SENSITIVITY OF THE LATE PERMIAN-EARLY TRIASSIC CLIMATE TO ATMOSPHERIC CO2 CONCENTRATIONS AND THE IMPLICATIONS FOR THE MASS EXTINCTION

The largest mass extinction during the Phanerozoic Eon occurred near the Permian-Triassic boundary (ca. 252 Ma). The loss of biodiversity within the terrestrial and marine realms coincided with the eruption of the Siberian Flood Basalts, leading to the emission of greenhouse gases into the atmosphere. Significant carbon isotope shifts indicate that perturbations in the carbon cycle occurred during the Late Permian and persisted into the Early Triassic.

In this study, we assess the climatic changes across the Permian-Triassic boundary by evaluating output from the Climate Community System Model Version 3 with climate proxies. Results from several model experiments with various concentrations of atmospheric pCO₂ are compared with maps of phytogeographic patterns and climate-sensitive sediments in order to better understand the environmental changes that occurred during the Late Permian-Early Triassic transition. The analysis of climate simulation results suggests an expansion of tropical and temperate regions within the oceans along with a complete elimination of cold temperate (below 0º C) conditions. On the supercontinent of Pangea, an expansion of deserts within the inner continent and an increase of tropical climates near the equator are inferred from shifts in biomes. Extreme temperature increases coupled with changing precipitation patterns likely contributed to the mass extinction of much of the fauna and flora as suggested by the modeling results and phytogeographic patterns.