UK Contribution to Plio-MIP (Pliocene Modelling Intercomaprison Project)

Lead Research Organisation: University of Leeds
Department Name: School of Earth and Environment


Advanced numerical models of climate, often referred to as General Circulation Models, are being extensively used to predict the impacts of human induced climate change on global and regional scales. Although advanced such models remain imperfect tools with which to simulate climate change, and thus the robustness of climate models must be tested so that confidence in their predictions can be increased. There is no way climate model predictions for the future can directly test, but scientists can evaluate the capability of state of the art climate models to reproduce climate states that existed in the past and that were radically different from those of today. Since the mid 1990's an international programme called PMIP (Palaeoclimate Modelling Intercomparison Project) has championed the systematic study of several climate models and assessed their ability to simulate large changes of climate that occurred in the past. However, PMIP has not studied a period in Earth history that was globally warmer than present-day, and which had higher than pre-industrial levels of carbon dioxide (a greenhouse gas) in the atmosphere. In other words PMIP has not examined the ability of, and determined the differences between, climate models when simulating a period in Earth's history that provides a close analogue to climate as it is predicted to be in the future, as a result of human modification. The project will help fill this gap and enable a leading UK contribution to a new project set up to systematically study climate model outputs for a warm period in Earth history (the mid-Pliocene warm period ca 3 to 3.3 million years before present) which has a number of parallels to climate predictions for the end of this century. The recent Intergovernmental Panel on Climate Change (IPCC) 4th assessment report states that 'the mid-Pliocene is the most recent interval of geological time when mean global temperatures were ~2 to 3 degrees Celsius above pre-industrial temperatures for a sustained period. Therefore, the mid-Pliocene represents an accessible example of a world that is similar in many respects to what models estimate could be the Earth of the late 21st century'. In June 2008 representatives from 10 climate modelling groups worldwide met in New York to discuss and agree the details of new climate model simulations that will be carried out for the mid-Pliocene. This proposal outlines the programme of work and resources necessary to allow the UK to take part in this exciting new international initiative. It is expected that outcomes from this new project will be included in the next Intergovernmental Panel on Climate Change report, thereby helping to inform scientists and politicians worldwide about the ability and differences between climate models in simulating the last great period of sustained global warmth in our planets long history.
Description Preamble: This project provided the UK contribution to PlioMIP. The report outlines the programme of work completed which has allowed the UK to take a full part in Phase 1 of this new international project. The PlioMIP programme is enabling the systematic study of climate models (GCMs) for a warm period in Earth history that has parallels to climate predictions for the end of this century. The UK is able to take a leading role in this initiative, PI Haywood is the lead coordinator for the programme and Co-I Lunt is a member of the PlioMIP advisory board.

Programme of Work: This project involved completion of two new mid-Pliocene General Circulation Model simulations, one using the atmosphere-only model HadAM3 and the second using a fully coupled ocean-atmosphere model HadCM3, with accompanying controls (present-day experiments). These simulations made use of the latest generation of boundary conditions available for the mid-Pliocene produced by the United States Geological Survey PRISM Project (Pliocene Research Interpretations and Synoptic Mapping Project - generation 3). This includes updated estimates for sea surface temperature, sea-ice cover, global land cover, orography and ice sheet extent compared to the previous generation of the PRISM data set (PRISM2). Please refer to the PRISM web site for details of the PRISM3 data set that were utilized within HadCM3 and HadAM3 (

The simulations have been completed as planned and the data submitted to the Palaeoclimate Modelling Intercomparison Project Database. In addition to this we have carried out an additional two control experiments using HadAM3 and HadCM3 in order to determine the impact on the climate anomaly (Pliocene minus present-day) of using either anthropogenically modified vegetation (i.e. including land use in the control experiment) or using a new estimate of potential natural vegetation which does not include land use.


• 2 Pliocene simulations for PlioMIP using HadAM3 and HadCM3

• 4 control (present-day) simulations to accompany the above (with and without land-use)

• Lead author paper in Global and Planetary Change comparing HadAM3 simulations of the Pliocene with the Goddard Institute for Space Studies Model

• 2 lead author papers in Geoscientific Model Development outlining the boundary conditions and experimental design for PlioMIP Experiment 1 and Experiment 2

• Co-author paper in GMD describing boundary condition implementation within HadAM3 and CM3, basic details of predicted climate and differences in climate using potential natural vegetation versus vegetation incorporating land use in the control experiments.

• Conference presentations at AGU and EGU 2009 and EGU 2010.
Exploitation Route Nil This work is being used in the broad context of the PlioMIP programme.

It is being used by 14 international groups who are currently engaged in analyzing Pliocene climates.

It has contributed towards a multi-model study of Pliocene monsoons, ocean circulation, data/model comparison studies (x 2).

This work will continue and the data used in a number of additional publications in the future.
Sectors Environment