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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1491. jamweather
8:14 PM GMT on July 25, 2007
where do you go to monitor buoy in the GOM?
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1490. louisianaboy444
8:11 PM GMT on July 25, 2007
How do you determine if the model is predicting a disturbance or a tropical storm or hurricane?
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1489. Drakoen
8:13 PM GMT on July 25, 2007
whats wrong with the FSU site today? It won't show the latest GFS run in the cyclone phase diagram and its taking longer than usual with the UKMET 12z run. Usually the GFS and the UKMET are the first model run to come out.
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1488. NeverPanic
8:07 PM GMT on July 25, 2007
Just keep an eye on those Floaters..They get em up and runnin soon as their intrest is tweeked. Til then, got a couple of good Doc's to watch.
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1487. tampabayfish
8:10 PM GMT on July 25, 2007
Pressure down to 1014 and falling at the buoy
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1486. Drakoen
8:05 PM GMT on July 25, 2007
lol ok. 850mb (the lower levels). By using the 850mb vorticity you can see what exactly the models are predicting in terms of rotation/cyclogenesis. 700-500 mb is the mid levels. and 250mb is the upper levels. You can use the 250mb vorticity to determine upper level lows.

850-200mb shear shows you how high or low the shear is in the upper levels of the atomsphere.
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1484. IKE
3:04 PM CDT on July 25, 2007
There's 20-30 knots of shear in most of the GOM.

There's around 20 knots out in the Atlantic with that disturbance.
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1483. louisianaboy444
8:02 PM GMT on July 25, 2007
Yeah i'm still in the learning stages but i seriously want to be a meteorologist and dont laugh at me for this but i have no idea how to read those models with all the numbers i dont know what all that means
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1482. Drakoen
8:00 PM GMT on July 25, 2007
you have to use the 850mb vorticity. its there. the NOGAPS usually has a better time picking up on well defined systems than weak systems.
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1481. hurricane667
7:59 PM GMT on July 25, 2007
the 12z Nogaps run shows no signs of any development
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1480. Hokie76
7:53 PM GMT on July 25, 2007
WSI cites lower SSTs in reducing number of storms in latest forecast released today:


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1479. nolesjeff
7:54 PM GMT on July 25, 2007
Posted By: hurricane23 at 7:44 PM GMT on July 25, 2007.

12z Nogaps joins the club with some hints of development.
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1477. emagirl
7:56 PM GMT on July 25, 2007
ok thanks....just trying to learn
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1475. louisianaboy444
7:53 PM GMT on July 25, 2007
yes i know that..oh ok sorry for that i was looking at the wrong thing lol
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1474. IKE
2:52 PM CDT on July 25, 2007
TWC and their tropical update...mentioned the moisture in the GOM...heading toward Texas. Didn't say it would become tropical cyclone.

Didn't mention the CATL wave.

I love how the announcer/meteorologist stands in front of half of the satellite loop, obscuring US FROM SEEING THE CONDITIONS!

We know what they look like...just back away so we can view the satellite loop!
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1473. Drakoen
7:54 PM GMT on July 25, 2007
still few hours away from the diurnal max phase.
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1472. Drakoen
7:52 PM GMT on July 25, 2007
emagirl thats a good sign for development. although the cloud tops to the south a warming.
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1470. emagirl
7:51 PM GMT on July 25, 2007
cloud tops building as you can see on the vis

so is that a good sign for development or a bad sign
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1467. louisianaboy444
7:49 PM GMT on July 25, 2007
i'm talking about the wave in the CAtl
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1466. Drakoen
7:49 PM GMT on July 25, 2007
cloud tops building as you can see on the vis.
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1465. emagirl
7:50 PM GMT on July 25, 2007
i hear ya pat.....me too
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1464. Patrap
2:50 PM CDT on July 25, 2007
Later yall..Keep it real.The frays are just beginning.They will be plenty-o-action now,thru Oct..
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1463. Patrap
2:49 PM CDT on July 25, 2007
HAve supplies and Plenty MREs and water from 06. Wees gots sperience..LOL
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1462. IKE
2:49 PM CDT on July 25, 2007
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1461. emagirl
7:48 PM GMT on July 25, 2007
sounds like a good plan pat.....
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1459. Patrap
2:48 PM CDT on July 25, 2007
No,..sale on underwear. My supplies consist of locking the FEMA trailer and driving to Jackson ville...
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1458. emagirl
7:45 PM GMT on July 25, 2007
Posted By: Patrap at 7:44 PM GMT on July 25, 2007.

YAll keep an eye on the situations..We going to Wal-Mart!......

Stocking up on supplies??
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1457. Drakoen
7:47 PM GMT on July 25, 2007
we have to wait and see what it does during diurnal max.
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1456. Patrap
2:46 PM CDT on July 25, 2007
To keep up on relevant stuff from here.Go to the real source..nola.com Link
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1455. louisianaboy444
7:44 PM GMT on July 25, 2007
dry air will eat that thing alive
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1454. Patrap
2:45 PM CDT on July 25, 2007
Before I go.Heres the Local run on the real story.Not a Biased AP thing ..Link
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1453. Drakoen
7:43 PM GMT on July 25, 2007
Patrap it doesn't look impressive there because that measures the rainfall. the green you are seeing is 2 inches per hours. the yellow is 6 inches and the red is 8 inches.
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1452. guygee
7:32 PM GMT on July 25, 2007
Here is a good link for shear forecast Link, choose model:GFS and level: Wind Shear. Unless the BOC convection somehow shimmies right up the edge of the coast of Mexico, the shear north of the BOC is not forecast to significantly slacken out beyond 72 hours.

IMHO = IANAM. There are only a few here, like weather03, who can really say otherwise.
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1451. hurricane23
3:43 PM EDT on July 25, 2007
12z Nogaps joins the club with some hints of development.
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1450. Patrap
2:43 PM CDT on July 25, 2007
YAll keep an eye on the situations..We going to Wal-Mart!......
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1449. louisianaboy444
7:42 PM GMT on July 25, 2007
even if nothing forms out of these blowups it shows that things are really starting to fire up and get more active all around th atlantic basin
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1448. Patrap
2:42 PM CDT on July 25, 2007
That one has a lot to overcome in time

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1446. fliptill
7:42 PM GMT on July 25, 2007
it would be the visible sat.
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1445. Patrap
2:42 PM CDT on July 25, 2007
Wow a real threat there 23..LOL
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1444. hurricane23
3:39 PM EDT on July 25, 2007
Updated image from EUMETSAT.... 12z Nogaps joins the club with some hints of development.

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1443. fliptill
7:38 PM GMT on July 25, 2007
I don't really know anything but it does seem to me that there is a little spin coming off of the yucatan. anyone see that or will nothing come of it?
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1442. Patrap
2:37 PM CDT on July 25, 2007
Gee,social commentery in the tropics...That story was a big deal here...A Attorny General with his own agenda Skye.I was at Memorial and saw the conditions Dr Poe and her staff had to deal with.She and they did an amazing job with the circumstances. The Grand Jury proved that.Thus the lack of indictment.

They got no help till thursday the First of Sept.By that time..many had passed on..
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1441. Drakoen
7:38 PM GMT on July 25, 2007
the convection was more impressive this morning compared to now. It seems the cloud tops are being blown to the West.The convection has now taken on a more linear shape that the circular shape we saw this morning.

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Dr. Masters (r) 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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