Global Warming is to Blame

Here is the worldwide proportion of hurricanes at Category 4-5 on the Saffir-Simpson Scale. If this isn't enough for you, check below the fold.

Technorati Tags: , , , , , ,

Many hurricane experts seem to downplay the global warming link. For example NOAA says in their FAQ that even in a 2x CO2 world:

  • Preliminary analyses hint that only small to no change in the NUMBER of tropical cyclones may occur, and that regionally there may be areas that have small increases or small decreases in frequency.
  • The PEAK INTENSITY of tropical cyclones may increase by 5-10% in wind speeds, but this may be an overestimate because of simplifications in the calculations.
  • Little is known as to how the AVERAGE INTENSITY or SIZE of tropical cyclones may change due to global warming.
  • Overall, these suggested changes are quite small compared to the observed large natural variability of hurricanes, typhoons and tropical cyclones. However, more study is needed to better understand the complex interaction between these storms and the tropical atmosphere/ocean.

  • Still, the events of the last two years seem so off the scale of previous experience that I wanted to delve further.

    Happily for my work and sleep, the analysis I had thought to do has already been done. Of course, there has been a lot of discussion of the Emanuel paper which says

    Theory and modelling predict that hurricane intensity should increase with increasing global mean temperatures, but work on the detection of trends in hurricane activity has focused mostly on their frequency and shows no trend. Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and -- taking into account an increasing coastal population -- a substantial increase in hurricane-related losses in the twenty-
    first century.

    However, I actually found the analysis by Weaver et al simpler and even more persuasive. Weaver looks at a number of things including the number of storm days (no real trend) and the number of storms (no real trend). But he does what I wanted to do which is ask: "Are there more category four and five hurricanes now?" Yes, by a mile. The proportion of hurricanes which are category four or above has increased from about 16% in 1970-74, to around 36% in 2000-2004. It's doubled! The trend is really clear in his Figure 4 which I reproduce above the fold. Also, the absolute number of Cat 4/5 storms has doubled over the same period.

    Not only that, but the trend is there in every one of six hurricane basins. Here's the data comparing the 1975-1989 period with the 1990-2004 period.

    (Note that this ignores the South Atlantic, which got it's first ever hurricane last year). Steven Stoft has done a statistical analysis of this data, and shows that if the hurricane basins were behaving independently, the odds that all of them would have increased like this were less than 1 in 1000.

    It's not that there are more hurricanes. It's not that there are more hurricane days. It's that more of the hurricanes are category 4 and 5. Everywhere. So either,

    1. Global warming is leading to an increase in the most intense hurricanes (in addition to melting all the glaciers and the North pole),
    2. An unknown global factor is leading to more devastating hurricanes everywhere.
    Occam's Razor says:
    One should not increase, beyond what is necessary, the number of entities required to explain anything
    That says hypothesis 1) should be the world's working hypothesis until disproven.

    Not only that, I think we can stop all the pussyfooting in the press about how no individual storm can be attributed to global warming. Ok, we can't attribute Katrina to global warming. Ok, we can't attribute Rita to global warming. But I think there's a pretty decent argument to be made that two category five hurricanes in the Gulf of Mexico, back-to-back, inside a month, is not something that would have happened if global warming had not doubled the incidence of category 4 and 5 storms.

    Given that global warming appears to be causing probably irreversible runaway changes like melting the permafrost, I think the only question now is how long it is before we need to add a Category 6 to the scale.

    Welcome to the twenty-first century.

    Will ongoing, repeated impacts on the oil infrastructure be the thing that finally convinces the Bush administration that Global Warming is real, and therfore lead to a real response?  There would be some sad irony in that.


    Yeah.  It's definitely hitting those guys in a place they understand.  I somehow don't think they were too bothered about the Inuit seal hunt or the polar bears.
    BTW - are you out of harm's way?
    Me?  Yes, I'm an ocean away...  Atheistically praying quietly for those who aren't in a helpless, hopeless, hopeful way.


    I think jaymax is a different J than the one you're thinking of. That J has told me that he's OK...probably...
    It's a good thing that we're not going to hurt our economy reducing greenhouse gas emissions.

    Humour aside, even the oil industry has to wake up soon and realise that their insurers are going to nail them to the wall for rig insurance in future. Maybe that will motivate their muppet in the White House to start taking the problem seriously...

    I posted this on the Rita comment thread 1:

    Over here in Europe, the scientists and the media explain it very good. We ARE entering a natural high activity hurricane cycle, but climate change IS responsible for every other tropical storm becoming a huge cat 5 monster. Would all of this have been even an issue, if Katrina had been a cat2, and Rita a cat1?

    As a European, I am amazed at the media attitude in the USA. They have really developed a consensus where no mention of the words "climate", "change" and "warming" is allowed in any combinatioin. Not on the TV, newspaper, nor even in the Internet.

    That is incredible and coupled with the newly reinvigorated attacks on science on behalf of the christian fundamentalists's "Intelligent design" against evolution teaching in the schools, it is very, very sad (and very dangerous also).

    So, if you want information about climate change, you must look farther away than the USA and you'll see there is little or no controversy on the majority of things.


    indeed Mike.  that is why most informed Americans (which there are few) don't look to mainstream TV or radio for their information.  it makes it more difficult, but you gotta know you're being fed propaganda if all u do is watch/read corporately controlled media coverage.  
    To be fair, its not so much that people need to look away from the US for information, its more that they need to look away from the mass media.

    RealClimate is a US site for example, and you can't get much better information about global warming than you do there...

    Well, I didn't exactly say "to look for information", but to "see that there really is no controversy". Even if you are well informed, from inside the US it would seem there is a big argument going on between the proponents and detractors.
    in israeli american media circles (which is to say, most of the american mainstream), it's common knowledge that global warming, sea level rise and peak oil are all antisemitic plots designed to show that israel and israeli americans had a motive to stage 9/11 and the ensuing wars in the middle east. all those theories are based on bad science foisted upon an unsuspecting and gullible american by neofascists and tree huggers.

    of course, the deathwish christians of pat robertson's ilk have had a motive to expel palestinian arabs from jerusalem since the 1830s, when a young scotswoman had a vision of christians being raptured out of their socks once the temple is rebuilt on the temple mount, which is now the site of the al aqsa mosque, which sharon visited with a small army in september of 2000, which kicked off the current intifada, which coincided with PNAC's call for a "new pearl harbor".

    i wish i was making this up.

    i won't mention cheney's 1999 speech about peak oil at the london institute of petroleum, cheney's may 2000 call for the construction of 1300 to 1900 new power plants ---mostly nuke no doubt--- or his energy policy development group's emphasis (june 2001) on nukes and hydrogen.

    i wont mention those things because that would lead to speculation that 9/11 was staged to provide the pretext for the middle east/central asian wars now in progress, which are necessary, as per PNAC, to control china's access to energy before it becomes a rival militarily to the usa.

    and i won't mention those things since that might lead to speculation that these wars are also needed to capture enough oil to sell at high enough prices to finance the conversion to hydrogen.

    all three factions mentioned above ---the likudnik israeli americans, the deathwish christians, and the corporate fascists like cheney--- are represented in the makeup of PNAC, and PNAC more-or-less called for "a new pearl harbor" to kickstart the wars in september of 2000.

    don't shoot me, I'm only the piano player

    Good post! I admire your restraint and discretion in not mentioning those items. You have inspired me to not mention white nationalism, and to refrain from any broaching of the forbidden topic of ecofascism. Additionally, I would like to encourage everyone to not think about how unfolding events call desperately for a synthesis of the two. Shhhh!
    "... and peak oil are all antisemitic plots..."

    Remarkable.  Several months ago I heard the view that peak oil was actually a zionist plot.  (I seem to remember that a conspiracy theory guy called that to ASPO's Campbell.)  And more recently I heard that the PO theory was under cover being propagated by big oil companies to justify higher prices.

    Can we conclude then that peak oilers are doomed to be hunted down and killed, no matter by whom?

    read perle's 1996 paper for netanyahu "a clean break", that calls for the occupation of iraq.

    perle was instrumental in the founding of PNAC, which in a paper "rebuilding america's defenses", published on PNAC's website in september 2000, called for "a new pearl harbor" to motivate americans to support the wars now in progress.

    PNAC counts among its signatories the usual israeli americans prominent in the bunnypants administration, in addition to deathwish christians and corporated fascists, most prominent of which is dick cheney.

    i should have added that the document that called for "a new pearl harbor", PNACs "rebuilding america's defenses", was adopted by the bunnypants administration in september of 2002 as its official National Security Strategy.

    in some cases, the documents' wording is identical.

    the urgency in getting these wars in the middle east off the ground is caused, of course, by peak oil. high ground for israel, control of all that oil ---which, according to PNAC, will deprive china of the oil necessary to industrialize into a military rival of the usa--- all this has to be accomplished before israeli american armies run out of gas because of peak oil.
    Another irony is that the damage wrought by Katrina and Rita will be used to justify expanded drilling and production in (of all places) Florida and the Gulf of Mexico -- which is self-defeating on so many different levels, it's hard to get your mind around it.
    One thing I wonder about:

    This analysis and the data associated with it is extremely compelling...but it is a very short-windowed view, as it only goes bac 35 years.

    I would like to see a couple of similar analyses:

    1. Same 5-year time-frame, but going back to 1900 or 1850 - recognizing of course that the data will be much more sparse, and perhaps not available in all places.

    2. Same data, but on a yearly, rather than 5-yearly basis, just to see the degree of variability.
    You've hit the nail on the head.

    Global warming IS occurring and IS raising sea surface temperatures (which in turn drive hurricane formation).  However, climatological models still indicate that most of current upswing is part of the normal multi-decadal hurricane cycle (an approximately 40 year cycle).

    For an analysis like this to be useful it MUST SPAN MULTIPLE CYCLES.  This analysis only shows that the high part of the cycle is more active than the low part -- which is what a cycle is all about!

    Note that I am NOT saying that global warming is not an important issue because IT IS.  However, the signal to noise ratio in such a limited slice of data still makes it scientifically difficult to separate the effects of global warming from those of the normal 40-year cycle.  We need several more years of data at least (normalized for the effects of the cycle) before we can conclude that global warming is causing an increase in average hurricane intensity.

    No!  The multi-decadal cycle is a North Atlantic phenomenon - and yes it's definitely part of what's going on in the US.  However, Weaver et al's analysis is global - so one has to posit some global cycle of unknown mechanism to explain this, which Occam would tell you was a bad idea.

    The reason his analysis doesn't go back further is because of the limit of when we have satellite data.  Before then, the data might have biasses.


    You are absolutely correct and I posted a few days ago about what has been known and modelled in the SCIENTIFIC community for 2 decades.  Recent data is CONFIRMING/SUPPORTING hypotheses and models.  The scientific community is in general agreement and becoming more confident every day about ramifications of Global Warming.

    The point is that most of the populace are not scientists.  Any anomolous data not fitting the models is ALWAYS brought in to the argument.  These are used by non scientists to try and discredit scientific consensus.  As a practicing scientist I fight this use of scientific data in non scientific ways on a daily basis.

    Scientists by training must remain open to different view points.  Idealogs are not constrained by this view point and will hold to beliefs in the face of mounting data sets.  It is a "I know the truth don't confuse me with the facts" problem.  The problem in the U.S. right now is we have to much power in the hands of the believers and not enough in the hands of the pragmatists.

    More data from scientists is not going to change the equation until the balance of power changes.  This is true for Global Warming, Peak Oil, Habitat/Watershed Distruction, or any other scientic based concern area for human survival.  

    There is a good discussion about hurricanes and GLOBAL WARMING at RealClimate site. Go to

    There is an answer to your question there. Look at post # 199

    "We've only had satellite data since the late 1960s-early 1970s. Before that, back to approximately the end of WWII, the U.S. had airplanes doing measurements for North Atlantic hurricanes.
    But I don't understand how sea-based measurements could exist back to 1851, because I can't believe anyone could or would sail a ship into the eye of a hurricane, to measure the point of lowest pressure:"

    The data you want NOT exist. There is data only for after the Second World War. The data that exist show CLEARLY that GLOBAL WARMING is causing more strong hurricanes. There is a strong correlation between ocean temperatures and hurricanes strenght.

    Don't dismiss the data we have because you want a data that IT IS IMPOSSIBLE TO HAVE. That behavior is not scientific.

    Any rational human will see that there is Global Warming. Evidently rationality is not possible at USA, because only at USA there are sycophants questioning Global Warming.

    João Carlos

    Sorry the bad english, my native language is portuguese.

    I am proud to live at Brazil... and yes, we had our first hurricane last year, 59 people died and we thank to USA and Bush for that.

    It is unfair to thank the americans and not give us Europeans our fair share! We are not far behind at 17% to 25% of world emmisions (sure the Japanese would want some mention too!)

    No, but point taken. Americans watered Kyoto down, and then Bush droped it. They couldn't have done more against international efforts.

    I suppose you also blame Bush for the fact that MARS is also CURRENTLY experiencing global warming.  If you liberals would learn to keep an open mind, we would all be better off.  I suggest you read "State of Fear," by Michael Crichton.
    from a review of crichton's opus... "It's ironic that in excoriating scientists and the public for insufficient analytical skepticism, Crichton has produced a book that demands a sponge-like passivity on the part of those reading it."

    more reviews of crichton's book here

    and so what if mars is warming? and so what if earth's global warming is not man-caused, despite tons of documentation that it is man-caused? warming is warming.

    the big problem with global warming is, even if we are in a cyclical warming period, what about overshoot as a result of an accumulation of man-caused heating agents?

    and to bring home israeli concerns about capturing high ground before israeli american armies run out of gas, substitute "haifa" for "new orleans" in the last couple weeks headlines.

    you are encouraged to read up on clathrates.

    you can't create data where it doesn't exist. That is bad science. We can make assumptions. One is that category 5 hurricanes have always existed. The data do not support global warming is the reason why there is an increase in hurricane activity.
    Variability is a canard.  It cannot explain the observed changes in the energy balance of the troposphere and oceans.  There isn't any nonlinear advective mechanism for increasing the global temperature of the troposphere and the surface layers of the oceans.  The only mechanism is changes in the radiative transfer associated with carbon dioxide and methane. Without the seeding effect of CO2 you would not get secular water vapor accumulation in the troposphere.  Unlike CO2, water gets recycled back to the surface on a relatively short timescale (i.e. much less than a decade).  So to increase the relative humidity of the troposphere you need something else to increase the temperature (including that of the oceans).

    Of course once the relative humidity increases it re-inforces the warming trend.  In turn, the higher temperatures begin to release methane from permafrost reservoirs and possibly clathrates.

    Here ya go:

    Data all the way back to the 1850s.  There's no doubt that simply comparing the last decade to the period from 1970 to 1995 is not a totally fair comparision because of the effects of the multi-decadal variability in the Atlantic oscillation.

    In the 30 years from 1930 to 1960 there were 26 major hurricanes (i.e. Cat. 3-5).  From 1970 to 2000 there were only 14 so you can see that we are definitely in what can be termed a "natural" or historically precedented upswing.

    That said, the previous "busy" decades only saw one Cat. 5 landfall (though there have been 2 more since then).  Remember Katrina was only a Cat. 4 at landfall and Rita will likely be the same.

    I am personally a firm believer that we are already seeing the effects of global warming in many parts of the world (see my previous post at the bottom of this thread  But, I still think it is a bit early to say the uptick in intense hurricanes right now is directly correlated to global warming.  If this trend pans out for another decade or two, then I'd be pretty convinced.

    Exactly my point.  I've seen data indicating that we may very well be in a natural upswing in more intense hurricanes.  I tend to believe the scientists who have produced good arguments on why we should see increased magnitude hurricanes, but the reach that conclusion with the limited data of 1970 on is not science.  It ignores so much that it is largely worthless.

    Hence I said and will continue to say things like "there is good reason to believe" and "may cause" etc etc.  The statement that these strengthened hurricanes "are cause by global warming" is an opinion.

    And Occam be damned.  :-)

    Here's another link of the Atlantic Basin storms that turned into Category 5 including info on the year and whether or not they made landfall anywhere:

    The absence of a reliable long time series for hurricane strength at sea will be a problem for doubters.  However, a link between climate change and individual temperature events has been drawn pretty conclusively here for the human contribution to the European heat wave of 2003, where the temperature time series goes back to 1851.  It's pretty argumentative to believe that something similar is not behind Webster's trends.    
    This analysis bugs me.  What I see: (1) Two options, one called "simple" and the other "unknown"; (2) Occam's razor, which doesn't define "necessary," and is not a principle of science in my mind--scientific truth equals predictive and explanatory capability; (3) a global phenomenon is considered over an incredibly small time window--where is the data for hurricanes over the last 10000 years?  (4) A firm conclusion.

    Theoretical models lead one to believe that global warming will increase the strength of hurricanes. So theoretically we would expect it, though one can tweak the models to come up with conflicting results.  And I suspect we don't know the relationship between global warming and strength. How much stronger, in other words.  Then, we have evidence of stronger hurricanes over a small geological time window.

    It makes one suspicious.  It's not a proof.  It's reasoning on a par with what many here often ascribe negatively to economists.

    In conclusion, there are theoretical arguments that humans made Katrina and Rita stronger--that's what we're saying here--but the data is so sparse as to make it impossible to do little more than state one's opinions and prejudices. What the press should be saying is that the increased strength may be attributed to global warming.  And if you google "katrina" and "rita" and "global warming" that's exactly what the press is saying.  It is true that the press is often poorly representing issues by bringing a pros/cons approach, when there may be 10000 prestigious scientists pro an idea and 2 bozos from unaccredited universities on the con side.

    There are some hard code ideologues arguing that global warming and strengthened hurricanes have no relationship.  And these ideologues inhabit the American govt. But the popular press, in this case, can do little more than state the truth:  "global warming may be the cause of these increased hurricanes." Nothing more.  There is no proof.  And it's not good science or good journalism to say otherwise.

    In the US, the media don't say  "global warming may be the cause of these increased hurricanes."

    THAT is the problem. (and you probably meant, "...the cause of hurricanes becoming so strong, so often..")

    Mike:  I did mean increased strength.

    Economist has a summary of the Webster work.

    Economist has for years taken a very reasoned approached to global warming, maligning the US position, taking global warming seriously.  This is there take, and I think it's exactly the message that should be made: we need to take this serious folks.

    Don't forget methane and CFCs. By the way, the uranium enrichment process of the nuclear industry is responsible for over 90% of yearly CFC emissions in the US (apart from needing two 1000 MW power plants just to do that).
     CFC, apart from being illegal to produce and being the couse the Ozone hole still doesn't recede, is a greenhouse gas 10.000 times more powerful than CO2.
    Stuart, this all makes sense to me. Just a question: have you correlated avearage hurricane intensity as measured by minimum millibars barometric pressure in the eye over time? Or millibars vs. concentration of methane, CO2 or other greenhouse gas in regresion analysis?
        Anyone who is concerned about the possibility of global warming occurring should read the papers given at a conference held in Parliament House, Canberra - see The paper by McKitrick is particularly interesting since it shows the tremendous weight that the IPCC gave to work by Michael Mann and his colleagues.
       Analysis of Mann's work by others has revealed numerous flaws, which have been published in the scientific literature. These criticisms have greatly weakened the scientific case for "Global Warmimg."
        As a consequence of Mann's refusal to supply his data and programs to his critics, Congressman Joe Barton, who chairs the House Energy and Commerce Committee, has asked Mann and his co-authors to respond to various questions.            
        More information on this is available at
    According to the George Marshall Institute (GMI) website, to which McIntyre is affiliated, he "has worked in mineral exploration for 30 years, much of that time as an officer or director of several public mineral exploration companies. He has also been a policy analyst at both the governments of Ontario and of Canada." GMI, meanwhile, is a well-known conservative think tank., a personal web blog of McIntyre, is hardly an authorative source on climate issues.

    The letters of Barton to Mann, Bradley and Hughes have been critisized by numerous notable individuals and organizations. See

    The misconception of IPCC conclusions being based on Mann is advocated by McIntyre to make his attacks on Mann's work look more influential. In reality Mann's work is a minor (and rather good) piece of a large body of scientific work.

       Meltwater, I doubt that your statement "George Marshall is a well known conservative think tank" is here or there regarding McIntyre and McKitrick's studies of "global warming."
       There's a pretty good discussion of the issues at If you are sceptical about McIntyre's work, why don't you read that blog? If you see flaws, tell him. His and McKitrick's recent paper in Geophysical Research Letter's debunking Mann's work is described by the American Geophysical Union as being one of their 10 best recent papers.
       If you think Mann's work is minor, why was it so heavily promoted by the IPCC?  See McKitrick's article that I referred to in my previous post - this details how heavily publicised Mann's work was.  The IPCC wanted something flashy  which is why they took the extreme position of publicising the hockey stick and completely ignored the tropospheric data obtained by satellites. Their report is a con job.
        The basic problem for Mann is that there are flaws in the paper on the Hockey Stick and these flaws have been found by McIntyre and McKitrick. This is confirmed by Mann refusing to give McIntyre details of his computer programs and data until forced to do so by Congressman Barton. A real scientist, without something to hide, would have supplied them when asked.  
       It's also very peculiar that Mann has stated that getting more proxy data would require expensive and lengthy trips to distant places carrying a lot of equipment. None of these are true - one site is at Bishop, CA, the data could be obtained in a short period of time and the basic equipment looks about the size and cost of an apple corer!  
    Dear "astronomer1",

    M&M have done no credible studies on global warming. They have appeared, mostly in non-scientific contexts, as vocal critics of GW, but in fact they have no qualifications as climatologists (McIntyre is a retiree from oil industry, McKitrick an economist). They do not even convince on the methodology part of the discussion - see, e.g.,

    Given clear conficts of interest, lack of qualifications, and the poor quality of their arguments, I find it interesting that you try to present M&M as somehow comparable to work behind IPCC. M&M presents their personal opinions, or opinions of their funders, while IPCC reports summarize the work of a whole scientific community.

    If you actually read the IPCC reports (look for them at, you would find hundreds of references, and a broad introduction to the background of global warmings. Mann's historical temperature reconstructions are a small part of the total evidence. Since the latest IPCC report the reconstructions have independently confirmed by several groups.

    Apart from a handful of oil-industry-funded "sceptics" and few real, credible sceptics, the discussion about the existence of global warming and its causes is over. Only details, like the exact magnitude of future warming, or the impacts of warming on the hurricane intensity (which this thread was all about) are now uncertain.

    BTW, your claims about Mann and colleagues refusing to give data or computer programs to public is simply not true. Barton's harrasment of three climatologists has fired back in a big way.

    Just some background.

    Look at this NCAR page.
    As global warming causes oceans to become warmer, and more moisture is held in the atmosphere, the intensity of hurricanes and the amount of rain they produce will likely increase, according to NCAR scientist Kevin Trenberth and others. There is strong evidence that global warming has been increasing the intensity of hurricanes for over the past few decades.
    The hurricane people (William Gray at CSU, Chris Landsea, others) are basically in a turf war with the climate scientists. When (climate scientist) Trenberth came out publicly and made the connection between global warming and hurricane intensity, Landsea became incensed and resigned from the IPCC. Look at this page from David Appell's science blog Quark Soup. So you will find generally that people who specialize in hurricanes will say that frequency and intensity seen of late is all due to natural variability -- the interaction of multiple natural cycles. The climate scientists point to warmer SSTs and this is, of course, the key to Webster et. al. is
    Tropical ocean SSTs increased by approximately 0.5C between 1970 and 2004 (21). Figure 1 shows the SST trends for the tropical cyclone season in each ocean basin. If the Kendall trend analysis is used, trends in each of the ocean basins are significantly different from zero at the 95% confidence level or higher, except for the southwest Pacific Ocean.
    The world's oceans have been warming for about 45 years now and this warming is consistent with climate model results. However, there is evidence that the world's ocean temperatures are also subject to natural variability, so there is some noise in the data (e.g. this study on the Pacific). The classic study at present is Warming of the World Ocean by Levitus, et. al. (Science 2000) that shows "The global volume mean temperature increase for the 0- to 300-meter layer was 0.31C, corresponding to an increase in heat content for this layer of ~10 to the 23 joules between the mid-1950s and mid-1990s. The Atlantic and Pacific Oceans have undergone a net warming since the 1950s and the Indian Ocean has warmed since the mid-1960s, although the warming is not monotonic."

    Generally speaking, the Earth is out of radiative heat balance - due to greenhouse gases (GHGs), more heat is being absorbed than is lost. That extra heat has to go somewhere because the system must come into balance. The extra heat melts ice and is absorbed by the oceans. So SSTs are up and hurricanes are apparently more intense as a result. The Earth will come into radiative heat balance eventually if we quit emitting GHGs but at a higher global mean surface temperature than before the Industrial Era. Of course, this balance will take hundreds (if not thousands) of years to acheive.
    Unlike the PR and politics based faux dispute about global warming; it is my my impression that there is an meaningful scientific debate about the existence of a valid linkage between global warming and hurricanes.  "The hurricane people (William Gray at CSU, Chris Landsea, others) are basically in a turf war with the climate scientists." is a colorful way to put that, I guess.  I trust these folks to puzzle out over time what the nature of any linkage between the two is.  Meanwhile it certainly appears to me that the hurricane people have a surprisingly good handle on the seasonal patterns.

    That first chart is very misleading; it doesn't go back in time far enough.  For example it doesn't show the violent hurricanes of the 1930s thru the 1950s.

    Meanwhile back in the world of PR, politics and it's associated point scoring (e.g. polling data) it seems obvious that the current cycle of increased hurricanes will add lots of point to the global warming is real side of the board.  So maybe, even if the scientists are threatening to demote Pluto's status as a planet, the gods are on the side of truth;

    Weaver et al don't study that because there isn't reliable global data on hurricanes earlier.  There's North American landfall data, but it's a pretty low statistics noisy time series.  What's compelling to me about Weaver's study is the global pattern.  And of course Emmanuel extracts the correlation with SSTs in the NA data by using a much more sophisticated measure - integrating hurricane power over the whole hurricane and track.  There are people working on trying to use tree-ring isotope studies (isotope composition of the air is different during hurricanes) to produce longer hurricane time series.

    I agree, of course (or I wouldn't be relying on Occam's razor) that the case is not proven beyond all doubt.  However in real world decisions, we almost always have to act long before there is no reasonable doubt.  We (the US) have chosen not to act on global warming yet, despite the fact that the evidence for the phenomenon is compelling to anyone who isn't stuck in complete ideological rigidity that it must not exist because it isn't convenient for their ideology (or their short-term self-interest).  The rest of the developed world has chosen to act in a very incremental not-yet-adequate way.

    In respones to TRE - Occams razor actually has a long and venerable history  in science, and captures an important issue: don't use overcomplicated theories because you'll overfit your data.  If you have a bunch of data that lies mostly along a straight line, you're best off extrapolating it with a straight line.  If you fit a ten section piecewise differentiable cubic spline, you'll get a gorgeous fit to the data, and it will go nuts just off the end of that data.  If you add epicycles to your planetary orbits, you can make them work, but it won't help you figure out what epicycles to throw into the next planet's orbit.  In this case, if you fit a global oscillation (of unknown cause) to the top graph, you won't get useful (ie falsifiable) predictions since the data will not constrain a sine wave much, whereas they will constrain a straight line fairly well.

    Finally, I note two issues: The Oil Drum is a blog, not a peer-reviewed journal.  The purpose, and standards, are different.  And on this issue specifically, there exists a large network of conservative organizations and PR companies, well funded by industries with vested interests, who's (very successful) PR strategy is not to prove global warming wrong, but instead to convince everyone there's uncertainty and debate and doubt, and therefore no action should be taken.

    I personally think the evidence for the hurricane/global warming connection is compelling at this point - the balance of the evidence leans strongly to it in my opinion based on the data I've looked at and reading I've done.  I would gladly bet money that there will be more and bigger hurricanes in twenty years than today.  (In contrast, I would not bet, say, as to whether peak oil is before or after 2008 because I don't see the data clearly enough yet).  Now that climate change is killing people in large numbers and causing major property destruction, I'd rather stand up and be counted that this problem needs to be taken extremely seriously by saying what I think clearly, rather than hedging it with contingencies and nuances (however valid some of the latter might be).

    Stuart:  I agree with much of what you say.  This is a blog, not peer reviewed paper (maybe we get to play the peers sometimes!!!!).  I also feel, like you've expressed, that there are good reasons to think that increased hurricane intensity can be attributed to global warming.  But I'm cautious because of the variation data that I've seen over (longer terms, which has been discussed in the comments section).  Finally, I do realize Occam's is a good technique--keep it simple stupid as the bumper sticker says.  And the saying "keep it as simple as possible, but no simpler."  Though I always had a soft spot in my heart for all those complicated models to explain retrograde motion.  My primary point was that we had two possibilities: (a) global warming and (b) don't know.  It's a bit of a stretch to use Occams to say "I've got one answer and therefore it's the simplest by default."  Particularly when the window of time was so small.

    Anyway, keep up the good work.  I'm particularly interested in the modeling on non-conventional, as my belief all along--yeah yeah, I can't prove it--is that non-conventional cannot make up for depletion effects when they set in globally.

    UK leading scientist agrees with Stuart.  "Super-powerful hurricanes now hitting the United States are the "smoking gun" of global warming, one of Britain's leading scientists believes."  Also says that "The increased intensity of these kinds of extreme storms is very likely to be due to global warming."

    Note that they still don't mention the longer term studies.  His use of "very likely" puts me in sync with him.  (link)

    And not trying to flog a dead horse (or is it a dead thread), but Calculated Disk has a summary of the debate on global warming and hurricane strength.  And he raises a point similar to Stuarts, which I must agree with: the time for dithering and hemming and hawing should probably be over. For political reasons if nothing else.  The US, in particular, has gotten itself caught up in a post-modernist relativistic mindset.  Funny enough, it's the fundamentalists who have embraced relativism.  Scientific consensus supports evolution (against creation) and for human caused global warming (against other natural causes or "what global warming").  So the fundamentalist response is "let's keep the jury out on global warming" and "let the children view multiple perspectives, including creation science."  It's a political maneuver on their part, embracing relatvism to ensure that there incorrect opinions are pushed into the public dialog and discourse, in the the media, etc.  Then we have two talking heads on television, one a nobel laureate climate scientist or something like that, and then some dope from Fossil-Fuel-Funded-Tech-University.  And compare and contrast, relativistic post-modernist there-is-no-truth balance is presented to the audience.

    Here's the issue.  Those with the scientific mindset, even those who accepts post-modernist thinking, must ensure we are right with a high degree of probability.  We don't want to be guessing.  Using hunches.  And then, if mistaken, credibility is lost.  But I really don't think credibility can be lost at this point by arguing strongly that Katrina and Rita are likely outcomes of human activity.

    You may be interested to know that global warming, earthquakes, hurricanes, and other natural disasters are a direct effect of the shrinking numbers of Pirates since the 1800s. For your interest, I have included a graph of the approximate number of pirates versus the average global temperature over the last 200 years. As you can see, there is a statistically significant inverse relationship between pirates and global temperature.

    Excerpted from

    How can you count how many pirates there are?  Do they put it on tax returns under occupation?  I've read that we now have more pirates than in the 18th century. They hijack yachtes to use in drug smuggling.
    It could be argued that the switch from burning coal in home furnaces and stoves to using nat gas is the cause of global warming. The stats are there.
    Let me challenge the prevalent view of global warming (GW) in a way only peak oilers can understand.

    Could GW actually be a good consequence (maybe the only good one) of man's using up the Earth's fossil fuels inheritance in just a few centuries?

    I will try to answer that by analysing GW's main objective measure (temperature records) in different time contexts.

    First, if we look at temp records for the last 1000 and 2000 years, there is no question that it's shooting up into unchartered territory.  In this context, things look pretty scary.
    (In both charts above, time runs from left to right.)

    Then, if we take a somewhat larger view at the last 12,000 years (the "Holocene"), 2004 still appears warmer than any other time in the long-term average, but now the magnitude of the increase in the last 150 years is not so out of order with that of previous changes, particularly that which took place up to 10,000 years BP (Before Present), when the Earth was coming out of the last ice age.  Moreover, note that the trend from 8,000 BP to the Little Ice Age (XVII century) was slightly downward.

    (In all charts below, time runs from right to left.)

    Finally, if we have a look at the last 450,000 years...

    ... we see that GW might actually be averting the next glaciation cycle that otherwise would be due to set in not too far in the future. (I.e. in a few thousand years.)

    Another broadly used parameter to assess GW is CO2 concentration.  The next chart, focusing on measurements at the Vostok Antarctic station, shows that it is definitely correlated with temperature.

    Though that says nothing about the specific causal relationship, just knowing that dropping CO2 levels is a feature of glaciations seems enough to start taking a hard look at all the issue of emissions and the Kyoto protocol.

    Because, if we assume that in 100 years there will be negligible quantities of oil and natural gas left, and in 200 years there will be no coal left either, then from 2200 at the latest the only fuel people will have to keep themselves warm will be wood (and dung, but let's stick to wood for a clean discussion).  If on top of that they would face the prospect of a new ice age, that would make a case for a much more severe population reduction than any of us would want to think about.

    In case someone argues that man has already managed to successfully go thru ice ages so we should not worry about that, I admit that, if we restrict the definition of man to Homo Sapiens, which probably appeared 170 - 250,000 years BP, man has already been thru at least 2 ice ages (according to )
    where only the last ice age caught him out of Africa and thence meant enduring really hard cold.  However, the human population in e.g. Europe up to 12,000 years BP was way smaller than today's, so man's past performance does not nearly indicate the magnitude of population reduction that would need to take place in order to sustainably keep people warm out of wood and not going the Easter Island way.  (Alternatively, Europe could be depopulated by massive migration to warmer places.  Figure African countries cracking down on European immigrants?  Or Mexico deporting Americans back north?)

    So, GW might be the only good thing left to the people of more than a few centuries into the future by "those bastards of the XIX, XX and XXI centuries that burnt all the oil, gas and coal".

    yep, good thinkin'. turn the planet into a desert now, while we have the chance, to save our descendants the embarrassment of having to move back to africa.
    Dear meltwater,
                    How on earth can you say that McIntyre and McKitrick has published no credible studies on global warming? They have published a paper in Geophysical Research Letters, which is a major research journal for this topic. In addition, their paper was selected as one of 10 Journal Highlights!
        This paper shows that Mann et al's  work will produce a hockey stick from random data, no less! From random data! Do you expect people to believe Mann's work after that?
        I note also that Mann's estimates of the earth's temperature do not show the Medieval Warm Period or the Little Ice Age - did the Vikings not live on Greenland and did the Thames not freeze in England?
         Mann did not react in a professional way to the problems which M&M found in his work. He refused to supply them with his data and programs. In addition, he and his collaborators have not archived their data, which is something that many journals require. Unfortunately this seems to be a common trait in "climate science".
        I'm also very doubtful about global climate models. Some years ago I asked Jonanthan Tennyson to calculate some data, wavelengths, transition probabilities etc for water vapor for me. (Jonathan's group  is probably the best in the world for doing this.) He has told me that the water vapor data currently available is incomplete, and so climate models include ad hoc methods (fudge factors, in other words) to try to include all the water vapor absorption in the Earth's atmosphere. About 20 W m**-2 of absorption can't be properly included, a big factor since the average amount of sunlight incident upon the earth is 326 W m**-2.
        If you wish to read the views of other sceptics - see
    the vikings died out in greenland because they displayed the exact same type of cultural bullheadedness you are displaying.

    CO2 rising

    potential clathrate disaster

    glaciers retreating

    pack ice thinning

    antarctic ice sheets collapsing

    potential sea level rise ---80 meters in new orleans and haifa and maybe even miami

    Stuart read the Webster et. al. paper, Emanuel's paper and some other sources on the subject of climate change and hurricanes -- his post on this subject was excellent and fair.

    I tend to think of TOD readers as cutting edge, state of the art people, but then I see the usual references to "McIntyre and McKitrick" and other nonsense here -- I've seen this also on Real Climate as well where -- to put it bluntly -- random internet idiots get the unique opportunity to interact with world-class climate scientists like Gavin Schmidt of NASA GISS or Michael Mann (now at Penn State).

    Sometimes I forget that here at TOD, thinking of a random sampling of internet bloggers, we're obviously bound to get a large number of people who have no fucking idea what they are talking about.
    Could you possibly use less data to come to the conclusion that so called global warming is causing category 4 and 5 hurricanes to appear by the dozens? You use 1970 as your benchmark year on the graph and yet Noaa points out that it was in 1970 that we actually began a down cycle that lasted through 1994. So in fact one can argue that  what we are seeing since 1995 is a return to a high cyclical period (or perhaps even a normal period) in Atlantic Hurricane activity which by the way also occured between 1940 to the late 1960s.

    Also bear in mind that when dealing with number of storms per year and their peak intensities remember that there was a time where reconissance flights and satellites did not exist. So unless a ship happened to be nearby not only could a hurricane's peak intensity not be known...its quite possible that a storm could exist undetected offshore.

    And while activity in the atlantic has been has co-incided with decrease activity in the tropical eastern pacific. Or is that global warming as well?

    As a meteorologist i am getting increasingly disgusted with data being used to justify political outcomes. Perhaps it is global warming thats doing all this. But so far the data ain't showin it!!!

    And btw i love your blog and have a link on my blog...  I follow companies that move oil and gas around.


    You ignored most of what was said in the post, papers, and discussion. The increase in percentage cat 4/5 is global. It is in every hurricane area, not just the North Atlantic. The reason the analysis is only since 1970 is because that's how far back the satellite data go - I agree about potential biasses with older data. So what's your explanation for why the percentage of Cat 4/5 storms is increasing throughout the entire globe?