Multiple Permian-Triassic life crises on land and at sea

The largest mass extinction in the history of life was during the Late Permian, ca 252 Ma. New evidence from stable isotopic composition and Bk metrics of paleosols from the Late Permian to the Middle Triassic in the southern Karoo Basin of South Africa, reveal at least four atmospheric carbon dioxide spikes, coinciding with extinctions on land and at sea. The Karoo Basin was mainly arid throughout this interval, but the four life crises correlate with extreme greenhouse spikes of carbon dioxide and transient episodes of warmer and more humid climate, with respiratory distress for vertebrates and roots of wetland plants. These most extreme greenhouse crises in the history of life provide worst-case scenarios for modern global climate change.