Paleoclimate modeling: an integrated component of climate change science

Past climates provide an opportunity to examine the working of the Earth system under a much wider range of forcing than those experienced during the historical period. The Paleoclimate Modelling Intercomparison Project (PMIP) is an ongoing program tasked with the systematic comparison of models and observations of past climate. Over the last 20 years, through the definition of model experimental designs and the syntheses of paleoenvironmental data, PMIP has made significant progress in the understanding of a number of key periods of the past. Previous PMIP experiments have included the mid-Holocene (MH) and the Last Glacial Maximum (LGM). For the latest iteration, PMIP3, the last millennium (LM), the Eemian (last interglaciation) and the mid-Pliocene warm period (approximately three million years ago) have been added. Three of these PMIP3 experiments (MH, LGM, LM) have been included as high-priority simulations in the Coupled Model Intercomparison Project (CMIP5; Taylor et al. 2012), which provides the framework for coordinated climate change experiments used in the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5).