Dueling papers on Tropical Cyclone Frequency

Who to believe? One paper/press release says TC’s are occurring more frequently, another says they aren’t. I tend to believe the latter, because there seems to be more supporting data from other sources for it, such as Dr. Ryan Maue’s tropical cyclone research. See below.

The Southeastern United States has experienced an increasing number of large storm surges from tropical storms since 1923. The photo in the background shows the storm surge from Hurricane Eloise, which hit Florida in 1975. Credit: Graph: A. Grinsted /Photo: NOAA

First, from the University of Copenhagen

Tropical cyclones are occurring more frequently than before

Are there more tropical cyclones now than in the past? – or is it just something we believe because we now hear more about them through media coverage and are better able detect them with satellites? New research from the Niels Bohr Institute clearly shows that there is an increasing tendency for cyclones when the climate is warmer, as it has been in recent years. The results are published in the scientific journal PNAS.

How can you examine the frequency of tropical cyclones throughout history when they have not been systematically registered? Today cyclones are monitored from satellites and you can follow their progress and direction very accurately. But it is only the last approx. 40 years that we have been able to do this. Previously, they used observations from ships and aircraft, but these were not systematic measurements. In order to get a long-term view of the frequency of cyclones, it is necessary to go further back in time and use a uniform reference. Climate scientist Aslak Grinsted of the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen therefore wanted to find some instruments that have stood and registered measurements continuously over a long period of time.

The study is based on data from monitoring stations along the Eastern Seaboard of the United States, where the daily tide levels have been recorded all the way back to 1923. Rapid changes in sea level show that there has been a tropical storm. The map shows cloud cover and ocean temperatures when Hurricane Katrina hit New Orleans in 2005. Warm colors show ocean temperatures exceeding 28° C which can strengthen hurricanes. Credit: Background image: NASA/GSFC

Correlation between sea levels and cyclones

“Tropical cyclones typically form out in the Atlantic Ocean and move towards the U.S. East Coast and the Gulf of Mexico. I found that there were monitoring stations along the Eastern Seaboard of the United States where they had recorded the daily tide levels all the way back to 1923. I have looked at every time there was a rapid change in sea level and I could see that there was a close correlation between sudden changes in sea level and historical accounts of tropical storms,” explains Aslak Grinsted.

Aslak Grinsted now had a tool to create statistics on the frequency of cyclones that make landfall – all the way back to 1923. He could see that there has been an increasing trend in the number of major storm surges since 1923.

Correlation between cyclones and climate

Together with colleagues in China and England, he then looked at the global temperatures over the period to see whether there was a trend for a higher frequency of cyclones in a warmer climate. The global temperature has increased 0.7 degrees C since 1923, but there are variations. For example, there was a warm period in the 1940s but the temperature has really risen since 1980.

“We simply counted how many extreme cyclones with storm surges there were in warm years compared to cold years and we could see that there was a tendency for more cyclones in warmer years,” says Aslak Grinsted.

But not all cyclones are equally harmful and those with the highest storm surges tend to cause the most damage. Cyclones with a strength like Katrina, which hit the New Orleans area in 2005 and caused devastating floods and thousands of deaths, make landfall every 10-30 years on average.

“We have calculated that extreme hurricane surges like Katrina are twice as likely in warm years than in cold years. So when the global climate becomes 3 degrees warmer in the future, as predictions show, what happens then?,” reflects Aslak Grinsted.

http://www.nbi.ku.dk/english/

###

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Then there is this paper just published in GRL:

Decreasing trend of tropical cyclone frequency in 228-year high-resolution AGCM simulations

Masato Sugi and Jun Yoshimura

We conducted 228-year long, three-member ensemble simulations using a high resolution (60 km grid size) global atmosphere model, MRI-AGCM3.2, with prescribed sea surface temperature and greenhouse gases and aerosols from 1872 to 2099. We found a clear decreasing trend of global tropical cyclone (TC) frequency throughout the 228 years of
the simulation. We also found a significant multidecadal variation (MDV) in the long term variation of Northern Hemisphere and Southern Hemisphere TC count in addition
to the decreasing trend. The decreasing trend and MDV in the long term variation of TC count correspond well to a similar decreasing trend andMDV of upward mass flux averaged over the TC genesis region and active TC season. It has been shown that the upward mass flux decreases primarily because the rate of increase of dry static stability, which is close to that of surface specific humidity, is much larger than the rate of increase
of precipitation, which is nearly the same as that of atmospheric radiative cooling. Thus, it is suggested that the decreasing trend of TC count is mainly caused by the decreasing trend of upward mass flux associated with the increasing dry static stability.

Citation: Sugi, M., and J. Yoshimura (2012), Decreasing trend of tropical cyclone frequency in 228-year high-resolution AGCM simulations, Geophys. Res. Lett., 39, L19805, doi:10.1029/2012GL053360.

[...]

Summary

We conducted 228-year long, three-member ensemble simulations using a high resolution (60 km grid size) MRIAGCM3.2 with prescribed SST and GHG and aerosols from 1872 to 1999. We found a clear decreasing trend of global tropical cyclone (TC) count throughout 228 years of the simulation.

We also found a significant MDV in the long term variation of TC count in NH and SH in addition to the decreasing trend. In order to explore the cause of the decreasing trend of
TC count, we examined the long-term variation of upwardmass flux. We can see a decreasing trend of tropical mean annual average upward mass flux during the 21st century, but the decreasing trend is not so clear in the 20th century. However,
the decreasing trend andMDV is clearly seen if the mass flux is averaged over the TC genesis region and active TC season. It has been shown that the decreasing trend andMDV in the long term variation of TC count well correspond to a similar decreasing trend and MDV of upward mass flux averaged over the TC genesis region and active TC season.

[16] We examined a possible reason for the decreasing trend of upward mass flux. It has been shown that the upward mass flux decreases primarily because the rate of increase of dry static stability, which is close to that of surface specific humidity, is much larger than the rate of increase of precipitation, which is the same as that of atmospheric radiative
cooling. Thus, it is suggested that the decreasing trend of TC count is mainly caused by the decreasing trend of upward mass flux associated with the increasing stability.

Figure 2. 11-year running average of ensemble mean of (a) TC count for NH TC genesis region (ocean between 5N and 30N) and for the active NH TC season (July–October), (b) mean upward mass flux intensity and (c) total upward mass flux. Orange curve in Figure 2b and green curve in Figure 2c indicates upward mass flux calculated by equation (1). (d–f) Same as in Figures 2a–2c but for SH TC genesis region (ocean between 5S and 30S) and active SH TC season (January–April).

[17] So far, there is no observational evidence indicating a clear decreasing trend of global or hemispheric TC frequency as simulated by the model. We have noted that in our simulation the decreasing trend of western Northern Pacific TC count is the main contributor to the NH TC count decreasing trend, while the MDV in theNorth Atlantic TC count is mainly contributing to the MDV of NH TC count (figure not shown). Considering the large uncertainties in the regional TC frequency trend in the models as well as the observation, we should first compare the model simulation and observation in western North Pacific and North Atlantic regions, where relatively reliable long historical observation data are available.

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Dr. Ryan Maue comments:

Current global TC numbers have remained quite flat at around 85 for the past 40-years but with very large variation year-to-year. e.g. my old FSU website graphic.

They note the current average is 84.8

I’d say this paper is consistent with what many think — fewer storms in future, but more intense. However, a 60-km grid scale model is just a first crack at the problem, hence the GRL publication.

I suspect they will attempt a 12-km Earth simulator type study ASAP.

Their paragraph [17] is spot on — I’d say this paper is quite good overall.

==============================================================

Full paper here: http://www.leif.org/EOS/2012GL053360.pdf

Thanks to Dr. Leif Svalgaard.

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49 Responses to Dueling papers on Tropical Cyclone Frequency

  1. steveta_uk says:

    “We have calculated that extreme hurricane surges like Katrina are twice as likely in warm years than in cold years. So when the global climate becomes 3 degrees warmer in the future, as predictions show, what happens then?,” reflects Aslak Grinsted.

    I assume that the “warm years” he refers to were warm in the area where the cyclones occured. Since the power that drive a cyclone involves the temperature difference between the warm energy supply and the cooler sink, and since we are told that a warmer world should be most obvious in the colder regions, then logically his own research would indicate a reduction in future extreme storms.

    Logic fail, I think.

  2. wayne says:

    I’m starting to believe that ANYthing with a big up tick around the time of satellite / computer / electronics / cell phone / helicopter / technology burst is due to that burst itself, detecting and reporting frequency, and is to be looked at with a very skeptical eye indeed!

  3. morbidangel says:

    So… Models > Observations?

  4. Peter Miller says:

    The bottom line, as we all know, is that global warming is the cause of everything bad.

    So, global warming causes both more and less tropical storms – for the alarmist, it does not really matter, as long as they can claim both cause and effect.

    For example, the hurricane referred to below was definitely not caused by global warming (1780 was in the middle of the Little Ice Age). However, if it occurred today, alarmists would obviously conclude it was caused by global warming and definitive proof of the existence of CAGW.

    http://www.google.co.uk/url?sa=t&rct=j&q=hurricanes%20greatest%201800s&source=web&cd=2&cad=rja&sqi=2&ved=0CCUQFjAB&url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FGreat_Hurricane_of_1780&ei=4RF9UJm1HrCA0AWg-4HADg&usg=AFQjCNHwqUMhscis34x30EfOOozXfD4kKw

  5. TerryT says:

    ““Tropical cyclones typically form out in the Atlantic Ocean and move towards the U.S. East Coast and the Gulf of Mexico.”

    In South East Asia and Australia they don’t, and we do get our fair share of them.

  6. SanityP says:

    Guess which “type” of paper that will be trumpeted by the MSM churnalism, the pro or the con?

  7. Bloke down the pub says:

    When it comes to choosing between models and observations you know which one is most likely to get the nod here. I’m suprised though that in the 1920′s they weren’t able to check against local weather reports in newspapers and had to rely on guesses based on sea level measurements.

  8. Katrina was a Cat3 event so not actually very severe. The problem, as we all know, was the levee failure. Had these been ”up to the job” the New Orleans flooding would not have happened. Certainly news about hurricanes sweeping up the E coast of the US causing death and destruction are, thankfully, very few and far between.

  9. GeoffM says:

    Off topic, but Al Gore is speaking at a closed meeting in Gibraltar this month and Lord Monckton is responding by hosting an open forum at the same location with unlimited questions on the 22nd of this month.

    If anyone is in the area – I hope to meet up with you!

  10. FundMe says:

    What I understand from the article in PNAS is that they have used the storm surges along the coast of the USA (Because they have long lived tide gauges) as a method of counting the frequency of tropical storms. They then correlate these storm surges to warm years using Global Temperature (air,SST?) whereas Hurricanes form in very specific areas and only a local SST correlation would be appropriate. I cannot read further to see how they deal with this because the Article is pay walled. Is there a correlation between Global surface air temperature and the SST in the Gulf of Mexico or the Carib sea? I know they are saying that there are more storm surges in Global warm years I just wonder whether they have checked their figures against lunar/tidal effects etc? I hate pay walls but this looks like it wont be worth 10c never mind $10 to read.

  11. Don K says:

    Who to believe?
    =====
    Maybe neither?
    Points against the Copenhagen paper
    .The North Atlantic is not necessarily representative of the tropical seas as a whole?
    .Tidal gauge data from the East Coast of the US goes back well into the 19th Century. Why did they stop at 1923? Would a longer timeframe confirm their findings?
    .How do they distinguish between tropical storms and strong non-tropical coastal storms (i.e. NorthEasters? My impression is that the seasons for the two overlap.
    .The article specifically refers to “landfalling hurricanes”. Surely, from the 1920s on, we have good records of those. They aren’t all that easy to overlook. Maybe a press release issue(?)

    Points against the Japanese paper.
    .It’s a simulation. Someday we’ll have climate models that work. But, today?

    Interesting papers – both. But incontravertible truth? I doubt it.

  12. Tom B. says:

    So let me get this straight… The actual observations over the last 40 years are flat. one study shows increasing storms from ‘storm surge’ statistics, the other shows decreasing storms from a ‘whole earth simulation’? But the actual observations over the last 40 years are flat?

    Shouldn’t the ‘observational data’ trump the ‘storm surge’ and ‘simulation’?

  13. Rob says:

    Update the Southeastern data. For the most recent 7-years(2006-2012) there has been absolutely nothing of significance. NO major hurricane strikes at all. Very unusual…

  14. HenryP says:

    So when the global climate becomes 3 degrees warmer in the future, as predictions show, what happens then?,” reflects Aslak Grinsted.
    Henry says
    Well, that is not going to happen, but the peaks around 1930, 1970 and 2010 correspond with a relative constant speed of cooling or warming, i.e little acceleration either way, sitting either near the bottom or near the top of the sine wave curve:
    http://blogs.24.com/henryp/2012/10/02/best-sine-wave-fit-for-the-drop-in-global-maximum-temperatures

    So, we are probably going to see a few more strong storms in the next few years…..

  15. P. Solar says:

    Tom B says: Shouldn’t the ‘observational data’ trump the ‘storm surge’ and ‘simulation’?

    Yes and it’s cyclic above all else:
    http://i48.tinypic.com/29ni90i.png

    Now whether AMO has already peaked as in 1880 or will continue on a plateau for the next 20y or so remains to be seen.

  16. Gamecock says:

    As most Atlantic hurricanes do not make landfall, I don’t see coastal tidal surges as an adequate proxy for measuring storm frequency and/or intensity. Nor do we know how widely dispersed the measuring stations are.

  17. Bill Marsh says:

    @Tom B

    You apparently don’t understand Climate Science. Observational data is the data of last resort and should be disregarded in favor of any simulation or proxy. What are you going to believe, what the computer program tells you or what your lying eyes do?

  18. ImranCan says:

    “Aslak Grinsted now had a tool to create statistics on the frequency of cyclones that make landfall – all the way back to 1923. He could see that there has been an increasing trend in the number of major storm surges since 1923.”

    Slightly bizarre considering that if you look at the US Eastern seaboard where the supposed correlation between sea level surge and cyclones was created, the ACTUAL cyclone hits over time show absolutely no steady increase over time. Hurricane hits on the USA have maximum numbers in the 30′s, 40′s and 50′s with next highest numbers being in the 1870′s and 1890′s.

    Why ignore the actual data ?

  19. Louis Hooffstetter says:

    “I have looked at every time there was a rapid change in sea level and I could see that there was a close correlation between sudden changes in sea level and historical accounts of tropical storms,” explains Aslak Grinsted.

    Really?

    So was every Nor’easter and spring tide interpreted as a tropical storm?

  20. Jim Clarke says:

    Don K is right on. There is no mystery to the number of landfalling storms in the US last Century. Peak winds were likely under reported until the latter part of the century, but the storm would not have been missed. Tides, on the other hand, can vary a great deal from one storm to another, depending on the speed, angle of approach and the size of the wind field with the storm. As such, tides do not make a very good proxy for determining the strength and frequency of hurricanes.

    The first article is just stupid. The second is a model with the assumption of 3 degrees warming. Consequently, neither one is worth much.

  21. Joseph Bastardi says:

    Dr Maue is spot on right.. end of story

  22. vukcevic says:

    P. Solar says:
    October 16, 2012 at 4:28 am
    Yes and it’s cyclic above all else:
    http://i48.tinypic.com/29ni90i.png
    Now whether AMO has already peaked as in 1880 or will continue on a plateau for the next 20y or so remains to be seen.

    Yes,it’s cyclic above all else. Dr. J. Curry uses the AMO as a base for her cyclone prediction sideline (for insurance companies). We had interesting exchange on this one
    http://www.vukcevic.talktalk.net/AHA.htm
    her comment:’ the 15 year lag is the main challenge here, but you have a plausible explanation’
    Since than the 15 year delay between atmospheric pressure and the AMO has been verified in the Geo-solar cycles, and apparently some AGW theorists WRONGLY attribute it to the CO2 factor. But that can not be correct since the delay appears in the de-trended natural oscillations as far back at 1700s, as it can be clearly seen in the direct coincidence of the geo-solar cycle and the stalagmite build up:
    http://www.vukcevic.talktalk.net/AMO-recon1.htm
    AMO and N. Hemisphere temps prospect:
    Solar magnetic cycle and the geomagnetic ripple around 2000 were fully in phase, but are currently drifting slowly out of phase. If the last 150 years long correlation holds
    http://www.vukcevic.talktalk.net/GSC1.htm
    (see no reason why it shouldn’t) then the natural variability in the N. Hemisphere would suggest, as the phase difference increases, more rapid decline towards the base levels reached in the 1970s. Effect of the declining sunspot count would indicate less intense periodic upward/downward bursts. The critical factor across the decades to come is the phase difference rather than amplitude of the sunspot count

  23. Tom in Florida says:

    John Marshall says:
    October 16, 2012 at 2:11 am
    “Katrina was a Cat3 event so not actually very severe. The problem, as we all know, was the levee failure. Had these been ”up to the job” the New Orleans flooding would not have happened.”

    Katrina was a Cat 5 while in the Gulf of Mexico and only decreased to a Cat 3 shortly before landfall. The storm surge was a Cat 5 surge and that is why the destruction all along that coast was so bad. While New Orleans garnered most of the coverage, the most destruction was farther east along that coast, which you apparently do not know. You may want to ask those people if it was “not actually very severe”.

  24. H.R. says:

    If one were to use storm surge data for a proxy, how does one distinguish between the effects of say, three tropical depressions here and there off in the Atlantic and one Cat 2 storm swirling around out there? Other commenters have pointed out various causes for storm surges which would bias the count. It’s probably trivial to throw out ‘false surges’ using data from the satellite era, but how does one figure out what ‘false surges’ to throw out prior to the satellite era?

    Now the model; if the model closely tracks past observations, they just might have the makings of a good model. If the model continues to closely track observations, they probably do have a pretty good model. If the model continues to closely track observations over long periods then they might really be on to something. Let’s wait 30 years and see how their model stacks up.

    Ever since I was introduced to the ACE by Dr. Ryan Maue here on WUWT, I really prefer ACE to any storm counts. AFAICT, neither of the methods in this post will get the storm counts right.

  25. ShaSha says:

    @ Bill Marsh,
    Maybe that is the problem with Climate Science!
    How can we rely on computers to tell us what is going on? a computer and simulations are all produced by man and the algorithms that he has produced, and so shouldn’t the responses given by a computer be biased towards that?

    Observational data should not be the last resort! It should be used in order to strengthen the simulations.

    “You must understand that seeing is believing, but also know that believing is seeing.” – Denis Waitley

  26. Gamecock says:

    Mr. Marshall is correct to the extent that the amount of damage does not necessarily correlate to the intensity of the storm.

    The primary cause of the flooding in New Orleans was inadequate design and construction of the levy system by the Corps of Engineers. Had they done a good job, Katrina would have been just another little hurricane to NO. TiF is correct that there was significant damage east of NO, but NO got all the news coverage.

  27. DirkH says:

    Both junk. The many ways in which climate science can fail is mindboggling. (see also: Sturgeon’s Law)

  28. Jeff Alberts says:

    I tend not to rely on simulations because, well, they’re not reality.

  29. Jeff Alberts says:

    The primary cause of the flooding in New Orleans was inadequate design and construction of the levy system by the Corps of Engineers.

    Actually it was because of part of the city and surrounding area being below sea level.

  30. HenryP says:

    P.Solar says
    Now whether AMO has already peaked as in 1880 or will continue on a plateau for the next 20y or so remains to be seen.
    Henry says
    I reckon you will see a drop, big. About -0.4 from 2000-2018. I hope it is not more.
    //wattsupwiththat.com/2012/10/13/report-global-warming-stopped-16-years-ago/#comment-1110097

  31. John says:

    Whether there has been an actual increase in tropical cyclones (TCs), or whether there has merely been an increase in our ability to detect them, is a subject that Chris Landsea of NOAA has been researching steadily over the years.

    Here is a link to his 2010 paper on the subject, in which he and his co-authors suggest that the detected increase in TCs is most likely due to better detection techniques:

    http://www.aoml.noaa.gov/hrd/Landsea/landsea-et-al-jclim2010.pdf

    Readers may remember that Landsea famously resigned from the IPCC because in his view the IPCC was no longer an unbiased scientific body.

    This new paper of his determined that of the ten most recent cat 5 storms, the technology available in 1944-1953, the first decade of aircraft reconnaissance, would have classified only two of these hurricanes as cat 5:

    http://www.aoml.noaa.gov/hrd/Landsea/CAT_5_PAPER.pdf

    All of Landsea’s papers can be found at:

    http://www.aoml.noaa.gov/hrd/Landsea/landsea_bio.html

    This NOAA press release from 2009 also says that the “increase” in detected tropical storms seems to be due to better detection methodologies:

    http://www.noaanews.noaa.gov/stories2009/20090811_tropical.html

    It says the following, in part:

    “Several storms in the last two seasons, including 2007’s Andrea, Chantal, Jerry and Melissa and 2008’s Arthur and Nana, would likely not have been considered tropical storms had it not been for technology such as satellite observations from NASA’s Quick Scatterometer (QuikSCAT), the European ASCAT (Advanced SCATterometer) and NOAA’s Advanced Microwave Sounding Unit (AMSU), as well as analysis techniques such as the Florida State University’s Cyclone Phase Space.”

    Finally, here is a site showing hurricane strikes on the US by decade, and categorized by intensity, since 1851:

    http://www.nhc.noaa.gov/pastdec.shtml

    The decades with the most strikes by major (cat 3,4, and 5) hurricanes, in descending order, were 1941-1950 (10 such storms), 1891-1900 and 1951-1960 and 1931-1940 (three way tie with 8 each). The decade of the 2000s is incomplete, missing Katrina, Rita, etc., but from 2001 through 2004 there were 3 such storms.

  32. alex the skeptic says:

    I read about the ‘increasing tropical cyclone’ report just yesterday in Science Daily. I take a look at this online science news often, so as to have an idea of what our PhD’s are on about. They are mostly about second rate or third rate science, if not junk as this ‘increasing TC’ report is. It boggles the mind to try to quantify the amount of money spent on financing this vast quantity of ‘science’ , and it makes me realise that these days it is the quantity that matters not the quality.
    ‘Never mind the quality, feel the width’ is the essence of our time’s post normal science, and with all that vast amount of billions spent on (pseudo) scientific research I am still waiting to see the following news in Science Daily:
    >The ITER project comes on stream producing cheaper electrical power
    >A definite cancer cure has been developed
    >Vaccine for tooth decay is now on sale.
    >Cure for nicotine addiction is available at the chemist’s
    >Effective cure for drug addiction has been approved by the FDA
    >…Common cold
    >and all the other maladies that we experience along our life.

    But I m still waiting.

    During the first half of the last century, with much less money available to scientists, we had much more scientific discoveries than the second half of the century when lots of money was available to many more scientists.

    But then we have to save the planet from a 2C temperature rise in 100 year’s time. Do I laugh or cry?

  33. Rud Istvan says:

    A PNAS peer review fail larger than the US crop yields fiasco posted here earlier this year. There is no need for a proxy for data that is easily and directly ascertainable, and which (as to storm count, if not storm intensity details) is inherently accurate. It is self evident that the US eastern seaboard is densely populated, and has bee for hundreds of years. One can check newspaper records of tropical storm landfalls, even if earlier meteorological records are not exact. The count varies, but there has been no general increase in land falling tropical storms. So the tide gauge proxy is faulty. So the paper is faulty. And the simplest critical thinking should have pointed this out. GIGO

  34. atheok says:

    Hmmm. Smoothed data, fill in some gaps, down sample, remove annual cycle, normalize seasonal cycle, estimate seasons, smoothed again with a “…180-dlong
    robust loess filter…”, discard samples based on speculation, combine separate locations into one record, discard samples based on speculation, rescale… In other words it is another speculative third hand proxy fit giving “…more robust…” findings. In a court of law, hearsay is not evidence.

    Real world findings? Maybe before they got to it. That they verified it against some genuine storms does not mean the entire record is valid. In an engineer’s view, a comprehensive test sample would’ve been devised before manipulating the data so that valid after tests could be verified. Any miss would invalidate the results and send them back to the blackboard.

    It is also interesting that they do not publish or provide linkages to the raw tidal data.

    The second study is a simulation. Interesting, but…

    I’ve occasionally wondered. Predating the English colonies in America up to the Revolution; the Eastern Atlantic and Gulf of Mexico gained notoriety as graveyards for ships. Treasure seekers, both beach combers and divers bank on finding the remnants of many of these ships. In spite of efforts to avoid the worst season for Tropical Storms, Spain lost significant resources carrying booty back to Spain.

    Yeah, records are scanty at best, but either there were a lot of unlucky ships or there were cycles of severe Tropical Storms in less documented times.

  35. Rud Istvan says:

    Further practicing the Arts of Truth, J. Climate has released on line a peer reviewed preprint analyzing a century of landfalling tropical cyclones world wide. No trend. See Weinkle, Maue, and Pielke Jr. , historical global tropical cyclone windfalls (2012).
    North Caroline lists every landfalling tropical storm since 1857. Posted on line. No trend. The PNAS paper should not have passed peer review for logical reasons alone already noted. So this becomes a good example of pal review, symptomatic of what appears to be fundamentally broken ‘climate science’.

  36. lurker, passing through laughing says:

    Once again AGW prmoters abuse a proxy until they get the results they want.

  37. Don K’s (3:36 am) comments are spot on. The tidal gages are a proxy for land falling storms (or near misses). These are not subtle events. In fact, the auther uses historical accounts to test whether gaps in the tidal records are the result of storm damage or other cuases.

    The paper may be behind a paywall, but a methods a PDF on Supporting Information is in the open at pnas.org.

    Of the two papers, I am naturally inclined to pay greater heed to one based upon observations (Grinsted) than one that is models all the way down. But it looks like Grinsted beats a confession out of the data.

    [Methods: 1.d) Remove the annual cycle by division. The different tidegauge locations have different sensitivities, due to local effects such as bathymetry, and normalizing by the seasonal cycle brings the records to a common reference. The background seasonal cycle is determined from the second percentile of data within a moving 21-d-wide seasonal slice. The estimated seasonal cycle is smoothed using a 180-dlong robust loess filter with periodic boundary conditions.

    Mind you, they are doing all this on only six tidal stations (Galveston, TX; Pensacola, FL; Key West, FL; Mayport, FL; Charleston, SC; Atlantic City NJ). Why these? As other have pointed out, Noreaster storms can show up in the tidal record, particularly in the Atlantic City gage.

    That “Remove… by division” raised a red flag. Dividing by small numbers under uncertainty is a great way to reduce the signal/noise ratio.

    The “background seasonal cycle” using a “21-d-wide seasonal slice” to me only makes sense if the multi-year data was folded so that a 21-day window is looking at 21 days * 85 years stacked. I would like to see the trend and uncertainty in the z (stack) dimension as a funciton of day. And why pick 21 days, when the lunar cycle is 28 days? 27 or 29 would be a better seasonal window.

    In discussing gaps in the gauge records

    It is implausible that storms passing close to tide gauges were not well documented.

    Yeah. Which begs the question why the documented storms do not serve as another (better?) data source. He goes on to say there were gaps in the tidal records, but only 8 storms were deemed responsible.

    These gaps in the tide-gauge records quite likely correspond to some large storm surges that are missing in the surge index record. We have therefore made a sensitivity test where we set the surge index at the “gap-start” dates manually to have the same magnitude as Hurricane Katrina 2005. Our results are robust to this test.

    Katrina is #5 on the hit parade. I’d like to know if any “Katrina-like” storms made it through the gap and how we missed them in the historical record. It seems to be a lot of trouble if all they got was a zero.

  38. Charlie says:

    Is there any significance in the fact that Kerry Emanuel edited the PNAS paper?

  39. dp says:

    Since this “increase” is dependent upon “recent” increased temperatures and given I have read on this very blog in the last 72 hours that there has been no warming for more than a decade, this report is garbage. People have to quit blaming temperature rise, or show the temperature has risen and by how much, and why a temperature rise would cause the effect they’re blathering on about.

    If I seem impatient and irritable it is because there has been no temperature rise and it is cold and wet here in Puget Sound.

  40. Gary Pearse says:

    What troubles me is my 60 year “forecasts”. In the 50s-60s there was a peak of Hurricane activity when we were entering a cool down. Now, approaching 60 years later I forecast that we will see an uptick in hurricanes with cooling. The CAGW crowd will be crowing about this being due to warming or CO2. We should be broadening the argument about Tropical Storms or sceptics will be caught off guard concentrating on how it has declined over the decades. How about an expert in the field making a prediction of increases not tied to CAGW or CO2. Hey the warming fellows do this all the time.

  41. James Sexton says:

    Sorry, I haven’t read all of the comments, but, am I the only one concerned about papers going back that far in time regarding hurricane activity? I think it opens many more trap doors than it sheds light on historical information. It’s simply too speculative. If it becomes acceptable to make statements about what happened 200 years ago, then it opens the door to fallacious certitude.

    Consider how many people uncritically accept statements about global temps over 100 years ago. It’s a lie that anyone can know what they were. I would regard any proclamations about hurricanes 200 year ago in the same view. One way or the other, they simply are not credible.

  42. atheok says:

    I forgot to mention this in my earlier post, but Stephen Rasey’s review of the data torture used in the first paper reminded me about some “high tide” issues in the Gulf of Mexico.

    I grew up fishing the East coast and was taught that tides cycle twice daily. That is, two low tides, two high tides on six hour intervals. Then I moved to the Gulf, New Orleans to be exact, but I fished all along the coast, including near that Pensacola tidal station. Yeah, I used to live in that area Katrina flooded when the dike slid sideways. By the way, that area was filled in bayous/swamp and was above seal level when houses were built there.

    Anyway, the tidal frequency in the gulf is NOT the same as most places! Tides in the Gulf of Mexico operate on a different frequency and there generally is only one high/low tide each day.
    http://tidesandcurrents.noaa.gov/gmap3/ (Click on Florida and then the Pensacola tidal station).

    While there in lovely NOAA lala land website, I was curious about some links. Interesting seal level link here. http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml. Makes me wonder if there is someone who doesn’t have jimmy the thug’s thumb on him. I also wonder just how this employee is ‘measuring’ sea level…

  43. atheok says:

    errata
    seal… right!
    sea sea sea,
    must be that third thumb of mine typing by itself.

  44. day by day says:

    dp says:
    Since this “increase” is dependent upon “recent” increased temperatures and given I have read on this very blog in the last 72 hours that there has been no warming for more than a decade, this report is garbage.
    **************************
    Boy do I agree with you!

  45. P. Solar says:

    John says:
    >>
    Whether there has been an actual increase in tropical cyclones (TCs), or whether there has merely been an increase in our ability to detect them, is a subject that Chris Landsea of NOAA has been researching steadily over the years.

    Here is a link to his 2010 paper on the subject, in which he and his co-authors suggest that the detected increase in TCs is most likely due to better detection techniques:

    http://www.aoml.noaa.gov/hrd/Landsea/landsea-et-al-jclim2010.pdf
    >>

    I have a lot of respect for Landsea’s loud rejection of IPCC and his highlighting the corruption of due process in their dismissal of expert recommendations that did not fit their political agenda.

    There may be a valid point in detection techniques introducing some bias, however, looking at the accumulated cyclone energy and non-detrended AMO (N. Altantic SST) the correlation looks pretty strong to me.

    [Note there is a step adjustment of SST data in 1925 here. This step in SST needs looking into, but it not really relevant to this discussion]

  46. P. Solar says:

    Here’s the graph ACE vs AMO : http://i49.tinypic.com/xbfqtw.png

  47. Alex Heyworth says:

    I can’t resist saying that this whole debate is a storm in a teacup.

  48. Aidan Donnelly says:

    I have just received and begun reading (again) Shelby Foote’s excellent narratve of the American Civil War (highly recommended), and the last thing I read before I read this post was regarding the expedition lead by Grl Burnside which took Roanoake Island. On the way from Nr Washington to the Albemarle sound they hit a bad storm. Source online: http://www.nps.gov/fora/historyculture/battleofroanokeisland.htm
    Given the time of year (early Feb) it was very unlikely this was a Tropical storm, but I expect it and many other storms would show in the tidal gauge – without knowing the history how would you differentiate that from a TC?
    I think the ‘observation’ they made would have been much better had they _read the newspapers/local histories to avoid false positives.
    As for the other paper – well when it said Computer Models I stopped, I have been in the IT biz since Doughnut memory arrays. They haven’t changed or got smarter..still rely on bits being on or off, the rest depends on what you feed them….

  49. Galane says:

    Compare the historical record to the latter-day record, using only storms that would be known about using historical methods, which would mainly be ones that made landfall or crossed major shipping routes.

    In other words, if a storm was only found by satellite or in the pre-satellite years by airplane, it cannot be compared to the pre-flight historical storm record. If a latter-day storm actually was encountered by a ship on a normal (not weather research looking for storms) route, then include it, same as any storm in the pre-flight era encountered by a ship.

    Now make some graphs showing pre-flight storms and later storms detected or detectable using only pre-flight methods.

    Then *think*, how many storms may there have been before the advent of going looking for them with aircraft and satellites – that *nobody knew about*?

    If a tropical cyclone brews up and nobody sees it…

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