What caused the atmosphere's CO2 content to rise during the last 8000 years?

We make a case that the 20 ppm rise in atmospheric CO 2 content over the last 8000 years was at least in part a consequence of the 500 Gt C increase in terrestrial biomass early in the present interglacial rather than of a 200 Gt C decrease in terrestrial biomass during the latter part of the Holocene as proposed by Indermühle et al. 1999. In support of this claim, we present new 13 C measurements from an Ontong Java Plateau box core, which do not reproduce the trend deduced from measurements on CO 2 from the Taylor Dome ice core. In attempt to distinguish between scenarios put forth to accounting for the late Holocene rise in atmospheric CO 2 content, we also made foraminifera shell weight measurements on three box cores from the Ontong Java Plateau. We were surprised to find that the early Holocene CaCO 3 preservation event we sought was strongly depth dependent. The largest magnitude was at 4 km where CO 3 = ion concentrations appear to have been 30 μmol/kg higher than today's and hence nearly as high as those in today's North Atlantic Deep Water.