Warmer Water, SUPER HURRICANES
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.
Reader Comments
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That's true. I believe a Category 1 or 2 has a chance to be retired if it hits NOLA or Mississippi this year, due to more damage it would cause from storm surge, among other things.
But a tropical storm isn't bad, and I am just waiting for when one does hit, for people to panic and the media to overhype it. Just wait.
I'm another one watching the Gulf very closely. Family stretches from the Corpus Christi area all the way to just west of New Orleans area. And that's not mentioning the ones that work in the Gulf.
paula
It's the current 250-850mb Mean Wind Analysis...
paula
These people give weather forecasts?!
Makes one wonder...
I am in total agreement that the NHC has been very cautious in idetifying areas of interest as they used to do in the past, in their TWO.
That being said there are a few areas of interest. BOC and the eastern ALT.
That gets it thru July 28th without tropical development....
000
ABNT20 KNHC 250857
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT WED JUL 25 2007
FOR THE NORTH ATLANTIC OCEAN...CARIBBEAN SEA AND THE GULF OF MEXICO...
TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH SATURDAY.
$$
FORECASTER RHOME
392...why does it actually say this....
"Statement as of 5:30 am EDT on July 25, 2007
For the North Atlantic...Caribbean Sea and the Gulf of Mexico...
Tropical cyclone formation is not expected during the next 48 hours.
$$
Forecaster Rhome"......
and why would you change it?
Another Troll in the day of Paradise, how do they let guys like wishcaster on here?
re: BoC
I noticed in the visible loop that it pulled in the low level clouds from the NE of it in the last few hours.
haven't had time to look at the forecast and data products yet - have to go get a tire patched this morning.
It may just be "funny convection", but it looks to be building around something to the NW of the large blob of convection and it appears (as I said - I haven't looked at the data) to be developing minor outflow to the SE, E and NE
Thoughts?
NAM = Not Accurate Model
WiSHcAsTeR392...why did you change the wording of the tropical weather outlook?
it is childish and irresposible behaviour for anyone to change the official wording of a reputable organisation just have fun. sic!
Anything to watch out for this morning or same old same old?
scroll down a bit Mel, you will see a comment I made about that
morning Drakoen, you get to take the reigns now Im at work lol
lol ok.
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