Extreme weather events linked to climate change impact on the jet stream

March 27, 2017, Pennsylvania State University
On the is an image of the global circulation pattern on a normal day. On the right is the image of the global circulation pattern when extreme weather occurs. The pattern on the right shows extreme patterns of wind speeds going north and south, while the normal pattern on the left shows moderate speed winds in both the north and south directions. Credit: Michael Mann, Penn State

Unprecedented summer warmth and flooding, forest fires, drought and torrential rain—extreme weather events are occurring more and more often, but now an international team of climate scientists has found a connection between many extreme weather events and the impact climate change is having on the jet stream.

"We came as close as one can to demonstrating a direct link between change and a large family of extreme recent ," said Michael Mann, distinguished professor of atmospheric science and director, Earth System Science Center, Penn State. "Short of actually identifying the events in the climate models."

The unusual events that piqued the researchers' interest are things such as the 2003 European , the 2010 Pakistan flood and Russian heatwave, the 2011 Texas and Oklahoma heat wave and drought and the 2015 California wildfires.

The researchers looked at a combination of roughly 50 climate models from around the world that are part of the Coupled Model Intercomparison Project Phase 5 (CMIP5), which is part of the World Climate Research Programme. These models are run using specific scenarios and producing simulated data that can be evaluated across the different models. However, while the models are useful for examining large-scale climate patterns and how they are likely to evolve over time, they cannot be relied on for an accurate depiction of extreme weather events. That is where actual observations prove critical.

The researchers looked at the historical atmospheric observations to document the conditions under which extreme weather patterns form and persist. These conditions occur when the jet stream, a global atmospheric wave of air that encompasses the Earth, becomes stationary and the peaks and troughs remain locked in place.

"Most stationary jet stream disturbances, however, will dissipate over time," said Mann. "Under certain circumstances the wave disturbance is effectively constrained by an atmospheric wave guide, something similar to the way a coaxial cable guides a television signal. Disturbances then cannot easily dissipate, and very large amplitude swings in the jet stream north and south can remain in place as it rounds the globe."

This constrained configuration of the jet stream is like a rollercoaster with high peaks and valleys, but only forms when there are six, seven or eight pairs of peaks and valleys surrounding the globe. The jet stream can then behave as if there is a waveguide—uncrossable barriers in the north and south—and a wave with large peaks and valleys can occur.

"If the same weather persists for weeks on end in one region, then sunny days can turn into a serious heat wave and drought, and lasting rains can lead to flooding," said Stefan Rahmstorf, Potsdam Institute for Climate Impact Research (PIK), Germany.

The structure of the jet stream relates to its latitude and the temperature gradient from north to south.

Temperatures typically have the steepest gradients in mid-latitudes and a strong circumpolar jet stream arises. However, when these temperature gradients decrease in just the right way, a weakened "double peak" jet stream arises with the strongest jet stream winds located to the north and south of the mid-latitudes.

"The warming of the Arctic, the polar amplification of warming, plays a key role here," said Mann. "The surface and lower atmosphere are warming more in the Arctic than anywhere else on the globe. That pattern projects onto the very temperature gradient profile that we identify as supporting atmospheric waveguide conditions."

Theoretically, standing jet stream waves with large amplitude north/south undulations should cause unusual weather events.

"We don't trust yet to predict specific episodes of extreme weather because the models are too coarse," said study co-author Dim Coumou of PIK. "However, the models do faithfully reproduce large scale patterns of temperature change," added co-author Kai Kornhuber of PIK.

The researchers looked at real-world observations and confirmed that this temperature pattern does correspond with the double-peaked jet stream and waveguide patter associated with persistent extreme weather events in the late spring and summer such as droughts, floods and heat waves. They found the pattern has become more prominent in both observations and climate model simulations.

"Using the simulations, we demonstrate that rising greenhouse gases are responsible for the increase," said Mann. The researchers noted in today's (Mar. 27) issue of Scientific Reports that "Both the models and observations suggest this signal has only recently emerged from the background noise of natural variability."

"We are now able to connect the dots when it comes to human-caused global warming and an array of extreme recent weather events," said Mann.

While the models do not reliably track individual , they do reproduce the jet stream patterns and temperature scenarios that in the real world lead to torrential rain for days, weeks of broiling sun and absence of precipitation.

"Currently we have only looked at historical simulations," said Mann. "What's up next is to examine the projections of the future and see what they imply about what might be in store as far as further increases in extreme weather are concerned."

Explore further: Weather extremes: Humans likely influence giant airstreams

Related Stories

Weather extremes: Humans likely influence giant airstreams

March 27, 2017

The increase of devastating weather extremes in summer is likely linked to human-made climate change, mounting evidence shows. Giant airstreams are circling the Earth, waving up and down between the Arctic and the tropics. ...

Recommended for you


Adjust slider to filter visible comments by rank

Display comments: newest first

1.3 / 5 (13) Mar 27, 2017
The rules insist that you are not allowed to use weather to either support or deny global warming. I tried that once and was shot down immediately. You can not have it both ways...
4 / 5 (12) Mar 27, 2017
"SamB" and "Earthling Too", you are anti-science trolls, who actually believe you might know something about science, and perhaps even the subject matter..... and fail miserably. Your ignorance is such that you are completely transparent. It's patently obvious to even the most casual observer.
3.1 / 5 (15) Mar 27, 2017
" In the 1970s scientists were warning about global cooling, "

Nope. That came from the musings of one scientist wondering "What if, . . . ".

It got picked up and reported and reported.
3.5 / 5 (2) Mar 27, 2017
If you can't refute the argument, refute the person..... or, any deviation from the 'narrative' will be punished with verbal attacks for now and if we can get our way show trials for crimes against humanity/Gia.
4.1 / 5 (13) Mar 27, 2017

I repeat, the term "climate" has not been adequately defined. Man's activities with regard to industry and fossil-fuel burning cannot influence global weather in a span of only a few hundred odd years. That is a blip in the history of a planet that is thought to be 4.5 billion years.

Man's activities with regard to industry and fossil-fuel burning NOT only can but it DOES influence global weather in Every Respect. The Unnatural waste Pumped into the atmosphere by an Unnatural Colossal amount Makes it happen Right now as i type and have been doing so for Decades ! !

You Clearly is simply just another antigoracle sock who understands Nothing about science, don't care about earth's health and can give absolutely NO evidence Refuting the devastation caused By Human Induced Climate Change !

As always YOU are incapable of comprehending the Unlimited Amount of Human Induced Climate change by Polluting Fossil Fuels !
3.3 / 5 (14) Mar 27, 2017
Is your entire life a dichotomy? Are there no areas of grey?

How about color? Patterns?


We are showing and building the ways to do it now. All we need is for those who base their positions on politics or emotion to use facts and reason.
4.3 / 5 (11) Mar 27, 2017
Of course you would laugh at it, all you care about is your own Greed and pumping fossil fuels into the air till the whole world is covered in thick Smog like Beijing, just like the rest of the Global Goon Oil Empire, Your very nature exposes your values to the world everyday.

The solutions have been endlessly discussed, yet for some strange reason, you don't want the earth to heal, nor do you care, gladly everyone sees that.
Captain Stumpy
4.6 / 5 (11) Mar 27, 2017
As I've said before, when science tries to use moral arguments or appeals to emotion it becomes unscientific
scientists aren't making moral arguments or appeals to emotions: politicians are
and you are as well - above
I repeat, the term "climate" has not been adequately defined
wrong: according to the World Meteorological Organization (WMO), NOAA, EPA, and everyone else, "climate" has a specific definition with two categories - narrow or wider is listed here (and both are related to each other): http://www.cwcb.s...ions.pdf

Questioning the so-called "settled science" is exactly what real scientists should be doing
that is the foundation of science and is important to note it is the validation process

also note: just because you don't like the results doesn't mean they're not true as you intimate with your above diatribe
4.3 / 5 (11) Mar 27, 2017

@HeloMenelo: Get a grip. No one pumps fossil fuels into the air. That would be a waste. We pump them into fuel tanks that feed engines which perform work. If you prefer to ride the bicycle instead, good for you. Just remember that you are exhaling even more terrible CO2 as you sweat your way forward.

No sh$t numb nuts, get a brain, it doesn't matter 2 sh$ts where you pump your filthy fuel into, the end result is the pollutant it creates, what a dumb statement.

As I've said before, when science tries to use moral arguments or appeals to emotion it becomes unscientific. All such attempts do it no favors and all who would use such tactics are immediately suspect.

What a cracker, You do NOT understand science, Nor care about science Whatsoever. The Scientific Proof has been presented for Decades,yet all you come up with is some dumb emotion statement. O it feels good to know the world sees this ;)
Captain Stumpy
4.6 / 5 (11) Mar 27, 2017
@earth cont'd
Simply put, we don't know. Much of the data is skewed, much of it is massaged and adjusted as needed to fit an agenda.
total delusional bullsh*t
if you were talking one country you might have an argument... but you're talking cultures that can't agree that bacon is tasty let alone on some grand global conspiracy

if you could prove using the same scientific method that scientists use that the "data is skewed" you would be the hero of the deniers movement - and rich to boot

more importantly: making a claim doesn't make it true
there are studies proving the well financed anti-science movement against AGW ( http://www.drexel...nge.ashx ) - but you have yet to provide any empirical evidence supporting your own claims

3.4 / 5 (10) Mar 27, 2017
"@ gkam: Who is "We?" You said you're not a scientist, so what exactly what are your solutions, . ."

You do not have to be a scientist to design a better way to do something. I worked in industries which had to evolve to survive. Some of my solutions are to use anaerobic digestion for all animal wastes, use the gas to produce electricity and hot water for the operations and export the rest to neighbors through the grid.

It is to replace standard appliances and energy-users with more efficient devices/systems.

I also suggest you get solar PV if it is practical where you live, as we have done, and use it for house and EV.

Insulate and weather-tighten the building envelope where you live. Consider putting off using some appliances when the peak arrives to keep from using the most polluting power.

Lots o' stuff to get done.
Captain Stumpy
5 / 5 (9) Mar 27, 2017
Better still, take Captain
@earthling delusional troll
so- you can't make an argument from evidence or science, therefore you choose to use "the tried-and-true weakest defense of all: name-calling and vulgarity"

perhaps you can provide at least peer reviewed evidence supporting your accusations?







so, by definition, you're posting your opinion which is not supported by evidence - which is technically the same as a blatant lie with the "appeals to emotion" and very unscientific

so why is it OK for your argument?

you want to make a point that is against AGW, then provide the same level of evidence that scientists are providing which proves AGW - peer reviewed journal studies

in your case, you would need to refute the existing studies

i can wait...
4.6 / 5 (10) Mar 27, 2017
I repeat, the term "climate" has not been adequately defined.


Read, understand, comment, In that order please.
5 / 5 (7) Mar 27, 2017
Better still, take Captain
@earthling delusional troll
so- you can't make an argument from evidence or science, therefore you choose to use "the tried-and-true weakest defense of all: name-calling and vulgarity"

perhaps you can provide at least peer reviewed evidence supporting your accusations?





Indeed Captain
(as always) he can't provide peer reviewed evidence, the crickets overwhelmingly loud in this and each of his ramblings, but what there is no dispute of is his chest thumping and tree swinging skills :D
4.1 / 5 (9) Mar 27, 2017
Sigh... Here we go again, It has been pointed out to you before but obviously your limited insight prevents you from any sort of comprehension, an absolute dumb statement used by you Again countless of times before in many different flavors.

The Very distant past Climate changes you are mentioning that spanned Millions of years was due to Natural Occurrences and earth was inhospitable, as it would be if Fossil fuels keep Artificially pump toxic gasses into the air speeding the next extreme climate event up unnaturally ! So what that means if you don't understand, it makes it even Worse.

And there were no people around in those millions of years of those extreme conditions. But Does this open your eyes ? My bet as always be the case, a resounding NO... ;)
5 / 5 (6) Mar 27, 2017
Indeed Nova, to add to what you say, the consequences as to interfering with the earth's natural climate cycles can be beyond imagination, now we have trillions upon trillions of unnatural toxic gasses pumped into the air and polluting our oceans and the endless pollution disposed into our rivers. It is like adding fuel to the fire.
5 / 5 (9) Mar 27, 2017
Read, understand, comment, In that order please.

Nowhere in that article is climate actually defined. It discusses "climate normals" and offers calculations to derive what those should be.

That's just the way things work I'm afraid, first define the normal and then measure the deviation from normal.
5 / 5 (11) Mar 27, 2017
So now "Earthling Too" demands a definition of the term "climate". Anyone with even a modest education would not need one. He asks if I have a degree in any scientific field. I do not. I am an Engineer. But I know far more about the scientific method, despite any diplomas, certificates, or degrees, than "Earthling Too". If "Earthling" claims to have a science degree, it must be of the mail order variety. The facts in the matter can be easily reviewed by even a casual observer, and the results are obvious. Those who cannot see this are blinded by their delusions. "Earthling Too" is simply a slave to his delusions, which he desperately must validate in an attempt to regain or maintain a fragile illusion of sanity.
Captain Stumpy
4.6 / 5 (10) Mar 27, 2017
Nowhere in that article is climate actually defined
@denier troll
well... so much for the "understand" part of the request
AGW is a political talking point, a new potential source of tax revenue and one more lever of power given to global bodies such as the UN to dictate to the rest of us
1- AGW has a specific definition = Anthropogenic Global Warming
that is based upon science and repeatedly validated empirical evidence like Lacis et al, Francis et al and many, many, many other studies that you're ignoring, like you did here: https://phys.org/...ied.html

2- just because politicians get involved doesn't mean the science is political (See also: anything nuclear)

3- taxes come from gov't and politicians, not scientists

4- leverage and power come from the willingness of others to give up their control and are usually exercised by gov'ts, etc


not one single argument from science from you
just emotional denier rhetoric
5 / 5 (8) Mar 27, 2017
Its all about validating delusions. "Earthling Too" must have a lot of them. They MUST be defended. Take your own advice, "Earthling", regarding making a well structured valid argument, or calling names. It appears you could use it.
Captain Stumpy
4.6 / 5 (10) Mar 27, 2017
@denier earthling troll cont'd
I don't know that I would categorize my statements here as "countless," since I only recently felt the need to sign up for comments to hopefully dispel some of the hazy logic and the clear lack of rational thinking displayed by some here
but you are making arguments from emotion and nonsensical interpretations of evidence rather than logic, science or anything else

it's also repeating denier rhetoric from various other biased delusional sites

If you have an argument to make, formulate it well and stick to things that can be validated or proven with links and references. Don't stoop to emotional arguments from a nonsensical perspective or blind adherence to dogma

if you disagree, provide the same level of evidence that science would require for refute - if you understand what that means

case in point: above definition of climate
as SteveS points out: "first define the normal and then measure the deviation from normal"
4.3 / 5 (12) Mar 27, 2017
@earthling (antigoracle sockpuppet)
You recently felt like creating YET another sockpuppet.
This must be the cracker of the day "hazy logic?" the only haze you've been showing was the haze you've been swinging through on trees.

Sorry ... about the insults, You bring it upon yourself, there is no other way to put it (which means it will continue ;)

There is unlimited proof of climate change, YOU are not going to get me to carry the ocean full of evidence to you, stop being lazy, google is your fiend. if you have an argument Present it
relentlessly, trying to bring sensless arguments to the table will always be exposed

You miss the point as always, Antigoracle sockpuppet, Unnatutral warming Interferes Unnaturally with the earth's natural Climate cycle.
4.3 / 5 (6) Mar 28, 2017
Dr. John Bates, formerly with NOAA, went on record to openly talk about it. Take it up with him.


Dr Bates was concerned with some procedural issues, not with the quality of the data. He was also wary of his critique being misused by people sceptical of AGW.

"That's where I came down after a lot of soul searching. I knew people would misuse this. But you can't control other people,"

How right he was
1 / 5 (4) Mar 28, 2017
" Earth's climate is always changing"

Yes, . . and for most of that time, life for us was impossible.

Want to go back?
4.4 / 5 (7) Mar 29, 2017
...Dr Bates was concerned with some procedural issues...

If you're going to selectively post a snippet of what he said and downplay the significance of the "procedural issues," which are part of the scientific method and include testing, analyzing the statistics and making informed conclusions, then you should at least read it in his own words here: https://judithcur...te-data/

Here's another selectively posted snippet because it's obvious you never bother to read the linked articles

"'Whistleblower' says protocol was breached but no data fraud"


Now I'd like to remind you why we're talking about Dr Bates

...and much of the data that is available has been doctored. Dr. John Bates, formerly with NOAA, went on record to openly talk about it. Take it up with him.

" I knew people would misuse this." Dr John Bates

4 / 5 (4) Mar 29, 2017
What's your bias then?

I'm not the one claiming that much of the data that is available has been doctored.

Dr Bates never claimed there was any data fraud and the paper has been backed up by multiple dependent studies, so how does this back up you claim? He himself was wary of his critique becoming a talking point for those sceptical of human-caused climate change, so if you have any issues with this I suggest you "Take it up with him."

5 / 5 (3) Mar 29, 2017
Ahaaa... So I see - "Earthling Too" is simply a new incarnation..... you've been on my ignore list for a long time, and just managed to sneak a few fecal regurgitations in.......
Captain Stumpy
4 / 5 (4) Mar 29, 2017
@science denier earthling-troll
stop calling people "science deniers"
a "science denier" is someone who actively refuses to accept valid and validated science due to a bias or delusional belief

considering your actions above (and here: https://phys.org/...ied.html ) then we have established direct evidence that you refuse to accept science for the sake of your beliefs

this is demonstrative of denial of science

- you refuse to accept the science but you cannot provide a scientific refute, only your belief and opinion

that is the very definition of "science denier"
Many professionals including myself disagree that it is MAN-MADE
many professionals?

you're going to argue that because you and some professionals deny the science then it's a valid argument?


since most *scientists who understand the science* say otherwise, then your opinion is not based on science, but dogma

again: proof of science denial
Captain Stumpy
4.2 / 5 (5) Mar 29, 2017
@science denier earthling-troll cont'd
What's your bias then?
ok, so lets look at this objectively
you stated the data is tampered with
Much of the data is skewed, much of it is massaged and adjusted as needed to fit an agenda
but you offer no actual evidence of this except your interpretations of an article (not a study)

so, where does Dr. Bates say the data was tampered with?
or even wrong, or fraudulent?

your quotes are his opinion based upon what evidence presented and validated?
(hint: none)

the only "tamper" mentioned on the site belongs to leo goldstein (re-quoted by two others)
and there is absolutely no evidence at all whatsoever for his claim other than his opinion


full stop

IOW - you are biased presenting a biased opinion with no evidence because you want to believe it's true

it's not my opinion either

you have just proven it above

5 / 5 (1) May 23, 2017
I would like a comment section for people that understand and accept the science behind AGW and then have another section for those that want to argue about it. I find it very hard to have productive conversations with these trolls. They are welcome to argue with anyone they want IF that person really wants to engage them. All for it. I would rather this be a science site though.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.