... "transitions from glacial to interglacial conditions are relatively sharp, while the ice ages themselves are punctuated by smaller warming and cooling episodes.
... though it’s hardly visible in the figure, the ice-age CO2 level closely mimics changes in temperature,
but the CO2 concentration lags behind – with CO2 going up or down after the corresponding temperature shift occurs.
The lag is about 600 to 800 years.
Most paleoclimatologists believe that CO2 lagged temperature during the ice ages
because it takes several hundred years for CO2 to come out of, or get into, the world’s oceans,
which is where the bulk of the CO2 on our planet is stored.
The oceans can hold much more CO2 (and heat) than the atmosphere.
Warm water holds less CO2 than cooler water, so the oceans release CO2 when the temperature rises, but take it in when the earth cools.
Richet noticed that the temperature peaks in the Vostok record are much narrower than the corresponding CO2 peaks.
but from 14,000 to 23,000 years for the initial CO2 peak;
cycle V can’t be analyzed because its start is missing from the data.
All other peaks are also narrower for temperature than for CO2.
The author argues that CO2 can’t drive temperature since an effect can’t last for a shorter period of time than its cause.
The fact that the peaks are systematically wider for CO2 than for temperature implies that the CO2 level responds to temperature changes, not the other way round.
And for most of cycles II, III and IV, CO2 increases correspond to temperature decreases and vice versa.
Richet’s conclusion, if correct, would deal a deathblow to the CO2 global warming hypothesis.
The reason has to do with the behavior of the temperature and CO2 level at the commencement and termination of ice ages.
Ice ages are believed to have ended (and begun) because of changes in the Earth’s orbit around the sun.
After tens of thousands of years of bitter cold, the temperature suddenly took an upward turn.
But according to the CO2 hypothesis, the melting of ice sheets and glaciers caused by the slight initial warming could not have continued,
unless this temperature rise was amplified by positive feedbacks.
These include CO2 feedback, triggered by a surge in atmospheric CO2 as it escaped from the oceans.
The problem with this explanation is that it requires a similar chain of events, based on CO2 and other feedbacks, to have enhanced global cooling as the temperature fell at the beginning of an ice age.
But, says Richet, “From the dual way in which feedback would work, temperature decreases and increases should be similar for the same concentrations of greenhouse gases, regardless of the residence times of these gases in the atmosphere.”
The fact that temperature decreases don’t depend in any noticeable way on CO2 concentration in the figure above demonstrates that the synchronicity required by the feedback mechanism is absent."