Since there is a hurricane approaching the US coast, it's time to finally write this one.
A few years ago a paper was published in Nature that basically said:
If A, and B, and C, .... then there would be more hurricanes globally.
This is a fairly typical structure for a hypothesis. But it struck me as odd that it was published in Nature. Simple hypotheses like this are usually published in more specialized journals where they can attract the interest of other specialists who can contribute analysis of the proposal and data to confirm or deny the hypothesis. The synchronized PR campaign and publicity explained this anomaly. I've seen this before where a hypothetical is used as the basis for political campaigns.
This particular hypothesis included two initial hypotheticals:
- It hypothesized that hurricane frequency and intensity would increase if the temperature gradient between equator and poles increased. This is not proven. There are theoretical reasons that this might be the case, but there are others that would indicate the contrary.
- It hypothesized that global warming would increase this temperature gradient. Again, there are good theoretical arguments for and against.
After lots of publicity came the big lie, and it's a whopper. It's another example of facts being irrelevant. Examination of global hurricane data shows no significant change in hurricane frequency. At the same time the press were bellowing about the increase in hurricane activity, the actual level was slightly below average. The difference was that Katrina and a few other hurricanes hit the US. That generates lots of publicity.
There is a recent increase in North Atlantic activity, which definitely excites lots of publicity. There are claims that this is evidence for global warming, but the hypothesis was about global affects, not a local Atlantic effect. The North Atlantic variability is a known weather cycle, although the underlying physics remain a mystery. The current higher levels were first predicted in a 1955 report to the US Insurance industry. The only reason it's a surprise to the public is the unwillingness of the public to hear the associated message about the dangers of building in dangerous locations.
But this all has nothing to do with the understanding, reality, or characteristics of global warming. The absence of a global increase in hurricanes does not mean there is no global warming. It might mean that global warming does not increase the temperature gradient, or that increased temperature gradient does not increase hurricane activity.
This could have been a quiet internal working paper. But instead it was turned into a big political campaign, complete with misrepresentation of the paper, the real data, etc.