CARBON DIOXIDE LEADS TEMPERATURE?
By Dr Vincent Gray
It is a persistent claim by the IPCC and its supporters that since carbon dioxide is the cause of global warming its increase in concentration before any increase in temperature should be apparent in “proxy” measurements of both these quantities from past geological ages.
The current evidence is equivocal because of the low accuracy of the measurements, but, as has been recently shown by Joanne Nova , the Vostok and Law Dome ice cores show that the temperature rises before the atmospheric carbon dioxide concentration for most of the past 42,000 years.
A recent paper claims the reverse: that CO2 change precedes temperature change:
“Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Jeremy D. Shakun, Peter U. Clark, Feng He, Shaun A. Marcott, Alan C. Mix, Zhengyu Liu, Bette Otto-Bliesner, Andreas Schmittner & Edouard Bard Nature 484,49–54 (05 April 2012) doi:10.1038/nature10915”
There is currently no evidence that increased human-based emissions of carbon dioxide or other “greenhouse gases” have any measurable effect on the climate. This view is based upon my experience as an expert reviewer of all of the Reports of the Intergovernmental Panel on Climate and an intimate knowledge of everything in them.
The climate is such a complex system that any system which purports to understand it has to prove that it can forecast future climate over the whole range for which it is considered suitable, to a satisfactory level of accuracy, before it can be accepted. This exercise has never been made, let alone established as valid for the “Greenhouse” theory, so it should be ignored.
The claims of the IPCC Reports are based on estimates of various levels of “likelihood” that model “projections” are possibly true by the authors themselves. These estimates are not only entirely subjective, but they are also made by those paid to supply the models, and are therefore compromised by conflict of interest. The numerical levels of “significance” attached to these estimates have no basis in a scientific statistical study.
The assertion that “the earth is warming” is also without scientific basis, since it is impossible to measure the average temperature of the earth’s surface. The “Mean Global Surface Temperature Anomaly Record” is so riddled with statistical errors that their realistic assessment would render any supposed “trend” to have an extremely low significance.
Much is made by the IPCC of the supposition that correlation, however unconvincing, is evidence of causation; in defiance of the ancient Greek logical maxim. To conceal this solecism they change the word “correlation” to “attribution”.
In the abstract to the above paper the authors seem reluctant to perjure themselves by denying the validity of such an ancient logical certainty, so they go only so far as to “suggest” “a close link” “between CO2 and climate during the Pleistocene ice ages”. This opinion is supported by a compilation of 80 Globally distributed “proxy” measurements made by a variety of methods.
However, the title of the paper claims that this “suggestion” is a proven fact
The abstract also claims that “the temperature is correlated with and generally lags CO2 during the last (that is the most recent) deglaciation.”
So, how good is the correlation and how “general” is the lag of temperature behind CO2?
The authors claim that recent amendments to the ice core measurements show a definite lag between carbon dioxide and temperature (their Figure 2a. top graph)
The Antarctic Ice Core Temperature record apparently now shows a very high correlation (r2 = 0.94) with the CO2 concentration when plotted (Figure 2a above) over the past 22,000 years. Each graph shows the same step function in the middle. There is a lag of temperature behind CO2 of 1,000 to 5000 years between 17,000 and 13,000 years ago.
This graph is very puzzling as the theory does not predict a linear correlation between carbon dioxide and temperature. The “global warming” models claim that temperature is determined by the logarithm of the carbon dioxide concentration. A linear correlation is incompatible with the models. Nobody would try to claim a correlation between even a lagged carbon dioxide concentration and the Mean Global Surface Temperature Anomaly Record, quite apart from the fact that even correlation with the logarithm of carbon dioxide concentration is not impressive and seems to have broken down altogether for the past ten years or so when the surface temperature anomaly has been approximately unchanged.
The Second graph (Figure 2b, the second graph) plots the extent of the lag of temperature behind CO2 against the length of the lag over 20,000 and 10,000 years and shows that in the Southern Hemisphere the lag is in the opposite direction, namely CO2 lags temperature. The lag of temperature against CO2 happens only in the Northern Hemisphere, and there seems to be a generally smaller lag in the opposite direction in the Southern Hemisphere.
BUT the small print in the caption beneath the graph states that the confidence intervals given are one standard deviation about the mean. It has been conventional in the statistical and the scientific literature to use two standard deviations for confidence limits, which give the 95% limits in which the true figure may lie. The use of limits of only one standard deviation is a device frequently used by the IPCC and its supporters to give a spurious impression of accuracy, as it includes only 68% of the possible range of the true figure
In this case, for the Globe, the figure 460±340 means that there is a 16% chance that the true figure may be less than 120 and a 2.5% chance that the figure may be less than -220.
For the Southern Hemisphere the figure is -620±660, which means there ia a 16% chance that it is greater than +40 and a 2.5% chance in that it may be greater than +700. For the Northern Hemisphere the figure is 720±330, which means that there is a 16% chance in that the figure may be less than+390 and a 2.5% chance that it may be less than -60
These figures apply only when there is a large number of all the samples and they all fit the normal curve closely. Any deviation from these requirements means that the chance that the two sets of figures are not significantly different increases.
The study claims to give a global cover. The location of the samples is shown in Figure 1
They appear to show a balanced coverage between the Northern and Southern Hemispheres, but otherwise the sample is grossly unrepresentative of the earth’s surface. The only places that are firmly on land are those in Antarctica. Only three or four are from the ocean and the rest appear to be from coastal sites. The apparent difference between the Northern and Southern Hemispheres may merely be a reflection of this gross sampling deficiency.
The many inaccuracies involved in all of the measurements, combined with the poor sampling and the evident attempt to cover them up by quoting misleading confidence limits leads inevitably to the conclusion that this paper has failed to show a genuine global lag between carbon dioxide and temperature over the Pleistocene, in either direction to a significant degree of accuracy.