Friday, April 04, 2014

Critique of Segalstad's theory of natural sources of CO2 in the atmosphere.

In our debate on climate change, my Objectivist friend "Son of John Galt" (@MDSebach) agrees that

  • there is a greenhouse effect, agrees 
  • that CO2 is a greenhouse gas, and agrees 
  • that the level of CO2 has risen,
  • believes that the source of the increase is natural outgassing of CO2 from oceans - and also volcanoes.
This line begs the question - what has caused the oceans and volcanoes to pump out more CO2 since 1850?

His argument is in the comments section of the debate post. 

He relies chiefly on Dr Tom Segalstad, who is a Norwegian geologist, not a climatologist, and who has not published his theory in any peer reviewed journal. Segalstad puts his case here.

This is not a promising start. There are scores of armchair amateur climatologists in existence, each with their pet theory, and looking them up and doing the critique takes time. Which is, of course, fulfilling the aim of the skeptics' game. Theirs is a delaying tactic, to hold the world back from doing what it is going to have to do, namely, decarbonise the economy.

But I am going to carry on, partly because I like Norwegians, and partly because Segalstad has not had much of a critique in English. Three oceanographers, Bellerby, Olsen and Nondal published a critique of Segalstad's theory in Norwegian in 2008 here. I am very grateful to them.

This is a machine translation. I have tweaked it a bit to remove some Norwegian constructions.

Atmospheric CO2 increase is man made

Associate Professor Tom v. Segalstad calls today's CO2-debate "a political process, which is not wanted to lean on the nature of the chemical realities". The fact is that neither the long-established laws or geochemical measurements Segalstads supports the reasoning or conclusion.

Segalstad provides, among others, the impression that there is no CO2 emissions as a result of human activity that is the main reason for the increase of the CO2 content in the atmosphere (see Figure 1), but that the warming of the oceans is leading to outgassing of the carbon dioxide from the ocean to the atmosphere.
Figure 1. Increase in the atmospheric content of CO2 (in ppm) from Mauna Loa, Hawaii (19 ° N, blue color) and Baring Head, New Zealand (43 ° S, red color). Readings from various stations around the globe shows all the same trend. (Keeling and Whorf 2005).

It is fruitful to debate, but it is problematic when the line of argument is based on the actual wrong interpretations.

In the following, we will go through the Segalstads most important arguments and show that these are contrary to the well-established geochemical laws and considerations. In addition, we present measurements as a unique show that the increase of CO2 in the atmosphere is due, essentially, the use of fossil fuels. The observations also show, completely unambiguously, that the world's oceans take up carbon dioxide from the atmosphere.

An ever-warmer ocean can not explain the atmospheric CO2 increase

The cause of the increase of atmospheric CO2 are mainly the burning of coal, oil, and gas. Between 1751 and 2004 there have been let out around 315 gigatonnes of carbon (Gt C, Marland and others. 2007). This is equivalent to 53 percent of it before-industrial content of CO2 in the atmosphere, and is without a doubt a significant contribution.

Segalstad, gives the impression that the sea is the main source when he says that "there will be more CO2 in the air when it gets warmer, because a warmer seas can not hold on to so much CO2".

Henry's law is a long-established law in the field of physical chemistry, and it describes the relationship between the concentration of CO2 in the ocean, the atmosphere, and the solubility of CO2 in the ocean.

Two effects of Henry's law is important in today's climate debate: 
(1) when the atmospheric content of CO2 increases, the ocean's uptake of carbon dioxide will increase, and 
(2) a warming of the ocean will lead to the outgassing of CO2 because solubility decreases when it gets warmer.

These effects will counteract each other in today's world. It was so that the latter effect dominated, an impression one can get by the Segalstads initiative, as would one necessarily observed a reduction in the content of dissolved inorganic carbon (the sum of the dissolved CO2, bicarbonate-(HCO3-) and karbonationer (CO32-)), and then with the strongest decrease in the ocean's surface layer.

Observation shows on the contrary that the content of dissolved inorganic carbon increases with time in all the world's oceans (Sabine m. fl. 1999, Peng and others. 2003, Olsen and others., 2006), and the increase is greatest in and near the ocean's surface (Figure 2).

Fig 2
Figure 2. The increase of the content of dissolved inorganic carbon (in mmol kg-1) in the Nordic seas from 1981 to 2002/2003 (Olsen and others. 2006), corrected for changes in temperature, salt and industrial salts. The relatively modest increase in the surface in the Lofotenbassenget and parts of the Greenland Sea is caused by the interference of the polar bodies of water that have taken up less carbon than water from the Atlantic Ocean (the Atlantic water is seen as carbon-enriched water flowing nordøver via Færøybanken towards the Norwegian Sea).

This is fully in line with Henry's law; the increase in the atmospheric content of CO2 resulting from the use of fossil fuels leads to that the sea takes up more CO2. This process is far more important than outgassing as a result of a temperature rise.

Calculations based on a published and widely accepted relationship between change in the carbon dioxide content of the air and the change of the sea-water temperature (Takahashi m. fl. 1993) shows that this can, as an absolute maximum, only explain 10 percent of the increasing CO2 content in the atmosphere (from 280 ppm, pre-industrial value, to 380 ppm, the current value).

In order to achieve the same increase via a fumigation alone, we can calculate that the surface temperature of the sea, will have to increase by 7.4 ° c. A temperature increase of well 7 degrees is in stark contrast to the observed increase in global average temperature of the sea surface at around 0.8 C. Accordingly, it is, in line with the measurements in the oceans and atmosphere, just the burning of fossil fuels which may be the main reason for the CO2 increase.

Segalstads isotope argument is misleading

Carbon is available as three different isotopes: 12 c, 13, and 14 c. Plants prefer the lightweight carbon isotope 12 c in photosynthesis, and therefore have a lower 13/12 c ratio (ð13C) than atmospheric CO2. Since fossil fuels are built up from organic plant material, the emissions of CO2 from the use of fossil fuels lead to decreasing values of ð13C in the atmosphere (Figure 3).
Figure 3. Monthly measurements of ð13C from Mauna Loa, Hawaii (blue color) and Baring Head, New Zealand (red color). As for the atmospheric CO2 increase in Figure 1 also shows the measurements from different stations around the globe the same trend in the ð13C (Keeling and others. 2005).

This is known as the Suess effect. In the same way we observe that atmospheric oxygen content decreases because the combustion consumes oxygen (Manning and Keeling 2006).

Segalstad argues, based on its own calculations, that the "carbon, it in the oxygen in CO2 is the absolute proof that human impact is minimal (a maximum of 4 per cent)". What percent is correct, but the conclusion is incorrect. The reason why no more than 4 percent of the atmospheric CO2 can be traced directly to human emissions is that it all the time going on an exchange of CO2 between the ocean, the atmosphere and the biosphere.

Each year leads to the natural processes that it exchanged CO2 equivalent 90 Gt C between the ocean and the atmosphere (in addition to a net-recording in the sea of about 2.2 Gt C, Manning and Keeling 2006). The important thing about this is that the ocean is relatively less affected by the CO2 from fossil fuels than the atmosphere. Therefore, the ocean to a greater extent take up than free up CO2 with the isotopiske signature of fossil fuels.

Measurements over time has shown that the ð13C is sinking into the Ocean (Gruber and others. 1999, Olsen and others. 2006), see Figure 4, which is consistent with the fact that the ocean takes up carbon dioxide with the isotopic signature of fossil fuels. It is clear that this mutes the Suess effect in the atmosphere.
Figure 4. Change in the ð13C because of the Suess effect in the Nordic seas from 1981 to 2003 (Olsen and others., 2006). The low values in the top 1000 m due to the ocean's uptake of carbon dioxide from the atmosphere planteberiket. Otherwise, see the comment about Lofotenbassenget and parts of the Greenland Sea from Figure 2.

Segalstads calculations tell us nothing about the net, therefore, the increase of CO2 in the atmosphere, but on the other hand about how much of the carbon dioxide molecules that can be traced directly to the fossil sources. No one argues that the increase of CO2 in the atmosphere is made up of the self-same CO2-molecules which one has dropped out, even though the number of carbon dioxide molecules increases.

Climate impact will of course be the same regardless of the origin of the carbon dioxide molecules. We do not see that Segalstad mentions this, which we find unreasonable and misleading.

Segalstad is wrong

We have shown that Segalstad mistaken regarding the cause of the observed increase in the atmospheric content of CO2.

He bases his argument on the incorrect interpretations of the geochemical data statutes and, in addition to a complete neglect of the published polls as a unique show that the atmospheric CO2 increase is mainly man made (1) and (2) that the ocean takes up carbon dioxide from the atmosphere.

It is also worth noting that Segalstad have not yet published their assumptions in a recognised scientific journal (in spite of that he says he has claimed these perceptions for 20 years).

Consequently, his statement only opinion that do not belong to the scientific literature on the subject field.


Gruber, N. m. fl., 1999. Spatiotemporal patterns of carbon-13 in the global surface oceans and the oceanic Suess effect. Global Biogeochemical Cycles, 13, 307-335.

Keeling, C. D. og T. P., Whorf. 2005. Atmospheric CO2 records from sites in the SIO air sampling network. Ii: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A

Keeling, C. D. m. fl., 2005: Monthly atmospheric 13C/12C isotopic ratios for 10 SIO stations. Ii: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A

Manning, A. C., og R. F. Keeling, 2006: Global oceanic and land biotic carbon sinks from the Scripps atmospheric oxygen flask sampling network. Tellus, 52B (2), 95-116.

Marland, G. m. fl., 2007. Global, Regional, and National CO2 Emissions. I Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.

Olsen, A., m. fl., 2006. Magnitude and origin of the anthropogenic CO2 increase and 13C Suess effect in the Nordic Seas since 1981. Global Biogeochemical Cycles, to (GB3027), doi: 10.1029/2005GB002669.

Peng, T. H. m. fl., 2003, Increase of anthropogenic CO2 in the Pacific Ocean over the last two decades, Deep-Sea Research II 50, 3065-3082.

Sabine, C. R. m.fl., 1999, Anthropogenic CO2 inventory in the Indian Ocean, Global Biogeochemical Cycles, 13, 179-198.

Takahashi m. fl., 1993. Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: A comparative study. Global Biogeochemical Cycles 7, 843-878.

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