Mike Baillie
Professor Emeritus
School of Geography, Archaeology and Palaeoecology
Queen’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
60
Number of trees
Start dates
End dates
40
20
0
1 30 0
1 31 0
1 32 0
1 33 0
1 34 0
1 35 0
Date AD
1 36 0
1 37 0
1 38 0
1 39 0
1 40 0
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
200
Aver age of 13 oak chronol ogi es
Mean ring width (0.01 mm)
180
160
140
120
100
80
1290
1300
1310
1320
1330
1340
1350
Date AD
1360
1370
1380
1390
1400
Grudd’s Swedish pines record temperature. Here they are
compared with the oak record. Note that everything is
below normal 1325-1355
1 .2
170
Temperat ure
160
Reduced
temperature
and oak growth
0 .4
150
0 .0
140
-0 .4
130
-0 .8
120
Oak growth
-1 .2
1 29 0
110
1 31 0
1 33 0
1 35 0
Date AD
1 37 0
1 39 0
Smoothed oak growth
Fennoscandian temperature estimate
0 .8
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
1 50
120
Smoothed temp/oak growth
Reduced
temper atur e
and tr ee g rowth
100
1 30
90
1 20
80
Euro oak/temp
NZ cedar
1 10
1 29 0
70
1 31 0
1 33 0
1 35 0
Date AD
1 37 0
1 39 0
Smoothed NZ cedar growth
110
1 40
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
1 30
mean ol dwor ld
mean new wor ld
aver age
Ring-width values
(normalized to 100)
1 20
1 10
1 00
90
80
1 29 0
1 30 0
1 31 0
1 32 0
1 33 0
1 34 0
Date AD
1 35 0
1 36 0
1 37 0
1 38 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
8 00
Radiocarbon years BP
7 50
curve
climbi ng
= depletion
7 00
6 50
6 00
curve dr oppi ng
steepl y
= enri chment
5 50
Pearson dates
Stui ver dates
5 00
1 25 0
1 27 0
1 29 0
1 31 0
1 33 0
1 35 0
Date AD
1 37 0
1 39 0
1 41 0
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.
7 50
New Zeal and cedar
Radiocarbon age BP
7 00
6 50
6 00
B. Isles oak
5 50
1 28 0 1 29 0 1 30 0 1 31 0 1 32 0 1 33 0 1 34 0 1 35 0 1 36 0 1 37 0 1 38 0 1 39 0 1 40 0
Date AD
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
2 88
CO2 concentration (ppm)
2 86
2 84
2 82
2 80
Carbon dioxide in polar ice
after Siegenthaler et al. 1988
2 78
2 76
9 00
1 00 0
1 10 0
1 20 0
1 30 0
1 40 0
Date AD
1 50 0
1 60 0
1 70 0
1 80 0
1 90 0
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
80
Change
in number
of dates
60
40
20
0
1 30 0
1 32 0
1 34 0
Date AD
1 36 0
1 38 0
1 40 0
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
180
USA r educed g rowth
160
Chi na "stars not seen"
Tree-ring indices
Chi nese famines
140
Mediterr anean fami nes
Ir ish "fai lure of br ead"
120
Anomalous ecl ipses
Dry fog
100
80
Justinian plague
60
520
530
540
Date AD
550
560
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
Number of dendro-dated sites
Southwest USA
Number of sites per decade
20
Z er o sites
in AD 540s
10
0
2 00
2 50
3 00
3 50
4 00
4 50
5 00
5 50
6 00
6 50
7 00
7 50
8 00
7 50
8 00
Date AD
Irish sites dated by dendrochronology (2005)
60
f elling dat es
Cumulative number of sites
est imated f elling dates
40
Change of s lope
AD 540s
20
0
2 00
2 50
3 00
3 50
4 00
4 50
5 00
fellings
5 50
6 00
6 50
7 00
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
Whitlow. 1996
Taylor, K.C., P.A. Mayewski, M.S. Twickler, and S.I.
depth top
ammonia
depth bottom
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
1342.50
1342.75
1343.00
1343.25
1343.50
1343.75
1344.00
1344.25
1344.50
1344.75
1345.00
1345.25
1345.50
1345.75
1346.00
1346.25
1346.50
1346.75
1347.00
1347.25
1347.50
1347.75
1348.00
1348.25
1348.50
1348.75
1349.00
1349.25
1349.50
1349.75
1350.00
1350.25
1350.50
NGrip
core
Crête
core
SO4
SO4
SO4
SO4
SO4
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
NH4+Acid Kill
GISP2
long
SO4
SO4
SO4
SO4
SO4
SO4
SO4
SO4
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
GRIP GISP
core short
DomeC
minus 3
years
Logical
Summary
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
Acid
Acid
Acid
Acid
Acid
Volcanic Acid
Volcanic Acid
Volcanic Acid
Volcanic Acid
Volcanic Acid
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
Ammonia
Ammonia
Ammonia
Ammonia
Ammonia
Ammonia
Ammonia
Ammonia
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4+NO3
NH4
NH4
NH4
NH4
NH4
NH4
NH4
NH4
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Acid Kill
Volcano
Impact?
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
Black Death
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
6 00
Number of long-peri od comets
after Hughes 2003
Records of long-period comets
5 00
4 00
3 00
2 00
1 00
0
4 00
5 00
6 00
7 00
8 00
9 00 1 00 0 1 10 0 1 20 0 1 30 0 1 40 0 1 50 0 1 60 0 1 70 0
Date AD
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.