Davis, W.J. 2017.
The relationship
between atmospheric
carbon dioxide
concentration and
global temperature
for the last 425
million years.
Climate 5: 76;
doi: 10.3390/cli5040076.
NOTE:
Davis (2017) notes that
"a central question for
contemporary climate policy
is how much of the
observed global warming
is attributable
to the accumulation
of atmospheric CO2
and other trace
greenhouse gases
emitted by
human activities."
Climate alarmists
will claim "almost all."
Unbiased scientists
say: "No one knows".
SUMMARY:
Davis concludes
that his analysis
"demonstrates
that changes
in atmospheric
CO2 concentration
did not cause
temperature change
in the ancient climate,"
which findings,
he adds,
"corroborate the earlier
conclusion based on study
of the Paleozoic climate
that 'global climate may be
independent of variations
in atmospheric carbon
dioxide concentration"
( Came et al., 2007 ).
( see "Reference" at end of article )
The lack
of correlation
between CO2
and temperature
across the historical
record is obvious.
"More than 95%
of the variance
in temperature
is explained by
unidentified
variables
other than the
atmospheric
concentration
of CO2."
But even if there
was correlation,
"correlation does not
imply causality, but the
absence of correlation
proves conclusively
the absence of causality."
The big question is whether
425 million years of these
climate proxy data
... will change the minds
of any climate alarmists !
DETAILS:
Davis analyzed
the relationship
between
historic temperature
and atmospheric CO2
using the most
comprehensive
empirical databases
of these two variables
available for the
Phanerozoic period
( 522 to 0 million years
before present ).
6680 proxy
temperature and
831 proxy CO2
measurements
were used,
enabling what
Davis described as:
"the most accurate
quantitative empirical
evaluation to date of
the relationship between
atmospheric CO2
concentration
and temperature."
Multiple statistical
procedures,
and analyses,
were applied to
the proxy records,
and the resulting
relationship is in
the chart below.
The most striking
observation is the:
"apparent
dissociation
and even an
anti-phasic
relationship"
among the
two variables.
Davis reports that:
(1)
"a CO2 concentration
peak near 415 My,
occurs near
a temperature
rough at 445 My,"
(2)
"similarlly CO2
concentration peaks
around 285 Mybp
coincide with
a temperature trough
at about 280 My ,
and also with the
Permo-Carboniferous
glacial period
(labeled 2 in the Figure),"
(3)
"the atmospheric CO2
concentration peak
near 200 My
occurs during
a cooling climate,
as does another,
smaller CO2
concentration peak
at approximately 37 My,"
(4)
"the shorter
cooling periods
of the Phanerozoic,
labeled 1-10 in the Figure,
do not appear qualitatively,
at least, to bear
any definitive relationship
with fluctuations in the
atmospheric concentration
of CO2",
(5)
"regression of
linearly-detrended
temperature proxies,
against atmospheric CO2
concentration proxy data,
reveals a weak,
but discernible,
negative correlation
between
CO2 concentration
and temperature,"
and
(6)
"the percent of variance
in temperature that can
be explained by variance
in atmospheric CO2
concentration,
or conversely,
R2 × 100, is 3.6%,
[indicating that]
more than 95%
of the variance
in temperature
is explained
by unidentified
variables
other than the
atmospheric
concentration
of CO2."
Figure 1, below:
Temperature
( T, red line )
and atmospheric
carbon dioxide
( CO2, green line )
concentration
proxies during the
Phanerozoic Eon.
Glaciations based on
independent sedimentary
evidence are the vertical
blue cross-hatched areas,
while putative cool periods
are are the vertical
solid blue bars.
Major cooling and warming
cycles are shown by the
colored bars across the top
while geological periods
and evolutionary milestones
are shown across the bottom.
Abbreviations:
Silu, Silurian;
Neo, Neogene;
Quatern, Quaternary.
The three major
glacial periods
and 10 cooling periods,
that are identified by
blue cross-hatches
and solid blue lines,
respectively, are:
Glacial periods.
1. late Devonian/early
Carboniferous;
2. Permo-Carboniferous;
3. late Cenozoic.
Cooling periods.
1. late Pliensbachian;
2. Bathonian;
3. late Callovian
to mid-Oxfordian;
4. Tithonian to
early Berriasian;
5. Aptian;
6. mid-Cenomanian;
7. mid-Turonian;
8. Campanian
-Maastrichtian
boundary;
9. mid-Maastrichtian;
10. late-Maastrichtian.
10. late-Maastrichtian.
Reference:
Came, R.E., Eller, J.M.,
Veizer, J., Azmy, K.,
Brand, U. and Weldman, C.R.
2007
Coupling of surface temperatures
and atmospheric CO2 concentrations
during the Paleozoic era.
Nature 449: 198-201.