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 in for a moment looking at the 'portents'.
SAL is in retreat, bigtime. A 'portent' in my book.
The new Tmobile Touch that was just released last weekend is unreal. It actually acts as a server for your laptop....UNREAL! You just have to search for the single. Gotta say this is better than an IPhone......better everything about it and its also Outlook friendly.
Record smashing heat-wave hits nation
Settle down, anti-science disinformers who try to shout down any talk of a link between climate change and extreme weather — these are only jokes. We all know that you can’t use a single weather event as evidence for or against climate change — unless of course that weather event is a big snowstorm [see "Massive moisture-driven extreme precipitation during warmest winter in the satellite record — and the disinformers say it disproves (!) climate science].
What people should be talking about are record highs versus record lows across the country. The figure above comes from a Weather Channel post by Jonathan Erdman, “July or April? Spring skipped?“:
To the south of this front, temperatures had soared into the 80s and, yes, 90s in many locations, shattering daily record highs. In fact, according to the National Climatic Data Center, in the seven-day period from March 29 through April 4, over 1100 daily record highs were either tied or broken in the nation!
Now that is a heat wave!
The data in the top graphic might remind you of this figure from a must-read 2009 study led by National Center for Atmospheric Research (see “Record high temperatures far outpace record lows across U.S.“):
but I'm happy with this too, it is decently fast, and I can still use my phone as well. This is great for storm chasing
Don't wish hard my friend. PLEASE!
still off earliest heat shutdown date ever in my 10 years of looking after highriser
this morning i refilled the heating system with cold water
tomorrow morning i restart the pumps
tomorrow afternoon i refire the heat
looks like maybe three days may even get some lake effect flurries fri evening early sat morning then warmth returns
back to over 70 by fri next week
Let's you ask how much does the ice melt contributes to such events. With recent volcanic activity in iceland those can even further accelerate melting of glaciers in those areas.
i wounder if this is all relat too the 8.8???
Yikes !!
Earth systems are interconnected, seismic energy from one plate hits neighbouring plates and strong weather events also can effect this. This could trigger earthquakes earlyer as it would happening otherwise.
The Kolbeinsey Ridge rift is under pressure.. witness the activity in Iceland.
just like human systems....if I eat a Twinkie, it shows up on my fat folds....
NCAR begins its release on this study:
Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. The ratio of record highs to lows is likely to increase dramatically in coming decades if emissions of greenhouse gases continue to climb.
“Climate change is making itself felt in terms of day-to-day weather in the United States,” says Gerald Meehl, the lead author and a senior scientist at the National Center for Atmospheric Research (NCAR). “The ways these records are being broken show how our climate is already shifting.”
It’d be nice if the Weather Channel would say something close to that or at least mention the NCAR study if not the overall warming trend. Instead the piece opens with this:
To get a feel for what’s going on in the world’s weather, meteorologists look at weather patterns, namely, the juxtaposition of dips and rises in the jet stream that dictate the weather we feel here on the surface.
Yes, as we know, for many if not most weather reporters, it’s all just one of the greatest coincidences in human history (see “In yet another front-page journalistic lapse, the NY Times once again equates non-scientists — Bastardi, Coleman, and Watts (!) — with climate scientists” and “Is that airlifted snow on your Olympic ski mountain, or is your enormous helicopter just happy to see me?“)
Sadly, for the rest of us, assuming we keep doing what we’re doing, which is to say, nothing, NCAR predicts (and yes, they use the word “predictions” not “projections”):
The modeling results indicate that if nations continue to increase their emissions of greenhouse gases in a “business as usual” scenario, the U.S. ratio of daily record high to record low temperatures would increase to about 20-to-1 by mid-century and 50-to-1 by 2100.
In short, if you like the current heat wave, you ain’t seen nothing yet (see Our hellish future: Definitive NOAA-led report on U.S. climate impacts warns of scorching 9 to 11°F warming over most of inland U.S. by 2090 with Kansas above 90°F some 120 days a year — and that isn’t the worst case, it’s business as usual!”)
full
Ronald says:
April 7, 2010 at 4:20 pm
Northestern Minnesota has the earliest ice-out on the lakes in recorded history; by 7 days.
It’s hard to blame the city heat island effect or the new thermometers compared to the old thermometers for that.
===========================================
MarkB says:
April 7, 2010 at 4:35 pm
The extreme negative Arctic Oscillation that dominated most of the winter, bringing Arctic air far south, is back to neutral conditions.
http://www.cpc.noaa.gov/ products/ precip/ CWlink/ daily_ao_index/ ao_index.html
The Weather Channel needs to update their data. Including one more day brings a net increase of about 350 (370 record highs – 20 record lows).
http://mapcenter.hamweather.com/ records/ 7day/ us.html?c=maxtemp,mintemp,lowmax,highmin
What effect does this have on Joe Bastardi’s patented “population weighted temperature” index?
I’m not sure what part of the country/world global warming deniers can focus on now. Arctic sea ice extent has had a temporary upward blip (which is common in any year), so that’s one spot. The west coast has had below average temperatures.
=======================================
From Peru says:
April 7, 2010 at 4:36 pm
It is not just in the USA that is hot:
http://www.esrl.noaa.gov/ psd/ map/ images/ fnl/ sfctmpmer_01b.fnl.html
(mother site: http://www.esrl.noaa.gov/psd/map/)
The hottest anomalies are, as usual, in the Arctic Basin, where are between +3ºC and +20(!)ºC
There are also strong warm anomalies in Canada (+5 to +10ºC), central Asia (+5 to +10ºC), and Antartica (+10 to +15ºC).
What will the deniers say now?
=======================
PSU Grad says:
April 7, 2010 at 4:46 pm
“What people should be talking about are record highs versus record lows across the country. ”
I disagree. To me, looking only at the record highs and lows focuses undue attention on the weather “drama queens”. Yes, the data are significant. But I like to think that average daily temperatures 5, 6, 7, 8, or more degrees above normal, day after day, week after week, without setting either record highs or lows, can be just as significant. And that’s what some of us have had for the past 5 weeks.
To put it another way, let’s look at caloric intake. Most stuff themselves on Thanksgiving with well over their daily caloric requirement. But it’s only one day and the long term effect isn’t usually very significant, since your body has ways of dealing with these binges.
Alternatively, if you need 2,000 daily calories but take in 2,100 daily calories each day, you’ll gain about 10 pounds in a year. It won’t look like much on a daily basis (after all, 100 calories is “nothing”), but after a year it adds up. So you either need to increase the 2,000 calorie requirement through exercise, or reduce the 2,100 calorie intake by eating less or differently.
Those innocent looking excess 100 daily calories seem more dangerous to me.
[JR: Yes, but the two are connected -- and NCDC tracks one of them.]
#
===============
MapleLeaf says:
April 7, 2010 at 4:53 pm
It is not just the eastern half of the USA and Canada which are experiencing way above average temperatures.
Global MSU satellite temperature data for March (from RSS) were the warmest on record.
http://www.remss.com/ data/ msu/ monthly_time_series/ RSS_Monthly_MSU_AMSU_Channel_TLT_Anomalies_Land_and_Ocean_v03_2.txt
[JR: Near global -- it misses the polls.]
ummmm unrealistic was a good word choice :P
what??? you left out Okeechobee, Tampa and Houston, Brownsville then back around to New York and Boston... sheesh
Stand a better chance of winning the lottery 5 times in a row than seeing that happen
TORNADO WARNING
ILC059-165-080015-
/O.NEW.KPAH.TO.W.0006.100407T2337Z-100408T0015Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE PADUCAH KY
637 PM CDT WED APR 7 2010
THE NATIONAL WEATHER SERVICE IN PADUCAH HAS ISSUED A
* TORNADO WARNING FOR...
WESTERN GALLATIN COUNTY IN SOUTHERN ILLINOIS...
SALINE COUNTY IN SOUTHERN ILLINOIS...
* UNTIL 715 PM CDT.
* AT 634 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 4 MILES
SOUTHWEST OF CARRIERS MILLS...OR 10 MILES SOUTHWEST OF
HARRISBURG....MOVING NORTHEAST AT 45 MPH.
* THE TORNADO WILL BE NEAR...
HARRISBURG BY 645 PM CDT...
ELDORADO BY 655 PM CDT...
EQUALITY BY 700 PM CDT...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
NOW IS THE TIME TO IMPLEMENT YOUR TORNADO PLAN OF ACTION. SEEK
SHELTER INDOORS IN A BASEMENT...OR IN AN INTERIOR ROOM ON THE LOWEST
FLOOR OF A HOME OR BUILDING.
&&
LAT...LON 3792 8840 3768 8823 3760 8871 3773 8870
TIME...MOT...LOC 2337Z 239DEG 40KT 3768 8866
I think they would have a field day covering the storm and then, after having a cumulative 24hours of commercial free coverage in their perspective 'storm modes' they will have to have a commercial marathon to keep from going into debt.
i have to disagree with you taz. my opinion it started in october 2009.
i stand corrected sept 29 was the samoa earthquake
At least it's not "Abrams and Bettes" or whatever their names were immediately afterwards. Those 2 ditz-sounding airhead lookalikes kept me off TWC even when it was broadcasting wx...
Link
hey now be nic what not be rude too them
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