Supertyphoon Krosa, Typhoon Alley and Global Warming

Writing recently about the global distribution of hurricanes and typhoons, Houston Chronicle science blogger Eric Berger made this memorable observation: "If you were going to create a new island I would not recommend placing it several hundred miles south of Japan."

And indeed, a look at the tracks of all recorded tropical cyclones bears out Berger's observation nicely: The busiest place of all is a region south of Japan, east of the Philippines, and of course north of the equator. This stretch of relatively open ocean -- call it Typhoon Alley -- is home to the strongest and largest storms of all. Indeed, the record setting storm in both categories, 1979's Supertyphoon Tip, occurred right here.

Typhoon Alley has been busy recently. At the moment, Supertyphoon Krosa is coursing towards Taiwan and possibly mainland China. Krosa closely follows Sepat and Wipha, both of which also reached supertyphoon status (essentially, strong Category 4 strength or higher) along similar tracks.

While Sepat barreled into Taiwan, Wipha originally looked as though it might threaten the Chinese megalopolis of Shanghai. Once again, Krosa could end up near this city of over 20 million, albeit probably in quite a weakened state. The brunt of the punishment is more likely to fall on Taiwan once again, however. Clearly, this storm bears close watching.

Krosa also happens to be our 14th Category 4 or higher storm recorded globally so far this year. Let's put that number in context: As I've written previously, by my count there were there were 19 of these intense storms in 2006, 22 in 2005, and 23 in 2004. It remains to be seen how 2007 will fit into this picture, but I would certainly expect to see several more very intense storms this year. We still have almost three full months to go, after all.

The total annual number of Category 4 and 5 hurricanes is important because it feeds directly into a central argument in the global warming debate -- are we seeing a rise in the total number of the strongest storms? The answer remains very much subject to dispute. Your "Storm Pundit" will be keeping close tabs on strong hurricanes throughout 2007 to determine what the data show.