HR: 17:45h
AN: PP24A-08 INVITED     [Abstracts]
TI: Paleoceanography and Beyond: Changing Perspectives over more than four Decades.
AU: * Kennett, J P
EM: kennett@geol.ucsb.edu
AF: Department of Geology and Marine Science Institute, University of California, Santa Barbara, CA 93106 United States
AB: The astonishing developments in understanding the earth as a developing system through time has resulted, during the last four decades, from a complex interplay between new technologies, the acceptance in the 1960's of plate tectonics and the adoption of a succession of critical paradigm shifts involving past earth system processes. Technologically, ocean drilling and coring, ice coring, marine geophysics and developing geochemical instrumentation have played key roles. Development of paleoceanography has been central to this understanding because of a necessary global perspective from its beginning. Early acceptance of the idea that changing ocean circulation, due to plate tectonic change, affected heat transfer and hence global climate and biosphere evolution stimulated the field. Development of planktonic foraminiferal biostratigraphy played an early, critical step in the development of paleoceanography because of the need for global stratigraphic correlation. This advancement capitalized on existing taxonomic and biostratigraphic developments of the 1960's prior to the plate tectonic revolution and the development of magnetobiostratigraphy when Cenozoic study was largely a land-based enterprise. The advent of ocean drilling led to remarkable advances in understanding of the earth's global evolution through the adoption of a succession of new paradigms during the 1970's and 1980's. These included recognition of a central role of Antarctica in global Cenozoic oceanic, climatic and biospheric evolution; the dynamic role of changes in thermohaline circulation and the deep sea in response to polar cryospheric development; and the affect of continentally-derived regional oceanic salinity changes on changing thermohaline circulation, the so called conveyor-belt hypothesis of late Quaternary climate change. Other critical paradigm shifts involved acceptence of the critical role of changing atmospheric greenhouse gas composition on climate change over different time scales and the effect of changing oceanic circulation on oceanic productivity and hence global biogeochemical cycles. Paleoceanography began to evolve into Earth System History during the 1990's with the recognition of the over-riding influence of dynamic interaction between different elements of the earth's system (lithosphere, hydrosphere, atmosphere, cryosphere, biosphere, and more recently the anthrosphere). In many respects Earth System History grew out of paleoceanography and represents the modern paradigm for many earth scientists. In spite of massive advances in the field, much remains insufficiently explained in Earth System History. Present and future challenges include a pressing need to solve the question of millennial-scale Quaternary climate behavior including abrupt warmings which in turn are relevant to understanding modern global warming. Existing hypothesis appear to be insufficient, suggesting elements of the environmental system are not yet sufficiently considered. As such, the nature of upper intermediate water change requires attention given its potental importance in ocean heat transfer, changing strength of the oxygen minimum zone and instability of methane hydrates. The paleoceanography of continental margins will likely prove critical in future advances.
DE: 1030 Geochemical cycles (0330)
DE: 1724 Ocean sciences
DE: 3036 Ocean drilling
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005