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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1591. StormJunkie
10:08 PM GMT on July 25, 2007
TN, you can find several very good model pages from here, as well as some great imagery and tropical pages.
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1590. ryang
6:09 PM AST on July 25, 2007
Hey Bama...
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1589. Bamatracker
10:08 PM GMT on July 25, 2007
get what?
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1588. Tropicnerd13
10:06 PM GMT on July 25, 2007
where do yall get that anyway?
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1587. Bamatracker
10:07 PM GMT on July 25, 2007
TN13....no 98L yet...therfore now model runs for 98L
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1586. ryang
6:07 PM AST on July 25, 2007
It isn't 98L yet Nerd.
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1585. philliesrock
6:07 PM EDT on July 25, 2007
Off the CV Islands.
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1584. Tropicnerd13
10:04 PM GMT on July 25, 2007
can someone post the model runs for almost 98l? are they non-existent? if they dont exist, tell me. and if someone could find a model run for anything in the atlantic, please post it.
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1583. ryang
6:05 PM AST on July 25, 2007
Oh... Never mind...LOL
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1582. ryang
6:02 PM AST on July 25, 2007
Where Philles?
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1580. Tropicnerd13
9:58 PM GMT on July 25, 2007
hi guys. im back. soon to be td03 or at least 98l looks a little unhappy. hows the gulf blob and the yucatan blob? are they colliding? DPATS (dont pay attention to spelling)
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1579. hurricane23
6:02 PM EDT on July 25, 2007
18z GFS coming we'll see what it looks like when the complete run rolls in.As i suspected earlier upper level winds dont favor development in the GOM.
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1578. weathermanwannabe
5:55 PM EDT on July 25, 2007
Agree that shear is inhibiting development in BOB/GOM. but, all of that moisture and convection may not be there in 48 hours when the shear drops down as the recent front is stalling/lifting back up. As such, I would not be concerned at this point (just a rain event)..
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1577. RL3AO
5:02 PM CDT on July 25, 2007
Dennis Phillips, local ABC weather guy just said that he expects this trough to remain in place over Florida for the next ten days.

That completely contradicts Dr. M's post that that on or about the 29th we would have a major weather pattern change to the trough lifting out and high pressure building in much like '04 and '05.

It isn't that simple. 2 weeks ago, the models showed a shift in the weather pattern. I don't know what they show now.
1576. philliesrock
6:01 PM EDT on July 25, 2007
WOW...GFS through 84 hrs shows 2 DEPRESSIONS off the African coast!
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1574. charley04survivor
9:59 PM GMT on July 25, 2007
I am in Dallas next week, so I hope nothing spins up.
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1573. MissBennet
9:59 PM GMT on July 25, 2007
ok thanks! Leaving work, see you all later! And thanks for the answers Blink.
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1572. IKE
4:59 PM CDT on July 25, 2007
A link to the GFS...the latest is the 18UTC...

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1571. philliesrock
5:59 PM EDT on July 25, 2007
GFS shows a 1008 mb low in 72 hours.
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1570. Blink
9:56 PM GMT on July 25, 2007
Either way, this blob will probably give Texas more rain unfortunately. Only one model(Nam) develops it into something as of now.
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1569. charley04survivor
9:58 PM GMT on July 25, 2007
I believe Dennis Phillips
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1568. louisianaboy444
9:55 PM GMT on July 25, 2007
haha man thats 12 and a half days out whoa brother slow down
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1567. CaicosRetiredSailor
5:56 PM EDT on July 25, 2007

just sent you mail
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1566. scwindsaloft
9:54 PM GMT on July 25, 2007
Where is the site for a GFS model that goes out 300 hrs?
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1564. moonlightcowboy
9:51 PM GMT on July 25, 2007
The blob in the near CATL is looking better. Wave is tilted and NHC says has low level cyclonic turning. There's a ton of dry air at 15n and above. So, it's gonna have to keep tracking westward towards the islands before it can spin out of the Itcz. Still, I think it could be 98L soon and think it may be take 50w or better for it to do something. JMHO

Like, Jp, now (lol)...I'm headed out, bbs!
Member Since: July 9, 2006 Posts: 184 Comments: 29617
1563. MissBennet
9:53 PM GMT on July 25, 2007
Ok good. I'll trust ya! Any chance this baby will develop? I've seen a couple of models posted that says it will get bigger, but how big? Depression? TS?

Let's just hope those Texans like being wet.
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1562. StormJunkie
9:50 PM GMT on July 25, 2007
Taz, that is 300hrs out. You can pretty much bet that scenario will change much over coming days. No chance of any model accurately predicting a storm intensity 300hrs out.
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1561. Blink
9:50 PM GMT on July 25, 2007
There's some spin to it. Still nothing to be wary of.
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1560. louisianaboy444
9:41 PM GMT on July 25, 2007
It looks like a new burst of convection is forming along the southern tip of that cloud mass in the gulf with the wave trying to get a more circular shape....something is trying to form but wind shear isnt allowing it to....what is that near the yuctuan not saying it looks threatening or anything but it has been blowing up with convection nicely all day with more trying to form?
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1559. StormJunkie
9:47 PM GMT on July 25, 2007
To me, this looks like it is setting up to be a significant Cape Verde season. It has been quite a while since we have seen one of those. Just my opinion though, so take it with a grain of salt or two :~)
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1558. MissBennet
9:46 PM GMT on July 25, 2007
Blink, is that spinning or is it just my imagination?
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1557. Tazmanian
9:47 PM GMT on July 25, 2007
ok IKE
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1556. IKE
4:45 PM CDT on July 25, 2007
TAZ....STL says storms can be stronger...maybe much stronger then what the models show.
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1555. StormJunkie
9:41 PM GMT on July 25, 2007
Good to see you Saint, but hey take it easy there. The EATL, soon to be CATL, is likely the area with the most potential to develop right now...

That said, I saw what you are talking about TRR, Interesting, but shear is pretty high. Good to see you as well.

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1554. Blink
9:45 PM GMT on July 25, 2007
This is a very good view of the convection in the BOC.


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1553. Tazmanian
9:43 PM GMT on July 25, 2007
dos the GFS show how strong whe it makes land fall on the Outer Banks
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1552. philliesrock
5:43 PM EDT on July 25, 2007
Yeah I know IKE. I just got home so I just found that out...LOL
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1551. IKE
4:41 PM CDT on July 25, 2007
philliesrock...the new GFS 18Z model run is coming out now...out thru 30 hours.
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1550. philliesrock
5:38 PM EDT on July 25, 2007
Long-range GFS:

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1549. TexasRiverRat
9:39 PM GMT on July 25, 2007
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9:28 PM GMT on July 25, 2007
could someone please tell me what drken is looking at in the central atlantic? he has been constantly posting the same maps over and over and totally focusing on it alone does he live on aship in the itcz for thats all it is gee lol
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1547. Tazmanian
9:39 PM GMT on July 25, 2007
Member Since: May 21, 2006 Posts: 5100 Comments: 117351
1546. TexasRiverRat
9:38 PM GMT on July 25, 2007
The gulf VIS shows a spinning action at the southern end of the cloud mass in the BOC
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1545. GainesvilleGator
9:36 PM GMT on July 25, 2007
If the Cape Verde season doesn't start until a few more weeks we still may have tropical threats in the GOM or Carribean since wind shear is expected to decline over the coming weeks. The SAL doesn't seem to be penetrating into the Western Carribean or GOM so wind shear seems to be the most inhibiting factor.

There is plenty of warm water in the above mentioned areas. If wind shear drops below 10 Knots then we could be looking at serious trouble very soon. Keep in mind that Florida is only 1 well placed category 4 hurricane away from having the rest of the private insurers making a quick exit. If you live in Florida you may have a state run propery insurance plan in the near future. I think raising the state sales tax 1/2 cent or cent for the insurance fund could be on the table.
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1544. scwindsaloft
9:26 PM GMT on July 25, 2007
Texas really doesn't need that blob of rain!
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1543. philliesrock
5:27 PM EDT on July 25, 2007
The long-range GFS shows Chantal and Dean forming in the next 16 days. Chantal is a storm hitting the Outer Banks and scraping New England, and Dean is a fish storm.
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1542. MissBennet
9:31 PM GMT on July 25, 2007

Don't know if anyone's posted this yet, but Dr. Masters has been quoted on Yahoo News (drawing from Miami's Reuters). Here's the article:

Worst of Atlantic hurricane season still to come

He's quoted near the bottom. Way to go Dr. M!
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Dr. Jeff Masters' WunderBlog


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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