HR: 0800h
AN: PP51B-1342    [Abstracts]
TI: Climate Sensitivity to Vegetation Distribution in the Early Eocene
AU: * Clifthorne, S J
EM: sclifthorne@es.ucsc.edu
AF: Earth Sciences Deptartment, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064
AU: Shellito, C J
EM: shellito@es.ucsc.edu
AF: Earth Sciences Deptartment, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064
AU: Sloan, L C
EM: lsloan@es.ucsc.edu
AF: Earth Sciences Deptartment, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064
AB: There are large uncertainties associated with the reconstructions of global vegetation distributions for past time periods in Earth history. In order to investigate the influence of the global distribution of vegetation on modeled early Eocene climate, we carried out two experiments with the National Center for Atmospheric Research Community Atmosphere Model (v.2.0.2.). Both experiments used an atmospheric CO2 level of 560 ppm and sea surface temperatures generated in a previous Eocene modeling study (Huber and Sloan, 2001). The experiments differed only in their prescribed vegetation distributions. The first experiment used output from an Eocene study with a dynamic global vegetation model (DGVM) (Shellito and Sloan, in preparation), while the second case used a vegetation scheme based on fossil flora (Sewall et al., 2000). In creating the Sewall et al. (2000) vegetation scheme, no specific atmospheric CO2 level was specified, whereas the DGVM in the study by Shellito and Sloan (in preparation) allowed the initial vegetation to reach equilibrium with a pCO2 level of 560 ppm. Two additional experiments were run with higher atmospheric CO2 concentrations of 1120 ppm; one used output from an Eocene DGVM study with a pCO2 of 1120 ppm (Shellito and Sloan, in preparation), while the second case used the Sewall et al. (2000) vegetation. Comparison of early Eocene climates resulting from each pair of pCO2 experiments allows us to assess the influence of prescribed vegetation upon climate. By evaluating these results at two different levels of atmospheric CO2, we can investigate the combined effects of pCO2 and vegetation upon the resulting early Eocene climate.
DE: 9604 Cenozoic
DE: 3322 Land/atmosphere interactions
DE: 3337 Numerical modeling and data assimilation
DE: 3344 Paleoclimatology
DE: 1610 Atmosphere (0315, 0325)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting