Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 12, 1619-1634, 2016
http://www.clim-past.net/12/1619/2016/
doi:10.5194/cp-12-1619-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
08 Aug 2016
Sensitivity of Pliocene climate simulations in MRI-CGCM2.3 to respective boundary conditions
Youichi Kamae1,2, Kohei Yoshida3, and Hiroaki Ueda1 1Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
2Scripps Institution of Oceanography, University of California San Diego, La Jolla, 92093-0206, USA
3Meteorological Research Institute, Tsukuba, 305-0052, Japan
Abstract. Accumulations of global proxy data are essential steps for improving reliability of climate model simulations for the Pliocene warming climate. In the Pliocene Model Intercomparison Project phase 2 (PlioMIP2), a part project of the Paleoclimate Modelling Intercomparison Project phase 4, boundary forcing data have been updated from the PlioMIP phase 1 due to recent advances in understanding of oceanic, terrestrial and cryospheric aspects of the Pliocene palaeoenvironment. In this study, sensitivities of Pliocene climate simulations to the newly archived boundary conditions are evaluated by a set of simulations using an atmosphere–ocean coupled general circulation model, MRI-CGCM2.3. The simulated Pliocene climate is warmer than pre-industrial conditions for 2.4 °C in global mean, corresponding to 0.6 °C warmer than the PlioMIP1 simulation by the identical climate model. Revised orography, lakes, and shrunk ice sheets compared with the PlioMIP1 lead to local and remote influences including snow and sea ice albedo feedback, and poleward heat transport due to the atmosphere and ocean that result in additional warming over middle and high latitudes. The amplified higher-latitude warming is supported qualitatively by the proxy evidences, but is still underestimated quantitatively. Physical processes responsible for the global and regional climate changes should be further addressed in future studies under systematic intermodel and data–model comparison frameworks.

Citation: Kamae, Y., Yoshida, K., and Ueda, H.: Sensitivity of Pliocene climate simulations in MRI-CGCM2.3 to respective boundary conditions, Clim. Past, 12, 1619-1634, doi:10.5194/cp-12-1619-2016, 2016.
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Short summary
Climate model simulations conducted in previous studies tended to underestimate the late-Pliocene higher-latitude warming suggested by proxy evidences. We explore how prescribed trace gases, ice sheets, vegetation, lakes and orography affect the Pliocene climate simulation based on a protocol of the PlioMIP Phase 2. The revised boundary forcing data lead to amplified higher-latitude warming that is qualitatively consistent with the paleoenvironment reconstructions.
Climate model simulations conducted in previous studies tended to underestimate the...
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