Weather extremes: Humans likely influence giant airstreams

March 27, 2017
A composite image of the Western hemisphere of the Earth. Credit: NASA

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. These planetary waves transport heat and moisture. When these planetary waves stall, droughts or floods can occur. Warming caused by greenhouse gases from fossil fuels creates favorable conditions for such events, an international team of scientists now finds.

"The unprecedented 2016 California drought, the 2011 U.S. heatwave and 2010 Pakistan flood, as well as the 2003 European hot spell all belong to a most worrying series of extremes," says Michael Mann from the Pennsylvania State University in the U.S., lead author of the study published in Scientific Reports. "The increased incidence of these events exceeds what we would expect from the direct effects of global warming alone, so there must be an additional climate change effect. In data from computer simulations as well as observations, we identify changes that favor unusually persistent, extreme meanders of the jet stream that support such . Human activity has been suspected of contributing to this pattern before, but now we uncover a clear fingerprint of human activity."

How sunny days can turn into a serious heat wave

"If the same weather persists for weeks on end in one region, then sunny days can turn into a serious and drought, or lasting rains can lead to flooding," explains co-author Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research (PIK) in Germany. "This occurs under specific conditions that favor what we call a quasi-resonant amplification that makes the north-south undulations of the jet stream grow very large. It also makes theses waves grind to a halt rather than moving from west to east. Identifying the human fingerprint on this process is advanced forensics."

Air movements are largely driven by temperature differences between the Equator and the Poles. Since the Arctic is more rapidly warming than other regions, this temperature difference is decreasing. Also, land masses are warming more rapidly than the oceans, especially in summer. Both changes have an impact on those global air movements. This includes the giant airstreams that are called planetary waves because they circle Earth's Northern hemisphere in huge turns between the tropics and the Arctic. The scientists detected a specific surface temperature distribution apparent during the episodes when the planetary waves eastward movement has been stalling, as seen in .

Using temperature measurements since 1870 to confirm findings in satellite data

"Good satellite data exists only for a relatively short time—too short to robustly conclude how the stalling events have been changing over time. In contrast, high-quality temperature measurements are available since the 1870s, so we use this to reconstruct the changes over time," says co-author Kai Kornhuber, also from PIK. "We looked into dozens of different climate models—computer simulations called CMIP5 of this past period—as well as into observation data, and it turns out that the temperature distribution favoring planetary wave airstream stalling increased in almost 70 percent of the simulations since the start of the industrial age."

Interestingly, most of the effect occurred in the past four decades. "The more frequent persistent and meandering Jet stream states seems to be a relatively recent phenomenon, which makes it even more relevant," says co-author Dim Coumou from the Department of Water and Climate Risk at VU University in Amsterdam (Netherlands). "We certainly need to further investigate this—there is some good evidence, but also many open questions. In any case, such non-linear responses of the Earth system to human-made warming should be avoided. We can limit the risks associated with increases in if we limit greenhouse gas emissions."

Explore further: Trapped atmospheric waves triggered more weather extremes

More information: Michael E. Mann, Stefan Rahmstorf, Kai Kornhuber, Byron A. Steinman, Sonya K. Miller, Dim Coumou (2017): Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events. Scientific Reports, DOI: 10.1038/srep45242 , http://www.nature.com/articles/srep45242

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19 comments

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MR166
1.5 / 5 (8) Mar 27, 2017

"The unprecedented 2016 California drought, the 2011 U.S. heatwave and 2010 Pakistan flood, as well as the 2003 European hot spell all belong to a most worrying series of extremes," says Michael Mann from the Pennsylvania State University in the U.S., lead author of the study published in Scientific Reports."

Unprecedented 2016 drought my a$$! The fact that Mann is considered a leader in the climate science field is a stinging rebuke to the fields credibility.
gkam
2.8 / 5 (11) Mar 27, 2017
Don't you feel more and more isolated with those reactionary views?

The world of science has accepted the overwhelming evidence, but I see others cannot. I think it is pretty well settled, and we have to take action last century.
EarthlingToo
1.7 / 5 (11) Mar 27, 2017
There is no "overwhelming evidence." There is ongoing debate based on data not just from the last few hundred years but based on global trends since the supposed last Ice Age.

No one has satisfactorily defined what "climate" really is. That the weather changes is a given, but how man's activities may or may not influence that change is a very contentious topic and not at all "settled science."

Repeating unfounded claims do not increase their value.
gkam
2.6 / 5 (10) Mar 27, 2017
Well, "Earthling", I studied this for an MS decades ago, and watched as things got much worse faster than originally feared.

We did not anticipate the general scientific ignorance nor the ability of politicians in hand with Big Business to manipulate the emotions of their "base".
EarthlingToo
2.1 / 5 (11) Mar 27, 2017
The only politicians you should be worried about are those trying to pass various "carbon taxes" on everyone else, along with the UN which wants to enforce global climate change policies. Leave politics aside.

The data is faulty and has been proven to be massaged at the highest levels. It has been twisted to fit the agenda. Do your own research and approach the topic as a true scientist.
gkam
2.3 / 5 (9) Mar 27, 2017
I am not a scientist, I did practical work in several industries.

I think much of the Denier Syndrome comes from emotional manipulation by political manipulators.

Ever notice they are the same folk who fell for "WMD!"?
TheGhostofOtto1923
3.3 / 5 (7) Mar 27, 2017
Well, "Earthling", I studied this for an MS decades ago, and watched as things got much worse faster than originally feared
George kamburoff the lying cheating psychopath took no courses and studied nothing to get his storebought honorary MS for lifetime achievement.

I did not know they gave out merit badges for accomplishments in creative lying.

George has been here for months peddling the same garbage as if nobody here has found out what he really is and does.
RealityCheck
3.3 / 5 (7) Mar 27, 2017
Hi Ghost. :)

And what are your 'accomplishments' in life and on the net, Ghost? Stalking, lying and 'projecting' your own 'creepy' character flaws onto those who haven't wasted/betrayed their intellect, science and humanity like you still seem determined to do. Why? Stop it, mate! Be better than this. Your intellect, science and humanity need you to be better than this. Don't keep wasting your life like an Internet Loser does with behavior like that which you are 'presenting' here at PO. Concentrate on the science, not the person, Ghost. That is the only way to avoid becoming irretrievably 'lost to reason and decency'...and eventually ending your life in the tragic manner of all "Internet Losers" (which will be your epitaph if you keep this 'creepiness' up). Wake up, Ghost! :)
snoosebaum
5 / 5 (2) Mar 27, 2017
''I think much of the Denier Syndrome comes from emotional manipulation by political manipulators. ''

in my case it comes from an reasonable response to the attempted Media manipulation of the US election , an extreme example of their manipulation of every important issue as long as i can remember. The establishment is entirely suspect/corrupt in my view now. So you are correct about ' political manipulators' you just picked the wrong ones.
howhot3
4.4 / 5 (7) Mar 27, 2017
Just read the article. Basically the article claims that global warming has created pockets highs and lows that pins the jet stream to a specific undulating pattern, which pins extreme weather patterns to certain locations. I think this past winter was a prime example of this. Not only has global warming trapped the arctic air mass to the north, the pinned jet stream kept it that way for the most part. That's why the big separation between North and South persisted all winter. The undulations of the jet stream were very slow to move.

"Trapped atmospheric waves triggered more weather extremes" Nature 2017. Michelle Mann et al. That speaks volumes over the little twit no-nothing deniers.
cantdrive85
1.5 / 5 (8) Mar 27, 2017
Mann and all of his AGWite acolytes couldn't be more wrong about what drives these systems. The Earth's electromagnetic circuit system interacting with the Sun's electrodynamic plasma environment is what drives these systems. Computer games with faulty knowledge just results in fanciful imaginings of the pseudoscientists. Until it is realized the electrodynamic properties of the Sun-Earth connection which are primary and all the processes they rely upon for their faulty models are the result, they will continue to arrive at faulty conclusions.
howhot3
4.5 / 5 (8) Mar 27, 2017
Actually @Can't, you and your denier goons are even more wrong "Mann and all of his AGWite acolytes couldn't be more wrong about what drives these systems". Mann and his group actually look at stuff... you denier goons don't. I mean, we see these scientists work their butts off collecting data by all kinds of means, they publish the data and will tell you where and how they got it. BUT you deniers are no where to be seen. Where is your denier lab? All we hear are CRICKETS when it comes to showing your data! You deniers are FAKE! Fake news! Deniers are fake phoney dimwit buttheads!

I dare you to write a comment about this article, it's authors, and send it to Nature. I dare you to write Nature. I double dog dare you!

Hell, just read the article if you can read. That would be exciting.

Whydening Gyre
5 / 5 (4) Mar 28, 2017
"The unprecedented 2016 California drought, ...

Now explain - the unprecedented downpours of 2017 that ended it...
Whydening Gyre
5 / 5 (2) Mar 28, 2017
Mann and all of his AGWite acolytes couldn't be more wrong about what drives these systems. The Earth's electromagnetic circuit system interacting with the Sun's electrodynamic plasma environment is what drives these systems.

Which are generated by - you guessed it - gravitational interaction of mass...
cantdrive85
2 / 5 (4) Mar 28, 2017
Which are generated by - you guessed it - gravitational interaction of mass...

As usual, your artistic impression has it backwards;
"What we call mass would seem to be nothing but an appearance, and all inertia to be of electromagnetic origin." Henri Poincaré, Science and Method
Sherrin
not rated yet Mar 28, 2017
Reading this article you could be excused for thinking jet streams (or planetary waves, whatever) only happen between the Arctic and the tropics: "Giant airstreams are circling the Earth, waving up and down between the Arctic and the tropics." Are jet streams no longer occurring in the southern hemisphere or what??
Whydening Gyre
5 / 5 (1) Mar 28, 2017
Which are generated by - you guessed it - gravitational interaction of mass...

As usual, your artistic impression has it backwards;
"What we call mass would seem to be nothing but an appearance, and all inertia to be of electromagnetic origin." Henri Poincaré, Science and Method

Well. You grave robber, you...
Didn't he die over a hundred years ago?
If so, doncha think we've picked up just a teensy more data on the matter (:-)) since then?
cantdrive85
1 / 5 (2) Mar 28, 2017
If so, doncha think we've picked up just a teensy more data on the matter (:-)) since then

No doubt! Since then we have learned 99.9999% of the known Universe is in the plasma state, which are electromagnetic systems explained by Maxwell-Boltzmann equations.
Captain Stumpy
3 / 5 (2) Mar 30, 2017
@nazi-sympathizing eu pseudoscience cult idiot
Mann and all of his AGWite acolytes couldn't be more wrong about what drives these systems
1- notice the references in this study?
some of them are validated science based upon measurement and observation, like Francis-Vavrus
unlike your unfounded eu cult claims, this isn't about speculation - it's backed by evidence that has been validated, ya moron

2- considering your eu cult has absolutely zero capability to make accurate predictions about astrophysics, let alone weather, your comment is actually almost comical in it's attempt to argue any point at all

the rest of that post (and everything else) is complete gibberish based upon your delusional belief, not upon any evidence at all whatsoever

here is a question: when are you going to actually produce some verifiable valid science studies from a reputable source or journal that makes the same claims you do?

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