All this fuss about the “F-word” should not distract from the fact that the mainstream media has problems reporting a science story even if we do pitch it right. Take, for example, Bryden et al.‘s 2005 Nature paper, which reported a 30% slowdown in the strength of the thermohaline circulation (THC), also known as the meridional overturning circulation (MOC), measured across the Atlantic basin at 25ºN. In the wake of this current’s starring role in the ever-so-slightly unrealistic The Day After Tomorrow, this result got widely and breathlessly covered in the press. Even at the time, though, it was clear that this result was preliminary at best. As I commented at the time (in one of my earliest blog posts):

Because the current strengths are being estimated by an indirect method, the potential errors are quite large; in fact, the authors estimate that the error is about the same size as the apparent decrease in [THC] flow. They also argue that because the observed reduction is associated with a particular component of the flow, rather than distributed at all levels, the effect is real, which is a fair point but not a conclusive one. The other problem is that there is virtually no data on the natural variability of the thermohaline circulation, so it is also possible that the most recent survey is just detecting this rather than a sustained reduction.

Some of these caveats did make it into the better write-ups, such as the BBC one linked to above, but most of them treated the reported slowdown as a pretty solid result. End of story. Except that, of course, it wasn’t.

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