The Carbon Cycle and Royal Society Math

By Dr. Klaus L.E. Kaiser  Wednesday, October 13, 2010, CFP

The recent “rebellion” by senior members of the Royal Society (RS) forced it to revise their guide “Climate change: a summary of the science”. The new guide, published on 30 September 2010, has a single paragraph under the heading The Carbon Cycle and Climate. In that, it says:

“Current understanding indicates that even if there was a complete cessation of emissions of CO2 today from human activity, it would take several millennia for CO2 concentrations to return to preindustrial concentrations” [emphasis added].

One can easily (on the back of an envelope) calculate the order of magnitude of the amounts of carbon currently present in the atmosphere, and those burned in the world, hence the amounts of CO2 produced (assuming complete combustion). The former leads to approximately 5×10^14 kg C present in the atmosphere (of course in the form of CO2). The latter computes to 0.4×10^13 kg C (as CO2) per annum from oil, 0.7×10^13 from coal [1], or 10^13 kg C from coal and oil together. Any additional amounts from the combustion of natural gas and biofuels, or from natural sources (volcanoes) are excluded [2].

On that basis, if there were no CO2 removal processes, the CO2 concentration in the atmosphere should double every 15 years. But, in fact, over the last 100 years, at most it has increased by only 1/3, i.e. approximately from 300 to 400 ppm (parts per million in weight).

The much lower than expected increase (based on fossil fuel consumption) in the atmospheric CO2 can only be explained by a strong (natural) removal process.

It is also obvious then that the statement by the Royal Society that it would take “millennia” for atmospheric CO2 to return to levels at preindustrial times upon a (theoretical) complete and sudden cessation of all manmade CO2 release to the atmosphere cannot be true. If the CO2 were to stay in the atmosphere for millennia, why has its level in the atmosphere not doubled in the last 15 years, or gone up tenfold-plus over the last 100 hundred years? Furthermore, there are several peer-reviewed papers reporting the half life of CO2 in the atmosphere to be between 5 and 10 years. A half life of 5 years means that more than 98% of a substance will disappear in a time span of 30 years.

Obviously, that begs the question: WHAT IS WRONG HERE?


But, what else does it mean? Again, that is easy to answer:

  1. First, it means that the turnover rate (addition to and removal from the air) of CO2 is orders of magnitude faster than implied by the RS statement.
  2. It means that CO2 in the atmosphere is rapidly being taken up by the plants on land and even more so by the oceans. In the oceans CO2 gets converted to organic matter through photosynthesis. That is the process from which essentially all life on earth is derived. If the statement by the RS about the longevity of CO2 in the atmosphere were true, CO2 levels in the air would have increased—from mankind’s influence alone – not just by a few percent, but by a factor of 2 or so over the last one and one-half decades alone. Clearly that is not the case.
  3. It further means that, when adding the large emissions of CO2 from natural processes [2, 3], to those from man’s activities into the calculations above, atmospheric CO2 would have had to increase even more over the last decade alone. Clearly that is not the case.
  4. Last not least, it means that the whole CO2-climate-change scenario, as portrayed by the RS (and many others for that matter) is in shambles. As the CO2 from mankind’s burning of fossil fuels and possibly larger emissions from natural sources is consumed by organisms on land and in the water at a rate nearly identical to that of its production, it could not possibly take “several millennia” to return to a pre-industrial level upon a (theoretical) cessation of all of mankind’s CO2 emissions.

In summary

The Royal Society’s claim that it would take millennia for CO2 from human activity to dissipate from the atmosphere is clearly untenable. However, it would also appear inconceivable to think that the RS would not have done a few of such simple order-of-magnitude calculations, as shown above, to confirm the veracity of their claims. Therefore, even though it took months to prepare that document, it appears the Royal Society’s math is still wrong.


[1]. Wikipedia, Coal .

[2]. The assumptions used are: (a) Earth atmosphere of 10 km thickness, at 1 bar; (b) CO2 level in the atmosphere 400 ppm (part per million (weight units); (c) mass of carbon (C) in CO2: one quarter; (d) world consumption of oil per day: 85 million barrels; (e) one barrel oil = 150 L = 150 kg C; (f) world consumption of coal per year: 0.7 x 10^13 kg (in 2008); (g) world consumption of natural gas and biofuel (wood, dung, etc.) per day: estimated as 50 million barrels of oil (equivalent).

[3]. For example, the Kilauea volcano on the Island of Hawaii (not very far from the Mauna Loa Observatory run by the National Oceanographic and Atmospheric Administration, NOAA) alone is estimated to emit 9×10^6 kg CO2 per day, or 10^9 kg C per year [4]. Of course, there are thousands of other volcanic vents, above ground and below the sea, which also emit CO2 on a continuous basis, not to mention the occasional but massive eruptions of volcanoes which have been dormant for many years, such as on Iceland earlier this year.

[4]. Gerlach TM, McGee KA, Ekiast T, Sutton AJ, Doukas MP, 2002. Carbon dioxide emission rate of Kīlauea Volcano: Implications for primary magma and the summit reservoir. Journal of geophysical research, 107: ECV3.1-ECV 3.15.

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