Climatic homeostasis

Or, The Thermostat Hypothesis, a guest post by Willis Eschenbach at Watts Up With That.

Organisms employ homeostasis to regulate temperature, chemistry, everything else; IF Gaia is [like] an organism, THEN Gaia is a homeostatic system.

The idea of "Snowball Earth" is an example of what a non-homeostatic system would look like. Although recovery was possible even from the snowball glaciation, if indeed that ever occurred, else we would not be here now. But since the transition from reducing to oxidizing atmosphere, resulting from the evolution of photosynthesis (the real "green revolution"), the homeostasis we know and love today has provided the feedback buffers to keep another snowball from forming, or alternatively keep a runaway greenhouse from boiling the oceans.*

That chart is from Snowball Earth dot org. After we get to "life as we know it" and an atmosphere with free oxygen, the homeostasis sets in, and while we still can have Ice Ages, the best result of which are moderately amusing cartoons, we no longer get out-of-control climate feedbacks. We have a pretty good interglacial going here. What would it take to start another glaciation? Maybe some geoengineering, which need not even be internationally agreed on to have an effect. What the real precautionary principle says is "Don't mess with things you don't understand."

* Boiling the oceans: unlikely. Ian Schumacher has calculations showing that "The earth is operating very close to its maximum possible temperature."