536 AD: The Worst Year In History? | Catastrophe | Full Series | Chronicle

[Music] just under 1500 years ago something terrifying happened to the world's climate something nobody could understand the sun began to go dark [Music] rain the color of blood poured from the skies clouds of fine dust enveloped the earth [Music] winter gripped the land for two years then came drought famine plague death whole cities were wiped out civilizations crumbled and nobody knew what had happened [Music] it was a catastrophe a catastrophe that affected millions and millions of people all around the world but what was it [Music] the mid 6th century catastrophe was the most important date in the history of the past two thousand years it really did lay the foundations of the world we live in today [Music] for five years in the attic of his unassuming suburban home david keys a writer on history and archaeology has immersed himself in a worldwide investigation he's consulted over 80 experts on drought famine floods cosmic and ecological disasters epidemics and ancient wars he scoured the annals and chronicles of the 6th and 7th centuries a.d from all over the world his book tells the story of a catastrophic climatic event buried in the heart of the dark ages which keyes believes totally altered the course of history [Music] the mystery which has so tantalized him began at a conference on archaeology in 1994 one particular talk really amazed me it was a lecture given by a dendrochronologist an expert in tree rings called mike bailey and he was giving a a lecture about how all the tree rings in the world um really went haywire somewhere in the middle of the sixth century [Music] thirty years ago when he was a physics student professor mike bailey of queen's university in belfast pioneered a revolutionary idea in a totally different field to his own he devised a computer system which would put trees to scientific use he'd realize that trees had the potential to become the silent witnesses of the world's changing weather going back thousands of years every year trees put on a new layer of growth within the bark these layers show up as rings every ring varies in width a wide ring is a year of good weather a narrow ring a bad year the pattern of wide and narrow rings is distinctive each ring sequence can be matched with the rings of previously felled trees and precisely dated the computer program which matches the patterns of the rings was mike bailey's invention and it's now used by laboratories all over the world over the last 30 years in northern europe a variety of people ver our a variety of laboratories have set out and and worked back from known filling dates taking you back through long ring records of living trees and then overlapping to patterns from historic buildings for example fitting together these sort of long ring patterns going back hundreds and eventually thousands of years [Music] it's by painstakingly analyzing and overlapping the patterns of older and older trees that a complete unbroken record of tree ring widths is built up so you've got this sample with its very clear character change just here when we processed another sample from the same building we could see that it came originally from the same parent tree and you could extend the pattern back from the first sample right back through to the beginning of the sample many many samples have to be analyzed by mike bailey's computer program to get the average width for every year it took 14 years to build up the complete data just for irish oaks this tree record is now telling irish scientists what the weather was like every single year for the last seven and a half thousand years if you think about that that's an astonishing position to be in we can interrogate for any calendar year in the last thousands of years what trees thought of their growth conditions over a big geographical area that information simply didn't exist before but what we're interested in is why did this tree go narrow at this point and narrow again at this point what what what is the environmental information which is actually stored in the patterns david keys went to ireland to see for himself the mysterious sixth century event stored in mike bailey's tree rings yeah shuffle through here david it was 10 years ago that mike bailey noticed his oak rings went abnormally narrow in the mid 6th century a.d signs that something very powerful was stopping the trees growing 5 540 4142 extremely narrow bayley then told keys of similar evidence from europe particularly from a colleague in finland he sees a really abrupt drop in 536 a bit of a recovery in 537-38 and then it drops dramatically into 542 so you begin to see a pattern and that pattern wasn't just confined to ireland and finland by contacting other labs david keyes found that wherever you looked in the world in the mid 6th century trees were having a terrible time foxtail pine rings from the sierra nevada mountains in california showed that 535 536 and 541 were three of the four worst years in the past two millennia in chile fitzroya trees record the greatest summer growth drop of the past 1600 years in siberia a 20-year decline in tree growth in the 530s and 540s was the most serious in the past 1900 years so why were the trees not growing was it dark cold natural pollution or drought for mike bailey the answer lay in a microscopic examination of a 536 a.d oak ring cells normally seen in winter were showing up in summer too colleague in germany sent me this photograph of one of his german oaks the tree puts on a line of these large spring vessels and it then puts on fine cell wood during the the summer and goes dormant then it does again the next year so each year's growth is from the beginning of one line of vessels to the beginning of the next and in this year the year 536 the vessels are enormously small and they're also distributed right through the summer so it's widely reckoned that this phenomenon is due to frost damage the implication from this kind of worldwide evidence was that the weather was extremely cold for long periods in the mid 6th century mike bailey also had archaeological evidence from ireland which backs this up much of the wood that he dated came from crannocks wooden island forts that people built as refuges in times of trouble and clan warfare bailly took keys to the remains of one in loch catherine near omar to look at the submerged timbers that once formed the outer wall my first inkling it was something going on came from timbers specifically from sites like this the mid 6th century marks the beginning of the construction of crannogs bailly believes that this was due to the hostile conditions stemming from the climatic disaster when you look at the overall picture there seems to be about a decade of really bad conditions starting in 536 and running on to the mid 540s at least the implication from lots of bits of evidence is that it was extremely cold and that this reduced sunlight and cold caused crop failures so basically people in an area like this would be forced back onto non-agricultural produce they would be forced to fish they would be forced to uh to hunt and that would put a lot of strain on a population which was used to having agricultural produce to see them through the winters for example so i think things would have been fairly bleak here [Music] keys was now hooked not just by the tree-ring evidence that it was cold but also by the fact that people seem to be suffering too his next step was to see whether there were any written accounts from the time of the climate falling apart [Music] by far the greatest civilization of the sixth century was the roman empire rome had been sacked a hundred years earlier by huns and goths but now the empire was resurgent with a new capital in constantinople once again it was the center of mediterranean culture by contacting classical scholars keys unearthed many highly significant roman accounts of bizarre weather one eyewitness assyrian bishop john of ephesus describes the extraordinary events during the years 535 and 536 a.d there was a sign from the sun the like of a witch had never been seen or reported before the sun became dark and its darkness lasted for 18 months each day it shunned 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 [Music] [Music] historians of the 6th century empire do not usually record climatic events unless they are something really stupendous a natural event like a comet will get mentioned now in the 530s the fact that john mentions a two-year dimming of the sun indicates that it was significant john writing in constantinople mentions it cassiodorus writing in italy he too refers to a dimming of the sun we have had a spring without mildness and a summer without heat the month which should have been maturing the crops have been chilled by north winds rain is denied and the reaper fears new frosts these accounts from the mediterranean and middle east were extraordinary enough but what about the other civilizations of that time keys scoured records from north and south china korea and japan and as it turned out there were out of say well over 30 um sources there were around a dozen which actually refer directly to the dark and sun event or to its consequences to its immediate climatic consequences in 540 the japanese great king wrote food is the basis of the empire yellow gold and ten thousand strings of cash cannot cure hunger what avails a thousand boxes of pearls to him who is starving of cold and the nanshi ancient chronicle of southern china records yellow dust rained down like snow it could be scooped up in handfuls as the research continued i began to realize more and more this disaster had really enveloped the entire world that it just wasn't just a few places but it was virtually everywhere the only question was what was causing it there seemed in my mind only three possible answers to that either an asteroid or a comet or a volcano imagine living in the middle of the 6th century suffering a climatic catastrophe an event so horrendous that trees hardly grew for years and the sun was dimmed whatever it was it would have taken thousands of cubic miles of dust to be hurled into the atmosphere to cause this permanent winter was an asteroid comet strike or volcano responsible [Music] at los alamos the birthplace of the atomic bomb scientists have been studying all the possible atmospheric consequences of nuclear strikes and cosmic collisions we certainly have plenty of evidence that the earth is struck repeatedly by asteroids large and small comets large and small you have to have a big thing that hits the ground in order to have a climate effect extraterrestrial bodies come in all shapes and sizes meteors are small rocks which roam space occasionally hitting planets usually causing little damage asteroids are big meteors when these things hit the earth's surface they explode churning up vast amounts of dust and debris [Music] david keyes asked an astrophysicist to calculate how big an impact would have been needed to generate a climatic catastrophe lasting at least a decade so what we can say is that the total number of particles in the atmosphere because this is not one then rho is around one over kappa l to cause a major climatic catastrophe that would last decades we would need an impact by a rather large asteroid say four kilometers across [Music] it would take an even bigger comet to create the same effect a comet consists mainly of gas and ice this gives them their distinctive tail as they move across the sky because they're less dense alan fitzsimmons has calculated that it would take a six kilometer wide comet to affect our climate such a crash would have a spectacular effect on our planet when it was just over two days from impact it would only be seen as a very faint star in the night sky now as it approached us as it got closer and closer we'd slowly see it brighten and grow larger until about 30 minutes before impact it would be about the brightest thing in the sky and by then of course we believe everybody would have noticed it but we wouldn't be able to do anything about it now the time it takes for that asteroid to travel from the top of the earth's atmosphere until it reaches sea level is only eight seconds so we'd see this brilliant fireball all the time of course making no sound because it's traveling about 20 times the speed of sound the first sound we would hear would occur minutes after we see the huge flash of light when the asteroid strikes the earth's surface and is instantly vaporized in a ginormous fireball could this disaster have happened without at least one civilization noticing and reporting it no civilization at the time records any such event in addition scientists have found no evidence of a crater left by an impact from the 6th century i mean that's that's just yesterday in geologic time it'd be a big crater we'd know about it certainly that happened 65 million years ago when the dinosaurs died but i don't think it happened in the 6th century but the lack of a crater alone does not rule out a comet or asteroid strike seventy percent of the earth is covered in water could it be that the impact was on the oceans if the asteroid landed in the ocean then that the initial wave caused by the impact would be miles high there would have been humongous tidal waves big huge tidal waves that that would have swamped the coasts for over the margins of whatever ocean it struck the tidal damage would have traveled miles inland again no civilization recorded such an event and scientists haven't detected any significant interruption to the growth of coastal plants at this period there doesn't appear to be any evidence of an asteroid or comet strike on earth at this time the search seemed to be narrowing down to a volcano but could there be another extraterrestrial explanation this time not a complete comet hitting the earth but one which had fragmented and scattered throughout the atmosphere it's a theory mike bailey suggested to david keyes well the bombardment event has been like classically defined as a large number of pieces of comet arriving in a short period of time and exploding in the atmosphere and the model for that is the 1908 tunguska impact over siberia which was a single object which probably caused about a 20 megaton equivalent size explosion the 1908 tunguska event was an example of an airburst explosion a lightweight meteor hit the earth's atmosphere and exploded in the air while the shockwave caused massive local destruction there weren't enough microfine particles released to affect the weather but mike bailey believes that a whole shower of cometary debris hitting in a tunguska style event could affect the climate if you have a large number of those you're going to just put a lot of material into the atmosphere and you're going to cause a dust fail mike bailey believes that it's possible to use mythology to support his theory he's analyzed the life and death of one of the most famous legends of all time and reached an intriguing conclusion sixth century britain was supposedly the time of king arthur all the many later legends tell that arthur lived in the west of britain and that as he grew old his kingdom was reduced to a wasteland curiously the legends give the date of arthur's death as 539 or 542 a.d right in the middle of the climatic catastrophe the legends also tell of terrible blows which rain down from the skies onto arthur's people mike bailey thinks that arthur's death could therefore be a symbol of something that really did happen devastation by a comet as it shattered and crashed into earth [Music] then you look at the mythology you discover that arthur isn't just an you know somebody with a nice suit of shining armor and some body sitting around a round table the origins of the stories are in celtic mythology and that one of the key figures that you can trace him back to would be the celtic god lug that luge is a bright solar deity who curiously comes up in the west and has a long arm which could well be the description of a comet and luge also is famous for delivering these terrible blows could bailey's myths hold a grain of truth by process of elimination it now seemed to come down to a clear choice cometary bombardment or a volcano but which david keys discovered that there was one hostile area of the earth which could just hold the final clue the polar ice caps [Music] for the past decade a multinational team of scientists has been extracting 1 000 meter deep columns of ice from greenland in the north and the antarctic in the south in the same way trees put on a new ring of growth each season the polar ice caps put on a fresh layer of snow and in each layer is a record of what was in our atmosphere [Music] the chemistry of the old atmosphere is in there and even the chemistry today is changing in our atmosphere if we combine this we can have a record which we can compare with other records from the deep sea sediments from tree rings from lakes but the fantastic thing about the ice caps is that they are directly related to the atmosphere itself professor hammer's team are testing a new greenland core from the 530s a.d that has just arrived at their laboratory if pieces of a comet or asteroid had exploded in the atmosphere the team would expect to find traces of rare chemical elements like iridium if there had been a massive volcanic eruption they would expect to find an excess of sulfuric acid the telltale signature of a volcano the sulfates would have been hurled up into the atmosphere by the explosion and scattered by the winds they would have then got into rain and snow to be finally stored at the poles as ice and what we are going to do now is take a piece of ice out around 5 35 after christ we will have to clean it a little roughly here first we will now bring it into this setup here where it will be cleaned in the end and on all sides and then it will be cut by the steel knife so that we are not touching the core we have to remove quite a lot to be sure that we don't have any ice outside contamination the cleaned core is sliced into five centimeter lengths each length is then melted and analyzed they will be measured one at a time automatically from now on and the results will show up on this computer as chromatograms so what does the ice contain cometary debris or volcanic sulfates i can see the sulfate peak is increasing when i go to the next sample that must be come from sulfuric acid in the atmosphere and that's an indication that it has been a volcanic eruption and as the final result shows it wasn't just any eruption i'll show you here is the sulfuric acid and actually these huge amount of sulfate here lasting several years and clearly higher than anything else in this part of the record corresponds exactly to this around 535 so there's no doubt it's a major eruption the evidence from greenland seemed conclusive lots of sulfates and no cometary debris but for the eruption to have had worldwide consequences more was needed if you want a climatic important major eruption it must show up with a large signal in both hemispheres that is you might see it in antarctic ice cores and you must see it in greenland at the moment information from the antarctic ice core is less precise but from their existing data professor hammer's team already know that there is a volcanic signal in the antarctic too we have a volcanic signal which lasts several years we have from an antarctic core similar evidence as in greenland but not as good not as well dated but indicating that this volcanic eruption could have taken place the data from both the north and south poles is the same a huge sulfur spike around the mid 6th century that strongly suggests volcanic ash caused the global climate damage seen in tree rings the idea of volcanoes causing climatic catastrophe may seem unfamiliar but tree rings and ice cores now show that every thousand or so years massive climate downturns have happened the mid 6th century event is simply the most recent in fact what surprises volcanologists is how few volcanic eruptions there have been in the last hundred years one of the amazing things which people sometimes forget even scientists is that our century is one of the most quiet centuries with respect to volcanism if you go back in time in 19th century and 17th century 18th century there's a lot of volcanics they come in lumps say 20 30 years a lot of them they even overlap in the stratosphere mixing up and it's not speculation but people do think that turner's paintings with his sunsets it was not the taste of the artist to make them so red as they were but they were actually painted in a time when the real sunset looked like that [Music] we live on this planet with over 200 active volcanoes they may have been quiet recently but a really massive eruption can turn the climate upside down to create a dust veil that spreads all around the world the eruption has to happen near the equator as only equatorial winds can spread dust over both hemispheres but there are over 90 equatorial volcanoes could david keyes discover which one caused the mayhem of the sixth century [Music] david keyes began to narrow the search for the 6th century volcano he knew that the highest concentration by far of large tropical volcanoes lies in an arc straddling southeast asia from india through sumatra java the philippines and japan first he turned to the greatest civilization near this area which was then producing written records china i in great excitement started looking to see there was any trace of anything happening in 535 and in fact in february 535 there's a record of a loud bang a huge thunderous sound coming from the south west and with this one there was no mention of lightning or anything it was merely rather sort of mysterious entry in which they only referred to the sort of thunderous noise and interestingly that points straight towards that indonesian area where all those volcanoes are for the chinese to have bothered to record such a sound it must have been an exceptional one-off event but could the sound of a volcanic eruption have traveled the 3000 miles from indonesia to china to help locate the volcano keys asked experts at los alamos laboratory in new mexico to explain the physics of long-range sound travel we know that near the volcano the sudden explosive eruption provides a shock wave in the near field and that propagates out going out to thousands of miles but as it propagates out you lose the high frequencies the shock very sudden sharp reports of the volcanoes and all you're left with are the low frequencies that we measure in what we call infrasound which is generally below 10 cycles per second the long range perception of that sound would be very low rumbling much like very distant thunder the los alamos experts had said it was possible now could keys find any written evidence from indonesia [Music] hey [Music] unfortunately very little writing survives from the area but once again he found a fascinating clue housed in the royal palace at solo in central java is a massive set of manuscript volumes called the book of kings put together in the 1850s but based on ancient sources it describes an extraordinary event which took place around the middle of the first millennium a.d today's javanese royal archivist prince pooja reads from the original text a mighty thunder which was answered by a furious shaking of the earth pitch darkness thunder and lightning and then came forth a furious gale together with a hard rain a deadly storm darkening the entire world in no time there came a great flood when the water subsided it could be seen that the island of java had been split in two thus creating the island of sumatra had keys struck gold with the book of kings geophysicists he consulted said the story accurately described a major volcanic eruption and would have been difficult to invent but which of the many indonesian volcanoes was the book of kings describing there was a clue the only major volcano in that specific area between the islands of sumatra and java is the legendary krakatoa the world's most notorious volcano which last erupted in 1883 but could keys prove krakatoa was the culprit an icelandic volcanologist professor harold sigurdsson now working in the usa joined the chase he had visited the volcano many times and already knew that krakatoa contained an ancient mystery an eruption long ago far bigger than anything recorded in modern times uh about five years ago when we were doing research on the 1883 volcanic eruption of krakatoa we discovered this deposit of a major eruption and so we became very interested in this deposit but at the time we didn't have the time and resources to study it in detail so what we really want to do is ideally find charcoal within this layer or charcoal immediately above and immediately below it in order to give us a date of the event it was an irresistible temptation david keys's ingenuity had led us this far we had to go on channel 4 decided to finance an expedition to java by professor sigurdsson his goal to test keys theory by dating krakatoa's major eruption [Music] krakatoa is part of a group of uninhabited rainforest islands lying west of java and just south of the equator it's also the scene of the most famous volcanic eruption of recent times in 1883 krakatoa blew itself apart killing 36 000 people on the mainland the first stop for professor sigurdsson and his team will be the island of anak krakatoa meaning child of krakatoa anak has formed entirely since the eruption of 1883 and grown up into a thousand foot high volcanic island each year anak becomes ever bigger and ever more dangerous now actually when you get up to them these rocks are the size of houses and uh five six meters in diameter and these were ejected by the explosions of anak and they travel through the air like a bomb basically and they fall to the ground and when they hit the ground they create a crater well this is about as big as they come this one must be two meters high and what do you think about four meters wide yeah i'd say so that's a big bomb huh beautiful crop hard to imagine this thing flying through the air and landing here during an explosion plunking down and creating this crater that it sits in this one is a good one because you can hide behind it in an explosion and take shelter let's hope they don't land like this today it'll be very dangerous anak krakatoa is a noisy and quarrelsome child only two hours after the team pushed off from the island anak let rip hurtling rocks and lava onto the area where we had stood from the safety of the sea it was possible to gaze back at one of the greatest firework shows on earth this activity is just part of a cycle that's been going on for hundreds of thousands of years krakatoa grows up out of the sea every little eruption adds more and more rock to the island eventually it gets so large it blows itself apart this time anak continued its barrage throughout the night on into the heat and dust of the next tropical morning but sigurdsson's task is to journey back in time hundreds of years back long before anna krakatoa was born for decades scientists have thought that krakatoa contains a centuries-old secret illustrations from a 1920s book show a possible pattern first there was ancient krakatoa which exploded possibly around 535 leaving islands behind which eventually with occasional minor eruptions grew back to the krakatoa of 1883 this in turn blew up leaving the krakatoa islands of today sigurdsson's last survey of the island seems to confirm this five years ago he charted the ocean floor using sonar the charts show the outlines of a caldera the term for a giant crater left after a massive volcanic explosion there's a structure out here in the ocean a circular structure which is much larger in diameter and it is possible that this buried feature circular feature that we see here to the north and the east may in fact be a gigantic ancient caldera crocodile well it must be right on the edge here so can sigurdsson find any hard evidence to date this eruption of ancient krakatoa such evidence is only contained in charcoal which is formed when hot lava instantly carbonizes trees the charcoal can then be carbon dated in the laboratory to get an exact date sigurdsson must find charcoal from the major eruption layer which is on the islands around anak krakatoa it's a vertical drop failing that he could also narrow the margin if he finds charcoal in the layers above and below looking for charcoal is like looking for a needle in a haystack and a lot more dangerous i'm right in the middle of the uh this major pyroclastic deposit that is formed by a very large eruption of krakatoa now this is very likely to be the deposit that was created by a uh eruption possibly in the sixth century a.d and this is the one i'd really like to get some charcoal from so we can date this very important event now we'd be very lucky to find charcoal but i'm going to keep digging around here a little bit and see what we got the material in the layers of krakatoa spans hundreds of thousands of years even narrowing down the date of the major ancient eruption to within a few thousand years would be a big stride forward often it's extremely difficult to find the charcoal you might think that would be a lot of burnt wood or carbonized trees here because it's a tropical environment but many volcanoes are barren because there's so much activity that the vegetation and the forest doesn't really get established we've had a lot of problem with finding charcoal in this particular deposit but we must keep in mind that there are only small pieces of the island sticking up above sea level so we have very small area to prospect during the fortnight he was in krakatoa professor sigurdsson was only able to find 10 charcoal samples he was unable to find a charcoal sample big enough to date from the major eruption layer however he was able to find good samples for the layer immediately above it and a layer a few levels below it it will now be possible to see whether 535 falls between those dates if it does not david keys's theory will fall [Music] six weeks later the carbon dating analysis is completed professor sigurdsson faxes the results and an accompanying report to david keyes yeah so what's this assessment that's it's really good news the results show that the layer immediately above the major eruption is dated as 1215 a.d a layer several layers below it is dated as 6600 bc [Music] well if we look at this in detail over here then we have this picture we have 1215 80 right on top here in in in this deposit then we have the the major eruption deposit right underneath it and then we have about five layers and then down here we have the charcoal that we dated at 6 600 bc so in here we have quite a a a period of activity and development of the volcano possibly several thousand years and that leads us to think that the event is much closer to 12 15 80 as opposed to 6600 that span still covers the 535 ad event so it doesn't rule it out at all in fact i think as a result of this we are focusing more and more in on that time frame he thinks that the the the lead period the lead option if you like for when the major eruption that we're talking about took place was the first millennium a d so although technically can be anything between 6 600 bc and 1300 ad all the other pieces of evidence that he's got suggest that it's actually we can narrow that down to the period let's say zero to one thousand our 535 is marvelously right in the middle of that window so i think that it's looking good [Music] david keys's five years of detective work suggests that there is overwhelming evidence of a massive volcanic eruption around 535 a.d in the tropics krakatoa is now the most likely culprit the volcano that did go up in 535 a.d would have produced a dust cloud that enveloped the world it would have been one of the most dangerous spectacles ever seen a 30 mile high column of ash and dust brought global climatic catastrophe darkness drought frost and famine and ultimately chaos and war it was a natural catastrophe that would change the course of human history [Music] in 5 35 a.d scientific evidence suggests that a massive volcano erupted in the tropics it threw up so much ash that it turned summer to winter crops failed for years drought and famine gripped the land millions died [Music] for the last five years david keyes a writer on history and archaeology has immersed himself in this worldwide climatic catastrophe by consulting historians scientists and in particular volcanologists keys has concluded that the most likely culprit was the notorious volcano krakatoa an expedition to krakatoa which lies off the coast of indonesia further supported his theory but keyes believes that the eruption the biggest in the last 1500 years was only the beginning what followed was over a hundred years of upheaval that would change the course of human history forever [Music] so what would the volcanic eruption of one and a half thousand years ago have been like [Music] the amount of power generated by this eruption would have been equivalent to around 2 000 million hiroshima sized nuclear bombs the eruption of this ancient krakatoa is something mankind has never witnessed perhaps tens hundreds of times larger than any volcano that's ever been witnessed david keyes asked volcanologist dr ken willets an expert on krakatoa to feed all the available data about 6th century climate change into a supercomputer to simulate how the explosion began to unfold [Music] i will start the simulation and will show several phases of the eruption wallets has located the eruption in the sunda straits between java and sumatra by combining tree ring and ice core data with eyewitness accounts of the dimming of the sun it's possible to estimate how much material might have been thrown up into the earth's atmosphere with that figure it's possible to calculate the scale and power of the explosion and associated after effects using wallets model we have reconstructed the krakatoa 535ad big bang a giant red-hot fountain of molten rock and a vast cloud of ash towered over the countryside then a second crack would have led seawater in this caused an absolutely vast explosion creating a 30-mile high fountain of magma dust and ash up to a thousand miles away ash rained down on forests and fields the towering clouds of steam and gas and ash pierced them and shot upwards and at times when it seemed like could not go no higher it would continue to go high eventually to the point where it started to block out the sun in all directions and this gray white cloud would then start see to sort of move laterally across the sky like a mushroom cloud [Music] the fallout from the eruption would have been the natural equivalent of nuclear winter [Music] so how did krakatoa affect the world ken wallets has studied krakatoa in detail and he can see similarities between it and a huge dormant volcano near his laboratory high in the hills of new mexico the 15 mile wide volcanic crater or caldera at valle grande new mexico last exploded a million years ago ash from here landed as far away as louisiana using the remains of valle grande ken shows how high-flying volcanic ash blocks out the sun this is ultra fine volcanic ash formed by freedom plenty of eruptions similar to what we think happened in the 6th century at krakatoa it's so fine that even just a baby's breath of air will keep it suspended by my new turbulence it will never fall to the earth as long as the air is moving which of course it always does high up in the atmosphere in 535 a.d similar microscopic particles of ash and sulfur dioxide from krakatoa would have shrouded the whole sky turning it endlessly gray temperatures dropped without the full strength of the sun to heat the oceans less water would have evaporated and the atmosphere became drier and drier as a result would have been progressively less rainfall as a result there were droughts and famines [Music] very often at the end of major droughts you do get massive floods and that seems to have been what occurred but what fascinated david keys most was not the climatic catastrophe itself but the possible effects on human civilization [Music] i began to think to myself well disruption as severe as this has got to have political consequences it's really the long-term consequences that i was interested in in isolating to see whether one big event can actually have a knock-on effect throughout history worldwide keys decided to examine a series of historical puzzles of the 6th century a.d he looked at events which from contemporary writings and archaeological evidence were known to have taken place but whose cause has never been properly explained the first puzzle was the spread of a terrible disease which brought the greatest superpower of the time the roman empire to its knees in 535 a.d under the emperor justinian the late roman empire based in constantinople was flourishing but in 542 a.d something awful struck at the heart of justinian's glittering empire the horrors were described by a contemporary writer a monk called evagrius with some people it began in the head made the eyes bloody and the face swollen descended to the throat and then removed them from mankind with others there was a flowing of the bowels [Music] ivagrius was describing a massive outbreak of bubonic plague the first time it was recorded in history but how could the plague have anything to do with the climatic catastrophe unleashed seven years before plague is a bacteria a bacillus transmitted from infected rats to humans the carrier is the humble flea which feeds on rat's blood this is a flea which has had a blood meal and there's no plague organisms in its gut and you can see that it's quite stomach's quite full and everything's fine if we look at if we contrast this with a flea which has taken up some of the bacillus we can see that the there's a blockage here and this is brought about by a reaction between the bacillus and the fleas gap now the result of this is because the flea can't feed properly and they become so ravenously hungry because they they begin to starve in effect they the more they eat um well they can eat and eat and eat and they don't satisfy their hunger because their gut is blocked and so they will jump onto absolutely anything in the chance of getting a free meal [Music] as the rats themselves die from the plague the flea has an obvious new target to bite for blood humans and then as evagrius describes the agony begins some came out in swords which gave rise to great fevers and they would die two or three days later with their minds in the same state as those who had suffered nothing and with their bodies still robust others lost their senses before dying what keys found out is that scientists now know that outbreaks of plague are strongly related to changes in climate [Music] the sort of changes that followed 535 in particular cooling could have had a huge impact on the spread of the disease temperature directly affects how the plague bacteria form in the fleas gut well plague epidemics are temperature related what happens is that in the in the gut of the flea the the fibrin clots only forms at temperatures below 25 degrees centigrade above 25 degrees centigrade the clot doesn't form and any bacillus is simply passed out of the flea with the faeces if cooler conditions bring about the onset of the disease did that happen in 535ad if so where well according to one of our contemporary sources the church historian ivagrius the plague originated in ethiopia what we know both scientifically and historically is that the great lakes area of central africa is one of the oldest folky of plague activities uh in the world and that it would appear that the assertion of ivagrius is correct because africa is normally hot the disease is kept at bay but if africa was affected by the global cooling of 535 and 536 it would have been a lethal breeding ground for plague from africa via the trade routes ships rats and sailors could easily bring the plague up the coast first hitting the major port of alexandria in egypt and on into the heart of the roman empire and roman greed for one precious commodity from african elephants would only accelerate that process in the sixth century there was an enormous trade in african ivory hundreds of tons of ivory are being brought into the empire every year and being processed for luxury furniture for luxury objects which important magistrates would give out his gifts processed for diplomatic gifts that the empire could then use to impress his neighbours further to the north and further to the west people who would never have seen an elephant in their lives and it was essentially the european and mediterranean greed for ivory that brought the roof in only seven years after the climatic catastrophe in 542 a.d on the back of the ivory trade the plague surged into constantinople its impact was devastating they had to dispose of over 10 000 bodies a day week after week after week throwing them into the sea of special boats sticking them in the towers of the city wall filling up systems digging up orchards soldiers were forced to dig mass graves in which to cast the bodies of those who had died the impression is one of chaos and pandemonium constantinople europe's biggest city stank for month after month after month one contemporary writer recorded that when the number of dead reached a quarter of a million city officials simply stopped counting as people left the stricken city they took the plague to towns villages and farms throughout the empire untold millions died [Music] and unknown to the empire a second mortal threat was brewing 3 000 miles to the east [Music] the climatic catastrophe was also having an extraordinary effect on an extraordinary people they too would play their part in the decline of the roman empire and the simple reason for this new threat was the difference between the digestive systems of horses and cows [Music] in the isolated plains of mongolia hundreds of miles north of china something strange was about to happen before 535 a.d the overlords of the region were a tribe of violent barbarian horsemen the of ours chinese writers recorded their uncivilized way of life these are foul smelling barbarians from their point of view with outrageous habits the avars never bathed never washed their clothing they cleaned their dishes by having the women lick them dry all of which was simply horrifying to the chinese but in one respect as both chinese chronicles and archaeological finds show the others were years ahead of the competition [Music] fines from archaeological digs all over of our territories suggest that they were the most advanced horsemen in the world their style of riding saddles and mouth bits are still in use by hungarian planesmen today and many believe that the avars almost certainly invented the stirrup it was this large concentration of horses that gave them a military edge the latest in the military technology of that era the horses also provided food and sustenance the avars drank fermented mare's milk an alcoholic beverage horses were central to their existence but then in 535 and 536 the years of the catastrophe chinese records and tree ring evidence from siberia suggest that the mongolian step was crippled by cold and dry conditions the knock-on effect would have been long-term lasting decades [Applause] by 552 a.d the avars were attacked by a people who lived in the surrounding highlands the turks they had previously been ruled by the avars mysteriously the once invincible of our horsemen were crushed up until now the cause of this sudden reversal of power has never been explained but then david keyes had an idea [Music] so i was very puzzled by this and decided to try to try and find out what the mechanism was i thought well maybe it's something to do with their economy well the avar economy was a horse-based one the turk economy was a much more mixed one involving considerable numbers of cattle the question came to my mind well was there something about the way that a cattle economy works and a horse economy works the difference between those that might shed some light on the political events on the demise of the avars keys contacted john milne at macaulay land use center in aberdeen milne has made a detailed study of how different animals feed and survive yes these horses here are actually highland ponies but in terms of the sort of size uh they're very similar to what i believe the other horses would have been like they're quite similar to some of the at least in terms of size in terms of the mongolian and and kazakh horses that you that you see now milne had done intriguing research into the difference between horse dung and cow dung here you can see some horse dung and you can see that the it's very fibrous which demonstrates and it is made up of fairly large pieces of fiber which demonstrates that this has not been well digested by by the horse now if you compared some cattle pieces you would see that it was much more finely ground up uh and in fact much better digested than horse manure could the contrast in horses and cows digestive systems have made a vital strategic difference on the mongolian steps when after the catastrophe grass and vegetation were in a terrible state cows have a greater efficiency to digest food they also the ability to eat a wider range of different herbage types so they can eat for example very rank vegetation in contrast the horses are less capable of eating rank really poor quality vegetation than cattle and in a drought situation you get you would get eventually to the state where the horse was not able to eat enough food and because it was not been able to digest it successfully then it would not be able to survive and so in those consequent circumstances then the avars would be very vulnerable [Applause] i was absolutely amazed when when i found that in fact it was merely the differences between a a cows and a horse's stomach design that had probably had such a major effect on subsequent history chinese chronicles record how in the defeat by the once subject turks thousands of avars were slaughtered or enslaved their leader committed suicide most of the surviving of ours began a 4 000 mile trek westwards their journey triggered according to david keyes by the catastrophe was about to have a huge effect on history the avar refugee caravan cut across what is now northern kazakhstan skirting the northern shores of the caspian sea and on into the fertile grasslands to the south of the carpathian mountains an area which is now the balkans [Music] and as they traveled the avars recovered their horse technology was still superior to anything they found on their route once again the avars became a conquering people driving all others before them until finally roman writers recall how they reached the fringes of the roman empire they arrive in the late 550s as refugees within a decade their ruthless horsemanship ruthless military ability has come to dominate all the tribes all the groups of slavs huns germans living north of the danube on the empire's frontiers and having imposed their control over these groups the alvars can then turn their attention against the empire the roman empire already weakened by the plague was constantly harassed by avar incursions at one point constantinople was besieged by the barbarians rather than take over the avars opted for blackmail and extracted vast amounts of gold from the empire in return for not fighting some of it can be seen today in museums much of it is still believed to lie buried in the plains of hungary it's reckoned that over 50 years the avars netted in today's term seven billion pounds worth of gold from the roman empire [Music] the avar impact combined with the plague and the economic problems that ensued destabilized the empire and at the end of the day it can all be traced back to this climatic destabilization of the mid 6th century which was triggered by the volcanic eruption [Music] david keys believed a pattern was emerging which showed huge political consequences stemming from the catastrophe he had already found evidence of the catastrophe's effects throughout europe and the east now he turned to the americas where he found another extraordinary coincidence of timing and another historical puzzle where a great city had been destroyed but no one had ever known why [Music] in the early 6th century 125 000 people lived in teotihuacan in the central mexican plain in 500 a.d when the city reached its peak it really was what is called a primate city by that i mean the second next largest city is so far below it in size that there really you could almost say there are no other cities i mean that's an overstatement obviously but there were cities of 10 000 people 20 000. but compared to the 125 000 here that was nothing so it was the only huge large city in the entire central mexican plateau then midway through the sixth century shortly after the 535 a.d catastrophe things began to go wrong in teotihuacan [Music] for the past 20 years rebecca's story has been painstakingly studying skeletons of people who lived in one of the city's suburbs called kahinga the bones provide a remarkable history of the population's health [Music] well the clahinga population has adults it also has quite a few children and an awful lot of babies rebecca story began to notice that in teotihuacan's later period the population in particular the babies suffered a severe decline in health these kinds of infections that show up on the bone are long-lasting bacterial infections and they're very common on the children now babies shouldn't have infections like this normally they should be born with relatively good immunological protection from their parents their mother but in the case of clahinga we find lots of babies with already infectious reactions indicating that the health of the mothers was so poor that the children are getting sick as well the problem with the the very late population around the sixth century is that overwhelmingly it is babies children and individuals under the age of 25 they should not be dying at that proportion so they start to become 70 percent of my sample rather than the much lower 40 or 45 percent that they were in the earlier period [Music] it is a population that is in great trouble and is probably collapsing new scientific evidence suggests that the city's decline occurred around the middle to late 6th century 150 years earlier than previously thought for david keyes this re-dating was a breakthrough now in fact one can see that uh teotihuacan's fall um really comes straight on the heels of the climatic disaster and i think there's a very very high chance the two are are connected there are no existing tree rings or other evidence from mexico itself to show whether there was a significant climate change however lake deposits in the nearby yucatan peninsula show a 30-year long drought starting in the mid 6th century tree ring evidence from chile in california shows a dramatic reduction in tree growth from the late 530s onwards and a study of river levels in colombia shows that the mid to late 6th century was the driest period in the last three thousand years the evidence throughout the americas combined with rebecca storey's findings of malnutrition suggests that teotihuacan was gripped by a long lasting drought a drought which according to david keys's theory was directly linked to the climatic catastrophe and had a devastating effect on the city's supply of food when something happens to the food supply well that makes people more subject to getting ill because they're not getting enough food then this is a very dry environment water had to always have to been a very important thing and without water you have great sanitation problems sanitation would then lead to lots of diseases circulating through other people and causing mortality and they'll help and that affects the productivity of a city city's not productive when it's people are sick and that becomes one of the things that then say well no we don't want to go to teotihuacan anymore because it's not a good place to be according to the latest research teotihuacan was finally destroyed when the people rose up against their leader smashing their palaces and setting light to the city's biggest temple somebody went in there and set fired all the roof beams and caused the ceiling and roof to collapse bring down the upper walls and form a big mound of debris and that's what happened all up and down the main street of the city maybe they decided that elite class that was making demands on them was asking too much that the priests were supposedly bringing the rain and making the springs flow were no longer successful because the because the spring flow was dropping and the rains were diminishing then they lost confidence maybe in the priestly class as well what appears to happen is that you've got a destabilization um perhaps some religious and political changes followed by a revolution of some sort and the collapse of the city in a way similar to events in in europe indeed in the way that constantinople the roman empire was affected [Music] 535 um disturbs the status quo and allows history to reform itself all over the world it really is the interface between the ancient world and the world we live in today [Music] in central mexico it took 300 years for a new civilization to establish itself throughout the 6th century a similar story was unfolding all over the planet [Music] ancient civilizations crumbling others just beginning and according to david keyes one example of an emerging nation was england itself britain in the mid 6th century the dark ages the romans had left 100 years earlier in the west of the island native british tribes the celts fought to stem the tide of anglo-saxon invasion from northern europe according to legend it was the time of the death of king arthur his country turned into a wasteland as he rode dust through the land he found trees down and grain destroyed and all things laid waste as if lightning had struck in each place he found half the people in the villages dead [Music] the earth no longer produced when cultivated from that time on no wheat or other grain grew there and no tree bore fruit and very few fish were found in the sea for this reason the two kingdoms were called the wasteland but could the wasteland of legend be a distant memory of a climatic catastrophe that really did hit the native british as a result of 535 what is certain from british and irish animals is that the bubonic plague which had devastated the roman empire finally reached britain by around 547 a.d it entered mainly through ports on the cornish coast from which the british still traded with the roman empire this was a significant event in the history of western britain and ireland certainly as one goes through the animals one can find many references to plagues one of them is referred to as the mortalitus magna the great mortality another one is the mortalitas prima the first plague like this this does suggest something special they'd never experienced the plague before it was completely new horror that they knew nothing about they wouldn't have understood even what was happening suddenly people began to develop these terrible pustules underneath their armpits in their groins and they would have died in the most terrible agony according to keys the plague changed the political shape of britain at this time britain was divided in two in the west lived the native celtic britons the east was occupied by invaders from europe the angles and saxons east and west had very little contact with each other the celtic britons traded with the roman world the anglo-saxon peoples traded mainly with their former homelands of germany and scandinavia it meant that the celts the native britons were far more exposed to the plague arriving from the roman empire so by the time you come into the latter part of the century the celtic west and center have been have experienced a huge population reduction there's a population vacuum and so anglo-saxon peoples are able to move from the east they're able to move west into partially empty lands and uh england was was born keys theory is that england came about because the anglo-saxons were able to defeat the plague-stricken britons a 6th century poem tells of the defeat of one group of celts the men of gadothan and their leader madoff he did not retreat from battle until blood flowed like rushes he cut down men who did not flee the men of gaddafin relate on the floor of the hall but before madok's tent when he returned there would come but one from a hundred neither one can see 535 as a watershed where you see the the forces coming into play which create such countries as england spain france japan the united china now came the final and boldest turn in his theory could it be that the catastrophe was linked not just to the emergence of new nations but also to the birth of a new world religion islam [Music] this is all that is left today of the marib dam in yemen at the southern tip of arabia but at the beginning of the sixth century yemen was the region's greatest power it depended on the marib dam its greatest piece of engineering the marib was huge two thousand feet long feeding into hundreds of miles of canals but within a few years of the 535 catastrophe climatic chaos hit yemen first drought and then a succession of storms and flash floods which weakened the dam the constant attempts to repair the dam are recorded on contemporary inscriptions what we're looking at is one of the great inscriptions that was put up on the facade of the dam really commemorating the rebuilding in this of of the damn repair of the dam in this case in the year 542 and it's it's a long inscription describing all the various people who came and contributed to this and we can pick out right in the center here the cartouche the symbol of the ruler of the kingdom at that stage one abraha and there are a whole series of these inscriptions for about two or three hundred years and then they stop which is very indicative of exactly what the arabic sources are telling us that there was a period when this dam was broken and was not repaired again the marib dam was abandoned its ruin was also the ruin of yemen its population migrated to a new regional power base which emerged in its place around medina and mecca [Music] in 570 a.d the prophet muhammad was born in mecca it's in precisely that mecca medina area that muhammad was based and so it's really the growth of medina as a important political center that is so crucial in the early development of islam the climatic chaos had not only smashed the marib dam and shifted power to medina it also brought muhammad's own family to prominence the prophet's family or the prophet's ancestors had taken it upon themselves really to provide food to import food into this area and provide food for the population and this was one of their claims to to fame and to status muhammad's family's reputation for social concern helped his ministry take root in a time of drought famine and the plague which had spread from the roman empire [Music] i think muhammad's message was attractive because this was a period of upheaval and disturbance one's got this whole apocalyptic atmosphere in the ancient world at that time there's been war there's been a revolution the roman empire which had really dominated the political scene for what 800 years appeared to be tottering [Music] there is a lot of apocalyptic literature from this period there are a lot of people saying this is terrible the world's coming to an end how do we interpret these disasters what are they a sign of and so on the political certainties of the world were collapsing around everybody's ears nobody seemed sure of the future it was a very very unsettled time to live all these things can be traced back to an extent to the climatic chaos caused by the eruption of 535 and they all feed into the early evolution of islam [Music] [Music] [Music] now if a volcanic eruption 535 could wreak all this havoc and draw the ancient world to a final close and really help lay the foundations of the world we live in today what would happen if there was another massive eruption this is not fantasy or wild speculation while nothing may happen in the next hundred years there are a handful of underground volcanic monsters whose arrival date is long overdue the granddaddy of a mall is believed to be yellowstone caldera in wyoming this caldera is maybe twice the size of any known modern caldera and its eruptions which have occurred not once not twice but three times over the last two million years indicate that it can has devastated northern america several times besides long valley caldera there's a caldera in california which is also heating up uh the ground is shaking there there's been a die off of the forest by noxious gases carbon dioxide coming out of the earth public is very concerned about that volcano [Music] closer to home for some people would be the area around naples italy sure it's famous for vesuvius which has erupted many times in the past and potentially will again in the future there's also a caldera just on the north side of naples underlying a metropolitan area of campy flagray and potsoli where thousands of people live and have lived for a long time the last eruption in the campy flagra complex was in 1538 at that time three thousand people were killed by the immediate explosion now four hundred thousand people live within the same area the whole complex is still active and capable of major eruptions that would be a total disaster for italy a major disaster for europe and would no doubt have worldwide climatic repercussions which would have huge implications for agriculture huge implications from a disease point of view worldwide and would no doubt have the effect of destabilizing all sorts of potentially unstable countries all over the world [Music] it would change our climate it would produce a change in the pattern of wet and dry cycles for vast portions of the earth we're familiar with the el nino and la nina effects this would be even a much greater perturbation uh perhaps lowering the temperature of the global average temperature several degrees or more the biggest effect for for people anywhere is that it's going to disrupt their the food supply and it's going to take years to for the climate to either go back to normal or for people to change the the crops that they use and and the way that they plant them there may not be food to import from other countries because they'll need it every bit as much or more than than we will and if our agriculture has failed in some way then there just wouldn't be enough to eat i mean that's that to me seems to be the logic of the situation now in times past your right subsistence economies if they had low population densities they could go to the seashore and live on shellfish and indeed people sometimes did that under really stressful conditions but you can't do that nowadays there aren't enough shellfish to go around if we're confronted with a global event at any time in the future it's not quite clear how we would cope the whole infrastructure of civilization will collapse around us due to the huge environmental catastrophe that that would happen because of the failing of crop production the darkening of the skies communications would be taken out satellite communication aircraft transport would be interrupted very severely for a long period that type of event will occur in in the future well people start to struggle for resources i mean basically that means warfare in the modern world it's not quite clear exactly what would happen you either sit and starve or you get out there and try and acquire food and there's not much alternative in a really stressful situation one of the big lessons from 535 i think is that we're not talking about a big bang and then the world changes we're talking about a big bang and then it takes 100 to 150 years for the new reality to actually emerge [Music] what would happen in the future of course one doesn't know but i think that historians economists politicians should really pay rather more attention perhaps to the ability of natural forces to change history than they do at the moment

Channel: Chronicle - Medieval History Documentaries

Views: 1,155,423

Keywords: history documentary, medieval history documentary, middle ages, medieval history, the middle ages, 536 ad worst year in history, 536 ad documentary, 536 ad volcanic eruption, 536 ad worst year in history🥶😨, worst year in history, worst year in history 536, dark ages documentary, when was the worst year, worst year, climate history, dark ages history, medieval disaster, worst years to be alive in history, dark ages life, what was life like, medieval, weird history, chronicle

Id: Ax2x0MG-0Qo

Length: 98min 43sec (5923 seconds)

Published: Sat May 28 2022