Articles | Volume 13, issue 11
Clim. Past, 13, 1661–1684, 2017

Special issue: Southern perspectives on climate and the environment from...

Clim. Past, 13, 1661–1684, 2017

Research article 24 Nov 2017

Research article | 24 Nov 2017

Evaluation of PMIP2 and PMIP3 simulations of mid-Holocene climate in the Indo-Pacific, Australasian and Southern Ocean regions

Duncan Ackerley1, Jessica Reeves2, Cameron Barr3,4, Helen Bostock5, Kathryn Fitzsimmons6, Michael-Shawn Fletcher7, Chris Gouramanis8, Helen McGregor9, Scott Mooney10, Steven J. Phipps11, John Tibby3,4, and Jonathan Tyler3,4 Duncan Ackerley et al.
  • 1ARC Centre of Excellence for Climate System Science, School of Earth, Atmosphere and Environment, Monash University, Victoria 3800, Australia
  • 2Federation University, Faculty of Science and Technology, Mt Helen, Ballarat, Victoria 3353, Australia
  • 3Department of Geography, Environment and Population, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
  • 4Sprigg Geobiology Centre, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia
  • 5National Institute of Water and Atmospheric Research, 301 Evans Bay Parade, Greta Point, Wellington, New Zealand
  • 6Research Group for Terrestrial Paleoclimates, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
  • 7School of Geography, University of Melbourne, Parkville, Victoria 3010, Australia
  • 8Department of Geography, National University of Singapore, 10 Kent Ridge Crescent, Singapore 117570, Singapore
  • 9School of Earth and Environmental Sciences, University of Wollongong, Northfields Ave, Wollongong, NSW 2522, Australia
  • 10School of Biological, Earth and Environmental Science, UNSW, Sydney, NSW 2052, Australia
  • 11Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia

Abstract. This study uses the simplified patterns of temperature and effective precipitation approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records – OZ-INTIMATE) to compare atmosphere–ocean general circulation model (AOGCM) simulations and proxy reconstructions. The approach is used in order to identify important properties (e.g. circulation and precipitation) of past climatic states from the models and proxies, which is a primary objective of the Southern Hemisphere Assessment of PalaeoEnvironment (SHAPE) initiative. The AOGCM data are taken from the Paleoclimate Modelling Intercomparison Project (PMIP) mid-Holocene (ca. 6000 years before present, 6 ka) and pre-industrial control (ca. 1750 CE, 0 ka) experiments. The synthesis presented here shows that the models and proxies agree on the differences in climate state for 6 ka relative to 0 ka, when they are insolation driven. The largest uncertainty between the models and the proxies occurs over the Indo-Pacific Warm Pool (IPWP). The analysis shows that the lower temperatures in the Pacific at around 6 ka in the models may be the result of an enhancement of an existing systematic error. It is therefore difficult to decipher which one of the proxies and/or the models is correct. This study also shows that a reduction in the Equator-to-pole temperature difference in the Southern Hemisphere causes the mid-latitude westerly wind strength to reduce in the models; however, the simulated rainfall actually increases over the southern temperate zone of Australia as a result of higher convective precipitation. Such a mechanism (increased convection) may be useful for resolving disparities between different regional proxy records and model simulations. Finally, after assessing the available datasets (model and proxy), opportunities for better model–proxy integrated research are discussed.

Short summary
A selection of climate models have been used to simulate both pre-industrial (1750 CE) and mid-Holocene (6000 years ago) conditions. This study presents an assessment of the temperature, rainfall and flow over Australasia from those climate models. The model data are compared with available proxy data reconstructions (e.g. tree rings) for 6000 years ago to identify whether the models are reliable. Places where there is both agreement and conflict are highlighted and investigated further.