In the July 8 Wall Street Journal, Robert J. Caprara describes his direct experience with the process of computer modeling and how results intersect with the motivations of the modeler. Caprara was a consultant to the EPA, charged with building a detailed computer model of the nation’s fresh water sources, including drinking water intakes and sewage discharges in the lakes and streams. He tuned and tweaked the model, and was happy with his preliminary conclusion: the program he had been asked to study had reached a point of diminishing returns and should be wound down. Bzzzzzzt! Wrong answer.

Confessions of a Computer Modeler (Paywall)

Any model, including those predicting climate doom, can be tweaked to yield a desired result. I should know.

When I presented the results to the EPA official in charge, he said that I should go back and “sharpen my pencil.” I did. I reviewed assumptions, tweaked coefficients and recalibrated data. But when I reran everything the numbers didn’t change much. At our next meeting he told me to run the numbers again.

After three iterations I finally blurted out, “What number are you looking for?” He didn’t miss a beat: He told me that he needed to show $2 billion of benefits to get the program renewed. I finally turned enough knobs to get the answer he wanted, and everyone was happy. …

I realized that my work for the EPA wasn’t that of a scientist, at least in the popular imagination of what a scientist does. It was more like that of a lawyer. My job, as a modeler, was to build the best case for my client’s position. The opposition will build its best case for the counter argument and ultimately the truth should prevail. …

Surely the scientific community wouldn’t succumb to these pressures like us money-grabbing consultants. Aren’t they laboring for knowledge instead of profit? If you believe that, boy do I have a computer model to sell you.

A terrific op-ed; you should read it all if possible. Of course, climate models bear a huge role in climate scientists’ claim to “climate consensus”; problem is, the climate did not get the memo. Further reading here.

In Part II (publication TBD) I’ll describe the process of numerical simulation in terms of how it is used in the oil and gas industry, and its relevance to the climate change debate.

Cross-posted.