Precise timing and characterization of abrupt climate change 8200 years ago from air trapped in polar ice |
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| Institution: | 1. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA;2. Department of Geosciences, Oregon State University, Corvallis, OR 97331-5506, USA;3. Laboratoire de Glaci ologie et Géophysique de l’Environnement, CNRS, Saint-Martin d’Héres, France;1. Dept. of Geography, Lower Mountjoy, Durham University, South Road, Durham, DH1 3LE, UK;2. Environment Dept., University of York, Heslington, York, YO10 5NG, UK;3. Programme for Economic Modelling, Nuffield College, 1 New Road, OX1 1NF, UK;4. School of Geography, University of Oxford, South Parks Road, Oxford, OX1 3QY, UK;1. College of Geography Science, Nanjing Normal University, Nanjing 210097, China;2. Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, USA;3. Institute of Global Environmental Change, Xi''an Jiaotong University, Xi''an, 710049, China;1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA;2. Department of Geology, University at Buffalo, Buffalo, NY 14260, USA;1. INSTAAR, and Dept. of Geological Sciences, Univ. of Colorado, USA;2. Centre for Past Climate Studies, Department of Geoscience and Arctic Research Centre, Aarhus University, Aarhus, Denmark;3. Akvaplan-niva AS, Fram Centre, N-9296 Tromsø, Norway;4. Department of Earth Science, University of Bergen, Bergen, Norway;1. Department of Geology, University of Georgia, Athens, GA 30602, USA;2. Department of Geography, Western Illinois University, 1 University Circle, Macomb, IL 61455, USA;3. Department of Geography, University of Georgia, Athens, GA 30602, USA;4. Gobabeb Research and Training Centre, P.O. Box 953, Walvis Bay, Namibia;5. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA;6. College of Global Environmental Change, Xi''an Jiaotong University, Xi''an, Shaanxi 710049, China;7. Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, USA;1. Department of Geology, University of Georgia, Athens, GA, 30602-2501, USA;2. University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK;3. Ice Dynamics and Paleoclimate, British Antarctic Survey, Cambridge, CB3 0ET, UK;4. Institute of Global Environmental Change, Xi''an Jiaotong University, Xi''an, Shaanxi, 710049, PR China;5. Department of Earth Sciences, University of Minnesota, Minneapolis, MN, 55455, USA;6. Department of Geography, University of Georgia, Athens, GA, 30602-2502, USA;7. Mention Sciences de la Terre et de l’Environnement, Domaine Sciences et Technologie, Université d’Antananarivo, Madagascar |
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| Abstract: | How fast and how much climate can change has significant implications for concerns about future climate changes and their potential impacts on society. An abrupt climate change 8200 years ago (8.2 ka event) provides a test case to understand possible future climatic variability. Here, methane concentration (taken as an indicator for terrestrial hydrology) and nitrogen isotopes (Greenland temperature) in trapped air in a Greenland ice core (GISP2) are employed to scrutinize the evolution of the 8.2 ka event. The synchronous change in methane and nitrogen implies that the 8.2 ka event was a synchronous event (within ±4 years) at a hemispheric scale, as indicated by recent climate model results Legrande, A. N., Schmidt, G. A., Shindell, D. T., Field, C. V., Miller, R. L., Koch, D. M., Faluvegi, G., Hoffmann, G., 2006. Consistent simulations of multiple proxy responses to an abrupt climate change event. Proceedings of the National Academy of Sciences 103, 837–842]. The event began with a large-scale general cooling and drying around ～8175±30 years BP (Before Present, where Present is 1950 AD). Greenland temperature cooled by 3.3±1.1 °C (decadal average) in less than ～20 years, and atmospheric methane concentration decreased by ～80±25 ppb over ～40 years, corresponding to a 15±5% emission reduction. Hemispheric scale cooling and drying, inferred from many paleoclimate proxies, likely contributed to this emission reduction. In central Greenland, the coldest period lasted for ～60 years, interrupted by a milder interval of a few decades, and temperature subsequently warmed in several steps over ～70 years. The total duration of the 8.2 ka event was roughly 150 years. |
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