A reader writes… I trust you will critique Ingrid is born; Humberto and Felix–a sign of climate change?. Naturally I’m stupid enough to fall for that sort of a challenge.
On the issue of cat5 records I think he misses the obvious point (stoat passim): cat5 numbers are low, their statistics are unstable, and you can’t tell much from the record. He does say “We’ve now had six Cat 5’s in the past three years, and eight in the past five years. Is this an indication climate change is at work? Well, we did have back-to-back years with two Cat 5’s each (1960 and 1961), so one can still argue that the Cat 5 activity of recent years is a statistical abnormality. In addition, recent work done studying sediment deposits indicates that intense hurricanes have gone through cycles lasting hundreds or even thousands of years long. Periods of high Category 5 activity similar to that observed the past five years could well have occurred in the distant past.” but then ends the piece with “But, the events of 2005 and again this year leave me concerned. Eight Cat 5’s in five years is an awful lot of severe storms in such a short period. Climate change may be indeed be changing Atlantic hurricanes for the worse.” This is all vagueness, but slanted vagueness. You cannot say anything useful *from the numbers alone* but you can spend a long time talking around the numbers in an effort to imply something.
The other thing worth jumping on is this “rapid intensification” thingy. His conclusion is pretty fair: “No scientist has published a paper linking rapid hurricane intensification rates with global warming. While the cases of Humberto and Felix are certainly unique, the year 1969 also had two storms that were very similar in their intensification rates. A quick look I did at historical intensification rates don’t show any noticeable trends, and I think that the rapid intensification rates of Felix, Humberto, and Wilma the past three years are not far enough outside the statistical norms that we need to invoke climate change as an explanation. Still, it does leave one wondering, and climate change could be affecting hurricane intensification rates.” What makes me suspicious is that its a retrospective sign: only now we’ve had an otherwise unexciting hurricane distinguished only by rapid intensification is anyone interested in RI.