Figure 3.2: Variations in
atmospheric CO2 concentration on different time-scales. (a) Direct
measurements of atmospheric CO2 concentration (Keeling and Whorf, 2000),
and O2 from 1990 onwards (Battle et al., 2000). O2 concentration
is expressed as the change from an arbitrary standard. (b) CO2 concentration
in Antarctic ice cores for the past millenium (Siegenthaler et al., 1988; Neftel
et al., 1994; Barnola et al., 1995; Etheridge et al., 1996). Recent atmospheric
measurements at Mauna Loa (Keeling and Whorf, 2000) are shown for comparison.
(c) CO2 concentration in the Taylor Dome Antarctic ice core (Indermühle
et al., 1999). (d) CO2 concentration in the Vostok Antarctic ice core
(Petit et al., 1999; Fischer et al., 1999). (e) Geochemically inferred CO2
concentrations, from Pagani et al. (1999a) and Pearson and Palmer (2000). (f)
Geochemically inferred CO2 concentrations: coloured bars represent
different published studies cited by Berner (1997). The data from Pearson and
Palmer (2000) are shown by a black line. (BP = before present.)
