Time now to discuss the science behind CO2 and how it has managed to arrive front and centre in every discussion on cAGW/Climate Change.
Although it might seem to be a very recent phenomenon, CO2, as an influence on the atmosphere, has a long and interesting history. Despite what you may read, people have been measuring atmospheric CO2 since the early 1800s. When you look back at these measurements, you will realise that we are a long way from reaching any sort of ‘tipping point’.
Currently, CO2 levels stand at ~395 ppm and the alarmists state that 350-360 ppm is an ideal level. No one knows, or at least I’ve never been able to discover, exactly how they arrive at that figure. Like most things in this arena, it appears that a number has been pulled out of a hat and allocated some sort of ‘mystical’ significance.
If you click on the image and study the dots, you might notice that back in the early 1800s the mean values of atmospheric CO2 reached levels of at least 550 ppm.
One of the key tenets of cAGW, and its link to anthropogenic CO2 (ACO2), is that pre-industrial levels were in the order of ~280 ppm and the recent rise in CO2 levels correlates with the rise in post-industrial temperatures, therefore correlation = causation (remember that link?).
Before I move on, I would like to quote a little piece of the article to provide some background for what is to follow.
The notion of low pre-industrial CO2 atmospheric level, based on such poor knowledge, became a widely accepted Holy Grail of climate warming models. The modelers ignored the evidence from direct measurements of CO2 in atmospheric air indicating that in 19th century its average concentration was 335 ppmv (Figure 2). In Figure 2, encircled values show a biased selection of data used to demonstrate that in 19th century atmosphere the CO2 level was 292 ppmv. A study of stomatal frequency in fossil leaves from Holocene lake deposits in Denmark, showing that 9400 years ago CO2 atmospheric level was 333 ppmv, and 9600 years ago 348 ppmv, falsify the concept of stabilized and low CO2 air concentration until the advent of the industrial revolution. 
So what did the IPCC say about all this;
In the IPCC’s Climate Change 2001: Working Group I: The Scientific Basis you will find the following in chapter 3: “The Carbon Cycle…”:3.1: “
“The concentration of CO2 in the atmosphere has risen from close to 280 parts per million (ppm) in 1800, at first slowly and then progressively faster to a value of 367 ppm in 1999, echoing the increasing pace of global agricultural and industrial development. This is known from numerous, well-replicated measurements of the composition of air bubbles trapped in Antarctic ice. Atmospheric CO2 concentrations have been measured directly with high precision since 1957; these measurements agree with ice-core measurements, and show a continuation of the increasing trend up to the present.”
You may well ask why all those original data were ignored? Again, we need to dig a little into history. It was deemed by some that those records could not be trusted, as the measuring techniques, back in the day, were not of sufficient quality to warrant their inclusion. Strange then, looking at the chart, that some of those data in the mid-1800s were good enough, while others weren’t. Guess which ones weren’t deemed good enough?
Can the criticism of earlier techniques be justified? I’ll leave you to judge as there were 11 oft-used measuring techniques (gravimetric, titrimetric, volumetric and manometric) which had been evolved from 1812 to modern times, from which the so-called Pettenkofer method (titrimetric) was easy, fast and well understood and the optimized standard from 1857 for 100 years.
Accurate measurements had been done amongst others by de Saussure 1826, Pettenkofer/v.Gilm 1857, Schulze 1864/71, Farsky 1874, Uffelmann 1886, Letts und Blake 1897, Krogh and Haldane 1904, Benedict 1912, Lundegardh 1920, van Slyke 1929, Dürst and Kreutz 1934 alternatively 1940, Misra 1942 or Scholander 1946, with measuring instruments through which from 1857 (Pettenkofer) an accuracy of +/-0.0006 Vol% to under +/-0.0003 Vol% =~3 ppm (Lundegardh 1926) was achieved.
Mentioned authors had calibrated their methods against each other and samples with known content. All measuring parameters, local modalities and measuring errors can be extracted out of available literature.
They show precise seasonal and some diurnal variation. These pioneers of chemistry, biology, botany, medicine and physiology laid foundations for today’s knowledge of metabolism, nutrition science, biochemistry and ecology. Modern climatology ignored their work till today even though it is the basis of all textbooks of the mentioned faculties and was honoured with several Nobel prizes.
False Low Pre-industrial CO2 in the Atmosphere
Determinations of CO2 in polar ice cores are commonly used for estimations of the pre-industrial CO2 atmospheric levels. Perusal of these determinations convinced me that glaciological studies are not able to provide a reliable reconstruction of CO2 concentrations in the ancient atmosphere. This is because the ice cores do not fulfil the essential closed system criteria. One of them is a lack of liquid water in ice, which could dramatically change the chemical composition the air bubbles trapped between the ice crystals. This criterion, is not met, as even the coldest Antarctic ice (down to -73°C) contains liquid water. More than 20 physico-chemical processes, mostly related to the presence of liquid water, contribute to the alteration of the original chemical composition of the air inclusions in polar ice.
We can see, thus far, that certain key elements in the ongoing climate saga are open to debate. We have a) selective use of early measurements of atmospheric CO2 levels and b) reasonable doubt in the use of another metric – polar ice cores – as a way of confirming those pre-industrial levels. Even at this simplistic level of analysis it should be enough to ring alarm bells.
Finally, Just take the time to study these two images and ask yourself one question. Why have I never seen or heard of this stuff before?
Where do we stand now? Who were the driving forces behind the move to ignore all those old data? To be continued . . .