HR: 11:50h
AN: PP22A-07    [Abstracts]
TI: Reconstructing Neoproterozoic Paleoclimates Using a Combined Data/Modeling Approach
AU: * Sohl, L
EM: les14@columbia.edu
AF: Center for Climate Systems Research at Columbia University, 2880 Broadway, New York, NY 10025, United States
AU: Chandler, M
EM: mac59@columbia.edu
AF: Center for Climate Systems Research at Columbia University, 2880 Broadway, New York, NY 10025, United States
AB: Climate reconstructions of the Neoproterozoic Era (1,000-542 Ma) face special challenges since many proxies used to constrain younger paleoclimates are not available or applicable in Precambrian time. Given the few available proxies, such deep time climate simulations are best viewed as a means to address more fundamental questions about the nature of climate change, and to address disparities in data interpretation by examining phenomena from a process-related perspective. The Global Climate Model (GCM) simulations presented here were aimed at determining what combination of climate forcings might have permitted the initiation of low- to mid-latitude continental ice sheets during a 'snowball Earth' glacial interval. In addition to natural forcings such as greenhouse gases and solar luminosity, models often require certain input parameters for which no paleoclimate proxies exist. For example, in our experiments the average thickness of the ocean mixed layer is specified. The degrees of freedom inherent in these simulations leave open the possibility that model output might reflect a physically plausible but geologically improbable climatic state, so particular care is needed in validating model results with available data. Analysis of our GCM output suggests that the addition of topographic relief and dynamic ice flow to our simulations would more readily permit the growth and persistence of ice sheets in subtropical continental regions. However, these simulations also suggest that `hard' snowball Earth solutions are only likely for much earlier intervals in Earth history.
DE: 0429 Climate dynamics (1620)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 4928 Global climate models (1626, 3337)
DE: 9622 Proterozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting