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Ancient climate change?

  1. wolram

    wolram 3,761
    Gold Member

    Did a catastrophic change in the climate bring about the dark ages?


    In the year 535-536 Byzantine historian Procopius recorded,
    "the sun gave forth light without brightness".
    Tree ring analysis show abnormally little growth in irish oak in 536
    and another sharp drop in 542, similar patterns are recorded in
    Sweden, Finland and Sierra nevada
    In south america drought caused the collapse of the Teotihuacan
    empire.
    In china drought caused the tax base to collapse and destabilized
    the ruling powers
    In other parts of the world plagues broke out killing millions.
    The eruption of the indonesian volcano Krakatoa is the most
    probable trigger for all these events.
     
  2. jcsd
  3. wolram

    wolram 3,761
    Gold Member

    http://www.huttoncommentaries.com/ECNews/SuperVolc/Krakatau/Krakatau1.htm

    A Syrian bishop, John of Ephesis, wrote of certain extraordinary events that occurred in 535-536 A. D., as follows:

    "There was a sign from the Sun, the likes of which had never been seen or reported before. The Sun became dark, and its darkness lasted for about 18 months. Each day, it shown for about four hours and still this light was only a feeble shadow. Everyone declared that the Sun would never recover its full light again."1

    Thus the 535-555 interval began with significant solar darkening and a sudden, significant worldwide temperature decline. Floods and droughts, crop failures, plagues, and famines followed this global cooling of the climate. [Perhaps this is why Cayce readings 3620-1 and 257-254 say that "anyone who can should buy a farm, and buy it if you don't want to grow hungry in some days to come," for "the hardships for [America] have not yet begun, so far as the supply and demand for foods are concerned".]

    Bubonic plague occurred due to the cooler temperatures. This plague massively reduced populations. Traces of sulfate ions, from sulfuric acid produced by the eruption, are found in ice cores from Greenland and Antarctica, ruling out asteroid or comet impacts as the source of the Sun-darkening dust. No wonder that the term Dark Ages is used to describe the physical and societal situations that developed beginning in 535 A.D.
     
  4. wolram

    wolram 3,761
    Gold Member

    http://everything2.com/index.pl?node_id=1158691

    Hence there was a shift in the global climate, harvests failed, there were severe droughts, everything got colder, and the bubonic plague made its first appearance in Constantinople in 542 AD, sweeping fairly rapidly across Europe and hitting Britain in 547 AD. The plague returned at regular intervals afterwards and according to Edward Gibbon lasted for 52 years. The end result being a significant depopulation particularly of what had been the more economically developed parts of the world, such as the Roman Empire and its former territories.

    These events are believed by many to have been a significant factor in such historical events such as the fall of the Gupta empire in India, the Islamic conquests in the Eastern Mediterranean as well as the conquest of Britain by the Anglo-Saxons.
     
  5. wolram

    wolram 3,761
    Gold Member

    http://sunsite.berkeley.edu/OMACL/Anglo/part1.html

    A.D. 538. This year the sun was eclipsed, fourteen days before
    the calends of March, from before morning until nine.

    A.D. 540. This year the sun was eclipsed on the twelfth day
    before the calends of July; and the stars showed themselves full
    nigh half an hour over nine.
     
  6. wolram

    wolram 3,761
    Gold Member

    http://www.newint.org/issue319/cat.htm

    According to historian David Keys, the last time global climate change transformed our planet was back in the sixth century AD, the heart of the Dark Ages. Today climate change is at least partially driven by human agency. But 1,500 years ago it was triggered by a massive volcanic eruption (535 AD) in Southeast Asia (Krakatoa being the likeliest culprit), setting in motion a chain of events which included plague, barbarian migrations and revolution.
     
  7. Evo

    Staff: Mentor

    "Dark Ages" is actually a term that was used to describe the period due to the lack of information, although more information has surfaced recently and the period is commonly refered to as the "Middle Ages" now. Sounds like for 18 months it was truly dark. :tongue:

    There is evidence found in ice core samples that could indicate a volcanic eruption, although it is still speculation. It wasn't Krakatoa, but Krakatoa may have been formed by the explosion.

    "Under a likely scenario, a large volcano, which Wohletz calls proto-Krakatoa, connected the islands of Sumatra and Java. When it erupted and then subsided, it created the Sundra Strait and left a ring of smaller volcanoes, including the present day Krakatoa. The ash, dust and water vapor blown into the stratosphere would disperse across both the Northern and Southern Hemispheres."

    "Although definitive evidence for such a catastrophic eruption has not been discovered, the possibility deserves a full-scale field study, Wohletz said, in part because of the potential impact on the world if another such catastrophe happens."


    http://www.lanl.gov/news/index.php?fuseaction=home.story&story_id=1115
     
  8. interesting. Now if you go here for volcanic tracers in the ice cores:

    Scrolling down you find non zeros for volcanic sulphur:
    BP = Years before 1950. So the real biggy appears to have been in or slightly before 363 AD, whilst 538 AD corresponds with 1412 BP but there is nothing. Instead we see a small spike in 1416BP, 534AD. Now I wonder who got the counting wrong.

    Note also that with steps of a mere two years except for the 1587BP event, the air is clear again within two years, which is not in line with the assumed longer lasting climate changes. A year or two without summer ok, but then things resume as normal.
     
  9. wolram

    wolram 3,761
    Gold Member

    Andre, i do not doubt your figures, if the big one was 363 AD, do you know if
    it was the same event but mis dated to 536 AD, and what about the tree ring
    evidence, is there one for 363AD?
     
  10. fuzzyfelt

    fuzzyfelt 743
    Gold Member

    Why would cooler temperatures cause bubonic plague? I think I remember reading of an interesting cause of the Justinian plague in this catastrophe theory, but I had a feeling it wasn't directly due to the cooler climate, and that the bubonic plague is more likely to occur in warm temperatures. (and that other plagues are indifferent to climate.)
     
  11. Hi Wolram,

    Again, the problem here may be that the impact of the Krakatoa explosion on climate was not that long. Remember only a few years at the most. After all, the number of volcanic particles in the air is not going to chance the time to resettle. We see the same after the recent Mt Pinatoba eruption. The real affected tree rings may be not even be discernible from a few dry years.

    Here is another date:
    http://volcano.und.nodak.edu/vwdocs/volc_images/southeast_asia/indonesia/krakatau.html

    Caldera's usually form after an eruption. Interesting isn't it?
     
  12. wolram

    wolram 3,761
    Gold Member

    If i remember correctly the fleas carried by rats feed more in cold weather,
    some thing to do with blood coagulating in the gut of the flea, but i'm not
    sure if this is correct.
     
  13. wolram

    wolram 3,761
    Gold Member

    Its all ways good to hear from you Andre, you say two years for the particles
    to resettle, do you know how long it would be before agriculture recovered?
     
  14. wolram

    wolram 3,761
    Gold Member

    Is there a record of massive volcanic eruptions, This would be a great way to
    check the dates of historical events?
     
  15. Yes indeed, The so called tephra layes (volcanic microscopic glass particles) are routinely used for dating and much more accurate than carbon dating. The ice cores are dated counting yearly snow layers and some of volcanic records like my previous link can be used to date the volcanic event within a year (provided that you counted the layers correctly). The problem is, which eruption is which though, since the strenght of the ice core signal is highly dependent on the locations and the meteorological conditions. The dating of the Thera volcano is also an interesting controversy. Here you read 1628 BC but my original Antarctic Ice cores link would suggest 1729 BC. There is also a Greenland Volcanixc tracer record but I cant find it back at the moment.
     
  16. fuzzyfelt

    fuzzyfelt 743
    Gold Member

    This mini nuclear winter is believed to have been caused by a comet hitting the earth (Rigby et al 2004) or the eruption of a massive volcano, possibly Krakatoa (Keys 1999). This cold period was accompanied by wetter than usual weather in several parts of Eurasia and was followed by drought (Keys 1999). This disruption of weather could have weakened the population through crop failures and famine, and made the people more susceptible to plague.

    This weather pattern also could have brought wild rodents harboring plague into close contact with rodents associated with human habitation, and thus provided a link to people. Fleas require warm (18-27 °C) moist (greater than 70% humidity) conditions to develop (Harwood and James 1979). The cold temperatures and crop failures of the sixth century would retard flea reproduction outdoors, but also could have driven rats and fleas inside homes and horrea, to warmer temperatures and food sources. The plague is believed to have started in the area around Ethiopia, near a known plague reservoir in an area that is normally fairly dry (Figure 1) (Keys 1999). The increased rain and flooding might also have driven wild rodents from their burrows in or near river banks into close contact with human dwellings and house rodents (Keys 1999).

    Found this that decribes, pretty obvious really, why the cooler weather could have contributed to the plague. As it turns out, thats not really very interesting at all, but it also mentions the recent comet explanation (a comet not much more than half a kilometer across).
     
  17. wolram

    wolram 3,761
    Gold Member

    Fi, what you say is interesting, im pretty sure that comets are ruled out of the
    equation though. It is hard to imagine the effects of a global catastrophe, but
    where is the evidence ?
     
  18. fuzzyfelt

    fuzzyfelt 743
    Gold Member

    Good question, Wolram. I haven't managed linking yet, and haven't read much about them, other than they are using the same evidence of tree rings and the darkenend sun to say that this is consistent with a small comet impact. This was done at Cardiff University, if you wanted to look it up.
     
  19. What also could be consistent with those signs is a small oceanic chathrate decomposition event. A big one has led to the extinction of the Mammoths. I will link to the presentation on the World of Elephants Conference in Hot Spring SD, tomorrow when it's done. A little preview here.

    Linking is simple, fi. Just click the cursor in the address window and copy - paste. If you want to see how other tricks are done :confused: just hit the
    of that post. :rolleyes:
     
  20. wolram

    wolram 3,761
    Gold Member

    http://www.celt.dias.ie/publications/tionol/baillie02.pdf

    From tree rings to Arthur to near miss commet.

    http://www.morien-institute.org/darkages.html

    The Welsh flag depicts the commet, a great read.

    http://www.asnsw.com/universe/1999/tda-0999.htm

    The calculations for the Taurids suggest that we pass through the core of the meteor stream approximately every 2,500 years - today, we are passing through the outer edges. The last two occasions when we passed through the core were in 2200 - 2000 BC and in AD 400 - 600. The epoch around AD 3000 looks like being a fun time too - the Y2K doomsayers can always say they just got the millennium wrong
     
  21. fuzzyfelt

    fuzzyfelt 743
    Gold Member

    http://hnn.us/readcomment.php?id=30188&bheaders=1
    - the comet idea.

    Cool, thanks Andre!


    I look forward to hearing what is said at the conference. The oceanic clathrate is fascinating.
    I couldn't quite work out just how they abruptly change climate - slope slides destabalise the methane?
    Would that mean they would be assossiated with tsunamis? As would the volcano scenario, but not necessarily the comet idea?
     
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