Global Warming Intensifying Hurricane Activity?

[Mike Peregrine]

Not interested in restarting debate over the global warming issue, as the opinions seem to be as sharply divided in the scientific community as they are in our humble little chase forum here ... but I just read this article in USA Today concerning a recent study by climatologist Kerry Emanuel of MIT as it applies to the effects that global warming may play on hurricane development and intensity. Associated Press did a nice job of covering the basics of the dispute as well, so rather than bring up the same debate in here, my question has to do with the possibilities of even more localized effects on the mesoscale or even storm scale as it applies to supercell activity across the U.S. or elsewhere. Wondering if any climatologists might currently be involved in any projects along this line, as it seems reasonable to conclude that as synoptic scale features are modified as a result of the *possible* effects of global warming, this would in turn transfer and play a part in local activity as well. Has anyone read anything recently on the subject? Pretty interesting stuff to me, as it would certainly seem to possibly explain spring pattern irregularities seen over the last few years and point to the direction that chasing might be headed in the future ...

 

[Aaron Kennedy]

Emanuel is well known for his hurricane research... but I can't find his paper on AMS yet. Where is the original paper at?

Aaron

 

[Mike Peregrine]

Aaron - went back and took a look at the article, and found this quote:

Details of Emanuel's study appear Sunday in the online version of the journal Nature.

So I did a search on the Nature homepage and found this. The second link requires registration, but I'm sure it will have further details concerning the actual paper. May not be the link we're looking for, and might have to do some more poking around. Anyway, hope it helps - - -

 

[Douglas Mitchell]

I'm definitely no expert, but given that the average atmospheric temperatures has risen only about 2 degrees over X amount of years, and assuming that would translate to only a marginal oceanic temperature increase, that would definitely not explain the 50 percent increase in intensity.

 

[Justin Turcotte]

Assuming the GCMs and recent climate data in good order then the Arctic areas will warm the most significantly. This would tend to weaken the temperature gradient and the polar jet stream. This would be an inhibiting factor for supercells. This slackening of shear could conceivably be made up for by the warmer water temps fueling surface moisture flux. The death ridge in the summer should also be more potent. Kiss those summer Nebraska tors good-bye. Hello Winnipeg! My guess is using only the variables I mention, is that chase season would begin and end earlier. Maybe a prolonged second season in the fall.

 

[Bob Schafer]

There's a Reuters article from yesterday (7-31) which is a different writeup on Emanuel's study:

http://news.yahoo.com/s/nm/20050731/sc_nm/...TdmBHNlYwM3NTM-

Here's a snippet from that article:

"I have shown that they have become more destructive over the last 30 years. This particular hurricane energy measure is very well correlated with the surface temperature of the tropical oceans. That temperature has an upward trend. It has increased by about half a degree Centigrade over the last 50 years," Emanuel explained

I didn't see the 0.5C/50 years figure elsewhere. That's why I made this post.

Bob

 

[Morgan Palmer]

This is a fascinating discussion. I'm no expert either...

but while the talk about global warming perhaps affecting SSTs is interesting, if global temperatures increase just a small amount (few deg C) it would have a massive impact on polar ice masses. I would think tropical system climatology would be impacted in two ways.

1. a disruption (compared to current) of currents of warm and cool water. If certain ice sheets aren't there, then those currents would certainly be changed.

2. and I think this even greater an impact (justin hit on this)... since everything about weather is simply about the atmosphere trying to reach equilibrium, any warming that changes the coverage, latitude, and (possibly) the depth of those ice sheets/glaciers would, IMO, have a significant impact on the global and even synoptic air flow patterns. At the very least, cold surges wouldn't be quite as cold, and possibly subtropical systems that help distrubute heat could go farther north in latitude... etc.. etc... the dominoes start falling.

MP (no chicken little)

 

[Bill Tabor]

Not interested in restarting debate over the global warming issue, as the opinions seem to be as sharply divided in the scientific community as they are in our humble little chase forum here ... but I just read this article in USA Today concerning a recent study by climatologist Kerry Emanuel of MIT as it applies to the effects that global warming may play on hurricane development and intensity. Associated Press did a nice job of covering the basics of the dispute as well, so rather than bring up the same debate in here, my question has to do with the possibilities of even more localized effects on the mesoscale or even storm scale as it applies to supercell activity across the U.S. or elsewhere. Wondering if any climatologists might currently be involved in any projects along this line, as it seems reasonable to conclude that as synoptic scale features are modified as a result of the *possible* effects of global warming, this would in turn transfer and play a part in local activity as well. Has anyone read anything recently on the subject? Pretty interesting stuff to me, as it would certainly seem to possibly explain spring pattern irregularities seen over the last few years and point to the direction that chasing might be headed in the future ...

I'd say if you assume that global warming IS taking place as most agree and this affects ocean circulation and heating patterns - this in essence is part of the equation that creates weather. La Nina and El Nino are documented to produce certain general effects such as rainfall amounts in different geographic areas, timing, etc. Therefore obviously this means the synoptic scale is affected. If the synoptic scale and longwave pattern is affected along with perhaps blocking factors then no doubt this will influence where meso scale pertubations occur and therefore storm scale. In other words if you alter the foundation of weather making on the Earth then everything else is affected as a result of it in a dominoe effect as someone else alluded to.

I think the only real questions here is what those effects could be? It could limit, increase, or even neutralize storm intensity, distribution density, and location. That might make it difficult to determine the actual effect. It's a complicated system with negative feedback mechanisms. My guess is it will be tough to point to specifics on the meso or storm scale for individual cases. What you may notice though over a period of many years is a statistical trending toward different storm intensity, density distribution, and geographic location.

All that and most people are concerned with 'is it a man made problem'? While global warming is perhaps taking place,... from my reading this is part of a natural warmup cycle. It may be that man is accentuating or accelerating that cycle some. I believe we are probably a small lever in the scheme of things though. Large volcano eruptions can put vast quantities of greenhouse sulfur dioxide gas into the atmosphere and has many times in the past. This certainly affects global temperature and climate. Was watching a Yellowstone Supervolcano program recently. Fascinating. I believe it mentioned that if it erupted most of the global temperature could be reduced by 10 to 15 degrees for 3 to 5 years. That would kill the monsoon in tropical areas and lead to massive crop failure, starvation / death on a global magnitude. If you have a chance watch one of those programs - they are amazing. Yellowstone continues to percolate - biding it's time.

 

[cdcollura]

Warmin' it up a bit!

If global warming is the cause of the increased tropical activity, then we have a major problem.

There is still the possibility that the north atlantic current (NAO) can be causing the milder winters in the NE USA each winter and the increased hurricane activity in the tropics. Note that the Pacific side, is very quiet compared to the Atlantic.

Back in the 1980's I remember the E Pacific basin using the whole alphabet, now they barely make it to the "K" storm. Back in the period from the 1930's to the 1960's, hurricane activity was higher in the Atlantic.

Then it lulled from the 1970's to the 1990's (Andrew and Hugo being unlucky isolated events), then increased again from 1995 until present. The NAO is a 20-30 year cycle, and will "go away" as the cycle becomes opposed later. It's a long wait, but there is "light at the tunnel's end" for hurricane-haters.

Now global warming can be compared to the NAO just like comparing a bill of health from your doctor saying "You have AIDS" or "You're cholesterol is high", respectively. The global warming issue clearly is a "no cure" scenario, at least in our lifetimes.

This is because of petroleum and greenhouse gases from agriculture, transportation, and industry. It is a gobal-wide issue, and the USA is only rersponsible for a small portion of these CO2, methane, SO2, etc. emissions.

Central and South America often burns trash outdoors each day, I have seen many there doing it. Do that here in the US, and you will be arrested in most cases. To make things worse, the rain-forest there is being destroyed, fast. Trees are cleared, to make room for methane-producing cattle and farming. The trees are not only not replaced, but burned (slash-and-burn). In the US, trees are chopped down, but new ones are usually planted.

In Panama City (Panama), a thick haze is always in the sky. Normally, the deep tropics have a deep clean and blue sky. This is caused by the burning and deforestation in neighboring South America (Colombia, Brazil) causing smoke carried by the equilateral trade winds. Scares me since you can see the "mark" on the sky that way. You could smell it too. From the air, you cannot even see the ground unless you are on final approach into that part of the world.

In a more natural sense, there are lots of other things that can cause greenhouse gassing. CO2 and Methane are stored in the ocean and volcanic areas. A large release of such gasses is possible, and Methane is hundreds of times more potent at warming than CO2 is (don't fart!) ... Animals, such as cows and livestock, also create large amounts of methane.

The effects of global warming now, even scarier, are also from damage done several years or even decades ago too. Remember that gas guzzling smoking mustang your dad had when you were a kid?

Much research is being done on this issue to find and answer. Hopefully, it is the NAO cycle and not the latter, more grim, global-warming model.

Atlantic sea-surface temperatures this year of 2005 have been found to be as much as two (2) degrees above normal. This is why the Atlantic tropics have been so busy lately. Last year, 2004, was only one (1) degree above normal. Now, compare that to the Sci-Fi movie "day after tomorrow" where the temperature was 13 degrees off!