Moderate to Elevated Atmospheric CO ₂ During the Early Paleocene Recorded by <i>Platanites</i> Leaves of the San Juan Basin, New Mexico

Throughout the Phanerozoic, estimated CO2 levels from proxies generally correlate well with independent estimates of temperature. However, some proxy atmospheric during Late Cretaceous and early Paleocene are low (<400 ppm), seemingly at odds elevated sea surface Here we evaluate by applying a leaf gas-exchange model to Platanites leaves four localities San Juan Basin, New Mexico (65.66–64.59 Ma). We first calibrate on two modern Platanus species, occidentalis P. × acerifolia, where find accurately predicts present-day CO2, mean error rate between 5% 14%. Applying Paleocene, varies ∼660 1,140 ppm. These consistent more recent boron, gas-exchange, liverwort, paleosol that all suggest moderate Paleocene. in keeping temperature this period.