consistent inter-species offsets and reconstructions of pH versus depth( Pearson and Palmer 1999) which would not have been possible if we were not roughly in the right ballpark, so to speak. We were also able to reconstruct glacial to interglacial changes in pCO 2 with good quantitative accuracy using the same technique( Palmer and Pearson 2003). Clearly, however, the record needs replacing by newer and better data and some contributions toward that are considered below.
ii. Pagani et al.( 1999 and 2005)
Fig. 2. Record of Pagani et al.( 2005) from alkenones from 0-50 Ma. Note there are no data from the last 5 m. yr. Red line added.
The record of Pagani et al.( 2005)( the Miocene part of which is from Pagani et al. 1999) utilises the alkenone proxy. It can be seen from this record that the last time there were values > 400 ppm was in the Oligocene epoch( or just maybe in the early Miocene). There have been some recent revisions and additions to this data set since, for example, attempts to account for cell size effects, to deal with areas of high productivity, and to provide better estimates of temperature. However in general the record is similar to Pearson and Palmer( 2000) in showing the relatively low pCO 2 values from the Miocene onward( which is, incidentally, something neither research group expected to find when the work started).