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I think I read old rainforests and the like are actually carbon neutral because of this. Since the biomass is already at peak capacity, the carbon release from

I think I read old rainforests and the like are actually carbon neutral because of this. Since the biomass is already at peak capacity, the carbon release from decomposition is equal to the carbon sequestration from growth.

reitanqild 9y ago
As long as some of the old trees end up underwater in swamps each year they could bind CO2 for a few thousand years. That said I agree that your basic argument sounds reasonable.
- WalterBright 9y ago
  A lot longer than that. Coal is carbon from ancient trees.
  - reitanqild 9y ago
    Edit: I feel slightly stupid now. That might often be a good sign I think :-)
  - Gravityloss 9y ago
    IIRC that was before wood eating molds evolved. After that biomass hasn't accumulated long term so much anymore. We are eating spoils. Bogs can be wet enough so you can have airless conditions for moss that becomes peat and maybe ultimately can become coal under pressure but it's a really really slow process.
    - Retric 9y ago
      Coal deposits took a long time to be created, so it's hard to tell if they are still being created. Are forests net sequestering 1/1,000,000 of an inch per year of carbon? That would produce a lot of coal over the next 300 million years. Remember, roots can go 100+ feet underground.
    - dredmorbius 9y ago
      Opinions differ on that point. I'm familiar with the lignan/rot hypothesis. Another view is that major coal beds, including those of Appalachia and Europe, formed in subducting marshes at the margins of a rising mountain range. Fossil evidence of decay suggests lignan-persistence alone wasn't sufficient to explain accumulations. I don't know which model is more likely, just sharing the info. http://www.pnas.org/content/early/2016/01/13/1517943113 http://www.pnas.org/content/early/2016/01/13/1517943113 https://www.economist.com/news/science-and-technology/21688700-more-any-other-substance-coal-created-modern-society-what-created https://www.economist.com/news/science-and-technology/216887...
      - larksimian 9y ago
        The lignin/rot delayed evolution hypothesis is just wrong. There were molds that could digest lignin in that period. Furthermore, most of the plant mass didn't depend on lignin. See http://phenomena.nationalgeographic.com/2016/04/06/getting-to-the-root-of-how-earths-massive-coal-seams-formed/ http://phenomena.nationalgeographic.com/2016/04/06/getting-t...
        dredmorbius 9y ago
        That references the same PNAS article I'd posted FYI.

reitanqild 9y ago

As long as some of the old trees end up underwater in swamps each year they could bind CO2 for a few thousand years. That said I agree that your basic argument sounds reasonable.

WalterBright 9y ago
A lot longer than that. Coal is carbon from ancient trees.
- reitanqild 9y ago
  Edit: I feel slightly stupid now. That might often be a good sign I think :-)
- Gravityloss 9y ago
  IIRC that was before wood eating molds evolved. After that biomass hasn't accumulated long term so much anymore. We are eating spoils. Bogs can be wet enough so you can have airless conditions for moss that becomes peat and maybe ultimately can become coal under pressure but it's a really really slow process.
  - Retric 9y ago
    Coal deposits took a long time to be created, so it's hard to tell if they are still being created. Are forests net sequestering 1/1,000,000 of an inch per year of carbon? That would produce a lot of coal over the next 300 million years. Remember, roots can go 100+ feet underground.
  - dredmorbius 9y ago
    Opinions differ on that point. I'm familiar with the lignan/rot hypothesis. Another view is that major coal beds, including those of Appalachia and Europe, formed in subducting marshes at the margins of a rising mountain range. Fossil evidence of decay suggests lignan-persistence alone wasn't sufficient to explain accumulations. I don't know which model is more likely, just sharing the info. http://www.pnas.org/content/early/2016/01/13/1517943113 http://www.pnas.org/content/early/2016/01/13/1517943113 https://www.economist.com/news/science-and-technology/21688700-more-any-other-substance-coal-created-modern-society-what-created https://www.economist.com/news/science-and-technology/216887...
    - larksimian 9y ago
      The lignin/rot delayed evolution hypothesis is just wrong. There were molds that could digest lignin in that period. Furthermore, most of the plant mass didn't depend on lignin. See http://phenomena.nationalgeographic.com/2016/04/06/getting-to-the-root-of-how-earths-massive-coal-seams-formed/ http://phenomena.nationalgeographic.com/2016/04/06/getting-t...
      - dredmorbius 9y ago
        That references the same PNAS article I'd posted FYI.