coloured bands in the background. A strength of this record is that it matches well with the glacialinterglacial variability seen in the ice cores( the grey curve confined to the first million years). A small number of data points exceed 400 ppm but most are in the range 200-350 ppm. Like many of the other records, there appears to be a declining trend over the 5 m. yr period. Note that the data were obtained by TIMS and are offset from the values measured in the same species by Seki et al.( 2010) so the two data sets are not directly comparable.
viii. Pagani et al.( 2011)
Fig. 8. Alkenone pCO 2 reconstructions( colours) against oxygen isotope stack( grey) from Pagani et al.( 2011) for the period 20 – 45 Ma. Red line added.
This study spans the Eocene / Oligocene transition( like Pearson et al. 2009) but covers a much wider range of ages. Various data sets from high latitude settings were excluded for reasons discussed in the paper. All the estimates > 26 Ma are above 400 ppm, only the four points from 20-26 are all below this value.