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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341. Tropicnerd13
8:31 PM GMT on July 24, 2007
do all low level circulation systems go north into the arctic or south into antarctica?
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340. msphar
8:26 PM GMT on July 24, 2007
What the latest on the WISH list ? I've booked my flight to San Juan for Aug 7, I hope I'm not too late...or too early.
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339. Tropicnerd13
8:28 PM GMT on July 24, 2007
can someone post that outlook that is in all caps that has all the tropical waves that are worth watching?
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338. Drakoen
8:29 PM GMT on July 24, 2007
lower level convergence too...
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337. Tropicnerd13
8:23 PM GMT on July 24, 2007
look at the eastern atlantic and africa pic on noaa.gov and look at africa. there are other disturbances about to come off that look good too. tells you it is about to start.
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336. Drakoen
8:26 PM GMT on July 24, 2007
yea sullvianweather. this shows it well...

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334. sullivanweather
8:24 PM GMT on July 24, 2007

There does appear to be an elongated area of low pressure along 35-38W, 12N
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333. Tropicnerd13
8:22 PM GMT on July 24, 2007
you guys do know we have been watching that system for 3 days, right?
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332. Drakoen
8:20 PM GMT on July 24, 2007
This is a good picture that shows the mid-lower level low.
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331. Tropicnerd13
8:21 PM GMT on July 24, 2007
oh duh i know that but it looks better than earlier. i'll see if i can find an infrared rainbow of it on noaa. thanks guys for giving me the link to it by the way.
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329. Tropicnerd13
8:20 PM GMT on July 24, 2007
ok nevermind. im going to go for today.
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328. Drakoen
8:19 PM GMT on July 24, 2007
Tropicnerd thats the area we need to monitor.
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327. Tropicnerd13
8:18 PM GMT on July 24, 2007
can you send a link that shows the open low or is that the same one i am seeing in your other link?
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326. Tropicnerd13
8:16 PM GMT on July 24, 2007
drak, what are u saying with that pic? it looks good?
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324. FLCrackerGirl
4:14 PM EDT on July 24, 2007
TexJonnie, Everyone has to Start Somewhere ;o)
Welcome to WUnderful World of Blogging!
There's Some Excellent Teachers Here...Always Feel Free To Ask Questions or Add Comments.
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323. Tropicnerd13
8:11 PM GMT on July 24, 2007
hey where'd my entry from earlier today go? it has disappeared... there's a broad llc over texas. is that just a coincidence that it is circulating or is that a low pressure system?
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322. Drakoen
8:10 PM GMT on July 24, 2007
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321. ricderr
8:01 PM GMT on July 24, 2007
hipster...don't the experts usually thow out models more for their thoughts they are incorrect and nothing to do with warm or cold core?
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318. TexJonnie
2:53 PM CDT on July 24, 2007
guess I'm a bit green... didn't realize I could access NCEP HPC on noaa. Still learning.

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315. HurrMichaelOrl
7:44 PM GMT on July 24, 2007
yeah I miss John Hope too. He used to give us gut feelings, specualtion, and hunches(which is helpful to hear), not just "there is a tropical wave in the central atlantic, we will keep an eye on it for further development." Well I could infer that just from looking at the satellite imagery.
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314. nola70119
7:49 PM GMT on July 24, 2007
StormW says its worth monitoring.....but nothing incipient. Tell you one thing, its been too quiet around here for too long.....sooner or later something will spin up.
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313. stoormfury
7:47 PM GMT on July 24, 2007
the area in the cental atlantic is the same position where Emily formed in 2005. this could be 98L in the next 24-36 hrs
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312. TexJonnie
2:44 PM CDT on July 24, 2007
Hello, all... this is my first post. been a member of WG for 2 yrs. I'm a fledgling wx-enthusiast. I saw hipdeep's post a few comments back.


What do you make of this and does this speculate a depression/storm this week? Is this a reliable source (not to question you specifically, hipdeep, or your competence)? Is this sound enough to stand alone? Don't think I've seen this NCEP HPC discussion before.

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307. HurrMichaelOrl
6:52 PM GMT on July 24, 2007
I'm sorry but which area specifically has model agreement at the current time? thanks.
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306. moonlightcowboy
7:39 PM GMT on July 24, 2007
Leftovers, I miss Hope, too!
Member Since: July 9, 2006 Posts: 184 Comments: 29641
304. stormy3
7:33 PM GMT on July 24, 2007
Thanks guys, I'll add several ax's to my list of hurricane supplies (to chop threw the roof) and a big boat to row to saftey. Noah's Ark is looking better and better, looks like he had connecions with a world class weatherman.
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300. EdMahmoud
7:31 PM GMT on July 24, 2007
RiceOwl- I mentioned earlier, if we assume a hurricane operates as a heat engine, if the heat sink warms as much as the heat source, the storms won't get any stronger.

I know its a bad deal for y'all, but as a Texas grad I'm glad to see that offensive genius Major Applewhite, who was a better college quarterback than Simms ever was, has moved on to be offensive coordinator and QB coach at Alabama. I suspect he winds up a head coach before 30, and a major school head coach before 40.
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298. catfuraplenty
7:16 PM GMT on July 24, 2007
I've said this before but I hope we get some sort of storm because a second year without a storm after stern predictions could cause many people to discount future hurricanes. We've all seen this time and again. I hope I don't have to hear any more crying people saying, "I'll never ride out another hurricane. We were lucky to get out alive."

And as for Foxnews Houston, with all the gloom and doom predicting disaster on top of the floods, I'm moving. I'm going out today and put pontoons under the mobile home so I can ride out the storm.

My biggest problem is I have no attic to blast my way through if I get flooded. Hum..perhaps its time to drag the trailer up a near by tree. We have big trees, at least 80 feet tall and sturdy. Anyone ever hear of a mobile home as a tree house? I could start a trend. ::hold it::: no one steal my idea. I thought of it first. I'm going to have to get this patented. Think of it. Groves of forests supporting new mobile home parks all over the country. It's perfect. Low cost housing + trees to fight the green house gases + added benefit of easy parking for all the cars of ours that don't work.

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297. nola70119
7:30 PM GMT on July 24, 2007
How do I get mail JP?
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296. Drakoen
7:30 PM GMT on July 24, 2007
Intersting the NHC is now noting this area. We will see what happens. we have the model support...
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295. EdMahmoud
7:26 PM GMT on July 24, 2007
Obviously if one has a medical condition and can't go w/o electricity one has to leave for any hurricane.

But, per Texas planners, if not in a mando evacuation home, not in the flood plain, and not in a trailer (or some other compelling reason such as medical conditions requiring electricity) one is supposed to prepare to ride out the storm so as to not overwhelm the trnasport system and emergency shelters.
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294. nola70119
7:28 PM GMT on July 24, 2007
Fox News I thought....
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293. IKE
2:29 PM CDT on July 24, 2007
Posted By: EdMahmoud at 2:26 PM CDT on July 24, 2007.
Pretty good looking spin about 37N, but just low clouds.

Agree...there's no convection with it.
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291. riceowl
7:18 PM GMT on July 24, 2007
There was a study reported in the journal Nature a few weeks ago that contradicts the warmer ocean -> bigger storms theory. The authors of the study were able to use sand cores from a Carribean lagoon to get a record of hurricane activity going back several hundred years to the "little ice age". They determined that large storms were more frequent in cooler periods and less frequent in warmer periods.
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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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