The aim of this study is to place a paleo-constraint on climate sensitivity in the climateprediction.net ensemble. Sensitivity is here defined as the equilibrium temperature response to doubling of pre-industrial carbon dioxide concentrations. Some of the climateprediction.net models have shown a large sensitivity and by applying models to past climates, we are testing if the models and their corresponding sensitivity are realistic. The general circulation model results are compared to paleo-observations. We are aiming to provide a framework for the evaluation of the climate models to see if they are able to simulate climates that were different from today. This will improve our confidence in the models projections for future climates.
The period of focus is the mid-Holocene, i.e. ~6000 years before present (6kyBP). Why use the mid-Holocene climate to benchmark our models? The current climate is not in equilibrium. It is changing. The previous period in time with a stable climate was the mid-Holocene, when the climate was stable for a period of about 2000 years and the forcing on the climate is well known. The 6kyBP climate is reasonably well known through paleo- observations.
The model used is HadSM3, a state-of-the-art climate model from the Hadley Centre for Climate Prediction and Research Atmospheric General Circulation Model coupled to a slab ocean. Mid-Holocene boundary conditions are applied to the model, i.e. the orbital configuration is altered to represent that of 6000 years ago. This redistributes the latitudinal and seasonal distribution of incoming solar radiation at the top of the atmosphere in the model. The model you download consists of 4 different phases, each of 15 model years
Phase 1, (1810-1825) Calibration phase Phase 2, (1825-1840) Control phase Phase 3, (1825-1840) Mid-Holocene phase with altered boundary conditions Phase 4, (2050-2065) A phase with a doubling of the pre-industrial CO2-levels to find the sensitivity The difference in the model results between the mid-Holocene and control models are then compared to the paleo-observations available. A range of paleo-observations are used to test the models; pollen data, lake level data from lake sediment cores, macro fossil data and temperature data deduced from foraminifera, molluscs, diatoms, driftwood, whale fossils and whale bones.
HADSM3P Slab ModelHADSM3 Mid HoloceneHADCM3 Coupled ModelHADAM3 / SAPHADRM3HADCM3L Pacific North WestHADCM3L Southern AfricaHADAM3PHADSM3 Slab ModelFAMOUSHadAM3P-HadRM3P EuropeHADAM3P Southern AfricaHadAM3P-HadRM3P Pacific North WestHADCM3LHadAM3P-HadRM3P Australia New ZealandHadAM3P-HadRM3P AfricaHadAM3P (global only) with MOSES II landsurface schemeHadAM3P and HadRM3P model with MOSES II and TRIFFIDHadAM3P and HadRM3P model with MOSES II and TRIFFID East AsiaHadAM3P and HadRM3P model with MOSES II and TRIFFID Europe
UK Met Office HADAM3P European Region 6.09 UK Met Office HADAM3P Southern Africa 6.09 UK Met Office HADAM3P Pacific North West 7.22 UK Met Office HadCM3 6.07 UK Met Office HADAM3P Australia New Zealand 6.10
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UK Met Office HADCM3L 6.05 UK Met Office HADAM3P European Region 6.10 UK Met Office HADAM3P Southern Africa 6.10 UK Met Office HADAM3P Pacific North West 7.22 UK Met Office HadCM3 6.07 UK Met Office HADCM3L 6.05 UK Met Office HADAM3P MOSES II 7.02 UK Met Office Africa 6.11 UK Met Office HADAM3P Australia New Zealand 6.10 UK Met Office HADAM3P Africa 6.11
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UK Met Office HADAM3P European Region 6.09 UK Met Office HADAM3P Southern Africa 6.09 UK Met Office HADAM3P Pacific North West 7.22 UK Met Office HadCM3 6.07 UK Met Office HADAM3P Australia New Zealand 6.10
