HR: 16:45h
AN: OS14A-04    [Abstracts]
TI: Ocean acidification in the early Eocene and Anthropocene
AU: * Zeebe, R E
EM: zeebe@hawaii.edu
AF: School of Ocean and Earth Science and Technology, Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, MSB 504, Honolulu, HI 96822, United States
AU: Zachos, J C
EM: jzachos@emerald.uscs.edu
AF: Earth Sciences Department, University of California, Santa Cruz, Santa Cruz, CA 95064, United States
AB: Anthropogenic carbon emissions have roughly doubled over the past 35 years and are now ~ 100 times larger than gross fluxes of natural carbon exchange between long-term carbon reservoirs. As the CO₂ invades the ocean, the seawater pH and the carbonate mineral saturation state drop, a process termed 'ocean acidification'. The current rate of this process is likely unprecedented during millions of years of Earth's recent history. The Paleocene-Eocene Thermal Maximum (PETM, about 55 Ma ago) may constitute an analog for the future because the scale of climate and carbon cycle perturbations are potentially comparable to anthropogenic impacts within the next centuries. At the onset of the PETM, surface temperatures rose globally by 5-9 deg C, the ocean pH decreased, and the ratio of ¹³C/¹²C of the surficial carbon reservoirs dropped by about 3 per mil within a few thousand years. We will describe our recent progress in reconstructing changes in deep-sea carbonate chemistry and modeling of carbon cycle changes during the PETM. Our new results on basin-differences in chemistry and dissolution coupled with stable carbon isotope records provide important constraints for modeling the carbon release during the PETM. In particular, it will allow a quantitative comparison between carbon cycle changes in the early Eocene and the Anthropocene. We will discuss the marine biotic response of calcifying organisms to ocean acidification both during the PETM and in the near future. Our results indicate that potentially detrimental effects on marine biota under business-as-USual emission scenarios may be significantly more severe in the future than during the PETM.
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4806 Carbon cycling (0428)
DE: 4912 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4805)
DE: 4930 Greenhouse gases
DE: 4948 Paleocene/Eocene thermal maximum
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting