Oxygen stable isotopes during the Last Glacial Maximum climate: perspectives from data–model ( i LOVECLIM) comparison

• Published in: Climate of the Past
• Main Authors: Caley, Thibaut, Roche, Didier M., Waelbroeck, C., Michel, Elisabeth
• Other Authors: Vrije Universiteit Amsterdam Amsterdam (VU), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Modélisation du climat (CLIM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Paléocéanographie (PALEOCEAN)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Southern Ocean; Greenland; Indian; ice core; Ice Sheet; North Atlantic
• Online Access: https://hal.science/hal-02915948; https://hal.science/hal-02915948/document; https://hal.science/hal-02915948/file/cp-10-1939-2014.pdf; https://doi.org/10.5194/cp-10-1939-2014

International audience We use the fully coupled atmosphere-ocean three-dimensional model of intermediate complexity iLOVECLIM to simulate the climate and oxygen stable isotopic signal during the Last Glacial Maximum (LGM, 21 000 years). By using a model that is able to explicitly simulate the sensor (δ 18 O), results can be directly compared with data from climatic archives in the different realms. Our results indicate that iLOVECLIM reproduces well the main feature of the LGM climate in the atmospheric and oceanic components. The annual mean δ 18 O in precipitation shows more depleted values in the northern and southern high latitudes during the LGM. The model reproduces very well the spatial gradient observed in ice core records over the Greenland ice sheet. We observe a general pattern toward more enriched values for continental calcite δ 18 O in the model at the LGM, in agreement with speleothem data. This can be explained by both a general atmospheric cooling in the tropical and subtropical regions and a reduction in precipitation as confirmed by reconstruction derived from pollens and plant macrofossils. Data-model comparison for sea surface temperature indicates that iLOVECLIM is capable to satisfyingly simulate the change in oceanic surface conditions between the LGM and present. Our data-model comparison for calcite δ 18 O allows investigating the large discrepancies with respect to glacial temperatures recorded by different microfos-sil proxies in the North Atlantic region. The results argue for a strong mean annual cooling in the area south of Ice-land and Greenland between the LGM and present (> 6 °C), supporting the foraminifera transfer function reconstruction but in disagreement with alkenones and dinocyst reconstructions. The data-model comparison also reveals that large positive calcite δ 18 O anomaly in the Southern Ocean may be explained by an important cooling, although the driver of this pattern is unclear. We deduce a large positive δ 18 Osw anomaly for the north Indian Ocean that ...