cc: nainfo.teams@usgcrp.gov, nascenarios@usgcrp.gov date: Fri, 17 Sep 1999 11:26:31 -0700 (PDT) from: Philip Mote subject: Re: MORE ON CC AND ATL. HURRICANES to: jim obrien Jim et al., Greetings from the other corner of the Lower 48. In response to your latest message, there are stronger ways to make your case than by claiming that the difference between 10 and 7 is statistically significant. There is a whole body of literature, of which I'm sure you're aware but other recipients of your messages may not be, on trends in tropical cyclones (TCs) (a more general term than "hurricanes") and on the impacts of climate change on TCs. See, for example, pages 169-170 of the 1995 IPCC report (vol I). The trends in intense Atlantic hurricanes are indeed downward, as your landfalling dataset points out. We know about the link that goes El Nino--> fewer hurricanes, but echoing Peter's previous message, do we know yet that climate change-->more El Ninos? the modeling results so far seem (to me) inconclusive. As for future trends in TC's, there seems to be a tendency for models to suggest decreasing trends in TC's, though this too is inconclusive (IPCC95, p. 334). More recent modeling work (e.g., Royer et al., Climatic Change 38, 307-343, 1998) suggests an increase in TC frequency but no extension of the area in which TC formation occurs. I'm sure there are lots of other recent relevant papers but I haven't read them as this is only a peripheral interest of mine, not my field of expertise. All of this is to lead to the suggestion that, as a general principle, whether we're talking to the media or to each other, we make such statements based on the IPCC consensus wherever possible. AND WITHOUT SHOUTING. (by internet protocol, ALL CAPS means you're shouting---but maybe that's what you intended. Besides, lowercase letters are easier for the brain to process.) Phil ======================================================== Philip Mote, PhD JISAO/SMA Climate Impacts Group Box 354235, Univ. of Wash. Seattle WA 98195 phone (206) 616-5346 fax (206) 616-5775 NEW URL: http://jisao.washington.edu/CIG/ ========================================================