Global warming and the frequency of intense Atlantic hurricanes: model results
Could global warming increase wind shear over the Atlantic, potentially leading to a decrease in the frequency of Atlantic hurricanes? There is a growing consensus among hurricane scientists that this is indeed quite possible. Two recent studies, by Zhao et al. (2009), "Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM", and by Knutson et al. (2008), "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", found that global warming might increase wind shear over the Atlantic by the end of the century, resulting in a decrease in the number of Atlantic hurricanes. For example, the second study took 18 relatively coarse (>60 km grid size) models used to formulate the 2007 IPCC climate report, and "downscaled" them using a higher-resolution (18 km grid size) model called ZETAC that was able to successfully simulate the frequencies of hurricanes over the past 50 years. When the 18 km ZETAC model was driven using the climate conditions we expect in 2100, as output by the 18 IPCC models, the authors found that a reduction of Atlantic tropical storms by 27% and hurricanes by 18% by the end of the century resulted. An important reason that their model predicted a decrease in the frequency of Atlantic hurricanes was due to a predicted increase in wind shear. As I explain in my wind shear tutorial, a large change of wind speed with height over a hurricane creates a shearing force that tends to tear the storm apart. The amount of wind shear is critical in determining whether a hurricane can form or survive.
Figure 1. Top: predicted change by 2100 in wind shear (in meters per second per degree C of warming--multiply by two to get mph) as predicted by summing the predictions of 18 climate models. Bottom: The number of models that predict the effect shown in the top image. The dots show the locations where tropical storms formed between 1981-2005. The box indicates a region of frequent hurricane formation where wind shear is not predicted to change much. Image credit: Geophysical Research Letters, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", by Vecchi and Soden, 2007.
Since the Knutson et al. study using the 18 km resolution ZETAC model was not detailed enough to look at what might happen to major Category 3 and stronger hurricanes, a new study using a higher resolution model was needed. This was done by a team of modelers led by Dr. Morris Bender of NOAA's GFDL laboratory, who published their results in Science in February. The authors used the GFDL hurricane model--the model that has been our best-performing operation hurricane track forecasting model over the past five years--to perform their study. The GFDL hurricane model runs at a resolution of 9 km, which is detailed enough to make accurate simulations of major hurricanes. The researchers did a double downscaling study, where they first took the forecast atmospheric and oceanic conditions at generated by the coarse (>60 km grid) IPCC models, used these data to initialize the finer resolution 18 km ZETAC model, then used the output from the ZETAC model to initialize the high-resolution GFDL hurricane model. The final results of this "double downscaling" study suggest that although the total number of hurricanes is expected to decrease by the end of the century, we should expect an increase of 81% in the number of Category 4 and 5 storms in the Atlantic. This trend should not be clearly detectable until about 60 years from now, given a scenario in which CO2 doubles by 2100. The authors say that their model predicts that there should already have been a 20% increase in the number of Category 4 and 5 storms since the 1940s, given the approximate 0.5°C warming of the tropical Atlantic during that period. This trend is too small to be detectable, given the high natural variability and the difficulty we've had accurately measuring the exact strength of intense hurricanes before the 1980s.The region of the Atlantic expected to see the greatest increase in Category 4 and 5 storms by the year 2100 is over the Bahama Islands (Figure 2), since wind shear is not expected to increase in this region, and sea surface temperatures and atmospheric instability are expected to increase there.
The net effect of a decrease in total number of hurricanes but an increase in the strongest hurricanes should cause an increase in U.S. hurricane damages of about 30% by the end of the century, the authors compute, assuming that hurricane damages behave as they did during the past century. Over the past century, Category 4 and 5 hurricanes made up only 6% of all U.S. landfalls, but accounted for 48% of all U.S. damage (if normalized to account for increases in U.S. population and wealth, Pielke et al., 2008.)
Figure 2. Expected change in Atlantic Category 4 and 5 hurricane per decade expected by the year 2100, accord to the Science paper by Bender et al. (2010).
Commentary
These results seem reasonable, since the models in question have been successfully been able to simulate the behavior of hurricanes over the past 50 years. However, the uncertainties are high and lot more research needs to be done before we can be confident of the results. Not all of the IPCC models predict an increase in wind shear over the tropical Atlantic by 2100, so the increase in Category 4 and 5 hurricanes could be much greater. Also, the GFDL model was observed to under-predict the strength of intense hurricanes in the current climate, so it may not be creating enough Category 4 and 5 hurricanes in the future climate of 2100. On the other hand, IPCC models such as the UKMO-HadCM3 predict a very large increase in wind shear, leading to a drastic reduction in all hurricanes in the Atlantic by 2100, including Category 4 and 5 storms. So Category 4 and 5 hurricane frequency could easily be much greater or much less than the 81% increase by 2100 found by Bender et al.
The estimates of a 30% increase in hurricane damages by 2100 may be considerably too low, since this estimate assumes that sea level rise will continue at the same pace as was observed in the 20th century. Sea level rise has accelerated since the 1990s, and it is likely that this century we will see much more than than the 7 inches of global sea level rise that was observed last century. Higher sea level rise rates will sharply increase the damages due to storm surge, which account for a large amount of the damage from intense Category 4 and 5 hurricanes.
Keep in mind that while a 30% in hurricane damage by the end of the century is significant, this will not be the main reason hurricane damages will increase this century. Hurricane damages are currently doubling every ten years, according to Pielke et al., 2008. This is primarily due to the increasing population along the coast and increased wealth of the population. The authors theorize that the Great Miami Hurricane of 1926, a Category 4 monster that made a direct hit on Miami Beach, would have caused about $150 billion in damage had it hit in 2005. By 2015, the authors expect the same hurricane would do $300 billion in damage. This number would increase to $600 billion by 2025 (though I think it is likely that the recent recession may delay this damage total a few years into the future.) It is essential that we limit coastal development in vulnerable coastal areas, particularly along barrier islands, to reduce some of the astronomical price tags hurricanes are going to be causing. Adoption and enforcement of strict building standards is also a must.
The authors of the GFDL hurricane model study have put together a nice web page with links to the paper and some detailed non-technical explanations of the paper.
References
Bender et al., 2010, "Modeled Impact of Anthropogenic Warming on the Frequency of Intense Atlantic Hurricanes", Science, 22 January 2010: Vol. 327. no. 5964, pp. 454 - 458 DOI: 10.1126/science.1180568.
Vecchi, G.A., B.J. Soden, A.T. Wittenberg, I.M. Held, A. Leetmaa, and M.J. Harrison, 2006, "Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing", Nature, 441(7089), 73-76.
Vecchi, G.A., and B.J. Soden, 2007, "Increased Tropical Atlantic Wind Shear in Model Projections of Global Warming", Geophysical Research Letters, 34, L08702, doi:10.1029/2006GL028905, 2007.
Jeff Masters
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just thought I'd stop by and read up from today.
anyway, have a great rest of the night.
40.42°N 86.91°W (Elev. 604 ft)
WEST LAFAYETTE, Ind. - A team of Purdue University students has turned an undergraduate design project into a sturdy, portable, spacious, easily assembled shelter for homeless families suffering in the aftermath of disasters like the earthquake in Haiti.
Rafael Smith's Uber Shelter packs nearly 200 square feet of living space in a multi-tiered shelter. Smith, an industrial design graduate from Purdue's College of Liberal Arts, said the shelter would be perfect for people huddled under sheets or mired in the swampy camps into which hundreds of thousands of Haitians are crammed.
"Uber Shelter gives a dignified temporary home to people enduring crisis," Smith said. "The stilt system gets people well above the sewage, mud, rubbish, insects, snakes, rodents and parasites that plague these victims around the world."
Smith, now working in Chicago, won an International Design Excellence Award and then kudos from The New York Times for a shelter that can be easily transported to disaster areas and erected with just two wrenches. It covers a small footprint, provides standing room and privacy, and is made of recyclable materials. Shipping in a 4 foot by 8 foot by 2 foot package, the stilted shelter can be built on hillsides, a useful capability in crowded, steep terrain like that in Port au Prince.
"Putting one's education quickly to work to immediately improve the lives of millions of the most desperate people in the world is an absolute dream come true," said Purdue engineering graduate student Josh Messmer, who helped Smith design the prototype and continues to tweak it to make it stronger, safer, lighter and more affordable.
Since erecting the prototype in his parents' Indianapolis horse pasture in November, Smith has received thousands of dollars in online donations to help bring Uber Shelter to those who need it. Investors have called from New York, and aid agencies on the ground in Haiti have inquired about purchasing thousands of units as a season of torrential rain bears down on those victims.
"We're looking for partners who are as committed as we are to helping destitute people," said Brad Milius, a Purdue management alumnus who serves as the Uber Shelter Project development director while pursuing a graduate degree in nonprofit management at Indiana University-Purdue University Indianapolis.
Smith was recently selected to attend the Unreasonable Institute, a "boot camp" where he will be trained and mentored by a large team of fellow humanitarian-minded entrepreneurs. There in Boulder, Colo., Smith will present Uber Shelter to scores of angel investors.
"This is not a profit-making endeavor for me," Smith said. "My business model must have the lowest possible overhead to make it as affordable as possible to the millions of people who need this shelter around the world in places like Haiti, Darfur, Chile, China, Taiwan and Turkey."
Uber Shelter has already survived 60 mph winds and a snowy Indiana winter. Smith will live in the shelter intermittently until he travels to Colorado this summer for the institute. While living in the shelter, Smith will seek ways to further improve its ergonomics, portability, durability and cost.
"This shelter is vastly superior to a tent, but I won't be completely satisfied until it comes even closer to or surpasses a tent's cost," he said.
Writer: Jim Schenke, 765-494-6262, jschenke@purdue.edu
Yup and we will analize it to death.....I read Klotzbach's MJO-Atl Hurricane Relationship article last night....A very good read with some pretty impressive correlations between the MJO cycles and "cluster" of storms in any given season.......Gonna keep a close eye on that MJO this year, particularly, in the early part of the Season.
thats awesome, are they anywhere near mass producing them cheaply?
http://nsidc.org/arcticseaicenews/2010/040610.html
"April 6, 2010
Cold snap causes late-season growth spurt
Arctic sea ice reached its maximum extent for the year on March 31 at 15.25 million square kilometers (5.89 million square miles). This was the latest date for the maximum Arctic sea ice extent since the start of the satellite record in 1979."
Edit __
1010- BTW, if interested, the powerpoint presentation from the CSU folks at the Hurricane conference in Orlando is embedded in this article.
National Hurricane Conference sparks renewed interest in global warming debate
OOOPS wrong button, sorry :)
Thank You.........We would all be back in the stone age (watching trees start to sway and figuring "somethng" is a brewing) without the Internet and Satt Loops.... :)
Its not even raining in Macon :(
AOI
AOI
AOI
AOI
Humor in Comments
Lots of questions this morning.
Very cool uberstructure! Looks cool enough for the tropics, but was handeling the snow OK. It is great that it is raised. Were there platforms for the feet?
What is up with all the quakes? Are they triggering each other and can we expect a bump in volcanic eruptions or is this just fault stress relief?
Where can I get time series data for global cloud cover?
Seems a little odd to me that they are forecasting 4 majors, but only 10 major hurricane days. Thats only an average of 2.5 days of category 3 or higher for those 4 hurricanes.
Appears they just took the mean of their analog years.
I looked at that too, and it matches the long term averages of 2.3 and 5.
Is nrtiwlnvragn a Welsh name?
Finally a question on DocMaster's blog, that I can answer!!!
It stands for "northern eyewall never again"!!
Bonus points for Aqua!!!
Just seems a bit low, any one storm could remain Cat 3 or higher out in the open Atlantic for 4-5 days. Forecast seems reasonable given the expected conditions across the MDR, Caribbean, and Gulf this summer.
I am a Florida pioneer historian and often portray my G Great Grandfather in period..1883.(see my avatar) As a result, I often try to "think" in those terms.. living isolated with no communication that was current, no barometer, only my nose and eyes.
For Francis, it was easy to see there was something out there, we got pounded for days prior to landfall. But for Jeanne.. I remember standing on my dock at dawn sniffing the air thinking there is not a single clue to stop me from getting in my sailboat and making a journey. That day, it was after the noon hour before I saw and felt things that would have made me hesitate, but by then, I would have been on my way by nearly six hours. Wilma was the same, especially as the storm was coming from an uncommon direction.
It alters the way I look at weather if I put myself in his shoes. I covet pioneer hurricane stories and pay attention to Dr. Landsea's reevaluation project... HURDAT. History has been dramatically altered many times by hurricanes.
LOL
Its a made up acronym
Northern Eyewall Never Again - Andrew
wish I had a dime for every time I tried to pronounce it :)
awesome post.
South Florida StormWatch
(main site)
No kidding. You can get 40 of those into a 40' container if you pack them right, and the weight is ok. Figure 2-4 people per ubershelter, and with Portlight's plan for the 40'... One container's worth of shipping can provide 90-170 people with housing.
Thanks Orca. I see no reason to disagree with that, based on the warmer than average tropical atlantic temperatures and the abating el nino. Kind of feeling 16 though because of that random azores subtropical storm we seem to have every year now.
So true....We get so many ufologists etc., talking about the sudden departure of the Mayan Civilization in the Yucatan, and the "mystery" behind it.....It could well have been a Cat 5 strike 2000 years ago.
Thanks, nrt!
Next Post
The next post will probably be Wednesday, and will be a guest post, since I am on vacation this week (I'm going to go experience the weather underground in Mammoth Cave!)
Jeff Masters
There would be a sedimentary clue or two in the record,and there isnt.
Mayans calenders are still selling brisk,worldwide.
In 1883, Gramps was the Keeper of Biscayne House of Refuge, at that time the only structure on what we now call Miami Beach. He took the Superintendent to Titusville and I use that trip as a way to be anywhere I need to be from Titusville to Biscayne Bay for my presentation and be historically correct.
Thanks for the kind words Aquake!
3 days before Jeanne hit another less infected pine tree in my yard turned brown overnight along with a few others in the neighborhood. That left no doubt for me.
Saw some turn dead before Faye, Wilma & a TD.. So the pine beetles aren't the best judge of strength. It could make an interesting paper for someone in the field. Not sure if they are eating it up or boring deep to survive the storm.
What an interesting observation.. well, sadly, I bet we get to see if it repeats itself this year.. there is now another "watcher" :)
Hurricane Preparation 2010
2010 April 07 14:33:05 UTC
Magnitude 6.0
Date-Time Wednesday, April 07, 2010 at 14:33:05 UTC
Thursday, April 08, 2010 at 12:33:05 AM at epicenter
Time of Earthquake in other Time Zones
Location 3.863°S, 141.861°E
Depth 35 km (21.7 miles) set by location program
Region NEW GUINEA, PAPUA NEW GUINEA
Distances 145 km (90 miles) SSE of Vanimo, New Guinea, PNG
195 km (120 miles) SE of Jayapura, Papua, Indonesia
855 km (530 miles) NW of PORT MORESBY, Papua New Guinea
2865 km (1780 miles) NNW of BRISBANE, Queensland, Australia
Location Uncertainty horizontal +/- 9.8 km (6.1 miles); depth fixed by location program
Parameters NST= 44, Nph= 44, Dmin=847.9 km, Rmss=1.29 sec, Gp= 54°,
M-type=body wave magnitude (Mb), Version=6
Source USGS NEIC (WDCS-D)
Event ID us2010uubr
By "pine beetles", are you meaning Pine Bark Beetles?
We have them very badly here in Houston (thanks to the drought last summer), and they have been seen to kill a tree within 8 days.
ESL by LSU
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