Uniformitarian Prediction of Early‐Pleistocene Atmospheric CO2

Abstract

AbstractDespite recent empirical and modeling advances, atmospheric CO2 concentrations during the early Pleistocene remain uncertain. Using a recently‐developed Bayesian paleoclimate model, an ensemble of seven different CO2 records is inferred conditional on reconstructions of past sea level. Five ensemble members give a consensus prediction that CO2 concentrations averaged 241 ppm (238–245 ppm 95% CI) between 2 and 0.8 Ma. Uncertainty estimates account for contributions from orbital forcing, age uncertainties, and other factors. Our consensus prediction aligns well with a compilation of previously published δ11B‐based CO2 reconstructions after calibration to late‐Pleistocene ice‐core CO2 values, as well as with 60 early‐Pleistocene CO2 measurements from the Allan Hills in East Antarctica. Our consensus prediction can be definitively tested by obtaining continuous ice‐core atmospheric CO2 records that extend into the early Pleistocene.