On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures
We present results from our investigation into the physical mechanisms through which the mid-Pliocene, with a p CO2 of only ∼400 ppmv, could have supported the same magnitude of global warmth as has been projected for the climate at the end of the 21st century when p CO2 is expected to be 3 times higher. These mechanisms allow us to understand the warming in terms of changes to the radiative properties of the surface, the clouds, greenhouse gases, and changes to the meridional heat transport. We find that two-thirds of the warming pervasive during the mid-Pliocene, compared to the preindustrial, could be attributed to the reduction in the planetary emissivity owing to the higher concentrations of the greenhouse gases CO2 and water vapor, and the remaining one-third to the reduction in planetary albedo. We also find that changes to the orography and the p CO2 are the leading causes of the warming with each contributing in roughly equal parts to a total of 87% of the warming and changes to the polar ice sheets responsible for the remaining warming.
Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S1A7, Canada
Recommended Citation:
Chandan D.,Richard Peltier W.. On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures[J]. Climate of the Past,2018-01-01,14(6)