Using paleo-climate model/data comparisons to constrain future projections

For the first time in climate modeling history, there is a substantial component of coordinated paleoclimate modeling being performed with the same models and with the same protocols as the projections of future climate change. We have heard for many years the claim that understanding paleo-climate is the key to understanding future potential changes, and indeed, much work has already been done (via PMIP 1 and 2, and many individual studies). However, these has been a lack of quantitative analysis that truly links the future simulations or forecasts with skill or sensitivity in the paleo-climate simulations, most often because paleo-simulations were not done with the same models currently being used for future projections and through a lack of suitable paleo-climate skill metrics.