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Fact, Fiction, and Friction in the Hurricane Debate

Filed under: — group @ 18 August 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. 101
    Sally says:

    Re #98.

    Have you checked out the Pacific storms? Did you notice what Judith Curry said about them earlier? Perhaps you should look at the global picture.

  2. 102
    Steve Bloom says:

    Re #96: Ah, so it’s not just a conspiracy of environmentalists, it’s a conspiracy of *hippy* environmentalists. Thanks for the clarification. :)

  3. 103
    Steve Sadlov says:

    RE: #102 – No conspiracy, just simple demographics. I know about this. I was doing my undergrad at a place of great “revolutionary” reknown a mere 9 years after a nationally newsworthy “uprising.” Those who led it were still largely in the area. I was a teenage / young adult radical, the whole shebang. I know a lot about those who “mentored” me at the time. Hey, at least I’m still a good steward and crunchy con at the personal level. I am very eco-correct ;)

    But I will not hold back on criticism where I think it is warranted.

  4. 104
    Steve Sadlov says:

    RE: #101 – A fairly rough year in the W Pacific for typhoons, whoop-tee-do. Look at the warm pool out there, owing to La Nina. East Pacific has had a non notable year to date. Confession – I am a tropical cyclone geek … :)

  5. 105
    Steve Bloom says:

    Just to note that BAMS is a very rare journal in that the public can read it without charge here. Also, the very informative AMS seminars Judy mentioned can be seen here (with archives link on the left bar). Maybe these could both go in the RC links?

    Also, the Webster et al (2005) paper was not linked in the post, but can be viewed here, and the Hoyos et al (2006) follow-up paper is here. Thank you, Peter, for making these available.

  6. 106
    pat neuman says:

    re 99. The meteorologists at local TV news stations are continuing to convey a message of skepticism on climate change and global warming to the local TV watching public in Minnesota.

    Although the meteorologists are not as direct in their message of skepticism on climate change as they were a year or two ago, their message continues to be skepticism on global warming happening or being a problem.

    Occasionally the meteorologists broadcast false and misleading information to the public. For example, in the late morning TV weather broadcast today, the meteorologist said that so far this month August temperatures have been normal, or normal. However, the average daily mean temperature data at Minneapolis shows that from the first of the month up to this morning, only 3 of the days in August have been below normal. The first six days of August were well above the 1971-2000 normals (and the average 30 year normals used from the NWS are increasing).

  7. 107
    Marcus says:

    Re: #98: Mr Weffer, there is no way that this season can differentiate between the NWS contention of no global warming/hurricane link and the Emanuel et al. contention, since _both_ groups would have argued that this should be a high hurricane year. NWS because of their attachment to the AMO cycle, and Emmanuel because of the continued warming of the globe.

    Of course, to properly apply Emanuel you actually want to take the average SSTs in the south Atlantic and compare them to the # of hurricanes, because I believe that Emanuel believes that the global warming -> hurricane link is due to the global warming -> SST -> hurricane link.

    This still doesn’t help differentiate, because the AMO folk probably believe in an AMO -> SST -> hurricane link. Which means we have to wait until either:

    1) Both groups are totally disproved by a delinking of SST -> hurricanes, or
    2) in a decade or two, average SSTs either continue to rise (global warming) or start falling (AMO).
    3) Better historical statistical data helps differentiate between the two arguments.

    in any case, one year does not a trend make.

  8. 108
    pat neuman says:

    re 106 – I meant my comment in 106 to read: … For example, in the late morning TV weather broadcast today, the meteorologist said that so far this month August temperatures have been have been below normal, or normal. …

    The voice emphasis by the meteorologist was on the below normal for August – which was false or misleading for the TV viewer.

  9. 109
    Steve Sadlov says:

    RE: #108 – Jet stream “wavyness” can be thought to indicate climatic season. The jet tends to get more “wavy” (e.g. steeper and more waves) in fall. In many ways, the “heat wave” during July had characteristics of an “Indian Summer” warm spell, such as the classic “multi barrel” High. But of course, with a July sun angle, it ended up being a major nasty heat event. Subsequently, a typical Fall pattern seems like it might be setting in, in terms of the jet. For example, the West coast, owing to a seemingly persistent deep digger just off shore (and I might add, not unlike some of our springtime persistent Siberia Express set ups I wrote about!), is experiencing the sort of “hint of the approaching rainy season” pattern that we normally see well into September (or even October further south) now. The jet, steep and wavy, manages to loop again all the way over to be coming south into Minnesota / the Upper Great Lakes. Whereas, it was in the 90s in the Dakotas and Minnesota in July, you’re now in the 70s to low 80s. The only 90s band at that latitude is a smidgeon of SW Montana and part of Idaho (but not for long).

  10. 110

    94: The data for all the basins are available at the Unisys weather page.

  11. 111

    I am not sure that there are many folks going around saying that SSTs do not influence tropical cyclone intensity. Surely there is contention about what caused the elevated SSTs (man vs. nature), but that is a separate issue from simply SSTs and tropical cyclone intensity. But, there does seem to me, at least, to be a significant number of folks who are going around downplaying the impact of anything other that SSTs (and enhanced greenhouse effect-raised SSTs, at that).

    Let’s look at the observations from the Atlantic Basin. In our GRL paper (Michaels et al., 2006), we examined the period 1982-2005. Arguably a time of decent intensity records. We found that in order for a tropical cyclone to become a major (category 3, 4, or 5) hurricane, it had to experience a SST of at least 28.25ºC (but beyond that it didn’t matter much). During the 13 hurricane seasons from 1982 to 1994, 71 (or about 5.5 per year) Atlantic Basin tropical cyclones passed over 28.25ºC SST and 16 (or 22.5%) of them, became major hurricanes. During the 11-yr period 1995-2005, 124 (about 11.25 per year) passed over 28.25ºC SST and 42 (or 33.9%) became major hurricanes.

    There are several interesting things going on here. About twice as many tropical cyclones per year in the latter period encountered the critical SST as in the earlier period. This is strong evidence that the SSTs were higher in the 1995-2005 period than they were in the 1982-1994 period (another explanation could be that the storms were tracking over a different portion of the ocean and/or occurred in a different portion of the hurricane seasonâ??but probably this is not a large effect…admittedly though, I haven’t checked this). All else being equal (environmental conditions associated with the higher than critical SST were the same in the latter period as in the earlier period), we would have expected 22.5% of the 124 storms between 1995-2005 (or 28 storms) to have become major hurricanes. This is the number based on SST expectations alone (based upon 1982-1994 conditions). In actuality, there were 42 major hurricanes – 14 more than SST expectations. To me, at least, this argues that changes in other environmental conditions conducive to major hurricane formation must have also occurred. Simplistically, one could argue that SST increases were responsible for about half the increase while other environmental variables were responsible for the other half.

    And, as Hoyos et al. shows there is ample evidence that other changes were happening in the Atlantic during the past several decades that were making things more favorable for hurricane intensification – most notably, Hoyos et al. found a statistically significant decrease in vertical wind shear and a big decline (around 1995) in the moist static stability.

    Clearly, things in addition to SST are controlling the tropical cyclone intensification processes in the Atlantic Basin. The degree to which these other processes are trending in directions theorized under enhancing greenhouse effect conditions is unclear (and no one seems to want to talk about these trends). How much of the observed rise in Atlantic SST during the past 20-30 years is due to enhanced greenhouse conditions is also not agreed upon. But, we all should agree, that risings SSTs do make for conditions more favorable for the development of major hurricanes.

  12. 112
    Bryan Sralla says:

    Tropical cyclone frequency and intensity are both extemely poor climate change metrics. Most of us who have endeavored to read the body of technical work should be able to arrive at some agreement on this point.

    Why would any student of the climate system then want to use a measuring stick where we cannot *clearly* read its numbers (tropical cyclones)? The climate science community has agreed on several clear, solid metrics. For good reasons, tropical cyclone frequency and intensity are not at the top of the list.

    Schmidt, in his explanation of possible changes in the ocean heat content anomoly (a completely vetted and agreed upon metric in the literature) says this:

    “This in turn can have had a number of possible causes: ‘natural’ tropical variability – for instance, the winter (DJF) tropical Pacific cooled over these two years, possibly as part of larger-scale ENSO variability. Alternatively, it may be due to a change in the forcings.”

    If a noted climate scientist explains multi-year changes in ocean heat storage in terms of “tropical variablity” or “weather”, I would suspect that any particularly intense tropical cyclone(or season, or multiple seasons) would surely also fall into this category of “tropical variability”. Schmidt has rightly pointed out on annual and multi-annual timescales, tropical weather is highly variable, and this variablity has a long list of potential causes.

    As professional earth scientists, why cannot we agree to move beyond this discussion, and leave the sensational to the media.

  13. 113
    ike solem says:

    Part I
    Re#62 and #61;
    Those issues relate back to the AMO’s quite questionable role in Atlantic hurricane intensity/frequency and Landsea et al’s oblique attack on the more recent hurricane intensity data in Science which Chuck Booth links to. I think there are a great many questions to be answered regarding the AMO-hurricane link, and the media emphasis on the AMO is somewhat suspicious because of the previous attempt to link Arctic sea-ice decline to an Arctic oscillation.

    (here is a selection of news reports on the Arctic Oscillation issue since 1999):
    http://www.sciencedaily.com/releases/2003/02/030225071423.htm
    http://www.sciencedaily.com/releases/2001/07/010709074127.htm
    http://news.bbc.co.uk/1/hi/sci/tech/523065.stm
    http://www.sciencedaily.com/releases/1999/12/991220082147.htm

    So how does the Arctic Oscillation relate to the North Atlantic Oscillation? Are they actually the same phenomenon? (see the links). While these oscillations may be quite real, the notion that they are responsible for the observed warming temperatures in the Arctic is not supported; how can an oscillation produce a long-term warming trend? Recall the long-term military submarine record of decreasing seasonal Arctic sea ice thickness that was kept secret for over a decade? How about the ongoing collapse of Antarctic ice shelfs? Increased warming in the polar regions is an old prediction of AGW models; prediction is now reality.

    These oscillations may very well be sensitive to increased temperatures and increased heat content in the northern polar region; to say that they are the cause of the warming makes no physical sense. Such oscillations might also alter hurricane patterns, but the main driver of hurricanes is warm sea surface temperatures >27C (we can all agree on that, I hope); atmospheric conditions also need to be conducive (see the above comment on this year’s rip-snorting season). It doesn’t matter what the atmosphere does if the SST’s are too low for hurricane formation. The Landsea-Gray group pointedly ignore these basic facts. A warmer Saharan air mass seems to match AGW predictions as well, yes?

    Thus, the correct discussion should be this: How will the Arctic-North Atlantic oscillation be affected by warming temperatures? Recall the RealClimate discussion of polar amplification:
    http://www.realclimate.org/index.php/archives/2006/01/polar-amplification/
    http://www.realclimate.org/index.php/archives/2006/05/more-on-the-arctic/

    Why does this matter to long-term climate predictions? Steadily increasing Arctic warmth could have large effects on the global thermohaline circulation (THC)(particularly in the Atlantic). What does this mean? Reduced oxygen content in the deep ocean is just one consequence; wind-driven upwelling of low-O2 bottom water can have drastic effects on marine ecology and fisheries, as seen of the Oregon coast. The notion that halting the THC will freeze Britain might be true in a glacial era, but seems unlikely in a rapidly warming world due to increased heat delivery from tropical zones. What could happen next?

    Increased heat storage in the upper polar ocean leading to destabilization of shallow-water methane hydrates and massive CH4/CO2 fluxes to the atmosphere would not be good news (I’m assuming I can skip a discussion of petroleum geology and the various routes of methane formation). Accurate and comprehensive data from the Arctic is needed – did Pielke really say that it’s only 10% of the oceans, so it’s not important?

    Part II
    Media reporting on AGW:

    Meteorologists tend not to worry about the oceans since they aren’t a major factor in short-term weather, but climatologists have to study oceans and ice sheets in detail for their forecasts. However, meteorologist and climatologists could no doubt learn a lot from each other – over-specialization in academic science is an ongoing problem in many disciplines. The various tribes of scientists should spend more time working together, although all the Science Napoleons will likely view this as turf intrusion: thus, remember that humility is always a good approach when entering foreign territory.

    It is clear that the media has given a very loud voice to a handful of climate science skeptics who have made multiple conflicting statements. This is what you call results-oriented science – the desired result being scientific proof that the notion of AGW is false. Similar research can be found in pharmaceutical circles (in that case, the desired result is demonstration of the wonderful health effects of the patented compound). See, for example, the RealClimate discussions of Gray and Lindzen’s opinions:

    http://www.realclimate.org/index.php/archives/2006/04/gray-on-agw/
    http://www.realclimate.org/index.php/archives/2006/02/richard-lindzens-hol-testimony/
    http://www.realclimate.org/index.php/archives/2006/04/lindzen-point-by-point/

    In less politically charged areas of science, such opinions are (usually) gently tolerated, but since those opinions have been widely help up in the media as evidence of ‘the controversial nature of climate science’, their multiple fallacies and inconsistencies need to be pointed out (which is a real waste of time for the rest of the climate research community). Journalists and their editors, by and large, have yet to appreciate this, since they keep dredging up the same suite of skeptics for contrary opinions.

    As far as the government science bodies go, remember that the ‘political managers’ of federal science bodies have a final bottom-line concern – the gutting of their funding and the concomittant layoff of many scientists under their protection. Science isn’t supposed to be done at the whim of various political and economic interests, but that’s what’s going on. The National Renewable Energy Laboratory is a case in point; their funding has been subjected to more political reversals than I can keep track of. See also #67, #48, #57 in this thread. Very ‘sobering and disturbing’ but also fairly similar to current FDA practices. Chris Mooney’s book on this topic is worth reading.

    Part III
    Finally, a brief comment on renewable energy economics vs fossil fuel economics and the electricity system (not entirely off topic!): The goal is to use renewables to power the electrical grid as well as to produce liquid fuels. To do this will require a focus on ‘energy efficiency’ as well as massive deployment of existing technology and expanded research on new technologies. Now, this topic of energy efficiencies has been incredibly abused and misused in popular parlance (my 3% coal efficiency quote in #14, is sadly an example of this – my apologies, and see also #82 for more on the issue).

    First of all, there is always wide range of efficiencies for any given process, and you have to be very clear about defining system and surroundings. For example, you have to ship a barrel of oil halway around the world – relative to your personal energy supply, what are the most and least efficient methods? If you attach the barrel to a helium ballon and let it go, eventually the winds will blow it around the world and after some random time interval, it will appear in the desired location – a very efficient method, but not a very timely delivery. On the other hand, you can load it on an F-16 jet fighter and send it off; with a few in-flight refuelings the barrel will be delivered in record time but at a great energy cost (much more energy then could ever be extracted from the barrel of oil). So, what ‘efficiency estimate’ do you use for transporting oil? The point is this: if you every see a figure for “efficiency” without a clear explanation of the circumstances, it means absolutely nothing. This isn’t too far off-topic since thermodynamics and kinetics also are of fundamental importance in studying weather and climate, as is the definition of system and surroundings.

    Conclusion
    To sum up my post: (i) the climate skeptics are promoting junk science with respect to the hurricane-AGW story; (ii) there is a long history of scientific distortion of the AGW issue, politics are a main factor in this, and as a result the media has mostly done a poor job of reporting on climate science, and (iii) renewables are technologically capable of supplying the energy needed to support human societies.

  14. 114
    Stephen Berg says:

    Re: #111, “Surely there is contention about what caused the elevated SSTs (man vs. nature)”

    No there isn’t. The cause of elevated SSTs is identical to the cause of elevated atmospheric surface temperatures, which is, primarily, human activities, as scientific organisations such as the AGU, NAS, AAAS, AMS, EGU, WMO, CRU, and most of all the IPCC have declared.

    Here is the post-1850 global atmospheric temperature record:

    http://www.globalwarmingart.com/wiki/Image:Instrumental_Temperature_Record.png

    Here is the post-1850 global and hemispheric sea surface temperature record:

    http://www.atmos.albany.edu/deas/atmclasses/atm305/temp2.jpg

    The trends are fairly identical, only with a bit of a lag, which accounts for the differing thermal inertia of the atmosphere and the oceans. This means it is fairly safe to say that the cause of both increases is identical.

  15. 115
    Steve Sadlov says:

    RE: #114 – Care to discuss the various caveats regarding the data as represented versus as gathered?

  16. 116
    pat neuman says:

    re: 109 Steve,

    By limiting your discussion of July/August temperature averages to only one year (2006), your readers miss the increasing trends that are apparent in viewing 100 year temperature plots at northern Minnesota climate stations, particularly the average of overnight minimums.

    To view increasing average July-Aug minimum temperatures (trends) see the two northern Minnesota climate stations with the longest available high quality daily temperature records in MN (Leech Lake Federal Dam, Park Rapids 2 South) by going to summer at:
    http://pg.photos.yahoo.com/ph/patneuman2000/my_photos

    Also important… Mark Lenarz with the State Department of Natural Resources said “If you’re a moose, and it’s the middle of summer, and you’re panting, you just have a lot less time for eating.” In the end, he says, many of these moose cannot cope with the added stress. Lenarz says the moose are dying in greatest numbers â?? within a year of a very hot summer.”

    http://www.kare11.com/news/investigative/extras/extras_article.aspx?storyid=11815

  17. 117
  18. 118
    Wacki says:

    Dr Judith Curry, you said:

    The Europeans (notably ECMWF) do not have the dichotomy between forecasting and research, and weather and climate that we see in the U.S., and their forecasts are far better than those in the U.S. (particularly ECMWF).

    This is very interesting. Do you have more info on this? Any studies done? Thanks again for all of your very informative answers.

  19. 119

    Re: #114

    Dr. Curry’s whole BAMS article is about the contentiousness of the issue, including the causes behind the recent warming of the tropical Atlantic SST. I respect your argument, and even if it is the absolute and sufficient explanation, this issue is still, presently, contentious.

  20. 120
    pat neuman says:

    re 113. ike – regarding your conclusion (ii) in 113,

    The link in 117. to the Twin Cities Kare11 Climate Change story works now. Note also that Rick Kupchella, KARE 11 News, includes a link to more information on climate change. I think you will agree that the work presented by Rick is very good and doesn’t fit with your “mostly done a poor job of reporting on climate science” like other media stations.

    I think it’s important to point out that Rick created the story and website on climate change at Kare11 with no assistance from the staff at the NWS in Chanhassen MN and without help from the Minnesota climatology people. Staff at NWS and MN climatology have refused to speak out about climate change and global warming by claiming that the science is too controversial and political for them to deal with. I disagree about the science of climate change being political. Non-scientists, and many federal meteorologists, have made climate science appear political for reasons which I don’t care to go into again at this time.

  21. 121
    L. David Cooke says:

    As a general comment:

    I am finding I have more questions then answers after reading the study that is driving these comments. In reference to the three hypothesis presented in the top right hand column of the first page of the study there appears to be a problem with the logical linkage between them. As they are stated these hypothesis are each independent and not linked.

    1) the frequency of the most intense hurricanes is increasing globally;
    2) average hurricane intensity increases with increasing tropical SST;
    3) global tropical SST is increasing as a result of greenhouse warming.

    As each element, is independent it is just as likely that they are coincidental associative occurrences and are not related? Take the first statement this observation still remains in jeopardy, as the data we have publicly available with enough accuracy to trace the storm life cycle has only been available for about 10 years. The second statement other then a lack of a clear data trail and too small of a population sample is statistically constructed with two independent variables that cannot demonstrate a clear dependence. Finally, we have the third statement which this year is proving unabashedly to be false.

    Every indication is that an improved casual logical hypothetical progression should have been something more like the pattern below:

    1) Apparently, Greenhouse Warming is resulting in Global Warming.
    2) The increase of Global Warming is apparently resulting in increased global average tropical SSTs.
    3) The apparent increase in global average tropical SSTs are apparently resulting in increasing frequencies of more intense hurricanes.
    4) Therefore, Greenhouse Warming is apparently resulting in the increase of the global frequencies of more intense hurricanes.

    We can now suggest that the hypothesis chain is false. As in the chain of evidence, there continues to be an increasing CO2 component of Greenhouse Gasses, which is about a 23% contributor to Greenhouse Warming. There also appears to increasing Global Warming; however, there does not appear to be increasing SSTs in either the Atlantic or the Pacific according to the NOAA TOA or TOAST sites with regard to the ITCZ SSTs or the 20 Degree C isotherm depths. And yet, interesting enough there also does not appear to be storms now that the N. Atlantic SSTs are approaching the heat content and depth required to support them. (Of course, I could just be speaking too soon.)
    The question is why, if there is increasing Greenhouse Gases contributing to Greenhouse Warming and Greenhouse Warming is apparently contributing to Global Warming should not the SSTs be increasing? Dr. Elsner’s recent study blamed air temperature for increasing SSTs. This hypothesis simply can not be born out. The basic physics of the differences in density logically can not support it, (providing I understand my physics correctly). (Maybe there is some quirk of thermodynamics I have missed.) There simply is not enough warm air, hot enough, to warm the ocean to a depth of 80 meters. However, there is more then enough ocean to warm and humidify the air. Dr. Elsner has done an excellent job using the Granger Causality lag verification. As the conditions he identifies are a clear signal to SSTs that can support the development of an intense Tropical Storm. However, the apparent conclusion he outlines in the introduction appears to me to be flawed.

    I would suggest that looking at the original “casual” logic construct here in regards to the Curry, Webster and Holland study suffers a similar condition. I fail to see the simple ‘casual chain’ of logic in the example provided in the study. Have I missed something? Is it simply I just do not understand and my reading comprehension has failed? Or is it worse, is it that we fail to ask the correct questions and form them correctly? Is it that we simply do not have enough reliable information in regard to the questions to answer them well? Is it of political expediency that we race to attempt to extend information with unreliable data? Is it unfair that the request for funds to support good data to support good policy creation has been discarded in favor of rehashing formulas to try to squeeze good data from bad data; resulting in data saying what ever the requester wants to see?

    Dave Cooke

  22. 122
    Jeff Weffer says:

    … in any case, one year does not a trend make. comment by Marcus – 21 Aug 2006

    Then why do we want the meterologist to immediately blame global warming the instant an unusual 2005 tropical storm/hurricane season occurs.

    It seems to me that the meterologists were correct to say “There is no link right now.” Why is everyone piling on top of them saying they have been coerced by somebody to not draw the direct global warming link.

  23. 123

    Why is everyone piling on top of them saying they have been coerced by somebody to not draw the direct global warming link.

    Fundamental thermodynamics and observational evidence.

    Have you even read the papers?

  24. 124

    119- The problem is with the apparent disconnect between science data and meteorologist presenters. Basic causalities should be asked, but especially answered, there are usually none, or just one now a days, called AMO. Judith Curry gave one already well established reason why there are fewer hurricanes in #85, not in defence of AGW, but from apparent causal effect. A well informed society knowing this fact would perhaps not conclude AGW bunk because there are so few Tropical Storms/ Hurricanes this season. Not quite the same defence can be given to any Hurricane forecaster attaching AMO, for the next 20 years or so to give lots and lots of hurricanes each year because of a 0.2 C degree SST cycle, they have made a flat out prediction, which so far seems wrong, although the season is not over, they would do well to inform the public as well as Judith has done, the blame game should be dropped in favor of explaining science well.

  25. 125
    Steve Bloom says:

    Re #112: “If a noted climate scientist explains multi-year changes in ocean heat storage in terms of ‘tropical variablity’ or ‘weather’, I would suspect that any particularly intense tropical cyclone(or season, or multiple seasons) would surely also fall into this category of ‘tropical variability’.”

    Of course Gavin was discussing variability over a 2 year period, whereas Webster et al looked at 35 years. Notice a slight difference in the period? That was a very unscientific assertion for a “professional earth scientist” to make.

  26. 126
    Steve Bloom says:

    Re #115: Sure, Steve S. Why don’t you start with a citation or two?

  27. 127
    Mag says:

    Dan,
    Till now there isn’t any strong scientific background for that, otherwise we wouldn’t debate here about thoughts, opinions and personal theories. No one should claim certainty over such topic, you may review comment No.79 and see what’s behind.

  28. 128
    Bryan Sralla says:

    Re #125: Steve, thank you for engaging me on this. It is always fun to see your thoughtful comments. I would argue that another way to look at the ocean heat content is over a five year span (2000-2005) vs two (2003-2005). Over this five year time span, the latest observations appear to show that the top of the atmosphere has been in an averaged state of radiative balance. In my interpretation of the literature, it has been agreed by most of the community that the OHCA is a much more robust metric than tropical cyclone variability. Peixoto and Oort (1992) in their book on climate physics show that even for timespans of a year, this metric provides a good snapshot of the planetary radiative imbalance at the top of the atmoshpere. Tropical cyclones, even for spans of 35 years have not been shown to provide such a solid indicator of climate change.

  29. 129
    Steve Sadlov says:

    RE: #126 – the burden is on Mr. Berg. He needs to present all the qualifications and caveats regarding the data. One could start with the caveats that are right there in the text below the figures. But that would only be scratching the surface. There is a whole metatopic here.

  30. 130
    Steve Bloom says:

    Re #119: Chip, you’re forgetting your disclaimer.

  31. 131
  32. 132
    Mike Neuman says:

    I’d like to throw my 2 cents into this assessment before the debate closes. While not a frequent poster on Realclimate.org, I check in periodically when my brother Pat Neuman brings something to my attention (although I came here today on my own).

    First, I think the authors of article being discussed deserve credit for serving up the fodder for discussion. “Mixing Politics and Science in Testing the Hypothesis That Greenhouse Warming Is Causing a Global Increase in Hurricane Intensity” is a challenging undertaking.

    On the scientific issue of hurricane intensity, I didn’t think this year would see the high level of activity that we saw last year. The reason is that last year was no doubt an extreme, just like the European heat wave of 2003 was an extreme. Extremes don’t usually get repeated year-to-year. But they are more likely to be repeated as the years continue to pass since we have been on a continuous warming streak for over 30 years that shows no sign of slowing down nor does our knowledge of science give us any reason to believe that it will.

    That being said, the potential for the 2005 hurricane season in the Atlantic and the 2003 heat wave in Europe to have been repeated in immediately successive years, even with global warming, was extremely low. Any hydrologist will tell you that the probability of having two 100-year floods occur back-to-back is extremely low. When you experience one in one year, the chances are still one out of one-hundred that you will get another one of the same intensity the next year, even if the climate has become slightly more likely to produce an extreme flood.

    The issue of risking one’s own career to do the right thing on this issue – something both Pat and I have done over the past few years and suffered the consequences for as a result – deserves far more discussion than I read in the subject article or on this forum. In particularly, the article is way too kind to our mass media journalists, who it claims “are looking to develop stories that are timely and relevant, are wide in scope, have a particular thematic angle, relect conflict, and demonstrate human drama”. The fight by conscientious scientists to elevate the growing crisis of global warming into the limelight of concern over the last several years – higher that of the Iraq War and the World Trade Center catastrophe – fits all of those journalistic prerequisites to a tee. The prerequisite that it fails to meet is not even mentioned in the article – that the story must not risk the journalist’s job security, career or embarassment in any way, shape or form, as it would if there were written or unwritten orders from the “powers that be” to stay away reporting anything that particular topic.

    Scientists are one of the few groups who might be expected to assume that they have a responsibility to communicate their research findings and opinions to policy makers and the public at large when there are matters of life and death involved. Few other seem to have the ethics or the courage to do so, much less to appropriately report on it. Fear over their job security and ridicule prevent them from doing so.

  33. 133
    ike solem says:

    Re#120,

    I read the article and I agree that he did a good job. The issue of biological responses to climate change is very complicated, but the report is very well-written and includes concerns which relate to human health as well. Heat waves are just as damaging to humans as to moose, as seen by the 100+ deaths caused by the recent California heat wave. The hot nights are particularly bad, since it is difficult to cool off in humid conditions. The impacts on the natural biota mimic the impacts on the elderly. The polar bear is also being impacted, but appears to be moving south and interbreeding with brown bears; wildlife biologists have found a number of hybrid offspring recently. The biological response is well ahead of the media response, it seems.

    Those who say that increased CO2 will increase agricultural productivity are ignoring the effects of highly variable weather on crop yields; this summer’s heat wave was estimated to reduce corn yields by 10-20% as I recall from news reports from the Midwest. Furthermore, nitrogen and phosphate are generally thought to limit photosynthetic productivity, not carbon dioxide; if abundant N, P, K, Fe etc. are present than CO2 does lead to short-term increases in photosynthesis. (But the Competive Enterprise Institute’s “CO2: We Call it Life” campaign is just ridiculous).

    The solution at the photosynthetic end of the carbon equation is to halt the ongoing global deforestation and to start planting long-lived trees (think of trees as carbon sequestration devices).

    RE# 128,

    Bryan, I’m still waiting for an acknowledgement of the scientific inaccuracy of your previous comments, in which I was accused of promoting ‘junk science’ regarding the conditions under which source rocks for oilfields form (as related to the quite relevant and topical issue of reduced thermohaline circulation and bottom water hypoxia). So, are you willing to admit you were wrong publicly? Why did you want to have a ‘private email exchange’ on the topic instead? If you aren’t willing to admit when you’ve made a fundamental scientific mistake about source rock formation (that relates directly to your stated profession of hydrocarbon geology), then why should anyone listen to anything you have to say, particularly when it comes to atmospheric and ocean sciences?

    Then you go on to state the following in #128:

    “I would argue that another way to look at the ocean heat content is over a five year span (2000-2005) vs two (2003-2005). Over this five year time span, the latest observations appear to show that the top of the atmosphere has been in an averaged state of radiative balance. In my interpretation of the literature, it has been agreed by most of the community that the OHCA is a much more robust metric than tropical cyclone variability. ”

    What latest observation? What literature have you been interpreting? Why can’t you provide references? What do you mean by “the atmosphere has been in an averaged state of radiative balance”? As far as I can tell, that’s just gibberish – what datasets were ‘averaged’ and what do you mean by ‘Radiative balance’? When is the atmosphere in a state of ‘radiative imbalance’? Radiative equilibrium takes place on very fast (microsecond or less) timescales, so what on earth are you talking about?

    Obviously, people are concerned about hurricanes because of their destructive potential; increasing SST’s and decreasing sea ice and ice sheet volumes are indeed better ‘metrics’ but we are looking at hurricane frequency/intensity increases as an effect of global warming, not as metrics for global warming (and polar region temp increases are also good ‘metrics’ for testing the model predictions). You’re a professional earth scientist: what do you use to date strata brought up from oil rigs? Forams (tiny, abundant sea critters) or dinosaur bones? Hurricanes, like dinosaur bones, are of great interest to the general public – just look at the effects of Katrina to see why. Tropical SST’s have clearly been increasing – look at any study relating coral reef die-off to SST’s – there are many studies on this issue.

  34. 134

    As I wrote earlier, one must not under-estimate the intelligence found in lay persons not involved in the Climate or Met fields of endeavour

    http://www.zogby.com/news/ReadNews.dbm?ID=1161

    Majority of Americans believe that we are experiencing GW, and also think that they are linked with stronger hurricanes like Katrina. This Majority should eventually translate eventually into action, hope it will come soon.

  35. 135
    Steve Bloom says:

    Re #121: Dave, I think you need to look at all of this more carefully. For example, there’s a problem with your statement that Elsner’s recent study “blamed” increased air temps for higher SSTs. Here’s the abstract:

    “The power of Atlantic tropical cyclones is rising rather dramatically and the increase is correlated with an increase in the late summer/early fall sea-surface temperature over the North Atlantic. A debate concerns the nature of these increases with some studies attributing them to a natural climate fluctuation, known as the Atlantic
    Multidecadal Oscillation (AMO), and others suggesting climate change related to anthropogenic increases in radiative forcing from greenhouse-gases. Here tests for causality using the global mean near-surface air temperature (GT) and Atlantic sea-surface temperature (SST) records during the Atlantic hurricane season are applied. Results show that GT is useful in predicting Atlantic SST, but not the other way around. Thus GT â??causesâ?? SST providing additional evidence in support of the climate change hypothesis. Results have serious implications for life and property throughout the Caribbean, Mexico, and portions of the United States.”

    Note the use of quote marks around causes! If you would then read the study, you would see that he in no manner proposes some mechanism whereby the air heats the sea surface so as to account for the current trend of increasing SSTs. Instead he says the two are “correlated.” What that actually means is that they have a common cause, which is greenhouse warming.

    I think most of the rest of your stuff relies on similar misunderstandings, as when you say:

    “(…) the data we have publicly available with enough accuracy to trace the storm life cycle has only been available for about 10 years.” Where in the world did you get that from? Certainly data improve with time, but the metric that Webster et al made use of (maximum wind speed) is calculated from the comprehensive data base of satellite photos dating back to 1970. There’s certainly a debate about interpretation, but there’s nothing “missing.”

    “The second statement other then a lack of a clear data trail and too small of a population sample is statistically constructed with two independent variables that cannot demonstrate a clear dependence.” That just sounds like denial. Remember that the debate in the hurricane science community is only over the categorization of some storms from 1970 to 1990. I should emphasize that there is no dispute as to whether the information is available to do that job, just as to whether it has been done consistently. Webster et al state that they have looked at the data from that standpoint and believe that there is no significant problem with respect to maximum wind speed. There have been *claims* to the contrary, but no paper has yet been published showing that Webster et al’s assessment is incorrect. If you know otherwise, please inform us!

    “Finally, we have the third statement which this year is proving unabashedly to be false.” The long-term SST trend over the study period is absolutely clear. I haven’t had a chance to look at the data you refer to, but bear in mind that SST trends over such a short term are essentially weather (and like all weather metrics cannot be expected to increase monotonically), and SST trends globally should not be expected to be identical to those in the hurricane basins.

    Your last paragraph makes it seem as if you came to this issue with certain assumptions in mind.

  36. 136
    Steve Bloom says:

    Re #128: I would second Ike’s comments and also note that when you say “it has been agreed by most of the community that the OHCA is a much more robust metric than tropical cyclone variability(.)” you’ve absorbed the style but not the substance of RP Sr.’s site. To my knowledge, nobody, and certainly no climate scientist, has ever suggested using tropical cyclones as a climate metric.

  37. 137
    Jeff Weffer says:

    Has anyone actually posted/plotted all the data in the HURDAT historical hurricane dataset series. It is complicated and I don’t have time to collate it,

    But someone really should plot it BY YEAR going back to 1850 and then maybe someone can ACTUALLY state that hurricanes are increasing.

    So far we’ve just picked out a few years, here and there, and a few averages over a few periods.

    [Response: You can find the annual number of total named Atlantic TCs back to 1870 here. – mike]

  38. 138
    Bryan Sralla says:

    Re: #136 (you’ve absorbed the style but not the substance of RP Sr.’s site.)

    Steve, help me out a little here. What substance have I missed?

    (To my knowledge, nobody, and certainly no climate scientist, has ever suggested using tropical cyclones as a climate metric.)

    Sincerely, I do not follow this. This seems to me exactly what this discussion is about. If increasing severity of tropical cyclones were not being touted as such a measuring stick of increased warming, why are we having this discussion in the first place? Are you trying to make the point that they are not related subjects?

  39. 139
    Jeff Weffer says:

    Mike, that data does not appear to be from the HURDAT set.

  40. 140
    Bryan Sralla says:

    Re: #133 Q:(What latest observation?)
    A: Lyman (2006)

    Q:What literature have you been interpreting? Why can’t you provide references?

    A:Peixoto (1992), Levitus (2000), Barnett (2001), Pielke (2003), Hansen and Schmidt (2005)here: http://www.realclimate.org/index.php?p=124, and here: http://www.realclimate.org/index.php?p=124

    Q:What do you mean by “the atmosphere has been in an averaged state of radiative balance”?

    A:The volume integral (heat balance equation) as presented in Pielke (2003) http://blue.atmos.colostate.edu/publications/pdf/R-247.pdf suggests that the changes in ocean heat storage averaged over a year are a snapshot of the radiative imbalance at the top of the atmosphere. According to the latest observation by Lyman (2006)
    http://www.realclimate.org/index.php/archives/2006/08/ocean-heat-content-latest-numbers/ the heat content of the oceans is virtually unchanged since 2000, hence my comment.

  41. 141
    Bryan Sralla says:

    Re: #133. Ike, my e-mail is sralla@prodigy.net. I again offer my invitation to take this discussion of petroleum source rocks offline. If after this time, you want to cut and paste my offline response to you onto this website, you are more than welcomed to do so.

  42. 142

    By gosh you are right, Steve (re # 130):

    To all–posts #111 and #119 were made by someone (me) who has been, to some degree, funded by the fossil fuels industry since about 1992. So, feel free to disregard them…

  43. 143
    L. David Cooke says:

    Ref #135

    Hey Steve;

    I am afraid I did come to the table with an agenda. I have been around this discussion for several years and as a common layman have been studying the characteristics of climate change since around 1969.

    I had read Dr. Elsner’s study and was amazed at his use of the Granger Causality Test of the data. This was quite similar to a study (Sun et al 1996)in which they applied the Granger Test of a A GT against the apparent global average CO2 levels. (They proposed similar to Dr. Hansen in his 2005 work, that there was a lag in the coupling of the GHG contribution and the rise of terrestrial solar insolation content.) Dr. Umberto Tricca returned with an evaluation of the Sun study and noted that there are several issues with the accuracy of the study, one being the issue of a moving average. In which when you have values of increasing medians you actually should not apply a normal Law of large number or Bell Curve type distribution analysis to the data. The unspoken indication from Dr. Tricca is that the comparison should be against the linear regression and the R2 values from period to period and not the values themselves. (Would this mean that the majority of the current statistical evaluations may have an inherent flaw?)

    The point is though Dr. Elsner appears to have done a great job with the analysis; however, to claim a correlation where it is more likely an association is my primary concern. (This is also the concern I am having with the (Curry et al 2006) current study.) That there is a one way associative cause and effect logic chain would appear to specify that increased SSTs are the result of increased ambient GW. Is that different from what you see in the conclusion?

    As to the comment of storm life cycle I am speaking of having absolute Doppler radar images of he storms from the development of the tropical wave off the Cape Verde islands to it eventual termination as a tropical storm somewhere in the Mid-North Atlantic maritime regions. (Meaning direct measurement of the whole storm and not derived or small samples of data.) When coupled with the new images from both the Calipso and CloudSat, there now exists a possible 3D view of the atmosphere and a clear indication that we really may not understand the adiabatic character of water vapor nearly as well as had been indicated in the past.

    As to the hurricane community, I have had an friendly association with one of the original hurricane hunters. This spiked my interest at the age of nine and has been one of the constants in my life, (That no matter what happens today tomorrow will likely be different, though the new day may have a starting place somewhere in what has happened the day before).

    At what point do you categorize a storm appears to be of great debate. When you do not have direct evidence then the character of Dr. Landsea’s analysis seems appropriate in measuring the data from what you do know, landfall. This way you are not arguing over who has the better model or has the more detailed estimation; in this case, you are comparing data. Now the question is do you have enough samples to create a statistically valid analysis? If you want to categorize the data according to latitude of landfall, or consider associative cyclonic or anti-cyclonic pressures zones that could have fed/destroyed the storms potential, or if associative pressure zones are not ground to space; but mid-level and hence could negatively affect the storms development, as long as you have the measured data that would be useful.

    Finally, the SSTs, this has been a new opportunity for me, to observe the NOAA robotic buoy data that covers the ITCZ and has been a welcome opportunity to analyze the character of the potential of La Nina this past spring. When coupled with the NCDC SRRS analysis and forecast charts it is amazing the accuracy that even I, an ignorant layman, can develop in predicting long term or seasonal storm development and the likely contributors. As to a study, sorry there isn’t one to my knowledge; however, the data is clearly there for all to see, I like that!

    Again Steve, you are correct I do come to the table with many questions; however, unlike some I am inclined to believe these are worthy of answers. (I guess I am just a little bit biased in my opinion.) I appreciate your assistance in trying to help me straighten out my misunderstandings; however, it does not seem to have helped much. I really am not trying to be hard headed or have a un-retractable opinion as I have no skin in this game. I am more interested in the correct application of science in search of answers. If it is that I am simply too ignorant to teach, my apologies, please direct me to some supporting texts so that I can learn to talk intelligently about the subject.

    Dave Cooke

  44. 144
    John Bolduc says:

    RE #134, the Pew Center poll conducted last June is enlightening. 41% viewed global warming as “very serious” and 33% said “somewhat serious”. Only 41% agreed global warming is due to human activity. So most Americans appear to believe global warming is a problem, but a majority does not believe it is due to human activity. So convincing the American public that GHG emissions need to be reduced remains to be accomplished, according to this poll. You can see the poll results at http://people-press.org/reports/display.php3?ReportID=280.

  45. 145
    Steve Sadlov says:

    RE: #131 – I was not asking you for a bunch of quickie links. I was asking you to personally state, in your own words, caveats. Was this not clear?

  46. 146
    Stephen Berg says:

    Re: #145, “I was not asking you for a bunch of quickie links. I was asking you to personally state, in your own words, caveats.”

    Mr. Sadlov, why do I need to when a description of the data is presented here:

    http://www.globalwarmingart.com/wiki/Image:Instrumental_Temperature_Record.png

    http://www.atmos.albany.edu/deas/atmclasses/atm305/temp2.jpg

    Also, you can easily access the papers of reference and read what caveats exist in better and clearer words than I could regurgitate.

  47. 147
    Jerry Steffens says:

    Can we please maintain a respectful tone?

  48. 148
    Stephen Berg says:

    Steve S., please see the following PPT file which shows a correlation between Atlantic SSTs and Tropical Cyclones.

    http://www.youpload.com/files/general/0f9a3c8e9d/atlantic_sst_tc_correlation_ppt_atlantic_sst_tc_correlation_brief_powerpoint.htm

    Data is from:

    http://www.meteo.psu.edu/~mann/eos06/

  49. 149
    Steve Sadlov says:

    Caveat: “Incorporating these uncertainties, Foland et al. (2001) estimated the global temperature change from 1901 to 2000 as 0.57 ± 0.17 °C, which contributed to the 0.6 ± 0.2 °C estimate reported by the Intergovernmental Panel on Climate Change [1].”

  50. 150
    Harold Brooks says:

    Re: 137

    You can’t just plot the number of tropical storms per year without considering the inhomogeneities in the data. The Hurricane Research Division cautions against doing climatological studies of even the US landfalling data prior to 1900 in most of Florida, for instance. After that, there were large changes in data collection, most notably recon flights starting in the mid-1940s.

    Even in the recon flight era, some significant changes occur. If you look at the location of maximum intensity for each storm in the HURDAT database, since ~1962, the fraction of storms reaching their maximum intensity east of 60 W has been 0.6. Prior to that, it’s 0.8. It’s possible that there was an abrupt change in behavior then, but it’s also likely that changes in observational strategy took place. One hypothesis would be that the westernmost storms have been relatively consistently observed for a long time, but that the easternmost ones haven’t. If so, that would increase the number of storms in the mid-40s to early 60s by about 30%, compared to the official record. I’ve already noted in this thread (#23) that there are differences in the database around 1950 compared to now-Atlantic storms that don’t make landfall are much less likely to be rated Cat 3 or higher than they were 50-60 years ago.

    It’s important to know the limitations of the observational data sets for events that depend on special efforts to collect the observations, such as tropical storms. For instance, even today, in the absence of recon flights, different groups will get different intensity estimates. At one point during Cyclone Monica’s life near Australia this year, the US Naval Research Lab estimated the central pressure at 879 mb, associated with winds of 180 mph, while the Australian Bureau of Meteorology had it at 915 mb at the same time (Jeff Masters’s blog). Both groups were using mostly satellite information at the time. I have no idea what truth is in that case.


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