[From Bill Powers (2010.05.31,0750 MDT)]
Martin Lewitt 28 May 2010 0534 MDT --
NL: I saw a presentation at the International Conference on Climate Change describing a proposed governor on the climate system to explain the long term stability of the earth's temperature.
BP: I assume this was inspired by James Lovelock's "Gaia" hypothesis, for example his "Daisy World" model. I tried to talk to Lovelock about this but he refused to give control theory any credence. Pretty strange.
Rick Marken's explanation is the same one I tried to give Lovelock. Each organism is acting to control the state of its proximal environment. A plant, for example, controls the state of oxygen and CO2 concentration in its leaves, and thus tends to stabilize those quantities in the immediate vicinity of the surface of the leaves. Due to atmospheric mechanical mixing and molecular diffusion, the result is to tend to stabilize the whole atmosphere, much as a thermostat, in selfishly controlling the temperature of its own sensor, tends to stabilize the temperature of a whole room or house. Of course the degree of stabilization of the external world depends on how closely linked the proximal environment is to the distal one. A thermostat in the attic doesn't have much stabilizing effect on the air temperature in the basement.
Billions or trillions of plants supply most of the oxygen in the atmosphere, so we can assume that the percentage of oxygen worldwide pretty closely follows the average set-point for proximal oxygen concentration near all those plants.
Best,
Bill P.