On April 28, 2004, the SEC made a significant change in policy in the regulation of large investment banks. On that day, they "decided to allow the five largest US investment banks to substitute advanced mathematical risk models for traditional capital requirements." Al Gore has touted the "success" of such models as a reason to feel confident that computer models can accurately predict long-term climate trends.
But it turns out, as everyone is discovering this week, that computer models are not reality. In fact, computer models are extraordinarily sensitive to their inputs, and small changes in their inputs, or the narrowing of models to ignore certain factors, can make them worse than useless. Computer models are also very easy to force to a preferred conclusion.