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.
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).
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).
I find it interesting, too, that the Global Warming camp (which I firmly sit in myself) is quick to allow the AMO and ENSO some influence on hurricanes, while most of the AMO camp does not allow Global Warming even a small foothold. What a shame, especially since people are so influenced by the media.
Each semester I teach a group of about 40 students about climate change. I am amazed this semester (a short summer session) at how many students do not beleive that humans have any influence on climate! We’ll see how that changes by the end of the course.
Thanks for the great posts! I am a devoted reader.
Apparently the Canadian Meteorological and Oceanographic Society is in the “global warming camp”:
New Data Clearly Links Storms and Warming
by Stephen Leahy
June 8, 2006
Inter Press Service
Excerpts (emphasis added):
I was under the impression that there exist some members of the “Global Warming camp” who think that the AMO in the 20th century is a stastical construct and not a real physical phenomena. Eg, the first graph of the “AMO index” is a “detrended sea surface temperature anomaly”, but the “detrending” is a removal of a linear trend, and not of the global mean surface temperature trend. So my impression was that if you detrended by removing the global warming signal, the AMO cycle would become much less clear…
I have not done this analysis myself, I’d be curious as to how widespread this “statistical construct” opinion is, and what the AMO index would look like with after more appropriate “detrending”.
The US accounts for 25% of the world’s pollution and this was going on when Al Gore was vice president. How pathetic.
[Response: But neither Gore nor Clinton had enough control over Congress to do anything about it. I can fault Clinton for not making this a higher priority issue, but the executive branch can’t bear the burden of the blame for the lack of action.. A carbon tax idea was floated in the early days of the Clinton administration but went over like a uranium balloon. Republican obstructionism may have been (and continues to be) in large measure to blame, but Democrats have a lot of populist baggage on energy issues also. Local interests and labor alignment in Michigan have helped block more stringent auto fuel economy standards, Democrats have led the charge for reduced gas taxes and other ways to keep down energy prices (very counter-productive for conservation, and for the budget deficit as well) and Democratic Illinois is big on coal and lukewarm to CO2 emissions controls. Both parties need to change. There may be some difference between conservatives and liberals on the right kind of policy response to avoiding global warming, but a consensus needs to emerge among both parties that there really truly does need to be a policy response, and that it should be mostly emissions reduction rather than the fata morgana of adaptation. -raypierre]
If the Hadley Cells gravitate outwards due to GW, wouldn’t this also cause the ITCZ to move northward too, and thus widen the overall hurricane track? And given increased SSTs and rising overall atmospheric water vapor content, wouldn’t it be possible for hurricane season to become year-round? Lastly, wouldn’t we see a corresponding increase in the severity of non-tropical storms similar to that recently seen in tropical storms?
They’ve been instructed to form it as an either/or argument. It’s a political appointee at the helm responsible for the disconnect. Natural is favored, because there’s nothing that can be done about that. RE# 3 Actually pollution standards have beeb relaxed since Clinton/Gore left office, but the idea that 0 emissions would be Gore’s test is ludicrous.
re: 3. Yet another “hit and run”, cherry-picking post by someone who heard or read his supposed point from an un-scientific source and who won’t be back after their point is disproved, just like the other day. Coincidence? Probably not.
The fact is that global warming began long before the Clinton administration. Most adminstrations since 1970, when the human-caused warming really became apparent relative to natural causes, have been Republican. ;-)
The real problem is lack of any concise record of Atlantic hurricanes over a time period longer then 100 years (and even then, it’s shaky). While we have other data to look at temperature, and by looking at proxies can figure out a reasonable interpretation for the temperature for years and years, there exists no credible way to do something like this for hurricane patterns.
GW most likley has some kind of effect, just because of more availible energy. However, without longer-term records, things like the AMO are not as statistically significant as they are wanted to be.
…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.
Why would not you do this “objective” analysis by yourself and show us the results, if you are so sure that the AMO camp is so totally wrong? It seems that you already formed an opinion that you “objectively” know the correct answer, before even trying. Sorry, but this is what people call a “declarative statement.” I do not see anything “objective” about such cheap shots. If you have an argument, provide it. The bottom line is that you do not.
A propos: Can there be anything on this planet that is NOT related to the dreaded global warming?
“A propos: Can there be anything on this planet that is NOT related to the dreaded global warming?”
How about earthquakes/tsunamis (sorry, Michael Crichton)
What about the recent work by Emanuel and Mann?
http://dsc.discovery.com/news/briefs/20060605/hurricane_pla.html?source=rss
Looks like this severely undercuts the AMO argument.
(Apparently, this hasn’t been published yet — I just checked the latest online edition of EOS.)
[Response: It’s out now. If I may summarize and oversimply some very deep conclusions, it would be as this: A lot of what is being called the AMO is really just global warming by another name. –raypierre]
re 8
nope:
Climate change: Tearing the Earth apart?
27 May 2006
Bill McGuire
Magazine issue 2553
Never mind the weather, climate change could rip up the very fabric of our planet, says Bill McGuire
http://www.newscientist.com/article/mg19025531.300.html
… There was not one mention of the possibility of global warming being a partial factor for these changes …
This brings back memories. For the Upper Midwest Spring Flood Outlook in March of 2000, the mention of climate change and global warming was stripped from the Public Release by NWS management (Development and Operations Hydrologist and the Hydrologist in Charge of NOAA’s National Weather Service’s North Central River Forecast Center located in Chanhassen, MN). 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.
Re: #7
> Why would not you do this “objective” analysis by yourself and show us the results, if you are so sure that
> the AMO camp is so totally wrong?
Generally, the person making the assertion is required to produce the evidence. I could claim that cyclical changes in the fundamental phlostigen constants are causing the increase, but why should Professor Crowley be forced to disprove my assertion when I have not demonstrated the existence of phlostigen in the first place? I mean if he has a lot of free time, I’d be happy to point him in the right direction, but I also understand that he may be busy ;-).
The Wall Street Journal reported today (June 9, page A11) that melting glaciers promote earthquakes and volcanoes. Glacier retreat induces tectonic activity by “isotopic rebound”. Perhaps worldwide melting of glaciers by global warming will increase the incidence of volcanic eruptions and earthquakes, as well as increasing the intensity of hurricanes.
“A propos: Can there be anything on this planet that is NOT related to the dreaded global warming? ”
Many things, but this is a thermodynamical evidence that the hurricanes strength increases with the delta of temperature between the warm (SST) and the cold (upper troposhere) sources.
It’s very strange that NOAA doesn’t recognize it.
GH effect increases SST and reduces upper troposphere’s temperature.
Increased thermodynamical yield is not the only reason for the strength of the hurricanes (winds regime is also important), however it’s a necessary condition.
Maybe it’s not easy to detect the trend behind the noise of chaotic and cyclic variability.
How Melting Glaciers Alter Earth’s Surface, Spur Quakes, Volcanoes” – “Imagine the surface of Earth as a giant trampoline that accumulated a slab of ice over the winter, and you can get a sense of what a growing number of scientists say is in store for the planet as glaciers keep melting. Once the trampoline’s ice turns to water that drips over the edges in the warm days of spring, the concave elastic slowly rebounds to its original flat shape. That’s how Earth responds as glaciers retreat, and the consequences promise to be … interesting.” (Wall Street Journal)
See even earthquakes are caused by GW
I am trying to get a better understanding of the greenhouse gas effect, and I should be grateful if anyone could provide the information I need, or give a website reference.
1. What is the absorption cross section of a CO2 molecule in the atmosphere for a 10 micron infrared photon?
2. How many excited states can the CO2 molecule exist in at the same time?
3. What is the relaxation time of these states?
4. What is the “down time”, after relaxation, before the molecule can absorb another photon?
[Response: If you’re just getting started on understanding the greenhouse effect, this is the wrong place to start. Most of these questions are essentially irrelevant to an understanding of the greenhouse effect, or at most involve only very technical or arcane refinements of the understandingof the basic mechanism. For a start, take a look at David Archer’s book, then maybe Chapter 3 and (eventuallly) Chapter 4 of my book (on my web site, linked via teaching->geosci232). –raypierre]
I am curious about the specific statistical tests you have in mind. What precisely is the testable null hypothesis that AMO provides? What alternative hypothesis (preferably with only one tail) does global warming theory provide? Also, how many years of data are likely to be required before we can see a significant result?
Could someone give me a link to a graph where I can see the actual temperature difference between the two SST and the upper troposphere. I’d like to see it for myself (I trust my eyes :) )?
Also, the US or Europe is not the problem, if I read the IPCC pages correctly. We already minimized our CO2 and CH4 output, while third world countries are increasing (we are already on the lower end). Or did I read the graphs wrong, if so, how? (IPCC 2001)
[Response: On a per-capita basis even Europe is still way above the third world in CO2 emissions, and the US is off the charts; a relatively high population plus a large per person emission makes the US a major culprit. However, the large population of the developing world combined with potentially growing per capita emissions makes the developing world a long-term threat to climate. On the third hand, the per-GDP CO2 emission in China is a lot above Europe or the US, so with efficiency improvements their economy could grow a lot without increasing their CO2 emissions. –raypierre]
Any decent book on quaternary geology will dispell the disinformation offered in today’s The Wall Street Journal. The areas covered by massive ice caps during the last glacial maximum are still rebounding. Rates on on the order of centimeters per century. Notice any earthquakes or volcanoes in Canada or Scandinavia?
Is it possible to get higher resolutions of the two figures displayed in the post above?
Cheers! :)
First, let me at least claim a bit of credit for being early to point out in early April that everyone (perhaps I exaggerated) makes the mistake of insisting on OR (natural cycles OR anthropic climate change) as the issue wrt the upcoming hurricane season. AND (natural cycles AND anthropic climate change)is what is really worrying for this year.
Then let me start answering Aubrey Banner
1. What is the absorption cross section of a CO2 molecule in the atmosphere for a 10 micron infrared photon?
See JQRST 48 (1992) 537 or the HITRAN data base. The question is not very precise because, first of all, the center of the bending vibrational band is ~ 670 cm-1 which is a lot closer to 14 microns, second, since the spectrum is composed of very narrow lines, if a photon frequency is on line center the absorption coefficient is a LOT higher then if the frequency is between lines.
2. How many excited states can the CO2 molecule exist in at the same time?
One, but each CO2 molecule can be in a different vibrational and rotational state. Under normal atmospheric conditions the distribution of CO2 molecules among the states is determined by the local temperature. At room temperature about 6% of the CO2 molecules are vibrational excited.
3. What is the relaxation time of these states?
Again, not well defined. The radiative relaxation time is much longer than the atmospheric relaxation time, which is determined by the collision rate. In practice the collisional relaxation time under atmospheric conditions is ~microseconds. The mean time between collisions at atmospheric pressure is of the order of a nanosecond.
4. What is the “down time”, after relaxation, before the molecule can absorb another photon?
Zilch.
Re#20
It isn’t very difficult to find some data about SST and lower strato (or upper tropo).
For example in the superb site of NOAA.
For the SST: http://www.ncdc.noaa.gov/img/climate/research/2005/ann/glob_jan-dec_pg.gif
Anf for the strato: http://www.ncdc.noaa.gov/img/climate/research/2005/ann/st-global-jan-dec-pg.gif
RE #11:
Dust in the area of hurricane birth also (mainly?) comes from the Sahara and the Sahel grasslands south of the great desert, in addition to the industrialized countries further north. As such the dust amount is dependent on many factors, i.e. the easterly winds, a variable regional rains regime and the growing population pressure leading to more intensive agriculture and larger numbers of cattle. The SeaWifs maps the Saharan dust clouds, as will some newer satellites.
In addition to cooling the sea surface temperature, a high dust content also modifies the cumulus cloud process. During the occasional strong outpourings of Saharan dust, hurricanes are not started – an observation already used by the forecasters (but apparently not yet modeled properly). Understanding dust generation and transport is a key goal of the AMMA campaign, now underway. http://www.joss.ucar.edu/amma/amma_summary.htm
Increasing amounts of dust from the desert would counter the impact of rising SST (I have seen somewhere that the number of hurricanes on the Atlantic has not risen, although some increase is found of tropical storms in the Pacific). On the other hand, there are contradictory forecasts on the precipitation climate in Western and Central Africa.
An interesting question is, of course: Is there a critical initial step or combination of circumstances in the hurricane start-up, which could be seen as a separate stage from its subsequent intensification?
Regrettably, there might be a headline: “Famine in Africa saves American lives!”
Re #23
Many thanks, Eli, for your help.
RE: # 21 Benson says “Any decent book on quaternary geology will dispell the disinformation offered in today’s The Wall Street Journal-. Notice any earthquakes or volcanoes in Canada or Scandinavia?”
Actually, yes. NASA’s Jeanne Sauber says, “Historically, when big ice masses started to retreat, the number of earthquakes increased. More than 10,000 years ago, at the end of the great ice age, big earthquakes occurred in Scandinavia as the large glaciers began to melt. In Canada, many more moderate earthquakes occurred as ice sheets melted there.” The weight of a large glacier on top of these active earthquake areas can help keep things stable. As glaciers melt they lighten the load on the Earth’s crust, allowing tectonic plates to move more freely.
The researchers believe that a 1979 earthquake in southern Alaska, called the St. Elias earthquake, was promoted by wasting glaciers in the area.
http://www.nasa.gov/centers/goddard/news/topstory/2004/0715glacierquakes.html
Re#24:
Thanks for the graphs. However, those are Annomalies in the mean. Are there also graphs on the actual geographical variance and not the mean?
It seems that the stratosphere is cooling? How will this affect climate?
Can the cooling trend of the stratosphere affect the warming or rather trade with the warming of the lower level?
Since warmer air is expanding due to thermodynamics (or with v=const. pressure will go up), it could exchange with the lower temperature in the stratosphere, or is there some other effect in it?
Re 27:
I presume someone will answer more completely, but quickly, stratospheric cooling is a prediction of global warming theory. If I am not mistaken, the degree of cooling is consistent with what models predict.
[Response: Yes, but I think more of it is from Ozone – William]
[Response: Almost right. The cooling seen in the lower stratospheric MSU 4 record is indeed mostly due to ozone depletion (interrupted by a couple of big volcanoes), but the cooling further up is indeed consistent with the expected forcings from greenhouse gases. – gavin]
#14, that’s isostatic rebound.
http://www.boston.com/news/science/articles/2006/06/09/nasa_shelves_climate_satellites/?page=2
Looks like some agencies will have even fewer tools available to look at the problem. Will these delays and data gaps relate to AMO investigations specifically? Certainly they’ll affect hurricane science. I don’t think we need more information to begin acting, though it would be nice. Skeptics who say not enough is known (for the purposes of deviating from business as usual) should be really up in arms, no?
Re#28
For the regional SST look at this link:
http://okdk.kishou.go.jp/MRCS_SV12/figures/png/7_sst_trend/sst_trend_3.PNG
As you can see, North Atlantic SST much increased in the last decade.
For the lower stratosphere cooling it’s a consequence of the GW by GHG effect.
(and also ozone depletion).
Another consequence is the decreasing of the north-south thermal gradient.
Thus, it’s probable that the thermal vertical exchange will increase to the detriment of the latitudinal exchange.
The consequence is a more frequent deep convection (also more frequent hurricanes).
An obstacle to this is the temperature increasing of the middle troposphere (more important than the surface).
But it’s also very probable than high SST will induce an higher instability of the atmospheric layer.
In addressing the question of the effects of greenhouse gases on Atlantic tropical storms, it might clarify (and even partially defuse) the controversy to lump internal variability together with other forced responses (particularly aerosols), rather than to focus on internal variability vs the total forced response. No one would claim that the non-monotonic behavior of the temperature time series, globally or in the tropical Atlantic, is due to greenhouse gases! So whether we refer to these multi-decadal fluctuations as the AMO or not, or think that they are forced or free, does not strike me as central to the issue at hand. In addition, both internal variability and aerosol forcing are likely to affect tropical storms in large part though changes in ocean temperature gradients (thereby changing ITCZ position and vertical shear), while greenhouse gases likely exert their influence by more uniformly changing ocean and tropospheric temperatures, so the physics of the problem may suggest this decomposition as more natural as well.
Re #s 21 and 27: Just to add that the reference to volcanos was for ones that already exist. Such an effect isn’t terribly surprising since volcano magma chambers aren’t all that far below the surface.
28 re stratosphere, see also
http://mustelid.blogspot.com/2005/03/why-does-stratosphere-cool-under-gw.html
“… the reason that the real atmosphere has a stratosphere is because of ozone absorbing UV, thereby warming that portion of the upper atmosphere”
The temperature (warmer above) is pictured here:
http://www.uwsp.edu/geo/faculty/ritter/images/atmosphere/structure_composition/atmospheric_structure.jpg
[Response: Actually, planets have stratospheres even without ozone or major solar absorption effects. The stratosphere is just what you get where convection hasn’t stirred things up. Without solar absorption in situ, you’d still have a stratosphere, just not one where the temperature goes up with height. It would go down with height, but slowly enough that there would still be strong stable stratification. Venus, Mars and Jupiter all have stratospheres, only weakly affected by solar absorption (due to near-IR bands of CO2 in the former two cases.). Titan has a stratosphere, too, but it warms with height due to absorption by organic haze. –raypierre]
Re #21 and #27: Thank you, Michael Seward and Steve Bloom. During LGM and the subsequent melting of the ice, there were no volcanoes in major ice covered areas, other than those associated with the so-called Ring of Fire. That is, Kamchatka and Alaska. In particular, Mt. Elias is on the Gulf of Alaska, a highly tectonically active portion of the Ring of Fire. I opine that a mere glacier would not effect the triggering of an earthquake by more than a few decades, at most. Consider the forces and masses involved!
Jeanne Sauber’s quote is not information to be found in any of the books on geology or the last glaciation I have read. Admittedly, these are somewhat older books, but one would think that geologists would at least mention a major earthquake in Scandinavia. Perhaps the data is new. I would want to read a paper explaining the observations which give rise to her remarks before I’ll completely accept them. One’s persons “major” earthquake turns out to be only magnitude 6. Now a magnitude 6 earthquake is no fun at all to experience, but not “major” to me.
Mostly what happened, and continues to happen, is isostatic rebound. I am perfectly prepared to accept that some rather small, say magnitude 2, earthquakes occasionally may occur. However, the Canadian shield is usually consided to be among the most tectonically passive areas in the world, despite the tremendous rebound still occuring in Hudson’s Bay…
Well, all this is off-topic. The point was one shouldn’t believe everything you read, especially in The Wall Street Journal.
Re 34
Are there no volcanoes on the Antarctic Peninsula?
The best illustration I know for the relative roles of ozone depletion and increase greenhouse gas concentrations can be found here
http://www.gfdl.noaa.gov/aboutus/milestones/ozone.html
My simple explanation for stratospheric cooling can be found at
http://rabett.blogspot.com/2006/02/why-does-stratosphere-cool-while.html
William’s explanation can be found here
http://mustelid.blogspot.com/2005/03/why-does-stratosphere-cool-under-gw.html
Needless to say he don’t like mine and I don’t like his. I think my explanation got a push forward from
http://www.gfdl.noaa.gov/reference/bibliography/2005/bjs0501.pdf
and maybe here
http://www.gfdl.noaa.gov/reference/bibliography/2006/vr0601.pdf
We report, you decide
Re #34: It shouldn’t be surprising that melting of a glacier might cause earthquakes. After all, the filling of reservoirs apparently has triggered earthquakes, one being the 1975 Oroville quake (5.7) in Northern California:
http://www.newton.dep.anl.gov/askasci/gen99/gen99051.htm
The larger 1967 Konya Dam quake in India (6.9 or so resulting in 200 deaths in this rural area) also was attributed to the additional weight of water in the reservoir, and the shaking has continued for three decades:
http://www.hubcat.org/Adrienne/Koyna/Koyna_physical.htm
Seismic activity also has increased since filling began of China’s Three Gorges reservoir:
http://www.probeinternational.org/pi/index.cfm?DSP=content&ContentID=15282
So in the right location, the addition or removal of a block of water or ice is known to result in fairly significant earthquakes.
Re #34: This research implicated the Laurentide ice sheet in the recent great earthquakes on the New Madrid fault. The same authors drew a similar conclusion about an area off Norway. Here is something along the same lines on volcanos in Iceland.
I was rather taken aback by the following statement from a NOAA administrator, reported in the NYT article:
—–
Stanley B. Goldenberg, a meteorologist with the Hurricane Research Division of the National Oceanic and Atmospheric Administration who has expressed skepticism about any connection between global warming and hurricane intensity, said he had not seen the new papers but had read nothing in other recent research to change his view.
“There’s going to be an endless series of articles from this circle that is embracing this new theology built on very flimsy interpretation” of hurricane data, Mr. Goldenberg said. “If global warming is having an effect on hurricanes, I certainly wouldn’t base it on the articles I’ve seen.”
——
“This circle” in the quote refers to a large number of professors at top atmospheric science departments, at least one of whom has written the definitive textbook on atmospheric convection and was so talented that the department awarded him a PhD for something he submitted as a Masters thesis; another has won numerous awards for his work on tropical meteorology. If NOAA isn’t willing to listen to “this circle” I shudder at the thought of whom they are listening to. As noted already, “This circle” is willing to admit uncertainties in the analysis and a partial role of natural variability. It’s “The Other Circle” that is unwilling to even admit the possibility of an effect of global warming. They repeatedly express complete and unqualified faith in the tenet that only natural variability accounts for the recently increasing strength of hurricanes.
So, which circle is it that truly subscribes to a “new theology?”
Re #41
Yes this comment is very disturbing as your and my tax dollars have been going to them, (whether or not we get funding) and I wholeheartedly agree with what NOAA/NWS has done in the past. But to my astonishment, I will now have to jump off thier ship (the Titanic) if they are to make such political potent statements.
I used to think of the government as for all of us. NOAA’s mission statement is to “protect life and property”, NASA’s is “space exploration and to protect Planet Earth”. They better get their houses in order here or there’s going to be trouble and not neccesarily from pissed off tax payers in the know and ahead of thier politcal curve.
I also find their cutting of the funding for Hurricane research environmental monitoring satellites disturbing. Somebody should graph that one!
Sticking one’s head in the sand does not change reality. Having said this I know all of NOAA’s NWS workforce is not on board with such scientific ignorance.
Calling all congressman and senators – now is not the time to go to sleep on this research as to not upset a particular lobby. Vote by paper!
RH
Re 41 and Goldenberg’s comments:
He seems to know in advance that anything the “circle” says is wrong even without examining their arguments and criticizing them in detail. The articles in in Realclimate represent a different attitude. No idea is automatically rejected based on its source. There have to be convivncing arguments for so doing.
#41, The likely connection between Hurricanes and Global Warming is right in front of us, the Hurricane season does not occur during winter when SST and ST’s are colder, so for any meteorologist to say that there is no possible connection is ludicrous.
Goldenberg certainly is active in hurricane research, but he also is deep in the Landsea ocean (you can google his CV). If, on this sunny Sunday, one were inclined to be cynical, one would these attacks as an orchestrated tactical response, extending from Bill Gray on the rabid side to he who must not be named on the more reasonable end, coordinated through CEI and NOAA.
There are two ways of dealing with this. There is the scientific way, which Leonard Evans points to, where arguments and data are discussed and reconciled. A fair amount of barracking is allowed, some elegant, some brutal. Unfortunately as we have seen with climate change, this neither reaches nor is understood by the public until it is pretty close to too late.
The other is to turn the tactic back on the attackers. The line of attack is clear and correct. Joel Achenbach started down that track in his recent Washington Post article. Show them as rabid dinosaurs, whom science has passed by. They are placidly grazing beasts ignoring the dangers around them and us. And above all, when they reply with wounded bleating DO NOT APOLOGISE http://tinyurl.com/create.php Point them to some of the things that the Gray’s of the world have uttered. These folks are neither your friends nor your colleagues, but want you to think that they are in order to exploit you for their purposes.
Re 41 and the OP,
I look forward to RP Jr.’s criticism of this. He took the NYT to task (IMO a bit unfairly) for giving less airtime to the “it’s natural” camp in this debate.
Roger? Is one forthcoming? I will look for an oppurtunity to poke him over at his place as it is not certain he will read this.
Eli, re stratosphere, see also response by Ray’s (comment on my 35)?
My 35 was in reply to Max’s question in 28 — the stratosphere’s not going to exchange places with the lower atmosphere because the lower atmosphere warms and the stratosphere cools; they’re not changing enough to swap places.
Am I alone in being disappointed in the growing ratio of rhetoric to rational discussion of science on this site (especially on this topic)?
Here is my attempt at defining the crux of the scientific controversy about Atlantic hurricanes and global warming (putting aside the key question of data quality). This is in part a reaction to Tom’s call at the top of this thread for a “detection and attribution approach to the alternative explanation of the AMO”, which I did not understand, and expands on my comment #33.
There are two distinct issues, at least, and it helps to keep them clearly distinguished.
1) Is the effect of the ocean on tropical storm statistics primarily local (with tropical Atlantic temperatures controlling Atlantic storm statistics) or are nonlocal effects of comparable, or even greater, significance? The best example we have of non-locality is El-Nino, wherein changes in temperature in the Pacific clearly influence the Atlantic storm season, through some combination of changes in vertical shears and a tropospheric warming that stabilizes the atmosphere to convection over the Atlantic. One can simplify this dynamics to say that it is the result of warming in the Pacific unaccompanied by comparable warming in the Atlantic. Analogous things can happen on multi-decadal timescales. A session at the most recent AGU Spring meeting was devoted to the possibility, suggested by models and paleo evidence, that the latitude of the
ITCZ can be displaced by perturbing the system in middle and high latitudes. ITCZ position is thought to be important for Atlantic tropical storm statistics. Sahel rainfall is also related in part to ITCZ displacements and is correlated with Atlantic storminess. Although there is controversy about the details, models are in general agreement that the Sahel drought of the 1970-80’s can be simulated in large part if one cools the North Atlantic with respect to the rest of the world oceans.
Researchers who have traditionally focused on seasonal or shorter time scales talk about things like vertical shear, ITCZ latitude and African wave characteristics as centrally important. To the extent that these are controlled by ocean temperatures they are likely to be related to differential changes in ocean temperature and not simply local absolute temperatures over the tropical Atlantic. Is the data good enough to clearly justify the superiority of the local perspective on the SST/tropical storm link. I am not sure. In any case, the possibility of non-local control needs to be addressed more systematically to make contact with this other community of researchers.
2) Given an oceanic temperature predictor of tropical storm statistics, can one decompose the variations in this predictor over the 20th century into parts contributed by a) greenhouse gases, b) other external forcing, and c) internal variability? This question seems to be framed typically as forced (a+b) versus free (c). Both (b) and (c) are expected to contribute to differential oceanic temperature changes varying non-monotonically in time, with (a) providing a somewhat more spatially uniform and monotonic background. For that reason, I suggested in #33 that it may make sense to frame the question as (a) vs (b+c). Also, because of limited confidence in the multi-decadal dynamics of our climate models and the uncertainty in aerosol forcing, one can foresee the problem of separating (b) from (c) as being with us for some time. And, of course, it is (a) that is primarily needed to project to the end of the 21st century.
Would the results of such an attribution study be sensitive even to a rather modest admixture of non-local effects into the predictor?
[Response:I suppose that by differential oceanic temperature you mean the same thing as I when I say spatial SST gradients (i.e. how sea surface temperature varies geographically)? If this is the case, then there is also the question if the statistics of cyclogenesis, pressure depressions (intensity), or associated rainfall vary linearly or non-linearly as the absolute levels of SST change (maybe since the saturated water vapour pressure is not a linear function in temperature?). One admitedly hand waving arguement is that if the absolute SST is lower than 20C, then no SST gradients would not suffice for tropical cyclone generation. That said, I don’t know the answer to this, and I’m not aware that this question has been addressed. -rasmus]
I like to debate the finer points of this subject, where there might be legitimate theories to explore and expand on, but when contrarians, either lay or scientist contrarians propose dumb ideas, they should be responded with the clearest logic possible. I see how bad ideas remain in the populace, how sound science gets buried, as another recent example, a contrarian proponent having the ears of millions suggests something really dumb like where are those 200,000 year old cars?
http://mediamatters.org/items/200606080005
The media outlet carrying this contrarian is of course not responsible for what he says, but may care about very basic science which just got trashed, no immediate scientific response is where they the contrarian gets away with transforming science into nonsense. AGW theory gets slashed 1000 times over before a response is done, and the dumb idea grows legs.
[Response: It’s appalling that something like this would come from a CNN news host (Glenn Beck, albeit on his radio show rather than on CNN itself). I’d expect it from Fox or from Milloy, but that such bad science even gets play from CNN people is just awful. Not only does Beck compare Gore to Hitler, but he gets the science even more egregiously wrong than George Will or professional contrarians such as Pat Michaels. To begin with, Beck claims that because CO2 varied naturally in the past, there’s no case for the present rise being due to human action — a claim that is equivalent to casting doubt on the human cause of the recent CO2 rise. Even contrarians admit that there’s no doubt about the human cause of the recent CO2 rise, at least when they are talking to people who are not completely naive. Beck further claims that if CO2 were to rise as much as Gore said it would, “then the temperature here on planet Earth will be about 400,000 degrees. We’ll be the sun; we’ll be the frickin sun. ” — a claim that is nowhere in Gore’s movie or book, is utter nonsense scientifically, and was just made up out of whole cloth by Beck. (Even Venus, with a 90 bar CO2 atmosphere and being closer to the Sun is only 730K, and even if you took away the clouds and threw in another 90 bars of evaporated ocean you don’t get much higher than a few thousand degrees) Awful.
I think the only way we are ever going to stamp out such nonsense is if there get to be charismatic media personalities that know the science needed to shoot down such nonsense, but also know how to present it in an engaging and entertaining way that makes people sit up and take notice. We also need politicians with similar abilities. We need to keep the discussion on a level of sound science, sure, but we need people who can make Beck look as ridiculous as he really is. Meanwhile, maybe it would help if people wrote to Beck, to CNN and to Premiere Radio Networks (which carries his radio show) to let them know how out of line he is. The relevant email addresses can be found in the MediaWatch link above –raypierre]
I would reply to Isaac Held by saying what Wayne Davidson said, with the addition that one should be able to walk and chew gum at the same time. In practice this means making a value judgement as to who is playing which game, but so be it. The denialists have set the rules for any interchange and there is no reason to apologize to them for anything, indeed, experience has shown that it is dangerous to do so.
In reading Isaac Held’s post, the thought came to me that sea surface temperature might be a simple and available metric, but that more sophisticated measures might be needed to advance the argument, for example one which quantified the amount of heat energy available (perhaps in spirit close to some ideas that Roger Pielke Sr. is advancing). The issue then becomes whether such parameters can be reconstructed for a long enough period from data we currently have.