29 results on '"Louise C. Sime"'
Search Results
2. Sea ice feedbacks influence the isotopic signature of Greenland ice sheet elevation changes: last interglacial HadCM3 simulations
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Irene Malmierca-Vallet, Paul J. Valdes, Julia Tindall, and Louise C. Sime
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010504 meteorology & atmospheric sciences ,lcsh:Environmental protection ,Stratigraphy ,Greenland ice sheet ,Climate change ,010502 geochemistry & geophysics ,01 natural sciences ,lcsh:Environmental pollution ,Ice core ,Sea ice ,lcsh:TD169-171.8 ,skin and connective tissue diseases ,lcsh:Environmental sciences ,Sea level ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Lead (sea ice) ,Paleontology ,13. Climate action ,lcsh:TD172-193.5 ,Interglacial ,Climate model ,sense organs ,Physical geography ,Geology - Abstract
Changes in the Greenland ice sheet (GIS) affect global sea level. Greenland stable water isotope (δ18O) records from ice cores offer information on past changes in the surface of the GIS. Here, we use the isotope-enabled Hadley Centre Coupled Model version 3 (HadCM3) climate model to simulate a set of last interglacial (LIG) idealised GIS surface elevation change scenarios focusing on GIS ice core sites. We investigate how δ18O depends on the magnitude and sign of GIS elevation change and evaluate how the response is altered by sea ice changes. We find that modifying GIS elevation induces changes in Northern Hemisphere atmospheric circulation, sea ice and precipitation patterns. These climate feedbacks lead to ice-core-averaged isotopic lapse rates of 0.49 ‰ (100 m)−1 for the lowered GIS states and 0.29 ‰ (100 m)−1 for the enlarged GIS states. This is lower than the spatially derived Greenland lapse rates of 0.62–0.72 ‰ (100 m)−1. These results thus suggest non-linearities in the isotope–elevation relationship and have consequences for the interpretation of past elevation and climate changes across Greenland. In particular, our results suggest that winter sea ice changes may significantly influence isotope–elevation gradients: winter sea ice effect can decrease (increase) modelled core-averaged isotopic lapse rate values by about −19 % (and +28 %) for the lowered (enlarged) GIS states, respectively. The largest influence of sea ice on δ18O changes is found in coastal regions like the Camp Century site.
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- 2020
3. Sea-ice-free Arctic during the Last Interglacial supports fast future loss
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Alistair Sellar, Erica Bree Rosenblum, David Schroeder, Julienne Stroeve, Cecilia M. Bitz, Mark A. Ringer, Irene Malmierca-Vallet, Eric J. Steig, Louise C. Sime, Maria-Vittoria Guarino, Eric W. Wolff, Daniel Feltham, Jeff Ridley, Guarino, MV [0000-0002-7531-4560], Sime, LC [0000-0002-9093-7926], Schröeder, D [0000-0003-2351-4306], Malmierca-Vallet, I [0000-0002-2871-9741], Bitz, C [0000-0002-9477-7499], Steig, EJ [0000-0002-8191-5549], Wolff, E [0000-0002-5914-8531], Sellar, A [0000-0002-2955-7254], and Apollo - University of Cambridge Repository
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13 Climate Action ,0303 health sciences ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,sub-01 ,37 Earth Sciences ,3705 Geology ,3709 Physical Geography and Environmental Geoscience ,Environmental Science (miscellaneous) ,Before Present ,01 natural sciences ,Arctic ice pack ,Latitude ,03 medical and health sciences ,Arctic ,13. Climate action ,Climatology ,Interglacial ,Sea ice ,Period (geology) ,Climate model ,Social Sciences (miscellaneous) ,030304 developmental biology ,0105 earth and related environmental sciences - Abstract
The Last Interglacial (LIG), a warmer period 130,000–116,000 years before present, is a potential analogue for future climate change. Stronger LIG summertime insolation at high northern latitudes drove Arctic land summer temperatures 4–5 °C higher than in the pre-industrial era. Climate model simulations have previously failed to capture these elevated temperatures, possibly because they were unable to correctly capture LIG sea-ice changes. Here, we show that the latest version of the fully coupled UK Hadley Center climate model (HadGEM3) simulates a more accurate Arctic LIG climate, including elevated temperatures. Improved model physics, including a sophisticated sea-ice melt-pond scheme, result in a complete simulated loss of Arctic sea ice in summer during the LIG, which has yet to be simulated in past generations of models. This ice-free Arctic yields a compelling solution to the long-standing puzzle of what drove LIG Arctic warmth and supports a fast retreat of future Arctic summer sea ice. Arctic climate in the Last Interglacial (LIG)—a warm period 130,000–116,000 years ago—is poorly simulated by modern climate models. A model with improved sea-ice melt-pond physics reproduces LIG Arctic temperatures, suggests an ice-free Arctic during this period and predicts the same by 2035.
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- 2020
4. Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e
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Matthew Chadwick, Claire S. Allen, Louise C. Sime, Claus-Dieter Hillenbrand, and Xavier Crosta
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Marine isotope stage ,010504 meteorology & atmospheric sciences ,Stratigraphy ,Antarctic sea ice ,Environmental protection ,01 natural sciences ,Environmental pollution ,03 medical and health sciences ,TD169-171.8 ,Sea ice ,GE1-350 ,14. Life underwater ,Glacial period ,Meltwater ,Southern Hemisphere ,030304 developmental biology ,0105 earth and related environmental sciences ,Polar front ,0303 health sciences ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Global warming ,Paleontology ,Environmental sciences ,Oceanography ,TD172-193.5 ,13. Climate action ,Environmental science - Abstract
Environmental conditions during Marine Isotope Stage (MIS) 5e (130–116 ka) represent an important “process analogue” for understanding the climatic responses to present and future anthropogenic warming. The response of Antarctic sea ice to global warming is particularly uncertain due to the short length of the observational record. Reconstructing Antarctic winter sea-ice extent during MIS 5e therefore provides insights into the temporal and spatial patterns of sea-ice change under a warmer-than-present climate. This study presents new MIS 5e records from nine marine sediment cores located south of the Antarctic Polar Front between 55 and 70∘ S. Winter sea-ice extent and sea-surface temperatures are reconstructed using marine diatom assemblages and a modern analogue technique transfer function, and changes in these environmental variables between the three Southern Ocean sectors are investigated. The Atlantic and East Indian sector records show much more variable MIS 5e winter sea-ice extent and sea-surface temperatures than the Pacific sector records. High variability in the Atlantic sector winter sea-ice extent is attributed to high glacial meltwater flux in the Weddell Sea, indicated by increased abundances of the diatom species Eucampia antarctica and Fragilariopsis cylindrus. The high variability in the East Indian sector winter sea-ice extent is conversely believed to result from large latitudinal migrations of the flow bands of the Antarctic Circumpolar Current, inferred from latitudinal shifts in the sea-surface temperature isotherms. Overall, these findings suggest that Pacific sector winter sea ice displays a low sensitivity to warmer climates. The different variability and sensitivity of Antarctic winter sea-ice extent in the three Southern Ocean sectors during MIS 5e may have significant implications for the Southern Hemisphere climatic system under future warming.
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- 2021
5. Large-scale features of Last Interglacial climate: Results from evaluating the lig127k simulations for the Coupled Model Intercomparison Project (CMIP6)-Paleoclimate Modeling Intercomparison Project (PMIP4)
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Yarrow Axford, Ayako Abe-Ouchi, Maria-Vittoria Guarino, Qiong Zhang, Elizabeth B. Isaacs, Bette L. Otto-Bliesner, Robert A. Tomas, Jeremy S. Hoffman, Zhongshi Zhang, Anne de Vernal, Nicholas K. H. Yeung, Masa Kageyama, Weipeng Zheng, Katrin J. Meissner, Christian Stepanek, Jian Cao, Chris Brierley, Gerrit Lohmann, Anni Zhao, Laurie Menviel, David Salas y Mélia, Polina Morozova, Louise C. Sime, Eric W. Wolff, Ryouta O'ishi, Silvana Ramos Buarque, Emilie Capron, Allegra N. LeGrande, Charles Williams, Marie Sicard, Polychronis C Tzedakis, Pascale Braconnot, Evgeny Volodin, Chuncheng Guo, Esther C. Brady, Xaoxu Shi, Paolo Scussolini, Aline Govin, Kerim H. Nisancioglu, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Climat et Magnétisme (CLIMAG), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Modélisation du climat (CLIM), Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics (MERMAID), National Science Foundation, NSF National Center for Atmospheric Research, NCAR: 1852977 Natural Environment Research Council, NERC: NE/S009736/1 Nederlandse Organisatie voor Wetenschappelijk Onderzoek, NWO: ALWOP.164 Sorbonne Université California Earthquake Authority, CEA Carlsbergfondet École Polytechnique Fédérale de Lausanne, EPFL Royal Society Centre National d’Etudes Spatiales, CNES 742224 European Research Council, ERC NE/P01903X/1, ANR-18-BELM-0001-06 312979 Centre National de la Recherche Scientifique, CNRS RSF Social Finance: 20-17-00190 Natural Environment Research Council, NERC: NE/P013279/1 Vetenskapsrådet, VR Bundesministerium für Bildung und Forschung, BMBF Vetenskapsrådet, VR: 2016-07213, 2013-06476, 2017-04232 Achievement Rewards for College Scientists Foundation, ARCS: JPMXD1300000000 JPMXD1420318865 Australian Research Council, ARC: FT180100606 2016YFC1401401 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, AWI Japan Society for the Promotion of Science, KAKEN: 17H06104 Ministry of Education, Culture, Sports, Science and Technology, Monbusho: 17H06323 Chinese Academy of Sciences, CAS: XDB42000000, XDA19060102 Japan Agency for Marine-Earth Science and Technology, JAMSTEC: 0148-2019-0009 National Natural Science Foundation of China, NSFC: 91958201and 41376002 National Science Foundation, NSF Chinese Academy of Sciences, CAS Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF Akademie der Naturwissenschaften, SCNAT National Science Foundation, NSF: 1852977 National Center for Atmospheric Research, NCAR, Acknowledgements. Bette L. Otto-Bliesner, Esther C. Brady and Robert Tomas acknowledge the CESM project, which is supported primarily by the National Science Foundation (NSF). This material is based upon work supported by the National Center for Atmospheric Research (NCAR), which is a major facility sponsored by the NSF under Cooperative Agreement No. 1852977. Computing and data storage resources, including the Cheyenne supercomputer (https://doi.org/10.5065/D6RX99HX), were provided by the Computational and Information Systems Laboratory (CISL) at NCAR. Chris M. Brierley acknowledges the financial support of the Natural Environment Research Council through grant NE/S009736/1. Anni Zhao and Chris M. Brierley would like to thank Rachel Eyles for her sterling work curating the local replica of the PMIP archive at UCL., Charles J. R. Williams acknowledges the financial support of the UK Natural Environment Research Council-funded SWEET project (Super-Warm Early Eocene Temperatures), research grant NE/P01903X/1, and the financial support of the Belmont-funded PACMEDY (PAlaeo-Constraints on Monsoon Evolution and Dynamics) project. Aline Govin acknowledges the support of the French national program LEFE/INSU (CircLIG project) and of the Belmont-funded ACCEDE project (ANR-18-BELM-0001-06). Eric Wolff has received funding from the European Research Council under the Horizon 2020 program research and innovation program (grant agreement no. 742224, WACSWAIN). Eric Wolff is also funded by a Royal Society Professorship. Paolo Scussolini acknowledges funding from the NWO (Nederlandse Organisatie voor Wetenschappelijk Onderzoek) under grant ALWOP.164. Emilie Capron acknowledges financial support from the ChronoCli-mate project, funded by the Carlsberg Foundation. Pascale Bra-connot and Masa Kageyama acknowledge the HPC resources of TGCC allocated to the IPSL CMIP6 project by GENCI (Grand Equipment National de Calcul Intensif) under the allocations 2016-A0030107732, 2017-R0040110492, and 2018-R0040110492 (project gencmip6). This work was undertaken in the framework of the LABEX L-IPSL and the IPSL Climate Graduate School, under the 'Investissements d’avenir' program with the reference ANR-11-IDEX-0004-17-EURE-0006. This study benefited from the ES-PRI (Ensemble de Services Pour la Recherche à l’IPSL) computing and data center (https://mesocentre.ipsl.fr, last access: 22 December 2020), which is supported by CNRS, Sorbonne Université, École Polytechnique, and CNES and through national and international projects, including the EU-FP7 Infrastructure project IS-ENES2 (grant no. 312979). Marie Sicard is funded by a scholarship from CEA and 'Convention des Services Climatiques' from IPSL., Laurie Menviel acknowledges support from the Australian Research Council FT180100606. The ACCESS-ESM 1.5 experiments were performed on Raijin at the NCI National Facility at the Australian National University, through awards under the National Computational Merit Allocation Scheme, the Intersect allocation scheme, and the UNSW HPC at NCI Scheme. Qiong Zhang acknowledges the support from the Swedish Research Council (Vetenskapsrådet, grant nos. 2013-06476 and 2017-04232). The EC-Earth simulations are performed on ECMWF’s computing and archive facilities and on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Centre (NSC) partially funded by the Swedish Research Council through grant agreement no. 2016-07213. Weipeng Zheng acknowledges the financial support from National Key R&D Program for Developing Basic Sciences (grant no. 2016YFC1401401), the Strategic Priority Research Program of Chinese Academy of Sciences (grant nos. XDA19060102 and XDB42000000) and the National Natural Science Foundation of China (grant nos. 91958201and 41376002), and the technical support from the National Key Scientific and Technological Infrastructure project 'Earth System Science Numerical Simulator Facility' (EarthLab). Maria Vittoria Guarino and Louise Sime acknowledge the financial support of the NERC research grant NE/P013279/1. Silvana Ramos Buarque and David Salas y Mélia acknowledge Météo-France/DSI for providing computing and data storage resources. Xiaoxu Shi and Christian Stepanek acknowledge computing and data storage resources for the generation of the AWI-ESM-1/AWI-ESM-2 and MPI-ESM-1-2 simulations of Deutsches Klimarechenzentrum (DKRZ) granted by its Scientific Steering Committee (WLA) under project ID ba1066. The Max Planck Institute for Meteorology in Hamburg is acknowledged for development and provision of the MPI-ESM as well as the ECHAM6/JSBACH, which provides the atmosphere and land surface component of AWI-ESM. Gerrit Lohmann acknowledges funding via the Alfred Wegener Institute’s research program PACES2. Christian Stepanek acknowledges funding by the Helmholtz Climate Initiative REKLIM and the Alfred Wegener Institute’s research program PACES2. Xiaoxu Shi acknowledges financial support through the BMBF funded PACMEDY and PalMOD initiatives. Ayako Abe-Ouchi and Ryouta O’ishi acknowledge the financial support from Arctic Challenge for Sustainability (ArCS) Project (grant JPMXD1300000000), Arctic Challenge for Sustainability II (ArCS II) Project (grant no. JPMXD1420318865), JSPS KAKENHI grant 17H06104 and MEXT KAKENHI grant 17H06323, and the support from JAMSTEC for the use of the Earth Simulator supercomputer. Polina A. Morozova was supported by the state assignment project 0148-2019-0009. Evgeny Volodin was supported by RSF grant 20-17-00190., The authors acknowledge QUIGS (Quaternary Interglacials), a working group of Past Global Changes (PAGES), which in turn received support from the US National Science Foundation, Swiss National Science Foundation, Swiss Academy of Sciences, and the Chinese Academy of Sciences. We are grateful to the World Climate Research Programme (WCRP), which, through its Working Group on Coupled Modelling, coordinated and promoted CMIP6., Financial support. Funding of the publication has been supported by the National Center for Atmospheric Research (NCAR), which is a major facility sponsored by the National Science Foundation under cooperative agreement no. 1852977., Water and Climate Risk, Wolff, Eric [0000-0002-5914-8531], Apollo - University of Cambridge Repository, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
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IMPACTS ,010506 paleontology ,010504 meteorology & atmospheric sciences ,Orbital forcing ,sub-01 ,EXPERIMENTAL-DESIGN ,Stratigraphy ,lcsh:Environmental protection ,3705 Geology ,POLAR AMPLIFICATION ,MIDHOLOCENE ,01 natural sciences ,lcsh:Environmental pollution ,Paleoclimatology ,Sea ice ,lcsh:TD169-171.8 ,SDG 14 - Life Below Water ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,TEMPERATURE ,AFRICAN MONSOON ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,13 Climate Action ,Global and Planetary Change ,geography ,Coupled model intercomparison project ,geography.geographical_feature_category ,EARTH SYSTEM MODEL ,CHRONOLOGY AICC2012 ,Northern Hemisphere ,Paleontology ,37 Earth Sciences ,3709 Physical Geography and Environmental Geoscience ,Arctic ice pack ,ANTARCTIC ICE ,13. Climate action ,Climatology ,lcsh:TD172-193.5 ,3701 Atmospheric Sciences ,Climate sensitivity ,Environmental science ,Climate model ,SENSITIVITY - Abstract
The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to the Coupled Model Intercomparison Project (CMIP6) is the Tier 1 Last Interglacial experiment for 127 000 years ago (lig127k), designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models as for the future and following a common experimental protocol. Here we present a first analysis of a multi-model ensemble of 17 climate models, all of which have completed the CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. The equilibrium climate sensitivity (ECS) of these models varies from 1.8 to 5.6 ∘C. The seasonal character of the insolation anomalies results in strong summer warming over the Northern Hemisphere continents in the lig127k ensemble as compared to the CMIP6 piControl and much-reduced minimum sea ice in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than the CMIP6 midHolocene simulations as expected from the larger insolation anomalies at 127 than 6 ka. New synthesis for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and for precipitation over the Northern Hemisphere continents. The model–data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions. The CMIP6–Paleoclimate Modeling Intercomparison Project (PMIP4) lig127k simulations, in combination with the proxy record, improve our confidence in future projections of monsoons, surface temperature, and Arctic sea ice, thus providing a key target for model evaluation and optimization.
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- 2021
6. Large-scale features of Last Interglacial climate: Results from evaluating the lig127k simulations for CMIP6-PMIP4
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Evgeny Volodin, Louise C. Sime, Maria-Vittoria Guarino, Xioaoxu Shi, Masa Kageyama, Esther C. Brady, Paolo Scussolini, Charles Williams, Bette L. Otto-Bliesner, Allegra N. LeGrande, Elizabeth B. Isaacs, Jeremy S. Hoffman, Kerim H. Nisancioglu, Chris Brierley, Anni Zhao, Weipeng Zheng, Nicolas Yeung, Anne de Vernal, Aline Govin, Eric W. Wolff, Katrin J. Meissner, Pascale Braconnot, Yarrow Axford, Laurie Menviel, Gerrit Lohmann, Qiong Zhang, Ryouta O'ishi, Chuncheng Guo, Marie Sicard, Polychronis C Tzedakis, Emilie Capron, Zhonghi Zhang, Robert A. Tomas, Silvana Ramos Buarque, David Salas y Mélia, Jian Cao, Ayako Abe-Ouchi, and National Center for Atmospheric Research [Boulder] (NCAR)
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[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,010506 paleontology ,geography ,geography.geographical_feature_category ,Orbital forcing ,Northern Hemisphere ,Greenland ice sheet ,01 natural sciences ,Arctic ice pack ,13. Climate action ,Climatology ,Paleoclimatology ,[SDE]Environmental Sciences ,Sea ice ,Environmental science ,Climate sensitivity ,Climate model ,0105 earth and related environmental sciences - Abstract
The modeling of paleoclimate, using physically based tools, is increasingly seen as a strong out-of-sample test of the models that are used for the projection of future climate changes. New to CMIP6 is the Tier 1 lig127k experiment, designed to address the climate responses to stronger orbital forcing than the midHolocene experiment, using the same state-of-the-art models and following a common experimental protocol. We present a multi-model ensemble of 17 climate models, all of which (except for two) have also completed the CMIP6 DECK experiments. The Equilibrium Climate Sensitivity (ECS) of these models varies from 2.1 to 5.6 °C. The seasonal character of the insolation anomalies results in strong warming over the Northern Hemisphere (NH) continents in the lig127k ensemble as compared to the piControl in June–July–August and a much-reduced minimum (August–September) summer sea ice extent in the Arctic. The multi-model results indicate enhanced summer monsoonal precipitation and areal extent in the Northern Hemisphere and reductions in the Southern Hemisphere. These responses are greater in the lig127k than midHolocene simulations as expected from the larger insolation anomalies at 127 ka than 6 ka. New syntheses for surface temperature and precipitation, targeted for 127 ka, have been developed for comparison to the multi-model ensemble. The lig127k model ensemble and data reconstructions are in good agreement for summer temperature anomalies over Canada, Scandinavia, and the North Atlantic and precipitation over the Northern Hemisphere continents. The model-data comparisons and mismatches point to further study of the sensitivity of the simulations to uncertainties in the specified boundary conditions and of the uncertainties and sparse coverage in current proxy reconstructions. The CMIP6-PMIP4 lig127k simulations, in combination with the proxy record, have potential implications for confidence in future projections of monsoons, surface temperature, Arctic sea ice, and the stability of the Greenland ice sheet.
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- 2020
7. A multi-model CMIP6 study of Arctic sea ice at 127 ka: Sea ice data compilation and model differences
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Irene Malmierca-Vallet, Maria-Vittoria Guarino, Ruediger Stein, Anne de Vernal, David Schroeder, Marie Sicard, Louise C. Sime, and Masa Kageyama
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geography ,Oceanography ,geography.geographical_feature_category ,Sea ice ,Data compilation ,Arctic ice pack ,Geology - Abstract
The Last interglacial (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models’ representation of climate reconstructions is one of the objectives set up by the Paleoclimate Modelling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 12 climate models in terms of Arctic sea ice. The mean pre-industrial to LIG reduction in minimum sea ice area (SIA) reaches 59% (multi-model mean LIG area is 2.21 mill. km2, compared to 5.85 mill. km2 for the PI), and the range of model results for LIG minimum sea ice area (from 0.02 to 5.65 mill. km2) is larger than for PI (from 4.10 to 8.30 mill. km2). On the other hand there is little change for the maximum sea ice area (which is 12 mill. km2 for both the PI and the LIG, with a standard deviation of 1.04 mill. km2 for PI and 1.21 mill. km2 for LIG). To evaluate the model results we synthesize LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. South of 78oN, in the Atlantic and Nordic seas, the LIG was seasonally ice-free. North of 78oN there are some discrepancies between sea ice reconstructions based on dinocysts/foraminifers/ostracods and IP25: some sites have both seasonal and perennial interpretations based on the same core, but different indicators. Because of the conflicting interpretations it is not possible for any one model to match every data point in our data synthesis, or say whether the Arctic was seasonally ice-free. Drivers for the inter-model differences are: different phasing of the up and down short-wave anomalies over the Arctic ocean, associated with differences in model albedo; possible cloud property differences, in terms of optical depth; LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally we note that inter-comparisons between the LIG simulations, and simulations with moderate CO2 increase (during the transition to high CO2 levels), may yield insight into likely 21C Arctic sea ice changes using these LIG simulations.
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- 2020
8. A sea ice-free Arctic during the Last Interglacial supports fast future loss
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Mark A. Ringer, David Schroeder, Jeff Ridley, Cecilia M. Bitz, Alistair Sellar, Maria-Vittoria Guarino, Julienne Stroeve, Louise C. Sime, Eric W. Wolff, Daniel Feltham, Erica Bree Rosenblum, Irene Malmierca-Vallet, and Eric J. Steig
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geography ,geography.geographical_feature_category ,Oceanography ,Arctic ,Interglacial ,Sea ice ,Geology - Abstract
The Last Interglacial (LIG) is a period of great importance as an analog for future climate change. Global sea level was 6-9 m higher than present. Stronger LIG summertime insolation at high northern latitudes drove Arctic land summer temperatures around 4-5 K higher than during the preindustrial era. Climate-model simulations have previously failed to capture these elevated temperatures. This may be because these models failed to correctly capture LIG sea ice changes.Here, we show that the latest version of the UK Hadley Center coupled ocean-atmosphere climate model (HadGEM3) simulates a much improved Arctic LIG climate, including the observed high temperatures. Improved model physics in HadGEM3, including a sophisticated sea ice melt-pond scheme, results in the first-ever simulation of the complete loss of Arctic sea ice in summer during the LIG.Our ice-free Arctic yields a compelling solution to the long-standing puzzle of what drove LIG Arctic warmth. The LIG simulation result is a new independent constraint on the strength of Arctic sea ice decline in climate-model projections, and provides support for a fast retreat of Arctic summer sea ice in the future.
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- 2020
9. A multi-model CMIP6 study of Arctic sea ice at 127 ka: Sea ice data compilation and model differences
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Masa Kageyama, Cecilia Bitz, Pascale Braconnot, Esther Brady, Matthew A. Chamberlain, Danny Feltham, Chuncheng Guo, Gerrit Lohmann, Katrin Meissner, Laurie Menviel, Polina Morozova, Louise C. Sime, Kerim H. Nisancioglu, Bette Otto-Bliesner, Ryouta O'ishi, Sam Sherriff-Tadano, Julienne Stroeve, Xiaoxu Shi, Bo Sun, Evgeny Volodin, Nicholas Yeung, Qiong Zhang, Marie Sicard, Zhongshi Zhang, Tilo Ziehn, Maria-Vittoria Guarino, Anne de Vernal, David Schroeder, Ruediger Stein, Irene Malmierca-Vallet, and Ayako Abe-Ouchi
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Climatology ,Arctic ,Arctic ice pack ,Interglacial ,Sea ice ,Geology ,Coupled model intercomparison project ,Paleoclimatology ,Cryosphere ,Climate model - Abstract
The Last interglacial (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models’ representation of climate reconstructions is one of the objectives set up by the Paleoclimate Mod-elling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 12 climate models in terms of Arctic sea ice. The mean pre-industrial to LIG reduction in minimum sea ice area (SIA) reaches 59 % (multi-model mean LIG area is 2.21 mill. km2, compared to 5.85 mill. km2 for the PI), and the range of model results for LIG minimum sea ice area (from 0.02 to 5.65 mill. km2) is larger than for PI (from 4.10 to 8.30 mill. km2). On the other hand there is little change for the maximum sea ice area (which is 12 mill. km2 for both the PI and the LIG, with a standard deviation of 1.04 mill. km2 for PI and 1.21 mill. km2 for LIG). To evaluate the model results we synthesize LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. South of 78° N in the Atlantic and Nordic seas the LIG was seasonally ice-free. North of 78° N there are some discrepancies between sea-ice re-constructions based on dinocysts/foraminifers/ostracods and IP25: some sites have both seasonal and perennial interpretations based on the same core, but different indicators. Because of the conflicting interpretations it is not possible for any one model to match every data point in our data synthesis, or say whether the Arctic was seasonally ice-free. Drivers for the inter-model differences are: different phasing of the up and down short-wave anomalies over the Arctic ocean, associated with differences in model albedo; possible cloud property differences, in terms of optical depth; LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally we note that inter-comparisons between the LIG simulations, and simulations with moderate CO2 increase (during the transition to high CO2 levels), may yield insight into likely 21C Arctic sea ice changes using these LIG simulations.
- Published
- 2020
10. Analysing the timing of peak warming and minimum winter sea-ice extent in the Southern Ocean during MIS 5e
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Claire S. Allen, Louise C. Sime, Claus-Dieter Hillenbrand, and Matthew Chadwick
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Marine isotope stage ,010506 paleontology ,Archeology ,010504 meteorology & atmospheric sciences ,δ18O ,Interglacial ,Sediment cores ,01 natural sciences ,Abyssal zone ,Bottom water ,Palaeoceanography ,Ice core ,Sea ice ,14. Life underwater ,Southern Ocean ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Geology ,Oceanography ,13. Climate action ,Benthic zone ,Environmental science - Abstract
The peak of the Last Interglacial, Marine Isotope Stage (MIS) 5e (130–116 ka), provides a valuable ‘process analogue’ for validating the climatic feedbacks and forcings likely active under future anthropogenic warming. Reconstructing exact timings of MIS 5e peak warming and minimum winter sea-ice extent (WSIE) throughout the Southern Ocean (SO) will help to identify the interactions and feedbacks within the ice-ocean system. Here we present a new MIS 5e marine sediment record from the SW Atlantic sector together with 28 published core records (chronologies standardised to the LR04 δ18O benthic stack; Lisiecki and Raymo, 2005) to investigate the timing and sequence of minimum WSIE and peak warming across the SO. Sea-surface temperatures (SSTs) peaked earliest in the Indian (20oE–150oE) and Atlantic (70oW–20oE) sectors, at 128.7 ± 0.8 ka and 127.4 ± 1.1 ka respectively, followed by the Pacific sector (150oE–70oW) at 124.9 ± 3.6 ka. The interval of minimum WSIE for all three sectors occurred within the period from 129–125 ka, consistent with the ∼128 ka sea salt flux minimum in Antarctic ice cores. Minimum WSIE appears to have coincided with peak July insolation at 55 oS, suggesting it could be linked with the mildest winters. The reduced WSIE during MIS 5e would have likely reduced the production of deep- and bottom water masses, inhibiting storage of CO2 in the abyssal ocean and lowering nutrient availability in SO surface waters. Examining a wide spatial range of proxy records for MIS 5e is a critical step forward in understanding climatic interactions and processes that will be active under warmer global temperatures.
- Published
- 2020
11. Machine dependence as a source of uncertainty in climate models: The HadGEM3-GC3.1 CMIP Preindustrial simulation
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David Schroeder, Maria-Vittoria Guarino, Louise C. Sime, Rosalyn Hatcher, and Grenville M. S. Lister
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geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Longwave ,Magnitude (mathematics) ,Flux ,010502 geochemistry & geophysics ,Supercomputer ,01 natural sciences ,13. Climate action ,Climatology ,Sea ice ,Environmental science ,Climate model ,Southern Hemisphere ,0105 earth and related environmental sciences ,Teleconnection - Abstract
When the same weather or climate simulation is run on different High Performance Computing (HPC) platforms, model outputs may not be identical for a given initial condition. While the role of HPC platforms in delivering better climate projections is often discussed in literature, attention is mainly focused on scalability and performance rather than on the impact of machine-dependent processes on the numerical solution. At the same time, machine dependence is an overlooked source of uncertainty when it comes to discussing the model spread observed within the Coupled Model Intercomparison Projects (CMIP). Here we investigate the impact of machine dependence on model results and quantify, for a selected case study, the magnitude of the uncertainty. We consider the Preindustrial (PI) simulation prepared by the UK Met Office for the forthcoming CMIP6. We compare key climate variables between PI control simulations run on the UK Met Office supercomputer and the ARCHER HPC platform. Discrepancies strongly depend on the timescale. Decadal means show substantial differences of up to 0.2 °C for global mean air temperature, 1 W/m2 for TOA outgoing longwave flux and 1.2 million km2 for Southern Hemisphere sea ice area. However, on multi-centennial timescales the differences are not significant and the long-term statistics of the two runs are similar. Differences between the two simulations can be linked to variations in the strongest modes of climate variability. In the Southern Hemisphere, this results in large SST anomalies where ENSO teleconnection patterns are expected that can reach 0.6 °C (and SNR > 1) even on centennial timescales.
- Published
- 2019
12. Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
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Rachael H. Rhodes, Peter O. Hopcroft, and Louise C. Sime
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010504 meteorology & atmospheric sciences ,F800 ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Ice shelf ,Paleothermometer ,Earth, Atmospheric, and Planetary Sciences ,Arctic ,Ice core ,paleoclimate ,Paleoclimatology ,Sea ice ,Glacial period ,Meltwater ,0105 earth and related environmental sciences ,geography ,Multidisciplinary ,geography.geographical_feature_category ,abrupt warmings ,sea ice ,climate change ,13. Climate action ,Physical Sciences ,Ice sheet ,Geology - Abstract
Significance The Dansgaard–Oeschger events contained in Greenland ice cores constitute the archetypal record of abrupt climate change. An accurate understanding of these events hinges on interpretation of Greenland records of oxygen and nitrogen isotopes. We present here the important results from a suite of modeled Dansgaard–Oeschger events. These simulations show that the change in oxygen isotope per degree of warming becomes smaller during larger events. Abrupt reductions in sea ice also emerge as a strong control on ice core oxygen isotopes because of the influence on both the moisture source and the regional temperature increase. This work confirms the significance of sea ice for past abrupt warming events., Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atmospheric circulation, and meltwater changes. DO event temperature reconstructions depend on the stable water isotope (δ18O) and nitrogen isotope measurements from Greenland ice cores: interpretation of these measurements holds the key to understanding the nature of DO events. Here, we demonstrate the primary importance of sea ice as a control on Greenland ice core δ18O: 95% of the variability in δ18O in southern Greenland is explained by DO event sea ice changes. Our suite of DO events, simulated using a general circulation model, accurately captures the amplitude of δ18O enrichment during the abrupt DO event onsets. Simulated geographical variability is broadly consistent with available ice core evidence. We find an hitherto unknown sensitivity of the δ18O paleothermometer to the magnitude of DO event temperature increase: the change in δ18O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality.
- Published
- 2019
13. Simulating the Last Interglacial Greenland stable water isotope peak: the role of Arctic sea ice changes
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Max D. Holloway, Emilie Capron, Bo Møllesøe Vinther, Irene Malmierca-Vallet, Louise C. Sime, Julia Tindall, and Paul J. Valdes
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010506 paleontology ,Archeology ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,δ18O ,Northern Hemisphere ,Geology ,Present day ,01 natural sciences ,Arctic ice pack ,Oceanography ,Ice core ,13. Climate action ,Interglacial ,Sea ice ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
Last Interglacial (LIG), stable water isotope values (δ18O) measured in Greenland deep ice cores are at least 2.5‰ higher compared to the present day. Previous isotopic climate simulations of the LIG do not capture the observed Greenland δ18O increases. Here, we use the isotope-enabled HadCM3 (UK Met Office coupled atmosphere-ocean general circulation model) to investigate whether a retreat of Northern Hemisphere sea ice was responsible for this model-data disagreement. Our results highlight the potential significance of sea ice changes on the LIG Greenland isotopic maximum. Sea ice loss in combination with increased sea surface temperatures, over the Arctic, affect δ18O: water vapour enriched in heavy isotopes and a shorter distillation path may both increase δ18O values over Greenland. We show, for the first time, that simulations of the response to Arctic sea ice reduction are capable of producing the likely magnitude of LIG δ18O increases at NEEM, NGRIP, GIPS2 and Camp Century ice core sites. However, we may underestimate δ18O changes at the Renland, DYE3 and GRIP ice core locations. Accounting for possible ice sheet changes is likely to be required to produce a better fit to the LIG ice core δ18O values.
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- 2018
14. Holocene dynamics of the Southern Hemisphere westerly winds and possible links to CO2 outgassing
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Louise C. Sime, Sarah J. Davies, Dominic A. Hodgson, Stephen Roberts, Christoph Florian Butz, Krystyna M. Saunders, Martin Grosjean, Bianca B. Perren, and Wim Van Nieuwenhuyze
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geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Carbon sink ,Westerlies ,910 Geography & travel ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,Current (stream) ,Outgassing ,550 Earth sciences & geology ,Sea ice ,General Earth and Planetary Sciences ,Upwelling ,Environmental science ,Southern Hemisphere ,Holocene ,0105 earth and related environmental sciences - Abstract
The Southern Hemisphere westerly winds (SHW) play an important role in regulating the capacity of the Southern Ocean carbon sink. They modulate upwelling of carbon-rich deep water and, with sea ice, determine the ocean surface area available for air–sea gas exchange. Some models indicate that the current strengthening and poleward shift of these winds will weaken the carbon sink. If correct, centennial- to millennial-scale reconstructions of the SHW intensity should be linked with past changes in atmospheric CO2, temperature and sea ice. Here we present a 12,300-year reconstruction of wind strength based on three independent proxies that track inputs of sea-salt aerosols and minerogenic particles accumulating in lake sediments on sub-Antarctic Macquarie Island. Between about 12.1 thousand years ago (ka) and 11.2 ka, and since about 7 ka, the wind intensities were above their long-term mean and corresponded with increasing atmospheric CO2. Conversely, from about 11.2 to 7.2 ka, the wind intensities were below their long-term mean and corresponded with decreasing atmospheric CO2. These observations are consistent with model inferences of enhanced SHW contributing to the long-term outgassing of CO2 from the Southern Ocean. The strength of the Southern Hemisphere westerly winds varied throughout the Holocene, according to a reconstruction from lake sediments, with periods of stronger winds coincident with higher atmospheric CO2 levels.
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- 2018
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15. The Spatial Structure of the 128 ka Antarctic Sea Ice Minimum
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Claus-Dieter Hillenbrand, Claire S. Allen, Eric W. Wolff, Louise C. Sime, Paul J. Valdes, Pete Bunch, Max D. Holloway, Wolff, Eric [0000-0002-5914-8531], and Apollo - University of Cambridge Repository
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010506 paleontology ,last interglacial ,010504 meteorology & atmospheric sciences ,ice cores ,Antarctic ice sheet ,Antarctic sea ice ,01 natural sciences ,Sea ice ,Cryosphere ,14. Life underwater ,0105 earth and related environmental sciences ,sediment cores ,geography ,geography.geographical_feature_category ,128 ka ,15. Life on land ,Arctic ice pack ,sea ice ,Geophysics ,Oceanography ,Fast ice ,13. Climate action ,Sea ice thickness ,General Earth and Planetary Sciences ,Antarctic ,Ice sheet ,Geology - Abstract
We compare multi-ice core data with δ18O model output for the early last interglacial Antarctic sea ice minimum. The spatial pattern of δ18O across Antarctica is sensitive to the spatial pattern of sea ice retreat. Local sea ice retreat increases the proportion of winter precipitation, depleting δ18O at ice core sites. However, retreat also enriches δ18O because of the reduced source-to-site distance for atmospheric vapor. The joint overall effect is for δ18O to increase as sea ice is reduced. Our data-model comparison indicates a winter sea ice retreat of 67, 59, and 43% relative to preindustrial in the Atlantic, Indian, and Pacific sectors of the Southern Ocean. A compilation of Southern Ocean sea ice proxy data provides weak support for this reconstruction. However, most published marine core sites are located too far north of the 128,000 years B.P. sea ice edge, preventing independent corroboration for this sea ice reconstruction. Plain Language Summary The Antarctic isotope and temperature maximum, which occurred approximately 128,000 years before present (B.P.) during the warmer than present last interglacial period, is associated with a major retreat of Antarctic sea ice. Understanding the details of this major sea ice retreat is crucial in order to understand the sensitivity of the Southern Hemisphere sea ice system and to evaluate the performance of climate model simulations in response to future warming. This work uses a multi-ice and ocean core data-model evaluation to assess the magnitude and spatial pattern of this sea ice retreat. Our results suggest that sea ice retreat was greatest in the Atlantic and Indian sectors of the Southern Ocean and less in the Pacific sector. These results may have had serious implications for the stability of marine terminating glaciers around the Antarctic Ice Sheet and their contribution to the last interglacial sea level rise. These results also support a hypothesized slowdown in northward ocean heat transport during the early last interglacial.
- Published
- 2017
16. Simulating the 128-ka Antarctic Climate Response to Northern Hemisphere Ice Sheet Melting Using the Isotope-Enabled HadCM3
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Joy S. Singarayer, Paul J. Valdes, Max D. Holloway, Julia Tindall, and Louise C. Sime
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010506 paleontology ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Northern Hemisphere ,01 natural sciences ,Sea surface temperature ,Geophysics ,Oceanography ,Ice core ,13. Climate action ,Interglacial ,Paleoclimatology ,Sea ice ,General Earth and Planetary Sciences ,14. Life underwater ,Ice sheet ,Meltwater ,Geology ,0105 earth and related environmental sciences - Abstract
Warmer than present Antarctic and Southern Ocean temperatures during the last interglacial, approximately 128,000 years ago, have been attributed to changes in north-south ocean heat transport, causing opposing hemispheric temperature anomalies. We investigate the magnitude of Antarctic warming and Antarctic ice core isotopic enrichment in response to Northern Hemisphere meltwater input during the early last interglacial. A 1,600 year HadCM3 simulation driven by 0.25 Sv of meltwater input reproduces 50-60 % of the peak Southern Ocean summer sea surface temperature anomaly, sea ice retreat and ice core isotope enrichment. We also find a robust increase in the proportion of cold season precipitation during the last interglacial, leading to lower isotopic values at the Antarctic ice core sites. These results suggest that a HadCM3 simulation including 0.25 Sv for 3,000-4,000 years would reconcile the last interglacial observations, providing a potential solution for the last interglacial 'missing heat' problem.
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- 2018
17. Sea ice led to poleward-shifted winds at the Last Glacial Maximum: the influence of state dependency on CMIP5 and PMIP3 models
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Dominic A. Hodgson, Bianca B. Perren, Claire S. Allen, Agatha M. de Boer, Louise C. Sime, Thomas J. Bracegirdle, and Stephen Roberts
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010504 meteorology & atmospheric sciences ,lcsh:Environmental protection ,Stratigraphy ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,lcsh:Environmental pollution ,Sea ice ,lcsh:TD169-171.8 ,Glacial period ,14. Life underwater ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Drift ice ,Global and Planetary Change ,Jet (fluid) ,geography ,geography.geographical_feature_category ,Paleontology ,Westerlies ,Last Glacial Maximum ,Jet stream ,13. Climate action ,Climatology ,lcsh:TD172-193.5 ,Interglacial ,Geology - Abstract
Latitudinal shifts in the Southern Ocean westerly wind jet could drive changes in the glacial to interglacial ocean CO2 inventory. However, whilst CMIP5 model results feature consistent future-warming jet shifts, there is considerable disagreement in deglacial-warming jet shifts. We find here that the dependence of pre-industrial (PI) to Last Glacial Maximum (LGM) jet shifts on PI jet position, or state dependency, explains less of the shifts in jet simulated by the models for the LGM compared with future-warming scenarios. State dependence is also weaker for intensity changes, compared to latitudinal shifts in the jet. Winter sea ice was considerably more extensive during the LGM, along with state dependence, changes in surface heat fluxes due this sea ice change probably had a large impact on the jet. Models which both simulate realistically large expansions in sea ice and feature PI jets which are south of 50 °S, show an increase in wind speed around 55 °S, and can show a poleward shift in the jet between the PI and the LGM. However models with the PI jet positioned equatorwards of around 47 °S do not show this response: the sea ice edge is too far from the jet for it to respond. In models with accurately positioned PI jets; a +1° difference in the latitude of the sea ice edge tends to be associated with a −0.85° shift in the 850 hPa jet. However, it seems that around 5° of expansion of LGM sea ice is necessary to hold the jet in its PI position. Since observational data supports an expansion of more than 5°, this result suggests that a slight poleward shift and intensification, was the most likely jet change between the PI and the LGM. Without the effect of sea ice, models simulated polewards shifted westerlies in warming climates and equatorward shifted westerlies in colder climates. However, the feedback of sea ice counters and reverses the equatorward trend in cooler climates so that the LGM winds were more likely to have also been shifted slightly poleward.
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- 2016
18. Reconstructing paleosalinity from δ18O: Coupled model simulations of the Last Glacial Maximum, Last Interglacial and Late Holocene
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Paul J. Valdes, Joy S. Singarayer, Max D. Holloway, Julia Tindall, and Louise C. Sime
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Archeology ,010504 meteorology & atmospheric sciences ,010502 geochemistry & geophysics ,Paleosalinity ,01 natural sciences ,Last Interglacial ,Paleoceanography ,Isotopes ,Sea ice ,14. Life underwater ,Water cycle ,Ecology, Evolution, Behavior and Systematics ,Holocene ,Oxygen-18 ,0105 earth and related environmental sciences ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,Last Glacial Maximum ,Ocean current ,Geology ,6. Clean water ,13. Climate action ,Climatology ,Interglacial - Abstract
Reconstructions of salinity are used to diagnose changes in the hydrological cycle and ocean circulation. A widely used method of determining past salinity uses oxygen isotope (δOw) residuals after the extraction of the global ice volume and temperature components. This method relies on a constant relationship between δOw and salinity throughout time. Here we use the isotope-enabled fully coupled General Circulation Model (GCM) HadCM3 to test the application of spatially and time-independent relationships in the reconstruction of past ocean salinity. Simulations of the Late Holocene (LH), Last Glacial Maximum (LGM), and Last Interglacial (LIG) climates are performed and benchmarked against existing compilations of stable oxygen isotopes in carbonates (δOc), which primarily reflect δOw and temperature. We find that HadCM3 produces an accurate representation of the surface ocean δOc distribution for the LH and LGM. Our simulations show considerable variability in spatial and temporal δOw-salinity relationships. Spatial gradients are generally shallower but within ~50% of the actual simulated LH to LGM and LH to LIG temporal gradients and temporal gradients calculated from multi-decadal variability are generally shallower than both spatial and actual simulated gradients. The largest sources of uncertainty in salinity reconstructions are found to be caused by changes in regional freshwater budgets, ocean circulation, and sea ice regimes. These can cause errors in salinity estimates exceeding 4 psu. Our results suggest that paleosalinity reconstructions in the South Atlantic, Indian and Tropical Pacific Oceans should be most robust, since these regions exhibit relatively constant δOw-salinity relationships across spatial and temporal scales. Largest uncertainties will affect North Atlantic and high latitude paleosalinity reconstructions. Finally, the results show that it is difficult to generate reliable salinity estimates for regions of dynamic oceanography, such as the North Atlantic, without additional constraints.
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- 2016
19. Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse
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Julia Tindall, Max D. Holloway, Joy S. Singarayer, Louise C. Sime, Pete Bunch, and Paul J. Valdes
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geography ,Multidisciplinary ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Science ,General Physics and Astronomy ,Antarctic ice sheet ,General Chemistry ,Antarctic sea ice ,010502 geochemistry & geophysics ,01 natural sciences ,Arctic ice pack ,General Biochemistry, Genetics and Molecular Biology ,Article ,Ice-sheet model ,Oceanography ,Ice core ,13. Climate action ,Sea ice ,Cryosphere ,Ice sheet ,Geology ,0105 earth and related environmental sciences - Abstract
Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming., The peak in Antarctic ice core isotope values, 128,000 years before present, was concurrent with a significantly warmer-than-present Antarctic climate. Here, the authors show that this isotope maximum was associated with a major retreat of sea ice and not a collapse of the West Antarctic Ice Sheet.
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- 2015
20. Warm climate isotopic simulations: What do we learn about interglacial signals in Greenland ice cores?
- Author
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Camille Risi, Emilie Capron, Jesper Sjolte, Eric W. Wolff, Louise C. Sime, Valérie Masson-Delmotte, Julia Tindall, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado [Boulder]-National Oceanic and Atmospheric Administration (NOAA), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), School of Earth and Environment [Leeds] (SEE), University of Leeds, Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), GeoBiosphere Science Centre, Quaternary Sciences, Lund University, Slvegatan 12, SE-223 62 Lund, Sweden, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
- Subjects
010506 paleontology ,Archeology ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Glaciology ,Geology ,Antarctic sea ice ,01 natural sciences ,Arctic ice pack ,Ice core ,13. Climate action ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,Climatology ,Sea ice thickness ,Interglacial ,Sea ice ,Cryosphere ,14. Life underwater ,[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
International audience; Measurements of Last Interglacial stable water isotopes in ice cores show that central Greenland d18O increased by at least 3‰ compared to present day. Attempting to quantify the Greenland interglacial temperature change from these ice core measurements rests on our ability to interpret the stable water isotope content of Greenland snow. Current orbitally driven interglacial simulations do not show d18O or temperature rises of the correct magnitude, leading to difficulty in using only these experiments to inform our understanding of higher interglacial d18O. Here, analysis of greenhouse gas warmed simulations from two isotope-enabled general circulation models, in conjunction with a set of Last Interglacial sea surface observations, indicates a possible explanation for the interglacial d18O rise. A reduction in the winter time sea ice concentration around the northern half of Greenland, together with an increase in sea surface temperatures over the same region, is found to be sufficient to drive a >3‰ interglacial enrichment in central Greenland snow. Warm climate d18O and dD in precipitation falling on Greenland are shown to be strongly influenced by local sea surface condition changes: local sea surface warming and a shrunken sea ice extent increase the proportion of water vapour from local (isotopically enriched) sources, compared to that from distal (isotopically depleted) sources. Precipitation intermittency changes, under warmer conditions, leads to geographical variability in the d18O against temperature gradients across Greenland. Little sea surface warming around the northern areas of Greenland leads to low d18O against temperature gradients (0.1-0.3‰ per °C), whilst large sea surface warmings in these regions leads to higher gradients (0.3-0.7‰ per °C). These gradients imply a wide possible range of present day to interglacial temperature increases (4 to >10 °C). Thus, we find that uncertainty about local interglacial sea surface conditions, rather than precipitation intermittency changes, may lead to the largest uncertainties in interpreting temperature from Greenland ice cores. We find that interglacial sea surface change observational records are currently insufficient to enable discrimination between these different d18O against temperature gradients. In conclusion, further information on interglacial sea surface temperatures and sea ice changes around northern Greenland should indicate whether +5 °C during the Last Interglacial is sufficient to drive the observed ice core d18O increase, or whether a larger temperature increases or ice sheet changes are also required to explain the ice core observations.
- Published
- 2013
21. Sensitivity of interglacial Greenland temperature and δ18O to orbital and CO2 forcing: climate simulations and ice core data
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A. Landais, Louise C. Sime, V. Masson-Delmotte, Q. Lejeune, J. Sjolte, Bo Møllesøe Vinther, Camille Risi, D. Swingedouw, M. Kageyama, P. Braconnot, George R. Hoffmann, and J. Jouzel
- Subjects
Ice-sheet model ,geography ,geography.geographical_feature_category ,Ice core ,Ice stream ,Climatology ,Interglacial ,Sea ice ,Cryosphere ,Ice sheet ,Atmospheric sciences ,Arctic ice pack ,Geology - Abstract
The sensitivity of interglacial Greenland temperature to orbital and CO2 forcing is investigated using the NorthGRIP ice core data and coupled ocean-atmosphere IPSL-CM4 model simulations. These simulations were conducted in response to different interglacial orbital configurations, and to increased CO2 concentrations. These different forcings cause very distinct simulated seasonal and latitudinal temperature and water cycle changes, limiting the analogies between the last interglacial and future climate. However, the IPSL-CM4 model shows similar magnitudes of Arctic summer warming and climate feedbacks in response to 2 × CO2 and orbital forcing of the last interglacial period (126 000 yr ago). The IPSL model produces a remarkably linear relationship between top of atmosphere incoming summer solar radiation and simulated changes in summer and annual mean central Greenland temperature. This contrasts with the stable isotope record from the Greenland ice cores, showing a multi-millennial lagged response to summer insolation. During the early part of interglacials, the observed lags may be explained by ice sheet-ocean feedbacks linked with changes in ice sheet elevation and the impact of meltwater on ocean circulation, as investigated with sensitivity studies. A quantitative comparison between ice core data and climate simulations requires to explore the stability of the stable isotope – temperature relationship. Atmospheric simulations including water stable isotopes have been conducted with the LMDZiso model under different boundary conditions. This set of simulations allows to calculate a temporal Greenland isotope-temperature slope (0.3–0.4 ‰ per °C) during warmer than present Arctic climates, in response to increased CO2, increased ocean temperature and orbital forcing. This temporal slope appears twice as small as the modern spatial gradient and is consistent with other ice core estimates. A preliminary comparison with other model results implies that other mechanisms could also play a role. This suggests that further simulations and detailed inter-model comparisons are also likely to be of benefit. Comparisons with Greenland ice core stable isotope data reveals that IPSL/LMDZiso simulations strongly underestimate the amplitude of the ice core signal during the last interglacial, which could reach +8–10 °C at fixed-elevation. While the model-data mismatch may result from missing positive feedbacks (e.g. vegetation), it could also be explained by a reduced elevation of the central Greenland ice sheet surface by 300–400 m.
- Published
- 2011
22. A comparison of the present and last interglacial periods in six Antarctic ice cores
- Author
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Ryu Uemura, Catherine Ritz, Elisabeth Schlosser, Amaelle Landais, David Pollard, Jean Jouzel, Gerhard Krinner, Barbara Stenni, Valérie Masson-Delmotte, Hideaki Motoyama, Hans Oerter, K. Pol, Alexey A. Ekaykin, Harald Sodemann, Louise C. Sime, Massimo Frezzotti, Françoise Vimeux, Hubert Gallée, D. Buiron, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), CLIPS, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Arctic and Antarctic Research Institute (AARI), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), Italian National agency for new technologies, Energy and sustainable economic development [Frascati] (ENEA), Research Organization of Information and Systems, National Institute of Polar Research [Tokyo] (NiPR), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Earth and Environmental Systems Institute, Pennsylvania State University (Penn State), Penn State System-Penn State System, EDGe, Institute of Meteorology and Geophysics [Innsbruck], Leopold Franzens Universität Innsbruck - University of Innsbruck, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Norwegian Institute for Air Research (NILU), Dipartimento di Scienze Geologiche [Trieste], Università degli studi di Trieste = University of Trieste, Department of Chemistry, Biology and Marine Science, University of the Ryukyus [Okinawa], Hydrosciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), WaterSIP, HOLOCLIP, PolarCLIMATE programme, European Project: 39423,FP6-SUSTDEV,EPICA-MIS, Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), College of Earth and Mineral Sciences, University of Innsbruck, Università degli studi di Trieste, Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Masson-Delmotte, V., Buiron, D., Ekaykin, A., Frezzotti, M., Gallee, H., Jouzel, J., Krinner, G., Landais, A., Motoyama, H., Oerter, H., Pol, K., Pollard, D., Ritz, C., Schlosser, E., Sime, L. C., Sodemann, H., Stenni, B., Uemura, R., Vimeux, F., Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-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)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Masson Delmotte, V., Gallée, H., and Stenni, Barbara
- Subjects
010506 paleontology ,010504 meteorology & atmospheric sciences ,Glaciology ,Stratigraphy ,Ice stream ,lcsh:Environmental protection ,Ice core ,Antarctic sea ice ,Eemian ,010502 geochemistry & geophysics ,01 natural sciences ,precipitation intermittency ,Meteorology and Climatology ,lcsh:Environmental pollution ,Sea ice ,Cryosphere ,Ice cores ,East Antarctica ,isotopic records ,Holocene ,moisture sources ,elevation changes ,lcsh:TD169-171.8 ,[SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,isotopic record ,European Project for Ice Coring in Antarctica ,Paleontology ,15. Life on land ,Ice-sheet model ,Chemistry ,13. Climate action ,Climatology ,lcsh:TD172-193.5 ,moisture source ,Ice sheet ,Geology - Abstract
We compare the present and last interglacial periods as recorded in Antarctic water stable isotope records now available at various temporal resolutions from six East Antarctic ice cores: Vostok, Taylor Dome, EPICA Dome C (EDC), EPICA Dronning Maud Land (EDML), Dome Fuji and the recent TALDICE ice core from Talos Dome. We first review the different modern site characteristics in terms of ice flow, meteorological conditions, precipitation intermittency and moisture origin, as depicted by meteorological data, atmospheric reanalyses and Lagrangian moisture source diagnostics. These different factors can indeed alter the relationships between temperature and water stable isotopes. Using five records with sufficient resolution on the EDC3 age scale, common features are quantified through principal component analyses. Consistent with instrumental records and atmospheric model results, the ice core data depict rather coherent and homogenous patterns in East Antarctica during the last two interglacials. Across the East Antarctic plateau, regional differences, with respect to the common East Antarctic signal, appear to have similar patterns during the current and last interglacials. We identify two abrupt shifts in isotopic records during glacial inception at TALDICE and EDML, likely caused by regional sea ice expansion. These regional differences are discussed in terms of moisture origin and in terms of past changes in local elevation histories which are compared to ice sheet model results. Our results suggest that, for coastal sites, elevation changes may contribute significantly to inter-site differences. These elevation changes may be underestimated by current ice sheet models.
- Published
- 2011
23. Greenland deglaciation puzzles
- Author
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Louise C. Sime
- Subjects
Ice-sheet model ,geography ,Multidisciplinary ,geography.geographical_feature_category ,Oceanography ,Greenland ice core project ,13. Climate action ,Sea ice ,Cryosphere ,Greenland ice sheet ,Antarctic sea ice ,Ice sheet ,Arctic ice pack - Abstract
About 23,000 years ago, the southern margins of the great Northern Hemisphere ice sheets across Europe and North America began to melt. The melt rate accelerated ∼20,000 years ago, and global sea level eventually rose by ∼130 m as meltwater flowed into the oceans. Ice cores from the Greenland and Antarctic ice sheets show the rise in atmospheric CO2 concentrations that accompanied this shift in global ice volume and climate. However, discrepancies in the temperature reconstructions from these cores have raised questions about the long-term relationship between atmospheric CO2 concentrations and Arctic temperature. On page 1177 of this issue, Buizert et al. ( 1 ) report temperature reconstructions from three locations on the Greenland ice sheet that directly address these problems.
- Published
- 2014
24. Ice core evidence for a 20th century decline in sea ice in the Bellingshausen Sea, Antarctica
- Author
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Robert Mulvaney, Thomas J. Bracegirdle, Joseph R. McConnell, Elizabeth R. Thomas, Louise C. Sime, Nerilie J. Abram, and Alberto J. Aristarain
- Subjects
Arctic sea ice decline ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Glaciology ,Ice stream ,Soil Science ,Antarctic sea ice ,Aquatic Science ,010502 geochemistry & geophysics ,Oceanography ,01 natural sciences ,Atmospheric Sciences ,Geochemistry and Petrology ,Earth and Planetary Sciences (miscellaneous) ,Sea ice ,Cryosphere ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology ,Drift ice ,geography ,geography.geographical_feature_category ,Ecology ,Paleontology ,Forestry ,Arctic ice pack ,Chemistry ,Geophysics ,13. Climate action ,Space and Planetary Science ,Ice sheet - Abstract
[1] This study uses ice core methanesulphonic acid (MSA) records from the Antarctic Peninsula, where temperatures have been warming faster than anywhere else in the Southern Hemisphere, to reconstruct the 20th century history of sea ice change in the adjacent Bellingshausen Sea. Using satellite‐derived sea ice and meteorological data, we show that ice core MSA records from this region are a reliable proxy for regional sea ice change, with years of increased winter sea ice extent recorded by increased ice core MSA concentrations. Our reconstruction suggests that the satellite‐observed sea ice decline in the Bellingshausen Sea during recent decades is part of a long‐term regional trend that has occurred throughout the 20th century. The long‐term perspective on sea ice in the Bellingshausen Sea is consistent with evidence of 20th century warming on the Antarctic Peninsula and may reflect a progressive deepening of the Amundsen Sea Low due to increasing greenhouse gas concentrations and, more recently, stratospheric ozone depletion. As a first‐order estimate, our MSA‐based reconstruction suggests that sea ice in the Bellingshausen Sea has retreated southward by ∼0.7° during the 20th century. Comparison with other 20th century sea ice observations, reconstructions, and model simulations provides a coherent picture of Antarctic sea ice decline during the 20th century, although with regional‐scale differences evident in the timing and magnitude of this sea ice decline. This longer‐term perspective contrasts with the small overall increase in Antarctic sea ice that is observed in post‐1979 satellite data.
- Published
- 2010
25. Changes in environment over the last 800,000 years from chemical analysis of the EPICA Dome C ice core
- Author
-
Thomas F. Stocker, Marie-Louise Siggaard-Andersen, Patrik R Kaufmann, Emiliano Castellano, Carlo Barbante, Urs Ruth, Ulf Jonsell, Silvia Becagli, Torbjörn Karlin, Louise C. Sime, Fabrice Lambert, Robert Mulvaney, Mirko Severi, Dietmar Wagenbach, Roberto Udisti, Matthias Bigler, Margareta Hansson, Eric W. Wolff, M. de Angelis, Manuel A. Hutterli, Rita Traversi, Anna Wegner, Claude F Boutron, Regine Röthlisberger, Geneviève C Littot, Felix Fundel, Hubertus Fischer, Birthe Twarloh, Urs Federer, Jørgen Peder Steffensen, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Institute for the Dynamics of Environmental Processes-CNR, Department of Environmental Sciences, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Department of Chemistry, Centre for Ice and Climate [Copenhagen], Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), CHANG (CHANG), Laboratoire d'étude des transferts en hydrologie et environnement (LTHE), Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Department of Physical Geography and Quaternary Geology, Stockholm University, Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern]-Universität Bern [Bern], Abteilung Klinische Sozialmedizin, Berufs- und Umweltdermatologie, Universität Heidelberg [Heidelberg], Institut für Umweltphysik [Heidelberg], Department of Bentho-pelagic processes, European Project: 39423,FP6-SUSTDEV,EPICA-MIS, University Milano-Bicocca, CHANG, Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Institut für Meteorologie und Klimaforschung (IMK), Karlsruher Institut für Technologie (KIT), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), and Universität Heidelberg [Heidelberg] = Heidelberg University
- Subjects
Drift ice ,Archeology ,Global and Planetary Change ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Ice stream ,Geology ,Antarctic sea ice ,010502 geochemistry & geophysics ,01 natural sciences ,Arctic ice pack ,Oceanography ,Ice core ,13. Climate action ,Sea ice ,Cryosphere ,[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology ,14. Life underwater ,Ice sheet ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
International audience; The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and sequential ice. Numerous chemical species have been measured along the length of the cores. Here we concentrate on interpreting the main low-resolution patterns of major ions. We extend the published record for non-sea-salt calcium, sea-salt sodium and non-sea-salt sulfate flux to 800 ka. The non-sea-salt calcium record confirms that terrestrial dust originating from South America closely mirrored Antarctic climate, both at orbital and millennial timescales. A major cause of the main trends is most likely climate in southern South America, which could be sensitive to subtle changes in atmospheric circulation. Sea-salt sodium also follows temperature, but with a threshold at low temperature. We re-examine the use of sodium as a sea ice proxy, concluding that it is probably reflecting extent, with high salt concentrations reflecting larger ice extents. With this interpretation, the sodium flux record indicates low ice extent operating as an amplifier in warm interglacials. Non-sea-salt sulfate flux is almost constant along the core, confirming the lack of change in marine productivity (for sulfur-producing organisms) in the areas of the Southern Ocean contributing to the flux at Dome C. For the first time we also present long records of reversible species such as nitrate and chloride, and show that the pattern of post-depositional losses described for shallower ice is maintained in older ice. It appears possible to use these concentrations to constrain snow accumulation rates in interglacial ice at this site, and the results suggest a possible correction to accumulation rates in one early interglacial. Taken together the chemistry records offer a number of constraints on the way the Earth system combined to give the major climate fluctuations of the late Quaternary period.
- Published
- 2010
26. Antarctic interglacial climate variability and implications for changes in ice sheet topography
- Author
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M. Siddall, K. Pol, H. Goosse, Valérie Masson-Delmotte, Barbara Stenni, Sarah L. Bradley, Louise C. Sime, and Emilie Capron
- Subjects
Ice-sheet model ,geography ,geography.geographical_feature_category ,Oceanography ,Ice core ,Ice stream ,Interglacial ,Sea ice ,Cryosphere ,Antarctic sea ice ,Ice sheet ,Geology - Published
- 2013
27. Sea surface temperature controls on warm climate water isotopes in Greenland ice cores
- Author
-
Valerie Masson-Delmotte, Jesper Sjolte, Louise C. Sime, and Camille Risi
- Subjects
geography ,Brinicle ,Oceanography ,Ice cap climate ,geography.geographical_feature_category ,Sea ice thickness ,Sea ice ,Cryosphere ,Antarctic sea ice ,Ice sheet ,Arctic ice pack ,Geology - Published
- 2013
28. Summer sea-ice variability on the Antarctic margin during the last glacial period reconstructed from snow petrel (Pagodroma nivea) stomach-oil deposits
- Author
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Gerhard Kuhn, Stewart S. R. Jamieson, Darren R. Gröcke, Sonja Berg, Dominic A. Hodgson, Martin D. West, Richard A. Phillips, Ian W. Croudace, Louise C. Sime, Thomas Wardley, Erin L McClymont, Michael J. Bentley, and Charlotte L. Spencer-Jones
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Marine isotope stage ,geography ,Global and Planetary Change ,geography.geographical_feature_category ,Krill ,biology ,Stratigraphy ,Paleontology ,Antarctic sea ice ,15. Life on land ,Snow ,biology.organism_classification ,Oceanography ,Ice core ,Snow petrel ,13. Climate action ,Sea ice ,Glacial period ,14. Life underwater ,Geology - Abstract
Antarctic sea ice is a critical component of the climate system, affecting a range of physical and biogeochemical feedbacks, and supporting unique ecosystems. During the last glacial stage, Antarctic sea ice was more extensive than today, but uncertainties in geological (marine sediments), glaciological (ice core), and climate model reconstructions of past sea-ice extent continue to limit our understanding of its role in the Earth system. Here, we present a novel archive of past sea-ice environments from regurgitated stomach oils of snow petrels (Pagodroma nivea), preserved at nesting sites in Dronning Maud Land, Antarctica. We show that by combining information from fatty acid distributions and their stable carbon isotope ratios with measurements of bulk carbon and nitrogen stable isotopes and trace metal data, it is possible to reconstruct changing snow petrel diet within Marine Isotope Stage 2 (ca. 22.6–28.8 cal. kyr BP). We show that, as today, a mixed diet of krill and fish characterises much of the record. However, between 25.7–26.8 cal. kyr BP signals of krill almost disappear. By linking dietary signals in the stomach-oil deposits to modern feeding habits and foraging ranges, we infer the use by snow petrels of open water habitats (‘polynyas’) in the sea ice during our interval of study. The periods when consumption of krill was reduced are interpreted to correspond to the opening of polynyas over the continental shelf, which became the preferred foraging habitat. Our results challenge hypotheses that the development of extensive, thick, multi-year sea-ice close to the continent was a key driver of positive sea ice-climate feedbacks during glacial stages, and highlight the potential of stomach-oil deposits as a palaeo-environmental archive of Southern Ocean conditions.
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29. The Southern Hemisphere at glacial terminations: Insights from the Dome C ice core
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Roberto Udisti, Hubertus Fischer, Fabrice Lambert, Louise C. Sime, M. de Angelis, Manfred Mudelsee, Valerie Masson-Delmotte, Regine Röthlisberger, Margareta Hansson, Eric W. Wolff, Matthias Bigler, British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Climate Risk Analysis (CRAAM), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Climate and Environmental Physics [Bern] (CEP), Physikalisches Institut [Bern], Universität Bern [Bern]-Universität Bern [Bern], Abteilung Klinische Sozialmedizin, Berufs- und Umweltdermatologie, Universität Heidelberg [Heidelberg], Department of Physical Geography and Quaternary Geology, Stockholm University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry, University of Florence (UNIFI), European Project for Ice Coring in Antarctica (EPICA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-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)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universität Bern [Bern] (UNIBE)-Universität Bern [Bern] (UNIBE), Universität Heidelberg [Heidelberg] = Heidelberg University, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Università degli Studi di Firenze = University of Florence (UniFI)
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food.ingredient ,010504 meteorology & atmospheric sciences ,530 Physics ,Glaciology ,Stratigraphy ,lcsh:Environmental protection ,010502 geochemistry & geophysics ,01 natural sciences ,Atmospheric Sciences ,03 medical and health sciences ,food ,Meteorology and Climatology ,Ice core ,lcsh:Environmental pollution ,Calcium flux ,Sea ice ,lcsh:TD169-171.8 ,Glacial period ,[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology ,lcsh:Environmental sciences ,030304 developmental biology ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,Global and Planetary Change ,geography ,0303 health sciences ,geography.geographical_feature_category ,Sea salt ,Paleontology ,Last Glacial Maximum ,13. Climate action ,Climatology ,Interglacial ,lcsh:TD172-193.5 ,Relative dating ,Geology - Abstract
The many different proxy records from the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core allow for the first time a comparison of nine glacial terminations in great detail. Despite the fact that all terminations cover the transition from a glacial maximum into an interglacial, there are large differences between single terminations. For some terminations, Antarctic temperature increased only moderately, while for others, the amplitude of change at the termination was much larger. For the different terminations, the rate of change in temperature is more similar than the magnitude or duration of change. These temperature changes were accompanied by vast changes in dust and sea salt deposition all over Antarctica. Here we investigate the phasing between a South American dust proxy (non-sea-salt calcium flux, nssCa2+), a sea ice proxy (sea salt sodium flux, ssNa+) and a proxy for Antarctic temperature (deuterium, δD). In particular, we look into whether a similar sequence of events applies to all terminations, despite their different characteristics. All proxies are derived from the EPICA Dome C ice core, resulting in a relative dating uncertainty between the proxies of less than 20 years. At the start of the terminations, the temperature (δD) increase and dust (nssCa2+ flux) decrease start synchronously. The sea ice proxy (ssNa+ flux), however, only changes once the temperature has reached a particular threshold, approximately 5°C below present day temperatures (corresponding to a δD value of −420‰). This reflects to a large extent the limited sensitivity of the sea ice proxy during very cold periods with large sea ice extent. At terminations where this threshold is not reached (TVI, TVIII), ssNa+ flux shows no changes. Above this threshold, the sea ice proxy is closely coupled to the Antarctic temperature, and interglacial levels are reached at the same time for both ssNa+ and δD. On the other hand, once another threshold at approximately 2°C below present day temperature is passed (corresponding to a δD value of −402‰), nssCa2+ flux has reached interglacial levels and does not change any more, despite further warming. This threshold behaviour most likely results from a combination of changes to the threshold friction velocity for dust entrainment and to the distribution of surface wind speeds in the dust source region.
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