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Fact, Fiction, and Friction in the Hurricane Debate

Filed under: — group @ August 18th, 2006

Michael Mann and Gavin Schmidt

Judith Curry and colleagues have an interesting (and possibly provocative) article, “Mixing Politics and Science in Testing the Hypothesis That Greenhouse Warming Is Causing a Global Increase in Hurricane Intensity” in the latest issue of the Bulletin of the American Meteorological Society (BAMS). The article provides a solid review of the recent developments in the science focusing on potential climate change impacts on tropical cyclones. However, the article is more novel in its approach than the typical scientific review article. For instance, it attempts to deal with the issue of how one should test hypotheses that reflect a complex causal chain of individual hypotheses. This is of course relevant to investigations of climate change influences on tropical cyclone activity, where one is attempting to connect a phenomenon (climate change) that is global in spatial scale and multidecadal in timescale, to a phenomena that is intrinsically “mesoscale” (that is, spans at most hundreds of kilometers) in space and lasts only a few days.

More unusually, the article also takes an introspective look at the role of scientists in communicating societally-relevant science to the public, and provides a critical review of how the science dealing with climate change impacts on tropical cyclones and hurricanes has been reported in the media, and how that reporting has occasionally deepened the polarisation on the issue. In doing so, the article revisits some of the “false objectivity” problems we have talked about before (see here and here). They also assess fairly the quality of the arguments that have been made in response to the Emanuel (2005) and Webster et al (2005) papers in the hope of focussing discussion on the more valid points, rather than some of the more fallacious arguments. The article is unapologetic in advancing their particular point of view, and while we generally share it, we imagine that some readers may disagree. We hope, as we suspect the authors do as well, that it will in any case generate a productive discussion.


243 Responses to “Fact, Fiction, and Friction in the Hurricane Debate”

  1. 201

    Thanks Urs for the link to the article on South Indian Ocean hurricanes. The article (pub. 1999 in “Publications de l’Association Internationale de Climatologie, Vol. 12, 1999, 405-413″) ends with an interesting conclusion I would like to summarize here briefely. After in fact stating the rising trend in Hurricane frequency in the Indian ocean Hoarau asks at the end of the article if there is a connection between global warming and the growing number of tropical cyclones in various ocean basins. Based on a study of DeMaria and Kaplan (1994) Hoarau says that the limiting factors of most Hurricanes are in fact a) SSTs and b) the vertical wind structure. He seems to prefer the second possibility and ends literally with the sentence: “This would suggest an influence of global warming on the vertical wind structure”. It is surprising for me that all this fierce fighting here is not really on the trend of the Hurricanes, not even on a potential influence of global warming but just on the question if this influence acts by SSTs or by affecting the vertical wind shear. Anyhow here is the last part of the conclusions:

    Karl Hoarau:
    “Y-a-t-il un lien entre le réchauffement de la Terre donc des océans au cours de la dernière décennie et le plus grand nombre des cyclones tropicaux intenses répertoriés sur la même période dans les trois bassins évoqués dans cette étude? DeMaria et Kaplan (1994) montrent que seulement 20 % des cyclones de l’Atlantique Nord atteignent 80% ou plus de leur intensité maximale potentielle, cas dans lequel l’intensité atteinte par un cyclone est en équilibre avec la température de surface de l’océan en l’absence de contraintes dynamiques dans l’atmosphère. Pour eux, le cisaillement vertical du vent horizontal dans la troposphère est le principal facteur qui empêche la plupart des cyclones de parvenir à l’intensité que leur permettrait la température de l’océan. Par conséquent, la fréquence plus élevée des cyclones intenses durant la dernière décennie pourrait provenir d’un fléchissement du cisaillement vertical du vent horizontal. Cela suggérerait une influence du réchauffement global sur les vents de la troposphère.”

  2. 202
    Sally says:

    Re#194
    Graham, if you can that for Ernesto, what can you do for Ioke?

  3. 203
    Hank Roberts says:

    Babelfish http://babelfish.altavista.com/ translation:

    “[Is there] a bond between the reheating of the Earth thus of the oceans during the last decade and the greatest number of the intense tropical cyclones indexed over the same period in the three basins evoked in this study? DeMaria and Kaplan (1994) show that only 20 % of the cyclones of the North Atlantic reach 80% or more theirs potential maximum intensity, case in which the intensity reached by a cyclone is in balance with the temperature of surface of the ocean in the absence of dynamic stresses in the atmosphere. For them, the vertical shearing of the horizontal wind in troposphere is the principal factor which prevents the majority of the cyclones from arriving at the intensity that the temperature of the ocean would allow them. Consequently, the higher frequency of the intense cyclones during the last decade could come from a decline in the vertical shearing of the horizontal wind. That would suggest an influence of the total reheating on the winds of troposphere.”

  4. 204
    Steve Bloom says:

    Re #200: Of course there’s some connection between the rate of the forcing and the abruptness of the effects, but that applies to natural forcings as well. On the purely natural side of things, it’s well-known that various climate events associated with deglaciations (e.g., the Younger Dryas) have been very abrupt indeed. Also consider the effects of large volcanic eruptions.

    Re #202: Great idea! Haiku seems right.

  5. 205
    L. David Cooke says:

    RE: 204

    Hey Steve;

    You do understand the concept of factitious do you not? I was sharing a poor attempt to say that the observed processes that are toted as being real science by AGW proponents is not true. A simple example is the lifting of several tons with a crane, the kenetic energy expended is almost directly converted to heat and potential energy. My point was a like for like character input/output of an energy exchange is an invalid theory.

    The point is that solar radiant energy input versus ocean radiant energy output is not going to be a direct correlation nor even a correlation with a Granger Test lag. The main issue is an understanding of the physical processes regarding density and the energy transfer along with the conversion of radiant energy to mechanical energy and the currents of the oceans. For instance if the radiant energy input was increasing would there not be an increase in current flows (Other then the THC which is driven by a diferent process.)? Also there is the question of the efficiency of the energy transfere due to the density of the materials. Part of the density discussion is an extension of one from UKweatherworld; however, it relates to the heat exchange by convection between two different density mediums via physical contact (wind/water energy exchange).

    Everything I have seen in my studies indicates that SSTs and wind shear have much less to do with storm potentials then the air pressures due to the upwelling of saturated water vapor and the down welling of relatively cool dryer air. The only effect I have seen from increased SSTs is that the “season” is extended, meaning the possibility of a greater storm count. As to intensity the limiting factor apppears to be the combination of water vapor saturation and temperature difference between surface and the tropopause for prediction of the upwelling potential. In addition, remarkably there is an interesting correlation in the dimension of the upwelling eye that appears to limit the potential maximum pressure drop that will occur in the process.

    I do not know that this is fact only that there exists data that demonstrates this characteristic. The question is whether the prestigious scientific community has seen a similar correltation. Based on the current studies it appears they have not. But, as Graham indicated, the science is still young and with the current focus it maybe possible that this process is outside of supported research. Then again there is also the possibility I am wrong…

    Dave Cooke

  6. 206
    Steve Bloom says:

    Re #205: Yep, Dave, the thing to do when you see something about the science that doesn’t quite make sense to you, especially something kind of basic and important as you have described it, is to assume the scientists involved are *idiots*. :(

    Alternatively, there are some on-line resources available where you could learn about hurricane theory; e.g. Kerry Emanuel’s site.

    [Response: Keep it calm please. - gavin]

  7. 207
    Graham Dungworth says:

    Re#205 My initial concerns were about the path functions for hurricanes and not for the theoretical mechanisms of hurricane formation nor for the predicted relations of hurricane intensity with rising sst’s etc.
    Anyway, Emanuel et al’s interesting theory. We used to use the Carnot efficiencies to predict reservoir turnover for formation oil migration in the subsurface.
    I got down to equation4 on heat dissipation and wind friction transfer. Wind velocities are independent of conditions within the eye of the storm. The Carnot efficiency, based on temperatures but it can be recast as pressure differentials is determined from the eye of the storm, for epsilon=1/3 Tsubscript0 becomes 203Kelvin or -70Celsius, which appears fine. Note equation 4 is cast in intensive properties yet the velocity is dependent upon the extensive properties ie the outer diameter in area measure. To be fair he does say conditions but everyone talks about increasing eye diameters for increasing hurricane intensity and that is an extensive property
    Now the carnot efficiency is not central to the theory. You can still attain the same car velocity by accelerating gently. Hence it can spin up to the same equilibrium wind speed, it just takes longer but with a greater chance that the storm fizzles out. Re-frictional drag alone neglects enthalpic breaking.
    People often ask on these sites. Is a category 6 possible? I’ve been in tropical storms on the equator but never a hurricane. But there are notable differences. I was never hit by hailstones whereas I’ve mixed a few gin and tonics with fresh hail in summer camps at 40-45North.
    I don’t doubt that you are getting the right results. On phase change at constant entropy in an adiabatic process. There are many degrees of freedom for water vapour but few for ice crystals. The latent heat of vaporisation for rain is 570cal/mole. This is released as heat. At the same time ice(hail is formed). The latent heat of fusion for ice is 80cal/mole. There will be a page of derivation but this will end up as breaking energy tending to slow windspeed,as would a rain drop itself, but only if it doesn’t hail out on the ground ie. the hail must form in the hurricane but it phase changes before it rains out as water drops. Any evidence for hail in a hurricane? Re- the astrobleme impact, condensation of alumina, silicates etc will have the same breaking effect. So, the physics should condense to a very simple relationship, if you put the intensive factor
    f*((570-80/490)
    into equation 4
    the fraction becomes dimensionless, where f is Fractional part of ice/water in system, f=1 assuming all water is converted to ice in the ascending wall, it would place a break to maximum wind speed but also slow down the hurricane rate of formation. It’s a wonder that hurricanes are so rare with such high efficiencies.
    It takes about as much energy to melt ice/gram by the temperature differential(-70Celsius to 20Celsius) as it does to defrost it/gram.
    Does anyone measure the temperature of the rain? Does hurricane hail make it to the ground? When Ernesto or others returned to storm category was hail common? Finally,this will have been covered somewhere before in planetesimal formation during the accreting Earth.

  8. 208
    Steve Bloom says:

    Re #204: OK, OK, by popular demand (and with apologies to Blue Oyster Cult):

    Who’s our super storm?
    Oh no, there goes Tokyo –
    go go Ioke!

  9. 209
    Graham Dungworth says:

    Re# 207
    Correction:-
    ((570-80)/570)

  10. 210
    Harold Brooks says:

    Re: 207. Hail isn’t common in tropical storms. The updrafts aren’t particularly strong (~10 m/s), so that large stones are unlikely to be formed. In addition, the environment tends to be warm through the troposphere, so the 0 C height is very high. As a result, any hail that does form would have a long time to melt on its way down.

  11. 211
    L. David Cooke says:

    RE: 207

    Hey Graham;

    Actually, I have been in an eye of a Cat. 2 that dissipated to a TS. As to the temperature of the rain I can tell you that it is clearly warmer then a non-tropical thunderstorm, close to surface ambient air temperature. The drops are generally much finer in the outer bands then the inner band, kind of like a fractionalization by the storm winds. Generally, the temperature characteristic would be an indicator that the state change must have occurred at a failry high altitude. Evidence of this appears in the CloudSat first look images.

    It is true that the falling rain drops can provide much of the energy for the wind speeds. This is clear just looking at an example in a down blast in association with bow front straight line winds. Does the pressure difference drive the wind speeds? To some extent; however, the pressure dfferentals are more likely related to the movement of water vapor and not necessarily wind speeds, though your view is an interesting point of view I had not considered.

    Mr. Arhens, had always indicated that the pressure differentiations were more related to a hydrologic circulation balance between the inner band down drafts and the eyewall edge upwelling. Basically, the water vapor flow was described to me as a form of a Van De Graaff Generator. The saturated adiabatic process seems odd in the Cloudsat images of Tropical Storm activity so far. The altitude difference between the base and the tropopause would seem to indicate a limitation related to the terminal velocity of the rain.

    It is very hard to see how the temperature difference could account for the strength; but, might account for the size. How does your calculation help explain the upwelling that provides the water vapor feeds? Are you indicating that the water vapor upwelling source is not via the eye? Experiencing the edge of the eye I can tell you, the winds do drop prior to the clear sky being visable.

    Looking at the CloudSat data does not provide the heat signatures; but the visable reflectivity signature. It is clear that there is a high reflectivity and IR imaging does indicate very cold temperatures at the cloud peaks; however, the band of very high reflectivity is small and only seems to extend from between 12 to 16km. Below this level it is clear that the reflectivity falls and the likelihood that the heat is high enough for the ice to return to liquid state; note that the standard of reflectivity and water vapor state/temperature has not been established, yet.

    Dave Cooke

  12. 212
    James Lindgren says:

    Although I found the Curry et al. BAMS paper mostly persuasive that there had been a very large increase in category 4 hurricanes since 1970 (with drops or no change in the other categories of hurricanes), I see three problems with the paper.

    Starting at 1970. First, the paper dismisses concerns that the choice of 1970 as a starting point may give a misleading account because of the evidence that there was global cooling from 1940 to 1970. They treat this legitimate concern as a logical fallacy, but they never explain coherently what’s fallacious about potentially choosing start or cut-off dates that are unrepresentative of larger trends or that give misleading measurements of the strength of any overall trend.

    Double Counting 1994 Hurricanes? Second, if the authors actually did what they report having done with their data, then the BAMS paper should never have been published. In two charts showing the main hurricane trends, they report the data in five year periods, except for 1994, which is included in two periods, 1990-94 and the six-year period 1994-99. This may be just a typographical error, but they make this error three times in the paper (in most of the most important charts). And exactly the same error appears in another paper they published in Science in 2005 using related data, so it may well not be a typo. If these are not merely typographical errors, and they did what the article reports that they did (i.e., double counted 1994 hurricanes), then the paper should never have been published.

    False Statements to the Public About Category-5 Hurricanes. Third, although the article ended with a substantial discussion of responsible argumentation over the issue of hurricanes and global warming in the mainstream press, as an apparent model they pointed to their own public commentary:

    In our AAAS press release . . ., given the recent devastation associated with Hurricane Katrina, the main public message that we wanted to communicate was

    The key inference from our study [in Science released along with the press release] of relevance here is that storms like Katrina should not be regarded as a “once-in-a-lifetime” event in the coming decades, but may become more frequent. This suggests that risk assessment is needed for all coastal cities in the southern and southeastern U.S. . . . The southeastern U.S needs to begin planning to match the increased risk of category-5 hurricanes.

    Katrina was a category-5 hurricane at its peak, but it was a category-3 hurricane when it hit the Gulf Coast, and it was only a category-1 hurricane at New Orleans (95 mph), though it was just below the threshold for a category-2 hurricane.

    But the data presented in the BAMS paper show what looks to be a very small and statistically insignificant rise in category-5 hurricanes from 1970 through 2005 (these data include some Pacific as well as some Atlantic hurricanes). The big increase shown in the BAMS paper is almost a tripling of category-4 hurricanes; other classes of hurricanes seem to show significant drops or no significant changes.

    A 2005 Science article co-authored by the same group as the BAMS paper–Webster, Holland, Curry, & Chang, “Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment”–does look at Northern Atlantic hurricanes 1970-2004 separately from Pacific ones, but lumps category-4 and category-5 storms together, showing an increase for the combination, not reporting anything on category-5 hurricanes alone. I went to the data source cited in the 2005 Science paper and this is what I found for 1960-2004 hurricanes (the Science study covered 1970-2004, excluding the first two rows below and the 4 category-5 hurricanes that occurred after the period of their data, in 2005):

    Category 5 Hurricanes in the North Atlantic:
    1960-64 . . 4
    1965-69 . . 2
    1970-74 . . 1
    1975-79 . . 2
    1980-84 . . 1
    1985-89 . . 2
    1990-94 . . 1
    1995-99 . . 1
    2000-04 . . 2

    As you can see, in the data they claimed to have used in their Science article (as I counted the events), there is absolutely no trend in category-5 hurricanes in the period of their study: 1970-2004. Indeed, the 1990s showed insignificantly fewer hurricanes than either the 1970s or 1980s. Thus, all of the increase in the North Atlantic category 4-5 storms reported in the 2005 Science article must be due to an increase category-4, not category-5 storms.

    Neither paper reports any data that would show a statistically significant increase in category-5 storms that would form the scientific basis for their public claim, made along with their release of the 2005 Science article: “The southeastern U.S needs to begin planning to match the increased risk of category-5 hurricanes.”

    What increased risk?

    If they have the data to support that claim, they should make it public. Anyone reading that claim would think that their Science paper showed such a significant increase. But it didn’t. Even after I added the 2005 data on category-5 hurricanes, which they did not use because the season wasn’t over yet, the quick regressions I ran didn’t show any statistically significant increase in category-5 storms.

    Did they just fabricate this claim of “increased risk” of category-5 storms?

    If they don’t have such data – and it appears that they don’t – then it’s irresponsible for a scientist to imply a scientific basis for such a fear-inducing claim released along with a scientific paper. And it’s particularly odd that the authors of the 2006 BAMS paper actually discuss and criticize the mainstream press for poor environmental reporting that gives too much weight to critics of the environmental orthodoxy. The authors tell us that their scrupulousness put themselves at a disadvantage in public debate because they restricted themselves to making claims that were supported by peer-reviewed articles and data. Yet their own peer-reviewed data would seem to me to show that they had no scientific basis for saying that “The southeastern U.S needs to begin planning to match the increased risk of category-5 hurricanes.”

    Bottom line:

    1. The new BAMS article shows persuasive evidence of a huge jump in category-4 hurricanes 1970-2004, but declines or flat trends in the numbers of stronger and weaker hurricanes.

    2. The BAMS article does not deal adequately with whether its choice of a relative cool period (1970) as a starting time influenced the results.

    3. In both their 2005 Science article and their 2006 BAMS article, the authors appear to double count data from 1994, but it may just be the result of repeated typographical errors in both journals.

    4. In the BAMS article, the authors criticize others for irresponsible public statements on global warming and praise their own caution, yet the press release they quote asserts an “increased risk” of category-5 hurricanes threatening the southeastern U.S., but neither their own two articles, nor the data they claim to have used, show any such statistically significant trend.

    5. If the quality of peer review and editing in this field is only as careful as it seems to be on the BAMS paper, then I think it prudent for educated lay people to continue to be skeptical about the research and public assertions of climate experts, especially those who tell you to just trust them or who insist that they are just relying on what their data show. Wouldn’t expert reviewers of the BAMS paper already know that there had been no increase in category-5 hurricanes in the North Atlantic, and thus that the public statements that the authors proudly trumpet were irresponsible? Certainly, this brief foray into the literature leads me to be less confident of the conclusions of climate researchers, no matter how fervently they are asserted.

    James Lindgren
    Professor of Law
    Northwestern University

  13. 213
    Steve Bloom says:

    Re #212: A brief deconstruction of your summary points:

    1. The new BAMS article shows persuasive evidence of a huge jump in category-4 hurricanes 1970-2004, but declines or flat trends in the numbers of stronger and weaker hurricanes.

    Reply: OK.

    2. The BAMS article does not deal adequately with whether its choice of a relative cool period (1970) as a starting time influenced the results.

    Reply: The BAMS article shouldn’t (and couldn’t) have recapitulated the entire contents of it references. Webster et al (2005), which you say you read, addresses the issue thoroughly:

    “We deliberately limited this study to the satellite era because of the known biases before this period (28), which means that a comprehensive analysis of longer-period oscillations and trends has not been attempted. There is evidence of a minimum of intense cyclones occurring in the 1970s (11), which could indicate that our observed trend toward more intense cyclones is a reflection of a long-period oscillation. However, the sustained increase over a period of 30 years in the proportion of category 4 and 5 hurricanes indicates that the related oscillation would have to be on a period substantially longer than that observed in previous studies.”

    3. In both their 2005 Science article and their 2006 BAMS article, the authors appear to double count data from 1994, but it may just be the result of repeated typographical errors in both journals.

    Reply: You could have easily confirmed that it was a typo by comparing the graph with the table immediately following it in Webster et al (2005). The total number of 1990-2004 cat 4-5s in the table matches the number shown in the graph for the three five-year periods from 1990-2004.

    4. In the BAMS article, the authors criticize others for irresponsible public statements on global warming and praise their own caution, yet the press release they quote asserts an “increased risk” of category-5 hurricanes threatening the southeastern U.S., but neither their own two articles, nor the data they claim to have used, show any such statistically significant trend.

    Reply: This amounts to an argument that land use and disaster planners in hurricane-vulnerable areas should plan only for an increase at cat 4s since an increase in cat 5s was not found over the limited period of the study. That would be extremely bad advice. There is no scientific basis for thinking that an increasing storm strength trend would limit itself permanently to cat 4s, and as noted below a good basis for thinking otherwise. As well, bear in mind that extensive areas of the U.S. were vulnerable to cat 4s/5s before this increasing trend was discovered.

    Here is the quoted passage in its full context (from a AAAS interview with Peter Webster):

    “Q. Given that increased intensity, what are the possible ramifications for policy-makers, generally? Would your research have any bearing, at least potentially, on decisions regarding the rebuilding of New Orleans and Gulf Coast?

    “A. The key inference from our study of relevance here is that storms like Katrina should not be regarded as a “once-in-a-lifetime” event in the coming decades, but may become more frequent. This suggests that risk assessment is needed for all coastal cities in the southern and southeastern U.S. for category 5 storms, and for the more northern cities (e.g. New York City) probably for category 3 storms (note the categorical risk for coastal cities at higher latitudes needs to be assessed using typhoon data from the Pacific). The southeastern U.S. needs to begin planning to manage the risk of category 5 hurricanes. There is an additional issue of communicating this increased risk to the public. Past strategies for “weathering the storm” will not work in the face of increased hurricane intensity.”

    So Webster was not implying that Katrina was a cat 5, but rather was using it as an example of the type of disaster that could occur elsewhere. Note also that the vulnerability of New Orleans to strong hurricanes is not that unusual for a populated area. New York City, Chesapeake Bay and Houston are very vulnerable to similar events where the bulk of the damage results from storm surge. As well, Andrew and the somewhat weaker Rita showed that more ordinary stretches of shoreline can host major disasters.

    “Q. More generally, what sort of hurricane activity should the Gulf Coast and the East Coast of the United States expect in the years ahead?

    “A. Besides the overall global trend of increasing hurricane intensity, the key issue of concern raised by our study is that the hurricane intensities in the North Atlantic for the last decade have been lower than elsewhere on the globe. It is likely that the differences among the different ocean basins is associated with natural variability. This implies that at some point within the next decade, there is the risk that the intensity of North Atlantic hurricanes could increase rapidly to the global average (with possibly a concurrent decrease in another ocean basin). The variation of Atlantic hurricanes relative to hurricanes in other basins in the context of known cycles of natural variability needs further investigation.”

    5. If the quality of peer review and editing in this field is only as careful as it seems to be on the BAMS paper, then I think it prudent for educated lay people to continue to be skeptical about the research and public assertions of climate experts, especially those who tell you to just trust them or who insist that they are just relying on what their data show. Wouldn’t expert reviewers of the BAMS paper already know that there had been no increase in category-5 hurricanes in the North Atlantic, and thus that the public statements that the authors proudly trumpet were irresponsible? Certainly, this brief foray into the literature leads me to be less confident of the conclusions of climate researchers, no matter how fervently they are asserted.

    Reply: I think this is where you started.

  14. 214
    Hank Roberts says:

    The descriptions “proudly trumpet” and “fervently … asserted” are rather odd in the context.

  15. 215
    Graham Dungworth says:

    Re#213,214,215
    I read nothing odd or out of context. James’ brief? foray into the scientific literature represents the best critique I’ve ever read within the peer review system! This multidisciplinary field with interdisciplinary interpretations has political and social ramifications.
    James is a “new kid” on the block.
    Like Cicero before him said “if you want any friends in this game, buy a dog”.Cicero was the first lawyer of merit and the last Republican leader of the Roman senate before he lost his head,hand and tongue, a consequence of his big mouth.

    The bottom line is to replot the data according to James’ implications and put them upfront on this forum.

    Ideally, the authors of the Bam report are most suited to do this, as central to the critique is that of “data selectivity” that might affect preconceived opinions.This BAM report primarily addressed hurricane intensity and it’s possible relationship with global warming.
    James’ quote-
    “In the BAMS article, the authors criticize others for irresponsible public statements on global warming and praise their own caution, yet the press release they quote asserts an “increased risk” of category-5 hurricanes threatening the southeastern U.S., but neither their own two articles, nor the data they claim to have used, show any such statistically significant trend.”
    may give cause for some to question the wider role of climate change and not solely global warming, that are induced by anthropogenic emissions, changes in land use, water quality etc for which there is direct empirical data in the form of images, and not in mathematical treatments of theory and simulated models.

    James has provided a very perceptive critique. We should contemplate Cicero’s advice and shoot the messenger(lol).

  16. 216
    Steve Bloom says:

    Re #215: Er, did you read my response? Liking the conclusions James came to is a poor reason for endorsing his analysis. Also, if it’s the best critique you’ve ever read, perhaps you need to do some more reading.

  17. 217

    I really enjoyed Professor Lindgrems critique, a perfect example, shows the pitfalls in translating a science paper to the legislative process quite well. As it should not be, rather an attempt to prop up a point of view contrary to the intent of the text. Implying incompetence or worse a bent interpretation of the facts. The very stuff of a legislative process, imperfect as it is as well, coming up with expected laws (or no regulations at all) from a war of words full of emotions instead of a search for correct dry quite cerebral facts. Is a wonder we got here so far at this advanced stage of civilization, but the science is way ahead of democratic processes, finding comfort in words rhetoric and irony and making decisions from them.

  18. 218
    James Lindgren says:

    Re #213, 212, & 215:

    In #215 Graham wrote about my post (#212):

    “James’ brief? foray into the scientific literature represents the best critique I’ve ever read within the peer review system!”

    Thanks, Graham, for your extravagant praise. You are indeed too kind.

    Graham wrote in part to disagree with Steve Bloom’s attempt in #213 to provide what he calls “A brief deconstruction” of my summary points in #212. Given some of the odder comments here (e.g., #216) that seem to attack me because I am a law professor, perhaps I should have added that I have taken over a dozen courses in statistics and statistical inference over the last few years and am nearing the completion of my Ph.D. in Sociology at the Univ. of Chicago, with a concentration in social statistics. So to the extent that you are trying to criticize my argument based on the field from which I write, you should know that I approach these things, not as a law professor, but rather as a social scientist with fairly heavy training in statistics.

    First, it appears that Steve and I agree on what I view as the main accomplishment of the BAMS paper:

    1. The new BAMS article shows persuasive evidence of a huge jump in category-4 hurricanes 1970-2004, but declines or flat trends in the numbers of stronger and weaker hurricanes.

    Next, Steve takes issue with my argument about the possible implications of the 1970 starting date.

    My second point (in #212):

    2. The BAMS article does not deal adequately with whether its choice of a relative cool period (1970) as a starting time influenced the results.

    Steve’s Reply (in #213): The BAMS article shouldn’t (and couldn’t) have recapitulated the entire contents of it references. Webster et al (2005), which you say you read, addresses the issue thoroughly:

    “We deliberately limited this study to the satellite era because of the known biases before this period (28), which means that a comprehensive analysis of longer-period oscillations and trends has not been attempted. There is evidence of a minimum of intense cyclones occurring in the 1970s (11), which could indicate that our observed trend toward more intense cyclones is a reflection of a long-period oscillation. However, the sustained increase over a period of 30 years in the proportion of category 4 and 5 hurricanes indicates that the related oscillation would have to be on a period substantially longer than that observed in previous studies.”

    My Reply:
    I had read the passage that Steve quotes before I posted, and it seems to confirm my point, since it tends to emphasize what the authors wrote in the BAMS article about a cooling period ending in 1970. I did not accuse the authors of the BAMS paper of bias; I did not say that they should have chosen a different period. I said that “the paper dismisses concerns that the choice of 1970 as a starting point may give a misleading account because of the evidence that there was global cooling from 1940 to 1970,” and that they do “not deal adequately whether [their] choice of a relative cool period (1970) as a starting time influenced the results.”

    The authors admit that 1970 is near a minimum. They argue that the world cooled from 1940 to 1970. So it would seem that Steve has pointed to the precise language to support my prior concern over start or cut-off dates that might be ‘unrepresentative of larger trends or that give misleading measurements of the strength of any overall trend.”

    I don’t know how extensive Steve’s statistical training is, but if it is extensive, then he must recognize the potential problems I raised: using 1970 as a start date may give a misleading picture of the larger trend or it may give a misleading measure of the strength of that trend. These are hardly contentious observations (and do not involve a suggestion that the authors made a mistake in starting at 1970 because of the poor quality of data before 1970). In any event, thanks, Steve, for quoting language from the Science article that so clearly supports my point.

    My third point (in #212):

    3. In both their 2005 Science article and their 2006 BAMS article, the authors appear to double count data from 1994, but it may just be the result of repeated typographical errors in both journals.

    Steve’s Reply (#213): You could have easily confirmed that it was a typo by comparing the graph with the table immediately following it in Webster et al (2005). The total number of 1990-2004 cat 4-5s in the table matches the number shown in the graph for the three five-year periods from 1990-2004.

    My Reply:
    Steve, I wonder whether you are serious in this argument. The authors’ repeated claims that they included 1994 in two different periods (1990-94 and 1994-99) are clearly errors, and there is no way to tell whether they are typos or something more serious from just looking at the two papers.

    First, the graph immediately preceding the table does not have any data labels, so one can’t compare and confirm whether the authors double counted 1994 or instead made 4 typos in two different papers (as you are certain they did). All one can do is eyeball the data in the chart, which is not at all clear whether it matches the data table. Indeed, from my eyeballing of the data, I would have estimated more than 270 cat-4 and cat-5 hurricanes 1990-2004 in the chart you point to, not fewer than 270, as the data table you point to shows.

    Second, even if the chart were drawn in such a way that one could tell whether it exactly matched the data table (which it most definitely isn’t), one still couldn’t know whether they double counted 1994 or instead made 4 typos. If the authors mistakenly counted 1994 hurricanes in two of the three groups of years comprising the 1990-2004 period–and summed their three groups to get the total for 1990-2004–then the chart and the table would match exactly and the data would still be wrong because they double counted 1994. You may have some other basis for knowing that the errors are just typos, but the basis that you give would not persuade any sophisticated, fair-minded reader.

    My fourth point (in #212):

    4. In the BAMS article, the authors criticize others for irresponsible public statements on global warming and praise their own caution, yet the press release they quote asserts an “increased risk” of category-5 hurricanes threatening the southeastern U.S., but neither their own two articles, nor the data they claim to have used, show any such statistically significant trend.

    Steve’s Reply: This amounts to an argument that land use and disaster planners in hurricane-vulnerable areas should plan only for an increase at cat 4s since an increase in cat 5s was not found over the limited period of the study. That would be extremely bad advice. There is no scientific basis for thinking that an increasing storm strength trend would limit itself permanently to cat 4s, and as noted below a good basis for thinking otherwise. As well, bear in mind that extensive areas of the U.S. were vulnerable to cat 4s/5s before this increasing trend was discovered.

    Here is the quoted passage in its full context (from a AAAS interview with Peter Webster):

    “Q. Given that increased intensity, what are the possible ramifications for policy-makers, generally? Would your research have any bearing, at least potentially, on decisions regarding the rebuilding of New Orleans and Gulf Coast?

    “A. The key inference from our study of relevance here is that storms like Katrina should not be regarded as a “once-in-a-lifetime” event in the coming decades, but may become more frequent. This suggests that risk assessment is needed for all coastal cities in the southern and southeastern U.S. for category 5 storms, and for the more northern cities (e.g. New York City) probably for category 3 storms (note the categorical risk for coastal cities at higher latitudes needs to be assessed using typhoon data from the Pacific). The southeastern U.S. needs to begin planning to manage the risk of category 5 hurricanes. There is an additional issue of communicating this increased risk to the public. Past strategies for “weathering the storm” will not work in the face of increased hurricane intensity.”

    So Webster was not implying that Katrina was a cat 5, but rather was using it as an example of the type of disaster that could occur elsewhere. Note also that the vulnerability of New Orleans to strong hurricanes is not that unusual for a populated area. New York City, Chesapeake Bay and Houston are very vulnerable to similar events where the bulk of the damage results from storm surge. As well, Andrew and the somewhat weaker Rita showed that more ordinary stretches of shoreline can host major disasters.

    My Reply:
    Steve, you write: “Here is the quoted passage in its full context.” This is false.

    You claim to show the passage that I quoted “in its full context,” but you don’t include the sentence that I quoted (and criticized), which was taken directly from the 2006 BAMS paper. I quoted ALL of the indented quotation that appeared in the BAMS paper. Here is the exact wording of the BAMS paper that I quoted. (The ellipsis is in the BAMS paper itself; I added the bracketed phrase):

    The key inference from our study [in Science released along with the press release] of relevance here is that storms like Katrina should not be regarded as a “once-in-a-lifetime” event in the coming decades, but may become more frequent. This suggests that risk assessment is needed for all coastal cities in the southern and southeastern U.S. . . . The southeastern U.S needs to begin planning to match the increased risk of category-5 hurricanes.

    I took issue with the last sentence, pointing out that there was no evidence in either the 2005 Science paper or the 2006 BAMS paper of an increased risk of category-5 hurricanes. – Steve, you claim to present this quoted excerpt in its full context, but you do not include the sentence that I challenged.

    You also claim that my comment “amounts to an argument that land use and disaster planners in hurricane-vulnerable areas should plan only for an increase at cat 4s since an increase in cat 5s was not found over the limited period of the study.”

    I said nothing of the kind.

    My goodness, New Orleans was so badly protected that it couldn’t withstand a category-1 hurricane, which is what Katrina was when it hit New Orleans. It may have been fortunate that Katrina had been a cat-5 hurricane at some point, because the New Orleans levees may not have been able to withstand the next cat-2 hurricane, which might not have been scary enough to lead to as extensive an evacuation as happened with Katrina. I wasn’t at all objecting to the advice, which seems eminently sound; I was objecting to the idea that the authors’ data showed a significantly “increased risk of category-5 hurricanes.” It doesn’t.

    Remember that in the 2006 BAMS article, the authors claimed that they were only making arguments that were supported by good scientific data. But in the one indented passage that they quoted they made an argument that was not supported by their data, which presumably is the best available.

    This brings us to your next argument: “There is no scientific basis for thinking that an increasing storm strength trend would limit itself permanently to cat 4s, and as noted below a good basis for thinking otherwise.”

    Steve, your speculation is an entirely plausible one (and it occurred to me before I posted)–but it’s just that, speculation. So far the data reported by the authors of the BAMS and Science studies do not show significant support for your view. If a tripling in cat-4 hurricanes does not lead to any significant increase in cat-5 storms, it’s hard to imagine what kind of a dramatic increase in cat-4 hurricanes could lead to a significant effect on cat-5 storms.

    Steve’s Reply (in #212) continues, quoting a 2005 interview of Webster:

    , what sort of hurricane activity should the Gulf Coast and the East Coast of the United States expect in the years ahead?

    “A. Besides the overall global trend of increasing hurricane intensity, the key issue of concern raised by our study is that the hurricane intensities in the North Atlantic for the last decade have been lower than elsewhere on the globe. It is likely that the differences among the different ocean basins is associated with natural variability. This implies that at some point within the next decade, there is the risk that the intensity of North Atlantic hurricanes could increase rapidly to the global average (with possibly a concurrent decrease in another ocean basin). The variation of Atlantic hurricanes relative to hurricanes in other basins in the context of known cycles of natural variability needs further investigation.”

    My Reply:
    Steve, since Webster’s data shows no statistically significant worldwide increase in cat-5 storms, to the extent that this claim is supported by evidence Webster is arguing that a worldwide increase in cat-4 hurricanes may lead to an increase in cat-4 storms in the North Atlantic. They have no data showing a significant increase in cat-5 storms either worldwide or in the North Atlantic, so this statement that you quote does not bear on my claims at all. It deals with the distribution of cat-4 storms to different basins, not to the risk that cat-4 storms will turn into cat-5 hurricanes.

    Conclusion:
    Steve, it would be hard to imagine a less successful “deconstruction” of my comments, but I think your passion may have gotten the better of you.

    As I said at the beginning, the BAMS article shows very good evidence of a big rise in cat-4 hurricanes in the 1970-2004 period.

    Why do you also have to pretend that the clear errors I point to are not errors?

    This is academics. No one is perfect. Everyone makes mistakes; we can all learn from each other if we have an open mind for both the merits and demerits of new research–on global warming and on other topics.

    James Lindgren
    Northwestern University

  19. 219
    Dan says:

    re: 218. If you truly beleive that there were “clear errors” (a gross assumption), you ought to email the paper’s authors directly or better still, submit your comments to the peer-reviewed BAMS.

  20. 220
    Graham Dungworth says:

    Re# that’s correct Dan. James is perfectly entitled to do that but there’s one rider and a caveat involved.
    Firstly, the senior author of the BAMS paper, Judith, does not regard these commentaries on realclimate as any ordinary blog. Infact she has replied in over 10 posts so far, and there is no reason why she isn’t in the process of responding to James’ critique at this moment.
    I no longer work in academia.That’s the caveat. It is virtually impossible for the public to gain access to the vast majority of scientific journals, subscription prices are prohibitive. Steve Bloom refers to this in his comment 105, that it is rare for a journal to allow free public access, BAMS is a rare exception.

    On a few occasions in the past I have posted a comment, by no means a criticism, to a journal re- a particular paper. The editor will often publish an addendum to the paper in a later edition along with response(s) from the authors. There, the matter ends. The editor requests that further discussions are continued in private.

    The future potential of such commentaries on realclimate.org for one, is immense. For the first time in history an educated public can participate in a multidisciplinary field.This of course requires access to the job. In the UK, free access is allowed subject to the possession of a free library membership card. Town or city dwellers are not denied access to the web. Furthermore, the public if they so wish can participate in using their computers for a variety of boinc projects such as the one I am involved with; the model simulations of climate research eg. as at climateprediction.net.

    This debate and such activities could not be continued on the pages of a scientic journal. If it were then they the editors would have to further request cited references to many of the posts on this blog. It is not at all about providing ammunition for climate change deniers, it is about getting the science right. Any challenges by the deniers will be similarly subject to scrutiny. A vast opportunity now exists, through cyberspace, one not solely for me as a scientist by background, nor for you as some peripheral specialist in a remote discipline, but for everyone.

  21. 221
    James Lindgren says:

    Re: 218-219.

    Dan: Some of the things I note are clear erors. For example, the only dispute about the authors’ including 1994 in two different periods in 2 published papers is whether they are simply typographical errors or whether 1994 was double counted. From the two papers alone, one can’t tell.

    For some of my other claims, such as starting in 1970, I am not claiming error, simply pointing out limitations on the generalizability of the results. I should have been clearer in my sentence in the conclusion of #218 (I was clearer when I posted the same comment at another blog where Steve and I both posted.)

  22. 222
    James Lindgren says:

    Re: 219:

    I have already emailed Judith Curry pointing out the double listing of 1994 and requesting her 1970-2005 data by basin by year by hurricane category.

  23. 223
    Joseph O'Sullivan says:

    The blog that James Lindgren is a contributor to and refers to in #221 is the volokh conspiracy.

    From answers.com http://www.answers.com/topic/the-volokh-conspiracy
    “The Volokh Conspiracy is a weblog which mostly covers United States legal and political issues, generally from a libertarian or conservative perspective.”

    The contributors who control the site are from conservative advocacy groups like Cato and the Mercatus Center who have a hostile view of regulation and the science that supports it.

    #220 (Graham Dungworth) “It is virtually impossible for the public to gain access to the vast majority of scientific journals.”
    Usually you can find many of the articles on sites that don’t charge fees, but usually not until a few weeks after they are published. I don’t subscribe to any journal, but I can usually find the articles online.

  24. 224
    James Lindgren says:

    RE #223 & 217:

    Joseph,

    I am not now, nor have I ever been, a member of Cato or Mercatus, nor have I ever given a paper at these organizations, nor have I ever attended a scholarly conference at these organizations. Indeed, I don’t even know what Mercatus is.

    The implication that the Volokh Conspiracy, which I believe is the most popular group academic blog in any field, might be anti-science is frankly ridiculous. Indeed, while it would be hard to generalize about a range of posters, we might be more fairly accused of being hyper-rational.

    One of the norms of academic debate is that one deals with the merits of evidence and one does not deal in unnecessary ad hominems. Combined with an earlier attack based on my being a law professor (#217), I have to say that some of the posters here — though certainly not most of them (kudos to Steve Bloom for his substantive response)–seem to want to do just as Graham facetiously suggested and shoot the messenger (#215).

    [edited]

    [Response: Keep it focused people. - gavin]

  25. 225
    Judith Curry says:

    Wow, I just spotted all this traffic starting with #212. I am on travel, currently in the UK at ECMWF, have been out of email and internet contact since friday afternoon, and have to prepare two talks this week so I don’t have much time to reply at the moment.

    First, the 1994 thing is a typo. Second, our data is publicly available on our website (and has been availble since the publication of the 2005 paper) at http://www.eas.gatech.edu/research/hurricane_Webster.htm

    A few comments before I have to sign off for now.

    1. Pushing the global tropical cyclone data back to 1970 is apparently already pushing the limits of reliable data, there is no way to go back prior to 1970 for global tropical cyclone data. In the North Atlantic, the period 1970-2004 does introduce a slight positive trend if the AMO does in fact contribute substantially to tropical cyclone activity in the North Atlantic. In terms of going back prior to 1970 to identify a trend associated with global warming, it simply doesn’t make any kind of sense to attempt to construct a linear trend in the time series for the last 100 years given the slight global cooling of the 1950′s and 1960′s. The data in the North Atlantic goes back further, but the data on intensity particularly prior to 1970 is being hotly debated at present.

    2. In terms of our statements in the press release issued in sept 2005, specifically the Q&A from Science, we had NO IDEA that anyone would even pay much attention this, particularly a year later. We never anticipated this paper and subject to become such a big deal. We were as careful as we could be (given our inexperience with press releases and media in general, and specifically were very careful not to overplay the global warming issue). Yes, most of the increase 1970-2004 has been category 4 storms, but of course 2005 set the record for the number of category 5 storms, and records on hurricane intensity and duration are being set in the pacific this season.

    3. People (especially lawyers and frequent bloggers) need to realize that most scientists actively publishing scientific research have “day jobs” that pay our salaries, and that we work well over 40 hours per week. In my case, I administer an academic department with 28 faculty, 150 students, and over 200 people actually employed. I also teach. I have funded research on a variety of other topics besides hurricanes. I do not have all day and night to monitor the blogosphere and a year ago i was almost totally inexperienced with the media. We did not expect this kind of media attention nor did we ask for it. At this point we are doing the best we can to deal with the public requests for information on this topic (including the blogosphere)

    We appreciate the comments and the debate, and I have come to think that blogosphere is a very useful medium for the rapid exchange of ideas. I am amazed that some people have the time to post so much on so many blogs. Unfortunately I do not. I will try to get back to this once my talks for ECMWF are prepared.

  26. 226

    Just out of curiosity, was there ever a category 6 hurricane? Maybe Galveston, TX in 1900? I don’t know one way or the other. Is there a theoretical limit on the size of hurricanes, given the energy available in Earth’s atmosphere?

    -BPL

  27. 227
    savegaia.de says:

    @226
    The Beaufort scale has a hurricane 6 since may 16.

    Today, hurricanes are sometimes described as Beaufort scale 12 through 16, with the standard Saffir-Simpson Hurricane Scale Category 1 equivalent to Beaufort 12, Category 2 to Beaufort 13, and so on.[citation needed] Category 1 tornadoes on the Fujita and TORRO scales also begin at the end of level 12 of the Beaufort scale.

    On the morning of May 15, 2006, mainland China suddenly introduced the extended scale to Force 17 without any prior notice. [1] This extended scale was immediately put into use for Typhoon Chanchu. Hong Kong and Macau keep using Force 12 as the maximum and adopted a set of simpler descriptions for public.

    Beaufort scale wiki

    The Saffir-Simpson Hurricane Scale is a scale classifying most Western Hemisphere tropical cyclones that exceed the levels of “tropical depression” and “tropical storm” and thereby become hurricanes

    Saffir-Simpson Hurricane Scale wiki

  28. 228
  29. 229
    Judith Curry says:

    A few further comments:

    1. The key statement of contention was in our Q&A with Science, which was made in response to the following direct question:
    Given that increased intensity, what are the possible ramifications for policy-makers, generally? Would your research have any bearing, at least potentially, on decisions regarding the rebuilding of New Orleans and Gulf Coast?

    It is not a statement that we made in our Science paper, nor in the news release issued from Georgia Tech. Rather, it was a statement made on a short time fuse at a request from Science, to respond to policy makers and to the catatstrophe in New Orleans. In hindsight, I don’t thing we would change a word that was said. What is said by a scientist in peer reviewed publications in done in a very different context from interacting with the media. Scientists are expected to respond to questions outside of their field that they are ill prepared to deal with, and do not directly follow from their scientific research. This is the so-called value gap between scientists and policy makers that was addressed in the BAMS article.

    2. With regard to category 5 storms, there is no point to trying to identify a trend only in the category 5 storms, owing to the small numbers and the uncertainties in classifying storms with the strongest windspeeds.

    3. It has been very interesting to me to follow the blogs from different segments of people that are interested in this work. In addition to realclimate, there have threads on prometheus and also climateaudit that I have responded to. In addition, I had substantial interaction with the tropical storm community through email (not on public blogs). I could almost write a follow on article from comments from the blogosphere, broadening it to include input from statisticians, lawyers, policy scientists, etc. Some very different perspectives, and I have learned something from many of the posts, but mostly that there are very many perspectives on both the science and policy associated with this issue.

  30. 230
    James Lindgren says:

    Re: 225, 229

    Judith,

    Thanks for responding so quickly, especially over a holiday weekend. I also have a day job and a research agenda of empirical projects, one of which was my main focus this weekend. I was not expecting a quick response from your group, and I emailed you solely because for some reason some commenters seemed to think that, rather than simply posting comments on a website discussing the issues raised by your paper, I should contact you directly. In any event, thanks.

    1. I am happy that you have confirmed the ’1994′ errors I found in your two papers, and I am also happy that they are typographical, rather than substantive.

    2. You justify your choice of 1970 as the starting date for your study. My criticism was not whether the starting date was the best one (it probably was), but rather how choosing a relative minimum as the start date should affect the interpretation and generalizability of your results. I think we have both said our piece on this issue; I doubt that further discussion will resolve things any further.

    3. I was pleased that you acknowledged that, as I had pointed out, the data on cat-5 hurricanes shows no significant trend, an observation that was the main focus of my comments (#212). On this point, you wrote:

    With regard to category 5 storms, there is no point to trying to identify a trend only in the category 5 storms, owing to the small numbers and the uncertainties in classifying storms with the strongest windspeeds.

    Of course, statistical significance is determined not only by sample size, but by the strength of any relationship and the variability in the data. From eyeballing your data, it appears that, if the relationship for cat-5 storms worldwide had been as strong as the powerful relationship that you nicely established for cat-4 storms, then the sample size of cat-5 storms was probably large enough to show statistically significant results. So the fact that there is no significant trend in cat-5 storms is due to the absence of a strong relationship in the data, as much or more than to the relatively small sample sizes.

    As for my criticizing your assertion of an increase in the risk of cat-5 storms, which you now acknowledge that your data do not show, you wrote:

    In terms of our statements in the press release issued in sept 2005, specifically the Q&A from Science, we had NO IDEA that anyone would even pay much attention this, particularly a year later. We never anticipated this paper and subject to become such a big deal. We were as careful as we could be (given our inexperience with press releases and media in general, and specifically were very careful not to overplay the global warming issue). . . .

    The key statement of contention was in our Q&A with Science, which was made in response to the following direct question:

    Given that increased intensity, what are the possible ramifications for policy-makers, generally? Would your research have any bearing, at least potentially, on decisions regarding the rebuilding of New Orleans and Gulf Coast?

    It is not a statement that we made in our Science paper, nor in the news release issued from Georgia Tech. Rather, it was a statement made on a short time fuse at a request from Science, to respond to policy makers and to the catatstrophe [sic] in New Orleans. In hindsight, I don’t thing we would change a word that was said. What is said by a scientist in peer reviewed publications in done in a very different context from interacting with the media. Scientists are expected to respond to questions outside of their field that they are ill prepared to deal with, and do not directly follow from their scientific research. This is the so-called value gap between scientists and policy makers that was addressed in the BAMS article.

    I did not rummage through your group’s responses to the press to unearth something your co-authors said in dealing with the press back in 2005. In your 2006 BAMS article, which I was commenting on, you purported to quote just three sentences from your group’s 2005 dealings with the press. These were the sentences that your new 2006 paper chose to emphasize. These were the three sentences that I quoted, taking issue with the last sentence:

    “The southeastern U.S. needs to begin planning to manage the increased risk of category 5 hurricanes.”

    Since, as you now kindly acknowledge, your data show no increased incidence of cat-5 hurricanes–indeed, you argue that “there is no point to trying to identify a trend only in the category 5 storms”–I objected to your group’s use of the phrase “the increased risk of category 5 hurricanes.”

    My criticism thus seems eminently sound, with one strange, but important caveat.

    In #229, you write that the passage I criticize was said in response to a question posed by Science about precautions for hurricanes and you quote those questions. But the phrase that I objected to–”the increased risk of category 5 hurricanes” –does not appear in the
    interview you referenced
    . Webster referred instead to
    “the risk of category 5 hurricanes.”
    In the interview, Webster later refers to “this increased risk,” but in context he appears to be referring to a range of risks from cat-3 through cat-5 that the public needs to address, so there is nothing objectionable about such a reference.

    Judith, can you point me to any place where Webster or anyone in your group actually uttered or wrote the words that you quote in your 2006 BAMS article?

    Or did someone (mistakenly) rewrite Webster’s answer to add a scientific assertion that is not supported by the data you present (i.e., “the increased risk of category 5 hurricanes”)?

    You write: “In hindsight, I don’t thing [sic] we would change a word that was said.” But if you just pointed us to the right source for the text you quoted, it appears that someone (mistakenly) did “change a word that was said”–and changed it to something unwarranted by the scientific data your group presents.

    Is there any way to correct the online version of the 2006 BAMS paper so that the charts are labeled correctly and so that you don’t make a claim of an “increased risk of category 5 hurricanes” if Webster didn’t actually say that in the passage you purport to quote.

    [Response: James, instead of micro-parsing of Webster's comments, think about the physics. All theory and all observations show that tropical storm/hurricane strength is a relatively smooth distribution. Near the extreme end, sampling and the statistics of small numbers make it much more difficult to find significant trends. However, by increasing the categrories (4+5) or (3+4+5) there is clear evidence (given the limitations in the data records) that the distribution of hurricane strength has shifted towards more intense storms. There is no theoretical support for the idea that potential intensity will only increase in the mid range, rather than over the whole range. If the data therefore support the idea that increasing SST is leading to an increase in potential intensity then the conclusion from that is that Cat 5 hurricanes will also increase - because there is no theoretical model that would not lead to that conclusion. How many more Cat 5 might make landfall is another question because that is a small (non-random) subsampling of all storms and is more uncertain. But Webster's statement is a valid inference based on the underlying model that they are working with.

    At the risk of confusing the discussion, think about an analogy: take a pair of die that I suspect may be loaded towards the number 6. After a number of throws, I note that the numbers of 9's 10's and 11's have increased in a statistically significant way, consistent with 6's being slightly more common than normal. However, I have not had enough double 6's to see a statistically significant trend. Given my results, and the model through which I have interpreted them, it is completely valid to expect an 'increased risk' of a double 6, even though I have not yet seen a trend. For hurricanes the inference is very similar and is based on the theoretical underpinnings of how data is interpreted. Each category is not an independent variable - they are dependent on the underlying distribution, and it is that distribution that Webster et al are trying to investigate. - gavin]

  31. 231
    Judith Curry says:

    Jim,

    I don’t have a lawyer’s interest in the exact nuance of wording nor the time or inclination to track down the history of the wording that you are concerned about. Two further points about this:
    1. I agree with Gavin’s comment to your latest message. We were asked to project what might happen in the future, with continued warming. It would have been absurd to extrapolate our analysis to infer that we would see only a continued increase in Cat 4 storms. Based upon our conceptual model of what was going on, we would expect the intensity to continue to increase, so that we would be seeing more Cat 5 storms in the future.
    2. The main point of that section in the BAMS article is that we did not start out talking about global warming, either in our paper or our initial press releases, but rather were forced into this by the media

    Also one further point regarding 1970, and in hindsight I wished I would have included this in the BAMS article. One of the hoped for advantages of breaking our arguments down into the causal change was that we would not continue to be expected to address the global warming detection/attribution issue. The global surface temperature record for the last 100 years is well characterized and the attribution of the variations (including the cooling ca 1940-1970) is well understood and characterized in a large number of publications and assessment reports. Given this, what is going on with the tropical cyclones? The period since 1970 is the period associated with the largest greenhouse warming signal, which coincides with the data set on tropical cyclones that is available. Consider the following scenarios for what the tropical cyclone data from 1940-1970 might say:

    A. 1940-1970 shows tropical cyclones with lower intensity than in the 1970s
    B. 1940-1970 shows tropical cyclones with higher intensity than in the 1970s but lower than that since the 1990s
    C. 1940-1970 shows tropical cylones with higher intensity than the period since the 1990s.

    Which scenario would best support our global warming arguments? Not A, but B! Our arguments state that average TC intensity follows the average trend in SST. So with 1940-1960 warmer than the 1970s, we would expect more intense storms in 1940-1960 than in the 1970s. If the data showed A, it wouldn’t refute our arguments related to global warming but it would certainly raise a lot of questions. Scenario C would arguably refute our hypothesis. So efforts to identify hurricane intensities that are high in the 1940s-1960s are futile in refuting our hypothesis unless intensities are identified to be greater than those we have seen in the past decade. Finding that there is no linear trend since 1940 would not help in refuting our arguments.

    Judy

  32. 232
    Joseph O'Sullivan says:

    Thanks to all the scientists and James Lindgren for taking the time to comment on RealClimate.

    Some of the friction in the Hurricane and in the larger global warming debate is the result of a clash of different processes of obtaining knowledge and coming to decisions.

    I don’t think that #217 was an attack on Mr. Lindgren because he was a law professor, I think it was about how different the political and legal processes are different from the scientific process. Mr. Lindgren’s parsing the language of Dr. Curry’s comments is something normally seen in legal procedures when analyzing the language of a law or a court decision. It’s not bad or wrong, it’s just not the way science works.

    It’s like trying to combine different games with different rules. It’s good when you tackle someone in football but it isn’t good in baseball, and because hockey is played on ice doesn’t mean basketball should be played on ice!

  33. 233
    Graham Dungworth says:

    Re#230 and 232
    Gavin, I’m not certain whether you mean that James has been overly rigorous in requesting precise meaning or that no more causes of hurricane theory be inferred than are necessary to account for observed data. Do we need such precision? Today in the UK “The Times” under a banner headline “Ten-year deadline on Global Warming” are three misleading quotes. One by an obscure Professor Emeritus extolls the politicians to act now citing a ten year irreversible tipping point and that it will take a natural disaster on the scale of Hurricane Katrina for them to act. He never said it was a category 5 nor did he mention New Orleans but it’s now media folklore, it’s what “the Times” infers for its educated readership despite what we now know from the commentaries in realclimate, where James refers to this misunderstanding.

    You cannot implore James to think on the physics, not because he’s a lawyer or a even scientist. There’s many a scientist, called a botanist, who used to classify bats with birds based on morphology, to the indignation of zoologists and they in their turn to geneticists. You would demand rigour for a mathematical proof. Is it wrong for James to demand precise meaning of what constitutes “increased risk”?
    I’m a scientist with a track record but I’m also an educated layman when it comes to Global Warming or Climate change. Neverthelss, my gut reactions place me firmly in the pro camp. There’s one paper I published in 1974 in the Earth Siences that I like to forget, although it was cited a few times. Two years later a rebuttal was published, quite properly, because some of the empirical data I obtained were discovered to be contamination, introduced by the procedure I used. Yet , despite fallacious evidence,the theory I advanced was later shown to be correct. Nevertheless, I still take solace wrongly, in being right for the wrong reasons.

    Hurricane theory is still incomplete. I read the references in detail; we still don’t have empirical data to support several values of the parameters. We fit theory to the data and not vice versa. That’s why many would have binned much of Einstein’s General Relativity.
    The die analogue is great but it has one great flaw in that supposition. If you threw 3 straight sixes within 30 casts you wouldn’t presume the dice was loaded. No, you’d ask for for more throws. That’s what we all now know in detail from both James’ and Judith’s work and her commendable involvement in this forum. We need more data over many more years, yet we all know we may not have time to act, to reverse deletrious change to the environment.

    Judith has made her current position clear. It is not too late for James to send a comment or reply to Judith et al’s paper. It is too late to change the article. Gone? are the days when journals sent out paper addenda for librarians to glue in dusty journals. The Editor may well be perplexed somewhat for a non scientist to break into a “closed shop” but it’s the best case I’ve read for a precedent. Gone are the days when it cost nothing to publish. In this case I’d pay upfront privately and definately not re-allocate from any other grants.

    There’s many a scientist became a magistrate and many a magistrate who might have preferred to become one. Hopefully, James will continue to critically review further research and not otherwise disappear into obscure sociological pursuits. His unique talent as a lawyer is a “sine qua non” for this field.

    Finally, some of you occupy a rather unique position.
    Global Warming, as an aspect of Climate Change, is not about what will one day become obscure albeit accurate references by individuals with polished prose, in obscure journals. It is not even about the media’s perception of the Kyoto Agreement nor its implementation and informing for the common man’s depth of thought.

    What it is about and what it will become is the ridicule that a Great Nation will experience, through greed and self interest, for having failed to act.

  34. 234

    #232 , I didn’t mean anything else in my #217, understood by O’Sullivan and perhaps most readers. This said, I am infinitely more curious about Curry’s and Webster’s opinion, if any, on current ENSO status, apparently getting warmer daily, on the effects it may have on Pacific Typhoons and Atlantic Hurricanes.

  35. 235
    Judith Curry says:

    Here is the latest ENSO analysis from the Australian Bureau of Meteorology. It looks like we are heading into weak El Nino conditions. El Nino implies low TC activity in the Atlantic, and elevated activity in the Pacific

    IDD20730
    Australian Government Bureau of Meteorology
    Northern Territory
    Darwin RSMC – Australia

    Weekly Tropical Climate Note
    at 1300 CST Tuesday 5 September 2006

    El Nino-Southern Oscillation Update
    The 30-day SOI remained fairly steady this week, and at 02 September was -14. Contributing pressure anomalies were 1.9hPa at Darwin and -0.2 at Tahiti. Positive values of the SOI during the past southern hemisphere summer peaked at +20 in mid-April. Since then the SOI has dropped, and been mostly one standard deviation or more below the long-term mean since June. The official monthly SOI for August was -15, and its 5-month running mean centred on June was -5.

    Since May, sea-level pressure anomalies over northern Australia have been persistently high, while pressure anomalies over the tropical eastern Pacific have been mostly lower than average. Over the last month or so warm sea-surface temperature [SST] and upper-ocean heat content anomalies have increased in the near-equatorial central Pacific, while the SST cool tongue in the near-equatorial far-eastern Pacific has weakened, with warm anomalies now evident there. In the atmosphere, there has been an increase in convective activity in the central Pacific, with a typhoon developing in that region during
    August.

    The recently observed conditions described above are consistent with the developing stage of a weak El Nino event, though have occurred somewhat later in the year than is typical. Interestingly, most ENSO forecast models are not predicting the development of a strong El Nino event, and instead indicate the SST pattern in the Pacific will remain below thresholds typically associated with El Nino events. Given current circumstances though, there is a risk that the trend toward a weak El Nino-like state may continue in the short-term at least, and this will be monitored closely. See the Bureau’s “ENSO Wrap-Up” at http://www.bom.gov.au/climate/enso/ which includes links to a compilation of ENSO model predictions.

  36. 236
    Hank Roberts says:

    Gavin’s inline comment is, I hope, clear enough.
    http://www.realclimate.org/index.php/archives/2006/08/fact-fiction-and-friction/#comment-18696

    Another analogy — forest fire size. In fire conditions, we can always see an increase in midsize fires. Even in the worst fire years we don’t always see one or more huge conflagrations. No fire manager argues that there is no increased risk of huge fires and only a greater risk of midsize fires.

    Viewing the same facts in the light of the law, an argument can be made (“it is arguable”) that nothing in the facts demonstrates such an increased risk. That’s true. The known physics and chemistry are not “in” the facts on the table, and would have to be ‘established’ to the satisfaction of the judge by expert testimony. This is a surprise for scientists who don’t work with lawyers regularly.

    Those who can live with this stretch get to make policy.

  37. 237
    Hank Roberts says:

    > 233: “You cannot implore James to think on the physics …”

    No, seriously, it’s important he be able to do so, because he’s trying to understand the nature of the world, going beyond just the words on the page.

    Why does it matter?

    “Russel Seitz, a physicist in Cambridge, MA, has an interesting essay published in op-ed of WSJ (Nov 11, 2005): “Congressional Math” –
    US Congress Assembled contains two physicists, two chemists, two biologists, one geologist, 234 lawyers and an astronaut.”
    http://sun-bin.blogspot.com/2005/11/lawyers-engineers-and-scientists.html

    That’s why we can implore James to understand the physics — because scientists need to learn how to explain the natural world to people who’ve studied law.

    Google “+physics +lawyers” for many anecdotes about the gap in understanding. Many younger lawyers do have physics backgrounds, since patent law has become a major area — but they aren’t yet moving into political office.

  38. 238
    Hank Roberts says:

    Last thought for a while — is the observed increase in the height of the troposphere a measure of storm strength? I’ve thought that the height a thunderstorm could reach before going flat as an ‘anvil cloud’ was the limiting factor on its convective strength, and that’s been increasing for a while. I’d think storm strength would increase along with it?

    http://www.nersc.gov/news/annual_reports/annrep03/advances/5.1.fingerprints.html

    “… One of the most dramatic applications of this “fingerprinting” technique recently answered the question of why the tropopause has been rising for more than two decades. The tropopause is the boundary between the lowest layer of the atmosphere”the turbulently mixed troposphere”and the more stable stratosphere. The “anvil” often seen at the top of thunderclouds is a visible marker of the tropopause, which lies roughly 10 miles above the Earth’s surface at the equator and 5 miles above the poles.

    “The average height of the tropopause rose about 200 meters between 1979 and 1999. In their first comparison of observed data with computer models, Santer and his colleagues concluded that the increase in tropopause height was driven by the warming of the troposphere by greenhouse gases and the cooling of the stratosphere by ozone depletion1. But to quantify the influences (or “forcings” in climate jargon) even further, they considered three anthropogenic forcings – well-mixed greenhouse gases, sulfate aerosols, and tropospheric and stratospheric ozone – as well as two natural forcings – changes in solar irradiance and volcanic aerosols – all of which are likely to influence tropopause height.”

  39. 239

    #235, Thanks Dr Curry, Now that NOAA has declared a weak ENSO event as well, triggerred at an unusual time….. Unusual, that is it! A good question is why, likely because there is a warming accross the equator, not only at the equatorial Pacific, there is a drought in the Amazon, other equatorial regions may also have temperature or weather anomalies, I have not heard of them though. There is a larger image, which is seldom discussed. Perhaps this is why some hurricane forecasters project the wrong numbers…

  40. 240
    Hank Roberts says:

    Has James Lindgren pursued this somewhere else?

    I’m dismayed he’s not followed up here, and hope he will.

    I thought Gavin’s explanation in particular would help; and hoped my analogy to forest fire conditions/fire risk/fire size was appropriate.

    Science relies on, and takes for granted, information that lawyers don’t ordinarily find relevant in their day to day work. It’s a huge gap in perception.

    Anecdote — I recently edited a draft brief for a law student, which basically consisted of advising a client to continue pumping water out of an aquifer at its full rate, since the state law from the 1930s says that’s the only way a company can keep its right to withdraw water (the ‘defense’ is proof of continuing take). I pointed her to extensive USGS documentation that the aquifer, a sand layer under heavy mud, has been collapsing due to overdrafting by both longterm and new industrial users and local governments. I pointed her to the geology — once a loosely consolidated aquifer is overdrawn the grains collapse together, so no subsequent rainfall can “expand” it again. Capacity overdrafted is lost forever.

    I tried to make the argument that defending the right to withdraw water by activities that — since the 1930s case law was decided — are now known to destroy the storage capacity was “destroying the aquifer in order to preserve the right to use it” and made no sense, and suggest attacking the problem in some other fashion. (The USGS has also been pushing water users to address the problem, there’s no lack of scientific approaches, just a lack of lawyers willing to consider them.)

    That’s the kind of situation I see repeatedly when lawyers base their decisions on precedent and language while reality differs. So, here’s hoping.

  41. 241
    Hank Roberts says:

    Ok, Google’s catching up; Lindgren is publishing the same criticism here:
    http://www.climateaudit.org/?p=803#comment-44138
    and here:
    http://volokh.com/archives/archive_2006_08_27-2006_09_02.shtml#1157158094

    where the audience is more supportive of his critique, seems to me on a quick skim. Still hoping he returns here.

  42. 242
    Hank Roberts says:

    The thread at http://volokh.com/posts/1157158094.shtml was last active with a post from Mr. Lindgren on 9/5, after Dr. Curry posted there referring back to this one.

    No progress yet. Still hoping. Others there also tried to make clear the point that the line drawn between a ’5′ and a ’4′ is arbitrary and the risk of strong storms is based on physics of large weather systems not on the category number assigned.

  43. 243

    William Gray overestimated hurricane forecast has been explained by himself and al.:

    http://typhoon.atmos.colostate.edu/forecasts/2006/sep2006/

    “4.3 Causes of August 2006 Over-Forecast

    We view our overestimate of the 2006 hurricane season as a result of our inability to predict the substantial amounts of tropical Atlantic mid-level dryness and the extensive amount of African dust that enveloped this area in August. Rainfall in the African Sahel has also been lower than expected.

    Another factor leading to a less active hurricane season is the continued development of El Nino-like conditions in the eastern Pacific. This has resulted in a modest suppression of 200 mb upper tropospheric easterly wind anomalies in the tropical Atlantic, thereby increasing vertical wind shear in the western Atlantic. Also, there has likely been an increase in subsidence over the tropical Atlantic due to an eastward shift of the Walker Circulation as waters have continued to warm in the central and eastern Pacific.

    The increase of this year’s August hurricane activity in the eastern Pacific is another indication of suppressed Atlantic conditions. These two tropical cyclone basins have tended to be negatively correlated in recent years. When eastern Pacific activity is enhanced, as it has been this August, Atlantic activity is usually suppressed. ”

    Overestimate is an overstatement, forecast numbers have been changed 3 times. So this AMO cycle of 2005 like hurricane seasons for 10 to 20 more years…. Is out of the window? Or not???

    Gray gives his standard rebuke of Global Warming has having nothing to do with hurricanes, but first he has to really be convincing with the forecast numbers, I am not at all impressed….

    I do unique Northern Hemisphere GT projections as a way to understand if I get a refraction theory correctly. I don’t change the estimate during the season in question, modifying a forecast mid-stream is like changing a bet during a horse race, sticking to my original estimate forces me to get it better next time…

    EL-nino was seen warming since April, I’ve often wrote this year was like 1997, the dust from Africa is quite known, interesting, I wonder if it is linked with a warmer North Africa?


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