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The PMIP4 contribution to CMIP6 - Part 3: the Last Millennium, Scientific Objective and Experimental Design for the PMIP4 <i>past1000</i> simulations

Type of publication Not peer-reviewed
Publikationsform Original article (non peer-reviewed)
Publication date 2016
Author Jungclaus Johann H., Bard Edouard, Baroni Mélanie, Braconnot Pascale, Cao Jian, Chini Louise P., Egorova Tania, Evans Michael, González-Rouco J. Fidel, Goosse Hugues, Hurtt Georges C., Joos Fortunat, Kaplan Jed O., Khodri Myriam, Klein Goldewijk Kees, Krivova Natalie, LeGrande Allegra N., Lorenz Stephan J., Luterbacher Jürg, Man Wenmin, Meinshausen Malte, Moberg Anders, Nehrbass-Ahles Christian, Otto-Bliesner Bette I., et al.,
Project Future and Past Solar Influence on the Terrestrial Climate II
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Original article (non peer-reviewed)

Journal Geoscientific Model Development Discussions
Page(s) 1 - 34
Title of proceedings Geoscientific Model Development Discussions
DOI 10.5194/gmd-2016-278

Open Access

Type of Open Access Publisher (Gold Open Access)


The pre-industrial millennium is among the periods selected by the Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) and the fourth phase of PMIP (PMIP4). The past1000 transient simulations serve to investigate the response to (mainly) natural forcing under background conditions not too different from today, and to discriminate between forced and internally generated variability on interannual to centennial time scales. This manuscript describes the motivation and the experimental set-ups for the PMIP4-CMIP6 past1000 simulations, and discusses the forcing agents: orbital, solar, volcanic, land-use/land-cover changes, and variations in greenhouse gas concentrations. The past1000 simulations covering the pre-industrial millennium from 850 Common Era (CE) to 1849 CE have to be complemented by historical simulations (1850 to 2014 CE) following the CMIP6 protocol. The external forcings for the past1000 experiments have been adapted to provide a seamless transition across these time periods. Protocols for the past1000 simulations have been divided into three tiers. A default forcing data set has been defined for the “tier-1” (the CMIP6 past1000) experiment. However, the PMIP community has maintained the flexibility to conduct coordinated sensitivity experiments to explore uncertainty in forcing reconstructions as well as parameter uncertainty in dedicated “tier-2” simulations. Additional experiments (“tier-3”) are defined to foster collaborative model experiments focusing on the early instrumental period and to extend the temporal range and the scope of the simulations. This manuscript outlines current and future research foci and common analyses for collaborative work between the PMIP and the observational communities (reconstructions, instrumental data).