We begin this task with our analysis of the study of Kirchner (2002), who constructed a pair of graphs that depict TA as linear functions of the air's CO2 and methane concentrations based on 400,000 years of pertinent data derived from the Vostok ice core. These plots indicate, in his words, that "despite greenhouse gas concentrations that are unprecedented in recent earth history, global temperatures have not risen nearly as much as the correlations in the ice core records would indicate that they could." In fact, he says that "for the current composition of the atmosphere, current temperatures are anomalously cool by many degrees."

So, just how "anomalously cool" is the planet's current temperature? Kirchner's TA vs. CO2 plot suggests that the earth is currently about 10°C too cool, while his TA vs. CH4 plot - which is by far the better defined and more robust of the two relationships - suggests that the globe is fully 40°C too cool. Consequently, these observationally-based relationships provide absolutely no basis for characterizing earth's current temperature as anomalously high, as the world's climate alarmists always do. Rather, it is the air's CH4 and CO2 concentrations that are currently "anomalously high," with earth's temperature sitting squarely in the normal range.

What is the take-home message of these observations? We suggest they imply that TA must be the determinant of atmospheric CH4 concentration, and not vice versa, as long as humanity is not a part of the picture. For nearly all of the past 400,000 years, this latter condition has applied; and the TA vs. CH4 relationship derived by Kirchner has never been violated. As mankind's numbers and their impact on the atmosphere's trace gas concentrations have skyrocketed over the past few centuries, however, the planet has clearly outgrown this relationship; and the atmosphere's CH4 concentration has risen to levels far above anything experienced over the entire history of the Vostok ice core. What is more, it has done so without any significant impact on global air temperature; and the same would appear to hold true for CO2, although the scatter in Kirchner's temperature vs. CO2 plot is sufficient to allow for significant independent movement by both of these parameters.

Additional light has been shed on the subject by two reports that provide CO2, methane and temperature data stretching a full 650,000 years back in time (Siegenthaler et al., 2005; Spahni et al., 2005), based on measurements made on East Antarctica's Dome Concordia ice core, which was originally extracted and cursorily analyzed by Augustin et al. (2004), as described in our Editorials of 30 Nov 2005 and 7 Dec 2005. These data indicate that the atmosphere's current CO2 concentration is about 30% higher than it was at any other time over the last 650,000 years, and that the air's current methane concentration is 130% higher, which high concentrations have been described as "geologically incredible." Hence, if the world's climate alarmists are correct about the tremendous warming power they attribute to these two top greenhouse gases, one would logically expect the earth to be currently experiencing some incredibly high air temperatures. So what do the ice core data indicate in this regard?

Both the Dome Concordia and Vostok data sets suggest that the peak temperature of the current interglacial or Holocene was not incredibly higher than the peak temperatures of all of the past four interglacials, the earliest of which is believed to have been nearly identical to the Holocene in terms of earth's orbit around the sun. In fact, the Holocene's peak temperature was not higher than those of the preceding four interglacials by even a tiny fraction of a degree. In fact, it was lower. In fact, the work of Petit et al. (1999) revealed that the peak temperature of the Holocene was more than 2°C lower than the average peak temperature of the prior four interglacials. What is more, earth's current temperature is lower still.

In light of these several real-world observations, we are forced to conclude that if there is anything unusual or unnatural or unprecedented about earth's current air temperature compared to the temperatures of prior interglacials, it is that it is so much colder now in spite of there being so much more CO2 and methane in the air. Clearly, therefore, earth's climate system does not operate the way the world's climate alarmists claim it does.

References
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Kirchner, J.W. 2002. The Gaia Hypothesis: fact, theory, and wishful thinking. Climatic Change 52: 391-408.

Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M.., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pepin, L., Ritz, C., Saltzman, E. and Stievenard, M. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399: 429-436.

Siegenthaler, U., Stocker, T., Monnin, E., Luthi, D., Schwander, J., Stauffer, B., Raynaud, D., Barnola, J.-M., Fischer, H., Masson-Delmotte, V. and Jouzel, J. 2005. Stable carbon cycle-climate relationship during the late Pleistocene. Science 310: 1313-1317.

Spahni, R., Chappellaz, J., Stocker, T.F., Loulergue, L., Hausammann, G., Kawamura, K., Fluckiger, J., Schwander, J., Raynaud, D., Masson-Delmotte, V. and Jouzel, J. 2005. Atmospheric methane and nitrous oxide of the late Pleistocene from Antarctic ice cores. Science 310: 1317-1321.