Carbon dioxide emissions from Deccan Volcanism and a K/T boundary Greenhouse Effect

A greenhouse warming caused by increased emissions of carbon dioxide from the Deccan Traps volcanism has been suggested as the cause of the terminal Cretaceous extinctions on land and in the sea. We estimate total eruptive and noneruptive CO₂ output by the Deccan eruptions (from 6 to 20 × 10¹⁶ moles) over a period of several hundred thousand years based on best estimates of the CO₂ weight fraction of the original basalts and basaltic melts, the fraction of CO₂ degassed, and the volume of the Deccan Traps eruptions. Results of a model designed to estimate the effects of increased CO₂ on climate and ocean chemistry suggest that increases in atmospheric pCO₂ due to Deccan Traps CO₂ emissions would have been less than 75 ppm, leading to a predicted global warming of less than 1°C over several hundred thousand years. We conclude that the direct climate effects of CO₂ emissions from the Deccan eruptions would have been too weak to be an important factor in the end‐Cretaceous mass extinctions.