Mike BaillieProfessor Emeritus

School 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

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End dates

Start dates

Date AD

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In Hollstein’s German work we see the same building pause after 1347+

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

Looking at European oak as a whole we see a downturn 1320-1350

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Date AD

Mea

n r

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Average of 13 oak chronologies

Grudd’s Swedish pines record temperature. Here they are compared with the oak record. Note that everything is

below normal 1325-1355

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Temperature

Oak growth

Date AD

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Reduced temperatureand oak growth

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

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Euro oak/temp

NZ cedar

Date AD

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Reduced temperatureand tree growth

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

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mean oldworld

mean new world

average

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0)

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

1410139013701350133013101290127012501250500

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Pearson datesStuiver dates

Date AD

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curve dropping steeply= enrichment

curveclimbing = depletion

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.

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New Zealand cedar

B. Isles oak

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

Here is what they observed

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Carbon dioxide in polar iceafter Siegenthaler et al. 1988

Date AD

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2 c

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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

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Changein numberof dates

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

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Tre

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USA reduced growth

Chinese famines

Mediterranean famines

Irish "failure of bread"

Anomalous eclipses

Dry fog

Justinian plague

China "stars not seen"

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

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Number of dendro-dated sites Southwest USA

Date AD

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Zero sites in AD 540s

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felling dates

estimated felling dates

Irish sites dated by dendrochronology (2005)

fellings

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Change of slopeAD 540s

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

It flattened some 2000 SQ Km of forest

This is pretty well what happened:a circa-15 megaton airburst

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)

GISP2 ICE Core Data Taylor, K.C., P.A. Mayewski, M.S. Twickler, and S.I. Whitlow. 1996

depth top depth bottom ammonia chlorine nitrate sulphate date top date bottom

32.9311 32.9626 2.19 41.83 75.01 94.85 40.33 40.41 1909.67 1909.59

32.9626 32.9941 1.66 28.85 55.04 67.52 40.41 40.5 1909.59 1909.5

32.9941 33.0256 1.17 14.89 43.8 51.12 40.5 40.58 1909.5 1909.42

33.0256 33.0571 1.4 4.15 43.12 28.37 40.58 40.67 1909.42 1909.33

33.0572 33.0887 3.09 77.88 25.13 154.01 40.67 40.75 1909.33 1909.25

33.0887 33.1202 7.16 8.03 102.64 36.09 40.75 40.84 1909.25 1909.16

33.1202 33.1517 2.65 5.95 109.45 27.13 40.84 40.92 1909.16 1909.08

33.1517 33.1832 11.16 14.27 104.64 102.51 40.92 41.01 1909.08 1908.99

33.1832 33.2147 2.17 11.97 85.37 62.16 41.01 41.09 1908.99 1908.91

33.2146 33.2461 2.08 13.71 71.46 81.07 41.09 41.18 1908.91 1908.82

33.2461 33.2776 1.96 14.48 62.91 69.47 41.18 41.26 1908.82 1908.74

33.2775 33.309 2.17 6.59 52.45 34.44 41.26 41.35 1908.74 1908.65

33.309 33.3405 16.68 10.35 44.99 22.71 41.35 41.43 1908.65 1908.57

33.3404 33.3719 542.3 280.7 195.48 114.56 41.43 41.52 1908.57 1908.48

33.3719 33.4034 435.4 249.09 131.34 126.19 41.52 41.6 1908.48 1908.4

33.4033 33.4348 21.88 109.75 44.94 135.87 41.6 41.69 1908.4 1908.31

33.4348 33.4663 6.57 12.68 104.96 102 41.69 41.77 1908.31 1908.23

33.4662 33.4976 5.87 11.9 102.05 62.06 41.77 41.86 1908.23 1908.14

39.499 39.5292 5.55 16.12 75.07 57.92 61.14 61.21 1888.86 1888.79

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’)

Year NGrip Crête GISP2 GRIP GISP DomeC Logicalcore core long core short minus 3 Summary

1342.50 years1342.751343.001343.251343.50 SO41343.75 SO41344.00 SO4 NH4 Acid Volcanic Acid1344.25 SO4 NH4 Acid Volcanic Acid1344.50 SO4 NH4 Acid Volcanic Acid Volcano1344.75 SO4 NH4 Acid Volcanic Acid1345.00 SO4 SO4 NH4 Acid Volcanic Acid1345.25 SO4 SO4 NH4 NH4+NO3 NH4+NO31345.50 SO4 NH4+NO3 NH4 NH4+NO3 NH4+NO31345.75 SO4 NH4+NO3 NH4 NH4+NO3 NH4+NO31346.00 SO4 NH4+NO3 NH4 NH4+NO3 NH4+NO3 Impact?1346.25 NH4+NO3 NH4 NH4+NO3 NH4+NO31346.50 NH4+NO3 NH4 NH4+NO3 NH4+NO31346.75 NH4+NO3 NH4 NH4+NO3 NH4+NO31347.00 NH4 NH4 NH4+NO3 Acid Kill NH4+NO31347.25 NH4 NH4 NH4 Acid Kill Ammonia1347.50 NH4 NH4 NH4 Acid Kill Ammonia1347.75 NH4 NH4 NH4 Acid Kill Ammonia Black Death1348.00 NH4+Acid Kill NH4 NH4 NH4 Acid Kill Ammonia Black Death1348.25 NH4+Acid Kill NH4 NH4 NH4 Acid Kill Ammonia Black Death1348.50 NH4+Acid Kill NH4 NH4 NH4 Acid Kill Ammonia Black Death1348.75 NH4+Acid Kill NH4 NH4 NH4 Acid Kill Ammonia Black Death1349.00 NH4+Acid Kill NH4 NH4 NH4 Acid Kill Ammonia Black Death1349.25 NH4 Black Death1349.50 NH4 Black Death1349.75 Black Death1350.00 NH4+Acid Kill Black Death1350.25 NH4+Acid Kill Black Death1350.50 NH4+Acid Kill Black Death

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

So, was there a big earthquake at the time of the Black Death?

Yes, there was ……on 25 January 1348

• And

• Some people at the time actually thought that “the plague was due to corruption of the atmosphere from the earthquake of St Paul’s Day (25 Jan) 1348”.

So, it could be suggested

• That it is not beyond the bounds of possibility

• That the tree ring downturn at the start of the Black Death may have involved an impact from space

• The only record of which is a huge ‘earthquake’ 25 Jan 1348

Obviously

• By now

• This presentation will be getting too strange for most people

• But can we match the madness?

How do you explain this:

• The German historian Hecker (1834) in discussing the weird things written around the time of the Black Death, mentions how at that time:

• a fiery meteor, which descended on the earth far in the East, had destroyed everything within a circumference of more than a hundred leagues, infecting the air far and wide ….

• A very good guess!

So

• There is a record of meteors c1350

• It is hardly likely that there would be any record of asteroids as the concept didn’t exist in the 14th century

• But is there any evidence for comets around the time of the Black Death?

Hughes points out the changes in frequency of comet observations

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Number of long-period cometsafter Hughes 2003

So, yes…

• After AD 500 more comets were recorded

• And

• After 1350 more comets were recorded

• Why would that be?

Could….

• It be either

• i) because there were more comets?

• Or

• ii) because people became more concerned about comets?

Are there specific references to comets at the time of the Black Death?

• Ziegler (1970) refers to a ‘Black Comet’ i.e. Comet Negra, seen before the ‘plague’

• Deaux (1969) says interestingly “The first records came out of the east …descriptions of the storms and earthquakes, of meteors and comets trailing noxious gases that killed trees and destroyed the fertility of the land”

• Where on earth did he get that from?

So…

• At the very least comets are mentioned, as is

• “a war between the sea and the sun in the Indian Ocean”

• Plus repeated references to

• “a noxious mist, contaminating all it touched”

Where does this leave bubonic plague?

• Well, Twigg and Cohn and Hoyle (and me) all questioned the conventional bubonic plague scenario. We didn’t like the rats/fleas idea.

• And we thought we were getting somewhere with alternative explanations until 2010.

Then in 2010

A paper was published showing that plague DNA has been located in numerous Black Death skeletons.

• See: Haensch S, Bianucci R, Signoli M, Rajerison M, Schultz M, et al. (2010) Distinct Clones of Yersinia pestis Caused the Black Death. PLoS Pathog 6(10): e1001134. doi:10.1371/journal.ppat.1001134

• Oops

However, I think the jury is still out

• On the issue of whether an extraterrestrial impact (or impacts) was part of the Black Death package.

• The tree-ring downturns have not gone away

• And the cause of those tree-ring downturns have to be explained whether or not the Black Death was bubonic plague.

It needs to be remembered

• That the environmental effects recorded in the tree rings may be telling us that the Black Death pathogen was caused to spread by underlying environmental conditions.

• It beholds the scientific community to fully understand what the fundamental causes may have been.

The Author

• Would like to thank all those who have generously made data available to allow a serious attempt to be made to understand the important global environmental events that took place between AD 1290 and 1400. Events which probably resulted in the deaths of one third of the human population of planet Earth.