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Paleoclimate Proxy problems

  1. Sep 5, 2008 #1
    Many of the old threads here are about ice cores, isotopes, CO2 etc and the problems I see with those. There might be interest in a simple wrap up, what those problems are and rather than linking to old threads I think it might be an idea to use fresh words in an attempt to explain it.

    It may be known that the roots of the climate change hypotheses are in the research of paleo climate. See this elaborate work here.


    I intend to substantiate that the interpretation of indirect paleothermometers, especially isotopes to come to that conclusion is too simple.
  2. jcsd
  3. Sep 6, 2008 #2


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    Alright Andre, we're listening. I finally read that AIP link you often recommend. I read the "Especially" link, not the entire thing, it's pretty big.

    How do you pronounce "loess?" What are some favorite places to find loess for testing?
    An example was George Kukla's study of snail shells and pollen in layers of loess (wind-blown dust) in Czechoslovakia — another study that was designed to investigate gradual shifts, but in which a close look at the data revealed unexpectedly abrupt transitions.
  4. Sep 16, 2008 #3
    Sorry Mk, for the delay, there were other priorities but we'll continue now.

    Have been trying to find the best format, so let's try to start of with showing one of the problems:

    Many publications like this focus on the synchronisation problem of the warming following the last glacial termination between 20,000 and 10,000 years ago as shown here

    It appears that Antarctica (Vostok dD) came out of the ice age first, followed much later by Greenland (GISP-II d18O) and then both had clear dips at different periods.

    Given that land warms faster than sea, this adds to the enigma that the predominant oceanic southern hemisphere was much earlier than the predominantly land northern hemispere to warm up.

    Moreover, since Antarctica is still under a clear ice sheet, why do we think that the ice age ended there?

    Such enigma's would require at least the confirmation of warming - cooling in the time frames as indicated in the graphs with more and different paleo temperature indicators, wouldn't you think?

    To be continued

    BTW Loess sounds like thus
    Last edited: Sep 16, 2008
  5. Sep 17, 2008 #4
    So checking other records, as I suggested, was one of the first things done as Spencer Weart elaborates upon:


    But there was a problem as the last sentence showed. The reliability of the carbon dating. In those days the method hinged on a constant ratio of radiocarbon (14C) in the atmosphere but nothing proved to be more variable than that. Nowadays by comparing counted annual layers (tree rings, coral rings, stratified lake sediments) with their carbon dates we have a robust calibration table showing a difference of a few thousand years in this range of 10 – 20 Ky. Hence those early carbon dates, confirming warm and cold, did not do that all. But science moved on and sort of forgot about these problems.

    So let’s focus on that first deviation period between 17.5 and 14.5 thousand years ago, known as Periglacial or Oldest Dryas when the northern hemisphere seemed to remain as cold as ever while the Antarctic clearly seem to warm and let’s check some recent studies covering that period, in which I converted the carbon dates (Ka BP) to calendar dates (Ka Cal BP) with the INTCAL04 table

    (quote from a draft article which merely sums up the essence of the studies)

    References should be in this list

    Denton et al compile the these problems:
    Obviously the biggest contradiction is that the isotopes of the Greenland ice cores suggested cold whereas the melting ice sheets and the changes in flora suggested warm in the Northern Hemisphere.
    That should have triggered the curiousity, but it hardly did.
    Last edited: Sep 17, 2008
  6. Sep 18, 2008 #5
    So following all those contradictions and there are plenty more, there are several more elements to be covered:

    The second isotope - temperature contradiction period between roughly 12,670 +/- 25 and 11,560 +/-25 calendar year, known as the Younger Dryas. This intensely studied period is sort of a can of worms with much more complex features.

    Alternately we could accept that the many other records on the Northern Hemisphere appear to show the same warming as we see on the Southern hemisphere in the period 17.5 - 14.5 thousand years, which would lead to the more satisfactory contention for now, that the Earth indeed warmed up at both hemispheres simultaneously. This would imply that the isotopes of Greenland are not about temperature.

    In that case it would be opportune to investigate what the isotopes are telling us instead and review the hydrological cycle and it's impact on isotope fractination.

    Lastly, if this is all correct what would a clearer view of these processes mean for the original substantiation of the AGW theory?

    So what next? Any suggestions?
    Last edited: Sep 18, 2008
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