Were the Recent Tornadoes the Result of Global Warming?

From the Cliff Mass Weather Blog

Tornado damage, Courtesy of State Farm Insurance

Powerful, long-lived tornadoes struck western Kentucky, southern Illinois, and the vicinity on Friday night.  And within hours, major media outlets, national politicians, and several climate activists were claiming that global warming was partly or mainly to blame.  


The head of FEMA talked about the recent tornadoes as being part of a “new normal” forced by climate change.

As I will demonstrate below, these claims are contradictory to the best science and at odds with respected international and national scientific assessments.  Many are based on simplistic arguments that demonstrate a lack of understanding of the ingredients required for severe convection (thunderstorms) or evince a lack of knowledge of the historical record.

Have Strong Tornadoes Been Increasing in the U.S.?

The very first question one must ask when evaluating the role of global warming (or “climate change” as some folks prefer), is whether there is a trend.   If global warming is contributing to severe tornado frequency or strength, one would expect an extended trend over decades.

Below you will see a plot of the frequency of strong tornadoes (EF 3, 4, 5) over time for the U.S. (and keep in mind that such strong tornadoes are pretty much limited to the Plains states and the SE U.S.) from the NOAA/NWS Storm Prediction Center.   The trend is DOWNWARD towards fewer strong tornadoes.  So if there is a trend to a “new normal” it is for LESS strong tornadoes.


Normalized tornado damage (which considers changes in changes in the cost of living and growth) is similar.  No upward trend, downward if anything.


Some individuals are displaying the trend of all tornadoes over time, but this is problematic because we are now much more capable of observing the weakest tornadoes, many of which were missed 40 to 80 years ago.
The tornado trend data provides strong evidence that the claims of an increasing number of strong tornadoes are unfounded.  And even if they were increasing, one would have to prove that global warming was to blame.  
There have been suggestions, based on one paper, that there is a trend towards changing the distribution of U.S. tornadoes (more east of the Mississippi), perhaps due to global warming,   
However, this paper does not actually look at changes in tornado frequency, but rather trends in an indirect index called STP.  They do not consider changes in the frequency of strong storms and use the problematic total number of tornadoes as a verification parameter.  I could go into the technical details more, but this reference is very weak support for any claims global warming is causing more severe tornadoes around Kentucky.
What do international and national evaluations by the scientific community suggest about the connection between global warming and U.S. tornadoes?
They are quite clear:  there is little evidence connecting global warming with severe tornado frequency over the U.S.


The latest IPCC (Intergovernmental Panel on Climate Change) report states:

  • “trends in tornadoes… associated w/ severe convective storms are not robustly detected”
  • “attribution of certain classes of extreme weather (eg, tornadoes) is beyond current modeling and theoretical capabilities”
  • “how tornadoes… will change is an open question”

The Fourth U.S. National Climate Assessment notes:
“Observed trends and projections of future changes in severe thunderstorms, tornadoes, hail, and strong wind events are uncertain.”

Claims Unsupported By Science or Data
One of the great frustrations to scientists like myself is when laypeople make claims unsupported by rigorous scientific reasoning or facts.  The claims regarding tornadoes and climate are prime examples.

Courtesy of Peter Hess

One popular claim is that climate change makes weather more extreme and thus one can expect tornadoes to be more extreme.  Climate change does NOT make all extreme weather more extreme.  And it has varied effects on the key ingredients of severe thunderstorms over the U.S.
Others suggest that warming temperatures produce more strong thunderstorms and thus more tornadoes.
I am afraid the physical world is not so simple.  These individuals and media outlets are making claims without support in theory or observations.  
Tornadic Storms Require a Complex Array of Conditions
Strong tornadic thunderstorms are rare for a reason:  it takes a very complex array of simultaneous conditions to produce them:   

  • Strong atmospheric instability is essential, with temperature declining rapidly with height.
  • A large change in wind with height (wind shear) is critical, both for allowing storms to become intense and to produce the rotation in supercell thunderstorms, the parents of most severe tornadic events.
  • And one needs upward motion or lift to release the instability, and this can be from a strong front or an upper-level trough or jet streak.

And there are more requirements I won’t go into here. 

Simply warming the surface is not enough to enhance severe thunderstorm development. 

 Good evidence for this is provided by a map showing the climatology of tornadoes around the planet.  Tornadoes are infrequent in the warm, humid tropics, where large and frequent thunderstorms are noted.  Essential ingredients are missing.

So claims that warming will produce more severe tornadic thunderstorms should be taken with a big grain of salt…severe tornadic thunderstorms depend on an array of requirements, some of which could well weaken under global warming

Finally, let me note that even the local warming claims have issues.   For example, we are in a moderate La Nina year, which produces warmer than normal conditions over the southeast U.S.  Blaming all of it on global warming is problematic.

The Bottom Line

Claims that the severe tornadoes experienced last Friday evening were the result of global warming/climate change have little basis in the scientific literature or meteorological observations.  Observed trends contradict the claims. No such conclusions have been made by the leading scientific groups (e.g., the IPCC).

Unfortunately, it is a potent example of the politicization of weather and climate, which leads to fearful populations and a lack of action on key protective technologies, such as improved construction and better warnings.

The evolution of the supercell thunderstorm that produced the Mayfield tornado as shown by NWS weather radars

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Scissor
December 16, 2021 6:17 pm

Wait until the insurance industry catches on and lobbies for indemnity.

Bryan A
Reply to  Scissor
December 16, 2021 9:21 pm

Well certainly the December Storms are brought to you by “Global Warming”
Also the Clear Sky Shining Sun in Cali is brought to you by “Global Warming”
The last Rain Drop to wet my face today was brought by “Global Warming”
The current Cold Clear Night Air is brought to you by “Global Warming”
The last 5′ of frozen water in the Sierra Nevada Mountains…”Global Warming”
The butterfly Flatus that mussed my hair today…”Global Warming”

Last edited 1 month ago by Bryan A
Alan the Brit
Reply to  Bryan A
December 17, 2021 12:39 am

You must not forget that it is NOT global warming, but Climate Change, that way it doesn’t matter which way the temperature goes, but if “they” keep calling it global warming & the temperature starts to fall, they have a big, big problem with credibility, which as far as I am concerned collapsed years ago!!! I am afraid the poorer nations will have to wait for their free hand-outs of Western nations cash!!! I know, why don’t these poorer nations develop a political system called “democracy”, start to develop on a Western democratic style, up to & including looking after the environment as Western nations do, it’s just a thought that’s all!!!

Observer
Reply to  Alan the Brit
December 19, 2021 4:54 am

You think moar “democracy” will solve developing nations’ problems? How’s all that untrammelled democracy working out for the developed world?

Democracy is just mob rule.

The US became great because it was a constitutional republic, with institutions restricting government over-reach. At least hitherto.

It also became great because there was a lot of “unowned” (or poorly protected – take your pick) land that enabled the majority of the populace to become property owners. And it became great because cheap energy, technology, and the Old World destroying themselves not once, but twice during the 20th century with pointless wars.

Last edited 1 month ago by Observer
oeman 50
Reply to  Bryan A
December 17, 2021 6:32 am

All bad weather only has to be a few hours gone when it is declared to be “consistent” with climate change. Rules of logic indicate if everything is caused by climate change, then it reveals nothing and is a fallacy. But then who said this is about logic?.

Tom Halla
December 16, 2021 6:18 pm

There should be an artifact of having better and better coverage by Doppler radars, which pick up minor tornados that do no damage.
Plus, when the last outbreak of tornadoes happened, there was quite a contrast in temperature between the central Plains and the Southeast, which is a situation leading to thunderstorms and tornadoes. It was the divergence in temperature, not warmth as such.

Tom Abbott
Reply to  Tom Halla
December 16, 2021 9:01 pm

Moisture was the key to the tornadoes, not warm air, or a contrast between the warm and cold air.

The warm air and the contrast between the warm and cold air was just the same for Oklahoma as it was for all the States to the east of Oklahoma.

No tornadoes broke out in Oklahoma that night. The reason is the air over Oklahoma was dry. The humidity started in Arkansas and ranged to the east, and when the storm front hit Arkansas, the tornadoes started blowing up.

Tim Gorman
Reply to  Tom Abbott
December 17, 2021 2:15 pm

I suspect it was even more complicated than we can know. Here in east central Kansas we had 80% humidity with 70F just before the storm hit about 5:30pm. When the front moved through the temp dropped 40F to 30F and we saw 65mph straight line winds (other location in KS saw 100mph). Humidity dropped from 80% to 40% as the front moved through but rose back up to 70% after it moved through. The barometer fell from 29.8 to 29.4 during the day but after the storm front rose to 30.2 overnight.

We just didn’t see the rotation necessary for tornadoes to develop like locations east of us.

Jtom
December 16, 2021 6:43 pm

April 1–6[edit]
A tornado outbreak sequence of 32 tornadoes hit areas from California to Virginia.[20] It started with four tornadoes on April 1, including three rare early to late-morning F1 tornadoes that touched down in California.[21] The first one caused considerable damage to the San Francisco International Airport.[22] “ (Wikipedia) The year was 1958

“The first six days of December 1953 produced a destructive and deadly tornado outbreak sequence[nb 1] across the Southern United States. There were 19 confirmed tornadoes, including a violent F4 tornado that hit the northwest side of Alexandria, Louisiana and even more violent F5 tornado that hit Vicksburg, Mississippi. In all, the tornadoes killed 49 people, injured 404 others, and caused $45.709 million (1953 USD) in damage. This was the last in a series of deadly and catastrophic outbreaks to strike the US in 1953.” Wikipedia.

The climates didn’t change in 1953 or 1958. Weather happens.

Last edited 1 month ago by Jtom
Bryan A
Reply to  Jtom
December 16, 2021 9:24 pm

The climate is obviously changing … to what it was back in the early – mid 1950s

Jeff corbin
Reply to  Jtom
December 17, 2021 7:45 am

Feb 1998 a water spout came off the gulf of Mexico during a fierce storm that was part of system that ended up a Nor’Easter. The water spout continued on land as a tornado and hopped over Port Charlotte and killed 42 people in a park camp 12 miles inland. If it has dropped down on the marshlands and moved of the eastern shore of Florida, it would never made the news. Winter storms happen.

Last edited 1 month ago by Jeff corbin
RMoore
December 16, 2021 6:54 pm

NPR reports yesterday’s weather as ‘Wild Winter Storm’ noting high wind gusts set record.
Today is Dec 16th.

Shoki Kaneda
December 16, 2021 8:45 pm

Everything bad that occurs is your fault for contributing to global warming. Everything good that occurs is due to Climatistas caring.

Philip
December 16, 2021 9:05 pm

Why would it have to be a question of global warming? Has this area ever before experienced a tornado? If so (or not), in the absence of any warming, global warming becomes disinformation.

Tom Abbott
December 16, 2021 9:07 pm

From the article: “There have been suggestions, based on one paper, that there is a trend towards changing the distribution of U.S. tornadoes (more east of the Mississippi), perhaps due to global warming, ”

I saw that paper. My experience is there is no trend for the tornado track to move eastward from the usual track in the central U.S.

It all depends on how the jet streams configure themselves. Sometimes the tornado track is in the center of the nation, and sometimes it does move east of there, but it always moves back and does not stay in the east, so moving eastward is just temporary depending on how the wind is blowing.

I’ve been watching those storm tracks for a long time.

Joao Martins
Reply to  Tom Abbott
December 17, 2021 5:39 am

What is your criticism? The article does not lie: it merely states suggestions that there is a trend perhaps due to… (/s needed?)

Jeff Alberts
December 16, 2021 9:13 pm

Many are based on simplistic arguments that demonstrate a lack of understanding of the ingredients required for severe convection (thunderstorms) or evince a lack of knowledge of the historical record.”

Oooh! Cliff just called Mann a climate simpleton! Nice!

Luke
December 16, 2021 10:25 pm

This 25 mile F3 tornado and a bunch of others including a few F4s happened in Wisconsin and Iowa and Illinois and Missouri in January of 1967. IF it hadn’t happened way back then, but happened next year the amount of bedwetting would be historically unprecedented. How many PPMs ago was the winter of 1966-67, anybody? https://en.m.wikipedia.org/wiki/1967_St._Louis_tornado_outbreak

Luke
Reply to  Luke
December 16, 2021 10:26 pm

By the way, the Great Chicago blizzard followed two days later.

Welsh Dragon
December 16, 2021 10:35 pm

This paper was refreshing to read, a bit of a rarity.

https://www.nature.com/articles/s41598-021-81143-5

Bill Rocks
Reply to  Welsh Dragon
December 17, 2021 8:02 am

Yes. Very welcome scientific paper.

Some persons or organizations who claim that CAGW is causing these storms are performing malpractice.

Doonman
December 16, 2021 10:39 pm

Claims that the severe tornadoes experienced last Friday evening were the result of global warming/climate change have little basis in the scientific literature or meteorological observations.

That does not seem to bother the President Of The United States one iota. He was the first to proclaim nationwide that it does. He is on record as saying so and cannot deny that he did.

People who support the current administration and their policies must also ask what other misinformation they distribute and why the MSM and all social media distribute whatever the POTUS says without fact checking first.

Derg
Reply to  Doonman
December 16, 2021 11:56 pm

Let’s go Brandon indeed

Alan the Brit
Reply to  Doonman
December 17, 2021 12:48 am

Perhaps like Facebook, the fact checking is merely a selective process based on what they want to publish & fact check accordingly, possibly even altering said facts in readiness for “fact checking” before publication!!!

Joao Martins
Reply to  Doonman
December 17, 2021 5:51 am

Thomas Jefferson would be appalled if he would imagine such a level of arrogant ignorance inhabiting the White House. And seeing it happen would perhaps be devastating for his trust in democracy.

Mike Maguire
December 17, 2021 12:28 am

Great article/discussion as usual by Cliff.

He mentioned a powerful jet stream(jet streak) as a key element in events like this. It certainly was this week and last week.

That usually occurs when an unusual cold air mass is located just north or northwest of unusual warmth. Exactly the scenario during these 2 severe storm/tornado outbreaks.
In this case, the cold was widespread across Canada. Without it, the jet stream would have been MUCH weaker and not have caused the amount of lift or rotation or wind sheer dynamics.

We don’t have tornado outbreaks in the tropics because cold air masses don’t make it that far south…… so upper level jet streams are relatively tame in the warm/humid lower latitudes.

https://www.eldoradoweather.com/canada/current-conditions/temperatures.html

Screenshot 2021-12-16 at 13-32-33 Canadian Temperature Current Conditions, covering Temperature Readings for all of Canada.png
Mike Maguire
Reply to  Mike Maguire
December 17, 2021 1:05 am

Global warming has warmed the coldest places of the northern hemisphere the most…..the ahighest latitudes. This has decreased the meridional temperature gradient resulting in q.weakened jet streams and cold fronts.

We know that this should happen based on atmospheric physics and meteorology 101.

This has also been confirmed by observations/empirical data collected over the last 6 decades that shows a big drop in violent tornadoes that coincides with global warming.

Derg
Reply to  Mike Maguire
December 17, 2021 1:48 am

No kidding, global warming makes more tornadoes or less tornadoes depending on how they are measuring 😉

Ed Zuiderwijk
December 17, 2021 1:17 am

Distinguished climate huckster Mann was shamelessly declaring how right he had been all along. And of course his proclamations were lapped up by the MSM as if it were manna from heaven. Nothing new there.

Prjindigo
December 17, 2021 2:00 am

Hurricanes, Cyclones and Tornadoes are driven by the atmosphere being cooler than the surface air. Increasing the atmospheric temperature will reduce them. Decreasing surface temperature can reduce them.

So this obviously hasn’t happened.

2hotel9
December 17, 2021 4:09 am

Were recent tornadoes the result of global warming? No. Next stupid question.

ipsler
December 17, 2021 5:06 am

“pseudo–global warming methodology” article suggesting stronger tornadoes is featured in EOS this week.

A Hotter Earth Means Stronger TornadoesAlthough their frequency may decrease, models suggest anthropogenic climate change will increase the intensity of tornado outbreaks.

Joao Martins
December 17, 2021 5:35 am

Were the Recent Tornadoes the Result of Global Warming?

NO!, Not at all! Recent Tornados are the result of Anthropogenic Global Warming!

M.W.Plia
December 17, 2021 5:43 am

60 minutes is devoting their program to the subject this Sunday. They are calling the presentation “The New Science of Superstorms”

Maybe (cough,cough) we’ll get some answers.

Ireneusz Palmowski
December 17, 2021 7:53 am

Currently, heavy thunderstorms continue to attack the plains.comment image
https://map.blitzortung.org/#6.16/35.864/-92.9
The further south the Arctic jet stream descends on the west coast, the stronger convection will be on the central plains. The strength of the winter front is tremendous.comment image

Last edited 1 month ago by Ireneusz Palmowski
AGW is Not Science
Reply to  Ireneusz Palmowski
December 17, 2021 9:35 am

In other words, weather. NOT “climate change.”

Ireneusz Palmowski
December 17, 2021 7:57 am

It is interesting to see what causes the ozone blockage in the lower stratosphere. It is changes in ozone during times of low solar activity that cause anomalies in the winter circulation.
http://tropic.ssec.wisc.edu/real-time/mtpw2/product.php?color_type=tpw_nrl_colors&prod=alaska&timespan=24hrs&anim=html5

AGW is Not Science
Reply to  Ireneusz Palmowski
December 17, 2021 9:37 am

You’ll certainly be excommunicated from the climate cult should they discover you have made even a suggestion that the Sun impacts any of the “bad” stuff they like to blame on “climate change.”

eyesonu
December 17, 2021 8:10 am

Great (leading) photo of a tornado. Right click and open in a new tab then zoom to 150% – 170%. Ponder what is happening long and hard. Note the ‘pyramid’ shape at ground level and the condensation around it. Ponder the cloud base surrounding the vortex. Keep in mind that low level air flow is moving toward the vortex and the vortex is creating a strong updraft. Some forces at play … phase change due to pressure drop from velocity, temp, and elevation (can visualized), kinetic energy, etc. Consider a horizontal cross section of the vortex wind speed at various elevations of say 150′ intervals. Consider the pressure impacts inside the vortex and possible core direction of air flow at change in elevation (close to ground level at the pyramid vs a bit higher).

A lot to think deeply about. The wonders of nature have no bounds!

eyesonu
Reply to  eyesonu
December 17, 2021 12:57 pm

Damn, I will resume deer hunting again tomorrow and no discussion on my post above. Anyway, note the apparent ‘hole’ in the base of the cloud on the leading edge of the vortex (left). Extreme air flow from below condensing at a higher elevation to continue cloud development and thus overall direction of the tornado and cloud? Mass air flow being drawn in to the sides of the already developed cloud as well as from below? Just open your eyes and see what you see. That photo is worth a thousand words!

I gotta get back to processing deer and got room for one more.

AGW is Not Science
December 17, 2021 9:20 am

No such conclusions have been made by the leading scientific groups (e.g., the IPCC).

Agree with everything else you said, Cliff but this statement is laughable. The IPCC is not a “leading scientific group,” it is a perpetrator of propaganda about climate. The underlying scientific reports, which you correctly cite, are seen and heard by nobody, they are just ignored and even contradicted by the IPCC faithful as they cook up the latest fear-mongering “Summary for Policymakers.”

Furthermore, they cynically exclude good science that contradicts their view of human-caused “climate catastrophe” (which does not exist) and include pieces of trash penned by non-scientist “activists” when it suits them, despite supposed “standards” to the contrary. The fact that even they cannot hide the facts you refer to speaks volumes about what utter nonsense any claim that “bad weather” generally, and tornadoes in particular, has anything to do with “climate change” (aka warming of the climate) really is.

Sara
December 17, 2021 4:28 pm

The head of FEMA talked about the recent tornadoes as being part of a “new normal” forced by climate change. – article

Hogwash. Idiot’s reaction to what is nothing but normal spring storm systems. Perhaps this FEMA person should look up the 1974 tornado swarm that started down south of my state, moved north and pulled more and more twisters into it, until it flattened every town and building in its path and finally destroyed Xenia, OH. That had nothing to do with globull BS warming. Had everything to do with wind shear and perfect conditions for a swam storm,.

That was NOT the only storm swam like that. There have been others – many others – but that is the one I remember the most because it cut through the county my parents were living in at that time.

Alonzo
December 18, 2021 10:55 am

Were the Recent Tornadoes the Result of Global Warming?

I don’t know, is late night talk shows having no grace, generosity or humour in bringing people together the result of Global Warming.?

Is the cavity recently found in my mouth due to Global Warming?

These are not ridiculous questions because the amount of evidence is exactly the same in all three cases.

December 19, 2021 11:20 am

Tornadoes aren’t getting worse, but their season is having some shifting away from early summer. This means a few more tornadoes at times of the year when their daily pattern is less concentrated to afternoon and early evening, which makes ones at other timers of the day a little more likely.

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