Modelling the Pliocene using the Earth System model HadGEM2-ES

The mid Pliocene Warm Period (3.29-2.97Ma) has been the subject of much modelling effort in recent years. Studying this period provides an effective way to understand the mechanisms and processes that operate in a warm climate which are of potential relevance to future climate change. This period can also be used as an important test of climate models that are used to predict future climate. Due to the high computational cost, the latest, state-of-the-art Earth system models (ESM's), used in the most advanced predictions of future climate change have not been run for the Pliocene climate. However, these models are the most important for validating against different climates and can provide extra information about processes operating in those climates (eg. chemistry, dust, methane emissions) that are not included in standard coupled atmosphere-ocean General Circulation Models (GCM's). It is important to note that many climate models used in the palaeo-community are no longer used in future climate change assessments. Thus the palaeo-climate community must move forward and utilize state-of-the-art ESM's whenever possible. Here we present early results of the first simulations of the mid Pliocene Warm Period (mPWP) using the atmosphere only version of the Hadley Centre ESM, HadGEM2-ES. These early results are encouraging and suggest that both the temperature and precipitation anomalies, between the mPWP and the pre-industrial, are larger in HadGEM2-ES than in a previous version of the Hadley Centre model, HadCM3. The temperature and precipitation changes are also largest at high northern latitudes showing a greater degree of polar amplification in HadGEM2-ES.