The Mid-Cretaceous Super Plume, Carbon Dioxide, and Global Warming
Ken Caldeira & Michael R. Rampino
An investigation of the effects that a mid-cretaceous super plume could have had on atmospheric CO2 concentration at the time, and how this would have contributed to global warming. It is concluded that the super plume would have created CO2 concentrations that would induce warming up 7 to 12 degrees centigrade when combined with paleogeographic effects.
Carbon-dioxide releases associated with a mid-Cretaceous super plume and the emplacement of the Ontong-Java Plateau have been suggested as a principal cause of the mid-Cretaceous global warming. We developed a carbonate-silicate cycle model to quantify the possible climatic effects of these CO2 releases, utilizing four different formulations for the rate of silicate-rock weathering as a function of atmospheric CO2. We find that CO2 emissions resulting from super-plume tectonics could have produced atmospheric CO2 levels from 3.7 to 14.7 times the modern pre-industrial value of 285 ppm. Based on the temperature sensitivity to CO2 increases used in the weathering-rate formulations, this would cause a global warming of from 2.8 to 7.7 degrees centigrade over today's global mean temperature. Altered continental positions and higher sea level may have been contributed about 4.8 degrees to mid-Creataceous warming. Thus, the combined effects of paleogeographic changes and super-plume related CO2 emissions could be in the range of 7.6 to 12.5 degrees, within the 6 to 14 degree range previously estimated for mid-Cretaceous warming. CO2 releases from oceanic plateaus alone are unlikely to have been directly responsible for more than 20% of the mid-Cretaceous increase in atmospheric CO2.