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(disclaimer that I manage a climate research group) There has been quite a lot of interest in Ocean Alkalinity Enhancement (OAE) in the last few years. This i

(disclaimer that I manage a climate research group) There has been quite a lot of interest in Ocean Alkalinity Enhancement (OAE) in the last few years. This is kind of an unfortunate title, as "geoengineering" (while not wrong) has a very negative connotation in non-scientific publications. Presenting OAE as ocean acidification remediation would have been a much nicer way to drive adoption. As a side note, lime can be very problematic under some conditions (parasitic CaCO3 precipitation can cause a net release of CO2). But ultramafic rock is alkaline and everywhere. It tuns out you need approximately one large mountain dissolved into the ocean to reverse climate change (neutralize ocean acidification and causes the ocean to take up any extra CO2 in the atmosphere). Or you can just remove acidity from the ocean using solar power, and pour it on rocks somewhere.

mistrial9 4y ago
thank you for posting! > a very negative connotation in non-scientific publications. yes, after decades in higher ed, I too find a very negative connotation in the field of "geoengineering"
DennisP 4y ago
Um....is anyone working on the two methods you mentioned? If you have any links I'd love to learn more. (And if your climate research group is involved in stuff like this, I'd love to check that out.)
- chris_va 4y ago
  Vesta, Ebb Carbon, Planetary Technologies, Heimdal (YC), some stealth companies, and some academics are looking at OAE directly. (may be missing a few) There are a lot of terrestrial enhanced weathering folks too, where the alkalinity eventually washes into the ocean after being spread on land.
froggychairs 4y ago
I’m really interested in learning more about ocean modifications to enhance its ability to store carbon (not via seaweed farms) or protect life that is fragile to increase acidity levels. Do you have any recommendations for further reading? Feels like everything I real on this topic is either carbon removal or solar geoengineering
- chris_va 4y ago
  This sort of thing? https://iopscience.iop.org/article/10.1088/1748-9326/ac002d/pdf https://iopscience.iop.org/article/10.1088/1748-9326/ac002d/... ... Oceans equilibriate with the atmosphere after a few months (they absorbs more co2 in response to pH/carbonate shift), so one has to keep injecting alkalinity to keep a local ecological effect. The CDR effect is persistent, though.
eloff 4y ago
Are you kidding me? One large mountain? That can’t be true. Why are we collectively losing our shit over climate change when we should just blow up some coastal mountains? This seems eminently doable and a lot cheaper than just moving every city away from the coast, among other things. I feel like there’s some fineprint I’m missing.
- TaylorAlexander 4y ago
  I don’t know the details of this concept but even if it’s true we have to decarbonize our economy or we’ll just have to keep blowing up mountains. Also I presume the parent meant “one mountains worth of lime” and I presume most mountains aren’t pure lime.
  - eloff 4y ago
    We will decarbonize. The only fossil fuel we have in massive abundance is coal, and it’s already not economical for electricity generation. Natural market forces could get us there alone. The problem has always been that it doesn’t get us there fast enough. If we can just mine a mountain worth of lime and dump it in the ocean, that seems simpler and cheaper than trying to move all our coastal cities. Even if we decarbonize at the maximum possible speed, we’ll still have to do that.
    - landemva 4y ago
      What timeframe do you think every coastal city will have to be moved? Is there a reputable hedging market for that outcome?
      - eloff 4y ago
        A few centuries. The biggest sea level rise will be at the end, the effect will be non linear. Long after we decarbonize, sea level will keep rising.
      - adgjlsfhk1 4y ago
        some are a lot earlier than others. New Orleans and Most of Florida are already having problems (especially when a hurricane creates a big storm surge).
photochemsyn 4y ago
I think that 'large mountain estimate' depends heavily on atmosphere-ocean mixing rates, doesn't it? IIRC, ocean circulation takes about ~2000 years to mix the oceans. Ocean acidification is a local near-surface phenomenon caused by the oceans absorbing the higher levels of CO2 and pulling the carbonate equilibrium to the left, so to speak. CO2(atm) <-> (H2CO3) <-> (HCO3)- <-> (CO3)-2 -> CaCO3 precipitate ? I don't know a whole lot about this, but it seems you'd have to keep doing this steadily and gradually for > 100 years (maybe 1000 years) at global scale to get that effect? ...and that's assuming no more fossil fuel combustion was taking place? As a mitigation for coral reefs, oyster beds etc. it seems to have more immediate value.
- chris_va 4y ago
  No, we'd need to dissolve that amount into the mix layer (call it the top 50m, for argument's sake), which takes a few months to equilibriate with the atmosphere through that carbonate chemistry. But, if one managed to do it all at once (not sure how), it would only take a few months. One would want to avoid downwelling regions that get sucked into deep ocean circulation before reaching equilibrium (e.g. the north atlantic), that alkalinity would take a long time to come back up and be useful.
throwaway14356 4y ago
drill spiral tunnels in some mountains and pump water though them.

mistrial9 4y ago

thank you for posting! > a very negative connotation in non-scientific publications. yes, after decades in higher ed, I too find a very negative connotation in the field of "geoengineering"

DennisP 4y ago

Um....is anyone working on the two methods you mentioned? If you have any links I'd love to learn more. (And if your climate research group is involved in stuff like this, I'd love to check that out.)

chris_va 4y ago
Vesta, Ebb Carbon, Planetary Technologies, Heimdal (YC), some stealth companies, and some academics are looking at OAE directly. (may be missing a few) There are a lot of terrestrial enhanced weathering folks too, where the alkalinity eventually washes into the ocean after being spread on land.

froggychairs 4y ago

I’m really interested in learning more about ocean modifications to enhance its ability to store carbon (not via seaweed farms) or protect life that is fragile to increase acidity levels. Do you have any recommendations for further reading? Feels like everything I real on this topic is either carbon removal or solar geoengineering

chris_va 4y ago
This sort of thing? https://iopscience.iop.org/article/10.1088/1748-9326/ac002d/pdf https://iopscience.iop.org/article/10.1088/1748-9326/ac002d/... ... Oceans equilibriate with the atmosphere after a few months (they absorbs more co2 in response to pH/carbonate shift), so one has to keep injecting alkalinity to keep a local ecological effect. The CDR effect is persistent, though.

eloff 4y ago

Are you kidding me? One large mountain? That can’t be true. Why are we collectively losing our shit over climate change when we should just blow up some coastal mountains? This seems eminently doable and a lot cheaper than just moving every city away from the coast, among other things. I feel like there’s some fineprint I’m missing.

TaylorAlexander 4y ago
I don’t know the details of this concept but even if it’s true we have to decarbonize our economy or we’ll just have to keep blowing up mountains. Also I presume the parent meant “one mountains worth of lime” and I presume most mountains aren’t pure lime.
- eloff 4y ago
  We will decarbonize. The only fossil fuel we have in massive abundance is coal, and it’s already not economical for electricity generation. Natural market forces could get us there alone. The problem has always been that it doesn’t get us there fast enough. If we can just mine a mountain worth of lime and dump it in the ocean, that seems simpler and cheaper than trying to move all our coastal cities. Even if we decarbonize at the maximum possible speed, we’ll still have to do that.
  - landemva 4y ago
    What timeframe do you think every coastal city will have to be moved? Is there a reputable hedging market for that outcome?
    - eloff 4y ago
      A few centuries. The biggest sea level rise will be at the end, the effect will be non linear. Long after we decarbonize, sea level will keep rising.
    - adgjlsfhk1 4y ago
      some are a lot earlier than others. New Orleans and Most of Florida are already having problems (especially when a hurricane creates a big storm surge).

photochemsyn 4y ago

I think that 'large mountain estimate' depends heavily on atmosphere-ocean mixing rates, doesn't it? IIRC, ocean circulation takes about ~2000 years to mix the oceans. Ocean acidification is a local near-surface phenomenon caused by the oceans absorbing the higher levels of CO2 and pulling the carbonate equilibrium to the left, so to speak. CO2(atm) <-> (H2CO3) <-> (HCO3)- <-> (CO3)-2 -> CaCO3 precipitate ? I don't know a whole lot about this, but it seems you'd have to keep doing this steadily and gradually for > 100 years (maybe 1000 years) at global scale to get that effect? ...and that's assuming no more fossil fuel combustion was taking place? As a mitigation for coral reefs, oyster beds etc. it seems to have more immediate value.

chris_va 4y ago
No, we'd need to dissolve that amount into the mix layer (call it the top 50m, for argument's sake), which takes a few months to equilibriate with the atmosphere through that carbonate chemistry. But, if one managed to do it all at once (not sure how), it would only take a few months. One would want to avoid downwelling regions that get sucked into deep ocean circulation before reaching equilibrium (e.g. the north atlantic), that alkalinity would take a long time to come back up and be useful.

throwaway14356 4y ago

drill spiral tunnels in some mountains and pump water though them.