Noble gases as proxies of mean ocean temperature: sensitivity studies using a climate model of reduced complexity |
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| Authors: | Stefan P Ritz Thomas F Stocker Jeffrey P Severinghaus |
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| Institution: | 1. Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional, La Paz, B.C.S, Mexico;2. Pemex Exploración y Producción, Poza Rica, Veracruz, Mexico;3. Centro de Investigaciones Biológicas del Noroeste, La Paz, B.C.S, Mexico;1. National Oceanography Centre, 6 Brownlow Street, Liverpool L3 5DA, UK;2. Collecte Localisation Satellites, 8-10 Rue Hermès, Parc Technologique du Canal, 31520 Ramonville Saint-Agne, France;3. TOTAL, DGEP/DEV/TEC, Tour Coupole, Arche Nord Coupole/Regnault, 92078 Paris La Défense cedex, France;1. GeoGenetics, Globe Institute, University of Copenhagen, 1350 Copenhagen K, Denmark;2. Department of Geoscience and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark;3. Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark;4. Natural History Museum of Denmark, University of Copenhagen, 1350 Copenhagen K, Denmark;5. DTU Space – National Space Institute, Technical University of Denmark, Kgs. Lyngby, Denmark;6. Department of Geoscience, Aarhus University, 8000 Aarhus, Denmark;7. UiT The Arctic University of Norway, Department of Geosciences, N-9037 Tromsø, Norway;8. Department of Geography, Durham University, Durham DH1 3LE, UK;9. National Museum of Denmark, 1350 Copenhagen K, Denmark |
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| Abstract: | Past global mean ocean temperature may be reconstructed from measurements of atmospheric noble gas concentrations in ice core bubbles. Assuming conservation of noble gases in the atmosphere-ocean system, the total concentration within the ocean mostly depends on solubility which itself is temperature dependent. Therefore, the colder the ocean, the more gas can be dissolved and the less remains in the atmosphere. Here, the characteristics of this novel paleoclimatic proxy are explored by implementing krypton, xenon, argon, and N2 into a reduced-complexity climate model. The relationship between noble gas concentrations and global mean ocean temperature is investigated and their sensitivities to changes in ocean volume, ocean salinity, sea-level pressure and geothermal heat flux are quantified. We conclude that atmospheric noble gas concentrations are suitable proxies of global mean ocean temperature. Changes in ocean volume need to be considered when reconstructing ocean temperatures from noble gases. Calibration curves are provided to translate ice-core measurements of krypton, xenon, and argon into a global mean ocean temperature change. Simulated noble gas-to-nitrogen ratios for the last glacial maximum are δKratm = ?1.10‰, δXeatm = ?3.25‰, and δAratm = ?0.29‰. The uncertainty of the krypton calibration curve due to uncertainties of the ocean saturation concentrations is estimated to be ±0.3 °C. An additional ±0.3 °C uncertainty must be added for the last deglaciation and up to ±0.4 °C for earlier transitions due to age-scale uncertainties in the sea-level reconstructions. Finally, the fingerprint of idealized Dansgaard-Oeschger events in the atmospheric krypton-to-nitrogen ratio is presented. A δKratm change of up to 0.34‰ is simulated for a 2 kyr Dansgaard-Oeschger event, and a change of up to 0.48‰ is simulated for a 4 kyr event. |
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