Palaeo perspectives on climate extremes: What can the Pliocene tell us?

The Pliocene Model Intercomparison Project (PlioMIP; phases 1 and 2) has provided a wealth of model output relating to a climate with CO₂ ~400ppmv.  However much of the analysis of this dataset has focussed on temporally averaged diagnostics. 

Here we look at the contribution of the HadCM3 model to PlioMIP2 in more detail.  We consider daily precipitation, the maximum daily temperature, and the minimum daily temperature, and use these to derive indices of extreme weather and climate.    

We show that the area of land where the maximum daily temperature exceeds 40^oC at some point during the year was greatly expanded in the Pliocene compared to the preindustrial.  We also show that, at many locations, most days in the year have daily temperatures that are above the warm extreme threshold for that calendar day in the preindustrial.  Correspondingly very few Pliocene temperatures are below the preindustrial cold extreme threshold.

These Pliocene extreme climate diagnostics can be compared with future extreme climate diagnostics to provide additional information about the analogous nature of the Pliocene climate.