RE: Global Carbon Cycle [was RE: Number of carbon atoms in the Earth's biomass]

From: Andrew Clough (aclough@mit.edu)
Date: Thu Jul 24 2003 - 00:00:17 MDT

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    At 09:24 PM 7/23/2003 -0700, you wrote:

    >From:Andrew Clough
    >
    >...When a reduction in atmospheric CO2 progresses far enough, the
    >polar caps grow, and the increased albedo from them further cools the
    >Earth
    >in a runaway process that ends with our planet becoming one big
    >snowball. This seems to have happened several times in the distant
    >past,
    >put with massive death among photosynthesizers, the CO2 released from
    >volcanos (that's where inducted carbon eventually ends up) built up
    >enough
    >to reverse the process...
    >
    >
    >The process you are describing is the sputtering gasping
    >end of life on an earthlike planet. I agree that some
    >carbon can be freed by volcanos, but over the long haul
    >volcanos become ever scarcer, as does the free carbon.
    >
    >For every lifeform we have today, there was something
    >bigger and better in the Jurassic: dinosaurs in place of
    >our lions, for instance, and those big honking dragonflies,
    >oh my! Life was almost finished on this planet when we
    >came along and saved it all. Not Gaia, not an expanded
    >sun, it was technological capable humans. Take a bow,
    >friends, our kind saved the planet.
    >
    >spike

    Ok, you've got a point there about reduced volcanic activity in the future,
    and some quick research reveals that I was probably wrong about the lack of
    Snowballing in "recent" history.

    http://www-eps.harvard.edu/people/faculty/hoffman/snowball_paper.html

    "Could the Earth become a "snowball" in future? For the last million years,
    the Earth has been in its coldest state since the Neoproterozoic. We are
    now living in a relatively warm episode, some 80,000 years from the next
    glacial maximum, but some evidence suggests that each successive glaciation
    over the last several cycles has been getting stronger and stronger."

    Still, it seems absurdly anthropomorphic to claim that we are rushing in to
    save the Earth just in time. When the solar system (and galaxy and...)
    blooms we'll be able to claim credit, but even if every human alive were
    killed off instantly, I bet another species could evolve to intelligence
    before the big ice comes.

    Never attribute to malice what can be explained by stupidity..
    -M.N. Plano

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