The Intersection

Not surprisingly, in the wake of Tropical Cyclone Larry Australians are beginning to chatter about possible links between global warming and hurricanes. And in at least one venue (The Age), the discussion has taken an interesting turn.

Specifically, it appears that CSIRO, Australia’s national scientific research organization, is expecting that the country will indeed have to deal with stronger cyclones due to global warming in the future. But here’s the catch–based upon its own modeling studies, CSIRO is also expecting to see less storms in total.

CSIRO’s models aren’t the only ones that come up this way. A modeling result out of Japan, which I highlighted a while back, found the following:

A comparison of the experiments suggests that the tropical cyclone frequency in the warm-climate experiment is globally reduced by about 30% (but increased in the North Atlantic) compared to the present day-climate experiment. Furthermore, the number of intense tropical cyclones increases.

This is of course just splendid if you’re living in Florida. For most of the world (according to this study), global warming giveth stronger storms but it also taketh away in terms of the total number of storms. But for the Atlantic, it’s projected to be a double whammy, giveth and giveth.

To be sure, these are all modeling results, the Gospel according to supercomputer, so they must be taken with a grain of salt (as is true of any future projections). They’re a little bit better than mere ungrounded speculation, but also considerably less solid than fact.

Still, the results shouldn’t be ignored. Indeed, based upon my initial reporting, I’ve found that there’s at least a potential logic behind the notion that GW might cause stronger storms but also less frequent ones. If I can get it right, the thinking seems to run like this: Global warming is heating up the oceans, and from a heat transport perspective, one strong hurricane can expel considerably more heat up into the atmosphere than several weaker ones. So in terms of cooling the oceans and transporting heat away from the tropics, more strong storms and fewer total storms makes a kind of sense.

Granted, the truth is that scientists really don’t know enough to say one way or another what’s going to happen with the issue of tropical cyclone frequency. It remains a big mystery. At this point, scientists don’t even understand why it is that there are about 80 tropical cyclones globally per year, as opposed to 8, as opposed to 800.

Once they come to terms with this problem, hopefully they’ll also have a better sense of how global warming will affect the total number of storms in different ocean basins. In the meantime, we in the U.S. can only hope–hope–that that Japanese modeling result is wrong….

P.S.: Posted a comment to Real Climate to seek reaction to this post. Any comments will be noted here.


  1. #1 Mark Paris
    March 22, 2006

    Chris, your post makes me think I see a need for some writing about modeling. Some people, deniers in particular, seem to think that modeling, and climate modeling in particular, should be ignored or discounted because of uncertainties. That ignores the fact that every person on Earth uses modeling to one extent or another. “Modeling” is what we do when we choose our clothes for the day, or go to the grocery store, or choothe rest of our lives. Most of the time the modeling we do is nearly unconscious, and certainly not recognized as modeling. But, in fact, we are predicting what a system will do. Scientific modeling is a quantitative extension of that. Although it has uncertainties, scientific modeling is specifically designed to take those uncertainties into account. Our everyday modeling, the modeling we count on to guide our personal lives, is purely intuitive and subject to far more uncertainties than scientific modeling, and yet we sometimes make profoundly life-changing decisions based on it. Maybe sometime you might think of explaining how modeling works for the lay public.

  2. #2 Chris Mooney
    March 22, 2006

    Well, I did that a bit in the last book–and I expect I shall have to go into considerably more detail in the next one….

  3. #3 Fred Bortz
    March 22, 2006

    An aside, but Tim Flannery will be interviewed on Fresh Air later today about his new book, The Weather Makers.

    I have a short note about it on my blog ( ) with a link to excerpts from my upcoming review of that book and Elizabeth Kolbert’s Field Notes from a Catastrophe.

  4. #4 Shawn Devine
    March 22, 2006

    Although I don’t know if this will answer your question about climate modeling, Mark, RealClimate is a good site for all things Global Warming.

  5. #5 gerald spezio
    March 22, 2006

    Here is an appropriate quote from James Hansen, our man on climate watch; “The most precise knowledge about climate sensitivity comes not from climate models per se, but from empirical information on climate change interpreted with the aid of climate models.”

  6. #6 Mark Paris
    March 22, 2006

    Shawn, my real concern is not my own understanding, but the understanding of the general public about modeling. I use computer simulation and modeling quite a bit in my own work, plus my education was in atmospheric science. My worry is that sites like RealClimate are largly frequented by people with some understanding, plus a gaggle of deniers. What about the general public? Who explains to them that uncertainty is a part not just of climate modeling, but of life in general? I think that’s where people like Chris come in.

  7. #7 Timothy
    March 22, 2006

    You may be interested to know that this pattern [fewer, stronger storms] is also predicted for extra-tropical cyclones. The mechanisms are slightly different as they also involve a decrease in the meridional temperature gradient that doesn’t affect tropical cyclones, but nevertheless…

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