Long description

Two graphs of data from the EPICA ice core. The top panel is identical to the figure described in Figure 13, that is the temperature change inferred from the ice core over the last 800 000 years BP. The bottom panel shows how the atmospheric carbon dioxide trapped in the ice core varies over the same time period as the top panel. The two plots appear correlated, with warm temperature changes occurring at the same time as high atmospheric CO₂ concentrations of typically around 280 ppm, and the cold periods occurring at the same time as low atmospheric CO₂ concentrations of typically about 180 ppm. In a similar way to that described for Figure 13, the amplitude of the variation in atmospheric CO₂ concentrations reduces in periods earlier than 450 000 years BP. The warm periods then have a maximum atmospheric CO₂ concentration of typically 20 ppm less at around 260 ppm whilst the minimum is similar at about 180 ppm.