When The Cold Comes, The World Changes

A rather fascinating and potentially illuminating look at what happened AFTER 536 A.D.

There’s bits in here that I’ve never heard before, and that do seem to explain a fair amount. Such as at about 12 minutes when they describe the way blood clots in fleas.

Seems that it only does that at 25 C / 77 F and below. Above that temperature, the flea just digests the blood and poops out the plague bacteria. Below that temperature, the blood with plague bacteria tends to form a clot that plugs up the digestion, leading to the flea repeatedly biting anything it can to try and eat, but to no benefit. So you get a hoard of ravenous fleas biting anything that moves and spreading plague. Thus it comes in outbreaks during cold times.

The plague started in a normally hot part of Africa, showing that that area must have gotten colder than normal. No real surprise, as the volcano that darkened the skies would bring lots of cold. The implication here is that any big ol’ volcano can cause a new plague to spread across the world. Hopefully we have enough antibiotics in inventory…

I’d also point out (though the video doesn’t) that the population will be more vulnerable to infections not just from poor diet due to crop failures, but also dramatically reduced Vitamin D levels under a few years of blocked sky full of volcanic dust and sulphur dioxide.

At about 19 minutes, they move to Mexico. Here there is a claimed re-dating of the demise of Teotihuacan to 150 years earlier than prior guesses, into just that same volcanic disruption. The wiki corroborates that date, but with an equivocating ‘may have’:


The city is thought to have been established around 100 BC, with major monuments continuously under construction until about 250 AD. The city may have lasted until sometime between the 7th and 8th centuries AD, but its major monuments were sacked and systematically burned around 550 AD.

It does look like the colder oceans resulted in dramatic drought conditions all over Mexico and into California (at a minimum). Part of why I’m heading to where rain is more frequent… As we cool, California gets longer and longer drought periods. During the major drought in the ’70s cold dip, skiing was terrible. I remember walking my skis over hay covered dirt 1/2 way down Mountain Run at Squaw Valley then.

There’s also an interesting connection to British history at about 36 minutes. It is asserted that due to trade patterns, the British Celts were likely having plague problems along with crop failures, which made it easier for the Angles and Saxons to move in.

In general, it looks like a cold plunge tends to destabilize Empires, depose Leaders, and collapse established civilizations. Hunger, disease, and war take over. (Note To Self: Have a good store of food, vitamins, necessary medicines, and means to defend them… Gee, sounds like “prepping”…)

There is also a constant theme of migrations from marginal cold areas, south and west, into warmer areas in Europe. And from marginal dry areas into wetter ones in the American West. I note in passing that during “1800 and froze to death” or “the year without a summer” farmers abandoned farms in the North East and moved to Oklahoma in the land rush. Again a migration from north east to south west.

So it looks to me like the best place to be is America’s Heartland and down in the southern half of it at that. Europeans likely will want to consider being closer to the Mediterranean if possible.

North Africa will likely be a big winner, provided they get enough rain for crops. Unfortunately, it looks like another volcano caused a major drought / famine in Egypt, so it might be a place in trouble if things get cold enough for African drought.


In 1783, Mount Laki, a volcano in Iceland, erupted and caused 9,000 casualties. Scientists at Rutgers University suggested that this eruption caused a drought in northern Africa. This drought diminished the flow of the Nile, so that its annual inundations were insufficient to irrigate the land of Egypt. This event suggests that famines in the Near East could have happened more than once. The Bible, of course, records a similar famine that affected Canaan in Abraham’s time. (Genesis 12 )

We also know that the 4200 kiloyear event was a very cold turn:


How Egypt was felled by famine – in 2180 BC
EARTH 26 January 2002
By Betsy Mason

EVEN ancient Egypt’s mighty pyramid builders were powerless in the face of the famine that helped bring down their civilisation around 2180 BC. Now evidence gleaned from mud deposited by the River Nile suggests that a shift in climate thousands of kilometres to the south was ultimately to blame – and the same or worse could happen today.

The ancient Egyptians depended on the Nile’s annual floods to irrigate their crops. But any change in climate that pushed the African monsoons southwards out of Ethiopia would have been diminished these floods.

Dwindling rains in the Ethiopian highlands would have meant fewer plants to stabilise the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment from the White Nile.

Blue Nile mud has a different isotope signature from that of the White Nile.
So by analysing isotope differences in mud deposited in the Nile Delta, Michael Krom of Leeds University worked out what proportion of sediment came from each branch of the river.

Krom reasons that during periods of drought, the amount of Blue Nile mud in the river would be relatively high. He found that one of these periods, from 4500 to 4200 years ago, immediately predates the fall of the Egypt’s Old Kingdom.

The weakened waters would have been catastrophic for the Egyptians. “Changes that affect food supply don’t have to be very large to have a ripple effect in societies,” says Bill Ryan of the Lamont Doherty Earth Observatory in New York.

So you might have to deal with the huge Egyptian population looking for somewhere to live that has water…

This would have dramatic nearly instant onset in a large volcanic event, or slower decade or so onset in a gradual solar driven cooling as the sun goes quiet.

Then they speculate that the failure of Yemen due to water stress caused Mohammed’s family to move to the Mecca / Medina area, and in the chaos and disruption following the disasters started by the cold shift, set the stage for the rise of Islam.

They then do the usual “tour of horribles” ticking off various volcanoes that might blow any day now (or in reality, any million years now…)

I note in passing that most likely a massive eruption here:

that happened about 40,000 years ago is the most likely proximal cause of the demise of Neanderthals. A thick layer of volcanic ash is just above the layer where their skeletons were found in one of the major cave finds. They were thriving prior, nearly extinct after, and the ash covered from near Spain all the way into near Asia. Exactly their range. No real surprise then that the newest remains are found on the coast of Hispania. They survived in a few isolated pockets remote from the volcanic ash field. Eventually to mingle their genes with the newer arriving “modern” humans both in Europe and in Asia (both Europeans and Asians have some admixture of Neanderthal genes) and the final extinction coming from genetic swamping.

That is still an active volcanic area, and it is still able to cover most of Europe in ash. One hopes it just does more little eruptions and skips The Big One for a few thousand more years…

What is quite clear to me, is that THE two big climate issues are simply this:

1) Major volcanic eruptions. Overnight the world is chaos.
2) Slow drift into the next Ice Age Glacial. As it can have onset in just a decade or two. Slow enough for some adaptation, but fast enough to be devastating to whole regions.

There’s also a third equally catastrophic possibility, but the probability in any one century is low. It is almost certain that a large impact into the ice sheet in Canada caused the Younger Dryas and extinction of the megafauna of North America (along with most of the Clovis People). We could easily have another one of those. But they are fairly rare with 10s of thousands of years between them. There’s also no way to know what part of the planet will get whacked until it is too late to move anywhere.

ALL of these cause collapse and destruction via cold and drought. What is of zero risk is warmth. It brings lush growth and a tropical paradise.

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
This entry was posted in AGW Climate Perspective, Earth Sciences, Emergency Preparation and Risks, History. Bookmark the permalink.

21 Responses to When The Cold Comes, The World Changes

  1. Julian Jones says:

    Thank you EM …

    Do you have any views on pole shift :
    “Every ~12,000 years (and many ~6000 year half-cycles between) there is a major cold event on earth. There is also a magnetic excursion, usually major volcanoes as well, and considerable biosphere stress. This is NOT doomsday, but it is very, VERY bad …”

  2. E.M.Smith says:

    @Julian Jones:

    Not a lot. The big thing for me has just been to realize that “Pole Shift” is a misnomer. What happens is that the fluid flow in the earth can lead to periods of chaotic magnetic structure. You get “multiple poles” scattered all over. It isn’t a period of NO magnetic field and it isn’t a case of N / S just swapping.

    We’ve got a bit of this right now. “The North Pole” is really 2 north poles. We chose the average density between them as “The North Pole”, but in reality one is near Canada the other near Russia. Also, off of Argentina, is a spot where the S pole polarity is trying to swap to N polarity. Magnetic “excursions” are very short periods where this happens but it doesn’t get stuck in any new orientation. On very long time scales, eventually one of the excursions settles in the reversed polarity and we call it a magnetic poll shift or reversal.

    Excursion events typically only last a few thousand to a few tens of thousands of years, and often involve declines in field strength to between 0 and 20% of normal. Unlike full reversals, excursions are generally not recorded around the entire globe. This is certainly due in part to them not registering well in the sedimentary record, but it also seems likely that excursions may not typically extend through the entire global geomagnetic field. There are significant exceptions, however.

    Except for recent periods of the geologic past, it is not well known how frequently geomagnetic excursions occur. Unlike geomagnetic reversals, which are easily detected by the change in field direction, the relatively short-lived excursions can be easily overlooked in long duration, coarsely resolved, records of past geomagnetic field intensity. Present knowledge suggests that they are around ten times more abundant than reversals, with up to 12 excursions documented within the current reversal period Brunhes–Matuyama reversal.

    Seems like they happen often enough that life on the planet is not disrupted much by them. There may be disruption to human society, but we’re more likely to do that to ourselves first (witness the witless Biden and his doings at the behest of Global Oligarchs and China).

    Then there’s the question of which causes what:

    Substantial cosmic impact
    R.A. Muller and D.E. Morris suggests geomagnetic reversal due to very large impact event and following rapid climate change. The impact triggered a little ice age and change of water redistribution more to poles alters the rotation rate of crust and mantle. If the sea-level change is sufficiently large (>10 meters) and rapid (in a few hundred years), then the velocity shear in the liquid core disrupts the convective cells that drive the Earth’s dynamo.

    So does the magnetic change cause the cold, or does the cold lead to shear forces causing the magnetic change?

    Due to the weakening of the magnetic field, particularly during the transition period, greater amounts of radiation would be able to reach the Earth, increasing production of beryllium 10 and levels of carbon 14. However, it is likely that nothing serious would occur, as the human species has certainly lived through at least one such event; Homo erectus and possibly Homo heidelbergensis lived through the Brunhes–Matuyama reversal with no known ill effect, and excursions are shorter-lived and do not result in permanent changes to the magnetic field.

    The major hazard to modern society is likely to be similar to those associated with geomagnetic storms, where satellites and power supplies may be damaged, although compass navigation would also be affected. Some forms of life that are thought to navigate based on magnetic fields may be disrupted, but again it is suggested that these species have survived excursions in the past. Since excursion periods are not always global, any effect might well only be experienced in certain places, with others relatively unaffected. The time period involved could be as little as a century, or as much as 10000 years.

    Possible relationship to climate
    There is evidence that geomagnetic excursions may be associated with episodes of rapid short-term climatic cooling during periods of continental glaciation (ice ages).

    Recent analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years’ timescale in the Cenozoic Era occurring with the common fundamental periodicity of ∼13 Myr during most of the time.

    So with a reversal period in millions of years, I’m not really worried…
    And with excursions being every few 10s of thousands of years, they can’t have had much effect.

    Now could it be that a magnetic excursion causes a cold dip? Maybe. But in the absence of any real evidence and with it being very infrequent and all life on Earth living through lots of them, I just don’t see a reason to worry about it. “Worry no worry before its time. -E.M.Smith” I like to have a worry be fully ripe before ingesting it ;-)

  3. E.M.Smith says:

    Part 2 of that geomagnetic video is interesting. Draws a connection between crossing the galactic current sheet / dust and the 12000 year solar events.

  4. E.M.Smith says:

    Rah roh, as Scooby would say. Looks like the notion of a 12ky crossing of the galactic plane “has issues”:

    It’s pretty impressive that, with a disc 2,000 light-years thick, we’re only about 50 light years away from the galactic equator!

    But this wobbling up-and-down doesn’t happen overnight, or even over the span of many decades. To make one complete trip out of and back into the galactic plane takes about 30 million years. In fact, at the rate we’re moving right now, we won’t cross into the center of the galactic plane for another few hundred thousand years, much less by December of 2012.

    So there’s that…

    I think he’ll need to find some other cause for the 12ky cycle claimed.

    There’s at least one cycle (possibly the 1.4 ky cycle) caused by meteor impact clusters from Encke. Likely bit of it caused both the Younger Dryas (BIG bits) and the Tunguska Event.

    FWIW, most stars similar to the Sun are much more active. It may well be that our present history is just from an abnormally quiet period and that without any external influence, our sun might return to a more moody pattern.

  5. Pingback: When The Cold Comes, The World Changes – Climate Collections

  6. Graeme No.3 says:

    The 4,200 year event (about 2200 B.C.) was widely felt. End of the Egyptian Old Kingdom and the Akkadian empire in the Middle East, but the collapse of stone age life in Orkney (Skara Brae and the Ness of Brodgar) and also the slow end of the Harrapan civilisation in the Indus valley.
    Perhaps not important but with the determination of some in society to drive a return to the Stone Age?

  7. H.R. says:

    In all the history of modern humans, we are now technologically equipped to rapidly respond to climate conditions that wiped out earlier civilizations.

    It also strikes me that, because of the complexities of interconnected global trade, near instantaneous global communications, and the ability to deploy financial resources anywhere, human civilizations are now more vulnerable to collapse due to the whims of a handful of GEBs.

    Also, due to our high technical advancement, we’re now highly vulnerable to collapse, or severe setback, due to a Carrington-type event. Those went pretty much unnoticed when everything was pretty much muscle power aided by steam and water power; not a big deal.

    If we wind up back in the stone age, it will be due to politics and not due to any climate change.

  8. erl happ says:

    I’m all for warmth. I’m sitting here with multiple layers and a blanket wrapped around the lower body. We don’t have to wait for a volcanic eruption to bring on the cold. I describe a long cycle in albedo wrought by change in atmospheric pressure tied to solar activity in todays post:


    I don’t complicate the article by speculating about modes of causation but it seems that:
    The flux in surface pressure that is the result of Polar cyclone activity is dependent on the partial pressure of ozone in the upper two thirds of the atmospheric column at the Antarctic Polar Front and also the ozone content of the descending air inside the Polar Front. This conditions the air density gradient across the front. Low solar activity is associated with enhanced Polar Cyclone activity delivering extreme transfers of atmospheric mass from high latitudes. This is the current condition. Reanalysis data indicates that this process has been gathering strength for seventy years.

    The rotation of the atmosphere in the same direction as the Earth, but faster, seems to be dependent on the magnetic polarity of the solar wind that flips every two solar cycles. And its flipping now. Lowest atmospheric pressure in the Antarctic trough occurs in September. It is at the equinox that the atmosphere couples most strongly with the solar wind.

    As solar activity ramps up over the next two cycles so will the intensity of the solar wind.

    This is like changing gear between forward first, and reverse.

  9. Keith MacDonald says:

    “There’s also an interesting connection to British history at about 36 minutes. It is asserted that due to trade patterns, the British Celts were likely having plague problems along with crop failures, which made it easier for the Angles and Saxons to move in.”

    Maybe that’s half-remembered as a folk memory in King Arthur’s Wasteland?

    “The Wasteland is a Celtic motif that ties the barrenness of a land with a curse that must be lifted by a hero. … In the Arthurian Grail material, the Wasteland’s condition is usually tied to the impotence of its leader. ”

    Impotent leaders in the face of climate change might be a cyclic theme in its own right. :-)

    This might also have been the reason Britons from “the Celtic Fringe” in South West Britain emigrated to what the Romans called Armorica, but because of the Brits it became Brittany. That’s why the Cornish and Breton languages are still very similar, and maybe why there weren’t enough Brits still around to deter migrant / mercenary Angles and Saxons from grabbing the opportunity to become the new Overlords (for c.500 years until the Normans).

    Side note – “Armorica”, the land in the west, not to be confused with “America”, the other land in the west. ;-)

  10. Anthony T Ratliffe says:

    Am I missing something in your first sentence? The grammar implies that you have posted a link to an interesting video, but I don’t see any clickable link.

    Sorry if thus is just my old age showing.


  11. E.M.Smith says:


    Likely my bad. I put that sentence up, then decided I ought to describe the link, that ended up being most of the article and THEN you get to the link / video at the bottom. Assuming you are talking about:

    “A rather fascinating and potentially illuminating look at what happened AFTER 536 A.D.”

    So that “Timeline” video.

  12. Borepatch says:

    The book “Justinian’s Flea” goes into the plague in depth and links it to the volcano. Interesting read.

  13. Interesting item. Here is the forecast for the end of the month in Germany


    Here in the UK we had a sunny but cool April and to date a very wet and cool May. I am still turning our central heating on for at least an hour or two in the evening.

    Now, this is of course ‘merely’ weather. But if we look to History we can pick up on such things that nations are often unprepared, or in other words, do not plan for the unexpected.

    That was so in Singapore in WW2 when it is said the British had their guns pointing the wrong way and the Japanese came from the other way. Probably false, but what was certain is that the British had been expecting a naval assault and therefore most of the shells were aimed to pierce ships not cause maximum damage against land based troops and air attacks.

    So the unexpected AND the wrong weapons coincided.

    Which leads me back to chilly weather.

    We have concocted a vastly expensive Plan “A” in the expectation of remorseless warming and all that would bring with it in its wake.

    But just suppose the weather turns cooler, then after 30 years that becomes the ‘climate?’ So as far as I can see there is no Plan ‘B’ and the consequences of having the wrong weapons and looking the wrong way will then be exposed


  14. E.M.Smith says:

    In California near San Francisco we’ve been having very cold nights. Had to turn the heater on 2 nights ago. Often in May we have “summer like” conditions with days into the 90’s and nights just cool enough to be comfortable. This is a lot cooler than that, and with overcast mornings too.

    It reminds me of what it was like in the early ’70s when some folks here didn’t buy AC for their cars as you never needed it… (Central Valley you did though…)

  15. cdquarles says:

    Seconded. We have had a few nights with overnight lows in the 40s, which is much cooler than average for mid-May. That said, this year is much like 1974 was, where cool shots happened quite late, with the most memorable one being the week before Memorial Day. A system brought in cold air on brisk winds, so no frost. The coolest night saw an overnight low of 34, in. late. May. The strong sun got the afternoon high up to above 70.

  16. The True Nolan says:

    @E.M. “But this wobbling up-and-down doesn’t happen overnight, or even over the span of many decades. To make one complete trip out of and back into the galactic plane takes about 30 million years. In fact, at the rate we’re moving right now, we won’t cross into the center of the galactic plane for another few hundred thousand years, much less by December of 2012.”

    True, but that is not the supposed cause of the 12,000 year cycle. There is a galactic current flow and magnetic field which extends very roughly along the equatorial plane but does not match it exactly. It has a sort of spiral undulation to it (similar to the current flow which our Sun has) which leads to the Solar System crossing the spirals about every 12,000 years. As the Sun passes through the spiral there is an increased amount of galactic dust which may trigger solar instabilities and huge CMEs.

    That at least is my understanding of what is posited.

  17. philjourdan says:

    Twas not a volcano that did in the Neanderthals, it was they did not wear masks. Resident Bumbleshoot said so.

  18. Kneel says:

    “In California near San Francisco we’ve been having very cold nights.”

    We had a very mild summer here Down Under.
    Only a few days over 30C.
    Nothing approaching last years 50C on a couple of days!
    At least no Sydney Summer Ice! (oil from tarmac to surface, add rain = like driving on ice!)
    Autumn has also been cool here – already seeing sub 10C mornings and fogs. I am expecting some frosts when winter hits.
    We actually seem to have changed back from the Great Climate Shift of the ’70’s – seems more like the ’60’s where we had more ‘wet season/dry season’, with stinking hot days (40C+) then a “southerly buster” (nice late afternoon/early evening thunderstorm) in summer, and very little winter rain. Almost tropical style at 37S (Shitney)

  19. tom0mason says:

    Meanwhile some in the US Government want to know how much warming the new mandates will prevent …

    A question that can not be asked too many times… it seems.

  20. H.R. says:

    cdquarles: “We have had a few nights with overnight lows in the 40s, which is much cooler than average for mid-May.”

    In Alabama?!? That’s nutso cold!

    Did you spray around the house with Yeti-B-Gone®?

  21. cdquarles says:

    Yeah, in Alabama. No, I didn’t; but the big high that caused those cool nights has been blocked and is still sitting over us. It has modified some in the strong May sun. Lows recently have been in the 50s and highs in the 80s; which is closer to average. Forecast for the next week, which includes Memorial Day, has us seeing lows in the 60s and highs in the low 90s. This is average, too, though the lows should be closer to 70 than 60. We have had no rain, either, since the gully washer that dropped 3 to 4 inches (a month’s worth) in 24 hours.

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