First, the figure gives the answer on CO2 and temperature over
the last 800,000 years: Here we have each value of CO2 plotted
against the temperature deviation from reference values -- with
the temperature being for 1000 years before the corresponding
CO2 value. The correlation for this is about 0.89 (R), meaning
that you could explain 79 percent (0.89*0.89) of the variation
(R^2) in CO2 by looking at the temperature. As is mentioned in
my post Does CO2 correlate with temperatures, where we saw
equally high correlation between temperature and CO2 (even
higher if you give CO2 a 20-30 year lead on temperature), and
quite a few times in the comments, correlation is not causation.
Could be that both temperature and CO2 are pushed around by
something else. More about that in a moment. It's common to see
the claim that temperature 'leads' CO2. Loosely speaking, this
means that temperatures generally change before CO2 does, and
that there is a consistent pattern to the connection -- if
temperature rises, CO2 does as