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The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Otto-Bliesner Bette L., Braconnot Pascale, Harrison Sandy P., Lunt Daniel J., Abe-Ouchi Ayako, Albani Samuel, Bartlein Patrick J., Capron Emilie, Carlson Anders E., Dutton Andrea, Fischer Hubertus, Goelzer Heiko, Govin Aline, Haywood Alan, Joos Fortunat, LeGrande Allegra N., Lipscomb William H., Lohmann Gerrit, Mahowald Natalie, Nehrbass-Ahles Christoph, Pausata Francesco S. R., Peterschmitt Jean-Yves, Phipps Steven J., Renssen Hans, et al. ,
Project Climate and Environmental Physics: Modeling Global Biogeochemical Cycles in the Earth System (bgcCEP)
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Original article (peer-reviewed)

Journal Geoscientific Model Development
Volume (Issue) 10(11)
Page(s) 3979 - 4003
Title of proceedings Geoscientific Model Development
DOI 10.5194/gmd-10-3979-2017

Open Access

URL http://doi.org/10.5194/gmd-10-3979-2017
Type of Open Access Publisher (Gold Open Access)

Abstract

Abstract. Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last Interglacial (lig127k, 127 000 years before present) are described here. These equilibrium simulations are designed to examine the impact of changes in orbital forcing at times when atmospheric greenhouse gas levels were similar to those of the preindustrial period and the continental configurations were almost identical to modern ones. These simulations test our understanding of the interplay between radiative forcing and atmospheric circulation, and the connections among large-scale and regional climate changes giving rise to phenomena such as land–sea contrast and high-latitude amplification in temperature changes, and responses of the monsoons, as compared to today. They also provide an opportunity, through carefully designed additional sensitivity experiments, to quantify the strength of atmosphere, ocean, cryosphere, and land-surface feedbacks. Sensitivity experiments are proposed to investigate the role of freshwater forcing in triggering abrupt climate changes within interglacial epochs. These feedback experiments naturally lead to a focus on climate evolution during interglacial periods, which will be examined through transient experiments. Analyses of the sensitivity simulations will also focus on interactions between extratropical and tropical circulation, and the relationship between changes in mean climate state and climate variability on annual to multi-decadal timescales. The comparative abundance of paleoenvironmental data and of quantitative climate reconstructions for the Holocene and Last Interglacial make these two epochs ideal candidates for systematic evaluation of model performance, and such comparisons will shed new light on the importance of external feedbacks (e.g., vegetation, dust) and the ability of state-of-the-art models to simulate climate changes realistically.
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