in Natural and Fossil Fuel CO2
People want to be sure their emissions are not building up
time bombs for the future. The quantities of all three carbon
isotopes can yield evidence about the proportion of manmade
CO2 and natural CO2. I suspect that the manmade CO2 hardly
enters into the equation, but as a newcomer I still find this
science difficult to be sure I have grasped, and I've heard
competent scientists hold different opinions. I have a lot
of respect for Segalstad and Glassman - but they may be wrong
and as yet it is beyond my capacity to be sure.
10. The breakdown of the dogma - carbon isotopes
Suess (1955) estimated for 1953, based on the carbon-14
"Suess Effect" (dilution of the atmospheric CO2
with CO2 from burning of fossil fuel, void of carbon-14),
"that the worldwide contamination of the Earth's atmosphere
with artificial CO2 probably amounts to less than 1 percent".
Revelle & Suess (1957) calculated on
the basis of new carbon-14 data that the amount of atmospheric
"CO2 derived from industrial fuel
combustion" would be 1.73% for an atmospheric CO2 lifetime
of 7 years, and 1.2% for a CO2 lifetime of 5 years.
This is in conflict with IPCC researchers,
who assume that 21% of our present-day
(as of December 1988) atmospheric CO2, the assumed
rise in CO2 level since the industrial revolution, has been
contributed from Man's burning of fossil fuel (Houghton et
This large contradiction between the carbon-14 measurements
and the dogma, has worried many researchers. In order to make
Suess' measurements fit the dogma, it would be necessary to
mix the atmospheric fossil-fuel CO2 with CO2 from a different
carbon reservoir five times larger than the atmosphere alone
(Broecker et al., 1979). It was alternatively proposed that
the carbon-14-labelled CO2 would act completely differently
than the "ordinary" CO2: "However, the system's
responses are not the same for the CO2 concentration and for
isotopic ratios" (Oeschger & Siegenthaler, 1978).
The explanation is given that the CO2 levels will be governed
by the constructed evasion "buffer" correction factor,
while on the other hand (strangely enough) the isotope ratios
of the atoms in the very same CO2 molecules would be unaffected
by the evasion "buffer" factor, and further: "would
be equal in both reservoirs [the atmosphere and the ocean's
mixed layer] at equilibrium. This explains why the relative
atmospheric CO2 increase is larger than the Suess effect"
(Oeschger & Siegenthaler, 1978). This cannot be accepted,
when all chemical and isotopic experiments indicate that equilibrium
between CO2 and water is obtained within a few hours (see
Section 5 above).
Ratios between the carbon-13 and carbon-12 stable isotopes
are commonly expressed in permil by a so-called delta-13-C
notation being the standard-normalized difference from the
standard, multiplied by 1000. The international standard for
stable carbon isotopes is the Pee Dee Belemnite (PDB) calcium
CO2 from combustion of fossil fuel
and from biospheric materials have delta-13-C values near
"Natural" CO2 has delta-13-C values
of -7 permil in equilibrium with
CO2 dissolved in the hydrosphere and in marine calcium carbonate.
Mixing these two atmospheric CO2 components:
IPCC's 21% CO2 from fossil fuel burning + 79% "natural"
CO2 should give a delta-13-C of the present atmospheric CO2
of approximately -11 permil,
calculated by isotopic mass balance (Segalstad, 1992; 1996).
This atmospheric CO2 delta-13-C mixing value of
-11 permil to be expected from IPCC's model is
not found in actual measurements. Keeling et al.
(1989) reported a measured atmospheric delta-13-C value of
-7.489 permil in December 1978, decreasing to -7.807 permil
in December 1988 (the significance of all their digits not
justified). These values are close to the value of the natural
atmospheric CO2 reservoir, far from the delta-13-C value of
-11 permil expected from the IPCC model.
From the measured delta-13-C values in atmospheric CO2
we can by isotopic mass balance also calculate that the amount
of fossil-fuel CO2 in the atmosphere is equal to or less than
4%, supporting the carbon-14 "Suess Effect" evidence.
Hence the IPCC model is neither supported by radioactive
nor stable carbon isotope evidence (Segalstad, 1992;
To explain this apparent contradiction versus the IPCC
model, the observed delta-13-C value of atmospheric CO2 "must
be affected by other heavier [i.e. with high delta-13-C values]
carbon sources, such as is derived from the air-sea exchange
process" (Inoue & Sugimura, 1985). One way to make
this happen, would be if the isotopic exchange from air to
sea were different from the isotopic exchange from sea to
air; i.e. a gross non-equilibrium situation would be required.
Siegenthaler & Münnich (1981) were able to construct
such a simple theoretical kinetic, non-equilibrium model:
"Diffusion of CO2 into the water, which is rate limiting
for mean oceanic conditions, fractionates the carbon isotopes
only little. 13-C/12-C fractionations are found to be -1.8
to -2.3 permil for atmosphere-to-ocean transfer, and -9.7
to -10.2 permil for ocean-to-atmosphere transfer."
Inoue & Sugimura (1985) attempted to verify these
kinetic isotope fractionations experimentally at three temperatures:
288.2; 296.2; and 303.2 Kelvin, versus their equilibrium values
of -8.78; -7.86; and -7.10 permil, respectively, all with
uncertainty given as +/- 0.05 permil. Their reported air to
sea fractionations at these temperatures were -2 +/- 3; -4
+/- 5; and -5 +/- 7 permil, respectively. Their sea to air
fractionations were found to be -10 +/- 4; -13 +/- 6; and
-12 +/- 7 permil, respectively. (Reported alpha fractionation
factors and uncertainties have here been recalculated to alpha
minus one, multiplied by 1000, to get comparable fractionation
values). They conclude that the agreement is fairly good with
the theoretically deduced values of Siegenthaler & Münnich
(1981). Looking at the reported uncertainties,
however, the experimental data cannot be grouped in three
populations: their air-to-sea and sea-to-air data are not
significantly different from their reported air/sea/air equilibrium
value at the three different temperatures. Hence the
experimental data cannot be used as evidence for the proposed
theoretical difference in isotopic fractionation
for air/sea versus sea/air CO2 transfer due to differences
in kinetic isotope fractionation. I
cannot follow this paragraph for certain.
Siegenthaler & Oeschger (1987) touch in their carbon
cycle modelling, with carbon isotopes included, on the possibility
that the apparent atmospheric CO2 level increase is due to
marine degassing instead of accumulation of anthropogenic
CO2: "We will also discuss the sensitivity of the model
results to uncertainties in the ice core data, to different
model assumptions and to the (unlikely) possibility that the
non-fossil CO2 was not of biospheric, but rather of marine
origin." The word "unlikely" in parentheses
is indeed their wording. Their modelling shows ambiguously
that: "as expected, the results are similar to those
for the fossil-only input". But their modelling shows
a discrepancy with the ice core CO2 data, in addition to:
"it is somewhat surprising that observations and model
agree for 13-C but not for 14-C; this can, however, not be
discussed here any further". In their abstract, however,
they conclude on the contrary: "Calculated 13-C and 14-C
time histories agree well with the observed changes."
Humph, once again the conclusion
belies the evidence just explained!
The carbon cycle modelling of Siegenthaler & Oeschger
(1987) run into several problems making their models fit all
the data, leading them to write: "One possibility is
that the assumptions underlying our results are not fully
correct, i.e., that either the Siple ice core data deviate
from the true atmospheric concentration history or that the
carbon cycle models used do not yield the correct fluxes.
If we dismiss these possibilities, then other carbon sinks
than the ocean seem to exist." For the lack of validity
of the Siple ice core, see Section 4 above.
Based on this kind of modelling, IPCC states
as part of their "evidence that the contemporary carbon
dioxide increase is anthropogenic" (their Section 1.2.5;
Houghton, 1990): "Third, the observed isotopic
trends of 13-C and 14-C agree qualitatively with those expected
due to the CO2 emissions from fossil fuels and the biosphere,
and they are quantitatively consistent with the results from
carbon cycle modelling." Such
a correspondence is, however, not evident to the present author.
Segalstad (1992; 1993; 1996) concluded from
13-C/12-C isotope mass balance calculations, in accordance
with the 14-C data, that at least 96% of the current atmospheric
CO2 is isotopically indistinguishable from non-fossil-fuel
sources, i.e. natural marine and juvenile sources from the
Earth's interior. Hence, for the atmospheric CO2 budget, marine
equilibration and degassing, and juvenile degassing from e.g.
volcanic sources, must be much more important; and the sum
of burning of fossil-fuel and biogenic releases (4%) much
less important, than assumed (21% of atmospheric CO2) by the
authors of the IPCC model (Houghton et al., 1990).
The apparent annual atmospheric CO2 level increase,
postulated to be anthropogenic, would constitute only some
0.2% of the total annual amount of CO2 exchanged naturally
between the atmosphere and the ocean plus other natural sources
and sinks (Section 9 above). It is more probable that such
a small ripple in the annual natural flow of CO2 is caused
by natural fluctuations of geophysical processes. We have
no database for disproving this judgment (Trabalka, 1985).
Like Brewer (1983) says it: "Nature has vast
resources with which to fool us . . .".
Segalstad's mass balance calculations show that IPCC's
atmospheric CO2 lifetime of 50-200 years will make the atmosphere
too light (50% of its current CO2 mass) to fit its measured
13-C/12-C ratio. This proves why IPCC's wrong model creates
its artificial 50% "missing sink" (Segalstad, 1996).I
don't understand this paragraph either.
Updated 23rd October 2008