Figure 3. Comparison of the ice-core CO₂ record of Barnola et al. (1987) with surface-water pCO₂ estimates for Geosciences Bremen (GeoB) Core 1016-3, using the conversion for δ¹³C of organic matter to CO₂ pressure proposed by Popp et al. (1989) and Rau et al. (1991; eq. = equation). Time scale of Vostok ice core is adjusted for best fit. Hatched pattern = misfit (from Müller et al., 1994).