Cretaceous sea levels

Discussion in 'Earth Science' started by sculptor, Apr 5, 2020.

  1. sculptor Valued Senior Member

    Messages:
    6,884
    ok
    so
    tell me
    What does adding the prefix bwa to hahahahahaha signify?
    ................
    Is that some sort of pop-culture thing?
     
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  3. origin In a democracy you deserve the leaders you elect. Valued Senior Member

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    It's an attempt to write out the sound of explosive laughter.
     
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  5. billvon Valued Senior Member

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    Sculptor's favorite trick is whataboutism. "Yeah, the temperatures are rising with CO2 concentrations. And yeah, we're emitting the CO2. But whatabout this anomalous data from the MIS 11 data set? And whatabout the depth of the ocean? And whatabout ice ages? And whatabout the K-T boundary climate changes? Can you explain all of that? No? I thought so - you can't explain AGW."
     
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  7. sculptor Valued Senior Member

    Messages:
    6,884
    ok
    so
    Instead of hahahahahaha, or bwahahahahahaha:
    What would you use to indicate a bemused chuckle?
     
  8. exchemist Valued Senior Member

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    9,630
    Ah yes, whataboutery (as we call it on this side of the pond) is a rhetorical tactic of creationists, too.

    Please Register or Log in to view the hidden image!

     
  9. sculptor Valued Senior Member

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    6,884
    It may have escaped your notice, however:
    I did not start this thread so that it could be used as a platform for agw mountebanks.
    (sigh)
     
  10. iceaura Valued Senior Member

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    30,336
    Just one agw mountebank.

    The others are embarrassing to agree with, no? Let's see what kind of thread one can launch without making any definite assertions or asking any clear questions or specifying any particular topic at all.

    Apparently during the Cretaceous there were sea levels - probably a consequence of having continents or something - and people are having a hard time figuring out what they were, all those millions of years ago. So far so good?
     
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  11. sculptor Valued Senior Member

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    6,884
    OK
    Perhaps, in an attempt to gain other's open minded perspectives, I do leave questions too open ended.
    Researchers have found evidence of "milankovitch" cycles dating back many millions of years.
    Researchers coring the earth in the desert south west have found evidence of strong 400 kyr cyclicity.
    Then we see changes in sea level within the cretaceous ---outside of this ice age.
    so
    if the volume of water on earth has remained relatively constant for billions of years.
    and the volume of water in the ocean basins had been changing before this ice age, by commonly 20 meters, and occasionally by up to 100 meters(almost approximating the changes within this ice age)
    Then the trees/plants/soils/lakes/rivers/atmosphere/etc... must have held that water.
    ok so far?
    Then, as the temperate zones march poleward
    Can we approximate the volume of water that will be sequestered in the trees/plants/soils/lakes/rivers/atmosphere/etc... and withheld from the ocean basins?

    give it a try?
     
  12. billvon Valued Senior Member

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    18,273
    Most of it is held in ice.
     
  13. sculptor Valued Senior Member

    Messages:
    6,884
    Yes for today.(most----not quantified?)
    However:
    That is why I went without this ice age to look at sea level fluctuation, and to look for where the rest of the water was during cretaceous sea level lowstands.

    None of the sequestered water was held in ice during the cretaceous!
    Meanwhile we have at least 20 meter sea level fluctuations.

    .........................
    do you not find this interesting?
     
  14. billvon Valued Senior Member

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    18,273
    Why do you think the water went anywhere? A 10C change in ocean temperature (on average) would result in a change in sea level of 21 meters due to thermal expansion/contraction. (assuming an average depth of 3600 meters.) That doesn't seem that fascinating.

    No doubt there were other small effects (atmosphere holds more water, more lakes when there's more rain etc) but thermal expansion was the biggest effect back then (and even today.)
     
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  15. exchemist Valued Senior Member

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    There is also the issue of water held in the rocks of the crust and mantle. Volcanoes emit water, while subduction at plate margins entrains it. I can imagine that variations in intensity of tectonic processes could also alter the amount of water in liquid form at the surface, over geological timescales.
     
  16. iceaura Valued Senior Member

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    30,336
    Of course.
    So have all the climate researchers for decades now.
    Ocean basin configuration, continent configuration, also apply - probably: significantly.

    They were quite a bit different then - notice that he appears to be trying to measure "sea level" not from the center of gravity but with reference to shorelines.

    It is called "sea level rise/fall" rather than "shore level fall/rise" because reasons.
     
    Last edited: Apr 21, 2020

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