Am I amiss in guessing that Lorenz showed that climate dynamics are non-equilibrium processes? Ian
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No you're not. I was just speculating on how methane can set up a feedback system. After some perturbation climate arrives at some new quasi-stable but different state or at least long periods of regularity that I mistakenly called equilibrium. In any event, I don't think chaotic system models conflict with this idea of arriving at apparently stable nodes, rather it models how that can occur.
Really Ian. Far be it from me to try to dispute or misinterpret the dogma of chaos. I offer apologies in profusion.
In any event here is something I found which sounds like it disputes the Alvarez hypothesis for mass extinction:
``...Trace fossil evidence indicates, therefore, that the entire KT clastic sequence must have been deposited over a long period of time. If the spherules in Unit I are material derived from an extraterrestrial impact, that impact must have predated the extinction of Cretaceous plankton by a significant time interval, which is represented by the periods of deposition of Units II and III. The ichnological information indicates episodic deposition of Units II and III over an extended period of time. Thus, the event that produced the calcite spherules in Unit I is not directly related to the Cretaceous plankton extinctions at the KT boundary, which occur at the top of Unit III...''
(http://www.ngdc.noaa.gov/mgg/sepm/palaios/9812/ekdale.html)
I have to admit a prejudice against the meteorite explanation. I don't have any rational reason and obviously no proof. It just bothers my sense of how things go on. And Alvarez was a nuclear physicists who worked on the Manhattan project (I think) and so naturally he might think in terms of catastrophic events.
Extra-terrestrial catastrophic events are argued for in a sense because of a lack of any other explanation. This idea that geologically produced releases of trapped methane gives a foundational process to link up to the apparent periodicity of mass extinctions. And that sounds a whole lot more appealing to me than meteorites. But then I live in earthquake country and go to the mountains so some form of geology appeals to me.
I have some other speculative agendas in mind also. I think that the largest driver of evolution is geology and climate and that regularities/irregularities in both the environmental and biological systems interact in long term, large scales ways that we are just beginning to see. It seems to me there is a kind of rough concordance between geological time and major evolutionary times. For this idea to have any meaning, however, requires some form of regularity of change, and the some what regular periodicity in mass extinctions might give a glimpse into that temporal concordance. So the idea that meteorites periodically come along just in time to mark out these periodic extinctions is just too much coincidence to shallow. A geologically based process, particularly if it can be tagged to something like plate tectonics is really a lot more friendly to this periodicity of extinction.
Anyway here are some other out to lunch thoughts. Have you ever tried to stare at a shadow and concentrate enough to see it move? It is just beyond my boundary of perception. I can't actually say that I have seen this motion. Why can't you see something that slow? This is a kind of silly curiosity, except it got me to thinking about time scales of change. For example is there any relation between the rates of change in plate tectonics, or geological time, and various physical evolutionary rates in other planets, stars or relative stellar motions?
In other words are there such things as natural temporal units of physical evolution? Do these have any relation to biological rates of evolution?
Chuck Grimes