NOAA: Hurricane forecasts

Guest commentary from Thomas Crowley

NOAA has issued its annual forecast for the hurricane season, along with its now-standard explanation that there is a natural cycle of multidecadal (40-60 year) length in the North Atlantic circulation (often referred to as the “Atlantic Multidecadal Oscillation”–see Figure), that is varying the frequency of Atlantic tropical cyclones, and that the present high level of activity is due to a concurrent positive peak in this oscillation.

AMO Pattern

There was not one mention of the possibility of global warming being a partial factor for these changes (see also this NY Times report on two recent studies).

trop. temperature - Anthes et al (2006) The average reader of newspaper articles on this prediction might well have concluded that there are in fact two camps on this subject – one global warming, one natural variability. But I think there is a one-way commingling of the camps. I suspect that most people leaning toward global warming as a contributor to the unusual increase in the magnitude of Atlantic tropical storms and hurricanes would readily concede the possibility that the AMO could, in addition to the El Nino/Southern Oscillation, modulate any greenhouse gas contribution to the enhanced activities of tropical storms.

It is not at all clear to me that the natural variability camp sees any need to commingle with the global warming community.

Is there any way to distinguish as to the relative strengths of arguments of these two camps? Actually, it is quite easy to do so. If the natural variability argument applies there should be little difference in the statistics of the present phase of the AMO with the past. But global temperature data incontrovertibly indicate that there has been a widespread warming since the previous positive phase of the AMO (e.g. 1940-1960). This type of warming cannot be produced by the ocean circulation, which to a first approximation just moves heat around on the planet – what it robs from Peter it gives to Paul.

Furthermore, rigorous statistical studies indicate that the pattern of warming can be attributed to greenhouse gas increase. I have seen no effort to conduct a standard “detection and attribution” approach to the alternate explanation of the AMO. I encourage the AMO proponents to try it; it is somewhat more objective than simple declarative statements that the AMO are responsible for the observed warming.

Update: The two papers referenced in the NY Times article are now available online: Mann and Emanuel (2006) and Sriver and Huber (2006).

168 comments on this post.
  1. Steve Bloom:

    Re #48: Isaac, are you keeping up with all the papers? I think we all like the science, but the nature of the AGW-hurricane “controversy” is such that it’s become hard to separate science from politics. When NOAA uses an unqualified person like Stan Goldenberg (look at his CV if you don’t believe me) to attack people like Kerry Emanuel, Peter Webster, Judy Curry, Tom Knutson, Greg Holland, Kevin Trenberth, etc. as having drawn conclusions based on theology rather than science, there’s something wrong with this picture.

    My interpretation of Tom’s remark about detection and attribution is that what we might term the NOAA-Gray camp has nothing, while the soon-to-be published Emanuel and Mann (2006) closes the circle on the other side. I have yet to see the new paper, BTW, but I think the case was pretty complete without it. This new BAMS review paper here (and note that list of authors!) sums up the present science nicely, plus there’s obviously much new work on the way. Of particular interest is this in-press BAMS paper elaborating on Emanuel’s work; the finding of high-frequency relationships between multiple AGW effects and hurricanes seems to render unlikely Chris Landsea’s expressed view (hope?) that his reanalysis of early hurricane observations will substantially undermine Emanuel (2005) and Webster et al (2005).

    Recall that recent prior discussion on this site included a comment from NOAA’s Methuviel Chelliah that, contrary to last fall’s official NOAA statement, the recent work by him and Bell did *not* constitute any sort of case for AMO (or other natural cycle) causation. After that part of the controversy went public, NOAA had to strike the Bell and Chelliah (2004) reference and substitute a reference to Goldenberg et al (2001). I think it’s fair to characterize this latter paper as merely speculating about natural cycles. Similarly, we saw here that Bill Gray’s attempt to link Atlantic tropical cyclones to the thermohaline circulation was an unpublishable embarrassment. Recent NOAA-Gray camp papers from Klotzbach and Michaels et al purporting to find fault with Emanuel (2005) and Webster et al (2005) have defects that were obvious even to my amateur eyes.

    Summing up, it appears that the scientific case for the AGW-hurricane link is now very strong, and that NOAA’s contrary stance favoring natural cycle causation is based on belief rather than science. Theology, anyone?

  2. S Molnar:

    Re #49: “The media outlet carrying this contrarian is of course not responsible for what he says”. I beg to differ. The management of the radio, television, and newpaper outlets that carry this sort of thing know exactly what they are doing, have a surprisingly small number of owners, and are very much responsible for the content that they purvey. Education is a good thing, but, in the short run, I believe the only effective way to counter this is economic and political action (a topic for another website).

  3. Mark A. York:

    And another attempt at obsfucation by George Will:

    “Minutes after Gore said that “the debate in the science community is over,” he said “there is a debate between the American ice science community and ice scientists elsewhere” about whether the less-than-extremely-remote danger is a rise in sea level of a few inches or 20 feet . And he said scientists “don’t know what is happening” in west Antarctica or Greenland. So when Gore says the scientific debate is “over,” he must mean merely that there is consensus that we are in a period of warming.

    This is not where debate ends but where it begins, given that at any moment in its 4.5 billion years, the planet has been cooling or warming.”

    [Response: What is obvious to everybody but Will and his like is that Gore’s statement means there is a consensus that we are in a period of warming, that it is caused by anthropogenic greenhouse-gas emissions, and that the world will continue to warm considerably if emissions continue at anything like their current level. Where the debate starts, then, is over what the warmer world will really be like and how bad the consequences will be — how much of Greenland and the West Antarctic Ice sheet might go, the distribution of severe drought and heat waves, and the like. –raypierre]

  4. Steve Bloom:

    Re #50: Eli, in addition to the second paper I linked above, which extends Emanuel’s analysis to reflect the various AGW-related variables affecting hurricanes, have a look here and here to see how ocean heat energy is already being tracked and analyzed.

    Re #53 response: Ray, let’s give Will full credit. He understands the difference perfectly, and confusing the larger debate with the debate over the details was a conscious act of obfuscation as Mark correctly noted. This sort of cheap attempt to trick his less-informed readers is very odd coming from a guy who supposedly prides himself on intellectual integrity.

    [Response: Agreed. –raypierre]

  5. Steve Bloom:

    Re #51: I should hasten to clarify that my dissing of the NOAA stance on the hurricane-AGW connection was of the *official* stance. Of course most NOAA scientists know better.

    Re #11 response: Ray, the new Emanuel and Mann paper seems to still be unavailable, at least on the AGU site (which as of late Sunday night still has the June 6th issue of Eos). Do you have another link?

  6. Michael Jankowski:

    Re#43 Leonard, not quite so – see the comment in post #170 on this thread for example

    [Response: This is hardly a fair remark. The part of the referenced comment I deleted was just an inflammatory screed, not a scientific argument of any sort. Moreover, in the referenced comment, I’m not ignoring Bill Gray’s ideas because they come from Bill Gray. In fact I took quite a lot of time reading over his paper, as you’d know if you read the post on Gray’s latest attempt. I’m ignoring Bill Gray’s ideas because I looked at them and they are rubbish. Of course, time is short and if one looks to some source over and over again and finds that the ideas are consistently rubbish, one tends not to be inclined to waste much more time hoeing that row. But I’ve even gone into things on Milloy’s site and given them serious consideration (e.g. the claims in the “greenhouse primer” there regarding what the Earth’s temperature would be in the absence of convection). You’re going for a cheap shot here, but as far as I’m concerned, you’ve just shot yourself in the foot. –raypierre]

  7. Eli Rabett:

    Thanks for the interesting references Steve. To me the pressing issue is whether the ocean heat energy content can be inferred back far enough that we have a useful climatological record. After all, thirty years from now is a bit long to wait before doing anything

  8. Carl Christensen:

    On a related note to the media screwing up the science, here is a Canadian paper “debunking” Gore’s movie with appeals to (what they claim are) the “experts” in climate science (one of whom was a nutjob I met at EGU):

  9. Michael Jankowski:

    Re#56 (raypierre), I think it was perfectly fair remark based on the first line of your response in the link. But I appreciate that you left the post up so that others could judge for themselves and further commenting so as to try and clarify things.

    While posters seem more guilty of it than people such as yourself, an idea in the commentary attached to the names Christy, Milloy, Michaels, Lindzen, McIntyre, etc, is often instantly (and generally vehemently) dismissed because of the name attached to it (sometimes jusifiably so, but that’s not always clear).

  10. Ike Solem:

    According to these pages, NOAA seems to be predicting that 2006 will be a worse hurricane season then 2005, assuming they haven’t changed their prediction methodology:

    NOAA 2006 Atlantic hurricane outlook

    NOAA 2005 Atlantic hurricane outlook

    All the indicators seem to be in place for another massive hurricane season; all the future warming trends, such as weakening trade winds, northwards expansion of the Hadley cell circulaion, warming equatorial ocean currents, increased moisture in the atmosphere, etc. – seem to point towards a greater and greater incidence of hurricanes in coming decades. Blaming all this on a North Atlantic multidecadal oscillation pattern (which must be coupled somehow to ocean circulation), and which is supposed to undergo a “future downswing” is not supportable by any rational stretch of the imagination.

    Regarding #13 above:
    “After study of trends in timing for spring snowmelt floods in the Upper Midwest, and backed up by a NOAA Press Release in February of 2000 that global warming was happening, adding something about climate change seemed like the right thing to do. However, NWS management concluded that mention of global warming was political and unacceptible.”

    I think what the NWS managers really meant was that mention of global warming was “politically unacceptable.” That’s especially true if they wanted to keep their government careers intact.

  11. Ike Solem:

    A quick follow-up:

    The NOAA group has produced a “seasonal climate summary” addressing the 2005 hurricane season; it may be found at NOAA’s pdf archive page. The title is ” The 2005 North Atlantic Hurricane Season A Climate Perspective “.

    The most curious thing about this ‘paper’ is their list of references – limited almost entirely to themselves and to Dr. William Gray! Now, if you read a scientific article where the only references included are to the author’s previous work, you might – maybe- imagine that they have very biased viewpoint. As one might expect, they religiously avoid use of the phrase “global warming”, but they do mention “the multi-decadal signal” over and over again.

  12. Grant:

    I’ve seen enough graphs of SST versus PDI (power dissipation index for tropical cyclones) to know that the link between increased SST and PDI is strong enough to be probable. But I’ve also done enough time series analysis to know that the available data are not sufficient to establish the link beyond doubt.

    What I haven’t seen is the data on which researchers establish the existence of the “multi-decadal oscillation.” I have the impression that actual SST records don’t go beyond a century, perhaps only about 50 years. Establishing the existence of a genuine oscillation with a *multi-decadal* timescale based on only 50 years data is, simply put, just not possible (from a purely statistical sense); it could be suggested, postulated, but by no means *established* by such a short time series. Doing so with only 100 years data, is dicey at best.

    So: what’s the real evidence for the multi-decadal oscillation? Are there reliable temperature proxies that can be used to extend the ocean temperature record in the Atlantic? How far back do the actual time series go? The proxy record?

  13. Michael Jankowski:

    Re#61 Grant,
    Not much detail here, but from NOAA FAQ:

    “…Is the AMO a natural phenomenon, or is it related to global warming?

    Instruments have observed AMO cycles only for the last 150 years, not long enough to conclusively answer this question. However, studies of paleoclimate proxies, such as tree rings and ice cores, have shown that oscillations similar to those observed instrumentally have been occurring for at least the last millennium. This is clearly longer than modern man has been affecting climate, so the AMO is probably a natural climate oscillation. In the 20th century, the climate swings of the AMO have alternately camouflaged and exaggerated the effects of global warming, and made attribution of global warming more difficult to ascertain.”

  14. Roger Hill:

    I think what the NWS managers really meant was that mention of global warming was “politically unacceptable.” That’s especially true if they wanted to keep their government careers intact.

    Comment by Ike Solem â?? 12 Jun 2006 @ 12:17 pm

    Maybe if enough of them stood by the science instead of their position. Many are retiring and geting out in the nick of time, and I suspect like the general’s they will start popping off. NOAA – another arm of Karl Rove’s army. DisGUSTING

  15. Steve Bloom:

    Re #61: Grant, Tom Crowley’s major point was that the natural cycle folks have essentially nothing. It’s time for them to put up or shut up. Regarding the connection of global warming to PDI (or any other TC-related statistic), of course there will always be some uncertainty. Chris Landsea continues to claim that his reanalysis of historical data will undermine the global warming case, but I think there are growing doubts about that. As far as the case for the natural cycle goes, I think there’s still nothing more than Goldenberg et al (2001); i.e., there’s not much of a case.

    The scientific discussion will get a lot more pointed and overlap even more into the political arena if this season is anything like last year’s. Alberto’s precocious behavior may be a harbinger of things to come.

  16. pat neuman:

    re 59. … what the NWS managers really meant was that mention of global warming was “politically unacceptable.” …

    Why was mentioning global warming considered “politically unacceptable” by NWS managers in Feb/March of 2000?

    The director of NOAA warned the public about global warming on national TV in Jan. of 2000 (CBS). At the same time, NWS managers said global warming was too political to talk about at work or with the public.

    It was obvious that Al Gore’s 1995 book on global warming was not recommended reading materials for NWS staff, before or after G.W. Bush took office in 2001. NWS was not following the same chain of command in 2000 as it is now.

  17. Don Baccus:

    re 59: “According to these pages, NOAA seems to be predicting that 2006 will be a worse hurricane season then 2005, assuming they haven’t changed their prediction methodology…”

    From CNN:

    More than 20,000 people along Florida’s Gulf Coast were ordered to clear out Monday as Alberto — the first tropical storm of the new hurricane season — unexpectedly picked up steam and threatened to come ashore as a hurricane.

  18. Carl Christensen:

    What will be interesting to “track” is if we get say 7 out of 10 “record years” of hurricane intensity & frequency, will they keep saying it’s “natural variability” and we just haven’t “peaked” in this cycle yet? Talk about “new theology!” ;-)

    [Response: That’s essentially what they’re already saying. The prediction, if I may paraphrase it, is for another decade of anomalouslly strong hurricane activity due to natural causes. Probably they’ll insist on another ten years after that to admit there’s something wrong with the natural cycle idea. Thus, they manage to put off facing facts for around twenty years, by which time people will start arguing that it’s too late to do anything to reduce emissions, so we might as well just get used to it. –raypierre]

  19. joel Hammer:

    Interesting. Is all. Are all these quotes taken out of context?

    [Response: No, they’re not taken out of context. Almost without exception it’s just well-trodden and already-debunked stuff from the skeptics standard playbook (e.g. the usual lies about water vapor), and quotes from the usual crowd of skeptical talking heads (Max Mayfield, Tim Ball, etc.). This is just the standard smear. I think we scientists on RealClimate, as well as the scientists who weighed in on our discussion of Gore’s movie, as well as essentially everybody I’ve heard from who is active in research in this field agrees that Gore has done a remarkably good job in putting together the scientific argument in a respectable way. Nobody is laughing at Gore, least of all scientists. It’s interesting to see that the Financial Post’s standards of journalism are no better than those of the WSJ editorial page. Not surprising, but always disappointing. I’ll leave it to other readers to comment on the individual points claimed in the article, as it’s all well-trodden material here. –raypierre]

  20. Isaac Held:

    Steve (#51), thanks for the detailed response to my #43.

    The only major problem that I have with Anthes et al is when they downplay the gross quantitative disagreement between the relatively modest strengthening of storms in the modeling study of Knutson and Tuleya and the 70% increase in Emanuel�s analysis of the power dissipation index since the 1970�s. I am not aware of any theories/models that help us understand the magnitude of the latter. At this point in time the argument for these very large response relies entirely on statistical analysis of observations. Hopefully this will change soon. We have all been misled on occasion by correlations that look convincing at first sight. Until we have better support from theory/modeling, and given the extraordinary importance of this subject, it is important to look hard to see if there are effects that complicate the naïve interpretation of these fits.

    The paper by Elsner et al that you also link to is a nice start in this direction. Their statistical fit implies that if you warm the climate uniformly you get a somewhat weaker response in the hurricane index than if you just warm the tropical Atlantic. So if there is a mix of globally uniform warming and internal Atlantic variability going on, the simplest regression of storms versus Atlantic temperatures would inaccurately over-emphasize the uniform component. A very strong response remains, but this is precisely the kind of multivariate analyisis that we need to help clarify things.

    With regard to Grant�s question in #61 with regard to proxy evidence for the AMO, it would be nice to hear from Mike Mann, who knows as much about this as anyone and seems to have changed his view on this subject recently. Mike may be waiting until his paper with Emanuel on this topic is publically available. Here is a reference in the interim:

    [Response: Thanks Isaac, as usual your comments are very much appreciated here. The Mann and Emanuel Eos article is now out, so folks can see what we have to say rather than rely on hearsay. Some who have claimed that I’ve “changed my mind” about the AMO simply haven’t seen our arguments. Our paper, despite the rumours, does not challenge the existence of the AMO. It does challenge the notion that the AMO has played a significant role in long-term tropical Atlantic SST variations. We note that previous model simulations as well as past statistical analyses that take into account the non-linear nature of the trend in attempting to isolate the “AMO” signal, find little support for any substantial modulation of tropical Atlantic SST by the AMO. Most of the AMO SST variability is in the extratropics. After accounting for the fraction of tropical Atlantic SST variability over the Main Development Region (MDR) associated with global SST trends (which account for most of the forced long-term SST variability as it is represented in the global mean), the residual (i.e., the portion of SST variability “local” to the MDR) only shows evidence for a statistically significant spectral peak in the multidecadal range if you keep the past 40 or more years of data. If you analyze from say 1870-1950 or even 1870-1960, there is no multidecadal spectral peak that is significant relative to a red noise null hypothesis. In other words, its the recent cooling trend from the 50s through the 80s that gives rise to the spectral peak. The “multidecadal” signal is not robust. We then note that this late 20th century relative cooling trend has typically been associated in past work with anthropogenic tropospheric aerosols. Analyses of some recent simulations using the GISS ModelE suggest that there is a huge aerosol cooling (more than -1 C) in the MDR during the crucial Aug-Oct season. This reflects almost -0.5C more cooling than in the global mean for the same season. Accounting for this local and seasonal enhancement of tropos. aerosol cooling, we can describe most of the long-term tropical Atlantic SST without the need to invoke a substantial “multidecadal oscillation” (which, again, is not supported for the MDR by past work on the AMO). Our simple statistical model trained on data through 1969 successfully predicts the subsequent behavior in the following decades, suggesting that our model is perhaps capturing the essence of what is going on. It raises the bar, at the very least, for claims that the recent tropical Atlantic SST trends can be definitively attribued to the AMO. We also show that it is difficult to argue for an AMO signal in long-term records of tropical cyclone activity. Those interested should read the paper for further discussion. –mike]

  21. llewelly:

    10 Most active seasons since 1950 by ACE:

    Year ACE
    2005 248
    1950 243
    1995 228
    2004 225
    1961 205
    1955 199
    1998 182
    1999 177
    2003 175
    1964 170

    56 years of records, 6 of the top 10 within the last 10 years.

  22. Timothy:

    Re: #71 – Yes, but the *really* interesting thing about your list is that the other 4 of the top 10 lie in the relatively narrow range of 1950-1964.

    It strongly suggests that there is a cyclic component to Atlantic hurricane activity, and that the amplitude of this cyclic component is greater than increases due to GW [of ~0.6C globally so far, but Ocean less than this].

    The problem is coming up with a sensible estimate for the increase in hurricane activity for GW 10x the present level, which isn’t that outlandish when you consider the lag in the SSTs.

    It doesn’t help that the resolution of the climate models currently used for century-scale predictions are too coarse to resolve hurricanes. I imagine that in a couple of decades time that won’t be so much of a problem, but I feel that it would be getting a bit too late to make decisions about CO2 reduction by then.

  23. Lynn Vincentnathan:

    RE #4, I read in the Chicago Trib (buried on some back page) during the Clinton administration that VP Gore had worked to make gov energy efficient to the tune of saving $1 billion per year. Too bad I didn’t see it featured on TV or elsewhere. Of course, if people aren’t wasting their money on inefficiency, then companies might lose — unless they too decide to become efficient.

    RE the topic, I’ve been making similar arguments about hurricanes & GW, and that if it’s just natural things increasing them now, then we really have a lot worse to expect in the future, so we really must redouble our efforts to reduce GHGs (& save money to boot).

  24. pat neuman:

    Would a larger tropical imply more hurricanes?

    Tropics are expanding, study finds

    … “The tropics – the globe’s most torrid climate belt – have widened during the past 27 years, expanding toward the poles by an average of about 140 miles, according to new research.” …

    … “These temperature patterns were a surprise. Climate models looking at the effects of global warming have captured the poleward migration of the jet streams. But models also suggested that “the tropics would almost behave like a slab,” warming rapidly but fairly evenly between 35 degrees north and south, notes John Wallace, a University of Washington atmospheric scientist and another member of the team. Instead, the outer tropics are warming faster than the deep tropics.

    “Are the models missing something?” he asks.” …

    [Response: Rasmus and I will be discussing this work, and related modelling work, in Part III of our series on global change and circulation. It’s very interesting and important work. –raypierre]

  25. llewelly:

    Re: #71 – Yes, but the *really* interesting thing about your list is that the other 4 of the top 10 lie in the relatively narrow range of 1950-1964.

    What were those other 4 again?

    1950 243
    1995 228
    1961 205
    1955 199

    1995 is not within the last 10 years, but it is also not within the Dr. Gray’s much beloved 1950-1964 period.

  26. llewelly:

    What were those other 4 again?

    1950 243
    1995 228
    1961 205
    1955 199

    1995 is not within the last 10 years, but it is also not within the Dr. Gray’s much beloved 1950-1964 period.

    After re-reading this post I realized my original post is mistaken; only 5 of the last 10 years are amoung the top 10 years by ACE. My second post was also mistaken; the other 4 are:

    1950 243
    1961 205
    1955 199
    1964 170

    which as Timothy points out are between 1950-1964.

    I apologize for any confusion.

  27. Brian Gordon:

    Re: 69:

    I sent a response to the Post about this. Unfortunately, I can see where the piece is very convincing to someone lacking background. He quotes numerous scientists, mentioning their university or government positions to add credibility, and all say GW is rubbish to greater or lesser degree. If someone threw many of these arguments at me, I would be at a loss. For example:

    “In fact, the correlation between CO2 and temperature that Gore speaks about so confidently is simply non-existent over all meaningful time scales. U of O climate researcher Professor Jan Veizer demonstrated that, over geologic time, the two are not linked at all.”

    As a layperson, this sounds very convincing. A University of Ottawa climate researcher says so, which means, at least, that there is debate in the scientific community. Presumably, U of O would not want their academic reputation damaged by patently false statements by their professors, so the unaware reader could easily believe that the U of O climate department supports this view. I looked up Veizer on U of O’s website, and he published the article in Nature on December 7, 2000, so he qualifies as a credible scientist. Has the research been discredited?
    “Veizerâ��s paper, ‘Evidence for decoupling of atmospheric CO2 and global climate during the Phanerozoic eon’…[c]o-authored with Yves Godderis and Louis M. François, of the Laboratoire de Physique Atmosphérique et Planétaire at the University of Liège in Belgium, the paper points to the unclear causes for the ice ages and warm periods that have punctuated the earthâ��s climate throughout the last 600 million years.”

    “â��The climate pattern mandated by these observations may require reconsideration of the role of CO2 as the principal driving force of climate changes on geological time scales,â�� they concluded.”

    “â��I never said CO2 was not a greenhouse gas,â�� [Veizer] says. â��But there is this one political dogma: CO2 equals global warming, equals climate change, equals disaster. Now, the further you go along this equation, the iffier it is scientifically. But the moment you step away from this dogma you are excommunicated. You are undermining the environmental agenda.â�� He adds that he never intended to attack anyone who wants to preserve the physical integrity of our planet. But he does worry that if such efforts depend on incomplete or flawed science, the predictions could well prove to be inaccurate and the entire environmental agenda could be discredited.”


    [Response: This is a classic case of an unscrupulous newspaper trumpeting a claim that does not imply what it seems to imply (even if it were correct) and moreover has been found to have serious flaws. An honest paper would not do this, but unfortunately wilful malfeasance of this sort is effective, especially when read by people who have a strong personal, ideological or financial interest in believing what their paper is telling them. In this case, the Veizer claim has little or no implications for 20th century warming. He looks at supposed correlations between CO2 and temperature over the grand sweep of time (e.g. Cretaceous hothouse vs. cooling going towards the Pleistocene) and supposedly finds that temperature doesn’t go in lock step with CO2. There are a number of flaws with this — among other things, CO2 isn’t the only influence on climate over this time period, since the changes in continental configurations can also have a big effect. There area also major flaws in his reconstruction of CO2 over the past, and the claim that the temperature proxies used really represent global temperatures is questionable. Veizer (primarily in the GSA paper by Shaviv and Veizer) make the speculative claim that basically cosmic rays explain everything. However, regardless of the validity of Veizer’s work, the National Post article is blatantly misleading when it implies that Veizer’s results contradict Gore’s statements about correlation of CO2 and temperature, because Veizer’s paper applies to the long term changes over the past 600 million years whereas the correlation featured in Gore’s movie applies to the glacial-interglacial cycles of the past 800,000 years. Nobody seriously doubts these correlations, which rely on absolutely firm ice-core data.

    Even if the claims were right, they would have essentially zero implications for anthropogenic global warming, since they do not disprove the basic physics behind the greenhouse effect, or negate the direct evidence for the role of CO2 in 2oth century climate, or the evidence for the validity of a positive water vapor feedback. Even if it turned out to be true that cosmic rays had a significant impact on climate, that wouldn’t negate what we know about climate forcing from direct evidence in the 20th and 21st century. However, the claims by Shaviv and Veizer are highly questionable. Pointers to the discussion, particularly the Rahmstorf et al EOS paper exposing flaws in Veizer’s work, can be found in the post on peer review: . Nir Shaviv claims to have responded to this article, and will no doubt want to re-start the argument on cosmic ray forcings, but I’d ask him not to as we’re unlikely to go through anything different than we did last time. Interested readers can check out the comments under “Thank you for Emitting.”

    Part of the reason articles like the National Post one can happen is that some scientists, e..g. Veizer, have attached unjustified and irresponsible claims to their work. However, I don’t really fault the scientists, though if Rahmstorf et al is right, there may be more to criticize in Veizer than just carelessness and incompleteness. Notwithstanding that, there are real puzzles in past climate, and if somebody wants to put an idea on the table and defend it forcefully, that should be be possible without the risk of the media distorting the implications of the results. I’d hate to see things get to the point where scientists would have to write defensively to avoid every possibility of being misquoted. That would get in the way of the free flow of ideas. All of us who work in past climates are well aware of the remaining mysteries, not least the puzzle of low gradient hothouse climates — recently compounded by results from the first-ever Arctic deep-time seafloor core. Uncertainty of this sort could well imply missing feedbacks that will make the climate’s response to CO2 increases far worse than current models predict. Veizer may have compounded the problem by some of his statements in interviews, but I still put the blame squarely on the reporters and editors of the National Post, who have gone to a lot of trouble to give a completely misleading picture of the state of the science, of which their use of quotes from Veizer is only one among many examples. –raypierre]

    [Response: p.s.: Ray forgot to mention that we have looked in detail at Veizer’s claims at RealClimate here. If you look especially at the second part of this post, you will understand why I find it difficult to believe that Veizer is just an honest scientist with a different opinion, rather than deliberately trying to deceive the public. -stefan]

  28. wayne davidson:

    #69 to be practical especially for those seeking a rapid response, a “standard contrarian playbook” should be written, complete with references and explanations debunking the usual dribble trying to sink in the populace by the help of certain publishers or reporters whom, you never know, might find such a page useful prior to publishing contrarian slime.

  29. Pianoguy:

    Hey, tack on 1995 and drop 1964 – that gives six of the top nine Atlantic hurricane seasons occurring in the past 11 years. It’s a pretty dramatic statistic, and constitutes a serious challenge to the credibility of the natural cycle theory, at least until someone posits a convincing non-GW explanation for why this particular natural cycle is so much worse than previous ones.

    (Improper Use of Statistics Alert) Of course, somebody will seize on the fact that 6 of the top 10 Atlantic hurricane seasons have occurred under Democratic administrations, even though Republicans have controlled the White House for most of this period. It’s easy to see how the Krauthammers and Wills would frame it: Do the Democrats’ tolerant policies embolden hurricanes? Or are Democrats just soft on hurricanes?

    Without the post-2000 season the ratio would be 8 of 10 – we’d pick up a Carter, a Nixon, and, yes, another Clinton. (That Clinton – he just couldn’t control himself!) This strengthens the developing storyline that W isn’t REALLY a conservative! ;-)

  30. Michael Jankowski:

    I’m not sure why Wiki starts with 1950. NOAA’s website has 1851-2004. At a glance, Wiki’s ACE chart looks like the ADO image in the article, which is interesting.

    Throwing 2005 data in there and going back to 1851, the last 10 yrs has 3 of the top 11 (there’s a tie for 10th). The 1950-1964 period also has 3.

    I also found it interesting that the warm and rapidly (anthropogenic?)warming (warm/warming according to CRU 1980s had 3 of the lowest ACE values – 4th (1983), 13th (1982), and 21st lowest (1987) of the 155 years of records. The warm and rapidly (anthropogenic?) warming 1990s had 4 in the bottom 32 (1991, 1993, 1994, and 1997), including one in the last decade.

    FWIW, the 1950-2004 linear trendline of ACE vs Year was slightly negative. It only become slightly positive when wild 2005 was added.

    Also FWIW, the 1851-1906 linear trendline (first 46 yrs of the record, as opposed to the last 46 yrs) of ACE vs Year has a slope of 1.20, while the 1950-2005 trendline has a slope of only 0.19. I find this interesting because the 1851-1906 period saw little-to-no warming (which would’ve been considered mostly “natural” anyhow, right?) according to CRU data, while the 1950-2005 period saw warming of about 0.5 deg C – much/all of which is attributed to anthropogenic sources by many. So during a period of supposedly substantial anthropogenic warming, the ACE trend was half an order of magnitude smaller (and as stated earlier, negative without the inclusion of 2005 data) than a period of basically no warming.

    I don’t think those linear trend-lines say anything conclusive, but I found it interesting that the book-ending equivalent length period of time trends in global temperature, one a period of little “natural” variability and one of substantial “anthropogenic global warming,” didn’t seem to correspond well with trends in ACE. Obviously, that’s blunt analysis tool, but interesting to me nonetheless.

  31. Steve Sadlov:

    NOAA’s mission is to provide forecasts that are as accurate as possible. If that means looking only at oscillations, then that is what they will do. They will do what gets them the best forecast. In their shoes, that is what I would do as well. Attempting to go into somewhat more speculative areas of causality have, in my own experience, been things I’ve tended to regret later. Some of these areas end up being rat holes or even snake pits.

    [Response: At this point, forecasting hurricane trends based on the supposed future of the AMO seems more speculative and less based on fundamental physics than factoring in the contribution of anthropogenic global warming. –raypierre]

  32. Coby:

    In the webpage this blog post is complaining about the only passage I read as relevant to the AMO vs GW hurrican debate is this:

    “Warmer ocean water combined with lower wind shear, weaker easterly trade winds, and a more favorable wind pattern in the mid-levels of the atmosphere are the factors that collectively will favor the development of storms in greater numbers and to greater intensity. Warm water is the energy source for storms while favorable wind patterns limit the wind shear that can tear apart a storm’s building cloud structure.

    This confluence of conditions in the ocean and atmosphere is strongly related to a climate pattern known as the multi-decadal signal, which has been in place since 1995.

    It seems to me that there is one tenuous defense for mentioning the multi-decadal signal and ignoring the possibility that GW is playing a role and that is if this multi-decadal signal is used in their methodolgy for creating the seasonal predictions. This may, if it is the case, imply that this methodology will prove deficient, but it would justify mentioning it and not GW in a public presentation about the upcoming season.

    Anyone know how they derive these storm count predictions?

  33. Urs Neu:

    Re 62,63
    Grant, Michael, can you see any regular signal e.g. in the proxy reconstruction of the AMO of Gray et al. (2004):
    last figure in What would be the period length and what the peaks? I really can’t. Maybe about a 100y signal, but then we are way out of phase now.

  34. Steve Bloom:

    Um, a shift from a 100 year cycle to a 70 year cycle starting in 1900? The whole thing does start to seem a little strained without some explanation for that. As with the PDO, it seems to be a little hard to show that these things don’t just track global temp.

  35. Eli Rabett:

    Raypierre made a good point in his response to #77 about the dangers of being defensive in discussing science. The same point was made about 18 years ago by Jerry Mahlman at one of the Congressional hearings in which Hansen discussed climate models:

    “I did get reviews from OMB. I did receive conclusions from them and others that should have been changed in my testimony, according to their assertion that I found unacceptable, and I said that I find this unacceptable and I insist on having the right to offer my own testimony in my own words.

    We in the scientific community demand the right to be wrong because if we do not have the right to be wrong, we have squelched the right to be creative.”

  36. pat neuman:

    re 81.


    It cannot be said that NOAA’s National Weather Service (NWS) does “what gets them the best forecast” because NWS has not seriously considered climate change influences on weather, climate and hydrology. Not considering climate change influences in operations and procedures development on weather, climate and hydrology is a failure by the agency in meeting its mission to serve in the public interest. For example…

    In a Jan 2001 letter from the U.S. Office of Special Counsel (OSC):

    “You alleged a substantial and specific danger to public health and
    safety and gross mismanagement by officials at the Department of
    Commerce, National Oceanic and Atmospheric Administration (NOAA),
    National Weather Service (NWS), North Central River Forecast Center
    (NCRFC), Chanhassen, Minnesota. … Specifically, you allege that the
    NWS is not handling the issue of global warming in a way that best
    serves the interest of the public. You believe that NWS does not
    communicate the urgency of the problem and the potential dangers of
    global warming to the public.” (Jan 16, 2001 OSC letter to Patrick
    Neuman, PSC File No. DI-00-2100)

    In a Jan 31, 2006 letter to the DOC Office of Inspector General:

    I learned recently that the mission statement for NASA includes “to
    understand and protect our home planet”. In knowing that, I believe
    that my concerns about hydrologic climate change in the Upper Midwest
    and about global warming, which were identified in OSC File No. DI-00-
    2100, need to be discussed with scientists in NASA in order to gain a
    full understanding of the state of the science in Dec 2000, Jan 2001;
    and currently. For that reason, I request that the matters described
    at the beginning of this letter be pursued further. (Letter from
    Patrick Neuman to DOC Office of Inspector General, Jan 31, 2006)

    To my knowledge, there has been no attempt by the DOC Office of Inspector General, NOAA or NASA to see that discussions take place between NOAA and NASA scientists and administrative staff … in order to gain a full understanding of the state of the science in Dec 2000, Jan 2001; and currently.

    Not considering climate change in operations and procedures is thus a failure by all levels of the federal government and their staffs in meeting its fundamental mission and duty which is to serve in the public interest.

  37. llewelly:

    I’m not sure why Wiki starts with 1950. NOAA’s website has 1851-2004.

    From the very same link:

    Starting in 1944, systematic aircraft reconnaissance was commenced for monitoring both tropical cyclones and disturbances that had the potential to develop into tropica cyclones. This is why both Neumann et al. (1993) and Landsea (1993) recommend utilizing data since 1944 for computing climatological statistics.

    1950 is simply the next 10 year boundary. Dr. Gray has used 1950 as starting year for a long time. So do many of NOAA’s tables. I imagine wikipedia’s starting with 1950 is inspired by these factors.

  38. llewelly:

    I don’t think those linear trend-lines say anything conclusive, but I found it interesting that the book-ending equivalent length period of time trends in global temperature, one a period of little “natural” variability and one of substantial “anthropogenic global warming,” didn’t seem to correspond well with trends in ACE. Obviously, that’s blunt analysis tool, but interesting to me nonetheless.

    For a sharper analysis tool, consider additional forcings, such as the downward forcing of certain aerosols. Mike’s paper, which he already linked to, does this. I think this explains the 1970-1994 low activity period, and much of the post 1870 variance quite well.

  39. Brian Gordon:

    Re: 77: Thank you Ray and Stefan for responding to my post about The Post; Ray, your explanation was very helpful. They may publish my letter; they asked for my contact information.

    I agree with Ray that a charismatic speaker who is familiar with the science (and has a high level of integrity) would be very helpful in disarming these debates. However, when the media is actively and deliberately lying….

  40. Stephen Berg:

    Bob Carter et al. are at it again. What a piece of garbage this article is!

    Please shred every part of this piece of propaganda. Please!

  41. Dan Allan:

    Re #80

    Your wrote, “Also FWIW, the 1851-1906 linear trendline (first 46 yrs of the record, as opposed to the last 46 yrs) of ACE vs Year has a slope of 1.20, while the 1950-2005 trendline has a slope of only 0.19. I find this interesting because the 1851-1906 period saw little-to-no warming”

    But if you believe, as other skeptics of the hurricane / AGW link do, that we are in a natural AMO-related cycle high activity, and that it is likely to continue for another ten years, than the more meaningful trendline would be 1950 to 2016, to include the complete set of both high-activity periods. And, if the proponents of AMO explanation are correct that activity will continue to be high, then the trendline will turn out quite positive indeed for the period 1950-2016. So it seems like the purely natural-cycle explanation will still leave unexplained a higher spike this time around versus the previous period of high activiy. Unless, of course, the AMO-based prediction is wrong and activity drops off in the next couple of years. Which neither side is predicting.

  42. wayne davidson:

    The purposeful disconnect that skeptic contrarians use is that AMO is responsible to Hurricane activity, from a small 0.4 C peak to peak SSTA curve, with temperature phases at times not quite fitting with the number of hurricanes, but their strong point is that the AMO went cold between 1960-1995 when, if Global Warming is occuring should be otherwise. They rely on a weak oscillation occuring twice in the last 100 years to make their point, while at the same time GT’s have been striking near +1 C in the Northern Hemisphere. Their favorite disconnect is with land based temperature increases, as if there is a barried at oceanic shore lines, as if air stops flowing
    to the ocean, or land based warmed air has a pittance of any effect with the atmosphere where Hurricanes dwell. As often stated the oceans are different than their atmospheres above, however constant harping of the AMO curve does not mean that the atmosphere has nothing to do with Hurricanes!

  43. Ron Taylor:

    Re #90 – You or someone more qualified than I must respond to the Canada Free Press.

    I sometimes wonder if Gray, Mayfield, et al, have a world view problem. In their world view, climate is a given of the earth and within that given, they try to predict the weather, specifically, hurricanes. So just study the patterns provided by nature to determine the context within which weather is generated. The idea of analyzing the physics of climate opens up too many uncertainties and undermines their sense of control over their own work. It is a little like a creationist biologist trying to analyze biological processes without any reference to or recognition of evolution.

  44. shargash:

    I’m going to embarrass myself with a dumb question: how do we know the Little Ice Age ended around 1850? Temperatures had trended upwards several times during the LIA period, only to trend back down a few decades later. I’m sort of standing the old GW skeptics canard about the little ice age on its head and looking at it from the other direction. Is it possible we’ve been in a cyclical cooling period until recently that was masking some of the effects of GW?

  45. Steve Bloom:

    Re #90 (SB): A quick google shows that this site doesn’t draw the line at crossing into tinfoil hat territory. See for details. Generally there’s little point in direct responses to such obvious propaganda, especially since (according to Wikipedia) their stated site policy of publishing critical letters seems to be less than honest.

  46. Grant:

    Re: #83

    The short answer is, no I don’t.

    I found the same paper (Gray et al. 2004) on reconstructing the AMO from proxy climate records. First of all, the instrumental period (~1870-present) shows *no* real sign of periodicity or pseudo-periodicity. It’s not impossible, but the signal is neither sufficiently coherent, nor sufficiently long, to claim statistical evidence of any cyclic nature.

    The proxy reconstruction shows even *less* evidence of a cyclic nature.

    I’ve done a *lot* of period analysis, and often found that scientists (astronomers, at least) are very prone to claim a “cyclic” phenomenon when there’s no real evidence. This is usually done on the basis of a peak in the Fourier spectrum, usually at very low frequency, which crosses a significance threshold. Climatologists, at least, seem to be aware of the nature of red noise, and apply a stricter test! But the low end of the frequency spectrum is fraught with statistical peril. And it’s well to remember that a “statistically significant” test statistic does *not* demonstrate the existence of a particular type of signal — it merely shows that the null hypothesis is probably not correct. Those low-frequency peaks that barely cross the red-noise critical value do *not* show cyclic behavior, they simply contradict the hypothesis of random, red noise.

    Based on the (admittedly limited) research I’ve reviewed on the AMO, my considered opinion is that if AMO means cyclic behavior with any real level of coherence, then it just ain’t so. The only sense in which I’d admit the reality of the AMO is that there is consistent change in the AMO index on multi-decadal timescales.

  47. Brian Gordon:

    Re: 77, 90, & 93: This article was written by the same person who wrote the article in the National Post that some folks, including me, recently commented on. See post 77 for one point from that article that the RC scientists disassembled.

  48. llewelly:

    I also found it interesting that the warm and rapidly (anthropogenic?)warming (warm/warming according to CRU 1980s had 3 of the lowest ACE values – 4th (1983), 13th (1982), and 21st lowest (1987) of the 155 years of records. The warm and rapidly (anthropogenic?) warming 1990s had 4 in the bottom 32 (1991, 1993, 1994, and 1997), including one in the last decade.

    The 1982-1983 El Nino was the second strongest on record. The 1997-1998 El Nino was the strongest on record. El Nino is known to reduce Atlantic hurricane activity. El Nino also suppressed Atlantic hurricane activity from 1991 to 1994, and in 1987. See here.

    It’s worth noting that AGW may also be making El Ninos stronger and more frequent, and in the Atlantic, this works against other AGW-driven factors that increase hurricane activity. But the factors that increase Atlantic hurricane activity have dominated for the last 11 years. From NOAA’s own summary of the 2005 season:

    During the last eleven years, seasons have averaged 14.7 TS, 8.4 H, and 4.1 MH, and NOAA classifies every season as above normal except for the two El Nino years of 1997 and 2002.

  49. Steve Mauget:

    Re: 19 and the general AMO question (and an earlier post?)

    In studies of intra- to multi-decadal (IMD) variation in U.S. precipitation and
    streamflow I did a few years back (J. Climate v16, pp 2215-2231 & v16, pp 3905-3916) I tried to draw attention to a significant incidence of wet years over the U.S. after the early 1970’s. Specifically, that in a time series of nationally averaged precipitation during 1896-2001, 8 of the 10 wettest years occured after 1972, i.e., the last 29 years of that 106 year record. Using Monte Carlo methods outlined in those papers, I estimated that there was less than a 1% chance of this occuring in a hypothetical stationary climate. I’ve gone round and round with skeptics as to what constitutes a stationary climate, or if stationary climate is a meaningful concept, but thats another story.

    In a subsequent paper in Climatic Change (now in press) I tried to see if I could find a similarly significant wet regime over other continental areas. Turns out a I could: a similar wet regime shows up in the Hulme precipitation data when averaged over a northern Europe – Scandinavian grid region that includes the exit region of the North Atlantic (NA) storm track. In that case 7 of the 10 wettest years in a 98 year record (1901-98) occur after 1978. The North American wet period after the early 1970’s also shows up in the Hulme data. These late century North American and northern European wet regimes were the most significant that I found using a method that analysed running Mann Whitney U statistics. That paper also shows that North American wetness in the last few decades is particularly evident over the North American entrance region to the NA storm track. So the conclusion is that if there was significant wetness in the entrance and exit regions of the NA storm track in the closing decades of the 20th century, there was also a similar wet regime occuring over the oceanic areas of the storm track. The suggested punch line was that these two wet regimes on both sides of the NA were actually one wet regime stretching across the NA. Given their significance, I proposed that the hydrological cycle over the NA storm track was – to borrow a term from the recent baseball scandals – significantly ‘juiced’ in the closing decades of the 20th century.

    The relevance here to the AMO question is that this multi-decadal wet signal was evident in the closing decades of a ~ centennial data records. You might try to attribute the recent wetness to the current AMO phase, but this phase was also present during previous periods in the 20th century when no such wetness was evident. My guess is that this NA wetness is most likely not due to the current phase of the AMO, but to the upward trend that has been removed from the SST records to produce the AMO.

  50. S Molnar:

    Re #90: I’m not an expert on Internet advertising revenue (so someone should correct me if I’m wrong), but I believe it’s standard practice for advertisers to pay for page views, and not just for hits on their ads. Which means that posting a link to an offensive “news” article can make money for the perpetrators. I’m not advocating that links be suppressed, but maybe a link along with a few selections, as in #77, will satisfy those of us who are reluctant to subsidize these people. Naturally, this rule should not apply to not-for-profit sites or articles that are not clearly propaganda.