Correct Timing is Everything - Also for CO 2 in the Air



Guest Editorial by Tom V. Segalstad

Associate Professor of Resource and Environmental Geology

The University of Oslo, Norway



Volume 12, Number 31: 5 August 2009

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In a paper recently published in the international peer-reviewed journal Energy & Fuels, Dr. Robert H. Essenhigh (2009), Professor of Energy Conversion at The Ohio State University, addresses the residence time (RT) of anthropogenic COin the air. He finds that the RT for bulk atmospheric CO, the moleculeCO, is ~5 years, in good agreement with other cited sources (Segalstad, 1998), while the RT for the trace moleculeCOis ~16 years. Both of these residence times are much shorter than what is claimed by the IPCC. The rising concentration of atmospheric COin the last century is not consistent with supply from anthropogenic sources. Such anthropogenic sources account for less than 5% of the present atmosphere, compared to the major input/output from natural sources (~95%). Hence, anthropogenic COis too small to be a significant or relevant factor in the global warming process, particularly when comparing with the far more potent greenhouse gas water vapor. The rising atmospheric COis the outcome of rising temperature rather than vice versa. Correspondingly, Dr. Essenhigh concludes that the politically driven target of capture and sequestration of carbon from combustion sources would be a major and pointless waste of physical and financial resources.

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Essenhigh (2009) points out that the IPCC (Intergovernmental Panel on Climate Change) in their first report (Houghton et al., 1990) gives an atmospheric CO 2 residence time (lifetime) of 50-200 years [as a "rough estimate"]. This estimate is confusingly given as an adjustment time for a scenario with a given anthropogenic CO 2 input, and ignores natural (sea and vegetation) CO 2 flux rates. Such estimates are analytically invalid; and they are in conflict with the more correct explanation given elsewhere in the same IPCC report: "This means that on average it takes only a few years before a CO 2 molecule in the atmosphere is taken up by plants or dissolved in the ocean".

Some 99% of the atmospheric CO 2 molecules are 12 CO 2 molecules containing the stable isotope 12 C (Segalstad, 1982). To calculate the RT of the bulk atmospheric CO 2 molecule 12 CO 2 , Essenhigh (2009) uses the IPCC data of 1990 with a total mass of carbon of 750 gigatons in the atmospheric CO 2 and a natural input/output exchange rate of 150 gigatons of carbon per year (Houghton et al., 1990). The characteristic decay time (denoted by the Greek letter tau) is simply the former value divided by the latter value: 750 / 150 = 5 years. This is a similar value to the ~5 years found from 13 C/ 12 C carbon isotope mass balance calculations of measured atmospheric CO 2 13 C/ 12 C carbon isotope data by Segalstad (1992); the ~5 years obtained from CO 2 solubility data by Murray (1992); and the ~5 years derived from CO 2 chemical kinetic data by Stumm & Morgan (1970).

Revelle & Suess (1957) calculated from data for the trace atmospheric molecule 14 CO 2 , containing the radioactive isotope 14 C, that the amount of atmospheric "CO 2 derived from industrial fuel combustion" would be only 1.2% for an atmospheric CO 2 lifetime of 5 years, and 1.73% for a CO 2 lifetime of 7 years (Segalstad, 1998). Essenhigh (2009) reviews measurements of 14 C from 1963 up to 1995, and finds that the RT of atmospheric 14 CO 2 is ~16 (16.3) years. He also uses the 14 C data to find that the time value (exchange time) for variation of the concentration difference between the northern and southern hemispheres is ~2 (2.2) years for atmospheric 14 CO 2 . This result compares well with the observed hemispheric transport of volcanic debris leading to "the year without a summer" in 1816 in the northern hemisphere after the 1815 Tambora volcano cataclysmic eruption in Indonesia in 1815.

Sundquist (1985) compiled a large number of measured RTs of CO 2 found by different methods. The list, containing RTs for both 12 CO 2 and 14 CO 2 , was expanded by Segalstad (1998), showing a total range for all reported RTs from 1 to 15 years, with most RT values ranging from 5 to 15 years. Essenhigh (2009) emphasizes that this list of measured values of RT compares well with his calculated RT of 5 years (atmospheric bulk 12 CO 2 ) and ~16 years (atmospheric trace 14 CO 2 ). Furthermore he points out that the annual oscillations in the measured atmospheric CO 2 levels would be impossible without a short atmospheric residence time for the CO 2 molecules.

Essenhigh (2009) suggests that the difference in atmospheric CO 2 residence times between the gaseous molecules 12 CO 2 and 14 CO 2 may be due to differences in the kinetic absorption and/or dissolution rates of the two different gas molecules.

With such short residence times for atmospheric CO 2 , Essenhigh (2009) correctly points out that it is impossible for the anthropogenic combustion supply of CO 2 to cause the given rise in atmospheric CO 2 . Consequently, a rising atmospheric CO 2 concentration must be natural. This conclusion accords with measurements of 13 C/ 12 C carbon isotopes in atmospheric CO 2 , which show a maximum of 4% anthropogenic CO 2 in the atmosphere (including any biogenic CO 2 ), with 96% of the atmospheric CO 2 being isotopically indistinguishable from "natural" inorganic CO 2 exchanged with and degassed from the ocean, and degassed from volcanoes and the Earth's interior (Segalstad, 1992).

Essenhigh (2009) discusses alternative ways of expressing residence time, like fill time, decay time, e-fold time, turnover time, lifetime, and so on, and whether the Earth system carbon cycle is in dynamic equilibrium or non-equilibrium status. He concludes (like Segalstad, 1998) that the residence time is a robust parameter independent of the status of equilibrium, and that alternative expressions of the residence time give corresponding values.

It is important to compare Essenhigh's (2009) results with a recently published paper in PNAS by Solomon et al. (2009), the first author of which (Susan Solomon) co-chairs the IPCC Working Group One, the part of the IPCC that deals with physical climate science. This paper was published after Essenhigh had submitted his manuscript to Energy & Fuels.

The message of Solomon et al. (2009) is that there is an irreversible climate change due to the assimilation of CO 2 in the atmosphere, solely due to anthropogenic CO 2 emissions. From quantified scenarios of anthropogenic increases in atmospheric CO 2 , their implication is that the CO 2 level flattens out asymptotically towards infinity, giving a residence time of more than 1000 years (without offering a definition or discussion of residence time or isotopic differences): "a quasi-equilibrium amount of CO 2 is expected to be retained in the atmosphere by the end of the millennium that is surprisingly large: typically ~40% of the peak concentration enhancement over preindustrial values (~280 ppmv)". The authors' Fig. 1, i.a. shows a peak level at 1200 ppmv atmospheric CO 2 in the year 2100, levelling off to an almost steady level of ~800 ppmv in the year 3000. It is not known how their 40% estimate was derived.

Solomon et al. (2009) go on to say that "this can be easily understood on the basis of the observed instantaneous airborne fraction (AFpeak) of ~50% of anthropogenic carbon emissions retained during their build-up in the atmosphere, together with well-established ocean chemistry and physics that require ~20% of the emitted carbon to remain in the atmosphere on thousand-year timescales [quasi-equilibrium airborne fraction (AFequil), determined largely by the Revelle factor governing the long-term partitioning of carbon between the ocean and atmosphere/biosphere system]".

Solomon et al. (2009) have obviously not seriously considered the paper by Segalstad (1998), who addresses the 50% "missing sink" error of the IPCC and shows that the Revelle evasion "buffer" factor is ideologically defined from an assumed model (atmospheric anthropogenic CO 2 increase) and an assumed pre-industrial value for the CO 2 level, in conflict with the chemical Henry's Law governing the fast ~1:50 equilibrium partitioning of CO 2 between gas (air) and fluid (ocean) at the Earth's average surface temperature. This CO 2 partitioning factor is strongly dependent on temperature because of the temperature-dependent retrograde aqueous solubility of CO 2 , which facilitates fast degassing of dissolved CO 2 from a heated fluid phase (ocean), similar to what we experience from a heated carbonated drink.

Consequently, the IPCC's and Solomon et al.'s (2009) non-realistic carbon cycle modelling and misconception of the way the geochemistry of CO 2 works simply defy reality, and would make it impossible for breweries to make the carbonated beer or soda "pop" that many of us enjoy (Segalstad, 1998).

So why is the correct estimate of the atmospheric residence time of CO 2 so important? The IPCC has constructed an artificial model where they claim that the natural CO 2 input/output is in static balance, and that all CO 2 additions from anthropogenic carbon combustion being added to the atmospheric pool will stay there almost indefinitely. This means that with an anthropogenic atmospheric CO 2 residence time of 50 - 200 years (Houghton, 1990) or near infinite (Solomon et al., 2009), there is still a 50% error (nicknamed the "missing sink") in the IPCC's model, because the measured rise in the atmospheric CO 2 level is just half of that expected from the amount of anthropogenic CO 2 supplied to the atmosphere; and carbon isotope measurements invalidate the IPCC's model (Segalstad, 1992; Segalstad, 1998).

The correct evaluation of the CO 2 residence time -- giving values of about 5 years for the bulk of the atmospheric CO 2 molecules, as per Essenhigh's (2009) reasoning and numerous measurements with different methods -- tells us that the real world's CO 2 is part of a dynamic (i.e. non-static) system, where about one fifth of the atmospheric CO 2 pool is exchanged every year between different sources and sinks, due to relatively fast equilibria and temperature-dependent CO 2 partitioning governed by the chemical Henry's Law (Segalstad 1992; Segalstad, 1996; Segalstad, 1998).

Knowledge of the correct timing of the whereabouts of CO 2 in the air is essential to a correct understanding of the way nature works and the extent of anthropogenic modulation of, or impact upon, natural processes. Concerning the Earth's carbon cycle, the anthropogenic contribution and its influence are so small and negligible that our resources would be much better spent on other real challenges that are facing mankind.

Tom V. Segalstad

Associate Professor of Resource and Environmental Geology

The University of Oslo, Norway

Personal web page: www.CO2web.info

References

Essenhigh, R.E. 2009: Potential dependence of global warming on the residence time (RT) in the atmosphere of anthropogenically sourced carbon dioxide. Energy & Fuels 23: 2773-2784.

Houghton, J.T., Jenkins, G.J. & Ephraums, J.J. (Eds.) 1990: Climate Change. The IPCC Scientific Assessment. Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge: 365 pp.

Murray, J.W. 1992: The oceans. In: Butcher, S.S., Charlson, R.J., Orians, G.H. & Wolfe, G.V. (Eds.): Global biogeochemical cycles. Academic Press: 175-211.

Revelle, R. & Suess, H. 1957: Carbon dioxide exchange between atmosphere and ocean and the question of an increase of atmospheric CO 2 during past decades. Tellus 9: 18-27.

Segalstad, T. V. 1982: Stable Isotope Analysis. In: Stable Isotopes in Hydrocarbon Exploration, Norwegian Petroleum Society 6904, Stavanger: 21 pp. Available at: http://www.co2web.info/STABIS-ANAL.pdf

Segalstad, T. V. 1992: The amount of non-fossil-fuel CO 2 in the atmosphere. AGU Chapman Conference on Climate, Volcanism, and Global Change. March 23-27, 1992. Hilo, Hawaii. Abstracts: 25; and poster: 10 pp. Available at: http://www.co2web.info/hawaii.pdf

Segalstad, T. V. 1996: The distribution of CO 2 between atmosphere, hydrosphere, and lithosphere; minimal influence from anthropogenic CO 2 on the global "Greenhouse Effect". In Emsley, J. (Ed.): The Global Warming Debate. The Report of the European Science and Environment Forum. Bourne Press Ltd., Bournemouth, Dorset, U.K. [ISBN 0952773406]: 41-50. Available at: http://www.co2web.info/ESEFVO1.pdf

Segalstad, T. V. 1998: Carbon cycle modelling and the residence time of natural and anthropogenic atmospheric CO 2 : on the construction of the "Greenhouse Effect Global Warming" dogma. In: Bate, R. (Ed.): Global warming: the continuing debate. ESEF, Cambridge, U.K. [ISBN 0952773422]: 184-219. Available at: http://www.co2web.info/ESEF3VO2.pdf

Solomon, S., Plattner, G.-K., Knutti, R. & Friedlingstein, P. 2009: Irreversible climate change due to carbon dioxide emissions. Proceedings of The National Academy of Sciences of the USA [PNAS] 106, 6: 1704-1709.

Stumm, W. & Morgan, J.J. 1970: Aquatic chemistry: an introduction emphasizing chemical equilibria in natural waters. Wiley-Interscience: 583 pp.