Mike BaillieProfessor EmeritusSchool of Geography, Archaeology and PalaeoecologyQueen’s University Belfast Athens October 2011 Tree rings and plagues: some new observations
Chronologies are constructed by overlapping ring patterns back in time. These allow us to view tree responses at annual resolution.
The Great Plagues • It is widely asserted that there have been three great plagues, these were • 1) The Plague of Athens 430 BC • 2) The Justinian Plague AD 542 • 3) The Black Death AD 1348 • I’m going to consider just the last two
First, how did I get interested in the Black Death?I observed a depletion/regeneration in Irish oak at 1350.A lot of trees started regenerating after that date.
This was probably due • To the reduced human pressure on existing woodlands • Less people to work the woods • Less need for new buildings • Marginal land returning to forest • So we could ‘see’ the Black Death in the tree-ring record.
We see this very clearly in the start and end dates of Irish oaks. Up to 1350 equal numbers. After 1350 lots more start dates
Kuniholm found that the pause showed in Greece after 1348. For 70 years or more no new houses were needed
So European dendrochronologists noted the effects of the Black Death • Mostly due to difficulties in constructing chronologies or in pauses in the record of dated structures • However, there were other symptoms
Grudd’s Swedish pines record temperature. Here they are compared with the oak record. Note that everything is below normal 1325-1355
This evidence… • Suggested a bigger scale environmental downturn around the time of the Black Death • Temperature seems to have been involved • It was then discovered that there was reduced growth in Lemin’s New Zealand cedar chronology. Indicating a global component to the downturn.
Averaging the European oak/pine record and comparing with New Zealand cedar highlights the 14th century downturn
Making up N and S hemisphere mean chronologies shows coherent global signal, with downturns in the 1340s and in 1361; the year of the 2nd wave of the plague
All of this indicated • That the Black Death sits in a global tree-ring downturn • Obviously this isn’t in the history books • And, as noted, the 1361 downturn coincides with the second wave of pestilence.
So, what was going on? • It isn’t just tree-rings that show effects around 1350 • If we look at the radiocarbon calibration curve we see changes too • Remember that the calibration results are based on precisely-dated tree rings
Stuiver and Pearson’s radiocarbon calibration results. Note the change from enrichment to depletion after 1335
So… • Now we know that in the 1330-1350 period the amount of radiocarbon in the atmosphere goes from enrichment (dates getting rapidly younger) to depletion (dates getting older)….. as the radiocarbon in the atmosphere is DILUTED by inert carbon • i.e. something is putting old carbon into the atmosphere ….what? and how?
We can now look at this period in more detail using a replicated N and S hemisphere calibration. The move from 14-C enrichment to depletion is clearly there.
So, we’re interested in what may have caused this 14-C depletion • This is where a bit of serendipity helps • It so happens that people had measured CO2 in polar ice
If you combine the 14-C and the CO2 information • You can deduce… • That the increase in CO2 must be after 1335…..because… • It cannot have happened while 14-C is enriching, only while it is depleting
So….. • Around the time of the Black Death something really did pump a lot of inert carbon into the Earth’s atmosphere • The most likely source has to be the oceans • Possibly an ocean turnover event?
What…. • Could cause an ocean turnover? • Something tectonic? • Something extraterrestrial? • Let’s see what we can find.
On a different tack, SW-USA archaeological site construction slows down at exactly 1348/1350
Now… • This American observation is interesting because • Bubonic plague cannot have reached America • So anything showing in America at 1350 has to be either environmental or airborne
If we go back to the Justinian plague there is also a global tree-ring event there
This AD 536-545 downturn shows up • In tree ring chronologies from • Eurasia • Europe • North America • South America • A truly global environmental event • The following figure shows plots of the numbers of archaeological sites dated by dendrochronology in SW America and Ireland across AD 540. The American data is from Robinson and Cameron.
At 540 we see ‘change’ in both the New and Old Worlds, just as we saw at 1350
And here is the dilemma • If both 1350 and 540 show up in the Old World and in the Americas • Either both ‘plagues’ were environmentally driven • Or, the ‘agent’ was in the atmosphere
Once the issue of ‘something in the atmosphere’ is raised as a possibility. You can find some interesting statements. • Gibbon in Decline and Fall states that “the atmosphere was corrupted for an extended period of 52 years after 542” • and • Writers around the time of the Black Death repeatedly refer to the ‘atmosphere being corrupted’
Remember: right up to the present the conventional wisdom • Says that the Justinian plague and the Black Death were due to bubonic plague • Carried by fleas on rats • Anyone who didn’t know that might well be following up those hints that the agent may have been in the atmosphere!
If you are interested in non-conventional ideas. • You might want to know why Cassiodorus writing in 537 noted “something coming on us from the stars” • Or why Roger of Wendover noted: • AD 541 “a comet seen from Gaul so close that the whole sky seemed to be on fire and the same year real blood dropped from the sky and a dreadful mortality ensued” • Or why Gibbon thought the atmosphere was corrupted from 542-594
Or why Thorndike, writing in 1934. • Cites a late-fifteenth century abbot, Trithemius, reiterating information from Giovanni Villani who died in 1348: • “Trithemius further states, as Villani had at the time, that in 1347 (sic) a vast vapour from the north settled over the earth to the great terror of those who saw it, and that some writers mention that in this year innumerable minute forms of animal life (quasdam minutas bestiolas) fell from heaven to earth in the orient and produced the pest by their corruption”
Or why Arrizabalaga (1994) noted the following contemporary record • …Agramont (24 April 1348) said nothing concerning the term epidímia, but he extensively developed what he meant by pestilència. He gave this latter term a very peculiar etymology, in accordance with a form of knowledge established by Isidore of Seville (570-636) in his Etymologiae, which came to be widely accepted throughout Europe during the Middle Ages. He split the term pestilència up into three syllables, each having a particular meaning: pes (= tempesta: ‘storm’, ‘tempest’), te (= temps: ‘time’), and lència (= clardat: ‘brightness’, ‘light’); hence, he concluded, the pestilència was ‘the time of tempest caused by light from the stars’
i.e. pestilència • As of 24th April 1348, was: • ‘the time of tempest • caused • by • light from the stars’
Or why • Fred Hoyle and Chandra Wickramasinghe thought that the peculiar spread of the Black Death • “looked as if the ‘disease’ was dropping through the atmosphere” • All of these went against the rat/flea conventional wisdom
So I went against the conventional wisdom too. • I asked, based on all the foregoing – ocean turnover, tree ring downturn, American effects, strange statements etc • Could there have been an extraterrestrial component to the Black Death? • And to start we have to go to Tunguska
An object from space (possibly a fragment of Comet Encke) exploded over Siberia on 30 June 1908
The ice cores • Luckily, on the Web the American Ice core workers have put just enough chemistry that we can see what happened in the middle of 1908 • Note on the next illustration the chemistry at 1908 (highlighted in yellow)
So at the time of Tunguska • At AD 1908.48 you have a big spike of • Ammonium • Chlorine • Nitrate • Sulphate • Pretty definitely caused by the Tunguska impact of 30 June 1908
Just out of interest… • What is in the ice at the time of the Black Death? • Unfortunately there is no high resolution chemistry across 1340-1360 • But there is low resolution data
In the next illustration we see • Around roughly 1343-1345 evidence consistent with a volcano, i.e. SO4 • From around 1345 to around 1349 • There is ammonium and nitrate; sometimes ammonium is also hinted at by the reduction in background acid • (indicated as ‘acid kill’)
So • There is ammonium and nitrate in the ice cores at the time of the Black Death • Leaving open the question….did the 14th century tree ring downturn actually involve an extraterrestrial bombardment?
But, for a minute, let’s think about something else • In the whole of history, there has only been ONE earthquake known to have been caused by an impact from space. • That was the earthquake caused by the Tunguska airburst 30 June 1908 • EVERY OTHER EARTHQUAKE IN THE LAST 5000 YEARS WAS AN ‘EARTH’ QUAKE • Does that make any sense?
When you think about it • In history all earthquakes are Earth quakes • However, Tunguska, with an associated earthquake out to 900 km • Tells us that some historical ‘earthquakes’ might be the secondary effects of distant impacts