Well well well. 15 named storms this year after all. The last (um, we think) is in the Caribbean right now, spinning way past the season's official endpoint. Its name is Olga. It started out subtropical, but has since become a fully tropical storm with maximum sustained winds of 50 knots at its apparent peak (although the storm has since weakened). But any way you slice it, it's an anomaly to have a storm like Olga so late in the year. As I put it in my latest "Storm Pundit" item: "It was the most average of hurricane seasons, and the most unpredictable of hurricane seasons." Indeed, whatever else you say about the 2007 Atlantic storm season, it was damn long. It began all the way back on May 9 with Subtropical Storm Andrea. And now it is going well into December. This has, inevitably, prompted murmurs about whether global warming may be lengthening season length. My take:
A number of scientists do indeed expect lengthening of the average tropical cyclone season as a result of global warming. Simply put, the tropical oceans ought to warm up enough to sustain hurricanes earlier in the year, and also ought to remain warm enough to sustain them later into the year. This logic suggests that our traditional June/November Atlantic hurricane season bookends may indeed need to topple - that is, provided that no countervailing changes occur as a result of global warming that have the effect of hemming the hurricane season back in again. But of course, there are a lot of complexities here. For example, you will note that our earliest and latest named storms of 2007, Andrea and Olga, were both subtropical in nature.[Note: Olga later became fully tropical.] And as I mentioned previously, the National Hurricane Center didn't even start naming these types of storms until 2002. So I can already hear the argument from skeptics: The season isn't really getting any longer, it's just that now we're paying more notice to subtropical storms.... Maybe that's right. I, however, remain convinced that global warming is already changing hurricanes in myriad ways - but that due to the complexity of the science and the general unpredictability of weather, it is exceedingly hard to detect the effect definitively at this point. In any event, the 2007 Atlantic hurricane season continues to tantalize. In some sense, I'm going to be glad it's over (whenever it finally ends) just so it will stop thwarting, at every turn, my attempts to put it in a box and categorize it.
You can read my full Daily Green "Storm Pundit" item on Olga here.
