3 ms·

The atmospheric CO2 is not a that slow sequestering process. It has varied considerably over much shorter time periods than “millions of years”. “Carbon dioxid

by 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.

by jonsen 5y ago

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.