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Climate of the Past An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/cp-2019-160
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-2019-160
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 13 Jan 2020

Submitted as: research article | 13 Jan 2020

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This preprint is currently under review for the journal CP.

The UK contribution to CMIP6/PMIP4: mid-Holocene and Last Interglacial experiments with HadGEM3, and comparison to the pre-industrial era and proxy data

Charles J. R. Williams1,5, Maria-Vittoria Guarino2, Emilie Capron3, Irene Malmierca-Vallet1,2, Joy S. Singarayer4,1, Louise C. Sime2, Daniel J. Lunt1, and Paul J. Valdes1 Charles J. R. Williams et al.
  • 1School of Geographical Sciences, University of Bristol, UK
  • 2British Antarctic Survey, Cambridge, UK
  • 3Physics of Ice, Climate and Earth, Niels Bohr Institute, University of Copenhagen, Denmark
  • 4Department of Meteorology & School of Archaeology, Geography and Environmental Science, University of Reading, UK
  • 5NCAS-Climate / Departmentof Meteorology, University of Reading, UK

Abstract. Palaeoclimate model simulations are an important tool to improve our understanding of the mechanisms of climate change. These simulations also provide tests of the ability of models to simulate climates very different to today. Here we present the results from two simulations using the latest version of the UK’s physical climate model, HadGEM3-GC3.1; the mid-Holocene (~ 6 ka) and Last Interglacial (~ 127 ka) simulations, both conducted under the auspices of CMIP6/PMIP4. These periods are of particular interest to PMIP4 because they represent the two most recent warm periods in Earth history, where atmospheric concentration of greenhouse gases and continental configuration is similar to the pre-industrial period but where there were significant changes to the Earth’s orbital configuration, resulting in a very different seasonal cycle of radiative forcing.

Results for these simulations are assessed against proxy data, previous versions of the UK model, and models from the previous CMIP5 exercise. When the current version is compared to the previous generation of the UK model, the most recent version suggests limited improvement. In common with these previous model versions, the simulations reproduce global land and ocean temperatures (both surface and at 1.5 m) and a West African monsoon that is consistent with the latitudinal and seasonal distribution of insolation. The Last Interglacial simulation appears to accurately capture Northern Hemisphere temperature changes, but without the addition of Last Interglacial meltwater forcing cannot capture the magnitude of Southern Hemisphere changes. Model-data comparisons indicate that some geographical regions, and some seasons, produce better matches to the palaeodata (relative to pre-industrial) than others. Model-model comparisons, relative to previous generations same model and other models, indicate similarity between generations in terms of both the intensity and northward enhancement of the mid-Holocene West African monsoon, both of which are underestimated. On the Saharan greening which occurred the mid-Holocene African Humid Period, simulation results are likewise consistent with other models. The most recent version of the UK model appears to still be unable to reproduce the amount of rainfall necessary to support grassland across the Sahara.

Charles J. R. Williams et al.

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Charles J. R. Williams et al.

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Latest update: 04 Apr 2020
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Short summary
Computer simulations of the geological past are an important tool to improve our understanding of climate change. We present results from two simulations using the latest version of the UK’s climate model, the mid-Holocene (6000 years ago) and Last Interglacial (127 000 years ago). The simulations reproduce temperatures consistent with the pattern of incoming radiation. Model-data comparisons indicate that some regions, and some seasons, produce better matches to the data than others.
Computer simulations of the geological past are an important tool to improve our understanding...
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