3 ms·

it's hard for me to stay stoic in explaining what I see in this proposal, I wish so hard this were a real solution, but I fail to see more than A) a white wash,

it's hard for me to stay stoic in explaining what I see in this proposal, I wish so hard this were a real solution, but I fail to see more than A) a white wash, B) lip service to environmentalists or C) a way to circumvent current or future carbon emission taxes (unclear to me if dumping emissions as carbonates in the ocean is currently considered emissions or not according to carbon credit legalese) First a thought experiment: consider 2 identical hermetically sealed containers (representing gravitationally sealed atmosphere), each containing an open bottle of water (representing oceans). In container 1 we introduce CO2 in the container, some of which will be absorbed by the water both in dissolved gaseous form and in carbonate form. In container 2 we introduce the same amount of CO2 by adding carbonate into the closed bottle and then open the bottle. After letting both containers seperately settle, they will both have the same equilibrium end state, where the same fraction of CO2 is in the container's air, as dissolved gas in the bottle's water and also in the form of carbonate in the bottle's water. H2O (liquid) + CO2 (gas) <=> H2CO3(solution) I don't contest the chemical facts that these rocks can form carbonates by reacting with CO2. I contest the idea that a new sink is identified. The sink is the same sink that has been known for a long time: the oceans, which are currently absorbing a large part of the emissions. So how is this any different? It's just emissions foisted off as capture?!? Do the investors know this? Who are the investors? I assume some of the investors are perfectly aware and simply big CO2 emitters trying to externalize any taxation back on the public by reclaiming money, and the other investors genuinely intend well but were simply tricked into supporting this scheme...

dmm 8y ago
What they are discussing is simply an acceleration of a natural process: the carbonate-silicate cycle[1]. Silicate rocks are transformed into carbonate rocks through weathering. This captures CO2 from the atmosphere. When carbonate rocks are transformed back into silicates through metamorphosis or magmatism the CO2 is released back into the atmosphere. This definitely has the potentially for the long-term capture of CO2. For example in about 600 million years increased solar output will disrupt the carbonate-silicate cycle, resulting in the increased weathering of rocks and the capture of enough CO2 that C3 plants, which make up 99% of existing plant species, will no longer be able to live on earth. [2] [1] https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cycle https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc... [2] https://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future
- DoctorOetker 8y ago
  The Carbonate Silicate cycle you linked also states: >These dissolved minerals are eventually carried by water to the ocean, where they are used by living organisms such as foraminifera, radiolarians, coccolithopores, and diatoms to create shells of CaCO3 (calcite) or SiO2 (opal) through the reactions Ca2+ (aq) + 2HCO3− (aq) → CaCO3(s) + CO2(g) + H2O(l) (for calcite precipitation) and SiO2(aq) → SiO2(s) (for opal precipitation). Observe how half of the carbon is transformed back into CO2, and of the remaining half most will simply return carbonate after death and it's just a small portion of the latter half that falls to the sea floor to end up buried...
  - dmm 8y ago
    That makes sense, thanks
  - ajnin 8y ago
    Why would the CaCO3 return to carbonate after death ? In the past skeletons of diatoms dropped down to the ocean floors in huge layers which are now limestone rock.
    - DoctorOetker 8y ago
      You are certainly correct that there is limestone rock and that it derives from skeletons of diatoms etc.. Consider this (caricaturized) argument: suppose most artificial mummies are mummified humans, that does not mean most humans end up mummified! please check out the sibling comment by philipkglass, the referenced text has a section on calcite compensation, and the previous section detailing the saturation horizon. At high enough pressure calcite prefers being dissolved again. Consider a calcite diatom cap, close to the beach, since it is above the saturation horizon, it won't dissolve soon, now consider a diatom dropping dead over the mariana trench, so the calcite starts sinking, until it passes the saturation horizon, now the pressure is clearly high enough to prefer being dissolved...
  - philipkglass 8y ago
    As btilly has mentioned a few times, ocean acidification is a major problem because atmospheric CO2 has risen so quickly. It takes a few thousand years for the atmosphere, the upper portion of the ocean, and the deep ocean to reach equilibrium. There is an especially elevated CO2 concentration and corresponding lowered pH in the upper layers because there hasn't been time to reach equilibrium with the larger volumes of water in the deep ocean. These upper layers of the ocean, sadly, are also where the vast majority of ocean life and photosynthetic activity exist. Adding alkalinity to the oceans via accelerated silicate weathering can protect sea life against acidification. More alkalinity in the ocean also increases its absorption capacity for CO2, which reduces warming feedback effects caused by radiative forcing from CO2 in the atmosphere. The ocean contains ~60x as much inorganic carbon as the pre-industrial atmosphere; to draw down the content of the present atmosphere to pre-industrial levels, it would require increasing the dissolved inorganic carbon content of the oceans by less than 1%. Converting some of it to solid carbonate minerals is a nice-to-have but not especially critical, because average residence time of dissolved inorganic carbon is about 200,000 years, which will take us well beyond the age of fossil fuels. https://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/Publications/ZeebeWolfEnclp07.pdf https://www.soest.hawaii.edu/oceanography/faculty/zeebe_file...

dmm 8y ago

What they are discussing is simply an acceleration of a natural process: the carbonate-silicate cycle[1]. Silicate rocks are transformed into carbonate rocks through weathering. This captures CO2 from the atmosphere. When carbonate rocks are transformed back into silicates through metamorphosis or magmatism the CO2 is released back into the atmosphere. This definitely has the potentially for the long-term capture of CO2. For example in about 600 million years increased solar output will disrupt the carbonate-silicate cycle, resulting in the increased weathering of rocks and the capture of enough CO2 that C3 plants, which make up 99% of existing plant species, will no longer be able to live on earth. [2] [1] https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cycle https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc... [2] https://en.wikipedia.org/wiki/Timeline_of_the_far_future https://en.wikipedia.org/wiki/Timeline_of_the_far_future

DoctorOetker 8y ago
The Carbonate Silicate cycle you linked also states: >These dissolved minerals are eventually carried by water to the ocean, where they are used by living organisms such as foraminifera, radiolarians, coccolithopores, and diatoms to create shells of CaCO3 (calcite) or SiO2 (opal) through the reactions Ca2+ (aq) + 2HCO3− (aq) → CaCO3(s) + CO2(g) + H2O(l) (for calcite precipitation) and SiO2(aq) → SiO2(s) (for opal precipitation). Observe how half of the carbon is transformed back into CO2, and of the remaining half most will simply return carbonate after death and it's just a small portion of the latter half that falls to the sea floor to end up buried...
- dmm 8y ago
  That makes sense, thanks
- ajnin 8y ago
  Why would the CaCO3 return to carbonate after death ? In the past skeletons of diatoms dropped down to the ocean floors in huge layers which are now limestone rock.
  - DoctorOetker 8y ago
    You are certainly correct that there is limestone rock and that it derives from skeletons of diatoms etc.. Consider this (caricaturized) argument: suppose most artificial mummies are mummified humans, that does not mean most humans end up mummified! please check out the sibling comment by philipkglass, the referenced text has a section on calcite compensation, and the previous section detailing the saturation horizon. At high enough pressure calcite prefers being dissolved again. Consider a calcite diatom cap, close to the beach, since it is above the saturation horizon, it won't dissolve soon, now consider a diatom dropping dead over the mariana trench, so the calcite starts sinking, until it passes the saturation horizon, now the pressure is clearly high enough to prefer being dissolved...
- philipkglass 8y ago
  As btilly has mentioned a few times, ocean acidification is a major problem because atmospheric CO2 has risen so quickly. It takes a few thousand years for the atmosphere, the upper portion of the ocean, and the deep ocean to reach equilibrium. There is an especially elevated CO2 concentration and corresponding lowered pH in the upper layers because there hasn't been time to reach equilibrium with the larger volumes of water in the deep ocean. These upper layers of the ocean, sadly, are also where the vast majority of ocean life and photosynthetic activity exist. Adding alkalinity to the oceans via accelerated silicate weathering can protect sea life against acidification. More alkalinity in the ocean also increases its absorption capacity for CO2, which reduces warming feedback effects caused by radiative forcing from CO2 in the atmosphere. The ocean contains ~60x as much inorganic carbon as the pre-industrial atmosphere; to draw down the content of the present atmosphere to pre-industrial levels, it would require increasing the dissolved inorganic carbon content of the oceans by less than 1%. Converting some of it to solid carbonate minerals is a nice-to-have but not especially critical, because average residence time of dissolved inorganic carbon is about 200,000 years, which will take us well beyond the age of fossil fuels. https://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/Publications/ZeebeWolfEnclp07.pdf https://www.soest.hawaii.edu/oceanography/faculty/zeebe_file...