Dean = Global Warming?

[terstorm1012]

well it all boils down to:

No singular event can be attributed to global warming as weather does not equal climate.

[Jim Hughes]

This activity level is not GW related and I could show a relationship between the stratosphere and the most strongest ATL hurricanes.

[MGC]

I think this recent rash of Cat-5's can be attribited to better data. We did not have this kind of data available before the 1970's. We really didn't have that great of satellite data in the 60's. In the 50's aircraft recon was just starting. Unless a system hit land at a certain intensity or a ship had the misfortune of finding itself in the eye of a severe hurricane and surviving then we got little data. The Galveston hurricane of 1900 had one weather observation taken and that was at lanfall. Could it have reached a higher intensity out over the loop current before hitting land? Dean was an extremely rare event, a Cat-5 at landfall. I don't think hurricanes are sudenly becoming more powerful. We are just getting better at detecting these extreme intensities......MGC

[x-y-no]

Is anyone willing to take a crack at my question?

[Downdraft]

Is anyone willing to take a crack at my question?

I think your asking one of those $64,000 questions that with the data we have can't be answered at the moment.
For instance can we say because of global warming we have increased SAL a cyclone inhibitor or can we say warmer Pacific greater El Nino events also an Atlantic basin hurricane inhibitor. What about changes in salinity from melting polar ice? Salinity content affects water evaporation. How does the ocean's temperature affect the Atlantic ridge? What about the increased numbers of ULL's the last two years, any relation? We can make an argument that some of the factors will decrease hurricane frequency but those that do form will be stronger. I don't think there is any doubt GW is happening. How much of it is made by man and how much is natural planetary occurrence is a good debate. I'm still saying Dean is not a good example because it stayed in the tropics where ocean temperatures are always high.

[opera ghost]

How would Dean's landfall have been recorded 100 years ago?

A monster of a storm, obviously, but it hit a somewhat less densely populated area and for all that we *know* that it was a category 5 with incredible winds- it also didn't level the cities it hit. Yes it was terrible, and yes it was bad- but compared to it coming inland in a major metropolitan area it was lucky. Without the ability to scientifically measure the winds and see the system from space- what would we have classed Dean as, retrospectively, especially with Katrina still on peoples minds as how horrific a storm can be?

As much as I worry about the safety of life and limb of the people affected, Dean was no 1900 (a category4). Indianola? Category4. Mitch? No. It wasn't an Andrew or a Katrina. How many category 5 hurricanes pre-1950 did we simply not record because the coast they hit was so sparsely inhabited and their track didn't cross major shipping lines when there was a ship present? How many storms do we consider weak due to a lack of lives or property lost that were "lucky"?

The lack of scientific data makes normalcy over hundreds of years difficult to judge. We know there was a super active period in the 50's, and we're currently in a super active period now. Were they both flukes- global warming in action? Or have there been other super active times that the natives didn't record? Tiny ocean front communities- already somewhat cut off from a bigger society- lost to the sea?

I think it's significant that we're in an active period- but looking at the history of hurricanes, a pair of active period in 100 years makes the kind of time frame we have to work with much more difficult to judge. Are they flukes or do we just lack the data to be able to say, hey we've had significant activity increases every 50-75 years for the last 500 years, no surprise! I can't prove it either way- no one can.

[chrisnnavarre]

Well, if we have maybe two or three more Katrina and Ivan situations along the Gulf coast then I think maybe someone should start thinking we have a problem.

Global warming or not I really do belive that the population along the coastlines of the U.S. are going to start migrating inland if these types of catastrophies continue.

[ohiostorm]

Is there a list out there of the top 10 strongest by wind speed?

[terstorm1012]

The lack of scientific data makes normalcy over hundreds of years difficult to judge. We know there was a super active period in the 50's, and we're currently in a super active period now. Were they both flukes- global warming in action? Or have there been other super active times that the natives didn't record? Tiny ocean front communities- already somewhat cut off from a bigger society- lost to the sea?

I think it's significant that we're in an active period- but looking at the history of hurricanes, a pair of active period in 100 years makes the kind of time frame we have to work with much more difficult to judge. Are they flukes or do we just lack the data to be able to say, hey we've had significant activity increases every 50-75 years for the last 500 years, no surprise! I can't prove it either way- no one can.

For your last part, not sure if it can be said for the Atlantic Basin but it's certainly been observed in the Western Pacific. Infer from that what you will.

http://adsabs.harvard.edu/abs/2000IJCli..20..183C

[x-y-no]

Is anyone willing to take a crack at my question?

I think your asking one of those $64,000 questions that with the data we have can't be answered at the moment.
For instance can we say because of global warming we have increased SAL a cyclone inhibitor or can we say warmer Pacific greater El Nino events also an Atlantic basin hurricane inhibitor. What about changes in salinity from melting polar ice? Salinity content affects water evaporation. How does the ocean's temperature affect the Atlantic ridge? What about the increased numbers of ULL's the last two years, any relation? We can make an argument that some of the factors will decrease hurricane frequency but those that do form will be stronger.

Fair enough, and these are all things I've speculated about myself. But what really perplexes me is how anyone can state with confidence (as many do) that global warming does not increase the intensity of cyclones when the only evidence we have (warmer climate leads to greater oceanic heat content and oceanic heat content is known to contribute to cyclone intensity, plus the admittedly problematic statistical evidence) indicates that it does.

In other words, why dismiss a physically sensible hypothesis with at least some empirical support for a nebulous hypothesis involving some unknown countervailing force? What's the basis for doing that other than personal preference?

I don't think there is any doubt GW is happening. How much of it is made by man and how much is natural planetary occurrence is a good debate.

Hmmm ... I can live with that statement. I think the evidence is quite strong for a large anthropogenic component but lets leave that for another day since it's a side-issue to the topic of this thread.

I'm still saying Dean is not a good example because it stayed in the tropics where ocean temperatures are always high.

I'd agree that Dean is not a good example, but for the more basic reason that no single weather event can ever be conclusively tied to global warming, at least until we get into the realm of the truly unprecedented (something unlikely to happen).

[Downdraft]

I'm with you X-Y all the way. The evidence of warming is overwhelming the factors that have contributed to it are a debate for another day. My personal fear is two-fold. First, in our arrogance we attempt to modify that which we do not totally understand and then really let the Genie out the bottle. Second, as it regards hurricane intensities we don't wake up until we have an event of such magnitude that it defies what we would normally would accept in meteorology as natural. The debate that we have insufficient data is becoming a cop-out in a sense. Stronger hurricanes are now a fact and to dismiss there occurrence as we "probably" had them all long just couldn't measure them doesn't make that much sense to me. While most storms exist to mitigate the instability that caused them hurricanes exist to cool ocean waters. It makes total sense that the hotter the waters become the stronger the hurricanes become to cool them. In my lifetime major hurricanes were rare and cat 5's even rarer in the Atlantic Basin. Now it seems every year we've come to expect at least one to develop. That to me suggests a major change somewhere and we need to figure out why through science not passion.

[Derek Ortt]

higher SST can leader to warmer atmospheric temps, which increases atmospheric stability. You need cold air over warm SST to get a very unstable atmosphere

[benny]

A question for those who think there is no connection between global warming and more intense cyclones:

Since oceanic heat content is a well-understood contributor to cyclone intensity and a warmer climate clearly leads to higher average oceanic heat content, there must be some other effect of global warming which counteracts this if there is to be no enhancement of cyclone intensity.

What is this effect and what evidence is there to support it?

It would be the warming of the troposphere in general. If SSTs are rising but upper troposphere temperatures are rising too, there is no net increase in instability. There is some evidence of this but the lower levels seem to be warming more than the upper levels, for now.

[x-y-no]

higher SST can leader to warmer atmospheric temps, which increases atmospheric stability. You need cold air over warm SST to get a very unstable atmosphere

I can see how that argument would apply to cyclogenesis (and indeed the empirical evidence seems to support the notion that GW does not lead to more cyclones) but surely that's not an issue once one already has a tropical system?

[Sanibel]

I forget the names, but I read an article saying that the warming troposphere claims hypothesized by a certain scientist are now coming true. Forgive my lack of reference. It would be speculation, but this could explain why other basins are not seeing increased activity.

The balance would tilt towards GW if Atlantic Oscillation negative periods became active with more high intensity cyclones.

Has anyone ever considered if these huge man-made amounts of CO2 induced a natural cycle that is then exacerbated by the additional man-made component?

[Downdraft]

higher SST can leader to warmer atmospheric temps, which increases atmospheric stability. You need cold air over warm SST to get a very unstable atmosphere

I can see how that argument would apply to cyclogenesis (and indeed the empirical evidence seems to support the notion that GW does not lead to more cyclones) but surely that's not an issue once one already has a tropical system?

Which brings us all the way back to the reason for the thread to begin with. If your using intensity figures to support your hypothesis about global warming you can't use Dean as a good example considering it's location, track and the fact it never left tropical waters. I still say you can make a sound argument that GW would actually limit hurricane frequency but conversely intensity of hurricanes might very well increase. Both views have sound logic to support them.

[wxwatcher91]

Some research to read:

Peter Webster in "Science"
Kerry Emanuel in "Nature"
William Gray in his Summary of the 2005 Hurricane Season.

Sorry, but I dont have links for these right now. Try google for now lol.

[x-y-no]

Which brings us all the way back to the reason for the thread to begin with. If your using intensity figures to support your hypothesis about global warming you can't use Dean as a good example considering it's location, track and the fact it never left tropical waters.

I'm not very clear on what you're arguing here. I agree that no single weather event can be attributed to global warming and obviously this includes Dean. But that's not a matter of where the storm tracked, rather it's a fundamental principle.

So are you arguing something more, such as that storms which never leave the tropics shouldn't be used in compiling annual total global ACE for the purpose of determining any trend relating to global warming? If so, I can't agree.

I still say you can make a sound argument that GW would actually limit hurricane frequency but conversely intensity of hurricanes might very well increase. Both views have sound logic to support them.

That's pretty close to my working hypothesis.

[Ed Mahmoud]

2 days ago NYC tied their all time coldest August daytime mex temps at 59ºF, and I don't think that implies a glaciation episode is about to occur.

[Derek Ortt]

GW could lead to more enhanced TCs

However, if the tropics heat up faster than the poles, thermal wind balance would imply greater wind shear. That may confine TCs to the tropics where the horizontal temperature gradients are less