Climate Models and Glitches

Climate is pretty complicated. Unsurprisingly, the computer programs that model them are complex, too. Some of the models have many man-years of development effort that have gone into their creation, and many, many lines of source code.

Of course, any model will imperfectly map to what is being modeled. Video games model a three dimensional world, and even something as simple and straight forward as walls can be tricky:



With a video game, it's easy to see the glitch - where the model does not actually model the subject. With climate models, we don't have the luxury of seeing the obvious - people walking through walls. The glitches are more subtle, meaning harder to find.

But glitches are there, because all software has bugs. This is why it's important that climate scientists make their source code available for other people to examine for bugs. It's also why we need to take the model's output with a grain of salt. Otherwise, you see things like this:

Global warming appears to have stalled. Climatologists are puzzled as to why average global temperatures have stopped rising over the last 10 years. Some attribute the trend to a lack of sunspots, while others explain it through ocean currents.

Ironically, climate change appears to have stalled in the run-up to the upcoming world summit in the Danish capital, where thousands of politicians, bureaucrats, scientists, business leaders and environmental activists plan to negotiate a reduction in greenhouse gas emissions. Billions of euros are at stake in the negotiations.

...

Even though the temperature standstill probably has no effect on the long-term warming trend, it does raise doubts about the predictive value of climate models, and it is also a political issue. For months, climate change skeptics have been gloating over the findings on their Internet forums. This has prompted many a climatologist to treat the temperature data in public with a sense of shame, thereby damaging their own credibility.

Just because we can't see the temperature walking through walls doesn't mean that it doesn't.

Hat tip: Bob S.