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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91. moonlightcowboy
2:33 PM GMT on July 24, 2007
Sailor, I'll try to find it later today and repost it.

...gotta go chase some dollar bills everyone. Hold the fort down and keep the doors closed!

Have a good day!
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2:29 PM GMT on July 24, 2007
i respectfully disagree pat haley barbour has done a wonderful job so has gene taylor and trent lott. haley put us under mandatory evac on sat morn before katrina blanco and nagin waited till sunday. but iam encouraged that bobby gindle will be a major improvement as governor when he is elected. i love our nieghbors to the west but im glad i dont have thier current leadership. on a funny note pat you do have one good leader in no his name is sean payton lol go saints
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89. txag91met
2:33 PM GMT on July 24, 2007

I think this is junk science. There are too many other factors that govern the amount of precipitation in tropical systems. Just because sea surface temperatures have warmed by about .6C since 1970 does not mean that every system in the Atlantic or Pacific should have 8% more precipitation. BTW, precip across the world has not increased 8% since 1970! NCDC states that it has increased about 2% since 1900!

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88. Patrap
9:30 AM CDT on July 24, 2007
Was quite a few wild days before Elena came thru eh Stormy2day? I was really scared as that eyewall came thru.It packed quite a wallop as she came thru. We were outside during the eye calm..and I was amazed to hear the backside coming .It ramped up to Cat 1 ..in as little as 3-4 minutes.Was a bad,bad, blow.
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87. CaicosRetiredSailor
10:30 AM EDT on July 24, 2007
moonlightcowboy at 9:51 AM EDT on July 24, 2007.
Yeah, Rick...how quickly people, gov't forgets!

According to one report, ......

Which report is that? Is it available online?
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85. moonlightcowboy
2:27 PM GMT on July 24, 2007
Exactly, Patrap!

And Stormy, Ed's statement didn't offend me; but, to say that "staying" in a Cat 1 or 2 storm on the MS coast is probably not good advice! Even if one does live more inland.

Just ask "any" that had the Katrina experience about how long the whole area was without power, decent medical care, etc...

Also, do you have any idea how many FEMA trailers are still set up in droves in beach proximity?

I'm telling you an approaching/landfalling storm, even a Cat 1 will have unprecedented ramifications!
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84. CaicosRetiredSailor
10:29 AM EDT on July 24, 2007
Good morning all,
My main pc has decided it is: "Ready for BIOS update, insert Bios update disc...."
Soooo, like NHC I am on "back up" system, rebuilding bookmarks etc....
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83. Patrap
9:23 AM CDT on July 24, 2007
Good conversation this morning.A lot of experience here and among the group.We all can do a better job in preparing.From the Federal role,State..and Local govts. Hard lessons were learned from KAtrina in all areas affected.And points inland and afar. We should strive to prevent that from ever occuring agin. And it starts with the individual.I made mistakes...I learned the hard way too. Be sure to listen to Butch Loper Thursday Night,AKA sandcrab from the blogs here. He will be discussing the same points we bantering now. Hes the Emg Mgr from Jackson County, Miss. He has a lot to give to us in information and the REAL evactuation plans for South Miss. Should be a real treat to those interested.Butch will be on the BArometerBob show thursday night...Link
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82. Stormy2day
2:24 PM GMT on July 24, 2007
Pat, I rode out Elena on the St. Pete coast - that was certainly a storm that kept everyone off guard ...darn thing went on for days, chasing people every where.
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81. moonlightcowboy
2:21 PM GMT on July 24, 2007
Saint, yes, the island barriers have been diminished. Was looking at an aerial of Ship the other day. Sad.

2. Land and building structures already blown out/away would allow surge to cause harm further inland.

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80. Patrap
9:18 AM CDT on July 24, 2007
I remember during Elena..in Miss in 85..She came up ,stalled..turned toward Tampa.and ALL of Miss dropped the ball.They were more concerned with the LAbor Day tourist than to call a MAndatory evact.And when Elena turned back towards the Miss coast.Many boats that were brought back out from the BAck bays..were almost caught in the approaching storm. It was only the ANGLE of her Impact ,..that saved the coast from a devastating surge,and the fact that Elena weakend rapidly inland. I rode it out in Long Beach. And saw ALL the Local errors from that. So..its not responsible Leadership in many cases. Thats why one must have a plan.And implement it when one feels threatened,even before an Offical evact is called
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79. Drakoen
2:21 PM GMT on July 24, 2007
anyone notice this from the HWRF?
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78. Stormy2day
2:19 PM GMT on July 24, 2007
MLC, I didn't read Ed's comment as bad advice that could get people killed...now if he had stated that no one should evacuate for a Cat 1 or Cat 2 ...but, that is not what he stated.

Local evacuation plans are important to follow and that applies to the flip side as well. When folks evacuate that should NOT that causes grid lock on the roads and blocks evacuation routes for those that do need to leave. Folks should always opt for the closest safe evacuation site (local friends and family in a non-evacuation zone is best) but often folks that are evacuating take a "leave the country" route that depletes available fuel and blocks evacuation routes.

We are quick to rally people to evacuate but balancing that with evacuating at the right time to the right place is also an important factor in saving lives.
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77. Patrap
9:16 AM CDT on July 24, 2007
To be sure..leadership counts..its no better in Miss than here.We all Americans,..it how one responds to the threat that counts.Calamity knows no borders saint..only mens minds do.
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76. moonlightcowboy
2:15 PM GMT on July 24, 2007
Patrap, I surely hope that's the case and that Emergency Teams and the Call is in place and ready. Not saying that it'll happen; but I can just see the "evacuation" mess already. Even that will be chaotic!

I'll try to find the report and repost it. But, one thing's for sure, the MS coast is particularly vulnerable (and NOLA, too in MHO) to any storm making landfall. Let alone a major!
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75. Drakoen
2:16 PM GMT on July 24, 2007
People should treat hurricane 1 category higher than what they are (Cat 1 prepare for a cat 2; cat 2 prepare for a cat 3; etc...)
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74. MissBennet
2:14 PM GMT on July 24, 2007
Morning all,

I've been on vacation since Friday, anything of interest I should know about? According to the blog, looks like nothing! =S

If not, I plan to bury my nose in Harry Potter and not surface for a week.
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73. Patrap
9:14 AM CDT on July 24, 2007
For sure,MLC...the Hype sells,as the Dr. points out in that article. I see your point.
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2:07 PM GMT on July 24, 2007
moonlight i live in south ms and i will tell you if thier is a cat 1 or 2 people will take it serious. and as far as your top five reasons you left out the most important the destruction of barrier islands horn ship chandeleurs petit bois and even deer. the surge would be far more severe because that main reason big article in our local paper concerning the barrier islands, also we are fortunate to have much better local and state leadership in ms than lousiana does. the newbies are reminded everyday by passing the destruction that is still here lifelong resident of ms gulf coast and huirricane vet of camille freddy elena georges and katrina have a good day
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71. EdMahmoud
2:13 PM GMT on July 24, 2007
Well, Ed, it's that kind of thinking that's going to get more people killed.

That people should treat a Cat 1 or Cat 2 as a Cat 3 or Cat 4 because some storms intensify quickly and unexpectedly?
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70. Patrap
9:12 AM CDT on July 24, 2007
The FEMA trailer issue is still a reason for concern.Evactuations even in a Strong TS are now in the Evac criteria.Plus...the people here and over there are prepared to move even before an official Evacuation is called.
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69. moonlightcowboy
2:12 PM GMT on July 24, 2007
Patrap, sure, I understand surge. I am just repeating what the report/survey found.

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68. StormJunkie
2:10 PM GMT on July 24, 2007
Morning again y'all ☺
Thanks for the update Dr M!

I find this statement interesting though...
but none of the other models are showing this.

What is the 06z GFS showing later in the forecast period?

Back to work. See y'all later
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67. Patrap
9:07 AM CDT on July 24, 2007
To be sure MLC..that would not be the case.If anything...the folks in ther Miss,LA,Ala...area are more H savvy than ever before,The Emg Mgrs..some whom I talk to on aregular basis ,all report that Evactuations will be called sooner.And those older folks who thought that since they survived CAmille in 69,that they could ride out KAtrina. That kinda thinking has evaporated.As far as surge goes..angle of impact..tide timing..all have an impact on surge.
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66. Drakoen
2:06 PM GMT on July 24, 2007
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65. moonlightcowboy
1:58 PM GMT on July 24, 2007
Well, Ed, it's that kind of thinking that's going to get more people killed.

Here's what the report said:

A MS coast landfalling Cat 1 or 2 storm could be as dangerous at a Cat 3 or 4 storm. Here's why:

1. Storm surge would be as dangerous because of sediment blown up from Katrina. Shallow waters predicted to make surge even more serious now, making the Cat 1 or 2 more dangerous than perceived.

2. Land and building structures already blown out/away would allow surge to cause harm further inland.

3. Number of people working/living on the coast from elsewhere that have never had "any" hurricane experience.

4. Number of people still living in FEMA trailers.

5. Survey reports that says large number of people would "stay" in Cat 1 or 2 storm.

...apparently storm apathy abounds!!!
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64. DaytonaBeachWatcher
2:01 PM GMT on July 24, 2007
Yes the GFS hasnt deviated much from last night. Also of slight interest the GFS and NAM both are showing a low going from the BOC to the NW GOM by friday.
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62. Drakoen
1:58 PM GMT on July 24, 2007
Hello everyone. I see that the UKMET and the GFS are showing possible development near the CV islands.
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61. EdMahmoud
1:53 PM GMT on July 24, 2007
About riding out Cat 1 or Cat 2 storms- people in well built homes not immediately on the beach can ride out cat 1 or Cat 2 storms. If they stay Cat 1 or Cat 2 storms.

But considering how quickly Hurricane Charley went to Cat 4, it is probably best to treat a Cat 1 or Cat 2 as a potential Cat 3 or Cat 4, unless you live far enough North with offshore water cold enough that you can be certain the storms won't intensify, and even that might be riskier than some people would want.
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60. EdMahmoud
1:46 PM GMT on July 24, 2007
In my un-expert opinion, with a BS from a major university, but dealing mainly with multi-phase fluid flow in hetergeneous media, looking at the Caribbean system on satellite, I still say nothing in July, and six to eight additional storms, mostly in the busiest 4 weeks around September 10th, for a total of eight to ten.

I do look at stuff on the internet a lot, have checked out some books, my wife got me the Ucellini and Kocin AMS book about 25 major Northeast snow storms.

So, I consider myself an amateur, but a motivated one.
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59. emagirl
1:50 PM GMT on July 24, 2007
i agree with you floridarick
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58. moonlightcowboy
1:47 PM GMT on July 24, 2007
Yeah, Rick...how quickly people, gov't forgets!

According to one report, a Cat 1 or 2 storm if it hits the MS coast (and NOLA, too) is reported to be equivalent in danger previously as a Cat 3 or 4...and still there is that mentality that people can "ride" out a Cat 1 or 2 storm! Makes no sense. Maybe there's NOT enough awareness created still...will people, gov't ever learn?
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57. gthsii
1:49 PM GMT on July 24, 2007
aahhhh...jp...thanks so much. the gritting of my teeth will now stop...
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56. gthsii
1:45 PM GMT on July 24, 2007
hey jp...i've never created a blog on here but i am a paid sub...i'll check into it. thanks
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55. EdMahmoud
1:41 PM GMT on July 24, 2007
If one thinks of a hurricane as something like a Carnot engine, warmer water = stronger hurricanes is true only if the heat sink warms less than the heat source.

If the upper atmosphere were to heat at the same rate as the oceans, than I don't think the storms would increase in strength.
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54. FloridaRick
1:41 PM GMT on July 24, 2007
in reference to the article you posted, I would like to say that is why some of us wishcast. Working in an emergency management field we find that the more seasons you go without a hit, the more likely people as well as government become complacent. Funding starts to be cut, people start to ignore the situation. It was amazing to me here in Florida to watch after 04 season and see the positive changes that were being made in the 05 season. But 06 came and went without incident and it seems our folks are going back to the old way of doing business.
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51. gthsii
1:43 PM GMT on July 24, 2007
is there anyway on this blog to ignore a person for good? i see using the [-] sign you can hide a post, but how to ignore forever...and dont ask me who, i dont want to start a flame war.
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50. moonlightcowboy
1:42 PM GMT on July 24, 2007
Good morning, all!

So, our wCarib wave still may spit something out? wow! Interesting. What's the scoop?
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48. weathermanwannabe
9:32 AM EDT on July 24, 2007
Thanks Dr. M; warmer SST's = more intense storms/wind speeds.....Hope nothing significant gets into the GOM this year...Local temps around the FL northern Gulf coast waters right now are around 86 degrees...Very warm and it will probably increase to around 88-90 by mid/late August...
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46. Tazmanian
6:35 AM PDT on July 24, 2007
a note for evere one oh trys to go to the nhc web site today

The NHC website is in backup mode. Some information may not be available

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43. DaytonaBeachWatcher
1:14 PM GMT on July 24, 2007
that system that the NAM is showing in the GOM was way down by south america last friday and at that time the NAM was showing it doing exactly what it has been doing the last few days. I think that low is gonna cross over and into the GOM, just dont know what to make of it after that. The GFS seems to see the same thing now.

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42. crownwx
9:26 AM EDT on July 24, 2007
Found this article interesting and relevant to this blog. It is from USA Today:

Poll: Little 'Hurry' in Hurricane Zones
Publication date: 2007-07-24
By Patrick O'Driscoll

Nearly one-third of residents in U.S. coastal areas vulnerable to hurricanes say they won't obey orders to evacuate if a major storm threatens, according to a new survey on preparedness released today.

Despite the nightmare experience of Hurricane Katrina in 2005, the poll also found that almost two-thirds of New Orleans residents don't know the location of an evacuation shelter. More than half have not prearranged with their family where to meet after a storm. In other states, lack of a post-storm meeting plan is even higher: 66%.

"Our surprise was we thought the power of Katrina would leave a longer legacy," says project director Robert Blendon of the Harvard School of Public Health. His team surveyed 5,046 adults within 20 miles of the coasts in Alabama, Florida, Georgia, Louisiana, Mississippi, the Carolinas and Texas.

In a survey last year, only one-fourth of hurricane-zone residents said they would not evacuate.

The Harvard survey comes about a month before the normal peak of Atlantic hurricane season.

Two tropical storms have formed so far this year: Andrea in May and Barry in June.

Blendon says safety and security concerns rank highest among those unwilling to flee. More than half fear overcrowded roads. One-third fear danger during evacuation and theft or damage of property left behind. Shelter conditions also are a worry. Two-thirds of respondents think shelters would be unsanitary, too crowded and short of water.

Among those reluctant to leave, three-quarters say their houses are sturdy enough to withstand hurricanes -- even residents of mobile homes, which are considered the least-likely structures to survive.

Blendon says his team was "really taken aback" that a quarter of mobile-home residents who would not leave believe that their houses can withstand a Category 3 storm, with winds of 111-130 mph.

Blendon says New Orleans leads in one positive category: It boasts the fewest number of respondents who say they would refuse to evacuate, only 14%. "But they have the highest share of people who don't know where a shelter is," he adds.

New Orleans and Louisiana officials downplayed the shelter issue, saying details about where to take cover depend on the path of an approaching storm and specific needs of those seeking shelter -- families, the disabled or people with pets.

Terry Ebbert, the city's head of homeland security, admits concern that 51% in New Orleans haven't arranged for family meet-ups afterward. "Responsibility for individual planning rests not with government but with individuals," he says.
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41. emagirl
1:27 PM GMT on July 24, 2007
things were just way to quiet last year i get a feeling it just can not be like that 2 years in a row
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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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