May 19, 2008

Changing your mind [LINK]

I was struck by the lede of a recent AP item:

Global warming isn't to blame for the recent jump in hurricanes in the Atlantic, concludes a study by a prominent federal scientist whose position has shifted on the subject.

Two news hooks compete for your attention in this paragraph.

The first is that a widely posited link between global warming and increased hurricane activity may turn out to be unfounded, or that there may even be an inverse correlation. Either of these possibilities run contrary to the narrative that accompanied hurricane Katrina. (This itself should not be particularly controversial, as the IPCC's hurricane specialists posited at best a weak link between the two in the group's most recent report.)

The second is a bit more interesting. Why is it important to note whether the author of the study, Tom Knutson, has changed his opinion over time? Given the unsettled nature of emerging climate science, you would think researchers would change their minds all the time, and that such shifts would be unremarkable.

This paragraph echoes the idea advanced in the lede:

What makes this study different is Knutson, a meteorologist with the National Oceanic and Atmospheric Administration's fluid dynamics lab in Princeton, N.J.

He has warned about the harmful effects of climate change and has even complained in the past about being censored by the Bush administration on past studies on the dangers of global warming.

You're implicitly being asked to make an ad hominem judgement about Knutson.

Perhaps that judgement is that he is more credible in this matter after having held a seemingly contrary position, then abandoning it. The idea is that it usually takes a good deal of contrary data to get people to reassess their positions, especially those they've publicly espoused. Maybe he's done a better job thinking through both angles. Alternately, someone who complains of having been "censored" by the Bush administration cannot be characterized as its puppet or toady.

On the other hand, the judgement could simply be that Knutson is fickle: willing to change his public pronouncements based on the most insignificant shifts in how he interprets the data. Any particular position he stakes out is thus not to be trusted. That may even extend to what Knutson previously believed.

Regardless, I have to wonder if this piece would have made the national news if the report's author consistently posited the same conclusion. "Scientist who's been saying the same thing for many years says it yet one more time." As a matter of science, that shouldn't have any bearing on the report's findings. But this is journalism.

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