Hurricanes Getting Stronger?

[ConvergenceZone]

just noticed this posted on the cnn page: Forgive me if it's already been posted, but I couldn't find it. Interesting read.


http://www.cnn.com/2005/TECH/science/07 ... index.html

[WeatherEmperor]

I was just reading that article at Yahoo news. very interesting.

<RICKY>

[Anonymous]

NO. When I spoke with Dr. William Gray this past May, he told me himself...Global Warming does not cause more hurricanes! It's a cycle, and people are too focused on global warming when hurricanes are the real problem.

[ConvergenceZone]

Well, I'm sure he has an opinion on it just like anyone else who's educated in the matter. Other experts disagree with him though. There are alot of experts out there where that's all they do is study the effects of global warming and nothing else, and some of them seem to be pretty alarmed about this.

I guess we'll just have to wait and see what future studies show.

[clfenwi]

NO. When I spoke with Dr. William Gray this past May, he told me himself...Global Warming does not cause more hurricanes! It's a cycle, and people are too focused on global warming when hurricanes are the real problem.

And Dr. Emanuel isn't saying that... from the article

However, the research doesn't suggest global warming is generating more hurricanes and typhoons.

This is the opening paragraph of the paper

Theory(1) and modelling(2) predict that hurricane intensity should increase with increasing global mean temperatures, but work on the detection of trends in hurricane activity has focused mostly on their frequency(3, 4) and shows no trend. Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming. My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and—taking into account an increasing coastal population—a substantial increase in hurricane-related losses in the twenty-first century.

http://www.nature.com/nature/journal/va ... 03906.html

I won't comment until I've read the whole thing for myself...

[Tampa Bay Hurricane]

It is cycles that cause increased activity, but Global warming exacerbates hurricane intensity is what I think Emmaneul is trying to say.

[ConvergenceZone]

I agree with ya clfenwi.

Also, It's just the idea of increased sea surface temperatures, which would increase tropical activity, and that makes sense. I don't much about it myself. I need to study it a bit more before I'm qualified to comment much on it.

Until then I'll just stay open-minded that either side could be right.

[elysium]

Most of the theories in support of the above hypothesis are based on incomplete studies conducted outside conventional meteorological institutional supervision. It can largely be ignored in deference to the 50 year rule which basically states that any body of scientifical research must first pass the rigors of the compilation of lengthy, comprehensive and detailed analysis, structured around those institutions governed by the overseers, where any radical departure from the established methodology leading to some of the hasty assumptions one might find in pseudo-scientific journals of only parvenu value, can thereforthwithly be offset. Needless to say remedial efforts and in depth analysis go hand in hand. Too harsh for the layman's ears.

[WindRunner]

I doubt that looking at the past thirty years worth of storms could provide substantial evidence. If it did, then we're all gonna die by 2035.

[Hurricanehink]

Look at the 1950's
1950: 13/11/8, with 3 hurricanes of Cat. 4 or higher. 85% Hurricane rate, 62% major hurricane rate (73% of hurricanes became major hurricanes)
1951: 10/8/5. 80% hurricane rate, 50% major hurricane rate (63% of hurricanes became major hurricanes)
1952: 7/6/3. 86% hurricane rate, 43% major hurricane rate (50% of hurricanes became major hurricanes)
1953: 14/6/4. 43% hurricane rate, 29% major hurricane rate (67% of hurricanes became major hurricanes)
1954: 11/8/2. 73% hurricane rate, 19% major hurricane rate. (25% of hurricanes became major hurricanes)
1955: 12/9/6. 75% hurricane rate, 50% major hurricane rate. (67% of hurricanes became major hurricanes)
Average: 11.2/8/4.7 71% hurricane rate, 42% major hurricane rate. (59% of hurricanes became major hurricanes)
Compared to the last 5 years
2000: 15/8/3. 53% hurricane rate, 20% major hurricane rate. (38% of hurricanes became major hurricanes)
2001: 15/9/4. 60% hurricane rate, 27% major hurricane rate. (44% of hurricanes became major hurricanes)
2002: 12/4/2. 33% hurricane rate, 17% major hurricane rate. (50% of hurricanes became major hurricanes)
2003: 16/7/3. 44% hurricane rate, 19% major hurricane rate. (43% of hurricanes became major hurricanes)
2004: 15/9/6. 60% hurricane rate, 40% major hurricane rate. (67% of hurricanes became major hurricanes)
Average: 14.6/7.4/3.6 50% hurricane rate, 25% major hurricane rate. (48% of hurricanes became major hurricanes)

The conclusion, we are getting more storms, but the hurricanes are as active, if not less than the 1950s. But Global Warming couldn't have been around back then?!?!?!? This shows it is a cycle.

[Air Force Met]

NO. When I spoke with Dr. William Gray this past May, he told me himself...Global Warming does not cause more hurricanes! It's a cycle, and people are too focused on global warming when hurricanes are the real problem.

And tropical activity is down globally. If it were global warming...it would be up globally. It's a cycle. We'll see where the "global warming" theorists are in 15 years when we are out of this current cycle and getting 8-10 storms a year again.

[dhweather]

NO. When I spoke with Dr. William Gray this past May, he told me himself...Global Warming does not cause more hurricanes! It's a cycle, and people are too focused on global warming when hurricanes are the real problem.

And tropical activity is down globally. If it were global warming...it would be up globally. It's a cycle. We'll see where the "global warming" theorists are in 15 years when we are out of this current cycle and getting 8-10 storms a year again.

That's a battle you can not win. They'll claim the "progress" is due to
the restrictions put in place. Had we not done what we did, things
would be 10 times worse.......

[LSU2001]

I may be wrong but I think the gist of the article is that global warming [does notincrease the number of storms but that it does impact the intensity of the storms that develop. I think that this idea could have merit and remember it is not scientific to close your mind to alternate theories or ideas. The goal of science is to search out truth and to apply logic and reason to all possiblities. Remember a few hundred years ago the earth was flat and the sun revolved around the earth. Science is about searching not making definitive statements. Theories change as more data is gathered so always keep an open mind.
TIm

[clfenwi]

Dr Emanuel's starting point is the idea that the cost of damage in a hurricane rises with the cube of wind speed. His Power Dissipation Index(PDI) is the sum of the cube of the maximum sustained winds recorded over the six hour period throughout the life of the storm (similar, but different from the Accumulated Cyclone Energy index used by NOAA).

His first plot shows the PDI for the North Atlantic from 1950 to present with the average September SST over 'a prime genesis region' from 1930 to present. For PDI the plot shows 1995 (or so) being equal with the previous peaks in the early 1950's and a slightly low peak at 1964 (or so) The PDI trend overall from mid 1960''s to the early 70's is down followed by oscillations until the mid 90's. From 1995 there is a virtual straight line increase in PDI and it shows 2004 about 50% higher than any previous peak and about more than 100% higher than the PDI of 1970.

A second plot shows PDI from 1955 to present and July-November mean SSTfor the western north Pacific. This plot shows a realtively steady increase in PDI from the early 1970's to a max in (approx) 1996 followed by a sharp drop and then a return to a level about 20% lower than the absolute max and 75% higher than the 1970 number.

The third plot shows a combined PDI for the Pacific and Atlantic basins. It shows a level amount through the 50's and 60's then a minimum in the early 70's. From there a more or less steady increase to a maximum in 1996 followed by a sharp drop then return to a level near the absolute max and about 80% higher than the PDI of the 50's-60's.

In his discussion he notes that only part of the increase in PDI can be explained by the increase in SSTs. Existing theory says that the SST increase should have only caused an increase in PDI of only 10%.

He then approximates the effects caused by a higher atmospheric temperature overall and 'explains' an increase of about 40%, still pretty short of the increase he observed.

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The point of controversy lies in his method of determining wind speeds for his PDI.

The Associated Press article incorrectly states " For example, the MIT researcher did not consider wind speed information from some powerful storms in the 1950s and 1960s because the details of those storms are inconsistent."

The study does consider the wind speed information, however it does not do so in an unadjusted form. Emanuel took research by Chris Landsea to justify adjusting downward pre-1970 windspeeds in the Atlantic and pre-1973 windspeeds in the Pacific. Winds after 1973 are not adjusted.

The AP article suggests that Landsea does not agree with how the wind speeds were adjusted.

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The adjustment probably explains why his graph for PDI differs in maximums from that shown by NOAA's ACE index ( http://www.cpc.ncep.noaa.gov/products/o ... igure4.gif ) The ACE index suggests that the recent maxima are not that much different from the maxima of the 50's and 60's. As described above the PDI plot shows a recent maximum substantially greater than any previous.

If we ignore the pre-1973 figures, we get an expected result in that we have seen an increase over the years since. I say 'expected' because it falls into the pattern of previously observed and described oscillations in activity.

Because theory suggests that the increase in SSTs should have only caused an increase in PDI relatively small to that observed, it seems to me that there are two possibilities. Either 1. Theory is grossly wrong on that point or 2. There are other things going on.

I would think that the 'other things going on' are part of the oscillations in activity observed over the years. While an increase in SSTs may be causing a slight increase in the intensity, it seems that the other changes that occur over the cycle far outweigh that of the temperatures.