On the issue of global warming, or “climate change” as it is more recently known, call me a skeptic. I am aware of the data showing an increase in average global temperatures over the past half century. And I believe that activity from humans very likely played a part in that. I’m not a denier. But one thing I have always been uncomfortable with is the certainty with which global warming alarmists announce with ever increasing despair that we are headed towards a global catastrophe. Much of this certainty is based on the use of computer ‘models’ which are supposed to predict drastic increases in global temperatures over the next century.

There’s just one problem. Models are often wrong. I’m not talking about climate models in particular. I’m talking about computational models that are used to predict the activity of complex systems such as the Earth’s climate. You don’t have to have a degree in Computer Engineering from a top engineering institution (although I do) or have worked for one of the NSF-funded supercomputing centers (although I did) to understand that computer models can often be wrong, or at the very least incomplete.

Here’s a quote from a recent article from the Wall Street Journal’s Jeffrey Ball on the latest debate over climate change:

A few years of cooling doesn’t mean that people aren’t heating up the planet over the long term. But the cooling wasn’t predicted by all the computer models that underlie climate science. That has led to one point of agreement: The models are imperfect.

A U.S. Senate report (produced when the Republicans were in control of the Senate) contained the following quote on climate model uncertainty:

Climate modelers from four separate climate modeling centers wrote in the October 2000 edition of Nature that, “Forecasts of climate change are inevitably uncertain.” They go on to explain that, “A basic problem with all such predictions to date has been the difficulty of providing any systematic estimate of uncertainty,” a problem that stems from the fact that “these [climate] models do not necessarily span the full range of known climate system behavior.”

As James Taranto of the Wall Street Journal quipped in a recent column: “Can we all agree that the time for declaring that the time for debate is over is over?”