Suchergebnisse

The penultimate deglaciation (PDG, ∼138–128 thousand years before present, hereafter ka) is the transition from the penultimate glacial maximum (PGM) to the Last Interglacial (LIG, ∼129–116 ka). The LIG stands out as one of the warmest interglacials of the last 800 000 years (hereafter kyr), with high-latitude temperature warmer than today and global sea level likely higher by at least 6 m. Considering the transient nature of the Earth system, the LIG climate and ice-sheet evolution were certainly influenced by the changes occurring during the penultimate deglaciation. It is thus important to investigate, with coupled atmosphere–ocean general circulation models (AOGCMs), the climate and environmental response to the large changes in boundary conditions (i.e. orbital configuration, atmospheric greenhouse gas concentrations, ice-sheet geometry and associated meltwater fluxes) occurring during the penultimate deglaciation. A deglaciation working group has recently been set up as part of the Paleoclimate Modelling Intercomparison Project (PMIP) phase 4, with a protocol to perform transient simulations of the last deglaciation (19–11 ka; although the protocol covers 26–0 ka). Similar to the last deglaciation, the disintegration of continental ice sheets during the penultimate deglaciation led to significant changes in the oceanic circulation during Heinrich Stadial 11 (∼136–129 ka). However, the two deglaciations bear significant differences in magnitude and temporal evolution of climate and environmental changes. Here, as part of the Past Global Changes (PAGES)-PMIP working group on Quaternary interglacials (QUIGS), we propose a protocol to perform transient simulations of the penultimate deglaciation under the auspices of PMIP4. This design includes time-varying changes in orbital forcing, greenhouse gas concentrations, continental ice sheets as well as freshwater input from the disintegration of continental ice sheets. This experiment is designed for AOGCMs to assess the coupled response of the climate system to all forcings. Additional sensitivity experiments are proposed to evaluate the response to each forcing. Finally, a selection of paleo-records representing different parts of the climate system is presented, providing an appropriate benchmark for upcoming model–data comparisons across the penultimate deglaciation. ; Laurie Menviel acknowledges funding from the Australian Research Council (grant nos. DE150100107 and DP180100048). Emilie Capron received funding from the European Union's Seventh Framework Programme for research and innovation under the Marie Skłodowska-Curie grant agreement no. 600207. Eric Wolff is supported by a Royal Society professorship. His part in this project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 742224). Polychronis C. Tzedakis and Ruza F. Ivanovic acknowledge funding from NERC (grant nos. NE/G00756X/1 to Polychronis C. Tzedakis and NE/K008536/1 to Ruza F. Ivanovic). Masa Kageyama is funded by the CNRS. Andrea Dutton acknowledges U.S. National Science Foundation (NSF) (grant nos. 1559040 and 1702740). Bette Otto-Bliesner's contributions are based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the U.S. NSF under Cooperative Agreement no. 1852977, with additional funding provided by an NSF P2C2 grant (grant no. AGS-1401803). Feng He was supported by the NSF (grant no. AGS-1502990) and by the NOAA Climate and Global Change Postdoctoral Fellowship program, administered by the University Corporation for Atmospheric Research. Xu Zhang is supported by Helmholtz Postdoc Program (PD-301) and the Chinese "The Thousand Talents Plan" Program. Ayako Abe-Ouchi, Kenji Kawamura and Ikumi Oyabu acknowledge support by JSPS KAKENHI (grant nos. 17H06104 to Ayako Abe-Ouchi, 15KK0027 and 26241011 to Kenji Kawamura, 17K12816 and 17J00769 to Ikumi Oyabu), and MEXT KAKENHI (grant nos. 17H06323 to Ayako Abe-Ouchi and 17H06320 to Kenji Kawamura).