. (Except it won't be cool anymore if every tropical beach is green...)
They mention that only 5% of tropical beeches would need to become green.
Hi, yes the beaches would still be good for recreation and there should not be a noticeable muddying of the water. The existing beaches of olivine (such as Papakolea Beach in Hawaii that is pictured on our website) are safe and have no observed negative effects on wildlife or humans.

If you look at the tabletop shaker experiments on the website, the water is cloudy because it is not being refreshed. In an open-system such as on a beach with water constantly refreshing, that would not be an issue.

The olivine can be placed on any shoreline or coastal area. The "tropical shelf-sea beach" set up we constantly refer to is simply the optimal and preferential solution. The main effects we are utilizing the beach for are that (1) the tumbling motion of the waves causes a constant abrasion that breaks up a silica coating that rapidly forms on exposed olivine and (2) the collision of grains on the shoreline causes smaller slivers to chip off, that themselves rapidly weather.

We want shelf-seas because the grains will be pulled off the beach and will continue to be weathered through underwater shear stress forces on the sea bed. Other locations work as well, but the olivine may take longer to weather if there is less motion, colder water, etc.

Would the olivine actually need to be (rough) sand or would pebbles or, say, fist-sized rocks work almost as well?
How the beach feels mostly depends on the particle size; magnetite sand, quartz sand, and obsidian sand feel about the same. (At some extreme, that would presumably break down; I wouldn't want to walk on a beach made of shredded fiberglass, at least until it had gone through some physical weathering. And sawdust does feel different. But olivine is not such an extreme case.)
This seems like it would fail energetically; the amount of energy required to mine and transport a bunch of rock to a beach would surely exceed the amount of CO2 sequestered.
It seems like you didn't read the paper, or really anything on this.

But, to make it easy for you:

* 1 ton of Olivine will absorb 1.25 tons of CO2[1]

* Transportation cost is 161.8 grams of CO2 per ton mile[2]

* They are looking at mines within a 300km[1] (or ~190 miles) radius. That's a maximum transportation cost of ~31kg CO2. That's a rounding error.

* Mining cost for a ton of Olivine is ~$30/ton right now. Let's say it's all for hydrocarbon fuels, and they're cheap, so 30 gallons of fuel. Let's make it 50 gallons, because I'm lazy. A gallon of fuel produces 20 pounds of CO2[3], so 1000 pound of CO2. That's half a ton.

* Let's assume for reasons beyond our ken we'll spend another quarter ton of CO2 on this. Likely due to people arguing on the Internet.

That still leaves us with half a ton of CO2/ton of Olivine.

Maybe do at least back-of-napkin calculations before claiming things will certainly fail.

[1] https://projectvesta.org/ [2] http://business.edf.org/blog/2015/03/24/green-freight-math-h... [3] https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm

Mines or potential mining sites for extracting Olivine on this scale don't exist within short distances of these tropical beaches. Many of the beaches are on islands which are essentially coral heads above the water. Digging down to any deposits of other rock are going to require either significant effort in terms of dewatering, caissons, and equipment or else mining underwater.

This is a good idea that's probably not practical. It sounds ok if you accept that that much rock can be mined, processed, and moved within the constraints given, but they're probably not even close with these estimates.

On top of that, you're talking about completely changing the composition of the beaches in much of the tropics, displacing the existing beach materials and probably causing mass die-offs and disruption in the ecosystems attached to them.

Plus, you'll have to keep hauling sand. Beaches in active areas like the tropics aren't static. The sand migrates down them and out into the ocean. Sometimes islands like the Bahamas even have to dredge sand back out of the water to rebuild beaches.

Underwater sand isn't going to absorb much atmospheric CO2.

> Many of the beaches are on islands which are essentially coral heads above the water.

Afaik most Caribbean islands are of volcanic origin. Barbados is a notable exception, it's a coral island.

Actually, the caribbean is the area I'm most familiar with. Lots of small islands in the Bahamas chain with sand and coral beaches.

Perhaps islands in deeper water are volcanic, but I still doubt that mining that much olivine anywhere near the place it would be used is possible.

Actually I think underwater sand can absorb dissolved CO2 in water - that’s how it’s alkalising effect on oceans works. I think I remember Vesta’s docs saying there are places in the ocean (between the UK and Europe IIRC) with enough current flow that you could just put the Olivine directly on the sea-bed.
You're right, I didn't read enough or do enough back-of-the-napkin math. I read more; this seems plausible in life cycle terms, but now I have doubts about the economics. At $30/ton, 30Gtons becomes $900 billion a year. For comparison US discretionary spending is $1.4 trillion. It's not clear to me where this level of spending is going to come from (jewelry sales?), for an activity that has no useful economic output other than sequestering carbon. In addition I'm not sure that $30/ton is an accurate estimate of all of the capital outlays and so on required - entire industries have to be created to facilitate this process at scale. Much of this activity has to be done in decentralized fashion, i.e., it is not a single polity or entity that must partake in olivine mining to make this viable, which adds cost and political overhead.

I'm also not clear on what putting 30 gigatons of rock onto coastal sea shelves each year is going to do in terms of ecosystem impact, and how tolerant local polities will be of this. For example, Costa Rica gets something like 6% of its GDP from tourism, a lot of which is ecotourism; it seems unlikely they will be happy about a significant mining and rock-dumping operation taking over its beaches.

EDIT: Also, on the life cycle question, I'm unclear on how real the "1 ton for 1.25 tons of CO2" claim is - would a real beach weathering actually produce this much absorption per ton? Would it happen on a 1-year time scale so that we could actually offset this much every year? Uncertain; if you have citations demonstrating this please post them, if you're not above arguing on the Internet.

Olivine is mined at $25/ton right now, which presumably takes capital requirements into account, so that's less of a concern from my POV.

The need for $900 billion to make this work (or even $300bln if the olivine price really drops as they predict) is the hard part. But then, the alternative is pretty much climate collapse, so it's still a bargain. Question is if people will realize that soon enough. But yeah, definitely not paid through jewelry. I'd imagine an actual emissions tax with teeth might help.

As for ecosystem impact, let's for now just look at a per-country amount. CR is 5M people, ~1.6tons of CO2/yr, so 8 megatons. With 800 miles of coastline, that's a lot of rocks - if they were only deposited on the beach. But it can be dumped in the water as well, if the currents are right. See e.g. https://projectvesta.org/science/#dflip-df_90/26/ (Not CR, but Europe, and basically says "pour it in the Channel")

I don't have the weathering rate, and the claim in their booklet (p. 32) actually doesn't make sense to me, so that's the big question for me as well. AIUI, this is the big unknown - they claim the old numbers don't apply, but they need to run a large-scale test to actually tell what the numbers would be.

I'm not, to be clear, saying "don't be skeptical". I'm merely saying as far as CO2 absorption ideas at scale go, this is one of the saner ones. It's not immediately unfeasible, and we should probably test it.

(As you can tell, I'm a fan of arguing on the Internet ;)

"The Life Cycle Analysis (LCA) of the release of CO2 from mining, milling, and transport of olivine creates an approximately 4-6% loss on CO2 removed. We will always work to minimize the transport distance from the source of olivine, and utilize low impact transit such as rail and boats. Further, many tons of olivine are already mined because the deposits are found above other valuable minerals, such as diamonds (found in a rock formation called Kimberlite). Utilizing these piles of waste rock, known in the industry as tailings piles, will allow us to harvest olivine without causing a significant CO2 output. Further, the dust from mining itself can contribute to the offset of the entire mine, as well as the very ground where the olivine is exposed. It starts weathering right away, and many ultramafic mineral mines, abandoned or active, eventually offset their own footprint and even go towards negative emissions. On of our olivine weathering rate sources is actually these tailings piles."
At first I read this and was like "okay, you want to dump 30 Gigatons of Olivine per year for 'a number of years' on tropical beaches"

That sounds crazy, considering we pump out +10Gigatons of CO2 per year as it is. But, does the science actually make sense in that if we actually did that, we'd end up with less CO2 in the atmosphere, and subsequently the oceans? That would seem to make this a great tool (possibly among many) to clean up our mess once/if/when we stop putting so much CO2 out there in the first place.

Edit: I do wonder if this process would raise the alkalinity of the ocean too much in the other direction. I can't find the info on this on their site, there is so much to read!

At the moment the oceans are being acidified by dissolving more CO2 in them - I assume that if you dump enough olivine into them to negate that (or rather return them to preindustrialization ph) then long term you'll also soak up about the right amount of CO2
What I mean is, let's say this process is able to sequester sufficient CO2 in the form of bicarbonate to lower us to a conservative 300ppm CO2. At what point, if any, would we be turning the ph of the ocean to be too alkaline?
Well part of this process is supposed to precipitate out the carbon in forms that can eventually be subducted (as the current natural carbon cycle does).

I assume that the rate at which the carbon is sequestered by this method is also driven by the level of ocean acidity, as more CO2 is pulled out of the ocean the acidity will drop and so will the reaction rate will also drop ... this means that there's a natural negative feedback here - whether it's enough to "do the right thing" is probably still a question for science

This actually seems to have some promise - I'd be worried about other side effects (another article I was reading mentioned possible effects on marine life due to dissolved iron and nickel), but it seems like a technology that merits further exploration and rollout on at least a small scale.
I think I get the worry and skepticism about geo-engineering but to be completely frank we've been (inadvertently) geo-engineering the planet at least since the industrial revolution, so I don't really think we have much of a choice, especially since we need to go carbon negative, not just neutral.

This olivine solution doesn't really look any less viable than CO2 scrubbers, if I'm being honest.

I would rather we strengthen our forests than add more pollution. I guess if forestry is considered geo-engineering then I support it. But I don't think "we're already adding pollution, so we might as well add more pollution to try to net out carbon" is a sound argument.
Forests are helpful but not sufficient. The world was once covered in forests and all the oil/coal etc was in the ground.

Now we have reduced forest cover and burned underground carbon. Reforestation only solves the former.

We can harvest forests without reducing canopy coverage and store the wood. You can even grow your forests on top of wood landfills.
Reducing forest clearance and engaging in afforestation could be enough had anthropogenic CO2 emissions started dropping significantly in the 1990s. But they have continued to rise. Forestry changes aren't nearly enough to offset anthropogenic emissions from other sectors. They may be part of the solution but additional measures are needed.

Geoengineering is on the table now not because it is an easy shortcut, but because the world has failed to do enough in other ways. It's better for patients with prediabetes to change diet than develop full blown type 2 diabetes, but if diet doesn't change fast enough it's better to prescribe insulin than just let them die. Industrial civilization has discounted decades of warnings about changing its energy "diet" and will soon need more drastic measures.

I'm a little optimistic because renewable energy has become cheaper faster than I expected. I'm pessimistic because the world still isn't reducing fossil use fast enough (or at all, really -- so far the best news is "the percentage growth rate is slowing.") Even when the economics start to favor non-combustion energy sources, legacy fossil industries have often delayed the transition by obtaining government support to resist the economic pressures. So I believe that the world can transition to low-emissions energy but I also believe that it's not happening fast enough.

Even worse, the climate perturbation from anthropogenic emissions can trigger a dangerous positive feedback loop that will release even larger quantities of GHGs from natural stores as forests burn more frequently and permafrost thaws. I think that if people get the problem under control (as opposed to just suffering the effects, with no softening of the blow), it's going to involve 3 major prongs:

- Transition to non-fossil energy sources

- Geoengineering via solar radiation management, as a temporary bandaid to prevent runaway warming feedback

- Geoengineering via enhanced silicate weathering, as a thermodynamically stable fix for the excess CO2 added to the environment

Solar radiation management can be phased out as atmospheric CO2 levels drop. But with silicate weathering alone, I fear that thawing permafrost will outpace even the most ambitious CO2 drawdown efforts.

The second two prongs are still highly controversial and advocating for them tends to get one lumped in with climate denialists. I think that most people concerned about climate are going to come around eventually, though. The IPCC already has. We clearly aren't going to avert feedback loops by 2030 via emissions-reductions alone.

A lot of assertions there. You lost me at “Forestry changes aren't nearly enough to offset anthropogenic emissions from other sectors”. Can you explain your math there? Is there a limit to how much carbon we can warehouse in trees (living and milled)?
If you keep harvesting trees and store them in a way that they won't rot or burn, there is no practical limit on the total amount of carbon that can be sequestered that way. There is still a limit on the rate at which carbon can be sequestered that way. To stabilize concentrations of atmospheric CO2, the sequestration rate must match current rates of anthropogenic CO2 emissions. If significant feedbacks kick in, the sequestration rate needs to be higher than current anthropogenic emission rates.

Here's one of the more optimistic studies I have seen about forestry-based approaches to curbing CO2:

https://arstechnica.com/science/2017/10/co%e2%82%82-benefits...

The authors estimate that afforestation and other positive land use changes could provide up to 37% of the CO2 reductions needed through the year 2030 in order to stay under 2 degrees of warming. The other 63% has to come from elsewhere.

I'd agree with you if we could do what we need with just forests. But unfortunately we can't. Some other form of reducing carbon is a core part of any long term plan.

It's just bad enough now that forestry is no longer a valid option on its own.

Do you have data on the global capacity for intensive carbon storage forestry techniques? What are you basing that on?
We've been geoengineering the planet since at least the Great Oxygenation Event, for a sufficiently broad definition of "we".
For other mitigations to climate change, see Project Drawdown: https://www.drawdown.org/
It doesn't look like olivine is mentioned in that. Is it under some other name / concept?
This process is typically referred to in the scientific literature as "enhanced" weathering but we think that "accelerated" weathering is easier for lay people to understand.

Drawdown is mostly focused on things we can change in our current activity to lower emissions and less about methods for Carbon Dioxide Removal (CDR). Their top solution for becoming carbon neutral is "Refrigerant Management"...

I like the concept of the project and know some people working in the org, but in my opinion, they do not give enhanced/accelerated weathering enough credit as a potential solution, even though it can scale all the way up to global CO2 level emission removal. Many of the other solutions they suggest are limited in potential, yet featured prominently... I am working to communicate this to them.

https://www.drawdown.org/solutions/coming-attractions/enhanc...

https://www.drawdown.org/solutions-summary-by-rank

I didn't see the cost breakdown [1] mention how much they expect to pay countries for dumping olivine in their beaches/waters. Would a country, especially those near the equator, willingly agree to take part in an experiment like this for free? The referenced papers have explained how the project is safe, but I don't think communities or their representatives will see it that way.

1. https://projectvesta.org/#phaseIV

Many tropical countries already buy sand to replenish their beaches which are carried away by currents. Would a country accept sand for free instead of paying for it, especially in a color and with an environmental impact that would make the beach a popular tourist attraction? I don't see why not.
Moreover a lot of these countries are most directly threatened by sea level rise and ocean acidification.
"The Last 3 Ice Ages Were Caused By Volcanic Rock Weathering Near the Equator [...] Project Vesta seeks to mimic this natural process but to greatly accelerate it because we do not have millions of years to wait."

I'm afraid that too many these proposed geoengineering projects will actually take place, and nobody will really know how much of the CO2 is removed from the atmosphere. If that happens we will end up with another Ice Age (we're due for one soon anyway), or something worse.

I know it's easy to make CO2 the villain, but let's not forget that the life on this planet is not possible without it.

We have ways of measuring CO2 in the atmosphere in ppm. It's recorded daily.

30 billion tons of rock is needed per year. That's non trivial in logistics and cost. You think if it turns out to work too well they'll just keep going year on year until no CO2 is left, and not maybe slow down or stop instead?

I'm not talking about this one project, but multiple projects going on at the same time. And yes we can measure it daily but do we know what's the lag? If we remove 1mln tons of CO2 from the atmosphere today, will it show up in the results tomorrow? If not, do we know how that's going to affect the climate?
You can monitor CO2 real time. And if we ever took too much out, which is vanishingly unlikely: just burn more oil!

You can buy a co2 sensor for $150 or so.

Lol. Im sure $150 co2 sensor will be able to detect co2 concentration in the atmosphere of our planet.

Climat is a very delicate system. Once we remove too much there might not be enough time to reverse this.

In general yes - Outside my co2 sensor shows an accurate enough current planetary co2 level. Watching it is frightening.
So you're looking at the display and instantly you know what the value was last year, and how the seasonal variability affect whatever you see on the display?

Whatever you're reading on your co2 sensor, thermometer, or any other sensor device RIGHT NOW is only indication of what's happening right now, in your location. That's not a global trend, not even a local trend. And having the sensor installed in incorrect place can mean that the data is worth less.

Yes, “lol”, it will. In fact you don't even need to spend US$150. Your ignorance is not a good reason to sneer at people who are doing you the favor of sharing their knowledge with you.
Well, the problem with most of these off the shelf , indoor sensors, is that they are calibrated to current reading of about 400ppm, that's their base. To correctly measure CO2 you will need something that does not depend on that value to self-calibrate. What's more, some of them can have +/- 20ppm or worse accuracy. If the average annual ppm increase is 2ppm you can't reliably see the increase on your home device. To do that you need to have something that's NIST calibrated, with correct accuracy, set in a right place, and gather the data for longer period of time. You will need to smooth the data, and know how to interpret it.

Source: I develop software for data acquisition systems

We are decades into pumping vastly more carbon into the atmosphere than is sustainable. We're not going to accidentally flip that problem upside down without noticing years in advance.
Like we've reacted when scientists told us about rising co2 levels 30 or 40 years ago?
I don't think I understand your position here. Do you believe there is a profit motive to doing this kind of carbon sequestration? As I understand it, it's going to be expensive to do, and require significant money/time/effort to keep doing it. So, what will keep it going in your runaway scenario? Why will people keep mining and moving these materials into place beyond the point where it is necessary to counter our current crisis?
I was talking about possibility of having multiple projects run by different countries/non-profits at the same time, without any coordination, and messing up the climate even more. Why is that so controversial?
I think it's an unpopular opinion because there's no evidence that states will "over-do" any climate action. So far, climate action is almost entirely theoretical. States are doing effectively nothing to counter climate change. One might even argue they're doing less than nothing, by continuing to allow externalizing costs of fossil fuels, animal agriculture, etc.

It seems implausible that there would be too much action on climate change, because there is currently effectively none. Maybe your theory will seem more believable if any major climate action takes place. But, given the costs and current inertia in the other direction, I don't think it is a realistic problem to worry about today.

true, but maybe we're in the mess simply because we don't worry about long term effects of our actions.
Climate change is the result of (mostly) unregulated profit-seeking. Not merely a lack of worry about long-term effects of our actions. It isn't accidental...we knew decades ago that there were consequences, but a few people with a lot of money bought policies ignoring the problem (from willing politicians worldwide).

There is a profit motive behind our climate catastrophe, not "oops, I forgot to turn off the climate change machine when I left the house".

And you don't think there is no profit motive in the current "global warming industry"?
I thought we were having a serious/sincere conversation.
We are - I'm not saying that most people want to do the right thing, but there is also bunch of them that use global warming as a way to make a quick buck. I hope you don't believe that one side of the debate is all good and another one is all bad..
That doesn't make any sense, and I don't see any evidence that people are (or could) use global warming to "make a quick buck".

"I hope you don't believe that one side of the debate is all good and another one is all bad.."

What "sides" do you believe we're talking about here?

I have no doubt that any project that gets scaled will be closely monitored for CO2 and effects locally - governments will want to know they getting something for their money. First to prove it works well enough, that they're not being defrauded by convincing snake oil, and also any unintended consequences no one mentioned.

It took years of the gigatons from burning oil, and the gigatons coming from burning forest and other plant material not being replaced by new growth that got us into this mess. We might be remediating for decades or centuries. Any and all are going to take years to ramp up to required scale - of mining, building, logistics, finance. We should get ample warning.

So long as contracts are written such they can stop when no longer needed... (I believe they'll probably always be needed until the oil is literally finished, but that's entirely different conversation!)

Life on this planet is not possible without nitrogen compounds either. They are also pollutants that can harm people and other living creatures when too much of them enter the atmosphere and water. They were among the first pollutants to be recognized and controlled under the original Clean Air and Clean Water acts. "It's just plant food" is a bad reason to leave emissions of NOx, nitrates, and ammonia unregulated. "It's just plant food" is also a bad reason to leave CO2 emissions unregulated.
If you work backwards, climate change is a giant man-made disaster that literally can only be countered by a just-as-big man-made solution.

Green sand on a beach is like, not as big as millions of cars on roads.

That's not logical. Just because a disaster was made by machines doesn't mean machines are the solution.
"Fewer machines" would be a great solution, which I think might have been the point?
No, I'm saying the scale of the cause of problem vs this guy's tiny sand solution seems out of whack.

Sand won't stop millions of carbon emitting cars on the road. We need bigger solutions.

I have to ask: do you think 30 billion tons of olivine annually is a "tiny sand solution"?
Anyone have a sense of the cost comparison to carbon sequestration via https://carbonengineering.com/
it sounds cheaper, just based on the idea that all you need to do is mine something, move it and spread it.
Interesting! I didn't know olivine was that plentiful.

There is said to be a problem with shortage of construction sand leading to beaches being stripped for sand. So this would solve a secondary problem at the same time.

Yes, olivine is highly abundant, but due to lack of demand, most of it is currently staying underground. We seek to change that.

We are looking for synergies like that, such as covering eroding beaches, breakwaters, etc with olivine.

If you are interested in sand in construction and otherwise, I highly suggest you check out the book The World in a Grain.

The importance of sand in our everyday life blew my mind. I mean the device you are using right now to access this website, has a processor made out of silicon sand, the screen is made of quartz sand. The building you are in is likely made of aggregate sand, and the road to get to your house etc. But also, don't forget that sand was used to make the lenses for reading that made possible for our older academics, extra decades of research and enabled us to carry out astronomy and to create microscopes...

Sand has shaped the world in such a massive way, and we are hoping it can save us from our CO2 problems as well.

https://smile.amazon.com/World-Grain-Story-Transformed-Civil...

Are you selling your olivine operations as CO2 offsets?

If so, how cost effective would that be vs those offsets that are based on planting trees?

a processor made out of silicon sand, the screen is made of quartz sand

The processor is made from silicon, plus trace amounts of aluminum, glass, and other materials. Silicon is smelted from silica, which is silicon dioxide; same difference as hydrogen gas and water, iron and rust, or aluminum and ruby. The common crystalline form of silica is quartz, which is the most common sand (precisely because olivine sand weathers). Most glass, including the glass used in lenses today, is a non-crystalline blend of typically about 80% silica with other materials, largely to lower its Tg. Other sands (notably garnet and aluminum oxide) are important in optics as abrasives. I hope this clears up some of the confusions you are expressing.

Yes, I was just quickly paraphrasing the major takeaways on the impact of sand and its importance in our lives from the excellent book I referenced, The World in a Grain. Here is an excerpt for you and any others interested:

"He rummages through his knapsack, then pulls out a plastic sandwich bag full of white powder. “I hope we don’t get arrested,” he says. “Someone might get the wrong idea.” ... But it’s the mineral in Glover’s bag—snowy white grains, soft as powdered sugar—that is by far the most important these days. It’s quartz, but not just any quartz. Spruce Pine, it turns out, is the source of the purest natural quartz—a species of pristine sand—ever found on Earth. This ultra‑elite deposit of silicon dioxide particles plays a key role in manufacturing the silicon used to make computer chips. In fact, there’s an excellent chance the chip that makes your laptop or cell phone work was made using sand from this obscure Appalachian backwater. “It’s a billion‑dollar industry here,” Glover says with a hooting laugh. “Can’t tell by driving through here. You’d never know it.” ... Most of the world’s sand grains are composed of quartz, which is a form of silicon dioxide, also known as silica. High‑purity silicon dioxide particles are the essential raw materials from which we make computer chips, fiber‑optic cables, and other high‑tech hardware—the physical components on which the virtual world runs. The quantity of quartz used for these products is minuscule compared to the mountains of it used for concrete or land reclamation. But its impact is immeasurable."

https://www.wired.com/story/book-excerpt-science-of-ultra-pu...

If I'm not mistaken, the Earth contains several times as much olivine as it contains crust.
To my no doubt uneducated mind, I am living on the crust so I don't understand what you mean by this statement. Can you explain what the difference is?
The crust is only about 1% of the Earth; most of the Earth's volume is in the mantle. A significant percentage of the mantle is made of olivine.
Dissolving olivine on beaches means releasing nickel into the environment. What is the effect of the release of many megatons of this element?
"massive application of olivine in agriculture may cause imbalances in plant nutrition, notably at low Ca availability, and will bring Ni into the food chain."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3415406/

Super exciting for someone like me who breaks out horribly when a quarter or a nickel belt touches my skin.
Yikes... I know coral and other invertebrates are very sensitive to heavy metals like nickel.
We will be testing the sources of olivine for nickel, and as posted upstream, we have potential solutions for phytomining the olivine reserves for nickel with nickel hyper-accumulating plants, and then burning plants, retrieving the nickel ore and using the proceeds it to further fund operations...
I hope you would still run tests to determine how much left over Nickel is getting into the ocean.

Not just coral will be effected by Nickel, but other important invertebrates as well such as amphipods which play an enormous role in the food chain and health of reef environments.

And we’re talking parts per billion (ppb) when heavy metals can start to become toxic.

And correct me if I’m wrong, but Manganese is another element often found in olivine, which is another metal that can be toxic to marine life.

Yes, we plan to not only run tests on every source before placing the olivine on beaches, but to carry out on-going monitoring with sensors. We are looking for experts in this area (and many others) to help design processes to make sure the olivine weathering is purely beneficial to the marine ecosystem (i.e. deacidification, increasing calcium carbonate levels, and boosting diatoms). You seem passionate about this, if you or someone you know can help us with this please sign up here -> https://projectvesta.org/get-involved/
The dose makes the poison, and in the case of manganese (which is, by the way, not a proper noun), the toxic dose is quite large (unless you're inhaling it), to the point where manganese deficiency is a larger public health problem in humans than manganese poisoning. MnO2 and even the soluble manganese sulfate we use for fertilizer are in the same blue-1 classification as things like alcohol and potassium chloride.

Nickel is a more reasonable concern; nickel sulfate's lethal dose is on the order of 250 mg/kg for humans, so around 10 or 15 grams for an adult. It's not really in the same category as things like mercury, lead, thallium, barium, or even cadmium.

Yes, nickel is more of a concern, but manganese is still toxic. Comparing heavy metal toxicity to human lethal doses can be misleading, however.

Invertebrates are much more sensitive to heavy metals. Again toxic doses for many marine invertebrates are in the ppb-ppm range.

Copper for instance is commonly used as a treatment for marine parasites on fish. However the dosing needs to be done carefully, since a doses in the range of 5ppm can start to kill the fish themselves.

Thank you! Yes, I'm pretty sure nickel is more toxic than copper, including to marine organisms. Where can I learn more?
What's preventing the whole operation from going sideways and spewing pollution? With no economic incentive to do it right, and the impact almost impossible to measure, it could quicky devolve into environmentalism theater.
It's basically impossible to save corals at this point. The oceans will become too warm for them.
We are aware of potential issues with nickel contamination in olivine and will be testing/monitoring for it. Nickel is found in formations of olivine where nickel replaces some of the magnesium ions in their crystal lattices, however, if we do have a large reserve with high content of nickel, we have a technique available to plant nickel hyperaccumulating plants above the crushed olivine to phytomine the nickel content. It is then possible to put the plants in a furnace and get 10% ore back, which we would then sell and use to further fund operations...

"In simple laboratory tests small nickel ingots were produced from the plant ashes. Sowing these plants on appropriate soils and harvesting them at the end of the growing season makes for an environmentally friendly way of recovering nickel. Because these plants extract nickel from the olivine lattice, for every ton of nickel in the plants 330 tons of olivine must weather, equivalent to a capture of 400 tons of CO 2 . Weathering proceeds faster under vegetation. The introduction of this method could revolutionize the nickel mining industry."

See page 8-9 of the Green Cookery Book here for more in-depth information on the technique: https://projectvesta.org/science/#dflip-df_103/9/ Or see this paper specifically on the topic: Schuiling, R.D. (2013) Farming nickel from non-ore deposits, combined with CO2 sequestration.

This is great! Presumably natural olivine outcrops also sometimes produce high nickel levels nearby, no? What are the surrounding ecosystems like?
How long will the plants take to remove the nickel from the Olivine?
I'm a little confused by this, though I see your link picks it out as still speculative.

You're planning to put the olivine on the beaches, the nickel accumulating plants will be planted above. So presumably they'll be as exposed to the action of the sea as the olivine. The document talks of use in poor soils, but no mention of coastal or beach. You've identified species suitable for that level of salt water exposure? If the plants are beyond the high tide mark, won't most of it get into the ocean first?

I read it as the olivine would be mined, plants would be used to extract nickel, and then the olivine would be moved to beaches.
Ah right, so a first pass before it gets to the beach, that makes much more sense now! Though no doubt introduces its own challenges related to how long it needs to sit under foliage before it's beach ready. :)
Reminds me of The Simpsons episode where they let Lizards get rid of the pigeons, then plan to have snakes kill the lizards, then have gorillas eat the snakes. Video: https://www.youtube.com/watch?v=P9yruQM1ggc
Isn't that inspired by Australian experiences with introducing fauna for agricultural needs...?
Yea, I think loosely inspired by Australia's plot to kill sugar cane-ravaging beetles with cane toads (that then became a nuisance).
Jared Diamonds extensively talks about it in his book "Collapse". A good book (not the best one in that category, but good enough to be worth a read).
An odd read that one. A huge distraction at the beginning with pages and pages of "why I bought a house in Montana", and pointedly avoiding any conclusion on Montana's issues. Just share everyone's lengthy perspective. A good book that felt it could have been a great book at half the length.

Out of interest what did you think were the better books in the category?

Can this be targeted to areas with lots of erosion that may welcome a bunch of additional rock/sand as a barrier?

E.g. Florida, New Orleans?

Hey, heads up to anyone associated with Project Vesta... currently your webshop shows an empty store[0].

Also, if executed right then this project could market itself. Travel "influencers" love to show off unique beaches and destinations, and uniquely coloured beaches are always a huge hit. By marketing these beaches appropriately it will generate a lot of attention and (hopefully) a lot of funding for the project.

Good luck! I'll definitely support the project once there are more items in the store.

[0] https://projectvesta.org/shop/

Hi, if you'd like to donate at this point please check out https://projectvesta.org/donate where we currently have our "Grain of Hope" necklace available. It is a single grain of olivine, suspended in a sand timer vial, to symbolize that although time is ticking, it is not too late to stop (and reverse) the damage.

Since we do not have a beach yet where we can place olivine, we were originally not planning to offer the additional jewelry yet. That said, we are seeing demand for additional pieces at this point, so as long as people are clear that we don't have our $25 spent -> 1 ton of olivine on the beach process going yet, and that the donation is going to fund operations and to get our pilot project onto the beach, we will be happy to put them up. For now, I have removed the Cart from the menu, which I am guessing allowed you to work your way to the empty shop :)

And also you are right on target about the beaches and influencers. While we will be working on a top-down policy level with government and other groups to deploy the beaches, the plan is to simultaneously work from the bottom up to create a global movement of people who want to take action on climate change through influencers and ambassadors visiting the beach and also wearing the jewelry to spread the message.

Awesome! Thanks for the response. I will definitely donate once I'm off work today.
Just bought one for my wife!

It would be cool if I could kick in a few extra dollars so you could send one to every female American congressman and senator.

No need to make it a weird gender thing.
May I suggest selling a pound of olivine?

I can see people dumping it individually at the beach for instagram pictures.

I know it wouldn't be effective, but the idea is to raise money while giving people a feeling of participation.

That's the reason those silly 'ocean plastic' recycled 'jewelry' sell so well.

You'd also introduce it as 'normal' before having to deal with bureaucrats.

Setup recurring donations as soon as you get around to it. It's a lot more money, and a lot easier to plan your budget since attrition is perfectly predictable.
Thank you for the feedback, you are right on the mark, as this is our plan once we have our first Impact Beach in operation. The plan is to sell a piece of jewelry for $XX-$XXX and then charge $25 per month, which is about the cost of 1 tonne of olivine. That 1 tonne of olivine placed in the person's name, will remove 1.25 tonnes of CO2 from the atmopshere/ocean, which is approximately equivalent to a US person's monthly CO2 footprint (1.245 t / month or 14.95 t /year)[1]

[1] https://www.weforum.org/agenda/2019/01/chart-of-the-day-thes...

How about a signup-for-updates page/widget? I'd like to donate on a recurring basis, but I may forget to come back whenever you have that sorted out.
This is related to one of my 'scary emergency solutions' governments might adopt if they wake up to the emergency too late: Detonate nukes in shallow bore holes in silicate heavy regions and launch enormous quantities of the stuff into the atmosphere that way.
From the pictures it makes the beach look like its covered in algae or seaweed. I don't think people will be very receptive to the idea if it looks like that.
If it's not sticky and smelly like algae then be it, people will get used to it.
I don't think people will be very receptive to the desolate hellscape that will be the world if we don't do drastic things to mitigate climate change.

I am not saying that this is the solution though.

So far it appears most ppl are looking forward to that desolate hellscape
Even if this is actually feasible and does not have negative environmental impacts, I don't see countries implementing it on their beaches where a lot of tourism is located.

For example in Mexico Riviera Maya, Cancún, Holbox, etc, the main selling point are the white beaches and turquoise sea.

you can overcome a lot of objections with money.
When most beaches are green, white ones will be more valuable real estate.
I didn't read the whole site in detail so maybe i missed it, but does this plan require replacing white sand beaches with green sand, or would it also work to dump green sand on rocky beaches? I don't see too many countries objecting to more sandy beaches.
It might whiten after the CO2 has reacted with it.
Our goal is not to cover up existing tourist beaches. You would be surprised how much coastline around the world is undeveloped and not even accessible by roads etc, those beaches are likely to be the places where we go first.

That said, we believe that green sand beaches will become their own tourist attractions as the naturally occurring ones, such as Papakolea in Hawaii, are (which is the beach pictured on our site). They are beautiful and we are considering ways we could create ecotourism hubs for climate change education etc.

Because most rivers are now damned and sediment flows impeded, many beaches in developed areas are eroding away with no sources of replenishment. Beach replenishment/nourishment is a huge industry and there are not only sand shortages, but even sand mafias who steal sand. So as resorts have to replace their sand, in the future, they might consider creating olivine sand beaches.

We have had early interest from a few parties who own resorts with rocky beaches and would consider replacing their beach with green sand, but at this time, that is not our focus.

We are focused right now on getting a pilot project deployed that can definitively and irrefutably prove the minimum accelerated olivine weathering rate on a real-world, high-energy tropical beach.

The questions of ecotourism and specific beaches is what we will be dealing with as we move to Phase II-III. See an outline of our deployment plan here -> https://projectvesta.org/plan/

[1] https://www.nationalgeographic.com/environment/2019/06/insid... [2] https://smile.amazon.com/World-Grain-Story-Transformed-Civil...

> You would be surprised how much coastline around the world is undeveloped and not even accessible by roads etc

True, but does that apply to tropical coastlines too?

I live in Mexico, even lived in Cancún for a couple of years, the majority of the tropical coastline in the Riviera Maya there is used for touristic purposes.

I don't know the pacific coastline as much but I've been there a couple of times and AFAIK most big beaches are accessible from roads and are accessed by tourists.

Try Honduras or Nicaragua or Guatemala.
Never been there but how much coastline with beaches do these countries have compared to Mexico?

I've been to Costa Rica and there is tourism in a large portion of its beaches. See this map for example on the Pacific Northern coast: https://news.co.cr/wp-content/uploads/2017/04/a-detailed-loo...

A lot of it is completely undeveloped or surrounded by malaria infested jungle or rocky.
Could this save the barrier reef or is it too far out?
Curious question why not also study the naturally occurring green sand beaches in Hawaii?
They do that already and they mention it in comments in this thread. The photo on their website is from there.
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What if we accidentally trigger an ice age.
We can just burn down some forests.
This is a legit worry. The same material we use to stabilize the climate could be the same material that throws it into a negative feedback loop. This happened during the ice age, which is exactly stated in the article.
Okay, no, it's not. You're being silly. We could always fire the Clathrate Gun... (^_^)

But you bring up an interesting point: there's no going back. This really is the Anthropocene Age and we're going to have to manage the planet from now on, now that we can, now that we know.

How am I being silly? Logically if the same conditions caused an Ice age in the past and we take steps to replicate those conditions in the present then this is a genuinely possible outcome. How is this not something to think about?
First, I'm not an expert, maybe you aren't being silly, I don't really know.

Second, this is actually totally something to think about, and it seems to me like matznerd & co. are thinking about this very clearly and scientifically.

The reasons I think it's kind of silly to worry about olivine weathering triggering an ice age is that it seems to me (again, NOT an expert) that we would have enough warning to deal with it, now that we know it's something we have to deal with.

We could put less olivine out than we had planned, or remove some (make it into concrete or something), or even just burn off fuel or release methane to counteract the cooling.

Like I said, you are bringing up an important point: we can no longer pretend that we're not already "geoengineering" our home world.

"We are as Gods, we might as well get good at it."

What happens if we do this but we also reduce planetary carbon emissions in other ways? Will we cause another ice age?
We are so massively far away from being able to do that, it's not worth worrying about. Especially since active carbon capture methods can easily be switched off long before we approached any "dangerous" level.
Olivine beaches cannot be switched off, but you're probably right that the risks are manageable.
You can stop making new olivine beaches. The scale necessary means it would be a long, slow process.
The beaches will continue absorbing CO₂ long after you stop making them. I think this is probably a manageable problem but it's important to recognize that, as with emitting the CO₂ in the first place, the feedback can be a long time in coming, so there is a risk of the system running out of control.
We already have fairly functional knobs for increasing carbon emissions.
Well in that case the combustion engine will earn a second golden age. :-)
This is cool. I’ve thought about carbon sequestration a lot using big nuke plants/solar plants+air liquidification+some plant to distill off and turn the CO2 into like methane or some hydrocarbon. My thought here was put half back in the ground and sell the other half to fund the installation/make sure we don’t run out of hydrocarbons. The olivine process, though, is probably easier because it takes much less infrastructure and is more fire and forget. We need some method for sequestration running at scale now (probably multiple). With the amount of CO2 in the atmosphere already, the amount continuing to go in, and the amount of inaction we’re pretty fucked. The current solution (getting the whole damn world to reduce emissions) is unrealistic. Even if we stop putting more in, it’s already there and we’re already fucked. It’s a day late and a dollar short. The countries willing to face this need some way to save us without the cooperation of the countries with their heads in the sand. Sequestration is a good answer for that.
I'd say this project also has their heads in the sand.
Now I'm curious where I can buy a ton of olivine. I've got $30 in my pocket and would love to build me a giant carbon-scrubbing sandbox.
There are many listings on Alibaba & Aliexpress.
Maybe consider places that sell supplies to metal foundries; olivine sand is used as a refractory in some ferrous casting processes. Or maybe check eBay or Mercadolibre or whatever your local equivalent is. I don't think there's a construction or pottery use for olivine sand, so the usual sand suppliers may not have it.
Let's assume the Pilot is a smashing success, let's also say math works out in some country to do it for 0.2% of their GDP.

How do the logistics of policy adoption work for the first "pilot" country?

1. You would need environmental clearance and the government's own stud(ies) on it. How do you get a government to do this assessment?

2. If you have to get Costa rica(or any listed potentials on the page) to show interest do you go to the Environment Ministry and do a power point and ask "So?".

2.1. Do you get them to do this as part of implementing some climate pledge. And in this case what are you mostly competing with for the fixed size pot of $$?

At least in Costa Rica beaches are already used for private resort beaches (illegal in law, but meh), extracting salt and dumping construction debris or stealing sand. With those antecedents I don't think the government would oppose to do something actually useful.