Coyote Blog

I am writing a paper on climate models, and an important part of that discussion is on positive feedback (most climate models get large changes in future climate through the liberal use of positive feedback assumptions).  I was looking around the Internet for a nice pithy explanation of positive feedback.  This one on Wikipedia was fine, until I got wacked in the face with the last line (emphasis added)

The end result of a positive feedback is often amplifying
and "explosive." That is, a small perturbation will result in big
changes. This feedback, in turn, will drive the system even further
away from its own original setpoint, thus amplifying the original perturbation signal, and eventually become explosive because the amplification often grows exponentially
( with the first order positive feedback), or even hyperbolically (with
the second order positive feedback). An intuitive example is "the rich
get richer, and the poor get poorer."

Wow, intuitive?  How can a statement that is wrong in at least two major ways be intuitive?  First, the poor generally do not get poorer.  In fact, the poor in the United States are in many ways better off than the richest men of the mid-nineteenth century (particular example linked is for the middle class, but many of the same arguments hold for the poor), and better off than the middle class of many nations.  Second, while it might be arguable that there is a positive feedback loop that helps the rich get richer, no such loop is even possible with the very poorest.  Without going into too much detail, the simplest explanation is that with income you can't go below zero.  What people really mean by this statement is that the poor get poorer relative to the rich, rather than on an absolute scale.  Which of course has little to do with positive feedback.  By the way, the rest of the article is equally bizarre, giving more examples of social phenomena that are only weakly linked to positive feedback (Internet echo chamber effect?) rather than physical processes.  It looks like a physics article written by a politics major.

Here are some alternative non-socialist examples of positive feedback from the physical world that actually have the virtue of being true:  Nuclear fission, some exothermic chemical reactions, and acoustic feedback.  In actuality, since positive feedback reactions are so explosive and unstable, they are very uncommon in nature, which is part of the argument against how climate models are constructed.

If you don't know the connection between climate models and positive feedback, see here.