REVISITING EARLY PERMIAN CO2 VIA IMPROVED INPUT PARAMETERS AND MODELS

The late Paleozoic Ice Age (LPIA; 340–290 Ma) archives repeated major climate changes within an icehouse and is the only record of a permanent turnover from icehouse to fully greenhouse conditions since the evolution of metazoans and vascular plants. In addition, the LPIA has long been compared to the Pleistocene glacial state given that both were characterized by very low atmospheric pCO₂, eccentricity-scale glacial-interglacial cycles, and extensive, long-lived continental ice sheets. Existing paleoatmospheric CO₂ estimates, based on paleosol carbonates and fossil plant proxy methods, show a linkage between shifts in pCO₂, ice volume, and climate that are indicative of greenhouse gas-forcing. Here, focusing on the demise of the LPIA, we reevaluate published latest Pennsylvanian through middle Permian CO₂ estimates by applying existing paleosol carbonate data and an improved organic matter data set to the PBUQ model, which fully propagates the uncertainty associated with all input parameters. The updated CO₂ estimates are directly compared to plant-based early Permian CO₂ values obtained using a mechanistic CO₂ model and fossil cuticles collected from the same stratigraphic successions as the pedogenic carbonates. Preliminary reformulated Early Permian CO₂ results indicate absolute pCO₂ estimates are more than half those previously published (Montañez et al. 2007), and delineate a CO₂ rise from a Late Pennsylvanian-earliest Permian nadir to a mid-Permian maximum of ~1400 ppm. In addition, there is good agreement between paleosol-based and stomata-based mechanistic CO₂ estimates. These improved data represent an opportunity to understand the evolution of CO₂ during the demise of global glaciation, with implications for our current glacial state.