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.
"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.
Here's a man-made cloud from an ocean ship's smokestack, which cools the ocean surface. Man-made clouds are likely the key to managing the climate. The extra freshwater will encourage plant growth increasing CO2 consumption.
Not exactly. The core data shows error bars to 300ppm and the core data averages readings over 30 years to 50 years (mostly depending on the age of the sample). So there are blips of CO2 that got averaged out and it's essentially the same science as today's models (e.g. warming releasing CO2) to figure out how big those blips might be. It's not likely that any blip exceeds today's 380 ppm but I wouldn't rule it out either.
Could be. Natural clouds are probably the most important natural regulator. Weather modeling is woefully inadequate at the moment, but that will improve in the next few decades.
Hurricanes become powerful due to a lack of shear. I wonder how global warming caused that.
Nope. The problem is that you and the others ignore the variations in two ways: first in your incorrect prediction above. Second, more importantly, the variations this year affected the climate. It might now be warmer or colder because of this year's lack of Atlantic hurricanes. There is not much chance of it being insignificant.
So it must have cooled off in one year. LOL
Globally, yes. Atlantic and Gulf of Mexico SSTs were anomalously high in 2005. It will be interesting to see if the about-average, lower-than-predicted hurricane occurrence in 2006 has an effect on the climate (if in fact that could be examined); we'll still have to watch the current mild El Nino for signs of persistence. They usually don't keep going over the boreal summer.
North Atlantic SST animation June-August 2005 (includes anomalies)
North Atlantic SST animation Sept-Nov 2005 (includes anomalies)