Guest post by Kerry Emanuel
In the past 16 months, two exceptionally intense tropical cyclones, Haiyan and Pam, have struck the western Pacific with devastating effect. Haiyan may have had the highest wind speeds of any tropical cyclone on record, but we will never know for sure because we do a poor job estimating the intensity of storms that are not surveyed by aircraft. (Currently, only North Atlantic tropical cyclones are routinely reconnoitered by aircraft, and only if they threaten populated regions within a few days.) Pam’s analyzed intensity puts it within 10 knots of the most intense storms on record in the South Pacific, but here again this is within the error bars of satellite-derived intensity estimates.
Pam’s high intensity and terrible impact on Vanuatu have invariably raised the question of the possible effect of global warming on its characteristics. For example, Vanuatu’s President Baldwin Lonsdale blamed the disaster partly on climate change. Just as predictable is the backlash to the effect that no single event can be attributed to climate variations of any kind. What can we say about the effects of climate change on South Pacific tropical cyclones?
We can begin by looking at the record of tropical cyclones in that region. Unfortunately, for the reasons discussed above, these records are poor and those that exist only go back to about 1980, though there are longer records of storms making landfall in Australia. Perhaps the best existing analysis of South Pacific tropical cyclones is that of Kossin et al. (2013), who homogenized the satellite data record from 1982 to 2009 to create a temporally consistent record, and compared that to the problematic historical data base of storms over the world. While the historical data in the South Pacific region show a highly significant upward trend in the incidence of high intensity events, the satellite-based record shows a less prominent and significant trend of 2.5 m/s per decade with a p value of 0.09. Thus there is some evidence of a trend toward higher intensity of high category tropical cyclones in the South Pacific over the period 1982-2009, but it is not conclusive and in any event spans a limited time interval.
We can also look at trends in important environmental factors that are known to influence tropical cyclones. The usual suspect among these is sea surface temperature (SST) and there has been much talk about the elevated SST’s in the region where Pam developed. But SST by itself is not the main factor in the existing theory for the upper bound on tropical cyclone intensity, known as the potential intensity; instead, the potential intensity depends more nearly in the difference between SST and a measure of the bulk temperature of the troposphere as well as the temperature of the tropopause. An expression of the potential intensity, measured in maximum possible wind speed, is
where Vp is the potential maximum wind speed, Ts is the surface temperature, Tt is the tropopause temperature, hs* is the saturation moist static energy of the sea surface, and h* is the saturation moist static energy of the free troposphere, which is nearly uniform with height if the lapse rate is moist adiabatic. In the deep tropics, temperature is nearly uniform on pressure surfaces because there is not enough Coriolis acceleration to balance strong pressure gradients, thus h*, which is just a function of pressure and temperature, is horizontally as well as vertically uniform in the free troposphere. Therefore, the potential intensity depends mostly on variations of SST (which controls hs*) for climate variations that do not affect the mean temperature of the troposphere. But global warming very definitely does affect the temperature of the tropical free troposphere, so it is not possible to conclude, as alas many have, that increasing SST per se means increasing tropical cyclone intensity (though it usually does signify more TC-related rain).
It is not difficult to calculate the actual potential intensity from SST and atmospheric soundings, and this can be done as well for reanalysis and global model data sets. The map below shows the potential intensity at 12 GMT on 7 March, 2015, calculated from the NCEP operational analysis at that time. The track of PAM is superimposed in blue.
Pam traversed a region of potential intensities around 75 m/s, consistent with the storm’s estimated peak intensity. These values are not unusual in this region, but for the past few decades they have been increasing if the reanalyses are to be believed. I calculated potential intensity trends over the period 1980-2012 using three different reanalysis products: NASA’s MERRA, the European Center’s ERA Interim, and the NCAR/NCEP reanalysis. The MERRA and ERA Interim reanalyses show upward trends of around 2 m/s per decade in the region where Pam formed, while NCEP’s trend is closer to 3 m/s per decade; all these trends have p values less than 0.1. These trends are broadly consistent with the Kossin et al. (2013) trend of 2.5 m/s per decade in the observed intensity of high category tropical cyclones in this region.
Thus the weight of evidence points to increasing potential intensity in the region where Pam developed, and consistent with this, increasing intensity of the highest category storms based on satellite-derived measurements. But to what do we attribute such increases? The roughly thirty year period over which we have reliable reanalyses and satellite measurements is too short to rule out the influence of natural climate variability, such as the Pacific Decadal Oscillation. We can at least check to see what kinds of trends climate models produce. I looked at eight CMIP 5 models whose output I had ready access to and calculated linear trends of potential intensity over the period 2006-2100 under the RCP 8.5 emissions pathway. The eight models were the NCAR CCSM4, a super-parameterized version of the same, referred to as SP-CAM, The GFDL CM3, the UKMO HADGEM-ES, the IPSL CM5A-LR, the Max Planck MPI-ESM-MR, the CCSR/NIES/JAMEST MIROC5, and the Meteorological Research Institute’s MRI-CGCM3. Of these, two models showed insignificant trends in the region in which Pam developed, and the rest showed positive trends averaging around 0.5 m/s per decade, considerably less than the observed trend over the last 30 years. The largest trend was produced by the GFDL model, whose global trend distribution is shown below. (White areas represent p values less than 0.1., and the units are m/s per decade.)
It is interesting that the largest increases are at the polar peripheries of the tropics, indicating a general expansion of the regions that are thermodynamically favorable for tropical cyclone development; this general feature is present in most of the model potential intensity trends as well as the reanalysis trends over the past 30 years, and may be behind the poleward migration of the latitudes at which observed tropical cyclones reach their peak intensity, as documented by Kossin et al. (2014).
The disparity between the reanalysis potential intensity trends over the past 30 years and the projected trends over this century suggests either that most of the observed increase in potential intensity (and actual intensity of high category storms) is due to natural variability, that decreasing anthropogenic aerosol loading over that period may have played a role, or that the model projections are too conservative. Yet the projected increase is not insignificant, amounting to about 5 m/s over 100 years. Note from the figure above that there are somewhat larger increases elsewhere, particularly in the northern hemisphere.
All of this is consistent with the strengthening consensus that the frequency of high category tropical cyclones should increase as the planet warms (Knutson et al., 2010). Basic theory and a variety of numerical simulations support this, as well as the projection that tropical cyclones should produce substantially more rain, owing to the increased moisture content of the tropical atmosphere. This is important because most destruction and loss of life are caused by high category storms and their attendant storm surges, and by freshwater flooding from torrential rains. Most of the disagreement in the literature on tropical cyclone projections concerns the incidence of weak storms, but these are usually far less consequential in spite of being more numerous.
Besides the oft-discussed issues of TC frequency and intensity, changes in genesis locations and tracks are potentially very important, as are the diameters of TCs, which affect the area covered by strong winds and which greatly affect the magnitudes of storm surges. In the present climate, the diameter of storms, as measured by the radius at which their circular wind component becomes indistinguishable from environmental winds, appears to be log normally distributed, with a mean around 420 km (Chavas and Emanuel, 2010). There is some indication from modeling studies that the size of the dangerous inner core scales with the potential intensity divided by the Coriolis parameter (Khairoutdinov and Emanuel, 2014). If this turns out to be true in nature, then storm inner core dimensions should increase over time.
While Pam and Haiyan, as well as other recent tropical cyclone disasters, cannot be uniquely pinned on global warming, they have no doubt been influenced by natural and anthropogenic climate change and they do remind us of our continuing vulnerability to such storms. Destructive TCs in any one place tend to be generational…enough time for people to forget them and go back to risky behavior, including over-development of coastal regions. We adapt more successfully to the more frequent events which are always in the back of our minds (and often in the front). But this human adaptation time scale may be longer than the time over which climate change affects storms, so that comparatively small changes in the frequency of generational events can have large social consequences. When a 100-year event becomes a 50-year event, it may take a few destructive hits before we adapt to the new reality. This is of particular concern with tropical cyclones, where the application of existing damage models to projected changes in tropical cyclone activity predict large increases in damage, as documented, for example, in the recent Risky Business report commissioned by Michael Bloomberg, Hank Paulson, and Thomas Steyer*.
Now if only we could better measure tropical cyclones to record how they may change in coming years.
_________
* [Update, 1pm ET] It has been pointed out that in my reference to the Risky Business report, I might have mentioned that I contributed synthetic hurricane event sets that were used by Risk Management Solutions, Inc., to estimate damages from tropical cyclones.
References
Chavas, D. R., and K. A. Emanuel, 2010: A QuickSCAT climatology of tropical cyclone size. Geophys. Res. Lett., 37. 10.1029/2010GL044558.
Khairoutdinov, M. F., and K. Emanuel, 2014: Rotating radiative-convective equilibrium simulated by a cloud-resolving model. J. Adv. Model. Earth Sys., 5, In press.
Knutson, T. R., and Coauthors, 2010: Tropical cyclones and climate change. Nature Geosci., 3, 157-163.
Kossin, J. P., T. L. Olander, and K. R. Knapp, 2013: trend analysis with a new global record of tropical cyclone intensity. J. Climate, 26, 9960-9976.
Kossin, J. P., K. A. Emanuel, and G. A. Vecchi, 2014: The poleward migration of the location of tropical cyclone maximum intensity. Nature, 509, 349-352.
Kerry Emanuel is professor of atmospheric science at MIT and one of the world’s leading tropical storm experts.
It strikes me that while the trend may still be of low significance, the exceptional may be more attributable in the same manner that extreme heat waves find strong attribution through their new occurrence.
Thanks for this super timely post.
Could you elaborate on the following sentence in your piece, hopefully with an example.
“There is some indication from modeling studies that the size of the dangerous inner core scales with the potential intensity divided by the Coriolis parameter”.
@Chris Dudley, yes, and a quantile regression may be able to help with that.
Thanks. A timely analysis, and a nice, succinct overview.
Another edge effect which may provide attribution sensitivity would be to look at seasons. How does November change, for example? Does the region over which storms may occur expand dramatically with warming?
If you are 19 years old, there hasn’t been any GW since you turned 18. We need to make disaster history a mandatory course in high school.
For the Central and North American region, many hurricane experts think there is a loose fitting 30 year cycle (i.e., 30 years of higher intensity followed by 30 years of lower intensity), based upon data going back to 1870. I have a graph of this from a local NOAA office presentation. Sorry for not citing anything here. If such a long cycle existed for the South Pacific, it appears we would not know due to lack of data.
I wonder if you also looked at the depth of very warm water over which the TCs move as a contributing factor.
In response to Mauri Pelto: We have modelled hurricanes in limited domains that are in statistical equilibrium with surface fluxes and radiation. These domains have boundary conditions that are horizontally uniform, so they produce a regular pattern of TCs that we sometimes refer to as “TC World”. The number, size, and strength of such simulated TCs all obey nice scaling relations. But it is a stretch to go from these to the real world. You can read more about it here: http://onlinelibrary.wiley.com/doi/10.1002/2013MS000253/full .
No GW for the last year? I think that really is far too short a period to make such strong a claim. If, by chance, you meant no GW for the past 18 years, then that is wrong. Maybe we should make science a mandatory course in high school :-)
Y’know, ATTP (#11), I know you were being ironic, but I’ve seen people recommending a half-semester or so of statistics in high school. I think it’d do a lot to improve the numeracy of the general public, since it’s one of the big gaps in the public’s understanding that lets propaganda get through. “Lying with statistics” is a very real thing.
In 1975 i sailed across the image shown, ( it was then the New Hebrides) and though the weather was idyllic, there was a constant 12 to 15 foot swell coming up from the Big South .
This is not a sea state you want to see amplified by the passage of a storm like this, at sea or on any windward coast.
I wonder if Tisman Plantation is still there ?
#7–Ed, what on Earth are you on about? Did you miss the whole ‘faux pause’ thread?
Windchaser,
I’ve realised that my comment has ended up well below where I intended it to be. It was intended to be a response to #7.
I don’t disagree with you. I think there are many things that could be done to improve the numeracy of the general public.
Thank you for an exceptionally good post.
Hi Kerry,
Thanks for the post. Re your potential intensity map– Have you looked at the CMIP5 historical simulations as a gauge for what “should have” happened given best estimates of historical forcings? Or would we expect too much variation among the ensemble members? I guess I wonder if it’s fair to start thinking about the cause for discrepancies with reanalysis based on what you’ve done here.
A follow-up question related to where we might lose contact between historical and future is the disproportionate role of aerosols on the asymmetries in climate forcing. I have in mind the idealized simulations of Tim Merlis, for instance, on the role of ITCZ shifts as it relates to genesis locations.
Thank you for showing an index of hurricane strength that includes something other than sea surface temperatures. Sea surface temperature is obviously not the only important measure.
The Uncomfortable Truth
34 years of science agreeing to be 99% certain we need to SAVE THE PLANET makes another 34 years of climate action FAILURE 100% certain.
Deny that.
If the eye looks a little ragged, blame the erupting volcano on Tanna — an impromptu sulfate tracer experiment on a scale the EPA might balk at sanctioning.
#16–Meme Mine, the master or mistress of the unparsable sentence, has sneaked it past the Cerberus of the Borehole.
Much appreciated post, thanks. I’m looking for enlightenment on this part of the OP:
But what do we expect to happen? When there’s reason to expect tropical temperature trends to be amplified aloft, how come we nevertheless expect more intense tropical cyclones?
Pointers welcome. I’m an interested layman who does try to read the scientific literature, but having looked at some (including Emanuel’s seminal papers) I realize I could do with a dumbed-down version.
Hello Chris: That is a good idea and if I can eek out some time I will look. Per watt per meter squared of radiative forcing, shortwave forcing is about twice as effective in changing potential intensity as is longwave forcing (see my paper with Adam Sobel in JAMES in 2013). Thus aerosol forcing is very important. The the wide spread in aerosol forcing in the models is bound to produce a wide spread of potential intensity trends over the late 20th century. Regards, Kerry
mememine, Hmm, it would be easier to affirm or deny your sentence if I could parse the word salad you’ve posted.
Dear Kerry,
Thanks for an interesting analysis. In response to your original question “What can we say about the effects of climate change on South Pacific tropical cyclones?”, I’d note that another perspective on the impact of Pam (or many other cyclones) is simply sea level rise.
Even without changing intensity or frequency of storms, the impact of associated storm surges increases with increasing sea levels. Precise quantitative attribution to climate change is complex (for instance due to diversity among the islands in terms of relative sea level rise, and often short tidal gauge records), but as a pattern it’s definitely an important factor in increasing disaster risk in these areas (and an additional reason to proactively manage exposure and vulnerability).
Kind regards,
Maarten
Folks, mememine is a known troll, occasionally prolific in his idiocy on various threads. Please avoid feeding him.
CM: The saturation moist static energy, h*, depends on temperature and pressure but it is not the same thing as temperature. In particular, when the tropical climate warms (for whatever reason) the change in h* tends to be constant in height, and this indeed corresponds to a temperature change that increases with height. What is most important is how the difference, h_0*-h* changes…both quantities increase with warming, and it turns out that the difference also increases, but more slowly. I hope I have not simply added more to the confusion…..
http://members.westnet.com.au/jonas1/HurricanesKlotzbachAndGray20080805.pdf
“from 1945-1969 when the globe was undergoing a weak cooling trend, the Atlantic basin experienced 80 major (Cat 3-4-5) hurricanes and 201 major hurricane days. By contrast, in a similar 25-year period from 1970-1994 when the globe was undergoing a general warming trend, there were only 38 major hurricanes (48% as many) and 63 major hurricane days (31% as many) (Figure 15)“.
A Warming world is a less stormy world?
Adam G: You cannot conclude that just from looking at a basin which has less than 15% of the total global tropical cyclone activity, and also selecting groups of years that coincide exactly with the positive and negative Atlantic Multi-decadal Oscillation phases, which would dominate over any AGW trend in this basin if it exists.
for Adam Gallon — that’s argued, but not established.
See: http://blogs.nature.com/news/2008/04/update_storm_over_globalwarmin.html
Also see the citing papers
http://scholar.google.com/scholar?q=klotzbach+gray+2008+hurricane
And, e.g., consider the data sources are rough at best for earlier years:
http://www.aoml.noaa.gov/hrd/hurdat/A_Reanalysis_of_the_1944-1953_Atlantic_Hurricane_Seasons_-_The_First_Decade_of_Aircraft_Reconnaissance.pdf
PS for Adam Gallon, if you put Klotzbach Gray into the site search box (upper right) you’ll find much discussion of that whole area going back well before that one 2008 paper you mention. There’s much to read.
I’ve always thought it ‘obvious’ that hurricane intensity would be linked to SSTs due to latent heat energy considerations, and not to differences between SST and upper atmosphere temperature. The basic thought is that moisture content is non-linear with higher slope at higher temp, so that if the surface and upper atmosphere would warm at roughly the same rate the gain in latent energy at the surface would be faster than the gain in latent energy in the troposphere, or in terms of your equation hs* – h* would increase as hs* grows faster than h*?
People might like to take a look at this:
http://www.ssec.wisc.edu/data/geo/index.php?satellite=west&channel=wv&coverage=fd&file=gif&imgoranim=8&anim_method=flash
Kerry Emanuel @27: That was very helpful. Now I know I was looking at it the wrong way. Thanks.
A bit OT but…
Thanks, Professor Emmanuel, for your part in the Annenberg series “The Habitable Planet”. That’s where I first encountered your work. You gave one of the most substantive interviews for a “general” audience that I have ever seen on TV. It was so full of ideas that it took me several viewings to take it all in. It advanced my understanding of some basic climate physics AND helped me understand a bit about your topic here. (I’m a chemist, not a climate scientist.) Well done. We need more science education videos like “The Habitable Planet”!
Apologies for misspelling your name. ;=(
Michael Hauber: “I’ve always thought it ‘obvious’ that hurricane intensity would be linked to SSTs…”
Very good observation the heat engine can do more work with higher vapor concentrations. The assumption that the extra work does not get cancelled by an equivalent degradation of the temperature gradient, or other feedbacks, should to be tested.
Be sure to check out…………………
Incredible before/after pictures from pilot William Dyer #TCPam #CyclonePam #Vanuatu.
https://twitter.com/SamBolitho/status/578306494363348992/photo/1
??? Just typographic
Pam’s high intensity and terrible impact on Vanuatu have invariably raised the question
-did you mean-
Pam’s high intensity and terrible impact on Vanuatu have inevitably raised the question
The global ACE shows very little overall trend.
“There is no evidence of a systematic increasing or decreasing trend in ACE for the years 1970-2012.”
http://www.wunderground.com/hurricane/accumulated_cyclone_energy.asp?basin=gl
In fact since 1990 it has been decreasing. One could just as easily point to this trend and assert it is “significant”. The fact that certain basins are increasing while others decrease is exactly what one would expect from sporadic extreme events using a low number of chaotic data points.
In order to overcome the noise here, you must increase the numbers through either using global datasets or longer trends.
As shown above when using global datasets there appears to be no overall trend either way. When using longer datasets in the northern hemisphere such as US landfalls over the past century, no trend emerges in the second half of last century. There are many other measures that show either conflicting data or no trends apparent.
What bothers me the most is the moving target of what one considers “significant”. After the very active years in 2004-2005 (Katrina, 3 major landfalls in FL) we were given the lecture of “more frequent, more intense”, the “new normal”.
Update: We are now in year 9 and counting of no major Cat3+ landfalls in the US, by far the longest period on record between landfalls. Less frequent, less intense. Some of the quietest years on record have occurred recently. What are we talking about? Pam, Haiyan, and Sandy. Not the overall numbers.
Some may dismiss this record on the lack of US landfalls. What I challenge you to consider is what would happen if we just finished a decade setting a record for the must US landfalls of Cat3+ hurricanes? Would this not be considered “significant”? But a record lack of landfalls is apparently dismissed as unimportant and unrelated to climate change.
Why do I care? Guess what happened to wind insurance rates in FL after 2005 when they stopped using historical records and started using estimates by climate models. 30% cost increases. Emanuel was one of those that provided models. Read all about it in the 2011 Pulitzer Prize winning series from the Sarasota Herald Tribune:
Florida insurers rely on dubious storm model
http://www.heraldtribune.com/article/20101114/article/11141026?p=1&tc=pg
“The rock star in the room was Kerry Emanuel, the oracle of climate change from the Massachusetts Institute of Technology. Just two weeks before Katrina, one of the world’s leading scientific journals had published Emanuel’s concise but frightening paper claiming humanity had changed the weather and doubled the damage potential of cyclones worldwide.”
I hold no grievance against Kerry Emanuel. He is doing his job and typically is straight up in other articles I have seen him quoted. The more they let him talk, the more reasonable he sounds.
What I find surprising is how little he is challenged here when there is obvious counter factual data to any future estimates of increases in cyclones.
…and finally…a question (ha ha).
What do you consider the most meaningful observational measurements we should be tracking over the next 10 years?
TS 40,
Significance is not something one “feels.” It is something that can be measured statistically. When a scientist says an effect was found to be significant, he/she is not using the word as a loose synonym for “important.” Significance is a number.
For example, if you have a regression line (least-squares fit) of some variable over time, there is a “Student’s t-statistic” associated with the slope of the line. If the absolute value of t is > 2, it is “significant at the 95% confidence level.” This means the chance of the variable being unrelated to time, and the relationship seen in the least-squares plot being due to sampling error, is 5% or less.
> significant?
Depends. What’s your prior assumption?
Search for “tempestology” and you’ll find papers trying to assess like this:
http://www.geosociety.org/news/pr/13-81.htm
The geologic legacy of Hurricane Irene: Implications for the fidelity of the paleo-storm record
Scott Hippensteel et al., Dept. of Geography and Earth Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, USA; shippens@uncc.edu. Pages 4–10; doi: 10.1130/GSATG184A.1, http://www.geosociety.org/gsatoday/.
Very annoyed with time wasters.
“For example, Vanuatu’s President Baldwin Lonsdale blamed the disaster partly on climate change.”
That is false. It is no different than what denier media does to SPIN what is actually said by people and reported in the IPCC Reports and Science papers.
This is what he really said: “Climate change is contributing to the disaster in Vanuatu.”
That is no different than what the Fifth IPPC Reports and underlying Science Papers have said. How could “climate change” NOT contribute to a cyclone weather event, when everything about that weather event is effected by the prevailing CLIMATE which has been scientifically proven to have changed and is continuing to change? Impossible.
The President of Vanuatu was simply articulating the KNOWN SCIENTIFIC Findings of Claime Scientists. If he is worng, if he has oversteeped the mark, then so have all the Climate Scientists too .. when they say in the IPCC that “Climate Change is contributing to more severe weather events.”
I repeat all he said was “Climate change is contributing to the disaster in Vanuatu.”
Some audio of the Presidents press conference in Japan
http://www.radioaustralia.net.au/international/radio/program/pacific-beat/emotional-vanuatu-president-describes-cyclone-pam-affects/1425665
3:30 mins he speaks about the World Conference on Disaster Risk Reduction in Sendai, that he was attending. Obviously a focus of that was Climate Change drivers.
He also said: President Lonsdale described Cyclone Pam as a monster that had set back the government and the people of Vanuatu.
“After all the developments that has taken place, all this has been wiped out. So it means that we will have to start anew again”.
Then he says: “We see the level of sea rise, changing weather patterns,”
“This year we have MORE [rain] than every year and for the last couple of weeks, the heavy rain falls throughout Vanuatu and it EXCEEDED what has happened in the past. ”
“This is a very devastating cyclone that has crossed Vanuatu,”
“I term it as a monster. It’s a monster that has hit the republic of Vanuatu,”
Original news report: http://www.abc.net.au/news/2015-03-16/vanuatu-president-breaks-down-describing-cyclone-devastation/6322586
http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/vanuatu/11474167/Vanuatu-president-says-climate-change-contributed-to-Cyclone-Pam.html
http://www.smh.com.au/environment/climate-change/vanuatu-president-begs-world-to-help-rebuild-blames-climate-change-after-cyclone-pam-20150317-1m0oeo.html
Just as the media DISTORTS in the “headings” what he said, so has RealClimate.
—–
So we have Stefan saying:
Pam’s high intensity and terrible impact on Vanuatu have invariably raised the question of the possible effect of global warming on its characteristics.
For example, Vanuatu’s President Baldwin Lonsdale blamed the disaster partly on climate change.
Just as predictable is the backlash to the effect that no single event can be attributed to climate variations of any kind.
What can we say about the effects of climate change on South Pacific tropical cyclones?
THEN STEFAN SAYS EXACTLY WHAT THE PRESIDENT WAS INFERRING IN HIS PRESS CONFERENCE; and what has been repeatedly said already in the IPCC Reports:
“While Pam and Haiyan, as well as other recent tropical cyclone disasters, cannot be uniquely pinned on global warming, they have no doubt been influenced by natural and anthropogenic climate change and they do remind us of our continuing vulnerability to such storms.”
From the very beginning came the denial of sufficient data to draw such conclusions:
— we will never know for sure because we do a poor job estimating the intensity of storms that are not surveyed by aircraft.
— here again this is within the error bars of satellite-derived intensity estimates.
— but it is not conclusive and in any event spans a limited time interval.
— “But global warming very definitely DOES affect the temperature of the tropical free troposphere, so it is not possible to conclude, as alas many have, that increasing SST per se means increasing tropical cyclone intensity (though it usually does signify more TC-related rain).”
— [but sure does NOT suggest a DECREASE of Intensity either, does it Stefan?]
— but for the past few decades they have been increasing IF THE REANALYSES ARE TO BE BELIEVED – [ got anything else that is MORE believable Stefan? ]
— How about THIS : “Thus the weight of evidence points to increasing potential intensity in the region where Pam developed, and consistent with this, increasing intensity of the highest category storms based on satellite-derived measurements”
— How about THIS: “All of this is consistent with the strengthening consensus that the frequency of high category tropical cyclones should increase as the planet warms (Knutson et al., 2010).”
— [ like DOH … The president was therefore correct and within the CLIMATE SCIENCE CONSENSUS, yes Stefan? ]
— “… appears to be log normally distributed, with a mean around 420 km (Chavas and Emanuel, 2010).” Do you know anyone at NASA???
“On March 12 – (391.3 miles/629.7 km) in diameter.” http://www.nasa.gov/content/goddard/pam-southern-pacific-ocean/
Mar 13, 2015 – Super cyclone Pam is passing less than 100 kilometers east of Port-Vila as we write. Our conservative sustained wind speeds estimate is 180 kph, gusts up to 220 kph. The JTWC says 260 kph, gusts up to 320 kph. A horrendous phenomenon. Hell on Earth. Nature gone crazy. – Pam is huge monster. 600 kilometers core diameter. http://xtremeweatherforecast.blogspot.com.au/2015/03/tropical-cyclone-pam-Vanuatu-new-zealand.html
— I calculated potential intensity trends over the period 1980-2012 & The disparity between the reanalysis potential intensity trends over the past 30 years and the projected trends over this century suggests either that most of the observed increase in potential intensity (and actual intensity of high category storms) is due to natural variability,….”
— [IRRELEVANT to 2015 and CAT 5 Cyclone Pam !!! Do you understand this fact Stefan? Use 2015 Data, use Pam specific Data or be silent about these things – you make the situation FAR WORSE not better for the Public and Politician’s UNDERSTANDING and JUDGMENTS. ]
— While Pam and Haiyan, as well as other recent tropical cyclone disasters, cannot be uniquely pinned on global warming, [ WHO HAS EVER CLAIMED THEY WERE STEFAN ? Even Monckton has not been that stupid. ]
AND THEN STEFAN STATES AT THE END:
“Now if only we could better measure tropical cyclones to record how they may change in coming years.”
What a waste of time and energy. Some people seem to enjoy the sounds of their own voices, more than taking real effective steps, profound media releases or REAL Action to stop AGW/CC…… endless navel gazing attention seeking articles instead?
THis is NOT educating THE PUBLIC or POLICY MAKERS in any meaningful way .. please keep this kind of stuff in the University lecture rooms where it belongs.
Please do learn how to communicate better, put your time and resources to better use, and focus on SCIENTIST ACTIONS to create Political ACTION to remove the Cause of AGW/CC .. not on this naval gazing over IRRELEVANT Minutia
— PLEASE, if it isn’t too much trouble?
for Thomas O’ — it’s not that simple.
Read these:
http://scholar.google.com/scholar?as_ylo=2015&q=climate+storm+heat+engine+warming+ocean+atmosphere
and then do the same search with ordinary Google and
look at the variations on the story as it appears on various blogs:
https://www.google.com/search?q=climate+storm+heat+engine+warming+ocean+atmosphere
Many of us can’t get into those “University lecture rooms” — this is the place we come to learn what’s known and being learned about the science.
You know how a heat engine works, and what happens to work output when the cold end of a heat engine gets warmer.
What happens to storms as climate warms up?
It isn’t a simple answer, and size does matter,
It’s interesting. It’s likely important — but are you sure you know how?
(I don’t. That’s part of what I want to learn here.)
Wow, talk about ‘time wasters’! I read through all of Thomas O’s rant, and could get no coherent point except that he was very annoyed for some reason.
If he plans to post here in the future, I would suggest to him to take his own advise: “Please do learn how to communicate better”
(Including to avoid using ALL CAPS!)
#45–Second that. I got about halfway through and decided there was probbly nothing worthwhile reading in the second half.
BPL,
I’m not using significance in the statistical sense. I’m using it in the “what one chooses to highlight” sense. Sorry for the confusion.
I find the entire concept of attempting to partially attribute cyclone power or frequency of specific storms to climate change wanting, in light of the fact that the overall numbers do not appear to demonstrate any trend. When the large numbers aren’t showing a trend, it’s a stretch to say that specific storms are affected.
I get the physics argument. If temperatures were 50C lower then we would certainly have fewer storms. If temperatures were 100C higher we would also have fewer storms as well (ha ha). We only have hurricanes from June to November, so obviously temperature has some affect.
I do not contest the trivial argument that temperature changes must have “some affect”. The question of course is whether it is significant, minimal, or effectively non-existent. After 100 years of warming there isn’t much to discern from multiple different measurements. This would suggest that the next 1C of warming is unlikely to bring significant changes as well. The affect could be highly non-linear, but I don’t think this is what the science is suggesting may happen.
I find it to be arm waving when terms are thrown around that “storms will get stronger” without any estimate of how much stronger (2 mph? 20 mph? 0.2 mph?) or the time frame it is expected to occur in (2 years, 200 years, 20 years?).
#43 Thomas, why are you giving Stefan a hard time? I thought Kerry Emanuel wrote this guest column.
–#47:
– See more at: https://www.realclimate.org/index.php/archives/2015/03/severe-tropical-cyclone-pam-and-climate-change/comment-page-1/?wpmp_tp=1#sthash.WR1hQQkG.dpuf
I really don’t think that follows–and doubly so, if the response is non-linear, as you comment that it could be.
#48 “Thomas, why are you giving Stefan a hard time? I thought Kerry Emanuel wrote this guest column.”
Because Stefan published it. He’s a key member of RC since day one, he is responsible for what he publishes here. Not the author.
[Response: This is wrong. Guest posts are lightly edited for clarity, but they reflect the views of the author, not the person who uploaded the post. – gavin]