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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1741. pottery2
8:41 PM AST on July 25, 2007
Very good post, STL
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1740. Tropicnerd13
12:40 AM GMT on July 26, 2007
it seems you have the allison pretiction nailed. that system in the gulf is getting to be a pain. there's thunder and lightning and rain and wind here. im about to update my blog. i'll tell you when im done.
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1739. Patrap
7:42 PM CDT on July 25, 2007
No, the USMC did most of that StormW..thus the meds..LOL..Nitey guys.
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1738. benirica
12:41 AM GMT on July 26, 2007
one thing, how do we see the wave west of the Cape Verdes looking good? it seems small and not really significant.
It looked nice before but now I just cant see anything in it.
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1735. benirica
12:39 AM GMT on July 26, 2007
hmmm i see
ok lets watch it then
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1734. Tropicnerd13
12:37 AM GMT on July 26, 2007
ok guys hows our wave holding up? and the texas coast one, how's it doing? it seems that the systems we are watching are getting stronger. anyone think they will develop? please post your opinionated percentages for development and location of development.
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1730. Patrap
7:39 PM CDT on July 25, 2007
Meds ruining my mind,,LOL
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1729. StormJunkie
12:38 AM GMT on July 26, 2007
less dust, lower shear, the ITCZ is further N.
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1728. StormJunkie
12:38 AM GMT on July 26, 2007
lol jp ☺
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1726. benirica
12:36 AM GMT on July 26, 2007
interesting to watch.
anything to make these CATL waves more promising for development then all the others weve watched?
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1724. StormJunkie
12:37 AM GMT on July 26, 2007
Evenin' pat Thanks, luv dem dogs!

Hey just guessing, my odds don't mean squat :~)
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1723. guygee
12:34 AM GMT on July 26, 2007
MichaelSTL - The context for my post was that people are comparing 2006 to 2007. So yes, we do not have an El Nino in 2007. But even with the late-developing El Nino, 2006 ended up being an "average" year in most respects considering climatology from 1945-present.
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1718. StormJunkie
12:33 AM GMT on July 26, 2007
benric, the W Gulf...10% chance maybe imho

The E/CATL..40%...imh guess....
Member Since: August 17, 2005 Posts: 26 Comments: 17143
1717. Tazmanian
5:30 PM PDT on July 25, 2007
we may have some in her in the gulf at the sfc

Conditions at 42002 in the gulf

Wind Direction (WDIR): SE ( 140 deg true )
Wind Speed (WSPD): 11.7 kts
Wind Gust (GST): 13.6 kts
Wave Height (WVHT): 6.2 ft
Dominant Wave Period (DPD): 7 sec
Average Period (APD): 5.8 sec
Mean Wave Direction (MWD): SSE ( 167 deg true )
Atmospheric Pressure (PRES): 29.92 in
Pressure Tendency (PTDY): -0.03 in ( Falling ) Air Temperature (ATMP): 82.2 F
Water Temperature (WTMP): 84.4 F
Dew Point (DEWP): 75.2 F
Heat Index (HEAT): 89.2 F
Member Since: May 21, 2006 Posts: 5096 Comments: 117211
1716. stormwatcher247
12:32 AM GMT on July 26, 2007
I like to know what buoy you're looking at
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1715. benirica
12:31 AM GMT on July 26, 2007
sooooo i bet you guys have been asked this a few times already today but... what out there to watch.
what would be THE SPOT or the TWO SPOTS and how much of a chance do they truly have?
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1714. guygee
12:31 AM GMT on July 26, 2007
Posted By: MichaelSTL at 12:29 AM GMT on July 26, 2007.
one only need to go back a few years to find a similar season.

Yeah, but those seasons (1994, 1997, and 2002) had EL NINOs.

So did 2006, what is your point STL?
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1713. moonlightcowboy
12:30 AM GMT on July 26, 2007
Hey, StormW! How are you?

...according to TWD, there's another wave (in a better position) to watch, now!

What's your take on it?
Member Since: July 9, 2006 Posts: 184 Comments: 29617
1712. stormwatcher247
12:30 AM GMT on July 26, 2007
I don't see it!
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12:27 AM GMT on July 26, 2007
k m were are you located
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1706. moonlightcowboy
12:25 AM GMT on July 26, 2007
Tropical weather discussion
NWS TPC/National Hurricane Center Miami FL
805 PM EDT Wed Jul 25 2007

Based on 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...Tropical waves...

Tropical wave will be introduced along 27w S of 17n moving W
about 15 kt. There are several indications of this wave. 1...a
weak signal is noted in the dakar sounding between 00z and 12z
on the 23rd. 2...a signal is noted in the sal sounding between
12z on the 24th and 00z on the 25th mainly in 850-900 mb level.
3...a 1946z Quikscat pass shows a weak circulation centered W of
the cape verdes near 13n27w. Scattered moderate convection is
from 12n-15n between 25w-28w.

...sounds like another (in a little better position) to watch, now, too!
Member Since: July 9, 2006 Posts: 184 Comments: 29617
1705. stormwatcher247
12:25 AM GMT on July 26, 2007
There's obviously a circulation in the BOC. However, eye may be right, the buoys are not indicating this on the surface
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1704. AndyN
12:21 AM GMT on July 26, 2007
I think alot of people are getting caught up in the hype and predictions. Afterall Katrina wasn't until the end of August and Rita in September and before that Ivan was in September.
Member Since: December 29, 2005 Posts: 1 Comments: 551
1703. guygee
12:23 AM GMT on July 26, 2007
The 2006 hurricane season was a fairly normal hurricane season. The only slightly unusual aspects were the early end of the season and the fact that no hurricanes made U.S. landfall. Let Dr. Master's speak about the 2006 season from one his old blogs:

"The remarkably unremarkable Atlantic hurricane season of 2006 has now officially passed into the history books with the arrival of November 30. The nine named storms, five hurricanes, two intense hurricanes, 50 days with a named storm, and 20 days with a hurricane were all very close to the averages one expects for an Atlantic hurricane season."
"A few interesting highlights from the 2006 Hurricane Season, taken in part from Dr. Bill Gray and Phil Klotzbach's forecast team at Colorado State University [SUMMARY OF 2006 ATLANTIC TROPICAL CYCLONE ACTIVITY Section 4]:

-It was another early-starting season. Alberto formed on June 11. The climatological average date for the first named storm formation in the Atlantic, based on 1944-2005 data, is July 10.

-The 9 named storms, 2 intense hurricanes, and 50 named storm days were the lowest observed since the El Nino year of 1997.

-This is only the 11th year since 1945 that no hurricanes have made United States landfall.

-No Category 4 or 5 hurricanes formed in the Atlantic basin this year. This is the first year with no Category 4-5 hurricanes in the Atlantic since 1997.

-No named storms formed in October. This is the first time that no named storms have formed in October since 2002. Prior to 2006, only eleven years since 1950 witnessed no named storm formations in October.

-Only two named storm days were observed in October (from Isaac which formed in late September). This is the fewest named storm days in October since 1994, when zero named storm days were observed.

Notice that for all of the "highlights' of 2006, one only need to go back a few years to find a similar season.
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1699. weatherblog
12:15 AM GMT on July 26, 2007
I have a new blog up discussing our two disturbances...a lot of information there.

Please stop by and leave a comment or two...

I'll be discussing the BOC disturbance and our CATL wave...you'll see all my opinions there.

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1698. eye
12:17 AM GMT on July 26, 2007
right now it is, but it is moving into unfavorable shear...like jp says...20kts and over is considered unfavorable.
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1696. moonlightcowboy
12:17 AM GMT on July 26, 2007

OKAY, I though I'd try to lighten things up with a cartoon! LOL

...not saying, not substantiating...just drawing mostly for fun. However, I do think we'll see our blob resurface as it keeps moving west. It has to stay under 15n until it reaches the islands as dry air is to the north but becoming less prevalent. I think it'll break from the Itcz between 40w and 50w and be declared an invest slightly further west.

...now, REST EASY, gang...just a bad drawing (thought I'd try one out) without any substantial evidence to support development, trek and status! Still, I think we'll have to watch it...after all, still not much else out there. Yes, it's still early, but suspect a named storm before July's end still.

Member Since: July 9, 2006 Posts: 184 Comments: 29617
1695. eye
12:16 AM GMT on July 26, 2007
it is called, not wishcasting a surface low when all the buoys in the area have held constant all day...plus rocket shear it is moving into....just going to be more unwelcome rain to Texas....but nothing organized.
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1694. Stormchaser2007
8:13 PM EDT on July 25, 2007
eye its under 10knts:
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1693. KoritheMan
7:10 PM CDT on July 25, 2007
can't wait till august then it will be wait till sept wait till oct wait till nov wait till next season lol

You are right, man. You are so right. Jim Cantore and Steve Lyons need to learn some lessons from you, man. I mean yeah the African waves have dissipated I mean wow... Considering over half the waves we've been tracking weren't even invests, much less mentioned in any of the TWO's half the time. Over half the time, the waves are just waves, and we watch them cause there's nothing else to watch.

That will change soon... Or will it? This season sucks. Nobody can make forecasts via climatology and long range... we should make them by saying the first two months are inactive.... Oh my... You are right. Give me your knowledge, oh person who has a pHd in meteorology.
Member Since: March 7, 2007 Posts: 603 Comments: 21904
1691. pottery2
8:13 PM AST on July 25, 2007
good evening, everyone,
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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