Saturday, July 21, 2007

Hope Global Warming isn't a Step Function

I don't have a lot I remember from my engineering degree. What I have are some graphs that stick in my mind with metaphorical weight. One of those graphs is a step function.

An example of a step function is an on-off switch. When you flip the lights on the current goes from 0 to full instantly. A graph of someone flipping the lights on and off is a series of boxes like you are stepping up on a step and then down from a step.

Most change is linear or exponential. Sea level rises in increments of inches, or feet over years. If the rate of change is constant its easy to deal with. Not so easy to deal with is exponential change. That's when the rate of change starts increasing and suddenly a population of rabbits goes from 10 rabbits to 100 and then the next time you measure its 1000. Hmm. That's the worry when we talk about temperature and sea levels. How can we keep it linear and stop the move to exponential change.

We worry and fuss and start slowly to action.

But what if it's step! We think of linear change as natural change, but step functions are common in nature. A Tsunami hitting the shore is a step function. Every year in Northern lakes there is a day where the warm water at the bottom flips up to the top when the seasons change. All the fish in the lake wobble around for a week or so trying to figure out what just happened. Its drastic but its natural. Its a great day to go fishing!

There is one more perfectly natural step function that we are all familiar with. Its the step we all have to face one day. Death is a step function. One day we are alive, the next we are dead and nothing is more natural then that.

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