Putting the false UN IPCC 13C/12C isotope argument to bed forever

By Bud Bromley | September 23, 2022

Roy Spencer, PhD. (attached pdf.) and Murry Salby, PhD. (video link and text excerpt below), Tom Segalstad, PhD., (excerpts and links below and paper attached as pdf) and Edwin X Berry, PhD., (excerpt and link below and pdf attached) and Werner Stumm, PhD., have explained the problems with IPCC claimed carbon isotope “proof.”  Key excerpts and links to these works are presented here.  Brief bios of these scientists are below.

At this link is an excellent video lecture by Professor Murry Salby, PhD. The problem with the isotope “proof” is explained beginning at the 25-minute mark.

Professor Salby Video

The following is quoted from Professor Salby’s 2012 book, “The upward trend of CO2 is commonly ascribed to emission by human activities. Support for this interpretation comes from isotopes of carbon. Carbon 13, like carbon 12, is stable. It represents about 1% of the isotopic composition of CO2. However, its concentration varies between reservoirs of carbon. Vegetation and ancestral carbon, fossil fuel, are slightly leaner in 13C than is the atmosphere.” (6)

(6) Reflecting increased efficiency of photosynthesis with the lighter form of carbon.

“Proxy evidence of δ13C is more variable than that of rCO2 [atmospheric mixing ratio of CO2]. It also has little overlap with the more recent instrumental record (crosses). Nevertheless, reconstructed δ13C decreased over the last two centuries, mirroring the contemporaneous increase of rCO2.”

“The decrease of δ13C, together with the increase of rCO2, reflects the addition of CO2 that is 13C lean. This feature is consistent with the combustion of fossil fuel, as well as biomass destruction.  It is equally consistent, however, with the decomposition of organic matter derived from vegetation. Thus, associating the decrease of δ13C to the combustion of fossil fuel requires the exclusion of other sources that are 13C lean. In particular, it relies on CO2 emission from the ocean, which overshadows other sources of CO2 (Sec. 17.3), having the same isotopic composition as the atmosphere (which would then be left unchanged). Only then can the decrease of δ13C be isolated to continental sources, which are weaker and, in particular, to the combustion of fossil fuel, which is an order of magnitude weaker. Yet, the isotopic composition of marine organic matter is influenced by a variety of biological and environmental factors (Francois et al., 1993; Goericke et al., 1994). Through those factors, δ13C in the upper ocean varies significantly. Along with transport from the deep ocean, which is likewise uncertain, they leave the magnitude and composition of ocean emission poorly understood (Sec. 1.6.2).” ~ Salby, Murry. Physics of the Atmosphere and Climate, page 24. 2012. Cambridge University Press.  https://climatecite.com/physics-of-the-atmosphere-and-climate-pt-1/

Tom Segalstad, PhD. explains: “Carbon Isotopes and Mass Balance Calculations Stable 13C/12C isotope ratios, expressed as delta 13C vs. PDB, provide the only way to determine unequivocally the fraction of anthropogenic CO2 in the atmosphere. The natural atmospheric CO2 reservoir has delta 13C ~= -7‰ when in isotopic equilibrium with marine HCO3- (aq) and CaCO3 (s). CO2gas from burning of fossil-fuel and biogenic materials has delta 13C ~= -26‰ (Ohmoto and Rye, 1979; Deines,1980). IPCC identifies 280 ppmv (ppm by volume) as the preindustrial CO2 value, but that may be arbitrarily influenced by the selection of low-value CO2 data from ice cores (where measured values up to 7,400 ppmv were omitted), as well as from them is matching of contemporary measurements with different ages (Jaworowski et al., 1992a; 1992b).”

“IPCC claims the rise in CO2 to 353 ppmv in 1990, and 379 ppmv in 2005, is due only to anthropogenic CO2 (IPCC, 1990; 2007).The delta 13C value reported for atmospheric CO2 was-7.489‰ in December 1978, decreasing 10 years later to -7.807‰ in December 1988 (Keeling et al., 1989). If the resultant decrease were solely the product of mixing natural CO2 with CO2 produced from the burning of fossil fuels or plants (~79% / ~21% CO2mix; lifetime 50–200 years; IPCC, 1990), the current atmospheric CO2 delta 13C value should be -11, much lower than reported (Segalstad, 1992; 2008). The December 1988 atmospheric CO2 composition has been computed for its 748 Gt C (Gt =1015 g) total mass and delta 13C value of   -7.807‰ for three components: (1) natural fraction remaining from the preindustrial atmosphere, (2) cumulative fraction remaining from all annual fossil-fuel CO2 emissions, and (3) carbon isotope mass-balanced natural fraction. The masses of component (1) and (2) were computed for different atmospheric lifetimes of CO2 (Segalstad,1992).  The result fits a lifetime of about five years, in agreement with 14C studies (see Sundquist, 1985;Segalstad, 1998; 2009; for further references). The mass of all past fossil-fuel and biogenic emissions remaining in the current atmosphere was -30 Gt C or less; i.e. a maximum of around 4% of the total, corresponding to an atmospheric concentration of approximately 14 ppmv. The implication of the five-year lifetime is that approximately 135 Gt C (18%) of the atmospheric CO2 is dynamically exchanged each year (Segalstad, 1992; 1996; 1998; 2008).  The above calculations also demonstrate that over this 10-year period (1978–1988), at least 96% of the atmospheric CO2 is attributed to non-fossil-fuel sources, and this percentage has not likely varied much in the years since. Hence, it is clear marine degassing and juvenile degassing from sources such as volcanoes must be much more important for the atmospheric CO2 budget than the burning of fossil-fuels and biogenic materials. IPCC has failed to recognize this conclusion.” ~ Segalstad, Tom V., (17) (PDF) Some thoughts on ocean chemistry (Chapter Available from this link: [accessed Sep 23 2022].

A longer refutation of the IPCC’s isotope “proof” by Tom V. Segalstad is attached as pdf, which includes an extensive list of references.  Conclusion: “The atmospheric CO2 level is ultimately determined by geologic processes. The carbon on the Earth’s surface has come from CO2 degassing of the Earth’s interior, which has released about half of its estimated CO2 contents throughout Earth’s history during the 4,500 million years up to now (Holland, 1984). Important geologic processes are volcanism and erosion, releasing carbon from the lithosphere and the Earth’s interior to the atmosphere – ocean – biosphere system. These processes are counteracted by sedimentation of carbonate and organic carbon in the hydrosphere (mainly the ocean). The balance between these two main processes determines the CO2 level in the atmosphere (e.g., Kramer, 1965; McDuff & Morel, 1980; Walker & Drever, 1988; Holmén, 1992). “Thus, while seawater alkalinity is directly controlled by the formation of calcium carbonate as its major sedimentary sink, it is also controlled indirectly by carbonate metamorphism which buffers the CO2 content of the atmosphere” (McDuff 18 & Morel, 1980).” ~ Segalstad, Tom V., Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO2: on the construction of the “Greenhouse Effect Global Warming” dogma. Pdf attached.

A detailed discussion of the chemistry is presented in Aquatic chemistry : chemical equilibria and rates in natural waters, chapter 4.9 Carbon Isotopes and Isotope Fractionation, by Stumm, Werner. Publication date 1996.   https://archive.org/details/aquaticchemistry0000stum/page/194/mode/2up   pages 195-205.

Enrichment of the heavier, stable isotope 13CO2 is naturally occurring in the ocean.   The lighter isotope CO2 is preferentially vaporized out of the ocean surface into air.  “The distribution factor has been experimentally determined (Deuger & Degens, 1967).”  Enrichment of the heavier isotope CO2 in the ocean surface is “9.2% at 0 degrees C and 6.8% at 30 degrees C.  This fractionation occurs predominantly in the hydration stage and not during the passage of the atmospheric carbon dioxide through the air-water interface; that is, the reaction

13CO2(g) + 12CO2(aq) <-> 12CO2(g) + 13CO2(aq)

has an equilibrium constant of K = alpha = 1.0.”  (Stumm, W. 1996. page 200)

Dr. Stumm’s book provides this reference on this topic:  Sarmiento, J. L. (1993) Ocean Carbon Cycle: Most of the Carbon Released from Fossil Fuels Will End Up in the Oceans Where a Complex Cycle of Circulation and Other Processes Control Its Fate. Chem. Eng. News 72, No. 22 (May 31), 30-43.

Edwin V. Berry, PhD., summarizes problems with the IPCC model from a slightly different perspective in the abstract of his paper, which includes extensive references.  (Link below and attached as pdf): “The Physics Model has only one hypothesis, that outflow is proportional to level. The Physics Model exactly replicates the 14C data from 1970 to 2014 with only two physical parameters: balance level and e-time. The 14C data trace how CO2 flows out of the atmosphere. The Physics Model shows the 14 CO2 e-time is a constant 16.5 years. Other data show e-time for 12CO2 is about 4 to 5 years. IPCC claims human CO2 reduces ocean buffer capacity. But that would increase e-time. The constant e-time proves IPCC’s claim is false. IPCC argues that the human-caused reduction of 14C and 13C in the atmosphere prove human CO2 causes all the increase in atmospheric CO2. However, numbers show these isotope data support the Physics Model and reject the IPCC model. The Physics Model shows how inflows of human and natural CO2 into the atmosphere set balance levels proportional to their inflows. Each balance level remains constant if its inflow remains constant. Continued constant CO2 emissions do not add more CO2 to the atmosphere. No CO2 accumulates in the atmosphere. Present human CO2 inflow produces a balance level of about 18 ppm. Present natural CO2 inflow produces a balance level of about 392 ppm. Human CO2 is insignificant to the increase of CO2 in the atmosphere. Increased natural CO2 inflow has increased the level of CO2 in the atmosphere.” ~ Edwin X Berry, Human CO2 Emissions Have Little Effect on Atmospheric CO2, International Journal of Atmospheric and Oceanic Sciences. Volume 3, Issue 1, June 2019 , pp. 13-26. doi: 10.11648/j.ijaos.20190301.13.




  • Edwin Berry, PhD. is CEO of Climate Physics, LLC, in Bigfork, Montana. He received his BS in Engineering from Caltech, his MA in Physics from Dartmouth, and his PhD in Physics from the University of Nevada.  At Dartmouth, Berry studied probability and Markov chains and philosophy of science under John Kemeny, a student of Albert Einstein. At Nevada, Berry studied physics under Friedwart Winterberg, Heisenberg’s best student, and William T. Scott.  https://orcid.org/0000-0003-4699-0866
  • Murry Lewis Salby, PhD., deceased 2022, received his doctorate in environmental dynamics in 1978 at the Georgia Institute of Technology.  He was an American atmospheric scientist who focused on upper atmospheric wave propagation. He wrote two textbooks, Fundamentals of Atmospheric Physics (1996), and Physics of the Atmosphere and Climate (2012).
  • Tom V. Segalstad, PH.D. is associate professor of resource and environmental geology at the University of Oslo and head of the university’s Geological Museum. Dr. Segalstad has conducted research, publishing, and teaching in geochemistry, mineralogy, petrology, volcanology, structural geology.
  • Roy W Spencer, PhD. received his Ph.D. in meteorology from the University of Wisconsin–Madison in 1982.  He is principal research scientist at the University of Alabama in Huntsville, and the U.S. Science Team leader for the Advanced Microwave Scanning Radiometer (AMSR-E) on NASA’s Aqua satellite. He has served as senior scientist for climate studies at NASA’s Marshall Space Flight Center and is known for his satellite-based temperature monitoring work, for which he was awarded the American Meteorological Society’s Special Award.
  • Werner Stumm was a Swiss chemist. After earning his doctorate in inorganic chemistry at the University of Zürich in 1952 he moved to the U.S. where he was active as a professor at Harvard University until 1969. From 1970 until 1992 he was head of the Swiss Federal Water Resources Centre EAWAG.  Werner Stumm was an active researcher in several aspects of geochemistry. During the early part of his career, he was influenced by the ideas of Lars Gunnar Sillén and Robert Garrels regarding aqueous chemical equilibria. He developed models where the ideas by Sillén regarding equilibria were combined with improved descriptions of kinetically controlled reactions (i.e., slow reactions that do not reach equilibrium, e.g., weathering).  Stumm is well known for writing the influential book Aquatic chemistry, together with James J. Morgan, and several other books on the interplay between mineral surfaces and water.