HR: 11:50h
AN: B21G-07    [PDF]
TI: Advent of Planktic Calcification and Increased Stability of the Climate System
AU: * Ridgwell, A J
EM: andyr@citrus.ucr.edu
AF: University of California - Riverside, Department of Earth Sciences, University of California - Riverside, Riverside, CA 92521 United States
AU: Kennedy, M J
EM: martink@mail.ucr.edu
AF: University of California - Riverside, Department of Earth Sciences, University of California - Riverside, Riverside, CA 92521 United States
AU: Caldeira, K
EM: kenc@llnl.gov
AF: Lawrence Livermore National Laboratory, Climate and Carbon Cycle Modeling Group, Lawrence Livermore National Laboratory, 7000 East Ave, L-103, Livermore, CA 94550 United States
AB: The evolutionary success of planktic calcifiers stabilized the climate system by introducing a new mechanism that acts to buffer ocean carbonate-ion concentration - saturation-dependent preservation of carbonate in seafloor sediments. In the late Phanerozoic, reduction in carbonate deposition on the continental shelves can be compensated for by the increased preservation in deep sea sediments of biogenic carbonate originating from planktic calcifiers living in the open ocean. The result of this is that ocean carbonate chemistry is strongly buffered and the carbon-climate system relatively stable against perturbation of sea level. However, before the advent of biomineralization by pelagic calcareous plankton and benthic metzoa, carbonate deposition would have been largely restricted to shallow water photic environments. Such a system is susceptible to positive feedback between sea level fall, reduced shallow water carbonate deposition, atmospheric CO$_{2}$ draw-down, and ice-sheet growth, raising the possibility of extreme glaciation. This is consistent with the occurrence of ice ages of near-global extent and multi million-year duration during the Neoproterozoic; climatic events that did not reoccur in the Phanerozoic. We employ a coupled atmosphere-ocean-sediment carbon cycle model to demonstrate the fundamental impact of biomineralization in increased stability of the modern climate system.
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 4825 Geochemistry
SC: Biogeosciences [B]
MN: 2003 Fall Meeting