HR: 0830h
AN: PP21B-1171 [PDF]
TI: Geological Factors and the Evolution of the Greenhouse Effect
AU: * Poulsen, C J
EM: poulsen@umich.edu
AF: Dept. of Geological Sciences
University of Michigan, 425 E. University Ave., Ann Arbor, MI 48103 United States
AU: Huynh, T
EM: tranhu@umich.edu
AF: Dept. of Geological Sciences
University of Michigan, 425 E. University Ave., Ann Arbor, MI 48103 United States
AU: Jacob, R
EM: jacob@mcs.anl.gov
AF: Mathematics and Computer Science Division
Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AB:
For much of Earth history, atmospheric CO$_{2}$ is considered to have been the primary climate driver due to the greenhouse
effect. Yet, there are times in Earth history when this relationship does not hold (e.g., Veizer et al., 2000). The breakdown
of the CO$_{2}$-climate relationship on geological timescales begs the question: what is the linkage between geological
factors and the greenhouse effect?
The influence of geological factors on the greenhouse effect will be tested using a series of paleoclimate experiments
simulated by the Fast Ocean-Atmosphere Model (FOAM), a coupled ocean-atmosphere general circulation model. These experiments
will specifically test the role of continental area and distribution, orography, and atmospheric CO$_{2}$ level on the
climate factors (e.g., cloud fraction and type, specific humidity, incoming and outgoing radiation) that control the
greenhouse effect. Initial model results indicate that the greenhouse effect is sensitive to climatic differences arising
from paleogeographic evolution. The global-average greenhouse effect is approximately 10% greater in a Cretaceous experiment
than in a Triassic experiment with similar atmospheric CO$_{2}$ levels. This increase in greenhouse effect resulting from
differences in paleogeography is greater than that resulting from a fourfold increase in Triassic atmospheric CO$_{2}$
levels. Preliminary model results indicate that factors other than CO$_{2}$ may have been important in the evolution of the
Earth's greenhouse effect.
DE: 0325 Evolution of the atmosphere
DE: 1620 Climate dynamics (3309)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting