By: Dr. Jeff Masters , 12:33 PM GMT on July 24, 2007

The July 2007 issue of Scientific American has an article called "Warmer Oceans, Stronger Hurricanes" (referred to as "Warmer Water, SUPER HURRICANES" on the cover). The article is written by Dr. Kevin E. Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research, and a lead author on the landmark 2007 climate report issued by the UN's Intergovernmental Panel on Climate Change (IPCC). The article makes the case that "evidence is mounting that global warming enhances a cyclone's damaging winds and flooding rains." The article presents some solid evidence to substantiate that point of view, which I will share below. However, I was disappointed in the general tone of the piece, which was over-hyped and did not paint an objective view of the current scientific thinking on the global warming/hurricane issue.

The hype
First off, the reader is hit with a dramatic full-page artist's depiction of the global super-hurricane of the future--a massive 5000-mile diameter Caribbean storm the size of North America. The storm's 200-mile eye is wider than the Florida Peninsula! Whoa, I said when looking at the whopper "SciAmicane". No doubt many readers perusing the magazine, trying to decide whether to buy it, had the same reaction and plunked down their $5 to read about this grim threat. OK, lets talk reality here. The largest tropical cyclone on record, Supertyphoon Tip of 1979, had a diameter of 1380 miles--less than one third the size of the SciAmicane. A storm like the SciAmicane cannot physically exist on Earth unless the oceans were to super-heat to about 122°F (50°C). Only an asteroid impact or similar calamity could create such a hypercane. Even the most extreme global warming scenarios do not heat the oceans to 122°, so the SciAmicane is there to sell magazines, not to illustrate what global warming might do to hurricanes.

Figure 1. Comparison of sizes: the Earth, the largest tropical cyclone on record (Supertyphoon Tip of 1979, 1380 miles in diameter), and the recently discovered hurricane-like vortex on Saturn (the Saturnicane). The "SciAmicane" is about the same size as the Saturnicane--5000 miles across.

The article also calls attention to 2004, when "an unprecedented four hurricanes hit Florida, and 10 typhoons made landfall in Japan". I've erroneously made this statement, too, but the truth is that Japan was hit by only four typhoons in 2004. Ten tropical cyclones that were of typhoon strength at some point during their life did hit, yes, but six of these had decayed to tropical storm or tropical depression strength by the time they hit Japan. The article then refers to a "consensus explanation" emerging to explain recent hurricane activity patterns, and "that explanation forebodes meteorological trouble over the long term." I'd say that the issue is still very much under dispute. In fact, the consensus statement on hurricanes and climate change adopted by the World Meteorological Organization in December 2006, in response to the recommendations of a panel of 125 hurricane researchers was thus: "Though there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date, no firm conclusion can be made on this point." Trenberth's article gives a list of four publications to read in the "more to explore" section, but none of these include the recent articles that call into question the strength of the global warming/stronger hurricane connection. (I apologize for not reviewing the many excellent articles that have appeared on this subject of late!)

The good science
There's quite a bit of good science in the article, which is worth reading if one keeps in mind its biases. In particular, I like the discussion of how global warming has affected precipitation and atmospheric water vapor. The 0.6°C (1.0°F) rise in Sea Surface Temperatures (SSTs) globally since 1970 has increased water vapor in the atmosphere by 4%, thanks to increased evaporation. This in turn has led to an 8% increase in global precipitation. Trenberth makes the point that no given hurricane can be blamed on global warming, but one can say 8% of a given storm's rainfall is due to global warming. There's also a nice discussion about how weaker than normal trade winds over the tropical Atlantic in 2005 caused less evaporational cooling than normal, allowing the ocean to heat to record temperatures. Finally, the conclusion of the article is one I certainly agree with:

We would all be wise to plan for more extreme hurricane threats.

Both theory and computer models predict a 3-5% increase in hurricane winds per degree C increase in tropical SSTs, and there is concern that the actual increase may be much more than this.

Jeff Masters

For a technical treatment of hypercanes, see Dr. Kerry Emanuel's paper, Hypercanes: a possible link in global extinction scenarios.

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2291. MrNiceville
3:26 PM GMT on July 26, 2007
Thanks, SW.

Good info - agree on the GOM blob - 20kts to 25kts shear, correct?
2288. CaicosRetiredSailor
10:47 AM EDT on July 26, 2007
To read:

WU members discuss evacuation

A compilation of comments WU members left on this Blog concerning evacuation in a more accessible form.
SEE: Link

I have copied these comments, (over 120 comments by about 40 WU members)and it is my first WU blog entry.

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2287. MrNiceville
2:50 PM GMT on July 26, 2007
man - these crickets sure are loud...
2286. MrNiceville
2:29 PM GMT on July 26, 2007
finally at the office - these soccer camps are gonna kill me!

It looks like the convection is deepening in the GOM, but there's 20 - 25kts of shear over it. Hard to make a case for development...

The winds at all levels head N(so are they northerly or southerly?) to NE, so I just can't buy the NW movement - that L is too far west at the moment...

As to rules, I checked in the rear view mirror, guygee - no warts on my nose or face... (grin)

(Edit) Oh yeah - almost forgot - NEW BLOG!
2285. IKE
9:15 AM CDT on July 26, 2007
Member Since: June 9, 2005 Posts: 23 Comments: 37995
2284. moonlightcowboy
2:08 PM GMT on July 26, 2007
LOL, guygee!

For rules...I like an old tune by Tanya Tucker that has a line it..."There's a tree out in the backyard, that never has been broken by the wind...cause it was strong enough to bend!"
Member Since: July 9, 2006 Posts: 184 Comments: 29641
2283. guygee
2:02 PM GMT on July 26, 2007
Posted By: guygee at 12:58 PM GMT on July 26, 2007.
...if you quote me and respond with LOL, without offering any countering evidence or reasoning, then yes, you are a troll. It is not my rule, it is a fallacious argument under the Rules of Informal Logic. It is an Ad Hominem attack. ...
I wish I had never written this, LOL.
I forgot that rules are made to be broken, LOL.
It is the sacred right of every American, it is the American Way! LOL!
(just procrastinating while trying to decide which chore to tackle first, LOL).
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2282. sonofagunn
2:05 PM GMT on July 26, 2007
I guess shear *was* favorable when I posted that link, but it's just been updated with the latest map which shows it less favorable now...
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2281. moonlightcowboy
2:05 PM GMT on July 26, 2007
sonofagun, I see 20-30 kts of upper shear in the GOM in the cimss.
Member Since: July 9, 2006 Posts: 184 Comments: 29641
2280. weathers4me
1:49 PM GMT on July 26, 2007
Are the steering currents in the GOM pushing all that convection into TX still?
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2279. quante
1:44 PM GMT on July 26, 2007
Anyone have a link testing the accuracy of long range forecasts to actual outcome in predicting formation and location of tropical system? In my wholely unscientific experience they are almost never right past 2 days.
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2278. sonofagunn
1:58 PM GMT on July 26, 2007
CIMSS says shear is favorable in the Western GOM.
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2277. Drakoen
1:57 PM GMT on July 26, 2007
TCC if you looked at the cyclone phase diagram its only 2 days...
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2270. amd
1:38 PM GMT on July 26, 2007
It seems that the slow start to the hurricane season as caused some to once again question the notion of global warming.

Tempest In A Teapot


Posted 7/25/2007

Global Warming: A private firm's downgrade of its hurricane forecast raises an obvious question: If scientists can't get near-future projections in a limited area right, how can they predict the climate decades from now?

Related Topics: Global Warming

A reasonable response is: They can't. But the global warming climate of fear did not blow in on the soft breezes of reason, but by the storm winds of emotion.

Forecaster WSI Corp. said Tuesday that the season ending Nov. 30 will bring 14 named storms, six of which will grow into hurricanes, three of them major. WSI's initial forecast was for 15 named storms, eight hurricanes and four majors.

Why the change? "Because," said WSI forecaster Todd Crawford, "ocean temperatures have not yet rebounded from the significant drop in late spring."

Could it be that the 2007 hurricane season is turning out to be as overrated as 2006? Remember last year's predictions that we were in for a brutal spell of storms? It had been quiet, they said, and we were due for a series of Katrina-like hurricanes. But as we wrote last November, as the much-dreaded '06 season whimpered to a close, the storm year came in like a lamb and went out the same way.

For years, the Greenshirts have told us that emissions of carbon dioxide resulting from man's addiction to fossil fuel-based energy are turning the planet into a sweltering hothouse. The United Nations' Intergovernmental Panel On Climate Change has projected a temperature increase of 2 to 11.5 degrees Fahrenheit for the 21st century due to the greenhouse effect.

As a result, alarmists say, ice caps will melt, glaciers will thaw and sea levels will rise as much as 20 feet, causing floods and death in low-lying areas. Storms are also predicted to increase in both frequency and intensity.

To prevent this coming Category 5 cataclysm, we're supposed to shell out trillions of dollars and gladly adopt Spartan lifestyles. Instead of trying, as their grandparents did, to see how many bodies they can squeeze into a telephone booth, today's college kids are expected to see how many they can get in a Prius.

Yet the fact remains: The local weatherman can't forecast more than about 10 days out, and neither can the experts tell us how warm, or cool, the planet is going to be in 2100, 2075 or even 2050.

Even short-term predictions have been off. James Hansen, NASA scientist, predicted a 0.45-degree Celsius (0.81-degree Fahrenheit) rise in global temperature from 1988 to 1997. But in reality (a place environmental activists rarely visit) the increase was a mere 0.11-degree Celsius.

We hope no one in Hansen's neighborhood relies on him to tell them when it's going to rain or when they'll need a coat and hat.

Setting aside the hubristic notion that alarmists know what the right temperature is, too many other factors besides the greenhouse effect influence climate for them to declare they know exactly, or even approximately, what's coming. Solar activity, for instance, is among the most powerful, as are the El Nino and La Nina phenomena.

We also question the concept of a "global" temperature. How could such a thing be measured when weather stations dot rather than blanket the Earth? Danish physicist Bjarne Andresen, a professor at the University of Copenhagen, made sense earlier this year when he said it's "impossible to talk about a single temperature for something as complicated as the climate of Earth.

"A temperature can be defined only for a homogeneous system (and) climate is not governed by a single temperature," he said. "Rather, differences of temperatures drive the processes and create the storms, sea currents, thunder, etc. , which make up the climate."

The formula for a climate of fear, though, requires nothing more than a lot of thunder and a bit of heat generated by political activists.
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2267. Drakoen
1:34 PM GMT on July 26, 2007
lol jp.
whats with the italics?
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2264. Drakoen
1:28 PM GMT on July 26, 2007
we have to keep track of it from the EUMETSAT for now.
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2263. ryang
9:28 AM AST on July 26, 2007
SAL is fairly weak and moving west, and the wave isn't on water yet.
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2262. weatherguy03
9:28 AM EDT on July 26, 2007
Hey I dont take you to the woodshed GR!..LOL
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2261. ryang
9:25 AM AST on July 26, 2007
It looks healthy and fairly strong/large...

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2260. weatherguy03
9:26 AM EDT on July 26, 2007
03 - for those of us who are Wx amateurs, what's a line of convergence?

Winds of opposite directions conveging to produce T-storms. SW winds ahead of that trough, winds from the South coming out of S to SE. This will cause lift and produce T-storms, especially over the warm GOM.
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2259. GetReal
1:26 PM GMT on July 26, 2007
OK thanks for the clarification (lesson) Bob...
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2258. Drakoen
1:26 PM GMT on July 26, 2007
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2257. weatherguy03
9:24 AM EDT on July 26, 2007
GR. It would be very hard GR, epsecially the way the Upper Level winds are right now. And something I mentioned yesterday with this area. Its moving at a good clip to the NNW, while the trough isnt going anywhere. Its in a no win situation.
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2256. drusierDMD
1:16 PM GMT on July 26, 2007
an additional frame can be seen on the loop 12Z (that you cant see one the single image 6Z)

probably will be fixed before any1 can confirm

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2255. TropicalNonsense
1:20 PM GMT on July 26, 2007
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2254. Drakoen
1:19 PM GMT on July 26, 2007
According to the GFS we should see some action on Saturday.
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2252. GetReal
1:14 PM GMT on July 26, 2007
Posted By: weatherguy03 at 1:07 PM GMT on July 26, 2007.

those t-storms have blown up due to convergence. You can see the convergence line move north and then there is the blowup of storms. Thats all it is, just like yesterday.

Bob I know that I may regret this, and I'm sure you will take me out to the WU wood shed, but here it goes... Bob so what you are saying is that it is impossible, or highly unlikely, for a low pressure area to spinup out of a convergence zone?
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2251. Drakoen
1:17 PM GMT on July 26, 2007
yea ryang its very large and it probably what the GFS is picking up on.
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2250. ryang
9:16 AM AST on July 26, 2007
The GFS model forecasts that this wave will be a strong tropical cyclone near 15 North, 48 West by next Thursday.
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2248. ryang
9:14 AM AST on July 26, 2007
Guys, the next wave about to exit, is a real threat.
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2247. Drakoen
1:14 PM GMT on July 26, 2007
I see. I would think because of the time frame that it would be associated with the wave coming of Africa. Its fairly large in size. we will see.
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2246. hurricane23
09:11 EDT le 26 juillet 2007
Posted By: Drakoen at 09:09 EDT le 26 juillet 2007.

morning everyone. The GFS still forecasting development?

LOL look up in the blog...I posted a pic for some entertainment.
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2245. guygee
1:07 PM GMT on July 26, 2007
MrNiceville- Thanks for clarifying. Civility seems to be an ancient art these days, it is really a step beyond logical rules and would make the blog much more enjoyable if everyone practiced it. I am afraid sometimes I have lost the art and come off stone cold, but that is not my intent.

LOL, I guess I can be a bit humor-impaired at times too. I wouldn't presume to make up personal rules for this blog, but Roberts Rules of Order is probably a step above the simple rules of logic in helping people get along.

BBL, have a good one!
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2244. IKE
8:12 AM CDT on July 26, 2007
Rain headed for New Orleans....

Member Since: June 9, 2005 Posts: 23 Comments: 37995
2243. Drakoen
1:11 PM GMT on July 26, 2007
yea hurricane23 thats the problem when its gets on water it they loose some of the convection.
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2242. hurricane23
09:07 EDT le 26 juillet 2007
Lets keep an eye on the wave about to exit africa as the GFS is picking up on it and really cranking it for the first time this year.As we move into august next week our chances for development continues to go up.

Lets see if it can maintains its thunderstorm activity once it moves of the african coast.
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2241. MrNiceville
1:09 PM GMT on July 26, 2007
03 - for those of us who are Wx amateurs, what's a line of convergence?

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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