Skip to comments.Global Warming Kicked 2005 Hurricanes Up A Notch
Posted on 06/27/2006 9:34:22 AM PDT by cogitator
BOULDER, Colorado, June 26, 2006 (ENS) - Global warming created about half the extra warmth in the waters of the tropical North Atlantic that stimulated hurricane formation in 2005, while natural cycles were a minor factor, a new study from the National Center for Atmospheric Research demonstrates.
The research by world leading climate scientists contradicts recent claims that natural cycles are responsible for the increase in Atlantic hurricane activity since 1995 and adds support to the theory that hurricane seasons will become more active as global temperatures rise.
While researchers agree that the warming waters fueled hurricane intensity, they have been uncertain whether Atlantic waters have heated up because of a natural, decades-long cycle, or because of global warming.
The new analysis by lead author Dr. Kevin Trenberth and associate scientist Dennis Shea of the National Center for Atmospheric Research (NCAR) will appear in the June 27 issue of "Geophysical Research Letters," published by the American Geophysical Union.
"The global warming influence provides a new background level that increases the risk of future enhancements in hurricane activity," says Trenberth, who heads NCAR's Climate Analysis Section.
Last year produced a record 28 tropical storms and hurricanes in the Atlantic. Hurricanes Katrina, Rita, and Wilma all reached Category 5 strength, the highest level on the Saffir-Simpson Hurricane Scale. Category 5 hurricanes carry winds greater than 155 mph (249 km/hr). The storm surge is greater than 18 feet (5.5 meters) above normal.
This year the National Weather Service Climate Prediction Center forecasts a "very active" season, with 13-16 named storms, 8-10 hurricanes, and 4-6 major hurricanes.
The 2006 prediction indicates a continuation of above-normal Atlantic activity that began in 1995, but forecasters say they do not currently expect a repeat of last years record season.
Trenberth and Shea's research focuses on an increase in ocean temperatures.
During much of last year's hurricane season, sea-surface temperatures across the tropical Atlantic between 10 and 20 degrees north, where many Atlantic hurricanes originate, were a record 1.7 degrees Fahrenheit above the 1901-1970 average.
By analyzing worldwide data on sea-surface temperatures since the early 20th century, Trenberth and Shea were able to calculate the causes of the increased temperatures in the tropical North Atlantic.
Their calculations show that global warming explained about 0.8 degrees F of this temperature rise.
Aftereffects from the 2004-05 El Nino accounted for about 0.4 degrees F.
The Atlantic multidecadal oscillation (AMO), a 60 to 80-year natural cycle in sea-surface temperatures, explained less than 0.2 degrees F of the rise, Trenberth says.
The remainder is due to year-to-year variability in temperatures.
Earlier studies have attributed the warming and cooling patterns of North Atlantic ocean temperatures in the 20th century - and associated hurricane activity - to the Atlantic multidecadal oscillation.
But Trenberth, suspecting that global warming is also playing a role, looked beyond the Atlantic to temperature patterns throughout Earth's tropical and midlatitude waters.
He subtracted the global trend from the irregular Atlantic temperatures - separating global warming from the Atlantic natural cycle.
The results show that the AMO is weaker now than it was in the 1950s, when Atlantic hurricanes were also active.
However, the AMO did contribute to the lull in hurricane activity from about 1970 to 1990 in the Atlantic.
Global warming does not guarantee that each year will set records for hurricanes, according to Trenberth. He notes that last year's activity was related to very favorable upper-level winds as well as the extremely warm sea-surface temperatures.
Trenberth says each year will bring ups and downs in tropical Atlantic sea-surface temperatures due to natural variations, such as the presence or absence of El Nino, a warming pattern in the tropical Pacific Ocean.
Still, the researchers conclude that over the long-term ocean warming will raise the baseline of hurricane activity.
There is an assumption here that Global Warming is one thing, and "natural cycles" are another thing. I need to read no further.
There. I fixed it.
The .edu on the end of the URL says it all.
Nothing to see here, move along.
And Dr. William Gray, who is the preeminent hurricane expert in this country, has said that so called global warming has nothing to do with Atlantic hurricanes.
"Global warming" is generally used to indicate the warming of the globe that has occurred since the mid-1800s. There is considerable scientific evidence that this warming, particularly the warming which occurred in the late 1980s into the 1990s and to present, has been augmented by human activities, particularly those that add CO2 to the atmosphere. CO2 concentration in the atmosphere has increased about 100 ppm since the mid-1800s, and this is about 100 ppm higher than the natural maximum over the past 640,000 years, as determined from measurements of CO2 in ice core bubbles.
Feel free to continue thinking that global warming is entirely natural. The scientific data does not support that line of thinking.
If you're happy with it, then I won't attempt to disturb your mindset.
It was the last time it happened.
Dr. Gray is not an oceanographer, and some of his ideas about oceanography are pretty clearly wrong.
Now, this article doesn't directly address what Dr. Gray knows about hurricanes. But the new study just came out, and requires evaluation. Dr. Gray's evaluation will be one of many.
Please explain for the class how the Vikings made the world warm, how the Pilgrim caused things to get cold, and how Abe Lincoln managed to heat things up again.
It's a natural cycle.
And I'll bet the CO2 in ice core bubbles doesn't degrade one little bit being in contact with all that frozen and often liquid H2O for all that millenia, no sirree. Can you insure that those ice cores came from glaciers in which no liquid water occured in the time the CO2 was trapped?
... which causes cooling. Every model I have looked at shows that concentrated convection causes cooling. The subsidence around hurricanes cools and is much larger than the hurricane itself. Another factor is that tropical convection (not just hurricanes) peaks at night and therefore so do the cold cloud tops which warm the planet. There are probably other factors, but basically this increase in storminess is a sure sign of negative feedback from warming oceans.
Not one hurricane hit Florida from 1952 to 1962, a period of high water temperature the study references.
Higher water temps alone are not reliable predictors of frequency or severity.
Subtracting higher water temperatures elsewhere from the measured data guarantees the remaining increase will not be attributable to the rest of the factors the study includes.
What sort of science is this?
All of the effects that you mention have been evaluated. The current warming trend is being augmented by the increasing concentration of CO2 in the atmosphere. Natural variability cannot account for all of the observed warming.
I can back up all of these statements with references to scientific literature, if you would be willing to consider what they say. From long experience, I know that this effort is usually fruitless for someone who already has their mind made up. Tell me if you're actually interested -- I won't waste my time or yours if you aren't.
Why should it degrade? The ice cores are from Greenland or Antarctic ice caps. If you want to know more, try searching on the subject. I have extreme confidence that the CO2 concentrations measured in ice core bubbles are accurate, because they've been independently determined from more than one ice core.
Atmospheric or oceanic surface cooling?
We can just agree to disagree, since I consider that scientific literature to be agenda-driven crap. I grant that temperatures are rising. I grant that CO2 levels are rising. I laugh at the idea that humans are changing the global climate.
Does that indicate that the 1950s weren't an active hurricane period? It can be an active period and yet still spare Florida.
Higher water temps alone are not reliable predictors of frequency or severity.
What sort of science is this?
Published. It's in Geophysical Research Letters.
Not completely sure but probably oceanic surface from the lack of clouds. The other effect is the removal of water vapor from the upper troposphere reducing the atmospheric warming.
Fine with me, but I wonder why you would think that a 100 ppm increase in global atmospheric CO2 concentrations would have no significant effects at all.
I probably didn't quite get your point. I asked because hurricane winds do cool the surface ocean due to mixing. There was an event a couple of years ago when one hurricane hit the cooler "wake" of a previous hurricane and lost significant strength over the cooler waters. But I think your point was about something else.
Accurate as far as I can tell to a century or in timescale. Comparing any past century averages to the past centuries increase does not provide a lot of data points. Comparing ice cores to CO2 measurements made other ways like in the atmosphere is silly.
Mixing cooler water to the surface doesn't change the earth's energy balance. BUt concentrated convection does do that by suppressing wider convection and high clouds, less upper atmospheric water vapor, etc.
On second thought, it could lower the amount of heat radiated to space and warm the earth overall. I'm not sure how much, something to research.
I completely disagree.
I'm not sure what DE08 and DSS are, but all of the other points are from ice cores. The black line is the Mauna Loa atmospheric CO2 measurement curve.
This figure shows it a little better. There's another better one that I can't seem to find at the moment.
Exactly. They insist -- dishonestly -- that it's a given that man causes global warming.
Your pictures are highly deceptive. They imply ice core resolution that is simply impossible in any sample other than a modern (uncompacted) one. The first one overlays measurements so you can't even see if there any ice measurements underneath (not that they matter). The second is pretty lacking, I'm sure you can find better. In the meantime, here's a better source, showing error bars on most of the samples. Note the absence of a hockey stick.
I have a couple of problems with this. One, none of the "global warming" theories explains why Mars' polar caps are melting nor why the storms on Saturn have become more intense. To date, neither astronomers nor skulking by the Hubble telescope have shown any evidence of either SUVs or humans on Mars.
Also, Dr. Sallie Baliunas explains that of the 11 gases that comprise the so-called "Greenhouse Gases", we understand the influences of fewer than half, including CO2. And, of the gases that we DO understand, we still don't fully understand how they interact or affect the earth's environment.
It's not a surprise that ice core CO2 data from older periods has decreased temporal resolution. But the concentrations of CO2 measured in the bubbles are accurate.
Where's your figure? Here's another one (with error bars; this might be the one you were planning to post):
Now that we've seen it three times, I guess we understand it. ;-)
The last one is not a scientific analysis, I have studied the (woefully inadequate) Mars temperature data and see no global warming or cooling. I believe the ice cap melting is, most likely, a local effect.
I don't know about Saturn; read this about Mars:
Also, Dr. Sallie Baliunas explains that of the 11 gases that comprise the so-called "Greenhouse Gases", we understand the influences of fewer than half, including CO2.
The statements of Dr. Baliunas, an accomplished scientist and also a noted climate change skeptic, should be compared to the mainstream scientific opinion.
I agree that a complete and thorough determination is still a way off.
My two postings beats your single posting.
It is my understanding that increasing CO2 in the atmosphere reaches a saturation point, a point that after which you can add all the CO2 you like to the atmosphere and it will not increase temperatures any further. It is my understanding that the maximum warming that could occur with additional CO2 is about 1 degree celsius. You could take CO2 all the way to 6000ppm at which point it would become letahl to humans and you would still only have the one degree of warming.
Correct me if I am wrong, but I don't believe I am.
Byrd station is not the GISP or Vostok CO2 data. The small figure below kinda shows how the Vostok record splices into the modern era. Essentially when CO2 rose at the end of the last glacial period, it went up to ~280 ppm, and that's where it stayed until the slight rise began in the mid-1700s/early 1800s.
Let's see... Global warming caused "about half". How much does that leave for "natural cycles"? I think I can handle the math. It would be "about half". Somehow the "about half" caused by natural cycles is a "minor factor" but the "about half" caused by presumed global warming is something very significant.
If it wasn't for the dire consequences of governments acting on such nonsense, the obvious bias of this article would be amusing.
I want them to tell me why it is 82 degrees here today. In all my life in NM there has never been an 82 day in summer w/o rain and heavy cloud cover. The sun is shining and it's quite cool out there, it should be 99 or 100 degrees by now.
"Splicing" (as with the temp hockey stick) is not valid science without showing natural variation in the older data (which you can't with ice cores since they average CO2 for a mininum of 30 years). The second problem is the Byrd station data is ludicrously cut off before it reached 285ppm +/- 10ppm about 10k years ago. Obviously a picture with an agenda.
Wellllllllll, what ya got right there is evidence of Global Warming. Anytime you see unusually cold temperatures, that's a sure sign that the Earth is heatin' up. Now, as your summer progresses, you may see temperatures increase -- perhaps even going over 100! That's to be expected in this time of Global Warming. Now, if the temperature where you are stays at about 82 all summer long, I want you to contact the government, because that would a very unnatural development, and a sure since that Global Warming has increased ...
"Global warming created about half the extra warmth..."
If Global Warming is the result of solar heat retained by the planet through the increased concentration of specific atmospheric gases generated by the irresponsible combustion of carbon dioxide releasing fuels, then how can this same result be responsible for creating extra warmth? Global Warming is an end result that may have further consequences, but it can't, in and of itself, create energy in the form of extra warmth. Could this be an example of circular logic rather than factual reporting?
I've seen this aspect mentioned frequently, and this is a skeptical "talking point". My understanding is that this is a misapprehension of how CO2 energy absorption and re-radiation actually takes place. Below is the IPCC's short-and-simple statement:
"It has been suggested that the absorption by CO2 is already saturated so that an increase would have no effect. This, however, is not the case. Carbon dioxide absorbs infrared radiation in the middle of its 15 mm band to the extent that radiation in the middle of this band cannot escape unimpeded: this absorption is saturated. This, however, is not the case for the bands wings. It is because of these effects of partial saturation that the radiative forcing is not proportional to the increase in the carbon dioxide concentration but shows a logarithmic dependence. Every further doubling adds an additional 4 Wm-2 to the radiative forcing."
The whole piece is bad. See post #39 for William Tell's good observation on the significance of Global Warming creating "about half" of the warmth.
Rather than discuss the physics, the authors imply that the CO2 itself will warm the air 2C. But their method obviously includes feedback, so it's not the CO2 doing the warming it's the water vapor in an uncertain and poorly modeled weather model.
Rats! I was planning to release a book proving that the SUN is responsible for heating the oceans and planet.
"I wonder what these ass-clowns will say if the Cane season comes out to be less active than first predicted? Oh, I know. They will have forgotten they made this prediction."
They have already covered their asses in the above original post....Global Warming does not guarantee that every season will be abnormally high....blah blah blah
But over time the baseline will increase due to global warming....blah blah blah
That's how they cover their ass, they can still be wrong for the next ten years or whatever, but they insist the long term (decades or centuries?) will prove them correct.
Maybe so. But the key point I've made (numerous times) is that the maximum natural peak in atmospheric CO2 concentrations, over the past 640,000 years now with the EPICA core, is about 280 ppm (I'll accept +/- 10 ppm error). No matter how the core data is sliced/spliced/or diced, that is a salient fact. The more modern ice core data (Siple or Taylor or Law) starts there and then shows the increasing CO2 concentration commencing in the 1700s, and merging quite smoothly into the Mauna Loa measurements.
And it's not like we didn't know burning wood and kerosene and oil and gas would put CO2 into the atmosphere; so it shouldn't come as much of a surprise that atmospheric samples confirm that.
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