Reference
Indermuhle, A., Monnin, E., Stauffer, B. and Stocker, T.F. 2000. Atmospheric CO2 concentration from 60 to 20 kyr BP from the Taylor Dome ice core, Antarctica. Geophysical Research Letters 27: 735-738.
What was done
The authors obtained a high-resolution record of atmospheric CO2 concentration spanning the period from 60 to 20 thousand years before present from the Antarctic Taylor Dome ice core, after which they compared this CO2 history with a temperature history obtained from the Antarctic Vostok ice core.
What was learned
Over the period of record, there were four distinct spikes in both the atmospheric CO2 concentration and air temperature histories, with temperature rising by approximately 2°C and CO2 concentration rising by about 20 ppm. One type of statistical test performed on the data by the authors suggested that the shifts in the air's CO2 content lagged those in the air's temperature by approximately 900 years. A second statistical test yielded a mean lag time of 1200 years; while a third such test, performed by Fischer et al. (1999) on data pertaining to early deglacial changes in the last three glacial-interglacial transitions, yielded a mean lag time of 600 years.
What it means
As we have long contended - see the various reports filed under Carbon Dioxide (Correlations with Temperature) in our Subject Index - these results continue to demonstrate that atmospheric temperature is the independent variable or leader of this dynamic geophysical duo, while atmospheric CO2 concentration is the dependent variable or follower. Logic, pure and undefiled, absolutely demands that cause must precede effect.
How much more clear can it be? Increases (decreases) in air temperature drive increases (decreases) in atmospheric CO2 concentration, and not vice versa. Hence, it is not rational to claim, as climate alarmists always do, that the weak correlation between global mean air temperature and atmospheric CO2 concentration that exists over parts of the last century is evidence that the historical increase in this minute trace gas of earth's atmosphere is the cause of the intermittently observed warming that has sometimes occurred over this period. It is much more likely that, if anything, just the opposite is true.
