Pierre Sepulchre

selected publications

1. 

   Orbital variations as a major driver of climate and biome distribution during the greenhouse to icehouse transition

   Delphine Tardif, Agathe Toumoulin, Frédéric Fluteau, and 9 more authors

   Science Advances 2021

   Abstract Bib PDF

   Recent studies suggest increasing sensitivity to orbital variations across the Eocene-Oligocene greenhouse to icehouse climate transition. However, climate simulations and paleoenvironmental studies mostly provide snapshots of the past climate, therefore overlooking the role of this short-term variability in driving major environmental changes and possibly biasing model-data comparisons. We address this problem by performing numerical simulations describing the end-members of eccentricity, obliquity, and precession. The orbitally induced biome variability obtained in our simulations allows to reconcile previous apparent mismatch between models and paleobotanical compilations. We show that precession-driven intermittent monsoon-like climate may have taken place during the Eocene, resulting in biomes shifting from shrubland to tropical forest in the intertropical convergence zone migration region. Our Oligocene simulations suggest that, along with decreased pCO2, orbital variations crucially modulated major faunal dispersal events around the EOT such as the Grande Coupure by creating and fragmenting the biome corridors along several key land bridges.

   @article{tardif:insu-03401267,
     title = {{Orbital variations as a major driver of climate and biome distribution during the greenhouse to icehouse transition}},
     author = {Tardif, Delphine and Toumoulin, Agathe and Fluteau, Fr{\'e}d{\'e}ric and Donnadieu, Yannick and Le Hir, Guillaume and Barbolini, Natasha and Licht, Alexis and Ladant, Jean-Baptiste and Sepulchre, Pierre and Viovy, Nicolas and Hoorn, Carina and Dupont-Nivet, Guillaume},
     url = {https://hal-insu.archives-ouvertes.fr/insu-03401267},
     journal = {{Science Advances }},
     publisher = {{American Association for the Advancement of Science (AAAS)}},
     volume = {7},
     number = {43},
     year = {2021},
     doi = {10.1126/sciadv.abh2819},
     hal_id = {insu-03401267},
     hal_version = {v1},
   }

2. 

   IPSL-CM5A2 – an Earth system model designed for multi-millennial climate simulations

   Pierre Sepulchre, Arnaud Caubel, Jean-Baptiste Ladant, and 25 more authors

   Geoscientific Model Development Jul 2020

   Abstract Bib HTML PDF

   Based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5)-generation previous Institut Pierre Simon Laplace (IPSL) Earth system model, we designed a new version, IPSL-CM5A2, aiming at running multi-millennial simulations typical of deep-time paleoclimate studies. Three priorities were followed during the setup of the model: (1) improving the overall model computing performance, (2) overcoming a persistent cold bias depicted in the previous model generation and (3) making the model able to handle the specific continental configurations of the geological past. These developments include the integration of hybrid parallelization Message Passing Interface – Open Multi-Processing (MPI-OpenMP) in the atmospheric model of the Laboratoire de Météorologie Dynamique (LMDZ), the use of a new library to perform parallel asynchronous input/output by using computing cores as “I/O servers” and the use of a parallel coupling library between the ocean and the atmospheric components. The model, which runs with an atmospheric resolution of 3.75∘×1.875∘ and 2 to 0.5∘ in the ocean, can now simulate ∼100 years per day, opening new possibilities towards the production of multi-millennial simulations with a full Earth system model. The tuning strategy employed to overcome a persistent cold bias is detailed. The confrontation of a historical simulation to climatological observations shows overall improved ocean meridional overturning circulation, marine productivity and latitudinal position of zonal wind patterns. We also present the numerous steps required to run IPSL-CM5A2 for deep-time paleoclimates through a preliminary case study for the Cretaceous. Namely, specific work on the ocean model grid was required to run the model for specific continental configurations in which continents are relocated according to past paleogeographic reconstructions. By briefly discussing the spin-up of such a simulation, we elaborate on the requirements and challenges awaiting paleoclimate modeling in the next years, namely finding the best trade-off between the level of description of the processes and the computing cost on supercomputers.

   @article{sepulchre:hal-02893945,
     title = {{IPSL-CM5A2 -- an Earth system model designed for multi-millennial climate simulations}},
     author = {Sepulchre, Pierre and Caubel, Arnaud and Ladant, Jean-Baptiste and Bopp, Laurent and Boucher, Olivier and Braconnot, Pascale and Brockmann, Patrick and Cozic, Anne and Donnadieu, Yannick and Dufresne, Jean-Louis and Estella-Perez, Victor and {\'E}th{\'e}, Christian and Fluteau, Fr{\'e}d{\'e}ric and Foujols, Marie-Alice and GASTINEAU, GUILLAUME and Ghattas, Josefine and Hauglustaine, Didier and Hourdin, Fr{\'e}d{\'e}ric and Kageyama, Masa and Khodri, Myriam and Marti, Olivier and Meurdesoif, Yann and Mignot, Juliette and Sarr, Anta-Clarisse and Servonnat, J{\'e}r{\^o}me and Swingedouw, Didier and Laval-Szopa, Sophie and Tardif, Delphine},
     journal = {{Geoscientific Model Development}},
     publisher = {{European Geosciences Union}},
     volume = {13},
     number = {7},
     pages = {3011-3053},
     year = {2020},
     month = jul,
     doi = {10.5194/gmd-13-3011-2020},
     hal_id = {hal-02893945},
     hal_version = {v1},
   }

3. 

   Tectonics, climate and the diversification of the tropical African terrestrial flora and fauna

   Thomas L P Couvreur, Gilles Dauby, Anne Blach-Overgaard, and 23 more authors

   Biological Reviews Jul 2021

   Abstract Bib PDF

   Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to an increased understanding of the diversification and speciation processes generating tropical African biodiversity. In parallel, extended geological and palaeoclimatic records together with detailed numerical simulations have refined our understanding of past geological and climatic changes in Africa. To date, these important advances have not been reviewed within a common framework. Here, we critically review and synthesize African climate, tectonics and terrestrial biodiversity evolution throughout the Cenozoic to the mid-Pleistocene, drawing on recent advances in Earth and life sciences. We first review six major geo-climatic periods defining tropical African biodiversity diversification by synthesizing 89 dated molecular phylogeny studies. Two major geo-climatic factors impacting the diversification of the sub-Saharan biota are highlighted. First, Africa underwent numerous climatic fluctuations at ancient and more recent timescales, with tectonic, greenhouse gas, and orbital forcing stimulating diversification. Second, increased aridification since the Late Eocene led to important extinction events, but also provided unique diversification opportunities shaping the current tropical African biodiversity landscape. We then review diversification studies of tropical terrestrial animal and plant clades and discuss three major models of speciation: (i) geographic speciation via vicariance (allopatry); (ii) ecological speciation impacted by climate and geological changes, and (iii) genomic speciation via genome duplication. Geographic speciation has been the most widely documented to date and is a common speciation model across tropical Africa. We conclude with four important challenges faced by tropical African biodiversity research: (i) to increase knowledge by gathering basic and fundamental biodiversity information; (ii) to improve modelling of African geophysical evolution throughout the Cenozoic via better constraints and downscaling approaches; (iii) to increase the precision of phylogenetic reconstruction and molecular dating of tropical African clades by using next generation sequencing approaches together with better fossil calibrations; (iv) finally, as done here, to integrate data better from Earth and life sciences by focusing on the interdisciplinary study of the evolution of tropical African biodiversity in a wider geodiversity context.

   @article{couvreur:insu-02940669,
     title = {{Tectonics, climate and the diversification of the tropical African terrestrial flora and fauna}},
     author = {Couvreur, Thomas L P and Dauby, Gilles and Blach-Overgaard, Anne and Deblauwe, Vincent and Dessein, Steven and Droissart, Vincent and Hardy, Oliver J and Harris, David J and Janssens, Steven B and Ley, Alexandra C and MacKinder, Barbara A and Sonk{\'e}, Bonaventure and Sosef, Marc S M and St{\'e}vart, Tariq and Svenning, Jens-Christian and Wieringa, Jan J and Faye, Adama and Missoup, Alain D and Tolley, Krystal A and Nicolas, Violaine and Ntie, St{\'e}phan and Fluteau, Fr{\'e}di{\'e}ric and Robin, C{\'e}cile and Guillocheau, Francois and Barboni, Doris and Sepulchre, Pierre},
     url = {https://hal-insu.archives-ouvertes.fr/insu-02940669},
     journal = {{Biological Reviews}},
     hal_local_reference = {SYSTE},
     publisher = {{Wiley}},
     volume = {96},
     number = {1},
     pages = {16-51},
     year = {2021},
     doi = {10.1111/brv.12644},
     keywords = {Cenozoic ; African geology ; fossils ; speciation models ; palaeoclimate models ; dated molecular phylogenies ; tropical Africa},
     hal_id = {insu-02940669},
     hal_version = {v1},
   }