HR: 0830h
AN: PP21B-1166    [PDF]
TI: Maximum Entropy Production and the Evolution of the Biotic Carbon Cycle
AU: * Kleidon, A
EM: akleidon@umd.edu
AF: University of Maryland, Department of Geography 2181 Lefrak Hall, College Park, MD 20742 United States
AB: The MEP hypothesis states that diabatic processes with sufficient degrees of freedom maintain states at which the rate of entropy production is maximized. A common example in climatology is the application of MEP to poleward heat transport, which leads to predicted equator-pole temperature gradients that are consistent with observations. Here the MEP hypothesis is applied to biotic activity as a diabatic process which affects the atmospheric concentration of carbon dioxide (pCO2) and therefore the strength of the Earth's greenhouse effect. It is first shown with a conceptual climate model that there should be a minimum planetary albedo for which entropy production associated with absorption of solar radiation would be at a maximum as a consequence of the competing effects of surface temperature on the extent of snow cover and convective cloud cover. When pCO2 is simulated by a simple carbon cycle model, it is then shown that the application of MEP to biotic activity leads to an insensitivity of simulated surface temperature to long-term changes in solar luminosity. These predicted changes are consistent with the general suggested pattern of Earth system evolution (decreased greenhouse strength and roughly constant surface temperature through time) and share similarity with the Gaia hypothesis.
DE: 0315 Biosphere/atmosphere interactions
DE: 0325 Evolution of the atmosphere
DE: 4805 Biogeochemical cycles (1615)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting