Are tornadoes getting stronger and more frequent?
Are tornadoes and severe thunderstorms getting more numerous and more extreme due to climate change? To help answer this question, let's restrict our attention to the U.S., which has the highest incidence of tornadoes and severe thunderstorms of any place in the world. At a first glance, it appears that tornado frequency has increased in recent decades (Figure 1).
Figure 1. The number of EF-0 (blue line) and EF-1 and stronger tornadoes (maroon diamonds) reported in the U.S. since 1950. There is not a decades-long increasing trend in the numbers of tornadoes stronger than EF-0, implying that climate change, as yet, is not having a noticeable impact on U.S. tornadoes. However, statistics of tornado frequency and intensity are highly uncertain. Major changes in the rating process occurred in the mid-1970s (when all tornadoes occurring prior to about 1975 were retrospectively rated), and again in 2001, when scientists began rating tornadoes lower because of engineering concerns and unintended consequences of National Weather Service policy changes. According to Brooks (2013), "Tornadoes in the early part of the official National Weather Service record (1950-approximately 1975) are rated with higher ratings than the 1975 - 2000 period, which, in turn, had higher ratings than 2001 - 2007." Also, beginning in 2007, NOAA switched from the F-scale to the EF-scale for rating tornado damage, causing additional problems with attempting to assess if tornadoes are changing over time. Image credit: Kunkel, Kenneth E., et al., 2013, "Monitoring and Understanding Trends in Extreme Storms: State of Knowledge," Bull. Amer. Meteor. Soc., 94, 499–514, doi: http://dx.doi.org/10.1175/BAMS-D-11-00262.1
However, this increase may be entirely caused by factors unrelated to climate change:
1) Population growth has resulted in more tornadoes being reported.
2) Advances in weather radar, particularly the deployment of about 100 Doppler radars across the U.S. in the mid-1990s, has resulted in a much higher tornado detection rate.
3) Tornado damage surveys have grown more sophisticated over the years. For example, we now commonly classify multiple tornadoes along a damage path that might have been attributed to just one twister in the past.
Given these uncertainties in the tornado data base, it is unknown how the frequency of tornadoes might be changing over time. The "official word" on climate science, the 2007 United Nations IPCC report, stated it thusly: "There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lighting, and dust storms." Furthermore, we're not likely to be able to develop methods to improve the situation in the near future.The current Doppler radar system can only detect the presence of a parent rotating thunderstorm that often, but not always, produces a tornado. Until a technology is developed that can reliably detect all tornadoes, there is no hope of determining how tornadoes might be changing in response to a changing climate. According to Doswell (2007): I see no near-term solution to the problem of detecting detailed spatial and temporal trends in the occurrence of tornadoes by using the observed data in its current form or in any form likely to evolve in the near future.
Are strong tornadoes increasing?
Stronger tornadoes (greater than EF-0 on the Enhanced Fujita Scale, or F0 on the pre-2007 Fujita Scale) are more likely to get counted, since they tend to cause significant damage along a long track. Thus, the climatology of these tornadoes may offer a clue as to how climate change may be affecting severe weather. Unfortunately, we cannot measure the wind speeds of a tornado directly, except in very rare cases when researchers happen to be present with sophisticated research equipment. Tornadoes are categorized using the Enhanced Fujita (EF) scale, which is based on damage (note that the EF scale to rate tornadoes was adopted in 2007, but the transition to this new scale still allows valid comparisons of tornadoes rated, for example, EF-5 on the new scale and F-5 on the old scale.) So, if a strong tornado happens to sweep through empty fields and never destroy any structures, it will never be rated as a strong tornado. Thus, if the number of strong tornadoes has actually remained constant over the years, we should expect to see some increase in these twisters over the decades, since more buildings have been erected in the paths of tornadoes. However, if we look at the statistics of U.S. tornadoes stronger than EF-0 or F-0 since 1950, there does not appear to be any increase in their number. Not surprisingly, a study accepted for publication in Environmental Hazards (Simmons et al., 2012) found no increase in tornado damages from 1950 - 2011, after normalizing the data for increases in wealth and property (note, though, that I am suspicious of studies that normalize disaster data, since they are prone to error, as revealed by a 2012 study looking at storm surge heights and damages.)
The future of tornadoes
An alternate technique to study how climate change may be affecting tornadoes is look at how the large-scale environmental conditions favorable for tornado formation have changed through time. Moisture, instability, lift, and wind shear are needed for tornadic thunderstorms to form. The exact mix required varies considerably depending upon the situation, and is not well understood. However, Brooks (2003) attempted to develop a climatology of weather conditions conducive for tornado formation by looking at atmospheric instability (as measured by the Convective Available Potential Energy, or CAPE), and the amount of wind shear between the surface and 6 km altitude. High values of CAPE and surface to 6 km wind shear are conducive to formation of tornadic thunderstorms. The regions they analyzed with high CAPE and high shear for the period 1997-1999 did correspond pretty well with regions where significant (F2 and stronger) tornadoes occurred. The authors plan to extend the climatology back in time to see how climate change may have changed the large-scale conditions conducive for tornado formation. Riemann-Campe et al. (2009) found that globally, CAPE increased significantly between 1958 - 2001. However, little change in CAPE was found over the Central and Eastern U.S. during spring and summer during the most recent period they studied, 1979 - 2001. A preliminary report issued by NOAA’s Climate Attribution Rapid Response Team in July 2011 found no trends in CAPE or wind shear over the lower Mississippi Valley over the past 30 years. However, preliminary work by J. Sander of Munich Re insurance company, presented at the December 2011 American Geophysical Union meeting in San Francisco, found that the number of days with very high CAPE values over the eastern two-thirds of the United States between 1970 and 2009 did increase significantly.
Del Genio et al.(2007) used a climate model with doubled CO2 to show that a warming climate would make the atmosphere more unstable (higher CAPE) and thus prone to more severe weather. However, decreases in wind shear offset this effect, resulting in little change in the amount of severe weather in the Central and Eastern U.S. late this century. The speed of updrafts in thunderstorms over land increased by about 1 m/s in their simulation, though, since upward moving air needed to travel 50-70 mb higher to reach the freezing level. As a result, the most severe thunderstorms got stronger. In the Western U.S., the simulation showed that drying led lead to fewer thunderstorms, but the strongest thunderstorms increased in number by 26%, leading to a 6% increase in the total amount of lighting hitting the ground each year. If these results are correct, we might expect more lightning-caused fires in the Western U.S. late this century, due to enhanced drying and more lightning.
Using a high-resolution regional climate model (25 km grid size) zoomed in on the U.S., Trapp et al. (2007) and Trapp et al. (2009) found that the decrease in 0-6 km wind shear in the late 21st century would more than be made up for by an increase in instability (CAPE). Their model predicted an increase in the number of days with high severe storm potential for almost the entire U.S., by the end of the 21st century. These increases were particularly high for many locations in the Eastern and Southern U.S., including Atlanta, New York City, and Dallas (Figure 3). Cities further north and west such as Chicago saw a smaller increase in the number of severe weather days.
Figure 3. Number of days per year with high severe storm potential historically (blue bars) and as predicted by the climate model (A2 scenario) of Trapp et al. 2007 (red bars).
Summary
We currently do not know how tornadoes and severe thunderstorms may be changing due to changes in the climate, nor is there hope that we will be able to do so in the foreseeable future. At this time, it does not appear that there has been an increase in U.S. tornadoes stronger than EF-0 in recent decades. Preliminary research using climate models suggests that we may see an increase in the number of severe storms capable of producing tornadoes over the U.S. late this century. However, this research is just beginning, and much more study is needed to confirm these findings.
References
Brooks, H.E., 2013, "Severe thunderstorms and climate change," Atmospheric Research, Volume 123, 1 April 2013, Pages 129–138, http://dx.doi.org/10.1016/j.atmosres.2012.04.002.
Brooks, H.E., J.W. Lee, and J.P. Craven, 2003, "The spatial distribution of severe thunderstorm and tornado environments from global reanalysis data", Atmospheric Research Volumes 67-68, July-September 2003, Pages 73-94.
Doswell, C.A., 2007, "Small Sample Size and Data Quality Issues Illustrated Using Tornado Occurrence Data", E-Journal of Severe Storms Meteorology Vol 2, No. 5 (2007).
Del Genio, A.D., M-S Yao, and J. Jonas, 2007, Will moist convection be stronger in a warmer climate?, Geophysical Research Letters, 34, L16703, doi: 10.1029/2007GL030525.
Kunkel, Kenneth E., et al., 2013, "Monitoring and Understanding Trends in Extreme Storms: State of Knowledge," Bull. Amer. Meteor. Soc., 94, 499–514, doi: http://dx.doi.org/10.1175/BAMS-D-11-00262.1
Marsh, P.T., H.E. Brooks, and D.J. Karoly, 2007, Assessment of the severe weather environment in North America simulated by a global climate model, Atmospheric Science Letters, 8, 100-106, doi: 10.1002/asl.159.
Riemann-Campe, K., Fraedrich, K., and F. Lunkeit, 2009, Global climatology of Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) in ERA-40 reanalysis, Atmospheric Research Volume 93, Issues 1-3, July 2009, Pages 534-545, 4th European Conference on Severe Storms.
Simmons, K.M., Dutter, D., and Pielke, R., 2012, "Normalized Tornado Damage in the United States: 1950-2011," DOI: 10.1080/17477891.2012.738642
Trapp, R.J., N.S. Diffenbaugh, H.E. Brooks, M.E. Baldwin, E.D. Robinson, and J.S. Pal, 2007, Severe thunderstorm environment frequency during the 21st century caused by anthropogenically enhanced global radiative forcing, PNAS 104 no. 50, 19719-19723, Dec. 11, 2007.
Trapp, R. J., Diffenbaugh, N. S., & Gluhovsky, A., 2009, "Transient response of severe thunderstorm forcing to elevated greenhouse gas concentrations," Geophysical Research Letters, 36(1).
Jeff Masters
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Today, in agreement with Weather456, there is knee/thigh high (lower then yesterday)very clean waves (means no wind chop)The air is 47/gulf temp. is 67 winds presently off shore NE at 9-13 SRQ/WFL/GOMEX
SURFERS: LOOK FOR ANOTHER KICKER FRONT - tuesday. Unfortunately for me - the cold really deters me from getting wet.
Off to work, grateful that the winds have calmed down, horses are so much easier to manage without high winds. Although they will promise to be frisky with this cold snappy weather.....looks like another brain bucket (helmet) day, see you all tonight
That is crap - they obviously never heard of La Nina...
Michael
The climate scientists that are predicting global warming
predicted a stronger El Nino
Not a La Nina
The climate did the opposite of what they were predicting.
If they can't predict that right
How are we supposed to believe that they can predict the future right?
.
GULF OF MEXICO/NORTHWEST ATLANTIC OCEAN WEST OF 50W....
A cold front has moved west of the region allowing surface ridging to take over. A sharp mid-upper level trough moving across the Eastern CONUS is digging well into the Gulf of Mexico. This feature is supporting a 1028 mb surface high over the Florida Panhandle near 31N/88W. This high is producing exceptionally tranquil conditions over the Southern United States from Texas to Florida and most of the Gulf of Mexico. The high is also responsible for weak offshore flow across the Northwest corner of the Gulf increasing towards the Southeastern Gulf where the pressure gradient becomes tightest. 3-6 ft swells everywhere with 6-7 ft seas in the SE Corner.
A cold front extends from the Caribbean across Central Cuba and the Bahamas to beyond 30N/60W. A swath of scattered cloudiness and showers extends within 120 nm either side of the front line.
by W456
That is not "warm water", that is the change in water temperature. anomaly
It's summer down there, it's supposed to change.
"in the long term, ENSO doesn't matter..."
Of course it does.
If not, all of the global warming predictions would have come with a disclaimer:
"for all the denialists, we predict a La Nina in the next two years that will cool global temperatures for the next 30-35 years. But we are still right, after this cooling global temperatures will shoot back up at a alarming rate."
"they obviously never heard of La Nina..."
You said yourself it's obvious.
And they obviously did not predict it, and
missed it.
If they can't predict something that obvious,
how are we supposed to believe they can predict the future?
And don't tell me Al Gore either.
Thanks in advance.
But that is not what that paper you quoted from 1988 said.
It said the La Nina would set global warming back 30 - 35 years.
"We are predicting that by next year, average global temperature will retreat to 1950s levels, slowing up planetary warming by 30 to 35 years."
I'm talking about the current La Nina anyway.
The one that our current climate scientists did not predict.
The same current science and current predictions about the future
that they missed completely.
No one said this was new.
Since the beginning of time, there have been people predicting some sort of disaster or the other.
I don't think the PDO shows that global warming doens't exist...it DOES....but in my blog last year I put up a temp graph like yours Michael and it goes up and down but at a "slant" which goes upward in time....like a sin curve in math but tilted upward from left to right....as I said I'm not gonna re-write my blog here though it's all written there if you want to read it. Otherwise we should probably drop this now.
End of rant
-------------------------------------------
Are you saying that the climate models are predicting that the climate will not be static and it will change?
Wasn't that about the same time that it changed from global warming to climate change?
climate change?
Well, I don't know about that.
The world is in a major food shortage because too many cereal crops are being diverted to bio-fuel - right now.
Rain forests are being cut down at an even faster rate to plant palm trees for palm oil for bio-fuel.
More land in this country is being plowed and planted with corn for bio-fuel - pesticides, fertilizer, water -
15 million new acres of farm land were converted to corn in 2007, additional to previous years.
My biggest fear is that we are running helter skelter trying to fix something, that may or may not even need fixing.
and doing more damage in the process.
Are rain drops getting wetter?
and doing more damage in the process."
This is a good point. I believe global warming exists, and does need fixing, but we have to be careful about how we fix it.
For example, we've suddenly discovered that growing corn for ethanol actually puts out a lot of CO2 right now, and we won't break even for over a century. Additionally, the fertilizer that gets into the water is expected to cause a much larger dead zone in the gulf now, possibly causing the collapse of the entire ecosystem there.
It's true that we may be approaching the point of no return, but we might be past it already, or it might be far off. We don't know. We have to make sure we don't do too much damage with knee-jerk responses. We need to mount a carefully planned, tested response to global warming, and we need to follow up to see if it works and what the other consequences are.
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Burning alcohols derived from vegetables should take us out at a faster pace than burning fossil fuels.
Shhh! Don't tell anyone, this is a great big secret that most of the GW religious leaders will not talk about.
There is actually less available energy in a unit volume in ethanol vs gasoline. The result? More ethanol must be burned to do the same amount of work leading to more CO2, NOx, and hydrocarbon emission.
Hey, guys, us coolies and/or doubters cannot have it both ways. We are very quick to shoot down the warmies over any singular weather event/day/month/year as some sort of proof of GW. The same is true of the reciprocal. No single event/day/month/year/or ENSO cycle means anything in the grand scheme of multi-decadal climate change in either direction. Notice I did not cover any thought of status quo climate...if you believe that enjoy your bliss.
As to models, they are very sensitive to the slightest erroneous assumption/incorrect data/current conditions. Did I say climate models? No. Any complex physical model. I just finished (yesterday) a full rehash of Katrina in a storm surge model with a change in the tidal cycle. If the high/low tides occurred 3 hours earlier, the surge along the MS coast is very different during/after Katrina. More surge in a few areas (west, towards Slidell), but overall more than a meter less surge for most of the coast.
That is an example of the sensitivity to a single changed parameter. What if there is an analagous behavior in the climate models? Predicted drought turns into normal rainfall? Sea level rise drastically reduced? Increased shear (fewer TCs)? I am not claiming to know, but I do know that my faith in a nearly infantile field of climate modeling is not strong. We have difficulty modeling frontal passages more than a week in advance. Long-term modeling is built around not resolving such details, but just assuming they happened and assuming the results. I my view, that needs a lot of work before it can intelligently be used to plan for any future predictions.
History teaches that a lack of hurricane awareness and preparation are common threads among all major hurricane disasters. By knowing your vulnerability and what actions you should take, you can reduce the effects of a hurricane disaster. Hurricane Preparedness Week during 2008 will be held May 25th through May 31st.
Link
Do you Have a Family Disaster Plan?
Hurricane Awareness:
Family Disaster Plan
1.Discuss the type of hazards that could affect your family. Know your home's vulnerability to storm surge, flooding and wind.
2.Locate a safe room or the safest areas in your home for each hurricane hazard. In certain circumstances the safest areas may not be your home but within your community.
3.Determine escape routes from your home and places to meet. These should be measured in tens of miles rather than hundreds of miles.
4.Have an out-of-state friend as a family contact, so all your family members have a single point of contact.
5.Make a plan now for what to do with your pets if you need to evacuate.
6.Post emergency telephone numbers by your phones and make sure your children know how and when to call 911.
7.Check your insurance coverage - flood damage is not usually covered by homeowners insurance.
8.Stock non-perishable emergency supplies and a Disaster Supply Kit.Link
9.Use a NOAA weather radio. Remember to replace its battery every 6 months, as you do with your smoke detectors.
10.Take First Aid, CPR and disaster preparedness classes.
Thanks
Will
Global Warming? 28 degrees in Ocala, Florida last night! Cruel weather, recent rains & moderate temps had everything blooming-until last night.
Not Global Warming, think more Climate Change...it's a very touchy subject, and only time will tell who has the right spin on it, but being an extremist in either camp does everyone a disservice
************
I'm beginning to believe that research might show that any upward trends in recorded temperatures might be demonstrated to correlate with the membership trends on WU. It seems that whenever someone rubs the GW/CC chestnut this site starts emitting more heat than light. Now I am keeping in mind that my first research methods drummed it into our heads that "correlation is not causation" but it may "Call For Further Research.
Some good posts recently, and some bad ones too. The GW 's and the Status Quo keepers.
Its all good in the end.
By the way, realy nice weather here at 11n 61w, with dry season setting in. Cool, breezy days with occasional showers and all the trees flowering, and losing leaves.
Cutting fire traces and topping up watertanks in preparation for April and May, when the fires rage.
OK-climate change. But with a worldwide population explosion continuing, there would seem to be little hope of bringing emissions under control. Everybody wants a nice, comfortable life, and that costs.
Research, gs...we've knwon about these issues for a very long time. We should have been researching alternatives this whole time...oh, well *SIGH*
The current anomaly relative to the 1985-1993 (omitting 1991 & 1992) climatology shows a warm GoM, a cool Caribbean and a cold Pacific except for some of Central America. I personally think the anomaly-relative-to-some-other-measurement does not get enough play here and elsewhere. "Anomalous relative to what?" should cruise through your minds every time the anomalous word comes up. I am certain I could build a dataset that show a cool anomaly in the GoM right now.
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