6 ms·

Also worth to point out Earth needed millions of years to sequester that CO2 we release to atmosphere each year.

jonsen 5y ago
The atmospheric CO2 is not a that slow sequestering process. It has varied considerably over much shorter time periods than “millions of years”. “Carbon dioxide concentrations have varied widely over the Earth's 4.54 billion year history.”: https://en.m.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere https://en.m.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_...
- lmilcin 5y ago
  I guess you don't understand what "sequestering" means. Sequestering is a process where carbon becomes unavailable for biological processes. So you have carbon circulating (present in biomass, returned to atmosphere, then back to biomass, etc.) and you have carbon that is not available for circulation. Carbon in atmosphere is part of circulation. When a supervolcano erupts and emits a bunch of CO2, this adds carbon to atmosphere but then that carbon may very quickly be bound in biomass (for example algae, forests, etc.) This doesn't mean it is sequestered. The algae can die and ferment and forests can burn, releasing CO2 back to atmosphere. Earth has ability to very quickly bind large amounts of CO2 from atmosphere, true. But it does not have ability to sequester it, because as long as the carbon is present in biomass, that biomass can burn or rot and change to methane/CO2. Current coal, oil and gas deposits are due to the fact that at early stages of evolution there was no bacteria that could process some parts of biomass. For example, plants rather than rot would just be covered with more plants and become coal deposits. Today, it is not possible to form new coal or oil deposits, because any biomass would be quickly digested/fermented/rotted before it could be sequestered.
  - FooHentai 5y ago
    The pre-bacteria theory is pretty shaky fyi. There is evidence for relevant biomass-degrading bacteria being ubiquitous at the times of coal/oil formation. A more plausible theory imo is that geological conditions in the paleozoec/mesozoeic era lent themselves to greater fossil fuel formation - greater tectonic activity alone would produce the flooding and interment processes necessary to push significant volumes of biomass down to fuel the process.
    - lmilcin 5y ago
      For a significant mass of biomass to be pushed down it first needs to be present. Have you ever been in a coal mine? Coal deposits can be very thick and can consist of practically pure coal with very little anything else. Our densest forests if suddenly "pushed" (I guess covered by ash or anything else, without loosing carbon) would be millimeters in width.
      - yxhuvud 5y ago
        So why can't peat deposits turn into coal under the right conditions? Those form all the time under certain conditions, but they can sequester a fair amount of biomass.
        dredmorbius 5y ago
        AFAIU they can, but it takes a very long time, as well as depth, pressure, and temperature. (Not my area of expertise.)
      - FooHentai 5y ago
        I'm unclear on how this supports a theory of pre-bacterial formation. Yes I've been in a coal mine. What a strange stat check.
  - dredmorbius 5y ago
    There's a fairly large amount of biomass that does get sequestered. Bogs, swamps, and tundra are particularly prone to this, and peat is effectively a low-grade coal (it played a major role in the development of Holland as well). There is a huge amount of sequestered carbon in such landforms. I don't know how that compares with primordial carbon formations. One factor that seems to have been significant in the formation of the coal belt that runs from the present-day Czech republic through Germany, France, northern Spain, England, and the Apallachians is that this was a region of forest and/or swampland adjacent to mountains (the Appalachians, which are literally older than dirt), with the swamps sinking rapidly into a shallow seabed. That may also have played a major role in depriving the biomass of oxygen which would permit it to rot. My own rampant speculation: even given decomposers capable of breaking down woody plant tissue, it's possible that these were insufficiently numerous, or inefficient, or otherwise limited, in ways that aren't currently relevant, such that decomposition is more efficient and rapid today. Interesting questions. Unlikely to be answered by any of us here soon.
dredmorbius 5y ago
The values from Dukes's paper are illuminating. - The fossil fuels burned in a year represent about 400 years' worth of accumulated ancient biomass. That is, you'd need to capture all the biomass grown for four centuries to give the fuel we consume in one year. - But conversion and preservation aren't perfect. So it took five million years to form just the oil we consume annually (or did in 1997, though values have remained reasonably constant since). That is, only about 0.008% of ancient biomass was stored as petroleum. I don't know the figures for carbon-cycle sequester and release rates, though at best we're looking at centuries to remove what we've put into the atmosphere in decades, if not longer.
- pfdietz 5y ago
  CO2 is mostly sequestered by reaction to form carbonates, not by reduction to biomass, but yes it will take a long time. In the intermediate it will dissolve into the deep ocean (mostly), but even that takes a while.
  - dredmorbius 5y ago
    By chemical / geological processes, or as organic limestone (mostly shellfish / plankton skeleton) deposits?
    - pfdietz 5y ago
      Both? The calcium to make the limestone has to come from somewhere.
      - dredmorbius 5y ago
        I'd consider that biological origin, if not primarily then through an obligate mechanism.
  - zozbot234 5y ago
    This reaction can also be accelerated by crushing basalts and other readily-available rocks to a fine sand/dust, and exposing that to the open air by spreading it over large areas of ground, such as fields or beaches. The process is not cheaper than other kinds of carbon sequestration, but it's definitely comparable and long-term sequestration of the carbon seems especially likely, since we're simply enhancing the existing geological carbon cycle.
deleted 5y ago
[deleted]
creddit 5y ago
Also worth to point out Earthly life existed for millions of years with that CO2 unsequestered ;)
- manachar 5y ago
  Is it really worth pointing this out? Why? This is (mostly) a non-sequitur to any modern discussion about climate, the atmosphere, and its effects on human life and civilization. Life, at this point is used to a particular equilibrium. Sure, life has existed at different equilibriums. But we also know when those equilibriums are massively disturbed (via a great oxygenation event, massive asteroid, major volcanic eruptions, etc.) much of the life dies out (obviously depends on the intensity of the disruption) and it takes many years for life to adjust to and make a new equilibrium. Humanity should be deeply concerned with how deeply we have disrupted the equilibrium, as this disrupts the world and biosphere that sustains us. It might be useful if you're building an argument that humanity will be better off after the current mass extinction event is over. However, I tend to find this point more often leads to a George Carlin-esque cynicism and nihilism about earth being better off without humans (or human civilization) anyways.

The atmospheric CO2 is not a that slow sequestering process. It has varied considerably over much shorter time periods than “millions of years”. “Carbon dioxide concentrations have varied widely over the Earth's 4.54 billion year history.”: https://en.m.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere https://en.m.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_...

lmilcin 5y ago
I guess you don't understand what "sequestering" means. Sequestering is a process where carbon becomes unavailable for biological processes. So you have carbon circulating (present in biomass, returned to atmosphere, then back to biomass, etc.) and you have carbon that is not available for circulation. Carbon in atmosphere is part of circulation. When a supervolcano erupts and emits a bunch of CO2, this adds carbon to atmosphere but then that carbon may very quickly be bound in biomass (for example algae, forests, etc.) This doesn't mean it is sequestered. The algae can die and ferment and forests can burn, releasing CO2 back to atmosphere. Earth has ability to very quickly bind large amounts of CO2 from atmosphere, true. But it does not have ability to sequester it, because as long as the carbon is present in biomass, that biomass can burn or rot and change to methane/CO2. Current coal, oil and gas deposits are due to the fact that at early stages of evolution there was no bacteria that could process some parts of biomass. For example, plants rather than rot would just be covered with more plants and become coal deposits. Today, it is not possible to form new coal or oil deposits, because any biomass would be quickly digested/fermented/rotted before it could be sequestered.
- FooHentai 5y ago
  The pre-bacteria theory is pretty shaky fyi. There is evidence for relevant biomass-degrading bacteria being ubiquitous at the times of coal/oil formation. A more plausible theory imo is that geological conditions in the paleozoec/mesozoeic era lent themselves to greater fossil fuel formation - greater tectonic activity alone would produce the flooding and interment processes necessary to push significant volumes of biomass down to fuel the process.
  - lmilcin 5y ago
    For a significant mass of biomass to be pushed down it first needs to be present. Have you ever been in a coal mine? Coal deposits can be very thick and can consist of practically pure coal with very little anything else. Our densest forests if suddenly "pushed" (I guess covered by ash or anything else, without loosing carbon) would be millimeters in width.
    - yxhuvud 5y ago
      So why can't peat deposits turn into coal under the right conditions? Those form all the time under certain conditions, but they can sequester a fair amount of biomass.
      - dredmorbius 5y ago
        AFAIU they can, but it takes a very long time, as well as depth, pressure, and temperature. (Not my area of expertise.)
    - FooHentai 5y ago
      I'm unclear on how this supports a theory of pre-bacterial formation. Yes I've been in a coal mine. What a strange stat check.
- dredmorbius 5y ago
  There's a fairly large amount of biomass that does get sequestered. Bogs, swamps, and tundra are particularly prone to this, and peat is effectively a low-grade coal (it played a major role in the development of Holland as well). There is a huge amount of sequestered carbon in such landforms. I don't know how that compares with primordial carbon formations. One factor that seems to have been significant in the formation of the coal belt that runs from the present-day Czech republic through Germany, France, northern Spain, England, and the Apallachians is that this was a region of forest and/or swampland adjacent to mountains (the Appalachians, which are literally older than dirt), with the swamps sinking rapidly into a shallow seabed. That may also have played a major role in depriving the biomass of oxygen which would permit it to rot. My own rampant speculation: even given decomposers capable of breaking down woody plant tissue, it's possible that these were insufficiently numerous, or inefficient, or otherwise limited, in ways that aren't currently relevant, such that decomposition is more efficient and rapid today. Interesting questions. Unlikely to be answered by any of us here soon.

dredmorbius 5y ago

The values from Dukes's paper are illuminating. - The fossil fuels burned in a year represent about 400 years' worth of accumulated ancient biomass. That is, you'd need to capture all the biomass grown for four centuries to give the fuel we consume in one year. - But conversion and preservation aren't perfect. So it took five million years to form just the oil we consume annually (or did in 1997, though values have remained reasonably constant since). That is, only about 0.008% of ancient biomass was stored as petroleum. I don't know the figures for carbon-cycle sequester and release rates, though at best we're looking at centuries to remove what we've put into the atmosphere in decades, if not longer.

pfdietz 5y ago
CO2 is mostly sequestered by reaction to form carbonates, not by reduction to biomass, but yes it will take a long time. In the intermediate it will dissolve into the deep ocean (mostly), but even that takes a while.
- dredmorbius 5y ago
  By chemical / geological processes, or as organic limestone (mostly shellfish / plankton skeleton) deposits?
  - pfdietz 5y ago
    Both? The calcium to make the limestone has to come from somewhere.
    - dredmorbius 5y ago
      I'd consider that biological origin, if not primarily then through an obligate mechanism.
- zozbot234 5y ago
  This reaction can also be accelerated by crushing basalts and other readily-available rocks to a fine sand/dust, and exposing that to the open air by spreading it over large areas of ground, such as fields or beaches. The process is not cheaper than other kinds of carbon sequestration, but it's definitely comparable and long-term sequestration of the carbon seems especially likely, since we're simply enhancing the existing geological carbon cycle.

deleted 5y ago

[deleted]

creddit 5y ago

Also worth to point out Earthly life existed for millions of years with that CO2 unsequestered ;)

manachar 5y ago
Is it really worth pointing this out? Why? This is (mostly) a non-sequitur to any modern discussion about climate, the atmosphere, and its effects on human life and civilization. Life, at this point is used to a particular equilibrium. Sure, life has existed at different equilibriums. But we also know when those equilibriums are massively disturbed (via a great oxygenation event, massive asteroid, major volcanic eruptions, etc.) much of the life dies out (obviously depends on the intensity of the disruption) and it takes many years for life to adjust to and make a new equilibrium. Humanity should be deeply concerned with how deeply we have disrupted the equilibrium, as this disrupts the world and biosphere that sustains us. It might be useful if you're building an argument that humanity will be better off after the current mass extinction event is over. However, I tend to find this point more often leads to a George Carlin-esque cynicism and nihilism about earth being better off without humans (or human civilization) anyways.