Wednesday, March 3, 2010

Recent Storm Seasons Have Been Mild, Right?

OK. The graph with the 15-year (or 17-year, or 21-year) smooth NH SST and Atlantic storm series looks good, almost too good. I was reminded of that fact recently. But then, you might ask, how do we reconcile this with the fact that Atlantic storm seasons after 2005 have been mild? Should I believe my lying eyes, or... my lying eyes?

Mild compared to what? Anything is mild when you compare it to the Katrina season.

You can search Wikipedia for each year's count, e.g. google "2006 Atlantic Hurricane Season." These are the figures:

2006: 9
2007: 15
2008: 16
2009: 9

The average is 12.25. The average between 1944 and 1990 was 9.8. I'm not saying recent seasons are significantly more busy, but you can't claim they are milder than the 1944-1990 average either.

Clearly, 2007 and 2008 were both considerably more busy than normal. They probably went unnoticed because, again, what could possibly compare to the 2005 season?

Note that I never claimed storms resulting from global warming were going to be the end of us all, or anything of the sort. I haven't even attempted to model it yet. Any projection I made carried a caveat: that the association would have to be linear. But it can't really be linear, can it? I can't say, for example, if the number of storms saturates after a certain temperature is reached.

I never even claimed that there has been a statistically significant rise in the number of storms. It seems reasonable this is the case, but I just haven't done this analysis. What I did is determine whether storms track sea-surface temperatures, and they do.

I will say one thing, though. Do not be surprised if the 2011 or 2012 seasons are quite busy. I'm saying that because 2010 is an El Niño year. It's not the case that busy seasons always follow El Niño years, or that all El Niño years end up producing busy seasons. But based on a quick comparison, it often does happen that way.

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