Cloudy Crystal Balls
Computer models may never be able to predict climate accurately
Climate models may never produce predictions that agree with one another, even with dramatic improvements in their ability to imitate the physics and chemistry of the atmosphere and oceans. That’s the conclusion of a report by James McWilliams, an applied mathematician and earth scientist at the University of California, Los Angeles. The mathematics of complex models guarantees that they will differ from one another, he argues. Therefore, says McWilliams, climate modelers need to change their approach to making predictions.
All climate models predict that the Earth will continue to warm, but when pressed to provide more detailed information, they rarely agree. The best predictions vary by 10 to 20 percent or more. For some phenomena, the variations are even more dramatic. For instance, climate models disagree on whether dry spells will, on average, lengthen or shorten.