ABSTRACT
I am lucky enough to live in a beautiful patch of woods in southern Indiana and one of my great pleasures is to watch the wildlife and forest outside my offi ce window. The weather can change quickly here-native Hoosiers say that if you don’t like the weather now, just wait an hour or two. I can also watch the regular cycle of seasons, which vary a bit in timing from year to year. But having lived in the same house for twenty years, I can also see a third kind of change-winters are getting warmer, there is less snow and summer is coming earlier, symptoms of global climate change. Systems theorists have names for these three kinds of change. Weather is relatively random noise, produced by a chaotic atmosphere. Seasons are cyclic fl uctuations around a mean, driven by positive and negative feedback. And global warming is a secular change, a transformation of the underlying forces which drive the whole system.
