the "year without a summer" was not a year without a ring
DESCRIPTION
The Tambora eruption of 1815 cooled the planet and caused the "Year Without A Summer" in western Europe and eastern North America. But was it cold enough to cause trees across the Northern Hemisphere to skip a ring?TRANSCRIPT
The “Year Without a Summer” WAS NOT
a year without a ringSco! St. George
University of Minnesota
The 1815 eruption of Mount Tambora is estimated to be the largest volcanic event in recorded history.
Source: Wikipedia User Indon
Ashfall from the 1815 eruption extended more than 1,300 km away from Tambora.
Source: Desert Research Institute
Source: Dai et al, Journal of Geophysical Research, 1991
Sulfate aerosols emi!ed by Pinatubo
“ ”Atkins, 1887
History of Hawley
Severe frosts occurred [in Massachuse!s] every month; June 7th and 8th snow fell, and it was so cold that crops were cut down, even freezing the roots…
Source: D’Arrigo et al., Journal of Geophysical Research, 2013
Early 19th century temperature observations show 1-2°C cooling in central Europe and the eastern United States between AD 1815 and 1816.
1816THE “YEAR WITHOUT A SUMMER”
MODELS PROXIES-2°C -1°C
Michael Mann and colleagues used numerical simulations of climate and tree growth to show that when temperatures fall abruptly for one or two growing seasons, trees in these regions undergo li!le or no growth.
“ ”Nature Geoscience press release
February 2012
A.D. 1259 A.D. 1816
“ ”IF NO RING WAS FORMED IN A GIVEN YEAR, THAT CREATES A FURTHER COMPLICATION,
INTRODUCING AN ERROR IN THE CHRONOLOGY ESTABLISHED BY
COUNTING RINGS BACK IN TIME.
Dr. Michael Mann Penn State News, February 6, 2012
‘LOCALLY-ABSENT’ RING
The cambium of trees of many species may be locally dormant, in the sense that no new cells are produced, throughout one or more growing seasons.“ ”
Edmund Schulman Ecology, 1941
1809 1811 181218081807
Source: Sarah Appleton
?COULD
THE GLOBAL TREE-RING NETWORK CONTAIN
WIDESPREAD (BUT UNRECOGNIZED)
‘MISSING’ RINGS?
Large sets of ring-width data have provided the foundation for many proxy estimates of regional or global surface temperature.
Source: Intergovernmental Panel on Climate Change, AR5, Working Group 1
Source: Cook et al., Science, 2010
The Monsoon Asia Drought Atlas generated yearly maps of drought severity based on ring-width and other tree-ring measurements.
Source: Meko et al., Geophysical Research Le!ers, 2007
Surrogate estimates of discharge have been used to produce ‘worst-case’ scenarios for water supplies in major western rivers, including the Colorado.
±0
BEvidence against the ‘missing ring’ hypothesis
OTHER CHRONOLOGICAL
EVIDENCE
BOREAL TREES AND MISSING RINGS
EXTRATERRESTRIALCONFIRMATION
AThe Northern Hemisphere tree-ring network
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
Source: Phil Camill
Source: Uday Kunwar Thapa
Fri!s, H.C. Growth-rings of trees: their correlation with climate. Science 154, 973-975 (1966).
-0.8 -0.6 -0.4 -0.2 +0.2 +0.4 +0.6 +0.8
correlation coefficient (ring-width vs. local climate)
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
Source: Kevin Anchukaitis
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER TEMPERATURE
Source: St. George, Quaternary Science Reviews, 2014
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
?COULD
THE GLOBAL TREE-RING NETWORK CONTAIN
WIDESPREAD (BUT UNRECOGNIZED)
‘MISSING’ RINGS?
BEvidence against the ‘missing ring’ hypothesis
OTHER CHRONOLOGICAL
EVIDENCE
BOREAL TREES AND MISSING RINGS
EXTRATERRESTRIALCONFIRMATION
Adding an ‘absent ring’ to a tree-ring sequence causes the dates of all prior rings to be pushed back by one year.
Source: Alexandra Witze
1783THE LAKI (ICELAND) ERUPTION
Source: St. Thomas Productions
During several of the summer months of the year 1783, when the effect of the sun's rays to heat the earth in these northern regions should have been greater, there existed a constant fog over all Europe, and a great part of North America.
“ ”Benjamin Franklin
Memoirs of the Literary and Philosophical Society of Manchester, 1784
Across Alaska and northwestern Canada, trees formed wood much less dense than normal during the AD 1783 growing season.
Source: Jacoby et al., Quaternary Science Reviews, 1999
Reconstructed summer temperatures for Alaska (estimated from latewood density) was more than 4 s.d. below the long-term mean.
Source: Jacoby et al., Quaternary Science Reviews, 1999
Source: Briffa et al., The Holocene, 2002
IF 1816 IS MISSING
THEN 1783 ➜ 1782
Source: Esper et al., Dendrochronologia, 2013
Source: Esper et al., Dendrochronologia, 2013
If tree-ring records from Europe are shi$ed back one year, their strong correlation with long temperature records disappears.
OTHER CHRONOLOGICAL
EVIDENCE
BOREAL TREES AND MISSING RINGS
EXTRATERRESTRIALCONFIRMATION
Max Torbenson University of Arkansas
?HOW OFTEN DO TREES FORM
LOCALLY-ABSENT RINGS AND WHY?
1,063 RECORDS HAD AT LEAST ONE
ABSENT RING.
1,296 RECORDS DID NOT HAVE
A SINGLE ABSENT RING.
1259 1453
1783 1816
20% 40% 60% 80% 100%0%Intensity of locally-absent rings
1259 1453
1783 1816
20% 40% 60% 80% 100%0%Intensity of locally-absent rings
Source: St. George et al., Geophysical Research Le!ers, 2013
PiceaPinus
PseudotsugaQuercusLarix
a
c
# re
cord
s
% re
cord
s
b
18ºN
36ºN
54ºN
72ºN90ºN
120ºW 60ºW 0º 60ºE 120ºE 180ºW180ºW
1000 20001200 1400 1600 1800
2000
1000
0 0%
12%
6%
1000 20001200 1400 1600 1800Year Year
0º
How o$en have locally-absent rings occurred in the Northern Hemisphere tree ring-width network?
0% 2% 4% 6% 8%
20°N
40°N
60°N
80°N
Latit
ude
Percentage of locally-absent rings
0% 2% 4% 6% 8%
b
a
Picea Quercus
Pinus Pseudotsuga
Larix Other genera
1500
1000
500
0
# re
cord
s
Source: St. George et al., Geophysical Research Le!ers, 2013
PICEA LARIX(spruce) (larch)
Source: Phil Camill
134 881TREE-RING ‘YEARS’
ZERO CASESWHERE A GROWTH RING WAS MISSING FROM EVERY TREE AT THE SAME SITE.
MANY (OR MOST) TEMPERATURE-LIMITED FOREST STANDS
IN THE NORTHERN HEMISPHERE WOULD NEED TO SHOW A REACTION
TO THERMAL STRESS THAT HAS (ESSENTIALLY) NEVER BEEN OBSERVED
ANYWHERE.
OTHER CHRONOLOGICAL
EVIDENCE
BOREAL TREES AND MISSING RINGS
EXTRATERRESTRIALCONFIRMATION
Source: Miyake et al., Nature, 2012
The 14C content of Japanese cedar tree rings increased by 1.2% from AD 774 to 775.
We’d expect these [supernovae and superflares] to be global events that would appear in the radiocarbon of any long tree-ring chronology around the world.
“ ”Kevin Anchukaitis
National Geographic, June 7, 2011
Source: Büntgen et al., Nature Climate Change, 2014
Radiocarbon measurements of a subfossil pine (Pinus cembra) show the same 1.2% increase in 14C from AD 774 to 775.
ALL STUDIES DEMONSTRATE THE PRECISION
OF TREE-RING DATING BACK TO THE
YEAR 775.Büntgen et al., Nature Climate Change, 2014
“ ”
MODELS PROXIES-2°C -1°C
None of this is to say that there are not challenges associated with using tree ring proxies to identify and evaluate the timing and environmental consequences of volcanic eruptions.
“ ”D’Arrigo et al., 2013
Journal of Geophysical Research
?COULD
THE GLOBAL TREE-RING NETWORK CONTAIN
WIDESPREAD (BUT UNRECOGNIZED)
‘MISSING’ RINGS?
