PP23A-1379:
Constraining the extent and evolution of the Southwest Pacific carbon pool since the last glacial
Tuesday, 16 December 2014
Frank Lamy1, Thomas Ronge1, Ralf Tiedemann2, Franziska Kersten1, Matthias Frische3, Ricardo De Pol-Holz4, Katharina Pahnke5, Brent Alloway6, Lukas Wacker7 and John Richard Southon8, (1)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (2)Alfred-Wegener-Institute, Bremerhaven, Germany, (3)GEOMAR Helmholtz Centre for Ocean Research, Kiel, kiel, Germany, (4)Universidad de Concepcion, Concepcion, Chile, (5)Max Planck Institute for Marine Microbiology, Bremen, Germany, (6)School of Geography, Environment and Earth Sciences, Victoria University, Wellington, New Zealand, (7)ETH Swiss Federal Institute of Technology Zurich, Zurich, Switzerland, (8)Univ California, Irvine, CA, United States
Abstract:
Throughout the transition from the last Glacial to the current Interglacial, rising atmospheric CO2 levels were accompanied by declining atmospheric D14C values. A likely mechanism, influencing both components is the deglacial release of CO2, stored for millennia in the deep Ocean, to the atmosphere. Due to its long residence time within the oceans interior this CO2 rich water mass was considerably depleted in radiocarbon. Although a large number of studies address this topic, the extent, location and pathways of the glacial carbon pool are still subjects of an ongoing debate. As deep water masses are upwelled and new intermediate waters are formed around Antarctica, the Southern Ocean is a potential area for the deglacial release of stored CO2. Here we present radiocarbon and carbonate ion data from a Southwest Pacific transect of sediment cores covering the major water masses in this area, from AAIW down to AABW. During the Glacial, our data locate a significantly 14C depleted pool with apparent ventilation ages of up to ~8000 years at a water depth between 2000 and 4500 m in glacial Pacific Deep Water. Although the redistribution of old carbon from the deep- into the intermediate-water begins at ~22,000 years B.P., the major outgassing pulse from the deep Pacific parallels the rise in atmospheric CO2.
