My first job out of undergrad consisted almost exclusively of using finite element analysis to model how heat, current, and stress work their way through simple shapes, and what the effects might be, given the material properties. Day in and day out I was building models and running simulations, then trying to figure out if what they told me was anywhere near the truth. Sometimes the excitement of having a model run successfully made it very hard to admit that the results were unlikely.
So when I consider what complexity might be involved in modeling the climate of the earth and predicting to any certainty its future, I am overwhelmed with questions. This document gives a mechanical engineer, and I assume a lot of other laymen, a fighting chance at understanding the scientists' predictions.
We are given an example of a simple model. It includes: ice, water, clouds, and land; evaporation, runoff, heat exchanges, and of course, solar insolation. I wonder what the boundary conditions are, what the predictive equations are, how many versions of the eventual plots were produced and how the "true" ones were selected.
Regardless of which of the models presented actually come to fruition, several possible effects make my skin crawl. We have all seen the predictions that average temperatures will rise somewhere between 1 and 6 degrees F in the next 100 years. The peaks and valleys of that average are my current preoccupation. One map shows the July heat index for most of the U.S. increasing by more than 25 degrees F. Remember that mostly 100 degree summer in 2006? But then there is the matter of summer soil moisture, which considers Austin may become a veritable swamp. It looks like a lot of the quantities and types of trees will change, mostly increasing, but Florida will lose those beautiful pine forests, and the Rocky Mountains will sacrifice its glorious Alpine meadows.