Carbon sinks?

Discussion in 'Environmental Discussion' started by bwilson4web, Aug 30, 2012.

  1. bwilson4web

    bwilson4web BMW i3 and Model 3

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    More for Doug but an open question:

    What are the relative contributions of the modern carbon sinks?
    • ocean bottoms?
    • forests? (are the floors of forests rising?)
    • bogs and swamps? (are there many left?)
    • permafrost cover?
    Just curious if this is the right ranking or is this still subject to study? Wiki seems a little thin on the subject.

    Bob Wilson
     
  2. ForestBeekeeper

    ForestBeekeeper Active Member

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    I do not know about all of those topics. In my region forests are growing each year, and we still have a lot of peat-bog. I harvest some peat each year for home heating. While some out-dated textbooks still classify peat as a 'fossil' [saying that it requires 'thousands of years' for peat to form], it does replenish itself. Sustainable practices of peat harvesting can re-harvest the same bog every 8 years.
     
  3. tochatihu

    tochatihu Senior Member

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    Globally net marine and terrestial sinks are very similar, each about 2 petagrams C per year. This occurs even as (primarily tropical) forests are being cleared equavalent to 1 petagram C per year.

    So the land is sucking it up, but substantial disagreement remains on quite where this is happening. High latitude (temperate and boreal) have looked like strong candidates for a long time. Temperatures and CO2 (plant food) are both up, and the look-down satellites see increasing greeness (chlorophyll). Doesn't work like that in (local/regional) drought years, but elsewhere.

    Permafrost soils are not doing much biology at all but they have the largest soil C pools of all. Except for under Antarctic ice, which looks like the biggest soil C pool of all. This is brand new news from this week, and as you can imagine such soils are scarcely sampled. You gotta drill through the ice first. The authors want to drill many more holes to improve their sampling, but I'm not sure that would be wise. Maybe it creates methane vents?

    As ForestBee said, some peat bogs are accumulating rapidly but I don't know any studies on that. Finally, some tropical forests are clearly accumulating C in live biomass, even during droughts, which is quite interesting.

    At sea, the satellites for sure can tell you where the photosynthesis is happening but this may not be exactly where the most carbon is sinking. I'm not sure that the oceanographers have exactly pinned that down either.

    So globally the picture is not as detailed as we'd like. So many places not sampled. But the US forest service has the net C balance really well defined in the US.

    All this net trapping is half of the fossil carbon burn, so only half of that is remaining in the atmosphere.
     
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I would imagine the existing cold and adjacent ice field would close it up quickly. But you do raise an interesting side effect of arctic sea ice loss. The possibility of "uncorking" methane that otherwise might take a long time to reach the surface.

    Within the range of the experimental data, this makes sense. I'm used to systems that have a finite amount of buffering and even with excessive input over the output, appear to be somewhat stable. The buffer simply holds the excess. But there comes a tipping point where the buffering and sink are no longer sufficient and the input suddenly shows up with a very steep rise and often lead to severe consequences.

    Thanks,
    Bob Wilson
     
  5. tochatihu

    tochatihu Senior Member

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    The half remaining in the atmosphere is a 'closely watched train'. CO2 observatories like Mauna Loa see at a global scale. If C sequestration diminishes somewhere, we need 'that where' studies to identify it. That, or the Orbiting Carbon Observatory satellite that did not achieve orbit.

    For me the Antarctic 'soil C' is amazing because their estimate of it is so large. 20,000 petagrams!? Till last week we were talking about global soul C being 3300 petagrams.

    A handy number to remember is 2 petagrams carbon (in tree, soil, coal, etc.) is about equal to 1 ppm by volume CO2 in the atmosphere. Sometimes people talk about weight of CO2 instead of the weight of carbon alone. THe difference is 44/12= 3.67 Makes the discussions needlessly confusing.
     
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