What does the Vostok ice core tell us?

Euan Mearns, who runs a blog called Energy Matters, had a post in 2014 about The Vostok ice core: Temperature CO2 and CH4.

This post has apparently had 8000 reads, is probably one of the most read texts on the subject, and yet, according to this post,

the Climate Science community continues to ignore the fairly profound implications of what the data actually shows.

The key issue appears to be a lag between temperature changes and CO2/CH4 changes that led Eaun to conclude that

variations in CO2 and CH4 are both caused by global temperature change and freeze thaw cycles at high latitudes.

These natural geochemical cycles makes it inevitable that CO2 and CH4 will correlate with temperature.

It is therefore TOTALLY INVALID to use this relationship as evidence for CO2 forcing of climate,

especially since during the onset of glaciations, there is NO correlation AT ALL.

It is certainly NOT the case that CO2 is the main driver of the glacial cycles.

The trigger for the glacial cycles is probably orbital variations, in particular large changes in solar insolation at high northern latitudes. However, the net change in solar insolation (globally) is small, so it cannot – by itself – produce much in the way of warming/cooling.