Our study shows that organic carbon burial during the Eocene was an order of magnitude lower than modern. In contrast, the measured Bio-Ba flux, a proxy for primary productivity and organic carbon rain and sedimentation, was greater than or equal to modern rates throughout the Eocene. This discrepancy between the observed and expected Corg flux suggests that a higher rate of organic carbon remineralization occurred in the upper water column or at the sediment/water interface during the Eocene. Higher utilization of Corg would be expected on the basis of thermodynamic considerations alone and is predicted by the UTD Theory by Gilooly et al. (2001) and new data from the field of ecology (e.g., Clarke and Fraser, 2004). Higher metabolic rates, and concomitant increased demand for carbon and all nutrients, would have resulted directly from the 10°–12°C increase in ocean temperatures for the Eocene equatorial Pacific Ocean relative to modern conditions. We propose that organic carbon burial was "short-circuited" via remineralization and reutilization by all organisms. This proposed mechanism, combined with our data, is consistent with the evidence that the Calcite Compensation Depth was much shallower, and atmospheric CO2 was much higher, during the Eocene.
Finally, our understanding of the global organic carbon cycle throughout geologic time requires a fundamental recognition that what we measure in the sediments (the component that is preserved) may not be modeled simply as the remainder that is left behind after the sum of processes has remineralized buried organic carbon. This shortcoming in our thinking is succinctly stated by Hedges and Keil (1995) and quoted here as we proceed to elucidate the geologic record of Earth's dynamic history: "it is useful to note that degradation of organic matter and its preservation in marine sediments are often treated equivalently, many times with the assumption that the selectivity and extents of early diagenesis will be informative of preservation potential. Degradation and preservation, however, are opposite processes and information on organic matter mineralization is not necessarily useful for understanding preservation."