Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The mystery interval, the last glacial transition

  1. Aug 27, 2012 #1
    I think I said before that the recent glacial era, the late Pleistocene is actually a string of riddles. One of them is the Mystery interval. As the ice core indications in Antarctica suggested a clear warming around 19-18,000 years ago, the ice cores in Greenland did not show anything. On the contrary, the proxies for temperature appeared to dip at 17,500 years until a very sudden jump up at 14,500 years ago. Originally known as the 'Oldest Dryas' it's now the Mystery Interval, especially because detailed studies on areas give conflicting results (Denton et al 2006)*

    So here is a fresh article about the Mystery Interval:


    Carlie Williams, Benjamin P. Flower and David W. Hastings, 2012, Seasonal Laurentide Ice Sheet melting during the "Mystery Interval" (17.5-14.5 ka), Geology, published online on 9 August 2012 as doi:10.1130/G33279.1

    First impression is that if the Younger Dryas is equally enigmatic, how can you endorse an meltwater rerouting hypothesis, in the face of several conflicting evidence (more later) and other ideas?

    However I'm going to read it carefully, maybe we find a gem.




    *Denton G.H., Broecker, W.S. and Alley, R.B., 2006: The mystery interval 17.5 to 14.5 kyrs ago, PAGES news, 2: 14-16.
     
  2. jcsd
  3. Aug 28, 2012 #2
    To elaborate on the original Mystery Interval problem, this is what I wrote (my personal findings hence) about that some 5 years ago (but nothing was published):

     
  4. Aug 28, 2012 #3
    Did anybody follow that or do I have to translate?

    Anyway, the point is that when you start comparing different studies from the same time frame but from different branches of science, you always seem to get into trouble. Something just must be wrong and the challenge is to figure out what is.

    See also the scientific method.
     
  5. Aug 28, 2012 #4
    We should always remember that the energy arriving at the earth's surface varies considerably from equator to pole and is redistributed from equator to pole by various atmospheric and oceanic processes.

    So is what you are saying is that the climatic variations over the past planet do not match present day distribution patterns?
     
  6. Aug 29, 2012 #5
    No, essentially what I'm saying is that different studies don't add up. Isotopes suggest that it was cold during the mystery interval, not only in the Greenland ice cores but also in speleothems (Lachniet 2009), while ocean foraminifera readings may be somewhere in between, for instance Bernis 2002. However other studies, which I quoted, report rapid deglaciation and warming at higher lattitudes during that period.

    For instance, if you want to contain the thermal energy at the lower lattitudes, it would be rather hard to explain it considering the findings of Hubberten et al 2004 about the "warmest tundra" steppe (LW II) in North Siberia.

    https://dl.dropbox.com/u/22026080/hubberten-fig6.jpg [Broken]

    Note that you'd have to calibrate those carbon dates and the onset at 15,000 years 14C BP is actually about 18300 cal years BP, well before the start of the Mystery interval.

    So if things don't add up, the odds are that one or some of our suppositions are wrong.
     
    Last edited by a moderator: May 6, 2017
  7. Aug 29, 2012 #6
    No I don't want to contain it I'm just observing that if there is evidence of some much warmer zones at higher latitudes (as well as much colder ones?) only a few thousand years ago ie when the land distribution was much as it is today then the energy transport pattern must have been different from what produces today's zones.

    As usual, you have posted a large quantity of technical material (no complaint) that takes some digesting.

    My approach is to try to establish some signposts when going through such to refer to.
     
  8. Aug 29, 2012 #7
    Maybe not, obviously the northern hemisphere glaciation during the Last Glacial Maximum, was rather assymetrical, especially Eurasia,

    https://dl.dropbox.com/u/22026080/hubberten-fig1.jpg [Broken]

    But as far as I know the ice was in rapid retreat thereafter. Obviously the glaciated areas like the UK and Scandinavia are much warmer now, as contrast it appears that Siberia is colder.

    Also mind that glacial readvances have been reported troughout the transition to the Holocene, and certainly not confined to the Mystery Interval and the Younger Dryas, and I'm happy to produce a long list of refs for that, if so desired. Let me upload some writings as a text document later, not to swarm the thread with too many technicalities.

    Anyway it looks a like a conflict between the isotopes versus the other proxies.
     
    Last edited by a moderator: May 6, 2017
  9. Aug 29, 2012 #8
    So my reading of it is that there is this seeming contradiction. Sea temperatures are getting colder, but at the same time the ice is retreating.

    You seem to refute that it was actually getting colder.

    Correct?

    Please.
     
  10. Aug 29, 2012 #9
    That's the idea

    Not me, the paleoclimatological researchers do. I was working on a big paper in 2007, which showed anomalies, warm events during the cold Mystery Interval, and the cold Younger Dryas and cold events during the warm Bolling Allerod interstadial. I dug it up, it's obviously unfinished https://dl.dropbox.com/u/22026080/Paleoclimate_revisited_1_%5B1%5D.doc [Broken] and the https://dl.dropbox.com/u/22026080/REFS%20Paleoclimate_revisited_1_%5B1%5D.doc [Broken]. I'll try to update that soonest, one of the reasons is that the calibration is done with INTCAL04, which is distinctly different from the current INTCAL09 at the Allerod-Younger Dryas transition.

    Yes the scientific method, wasn't that about trying to refute a hypothesis rather than trying to find support for it, (remember the Cargo cult speech of Richard Feynman). Obviously if your isotopes tell that the Mystery Interval was cold, wouldn't you have to try to refute that by investigating all other evidence to see if it contradicts?
     
    Last edited by a moderator: May 6, 2017
  11. Aug 29, 2012 #10
    They don't:

     
  12. Aug 29, 2012 #11
    Thanks, bad first impression.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: The mystery interval, the last glacial transition
  1. Paleao Glacial Confusion (Replies: 17)

  2. Mysterious Mastodon (Replies: 10)

  3. Methane mystery (Replies: 4)

  4. Glacial ice structure (Replies: 7)

  5. The methane mystery (Replies: 11)

Loading...