pCO 2 over this period although there are large offsets in absolute values and magnitudes of the trends between different sites( note the variable vertical scales on these graphs). A small number of the very highest values at some sites exceed 400 ppm( note colour bands express uncertainty). This was the paper referred to in the Scripps commentary( http:// keelingcurve. ucsd. edu / what-does-400-ppm-looklike /).
vi Seki et al.( 2010)
Fig. 6. Previous records( panel a) and new data( panels b and c) for the last 5 million years compared to the oxygen isotope stack from Seki et al.( 2010). Red lines added.