Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) – experimental design

A M Dolan,A M Haywood,S J Koenig,D J Hill,R M Deconto

doi:10.5194/gmd-5-963-2012

A M Dolan, A M Haywood + Show 3 more

Open Access

https://doi.org/10.5194/gmd-5-963-2012

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Abstract

Abstract. During the mid-Pliocene warm period (3.264 to 3.025 million years ago), global mean temperature was similar to that predicted for the next century and atmospheric carbon dioxide concentrations were slightly higher than today. Sea level was also higher than today, implying a reduction in the extent of the ice sheets. Thus, the mid-Pliocene warm period (mPWP) provides a unique testing ground to investigate the stability of the Earth's ice sheets and their contribution to sea level in a warmer-than-modern world. Climate models and ice sheet models can be used to enhance our understanding of ice sheet stability; however, uncertainties associated with different ice-sheet modelling frameworks mean that a rigorous comparison of numerical ice sheet model simulations for the Pliocene is essential. As an extension to the Pliocene Model Intercomparison Project (PlioMIP; Haywood et al., 2010, 2011a), the Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) will provide the first assessment as to the ice sheet model dependency of ice sheet predictions for the mPWP. Here we outline the PLISMIP experimental design and initialisation conditions that have been adopted to simulate the Greenland and Antarctic ice sheets under present-day and warm mid-Pliocene conditions. Not only will this project provide a new benchmark in the simulation of ice sheets in a past warm period, but the analysis of model sensitivity to various uncertainties could directly inform future predictions of ice sheet and sea level change.

Highlights

The General Circulation Models (GCM) and ice sheet models (ISM) used for simulating future climate change can be applied to retrodict past climatic and ice sheet changes
This will be a useful contribution to our understanding of the mid-Pliocene ice sheets, it should be reiterated that such an approach does not take into account all types of structural uncertainty within the ISM and this will need to be highlighted as a potential limitation of the results
This paper provides an overview of the experimental design for the Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP), which is being undertaken as part of Pliocene Model Intercomparison Project (PlioMIP), the latest addition to the Palaeoclimate Modelling Intercomparison Project (PMIP) experiments

Summary

Introduction

The General Circulation Models (GCM) and ice sheet models (ISM) used for simulating future climate change can be applied to retrodict past climatic and ice sheet changes. As the most recent period in Earth history with global temperatures and levels of atmospheric carbon dioxide (CO2) greater than today, the mid-Pliocene warm period (mPWP) provides an important target for palaeoclimate and ice sheet modelling. The mPWP “time slab” is a climatically distinct period, identifiable in marine core records, when the Earth experienced global mean temperatures higher than today. It represents one of the most accessible palaeoclimates to compare with model estimates of late 21st century climate (Haywood et al, 2011b). The most recent climate model predictions suggest that, during Pliocene interglacials, global annual mean temperatures were 2 to 3 ◦C higher than the Pre-industrial Era Much of the geological evidence for this time period is limited and disputed or controversial (see Hill et al, 2007)

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