If you are a RealClimate regular, you are undoubtedly aware of our ongoing interest in the developments in the scientific understanding of potential hurricane-climate change linkages. This is an area of the science where a substantial body of significant new research has emerged even since RealClimate’s inception in late 2004. The scientific research in this area, and the media frenzy and political theatrics that have inescapably followed it, are thoughtfully placed in a broader historical context in a fascinating new book by Chris Mooney entitled Storm World: Hurricanes, Politics, and the Battle over Global Warming. Anyone who is at all interested in the scientific history that has led to our current understanding of Hurricanes and their potential linkages with climate change, will find this book a page turner. The book is a nice complement to Kerry Emanuel’s recent book Divine Wind: The History and Science of Hurricanes (which too is so readable that it lies on our coffee table). Mooney in a sense picks up where Emanuel’s left off. Like Emanuel, he explores the history of the science. But he uses this historical context, and his studies of the personalities of key actors, to explore how the current scientific debate can be traced back to a rift that has emerged over many decades between distinct communities of atmospheric scientists.
Those looking for a polemic (the title of Mooney’s previous book, after all, was “The Republican War on Science”) will be disapointed. Mooney has clearly matured as a writer, and this latest book constitutes his best effort to date. He delivers a thoughtful, non-partisan, and scientifically and historically accurate review of the emergent science exploring the potential influence of climate change on hurricanes.
If you’ve followed the scientific debate on global warming and hurricanes, you will recognize many of the characters in Mooney’s tale (yours truly even gets mentioned a few times :) ). You will also not be surprised to find that William Gray and Kerry Emanuel are the two most prominently featured scientists. In part of course, because they neatly symbolize the two opposing camps in the current debate: contrast for example Emanuel’s work demonstrating a linkage between increasing hurricane intensity and global warming with Gray’s denial of any such link. However, Mooney also traces their respective work back to two different historical schools of thought in the atmospheric science community. On one side are the data-driven empiricists, such as Redfield, Loomis,and Riehl and on the other side the theorists such as Espy, Ferrel and Charney. Gray naturally follows in the tradition of the first group (his Ph.D adviser was Riehl who is sometimes credited as the father of the field of tropical meteorology). Emanuel, a student of Charney, follows in the tradition of the great theorists in atmospheric science. Of course its not quite that simple (and Mooney acknowledges as much). Though Emanuel may perhaps be best known for his theoretical investigations of Hurricane potential intensity, he has also done considerable work analyzing observations. And while best known for his work deducing from observations the parameters governing hurricane genesis, Gray has nonetheless made forays into “theory” (though the results have been decidedly mixed). But the historical context that Mooney provides gives quite a bit of insight into the divergent views that have arisen among partisans in the current hurricane-climate debate.
Mooney covers many of the themes and issues we’ve discussed here before, but adds his own novel interpretations and uncovers a number of key historical details, in the process of stitching together a compelling narrative. Naturally, there is discussion of the hoopla over the active 2004 and 2005 Atlantic hurricane seasons and the aftermath of Katrina. There is extensive discussion of the high-profile studies by Emanuel, Webster, Curry and coworkers (see e.g. here and here) which, eerily coincident with the record-setting 2005 season, first suggested a detectable climate change signal in hurricane behavior. Due attention, in turn, is payed to the active scientific debate these studies have subsequently generated. Mooney describes the debate over the role of natural vs. anthropogenic factors in observed tropical warming trends that have been related to increased hurricane activity, and there is a fair amount of discussion of the partisanship that high-level NOAA administrators have apparently taken in this debate. But, you might ask, what is the bottom line taken by Mooney? What side of the debate does he come down on? Well, again, those looking for a fight will again be disappointed.
Mooney doesn’t come down on any particular ‘side’ of the debate. Instead, he explores the nuances of the scientific findings and views of the various protagonists, and helps the science and the scientists speak for themselves. For example, he gives Bill Gray credit (and rightly so) for the important contributions he has made to our current understanding of hurricane genesis, and shows a somewhat bemused admiration for Gray as a sympathetic relic of a dying breed of atmospheric scientist. But this does not stand in the way of him criticizing Gray (again rightly so) for his curmudgeonly scorn of current generation scientists, and in particular his somewhat irrational rejection of the science supporting an anthropogenic influence on climate. Mooney articulates his criticism gently, by citing Arthur C. Clarke’s “First Law”
When a distinguished elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
There should be no misunderstanding. While Mooney is indeed balanced, he is not completely agnostic either. He recognizes that hurricane characteristics are indeed changing and that, while we may not yet have arrived at definitive answers to the underlying scientific questions, we ought to be concerned.
One could quibble with some details of the book. As we have remarked before, one should be very careful about giving too much weight to any one late-breaking paper. Where there are certainly exceptions where paradigms are dramatically broken on the strength of one groundbreaking paper, science rarely works that way. Instead, scientific understanding generally advances slowly and steadily, based on the results of many independent studies. Mooney however gives quite a bit of weight to the recent article by Kossin et al just published as the book was completed. While this study is undoubtedly an important contribution to the literature, introducing a potentially useful methodology for refining estimates of past tropical cyclone activity in all the major basins, it is hardly the last word (see e.g. the discussion thread in our previous article on the paper). And in places, the implications of that paper are overplayed. For example, Mooney appears in places to imply that the paper’s findings challenge the contention that climate change can be tied to increasing hurricane intensity. While the Kossin et al results do challenge some of the findings described in the work by Webster et al (2005) (i.e., the trends for the Pacific and Indian basins), they reinforce the conclusion of positive intensity trends for the Atlantic. Perhaps more importantly, the paper in no way challenges the Emanuel (2005) study demonstrating a close linkage between warming sea surface temperatures and hurricane intensity for the Atlantic. Indeed, those latter findings have been reinforced, not challenged, by more recent work (e.g. Sriver and Huber).
These are minor quibbles however. Mooney chose to walk a minefield in attempting to assess a controversial and quickly evolving field in climate research. He not only succeeded in producing a fair and accurate description of the science, but provides us a fascinating read as well. There is a good chance the book will achieve a very wide readership. If so, then Mooney has performed a real service by helping communicate a subtle but important topic within the scientific discourse to the person on the street.
Note: Chris Mooney has provided us with an early copy of Storm World and we’re reviewing it before the official publication date–July 9–so you can’t get the book yet in stores. However, you can order it on Amazon.com. You can also visit the book website for more information (including an excerpt of the first chapter).
Just wondering, does the relationship between hurricane and cyclone activity and global warming have as good a correlation as between tree rings and instrumented temperature readings? I ask this since the latest study I have read indicates that global warming would actually reduce power of hurricanes and cyclones since there would be less sheer between cold and warm air.
[Response: Perhaps you are referring to the Vecchi and Soden paper, which we discussed in some detail previously here. It does not however conclude, as you claim, that global warming will reduce the power of hurricanes. It simply argues that impacts of changes in wind shear could at least partially offset increases due to warming sea surface temperatures. -mike]
Speaking of AGW and hurricanes and recent attempts to lenghthen the storm record with proxy data: I don’t see how isotopic studies of the origin of rainfall waters in tree rings or sediment overwash studies can tell us accurately the past frequency or intensity of landfalling hurricanes. For example, we’ve (Texas coast) just received 8″ of rain from a continental low (still parked over central Texas) that is sucking its moisture from the Gulf of Mexico. Wouldn’t future isotopic studies of tree rings peg this rain event as originating from a tropical cyclone of some sort? And BTW, it’s the weak tropical storms that dump the most rain around here as they seem to hang around longer (eg. TS Claudette in 1979 – 38″ on Alvin, Texas). Similarly, the largest recent overwash event on upper Texas coast barrier islands resulted from the high tides and very strong winds of TS Frances which landfalled 180 miles to the south. This relatively weak tropical storm (less than hurricane force winds) was stuck in place for a week while a continental high pressure system set up a wicked barometric gradient. The result was sustained 6-8′ storm tides and more sediment overwash across our local barrier island (Galveston) than during most hurricanes. Am I totally out to lunch on this or what? I’d like to see someone dissect and comment on the spate of past hurricane frequency and intensity studies using real storm data. I don’t think the proxy methods will stand up.
On a semi-related note, the new issue of Rolling Stone contains an interesting and detailed account of the White House’s history in positioning itself on Global Warming during the past six years. Much of what is contained has been discussed in bits and pieces elsewhere, but what makes this particular report interesting is that it gathers together all the varying information and players, laying out the story in a compelling timeline.
Also, Robert Kennedy has a nice piece on what needs to be done to address GW.
Regards,
Mike,
Thanks for your thoughtful review. It’s an entirely accurate summation of the book and I appreciate the kind words.
However let me see your quibble and raise you re: the Kossin study. It was indeed a late breaking study in the context of my timing for writing the book. There have since been other “late breaking” studies, such as Vecchi and Soden, which you have helpfully discussed here at Real Climate.
All these studies taken together show at least two things: 1) there’s a considerable infusion of scientific energy into studying this topic, which is one very positive by-product of the sometimes nasty (but also extremely high profile) debate that followed the publication of the Emanuel and Webster group papers in 2005; 2) many of the precise details of how hurricanes will change in a warmer world (or have changed already) remain contested. That doesn’t mean we shouldn’t worry, or shouldn’t act–but it does mean, as with so many projected climate change impacts, there’s plenty of uncertainty. As I summarize in the book: “global warming, which ought to intensify the average hurricane, could also change the regions of storm formation or the numbers of storms that form in the first place. Despite troubling signs, the evidence simply isn’t in on all of these changes–not yet.”
In this context, I used Kossin’s study as a peg to discuss just how contested the global hurricane intensity records remain, especially in basins other than the Atlantic. As I put it of Kossin’s work:
“At least based upon this slicing of the data, then, the hurricane response to global warming globally didn’t look nearly as predictable as anyone had thought. Kossin’s was just one attempt to reanalyze the contested records, but if nothing else it certainly showed they remained contested.”
So I don’t think I overplayed the results. It’s important to remember that in 2006, both sides in the hurricane-climate argument were awaiting Kossin’s paper and saw it as a first attempt by a neutral arbiter to come in and reanalyze the global hurricane intensity data. From today’s vantage point, by contrast, the Kossin paper (like the Vecchi and Soden paper and much other recent work) helps shift the hurricane-climate detective story to a focus on the Atlantic–which is, I think, a new phase the debate has entered.
Thanks again,
Chris
[Response: Fair enough Chris. Thanks for dropping by w/ the comment. -mike]
Hey Chris,
I should have dropped you a note – as I had run into something interesting. Turns out that hurricanes apparently act as a heat pump sending water from the tropics poleward, feeding into the process by which we are losing the arctic ice cap. Probably not a big contribution, but it would appear that they have a significant global affect – and feed into some of the positive feedback loops which in turn increase their intensity and duration. From there they will undoubtedly contribute to the warming of the subarctic and thus the release of methane by the permafrost. More feedback.
In any case, the review has me sold – particularly with the science and the history of the science and of the individuals who helped to shape it. Looking forward to reading your book. It sounds like something really special.
Re 5: Timothy, sounds like a great topic for a RealClimate post ;>
Actually I commented on the latest Nature paper discussing the heat pump idea, by Sriver and Huber, here. Matthew Huber left a comment to my post:
http://scienceblogs.com/intersection/2007/05/introducing_tropical_storm_bar.php
I also go into more detail on this intriguing notion in the book–so I guess you’ll enjoy that part
Chris Mooney (#6) wrote:
Good grief!
You do like to stay current. I had worried that it might be too recent a development – I don’t remember when exactly it came out. I guess I “shoulda known betta,” as acquaintance of mine from a few years back probably would have said. I will check out the post. And yes, I am looking forward to the book.
As for a post at Real Climate, hopefully one of the contributors will take the hint…
“…has lead…” should be “….has led…..”
[Response: Thanks. Fixed! -mike]
Partisanship by NOAA administrators on the climate change-hurricane debate followed the partisanship by NOAA National Weather Service on climate change-skeptic debate by 12 years which started just after the Gore book on global warming book came out.
The hurricane/tropical cyclone is indeed very interesting.
Tropical cyclones do act as a large mechanism for the transfer of heat, mass and momentum that can significantly impact on weather system thousands of kilometers away
As an example, here in south eastern Australia, tropical cyclones making landfall 5000km away in the north west of the continent can cause heatwaves and extreme forest fire danger if conditions are correct. TCs are warm cored systems, and can transport large amounts of heat. When a TC makes landfall in North Western Australia, it’s dissipation can cause large amounts of extremely hot air to be brought to the south east of the continent and even as far away as New Zealand.
Somewhat conversely, TCs can also bring rain to the south east of Australia, which in our current drought parched stage, is welcome and very important for argiculture.
As far as I know, research into this effect is in its infancy. But if anyone knows of a few good sources of information, I’d love to know.
RE#2, Andrew I’ll second your comment. There is certainly a desire to be able to reconstruct hurricane records using paleoclimate approaches. They are calling this ‘paleotempestology’.
There was another one in Nature recently, by Nyberg et al, that claims that hurricane frequencies were abnormally low in the 1970s and 1980s relative to the past 270 years. They used sand layers in organic-rich sediment cores as proxies for landfalling hurricanes. However, this is limited to one single area. If many more such studies are carried out across the entire region, you might have a reliable dataset… but it still all seems very premature.
The isotopic changes in tree rings due to hurricanes seems to be quite a reach, as you note. Paleoclimatologists have really gone for isotopic studies as a means of getting at previously unanswerable questions, but the limits of the methods are still being worked out, and often involve big and untested assumptions.
At the end of the day, the whole topic is still up in the air. However, all other factors being equal, many studies and observations reveal that hurricanes intensify as they pass over patches of warm water. This has been observed when Atlantic hurricanes intensify as they crossed warm water rings from the Gulf Stream (Effects of a Warm Oceanic Feature on Hurricane Opal, Shay et al 1999 AMS), as well as in the case of Katrina, which intensified rapidly to Cat 5 over an unusually warm Gulf of Mexico.
The problem then is that in a warming climate, all other factors are not equal, such as wind shear and ocean circulation patterns.
However, the claims by certain scientists that the extremely active hurricane seasons of 2004/2005 were due to a cyclic phenomenon in the Atlantic ocean known as the ‘Atlantic Multidecadal Oscillation’ , in which an accelerating Gulf Stream causes warm water to move northward, were quite astounding and also unsupported.
Not only that, but these same scientists (Landsea, Grey et al) attacked the 30-yr trend reported by Emanuel using the faulty data argument. At the same time, they used the hurricane dataset to report a correlation with their AMO stretching back to the turn of the century. (They also loudly attacked climate modelers for not reproducing data on ocean cooling (which turned out to be due to some faulty instruments on Argo floats), and then just as loudly promoted results from models that predicted increased wind shear in the Atlantic.)
The real problem here is that this AMO explanation was picked up and broadcast by the press in a very uncritical manner, usually in these terms: “Surface waters of the Atlantic ocean warm up then cool down in long, subtle cycles. The warm phases dramatically increase the numbers and intensity of hurricanes. The cool phases keep hurricane seasons relatively calm. The ocean entered a warm phase in 1995, and has continued warming ever since.”
This is just bad science and bad science journalism. In any case, ocean data showed a slight slowing of the poleward water transport, not the increase that the AMO explanation called for. It is interesting to note that the AMO explanation still relied on warmer surface waters as the root cause of hurricane intensification. Clearly, warmer waters can produce more intense hurricanes, especially if the depth profile also shows warming in the subsurface layers.
NOAA’s website still has Landsea’s commentary on global warming and hurricanes:
“Because the global earth system is highly complicated, until a relationship between actual storm intensity and tropical climate change is clearly demonstrated, it would be premature to conclude that such a link exists or is significant (from the standpoints of either event or outcome risk) in the context of variability.”
“Additionally, even if a relationship were to be found between trends in sea surface temperature and various measures of tropical cyclone intensity, this would not necessarily mean that the storms of 2004 or their associated damages could be attributed directly or indirectly to increasing greenhouse gas emissions.”
That is a rather odd statement. Not neccessarily? What then would constitute a solid link between greenhouse gas emissions, increased ocean temperatures, and more intense hurricanes?
Dr Gray’s biggest problem is that he completely rejects AGW, in its place he relies on an ocean temperature cycle which guarranties a period of calm and furious hurricanes, of which we are right into the middle of an active period. Unfortunately this idea fell flat along with his forecasts in 2006. His ideas are local centric, anti-model, which are global centric. On the other hand I like Dr Curries approach, which seem to have picked up a global trend in cyclones, but I wont be surprised if cyclone studies including hurricanes fall into Dr Lindzen’s dolldrums (the only thing he constantly argues correctly is a diminishing equator to Pole temp difference slowing eveything down).
However enticing an media savy Hurricanes seem to be, them getting a boost from AGW or not is a weak debate. The real story is AGW itself, far less media prone, hard to understand, harder to explain. This is why many contrarians exploit AGW’s so called fuzzy impact on hurricanes, it has become a popular issue, rather than a scientific one. A distraction for sure, the prime issue is how fast AGW is happening? I am far from satisfied with current projections (they are too conservative) simply because they are bent on the long term. But the distant future is a nebulous world, completely debatable forever, fodder for contrarians content in the uncertainty these discussions forment. Exactly like the hurricane debate, made as uncertain as possible. Yet the world is warming, whether or not another Katrina happens this season is not as solid as current well documented warming trends, which continue to defy “natural variabilty” temperature fluctuations. Wouldn’t it be better if we put our efforts on accurate shorter term temperature projections, say what will happen in 6 months no more than a few years from now, check the models and brag about their accuracy or correct their failures, if the models are continuously correct all contrarian arguments die. The last thing voters want to hear is to save the theoritical world 50 years from now, what they want to know is something like: the call for a warm winter was right 3 years running, climate science is right on! Focus like a laser, otherwise risk sinking in the confusion vortex which will keep on turning whether studies say so or not.
Re # 2 [ I don’t think the proxy methods will stand up.]
Now why haven’t the climatologists and earth scientists thought of this? Hmmm… maybe they have?
Storms and their significance in coastal morph-sedimentary dynamics. Marine Geology 21: 1-5 (2004)
http://wavcis.csi.lsu.edu/pubs/Stone%20et%20al%202004c.pdf?_encoding=UTF8.
AN INVESTIGATION OF ORGANIC-RICH SEDIMENT IN LAKE SHELBY, ALABAMA,
FOR MARKERS OF SEVERE STORM IMPACTS
http://www.geo.ua.edu/asil/LakeShelby_JoeLambert.html (conference presentation; published references at the bottom of the page)
Assessing the Vulnerability of the Alabama GulfCoast to Intense Hurricane Strikes and Forest Firesin the Light of Long-term Climatic Changes
http://www.usgcrp.gov/usgcrp/Library/nationalassessment/gulfcoast/gulfcoast-chapter13.pdf.
RE#12, “Dr Lindzen’s dolldrums: (the only thing he constantly argues correctly is a diminishing equator to Pole temp difference slowing eveything down)”
Wayne, I think the situation here is far more complicated than this. If you had a bar of metal, and placed one end in a warm pool and the other in a cold pool, it’s true that the rate of heat transfer would slow if you warmed up the cold pool.
However, this is a hopeless oversimplification of the equator-to-pole heat transfer system. For starters, there is still the seasonality issue – we can expect lightless northern winters to remain quite cold, but spring might start showing up much earlier. There is also the issue of the atmospheric vs. the oceanic routes of poleward heat transfer, as well as the ongoing heat/moisture exchanges between ocean and atmosphere on the way north.
In other words, Lindzen’s comments are only true for a system dominated by conduction, not for one in which atmospheric convection and ocean currents play such a large role. Scientists are still trying to decide how the poleward heat transport will be affected by global warming – but the rapid changes at the poles seem to involve a lot of heat transport into that region via both the atmosphere and the oceans.
Re #14 Oh my….
“For our part, we have little trouble in accepting that there may well have been an increase in overall atmospheric CO2 by some 25% in the last 100 years (see below), or that this could effectively contribute to the overall anoxia of the planetarian atmosphere.”
Anoxia means no oxygen. So, what the heck is “anoxia of the planetarian atmosphere”?
The second author, Alexandra N. Correa has an HBA degree – what is that? (Honors B.A., perhaps?).
I would love to hear how resident RC AGW skeptics view this document.
The authors of ‘Global Warming’: An Official PseudoScience are obviously quite familiar with pseudoscience- check out their Aetherometry website:
http://www.encyclopedianomadica.org/bin/view/AethMetry/Aetherometry
re: #14 & #15
got to the Akonos website…
Oh, no Wilhem Reich’s “orgone” energy is back for another try
– Free energy!
– Antigravity
– Aether motors!
and what they say about Wikipedia…
By comparison, none of the silly things debunked in RC are even on the scale…
Warmer water contributes to hurricanes, well and good, but I never see mentioned what the effects of the different air temperatures and humidity from global warming are expected to have on hurricanes. Are these trivial? If so, why?
Are the dynamic effects of global warming on hurricanes and other phenomena understood? That is, if the world stabilized at its present temperature I suppose the deep ocean would eventually get warmer, as well as other changes. Are there any general projections of what that would be like?
Re #16, Chuck Booth asks, “The second author, Alexandra N. Correa has an HBA degree – what is that? (Honors B.A., perhaps?).”
Apparently it is an honours business administration degree. A short bio on Alexandra Correa can be found on the aetherometry.com site:
Ms. Alexandra N. Correa, psychologist and sociologist (HBA, York University), associate glassblower, painter and graphic artist, was born in Toronto, Canada, in 1952. She is Senior Partner of Akronos Publishing (Vaughan, Canada), and a member of the International Society of the Friends of Aetherometry (ISFA). Alexandra is co-author of 5 books and over 75 publications, and the co-inventor of several alternative energy systems in the areas of electrodynamics, thermodynamics, and massfree energy.
Aetherometry is a neologism coined by Dr. Paulo Correa and Alexandra Correa to describe their alternative open system, which addresses many scientific fields ( such as physics, chemistry, biophysics) and many controversial fields (such as orgonomy, Kirlian photography, aether theories, alternative theory of De Broglie’s matter waves, Le Sage-type theory of gravity and the aetherometric cancer project). [http://peswiki.com/index.php/Powerpedia:Aetherometry]
I don’t think they are mainstream climatoligists…
This is off-topic, but I cant find any other way to ask a question here, so here goes. My question is whether there is any experimental proof that raising CO2 concentration results in warming in a controled labratory setting? I am talking about hard-core science in a peer reviewed journal. I would imagine that it has been done but I dont know the reference off-hand as I am outside my field. Thanks.
The Australian Bureau of Meteorology has recently been added lots of new products to their website. This page gives you access to an amazing array of maps and other data presentations, including a huge amount of historical data … http://www.bom.gov.au/watl
Maps of tropical cyclone storm tracks since 1906 for the Southern Hemisphere are available here, which is access via the ‘climate data online’ lank at the top-right of that first link.
[[ My question is whether there is any experimental proof that raising CO2 concentration results in warming in a controled labratory setting? I am talking about hard-core science in a peer reviewed journal. I would imagine that it has been done but I dont know the reference off-hand as I am outside my field. Thanks. ]]
Yes, quite a bit of it. Here’s the first one, just to get you started:
Tyndall, John (1861). “On the Absorption and Radiation of Heat by Gases and Vapours…” Philosophical Magazine ser. 4, 22: 169-94, 273-85.
You can also google “HITRAN.”
It would be good to reopen the hurricane climate change discussion. There can easily be cherry picking of feedbacks from the positive ones discussed above, to negative ones such as concentrated convection causing subsidence causing upper troposphere drying. Some discussion of that is here: http://www.lavoisier.com.au/papers/articles/hurricanes1.pdf and models show the same result: e.g. 3088067 http://www.ccsm.ucar.edu/publications/PhD%20and%20Masters%20Theses.htm
I would like to see as comprehensive a discussion of negative and positive feedbacks as possible.
Just an aside from a non-scientist. My recently deceased father-in-law, Katsuyuki “Vic” Ooyama (scroll down to page 5 for a short bio), was a meteorological scientist and developer of numerical computer models (some versions of which are still being used today) regarding the formation, development and tracking of hurricanes. He who worked at the Hurricane Research Division of NOAA/AOML in Miami before his retirement. He was known for his “disagreements” with Professor Gray regarding the efficacy of computer models in the field of atmospheric science in general, and hurricane development, in particular. He once told me that Professor Gray was a very intelligent man blinded by his own inability to see the world outside the narrow focus of his own obsessions. I think what he meant to say was that Gray was a stubborn old curmudgeon with an ego the size of Mt. Everest, but he was far too polite to put it that bluntly.
Re #13 Thanks for the links. Note that in the Thesis link the discussion switches from past storm frequency to hurricane frequency as if all storms were hurricanes. In the few presentations I’ve sat through on storm history reconstruction (I’m an ecologist so I’m coming at this tangentially), I’ve noted this more than once. The speaker conflates storms with hurricanes or they take a relationship built on data from the SE Atlantic coast and at some point in their discussion they seamlessly apply their results to the Gulf coast. Most of the audience knows what is going on and the presentor may roll off a caveat beforehand, but such subtle twists may well be lost on the academic news release editor and the journalist who reports on the latest research. I need to understand AGW and its potential effects on the coastal environment. I depend on RealClimate’s objectivity in all of this. I’ve become dismissive of anyone I catch going beyond their data. My wife knows almost nothing about how a car works, but she knows when a salesman is pumping her full of ….. wrong information.
Ike, No question about hurricane intensity, warmer sst’s will make them stronger. But what happens when the very cause for Hadley cells, when long distance temperature differences become weaker? That is a larger question amongst others. It takes high zenith sun heat to trigger the hurricane season, but it takes also other ingredients such as a wave (a zone of pressure difference), that again is caused by temperature differences. Katrina is a good example:
http://svs.gsfc.nasa.gov/vis/a000000/a003200/a003222/katrina_sst_640x480.mpg
If you look at the larger circulation, Katrina being at center, there seems to be a Clockwise mega circulation, a healthy flow of air reminiscent of a heat engine, knock that off and Katrina becomes a severe thunderstorm around Cuba. Perhaps you made a point, the hurricane season may shift towards winter and spring as global warming continues.
I wonder if its possible to have it so that when the troll comments get removed, the numbering of all the comments don’t all shuffle up one. With the tendency of people in these threads to reply to comment numbers it rapidly becomes difficult to follow as more and more comments get removed.
Today the MetOffice released a forecast for the 2007 Atlantic season: 10 named storms between July and November (70% chance for 7-13 storms), somewhat below the mean over the years 1990-2005.
Although their 2006 forecast wasn’t made public, they seem to did a better forecast than Gray/Klotzbach.
See: http://www.metoffice.gov.uk/weather/tropicalcyclone/northatlantic.html.
[[ There can easily be cherry picking of feedbacks from the positive ones discussed above, to negative ones such as concentrated convection causing subsidence causing upper troposphere drying.]]
There’s not much water vapor in the upper troposphere to begin with. The e-folding scale height for water vapor is about 2 kilometers and the tropopause averages about 11.
But the water vapor in the upper (and middle) toposphere is important due to the unsaturated water vapor spectrum at those altitudes. The feedback from that water vapor is important whether you believe Lindzen or Held and Soden (http://www.gfdl.gov/reference/bibliography/2000/annrev00.pdf)
re14 Ike Solem> …the rapid changes at the poles seem to involve a lot of heat transport into that region via both the atmosphere and the oceans.
What evidence do you have for that? I thought polar heating was caused by GHG and albedo effects, not increased heat transport.
Steve Reynolds (#31) wrote:
I hadn’t heard about the heat transport via the atmosphere, but it didn’t surprise me – that is what the jet streams are all about – a wind caused by an atmospheric temperature differential, given a little bit of a spin. Without the difference in temperature, there will be no stream, therefore it stands to reason that if you increase the temperature of the hot part, you will increase the flow to the cold.
However, with respect to the ocean, there has been increased thermal flux which we have been picking up. Some increased flows we actually weren’t expecting. More recently hurricanes have been implicated as heat pumps responsible for up to 15% of poleward oceanic heat transport.
With respect to the latter, there was a recent article in Nature, “Observational evidence for an ocean heat pump induced by tropical cyclones” by Ryan Sriver and Matthew Huber.
More than half of the following post by Chris Mooney dealt with this:
Introducing Tropical Storm Barbara; New Research on Hurricane-Climate Feedbacks
http://scienceblogs.com/intersection/2007/05/introducing_tropical_storm_bar.php
been lurking a while here, first post.
I’ve had a number of requests from friends/collegues for some “popular” reading on climate change where the underlying science is good, but something a bit lighter than TAR Summary for policymakers. How about some recomendations for other books in addition to Chris Mooneys.
[Response: We’ve discussed various pop sci. books previously here and here. There might be something on our ‘Start here’ page (linked above) as well. – gavin]
Re 28: Fascinating. The UK Met Office forecast uses a very different methodology than Gray, based upon climate models rather than a statistical technique. It’s my recollection as well that the dynamical seasonal forecast wasn’t made public last year. This time around, by contrast, we’re going to be able to watch in real time to see who was right–the statistical forecasters predicting an active year, or the dynamical forecasters predicting a less active one. More here
http://scienceblogs.com/intersection/2007/06/atlantic_seasonal_hurricane_fo.php
Sriver and Huber have an article in Nature (May 31) on the role of tropical cyclones on heat transport across the thermocline in the subtropics. It’s a neat feedback to think about and it might assist modelers in making more accurate GCM’s for a greenhouse world.
http://www.underwatertimes.com/news.php?article_id=57310298146
Got to remind myself to read first and then comment. Maybe someone will find the link useful though.
I wonder how much certainty there is that global warming is NOT causing increased intensity (perhaps also frequency) of storms.
We live in a globally warmed & warming world. To me the burden of proof should be on the skeptics to prove at, say, .05 that GW is NOT causing increased storms. Otherwise, I think we (the laypersons, if not the scientists), can simply assume GW IS causing increased storms, and get on with mitigating GW with all that more urgency.
And even if they can prove at .05 that GW is NOT causing increased storms, we would still have to mitigate with all urgency, since it is causing a lot of other problems. Anyone up to proving that warming does not (eventually) melt ice?
It is refreshing to read this kind of discussion on RC.
My own plethora of Global Warming posts and questions are somehow vindicated by Chris Mooney’s comments to this blog (#4):
> as with so many projected climate change impacts,
> there’s plenty of uncertainty. As I summarize in the book:
> “global warming, which ought to intensify the average
> hurricane, could also change the regions of storm formation
> or the numbers of storms that form in the first place. Despite
> troubling signs, the evidence simply isn’t in on all of these
> changes–not yet.”
The evidence is not in on all of the expected changes. Not yet.
Perhaps we could all agree that, climate-wise, at least about hurricanes there is no evidence (yet) for global warming?
[Response: Chris’s statement is accurate, but you misrepresent it. He certainly does not state or imply that “there is no evidence yet” for an impact of global warming on Hurricane behavior. He is simply pointing out that there are many open scientific questions regarding the details of those impacts. -mike]
Q. Is it the differences in temperature or the absolute temperature that encourages hurricane formation?
Is it the difference in temperature between the ocean surface and the atmosphere, or the absolute temperature of the ocean surface that encourages hurricane formation?
Re: 38
I’ll leave to Chris Mooney to say if I have misrepresented his words.
Let me restate his point: there is no evidence yet of an impact of global warming on the intensity of the average hurricane, on the regions where the tropical storms form and on the number of tropical storms.
A question for Mike then: if the above is true, _what_ evidence is there of an impact of global warming on _any_ characteristic of tropical storms/hurricanes?
In other words, if we can’t tell (yet) about intensity, region of formation and number of storms, what can we tell about global warming and hurricanes?
[Response: We’ve posted this one to make a point, but further nonsense of this sort will be screened out. Why don’t you read what we’ve written on this topic before and educate yourself a bit before making plainly incorrect claims. Start w/ our posts under the Hurricanes category. Chris Mooney doesn’t even remotely conclude what you’ve said above. If we’re fortunate, he might even stop by and comment himself on this. -mike]
No. Compared to rainfall from ordinary thunderstorms (even those originating in the tropics) tropical cyclone rainfall has an unusually low proportion of oxygen-18. I do not know why TC rainfall has this odd property, but paleoclimatologists are quite sure it is detectable in stalagmites , tree rings, and coral. Note both linked studies were done in areas (the Yucatan, and Georgia) that normally receive plenty of rainfall from long-lived thunderstorms, sometimes severe, and often with some amount of tropical moisture. But TC events nonetheless leave a clear oxygen-18 event, because ordinary thunderstorms, even if long-lived or severe, do not produce low oxygen-18 rainfall. I suspect detection of TC events by oxygen-18 ratios is complicated by the fact that oxygen-18 ratios are also affected by summer to winter precipitation ratios, although the very different timescales make it possible to disentangle such issues. Further complicating the use of these proxies is the fact that the deviation in oxygen-18 ratios is affected by the amount of TC rainfall, the distance from the center of the cyclone at which the rain was produced, and the intensity of the cyclone – so I doubt these proxies alone will enable disentangling intensity and rainfall, tnough a large number of samples over an area could reveal information about the track and extent of the TC event. It’s also doubtful that these methods could disentangle multiple severe TC events in the same year and in the same region – but a multiple severe TC events in the same region are quite rare in the Atlantic. (Thus, after 4 hurricanes struck Florida in 4 months in 2004, hurricane scientists calculated that sort of event occurred about once in 400 years, on average. Even during the blow-out-the-walls record breaking season of 2005, Florida received 3 hurricane landfalls – still impressive, but much more common than 4.)
More questions regarding “Paleotempestology”. My oceanography book mentions that the cold-watered depths of the Gulf of Mexico don’t mix well with the Atlantic due to subsurface ridges and that these cold waters owe their origin to ice sheet meltwater poured out by the Mississippi. At some point, with the end of periodic ice ages that AGW promises us, won’t this reservoir of left-over Pleistocene refrigeration become depleted and wouldn’t that greatly exacerbate future sea surface temperature increases and storm behavior?
Re 41: Okay, I’ll oblige: Yes, you misrepresented my words.
There is certainly evidence of global warming’s impact on the intensity of the average hurricane. However, it is evidence that some contest based upon questions about the quality of the data. It would be fair to say there is no “consensus” about the evidence, but not at all fair to say there is no evidence period. An important distinction.
Second, I make the point that theoretical considerations–modeling and hurricane maximum potential intensity theory–lead to an expectation that the average hurricane *will* intensify even if it has not already. You seem to be ignoring this.
Storm regions of formation and numbers are murkier issues. Was the appearance of 2004’s Cyclone Catarina in the South Atlantic an anomaly representative of a truly changing planet, or the kind of event that we would see to have recurred in the past if we had better records? Nobody really knows for sure.
As for storm number changes: There’s an argument going on right now between scientists over whether the Atlantic is seeing a growing number of total storms because of global warming. Meanwhile, modeling results in this area don’t lead to definitive conclusions; as the recent WMO statement puts it, “Although recent climate model simulations project a decrease or no change in global tropical cyclone numbers in a warmer climate there is low confidence in this projection. In addition, it is unknown how tropical cyclone tracks or areas of impact will change in the future.”
The WMO statement is available at
http://www.gfdl.gov/~tk/glob_warm_hurr.html
The statement also says that “If the projected rise in sea level due to global warming occurs, then the vulnerability to tropical cyclone storm surge flooding would increase.”
All in all: The science isn’t settled on this subject (what else is new), but that hardly means that what we know isn’t grounds for being concerned.
Hurricane climate linkages are especially important for those of us who live along the east coast ( as well as the coast of the Gulf of Mexico. I live in lower Manhattan where topographic maps that I’ve seen, show indundation from storm surge of a direct hit of hurricanes labeled with an intensity of category 1 or 2. Anything close to the 5 that hit New Orleans would cause enormous damage and loss of life.
From what I’ve read and heard, rare events,such as prolonged heat waves, very strong storms, and floods of record, will become less rare in a warming Earth.
Of course, if something unlikely like possible slippage happened to the Greenland or West Antarctic ice sheets, we’d be lucky to see the ground floors of our buildings at low tide.
Found an interesting paper looking at a mechanism for the delta in Oxygen-18 for hurricanes. The authors speculate that the main reason hurricanes show this delta is that more of the precipitation is coming from high altitude (depleted in O-18 based on gravitational potential) and in the form of large drops that do not have time to equilibrate wrt O-18 in lower regions of the cloud as they fall. Don’t know how well accepted this mechanism is, but it looked interesting:
http://www.atmos.berkeley.edu/~jelee/paper/jelee_amount_hp_submitted.pdf
re 37 (Lynn): [the burden of proof should be on the skeptics to prove at, say, .05 that GW is NOT causing increased storms. Otherwise, I think we (the laypersons, if not the scientists), can simply assume GW IS causing increased storms, and get on with mitigating GW with all that more urgency.]
So we have to prove the negative which permits you to get about your business of changing everything unencumbered and without even getting your hands dirty. I assume you at least will provide a Scout’s Honor [;-}
Global warming and fire-storms:
In recent years Australia have been hit by increasingly intense, extensive and devastating fires. In some cases these have developed into fire storms. Now Dr Graham Mills, a researcher at the Australian Bureau of Meteorology has found evidence that such fire storms are – at least some of the time – associated with atmospheric conditions that cause extremely dry air to rapidly descend from very high altitudes onto the storm front. See here. I wonder what effect global warming will have on the incidence and intensity of such events?
On another storm topic, it has just been announced that Australia’s tropic Northern Territory is undergoing its coldest July on record. But this is in a period that the Bureau has predicted is likely, based on statistical analysis of historical data and current sea surface conditions, to be warmer than the historical average (see here. The situation is somehow related to the weather system that has delivered a bout of three enormous storms that have hammered Sydney and much of the east coast over the last couple of weeks – see here, here, and here. Interesting.
Re: 44
Thanks to Chris Mooney for responding. Apparently I have read too much in the phrase “the evidence simply ISN’T IN on all of these changes–not yet” (my emphasis).
[edited]
For what is worth, let me state that I am not “ignoring” expectations and concerns. I am simply concentrating on the “evidence” bit.
For example I agree that more instances like 2004’s Catarina would be strong evidence of change.
===========
All in all the science of hurricanes does appear to be much more fun and interesting than the average climate change issue, as there is a debate, a “fight” between different hypothesis, predictions compared to near-future observations, and all that does not always get pre-eminence in the exchanges about models.
Re #48, as I went on to say in #37, “And even if they can prove at .05 that GW is NOT causing increased storms, we would still have to mitigate with all urgency, since it is causing a lot of other problems.”
For instance, there are still other problem GW is causing, such as glacier melt (which even the dalits and possible huge starvation issues for India, China, and many other places dependent on the glacial cycle for irrigation and drinking water. Even dalits (untouchables) in India are aware of this (bec their press is far superior to Western press), and blame us rich countries.
So I really see this debate about GW and bigger storms as sort of academic….the way anthropologists might get all heated up arguing whether it’s Homo sapiens neandertalensis or Homo neandertalensis — even getting into a caveman type fight over it, but completely under the layperson’s radar.
Whether or not GW causes nastier storms may be important for considering GW adaptation policy (and I think the insurance agencies are already making changes based on their idea that GW WILL be causing greater storms, even if the public or the government is not), but it shouldn’t change mitigation policy one iota. We still have to mitigate due to the other reasons.