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Thread: Life and volcanoes

  1. #1 Life and volcanoes 
    Forum Radioactive Isotope skeptic's Avatar
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    Nov 2008
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    From New Scientist, 18 January 2014, page 6

    It appears that evolution has been strongly influenced by volcanoes. The vice versa also applies. The New Scientist 23 November 2013 had an item describing how microorganisms have encouraged volcanic activity, and helped form continents.

    Well, there was a time between 850 and 635 million years ago called the cryogenian era (also known as snowball Earth), when things were so cold that most of the planet was under snow and ice. Life suffered. Then came a slow build up of volcanic activity, as two continents crashed together to form the super-continent Gondwana. Global temperatures rose. Snow and ice melted. Then by 541 million years ago, it became positively salubrious, with all that volcanic CO2 creating a warm greenhouse gas climate.

    This was called the Cambrian era, and life flourished, with all sorts of new kinds evolving. The fossils from that time were far more abundant and varied than earlier fossils. Sadly, it got too warm, and much of that life died out in what we call the 'dead era" of 500 million years ago. Then the volcanoes stopped. Temperatures dropped, and in the Ordovician era, about 480 million years ago, life flourished again.

    We know of the volcanic activity because of zircon crystals in various rock strata. Zircons are made in volcanic eruptions, and they survive unchanged through the eras.

    Life creates volcanoes and volcanoes encourage life (up to a point). The great die off later, at the end of the Permian era, 251 million years ago, was probably due to the harmful effects of excessive vulcanism.

    How do you see this affecting the present day Earth?

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  3. #2  
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    How do you see this affecting the present day Earth?
    Humans are swamping whatever effect vulcanism might have at the moment so it's sort of a moot point.

    We're releasing about 130 times as much CO2 as the current level of vulcanism does, I'm not really sure what we might be able to say until and unless we have some way of distinguishing the small effect within the much larger signal - and noise. It's rather telling that the release of aerosols by volcanoes is treated as noise within the temperature signal rather than as a driver of anything.

    EDIT: Whoops. Forgot a reference Voices: Volcanic versus anthropogenic carbon dioxide: The missing science | EARTH Magazine

    These global volcanic estimates are utterly dwarfed by carbon dioxide emissions from fossil fuel burning, cement production, gas flaring and land use changes; these emissions accounted for some 36,300 million metric tons of carbon dioxide in 2008, according to an international study published in the December 2009 issue of Nature Geoscience.

    Even if you take the highest estimate of volcanic carbon dioxide emissions, at 270 million metric tons per year, human-emitted carbon dioxide levels are more than 130 times higher than volcanic emissions.

    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  4. #3  
    Time Lord Paleoichneum's Avatar
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    Oct 2008
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    Sooooo, still waiting for the data that supports organisms creating volcanoes. correlation is not always causation
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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  5. #4  
    Universal Mind John Galt's Avatar
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    Jul 2005
    Weathering is increased by biological activity, therefore there is more detritus to provide sediments, therefore more sediments are deposited, therefore more sediments are carried into the mantle by subduction, therefore more material is available for partial melting to feed island arc and Andean type vulcanism.
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