Evaluation of atmospheric carbon dioxide concentrations during the Cretaceous

Studying the role of atmospheric carbon dioxide concentration (pCO(2)) regulating temperature during the Cretaceous is important to understand the evolution of the Cretaceous climate. However, the pCO(2) variation during the Cretaceous remains uncertain. Here we present a new paleo-pCO(2) variation record spanning the Barremian to Maastrichtian time. The new paleo-pCO2 calculations are based on analyses of pedogenic carbonate from the Gyeongsang Basin, Korea and data from the literature on pedogenic carbonates. Our results show that the mid-Cretaceous pCO(2) levels were higher than those observed during the Early and the Late cretaceous, and that the highest pCO(2) was achieved between the Cenomanian and the Turonian. This pCO(2) trend is in agreement with the paleotemperature records. Our results also show that three intervals of low pCO(2) (<400 ppmV) in the Early and the Late Cretaceous seem to be associated with climatic changes suggestive of glacial episodes. These results suggest that the Cretaceous climatic change was associated with pCO(2) variations. Variations in the rate of outgassing caused by variations of oceanic crust production rate have been known as a major cause of the mid-Cretaceous warmth. However, our results show the discrepancy in the timing between the highest rate of oceanic crust production and the highest pCO(2) levels during the mid-Cretaceous. We interpret that large subaerial volcanisms in the Caribbean and Madagascar Large Igneous Provinces were instrumental for providing additional CO2 to the atmosphere, resulting in the warmest mid-Cretaceous. (C) 2012 Elsevier E.V. All rights reserved.