Historical CO2 levels

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Is the idea that Carbon dioxide levels used to be both low and stable - another IPCC myth?


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The IPCC's CO2 trick

Another of the IPCC tricks, well-hidden (buried under mountains of Energy department paid trivia publicised by the likes of the Guardian and Realclimate) is the ludicrous claim that CO2 levels have been historically stable, and are now exceptionally high, leading to - you -know-what (okay, a runaway greenhouse warming effect).

Here 1 , the International Herald Tribune repeats the trick:

... the combustion of fossil fuels by humans since the Industrial Revolution has increased atmospheric carbon dioxide concentrations by about 40 percent, to a level substantially higher than at any other time in the last 800,000 years.

A paper called: 180 YEARS OF ATMOSPHERIC CO2 GAS ANALYSIS BY CHEMICAL METHODS by Ernst-Georg Beck 2 reveals the trick.

More than 90,000 accurate chemical analyses of CO2 in air since 1812 are summarised. The historic chemical data reveal that changes in CO2 track changes in temperature, and therefore climate in contrast to the simple, monotonically increasing CO2 trend depicted in the post-1990 literature on climate-change. Since 1812, the CO2 concentration in northern hemispheric air has fluctuated exhibiting three high level maxima around 1825, 1857 and 1942 the latter showing more than 400 ppm

Interesting, no? Not to the 'scientists'! Look at this typical response from a typical Alarmist expert commenting anonymously on the Guardian website! (Is it George Monbiot?)

That's the level of debate for the Alarmists! They don't like measurements.. they prefer theoretical models.

The paper touches upon probably an equally serious error in the Alarmist camp to the rubbish 'hockey stick' temperature theory, which insisted that temperatures never used to vary - until a few years ago (no Medieval Warm Period, etc etc), and that today's temperatures are unprecedented.

The IPCC has backtracked on that temperature record 'slightly', but not on CO2 levels. Their version of history is still trotted out. This paper points out that the selection of CO2 measurements to support their claim is no better than the selection of temperature measures to support Michael Mann's hockey stick.

The point of Beck's paper is that: "the selective way in which they discarded previous data, are not able to be justified. Their most egregious error was perhaps the dismissal of all data which showed variations from their presupposed average."

Criticism of Beck's analysis

Ernst Beck did a monumental and careful job of assembling the historical database
of quality CO2 measurements. However, because they come from many different locations and observers, they have been accused of being merely a pastiche of local, measurements. Climate 'Alarmists' instead point at a rival series of measures, the Scripps measurements from the top of Mauna Loa, and say that this offes the 'true' picture of 'global CO2'. They argue that because the volcano sticks up into the high troposphere, and is far from any possible industrial or human source, there's a fair chance that the numbers really are representative of the atmosphere at large (apart from the fact
that there's an active volcano near by, but that's another story).

Here's one such critique:

Comment on "180 Years of atmospheric CO2 gas analysis by chemical methods" by Ernst-Georg Beck. Ralph F. Keeling

(The obvious source is the sea, which contains It contains 39 000 Gt of carbon. A figatonne is a billin tonnes.)

But look what follos next in this scholarly paper!

By comparison, the 'warmist' carbon sites offer CO2 increases such as 75 ppm in 50 years at 'MLO'
and 50 ppm in 30 years at 'SAM'. Taking the second for convenience, we are equally supposed to have added 100 billion metric tonnes of carbon to the atmosphere, or about 'on sixth' of "of all the carbon contained in land plants globally". Yet the warmists have no problem with 'too much carbon' when it suits them!

The criticism of Beck and his work has been highly partisan, and includes much venom. More to the point, it includes many ill-informed comments on the accuracy of 'Victorian chemists'. In fact, the techniques used in even 'Victorain' measurements had an excellent accuracy, plus chemists are aware that CO2 levels vary naturally all the time. One later set of measurements in 1939, by the famous expert in gas analysis, Paul Schuftan demonstrates well both the seasonal cycle and weather events around the city of Giessen, a 20ppm upward influence on levels of the city itself, and confirms strikingly the persistence of CO2 levels above 400 ppm over most of a period of 2 years.

Beck's point again:

"The selective way in which they [the authors quoted by the IPCC] discarded previous data, are not able to be justified. Their most egregious error was perhaps the dismissal of all data which showed variations from their presupposed average."

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How the CO2 'norm' was contrived to fit a theory

How did the figure, somehow rather imposing, of "280 parts per million" became the figure accepted by the IPCC? It idid this, even though there was overwhelming documentary evidence (as summarised by Beck) to show this figure was rather on the low side, and levels anyway are subject to much more fluctuation than modern records seem to indicate.

The science of CO2 measurements has been greatly influenced by the measurements taken by a steam engineer and amateur meteorologist called G S Callendar. For Climate Alarmists, Callendar is 'the Father of the AGW theory'. Certainly, he influenced one Charles Keeling, the American whose pronouncements on the subject are taekn as gospel by the IPCC.

Callendar analysed just one set of data on atmospheric CO2 content taken at Kew, near London, between 1898 and 1900. These data were taken near a source of CO2 and were analytically very uncertain. From this analysis, he concluded that at around 1900 the free atmosphere over the North Atlantic region contained 274 ± 5 parts per million (p.p.m.) of CO2. Then, after arguing that only a small fraction of the CO2 from combustion of fossil fuels would dissolve in the ocean, he calculated from an estimated global production rate of CO2 the amount that he thought would be there in 1936 (290 p.p.m.), 2000 (314–317), 2100 (346–358) and 2200 (373–396).

With a simple model of the absorption of infrared radiation, he worked out the amount of global warming to be expected from his predicted CO2 levels, concluding that temperature would then have been increasing at a rate of about 0.03 °C per decade. Callendar’s 1938 attribution of early twentieth-century warming to CO2 increase might have made him a cause celebre in his lifetime - had it not been that the planet plunged into a several periods of global cooling.

IN the 1940s, Charles Keeling consulted with Callendar as they began their research programs, and was given the “Callendar effect” — the conviction that climatic change is brought about by anthropogenic increases in the concentration of atmospheric carbon dioxide, primarily through the processes of combustion.

INcredible though it may seem, Callendar's circular methodology is accepted. I examining earlier CO2 measurements, he assumed his theory was correct and disregarded all measurements that contradicted it. The remaining figures, he then used to 'justify' his originally assumed figures. In other words, he examined 19th and 20th century CO2 measurements, and rejected those he considered inaccurate for a variety of reasons, and the ones left 'led him' to conclude that the pre-industrial CO2 level was about 290 ppm [footnote(G. S. Callendar, “The Composition of the Atmosphere through the Ages,” The Meteorological Magazine,vol. 74, No. 878, March 1939, pp. 33-39.)] This seemingly low 280/290ppm figure is the one that Charles Keeling subsequently accepted, and became thus 'the starting point' for all the IPCC scarey CO2 levels graphs.

Among the criteria that Callendar used to reject measurements were any that deviated by 10% or more from the average of the region, and any taken for special purposes such as such as “biological, soil, air, atmospheric pollution”. The first criteria is said to be a rather circular argument, while the second seems to ignore the accuracy of the results. Whatever the validity of these exclusions, it turned out that the mean of 19th century samples he chose to include was 292 ppm. The mean of the samples he had available to include was 335-350 ppm (although these would have been towards the top end of the spread).

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