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 .