Claim: Climate change makes summer weather stormier yet more stagnant

Study finds rising temperatures feed more energy to thunderstorms, less to general circulation.

From MIT:

Climate change is shifting the energy in the atmosphere that fuels summertime weather, which may lead to stronger thunderstorms and more stagnant conditions for mid-latitude regions of the Northern Hemisphere, including North America, Europe, and Asia, a new MIT study finds.

Scientists report that rising global temperatures, particularly in the Arctic, are redistributing the energy in the atmosphere: More energy is available to fuel thunderstorms and other local, convective processes, while less energy is going toward summertime extratropical cyclones — larger, milder weather systems that circulate across thousands of kilometers. These systems are normally associated with winds and fronts that generate rain.

“Extratropical cyclones ventilate air and air pollution, so with weaker extratropical cyclones in the summer, you’re looking at the potential for more poor air-quality days in urban areas,” says study author Charles Gertler, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “Moving beyond air quality in cities, you have the potential for more destructive thunderstorms and more stagnant days with perhaps longer-lasting heat waves.”

Gertler and his co-author, Associate Professor Paul O’Gorman of EAPS, are publishing their results this week in the Proceedings of the National Academy of Sciences.

A shrinking gradient

In contrast to more violent tropical cyclones such as hurricanes, extratropical cyclones are large weather systems that occur poleward of the Earth’s tropical zone. These storm systems generate rapid changes in temperature and humidity along fronts that sweep across large swaths of the United States. In the winter, extratropical cyclones can whip up into Nor’easters; in the summer, they can bring everything from general cloudiness and light showers to heavy gusts and thunderstorms.

Extratropical cyclones feed off the atmosphere’s horizontal temperature gradient — the difference in average temperatures between northern and southern latitudes. This temperature gradient and the moisture in the atmosphere produces a certain amount of energy in the atmosphere that can fuel weather events. The greater the gradient between, say, the Arctic and the equator, the stronger an extratropical cyclone is likely to be.

In recent decades, the Arctic has warmed faster than the rest of the Earth, in effect shrinking the atmosphere’s horizontal temperature gradient. Gertler and O’Gorman wondered whether and how this warming trend has affected the energy available in the atmosphere for extratropical cyclones and other summertime weather phenomena.

They began by looking at a global reanalysis of recorded climate observations, known as the ERA-Interim Reanalysis, a project that has been collecting available satellite and weather balloon measurements of temperature and humidity around the world since the 1970s. From these measurements, the project produces a fine-grained global grid of estimated temperature and humidity, at various altitudes in the atmosphere.

From this grid of estimates, the team focused on the Northern Hemisphere, and regions between 20 and 80 degrees latitude. They took the average summertime temperature and humidity in these regions, between June, July, and August for each year from 1979 to 2017. They then fed each yearly summertime average of temperature and humidity into an algorithm, developed at MIT, that estimates the amount of energy that would be available in the atmosphere, given the corresponding temperature and humidity conditions.  

“We can see how this energy goes up and down over the years, and we can also separate how much energy is available for convection, which would manifest itself as thunderstorms for example, versus larger-scale circulations like extratropical cyclones,” O’Gorman says.

Seeing changes now

Since 1979, they found the energy available for large-scale extratropical cyclones has decreased by 6 percent, whereas the energy that could fuel smaller, more local thunderstorms has gone up by 13 percent.

Their results mirror some recent evidence in the Northern Hemisphere, suggesting that summer winds associated with extratropical cyclones have decreased with global warming. Observations from Europe and Asia have also shown a strengthening of convective rainfall, such as from thunderstorms.

“Researchers are finding these trends in winds and rainfall that are probably related to climate change,” Gertler says. “But this is the first time anyone has robustly connected the average  change in the atmosphere, to these subdaily timescale events. So we’re presenting a unified framework that connects climate change to this changing weather that we’re seeing.”

The researchers’ results estimate the average impact of global warming on summertime energy of the atmosphere over the Northern Hemisphere. Going forward, they hope to be able to resolve this further, to see how climate change may affect weather in more specific regions of the world.

“We’d like to work out what’s happening to the available energy in the atmosphere, and put the trends on a map to see if it’s, say, going up in North America, versus Asia and oceanic regions,” O’Gorman says. “That’s something that needs to be studied more.”

This research was supported by the National Science Foundation.

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66 thoughts on “Claim: Climate change makes summer weather stormier yet more stagnant

    • Things I liked about this study is they considered “energy in the atmosphere” and “satellite and weather balloon measurements of temperature and humidity.” These findings could be relevant irregardless of cause (GHG, solar, etc., etc.). I realize they use a model and polar data which is sparse so I take this w/ grain of salt.

  1. I love how almost every study such as this that claims to link natural weather patterns to Man Made Climate Change always end with, please send more money. They always pretend to know the causes all the way until that last sentence or 2. Then say we do not fully understand and if you send us more money we will put out another paper claiming proof of man made climate change and again ask you for more money.

    • To be fair, Bill, I don’t see anything in the piece about Man Made. The climate changes all the time.

      On the other hand, I thought “the science is settled”

  2. “Climate change is shifting the energy in the atmosphere that fuels summertime weather”

    Large scale land use change and UHI have as much or more to do with providing this fuel in the mid latitudes of the Northern Hemisphere as does any long term changes from CO2 AGW. Subtract out the Land Use and UHI, and there is that much less CO2 available for being responsible for anything. And nobody is talking much about arresting UHI or land use change in the scheme of things.

  3. I’m sure the science and methods are sound. The researchers are savvy enough to check off the three pillars of future funding:

    “But this is the first time anyone has…”
    “…that connects climate change to…”
    “That’s something that needs to be studied more.”

    • I am not so sure: “They then fed each yearly summertime average of temperature and humidity into an algorithm, developed at MIT.” They don’t dare to call it a “model”. An algorithm?

  4. The expression “robustly connected” belies the prolific use of terms like “may, could, potential, likely, etc.,” all conveying inexactitude.

    Unfortunately, not atypical of “climate research” as it has evolved over the years!

  5. The article says,
    “In recent decades, the Arctic has warmed faster than the rest of the Earth, in effect shrinking the atmosphere’s horizontal temperature gradient. Gertler and O’Gorman wondered whether and how this warming trend has affected the energy available in the atmosphere for extratropical cyclones and other summertime weather phenomena.”
    That could be a natural or and athropogenic effect.

    VERY IMPORTANTLY the article also says,
    “Since 1979, they found the energy available for large-scale extratropical cyclones has decreased by 6 percent, whereas the energy that could fuel smaller, more local thunderstorms has gone up by 13 percent.”
    That seems to be a net benefit.

    Richard

    • I suppose that depends on how much you like thunderstorms. Me, I enjoy a good thunder-boomer when snug inside the house. The dogs, on the other hand, not so much.

  6. As usual the first sentence includes “which may lead to”. The last sentence states “ needs to be studied more “ as in more money. This means everything inbetween is BS.

  7. The way summers have been getting shorter and winters longer over the last few years, I just hope summer comes back this year.

  8. Ha! The US just had it’s first year on record with no “violent tornadoes” . No EF-5 or 4s were seen, even on radar, in 2018 in the US. There was a single EF-4 recorded for Manitoba Canada and that was the ONLY “violent” tornado recorded for all of N. America last. This despite the ever expanding coverage of ever improving radar. And then we get the tripe above?

    • It’s nice someone else picked up on this too! If more energy is being poured into local thunderstorms, the ones that spawn tornadoes, then why aren’t we seeing an increased number of tornadoes?

      How did this study manage to miss this obvious factor as an input?

      • Wind shear is a requirement for thunderstorms to develop into tornadic storms. Wind shear is a product of the horizontal temperature gradient. The lighter the gradient the less wind shear there is and the less likely a tornado will develop. The thunderstorms may be more plentiful but will only produce heavy rains or hail, and will dissipate more quickly without the wind shear to keep them going.

        • Some of the most destructive tornadoes in history have formed when there was very little temperature variation.
          https://www.nssl.noaa.gov/education/svrwx101/tornadoes/

          “How do tornadoes form?
          The truth is that we don’t fully understand. The most destructive and deadly tornadoes occur from supercells, which are rotating thunderstorms with a well-defined radar circulation called a mesocyclone. (Supercells can also produce damaging hail, severe non-tornadic winds, unusually frequent lightning, and flash floods.) Tornado formation is believed to be dictated mainly by things which happen on the storm scale, in and around the mesocyclone. Recent theories and results from the VORTEX2 program suggest that once a mesocyclone is underway, tornado development is related to the temperature differences across the edge of downdraft air wrapping around the mesocyclone. Mathematical modeling studies of tornado formation also indicate that it can happen without such temperature patterns; and in fact, very little temperature variation was observed near some of the most destructive tornadoes in history on 3 May 1999. We still have lots of work to do.”

        • The wind shear does not have to be from horizontal temperature gradient between latitudes. It can also come from vertical temperature gradients, i.e. warm, humid air in the lower atmosphere and colder, dryer air in the upper atmosphere. As you get increased energy into the thunderstorm, pushing the warm humid air up it eventually reaches a tipping point where things become unstable. You wind up with updrafts and downdrafts which then cause the rotating within the storm that leads to tornadoes.

          Your first reference states: “Not all supercells produce tornadoes. It still remains uncertain whether tornadic storms develop in a shear environment markedly different from nontornadic severe thunderstorms and whether the intensity of tornadic storms is related to the amount of wind shear. However, there is evidence that the character of vertical wind shear, especially the near ground layer, does play a significant role in tornado development. Strong winds in the mid- to upper levels are suggested to be associated with significant tornadoes”

          The second reference has equations using the partial differential of velocity to “z”, the vertical axis, not “y”, the horizontal axis. In fact, it states: “A supercell typically has a mesocyclone that may be influenced by the interaction of the storm updraft with the vertical shear of the environmental airflow:”

          Your third study says: “This study focuses on the evolution of three severe convective storms that spawned tornadoes in Alberta.” It doesn’t focus on wind shear from temperature gradients between latitudes.

          What gets me is where in this study is the decreasing number of cooling-days in the central plains factored in when it comes to the severity of thunderstorms? Any western Kansas or Nebraska farmer can tell you that days with cooler maximum temperatures produce fewer severe thunderstorms and therefore fewer tornadoes. And every summer states like Kansas, Nebraska, and Iowa are seeing fewer and fewer days where temperatures reach 100degF.

          • Thanks for taking the time to read through the articles. I think you are referring to the Storm Relative Helicity (SRH) equation with the differential in “z”. This is the vertical shear of the horizontal wind vector, which is the change in the horizontal wind (both speed and direction) with height. This is common nomenclature for vertical wind shear in meteorology. The horizontal wind is a product of the horizontal temperature gradient.

      • The narrative is that it isn’t causing more tornadoes…but when they do appear, the chance of having multiples (i.e., a “pack of tornadoes”) is increasing.

        • LOL! I guess they never heard the term “tornado outbreak”? So, if we have a very active tornado season this year or any of the next several years is their claim BS? Can it be falsified by tornado incidence or power?

          I’m bookmarking this one because I gotta feeling that there is a good chance that this year is going to pretty active and it’s going to be proven to be pure dung.

      • They also analyzed the summer season. Arctic winter temps have increased, but summer temps not so much. Most of what they say as background understanding of how things work is the same as what I was teaching uni students in the 70s. I will take the time to see how they derived the 6% and 13% values. There are a lot of hot humid summer days when there is nothing to trigger convection. It is not that simple.

      • The differential of the horizontal wind with respect to the z axis is certainly the vertical wind shear. That’s the whole point. It is the vertical wind shear that is the controlling factor, not the speed of the horizontal wind itself.

        You can have a high vertical gradient even with a low absolute horizontal speed.

        And, as I pointed out, I’m not sure the lower horizontal speeds are from higher arctic temperatures or lower central plains temperatures. The study doesn’t consider all the causal factors.

    • More thunderstorms does not necessarily mean more tornadoes, especially more violent tornadoes. For one thing, major tornadoes require that their parent thunderstorms form in a wind sheer environment that, when it has a vertical temperature profile and mosture favorable for thunderstorms, is typically found in a strong extratropical cyclone.

      Warmer temperatures, with the surface warming more than the upper troposphere and the Arctic warming more than the tropics, favors more and wetter thunderstorms but fewer/weaker severe thunderstorms and major tornadoes.

      • Strong tornadoes are driven by the jet steam configuration.

        When the jet stream is blowing from the southwest U.S. to the northeast U.S., like it is now, with the Pineapple Express subtropical jet stream (marked).

        Storms that move along this jet stream path tend to produce strong tornadoes

        We now have two jet streams converging over the U.S., the polar jet and the subtropical jet, which probably has some additive effect.

        In the warmer months of May and June this kind of jet stream configuration (mius the polar jet) would spark big tornadoes.

        https://earth.nullschool.net/#current/wind/isobaric/500hPa/orthographic=-84.37,37.02,401.

  9. “which may lead to stronger thunderstorms”

    Lets spend money for meaningless speculation. You haven’t tied anything to anything else. Put it on the 97% stack

  10. “Climate change is shifting…” Bullshit already, on multiple levels – first, their “use” of that term is undoubtedly presuming “human caused” change, which has not been established, and ALSO undoubtedly presumes “CO2 caused,” regardless of source, which has never been established by any scrap of empirical evidence. So they start with a massive presumption of causation that is not evident just because they noted some change in weather patterns.

    “More energy is available to fuel thunderstorms and other local, convective processes, while less energy is going toward summertime extratropical cyclones”

    – OR –

    “In the winter, extratropical cyclones can whip up into Nor’easters; in the summer, they can bring everything from general cloudiness and light showers to heavy gusts and thunderstorms.”

    So which is it?! MORE thunderstorms or LESS thunderstorms?! They’re talking out of both sides of their mouths! Now, no matter what happens, they can point to their “published paper” and say “See, just like we said.”

    And HERE’s the kicker –

    “Extratropical cyclones feed off the atmosphere’s horizontal temperature gradient — the difference in average temperatures between northern and southern latitudes. This temperature gradient and the moisture in the atmosphere produces a certain amount of energy in the atmosphere that can fuel weather events. The greater the gradient between, say, the Arctic and the equator, the stronger an extratropical cyclone is likely to be.”

    Whoa! They’ve just admitted that the weather in a warmer climate the weather will be MILDER than in a colder climate. Remember THAT!

    Oh and “recent decades” (very squishy time frame, that!) is conflated with “since the ‘70s” in terms of what they are “studying” (defined as “what they are sifting through in search of “bad” news”).

    “the team focused on the Northern Hemisphere…” OH! So it’s just a “regional effect,” then – nothing to see here, folks, you can all go home now. Oh I forgot, that “standard” of things having to be “global” only applies to those who aren’t PUSHING PROPAGANDA.

    “They then fed each yearly summertime average of temperature and humidity into an algorithm, developed at MIT, that estimates the amount of energy that would be available in the atmosphere, given the corresponding temperature and humidity conditions.” – And THERE it is folks, no ACTUAL data on the number or severity of thunderstorms or other “convective” processes, just apply some “MANNian math” and “presto,” “bad news” for the Climate Nazi gristmill!

    “Their results mirror SOME recent evidence in the Northern Hemisphere (as Don Rickles said in “Kelley’s Heroes,” “Hey, hey I found one!”), SUGGESTING (now THERE’s a ringing endorsement of a FIRM “conclusion” lol) that summer winds ASSOCIATED WITH (so “guilt by association” then) extratropical cyclones have decreased with global warming. OBSERVATIONS (hey, TWO is plural, isn’t it? It’s almost shocking that “observations” are even included – but don’t bother to say how many, or from where, or what proportion of the total “observations,” etc. because that might interrupt the march to the conclusion they STARTED with) from Europe and Asia (you know, OTHER THAN the “northern hemisphere,” which was supposedly what this pseudo-study was “focused” on) have also shown a strengthening of convective rainfall, such as from thunderstorms (which, by their own words, should be increased AND decreased – so there’s THAT).

    “Researchers are finding these trends in winds and rainfall that are PROBABLY related to climate change,” – LMFAO, couldn’t POSSIBLY be anything ELSE, or funding would instantly be cut off!

    I can’t even express how furious I am that my tax dollars continue to be squandered to produce utter garbage like this.

  11. Being poorly known, the ion chemistry of the lower stratosphere is generally ignored, or treated as similar to that of the middle atmosphere, by the current chemistry-climate modes. Some recent achievements in atmospheric chemistry have motivated us to re-asses the ionization efficiency of galactic cosmic rays (GCR) and ion-molecular reaction initiated by them. We reveal that near to the maximum of the GCR absorption, the energetically allowed ionmolecular reactions form an autocatalytic cycle for continuous O3 production in the lower stratosphere. The amount of the produced ozone is comparable to the values of the standard winter time O3 profile. This is an indication that GCR are responsible for a greater part of the lower stratospheric ozone variability then is assumed currently.
    https://www.researchgate.net/publication/235944643_An_Autocatalytic_Cycle_for_Ozone_Production_in_the_Lower_Stratosphere_Initiated_by_Galactic_Cosmic_Rays
    https://cosmicrays.oulu.fi/webform/monitor.gif
    https://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/gif_files/gfs_t100_sh_f00.png
    During periods of low solar activity, the ionization in the lower stratosphere over the polar circle increases as a result of the increase in galactic radiation. As a result, the temperature in the lower stratosphere increases over the polar circle. This results in the inhibition of circulation.

  12. These clever researchers are describing things the hard way toward what ought to be an obvious point made often here at WUWT: Thunderstorms are a very powerful and available feedback mechanism. The atmosphere sees to it automatically that excess heat is never actually “trapped” for long at the surface.

  13. Nonlinear analyses of the total ozone galactic cosmic rays (GCRs) and Sunspot numbers for the last 85 years reveal that ozone response to the variation of solar irradiance and GCRs is far from our current understanding for a linear relation between the forcing factors and responding parameter. We show that ozone variations depend more significantly on the multi-decadal variability of GCRs and solar irradiance than to their short-term fluctuations related to the 11-year solar cycle, interannual, etc., variability. Multi-decadal variations of the forcing parameters act as a commutator switching between different regimes of O-3 response to the short-term variations in GCRs and sunspot numbers. This convoluted dependence cannot be detected and described by linear statistical models. A nonlinear regression model of ozone dependence on the GCRs variability reveals that the combination of long- and short-term variations of the latter are able to describe 55% of the Arosa total ozone variability for the last 85 years. This is much more than and equivalent effective stratospheric chlorine (EESC) or, the solar irradiance variations are capable of explaining. In a prediction mode the GCRs nonlinear model estimates an increase of the ozone concentration during the current 24th solar cycle, unlike the EESC model, which shows levelling of the total ozone till the end of the current decade. The latter shows that the expectations of IPCC and WMO for a continuous weak enhancement of stratospheric O-3 – due to a reduced concentration of chlorofluorocarbons – need a reassessment, because the actual driver of ozone recovery is the continuously increased GCR flux intensity (consequence of a decreasing solar activity). All these findings are begging a general revision of our understanding for the processes controlling the ozone variability and its influence on the climate.
    https://www.researchgate.net/publication/282771318_NONLINEAR_RE-ASSESSMENT_OF_THE_LONG-TERM_OZONE_VARIABILITY_DURING_20TH_CENTURY

  14. “…summer winds associated with extratropical cyclones has decreased…”

    Does this mean we can stop throwing up wind turbines because their efficiency will drop from “terrible” to “unsupportable?”

  15. At least this study is in line with basic meteorology, unlike all of those studies that call for more severe weather with a decreasing temperature gradient. These clever authors avoided the topic of severe weather entirely, and spoke only of energy.

    Almost all severe weather in the mid-latitudes is associated with subtropical cyclones. Increasing the energy of individual thunderstorms probably won’t lead to an increase in severe weather, as airmass thunderstorms lack of the atmospheric dynamics to become severe.

    What this paper is really showing is that climate change over the last several decades has led to less severe weather in the summer months in the mid-latitudes. Good news however does not earn anyone future grant money. it is interesting how they try to spin this to make it into a problem.

    • Exactly. The cyclones they mention are what I assumed to be standard frontal systems aka low pressure systems. These probably contain 1000x times or more energy than standard convective storms and last days instead of hours.

      A 6% decrease in the cyclones probably equates to far more Hiroshimas than the 13% increase in convective thunderstorms. I think this press release was trying to hide the fact this means less extreme weather.

      • As famous physicist Freeman Dyson has pointed out, many climate studies, such as this one, lack the breadth of scope needed to fully describe the environment we know as Earth.

        This study makes one major assumption, that the Arctic has warmed, which has resulted in a decreased temperature gradient between the mid-latitudes and the arctic thus giving lower horizontal wind forces and resulting in less energy being available to create intense tornadoes.

        The central plains from KS/MO north, however, have been identified as being a global warming hole, where maximum summertime temperatures are actually moderating. This also creates a decreased temperature gradient for when low pressure systems move through the central plains. Lower surface temperatures meeting cold fronts also mean less intense tornadoes but this study doesn’t even address this factor let alone try to control for it in the study.

        This is probably a contributing factor as to why “tornado alley” seems to have moved southward to OK , AR, North TX , and points east at least as far as EF4/5 tornadoes are concerned.

        If you don’t consider the totality of the environment when it comes to climate then all you are doing at best is proving partial causation and at worst nothing more than correlation.

  16. Is the Arctic really warming etc etc? Looks pretty cool on earth.nullschool.net and those little green graphs one sees

  17. I continue to believe that average temperatures tell you nothing about what is available at any given time anywhere to do anything.

    As for feeding it an algorithm, using “algorithm” doesn’t mean it isn’t a bunch of assumptions made by the researchers. So if the researchers assumptions are right, their theory might be right. But using your assumptions doesn’t prove your theory. You have to prove your assumptions are right.

    • Averages tell you absolutely nothing. An average can go up because maximum values went up. An average can go up because minimum values went up. An average can go up because mid-range values went up. An average can go up because any possible combination of all three can happen.

      An average is like a magician’s hat. You can pull out any color of rabbit you want. Who’s to say it’s the wrong color rabbit? The problem is that the converse is also true but no one will admit it. How do you prove that it is the right color of rabbit?

  18. Whilst its obvious that heat and also of course a lack of heat, ie cold, , move around, but para two says the usual , that Global temperatures ,are increasing.

    Who says ? and if so by how much. ?

    MJE

  19. “Extratropical cyclones ventilate air and air pollution, so with weaker extratropical cyclones in the summer, you’re looking at the potential for more poor air-quality days in urban areas,” says study author Charles Gertler, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).

    Or maybe you get a quicker rain-out of local pollution. Or maybe it gets convected up towards the higher velocity air streams at altitude, which then quickly distribute it away. They need to build a model that works.

    This is, or ought to be, almost the entire raison d’etre of climate/weather models. They do have value, potentially. But these wankers just come out with “how can we twist it to come up with something bad, even though we really just don’t know what will happen”.

  20. So the poles are warmer. It could be CO2. Or, it could be that the unstable polar vortex means sub-vortexes break off and head southward to be replaced by warmer air from the south. With the warmer air the poles, as well as the earth overall, becomes a better radiator. Seems to me that this better pole-to-equator heat transport means less temperature contrasts and fewer tornados and hurricanes, which is what we are seeing.

  21. From the article: “Scientists report that rising global temperatures, particularly in the Arctic, are redistributing the energy in the atmosphere”

    Except those scientists are out of date. The temperatures are in fact, falling, not rising. They have been falling since Feb. 2016. Time to reassess your study. Let us know what happens when scientists report falling global temperatures. That would be more relevant to today.

    See for yourself. Here’s the UAH satellite global temperature chart

    https://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_January_2019_v6.jpg

  22. So stronger cyclones is bad. more wind, stronger hurricanes, and weaker cyclones is bad because of less wind worse air quality.

    Cant these people stop talking crap and making utter fools of themselves?

  23. That’s interesting, because it’s EXACTLY what Willis Eschenbach uses to tell us since, like, forever already, when he’s talking about thunderstorms being the single, most-important control knob for Earth’s climate to get rid of excessive heat in the atmosphere. Kudos, Willis!

  24. Just another study that takes a bunch of data and churns it through an algorithm which creates a buttery result. That result isn’t the actual butter of a verified hypothesis but, at best the possible basis for a hypothesis.

  25. Garble google doogal. It just get more ridiculous every day. All of these studies claiming this and claiming that and we still have no clue.

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