That is the theme of this guest piece at Think Progress by climate scientist Brad Johnson (emphasis in original):

n an email interview with ThinkProgress, Dr. Kevin Trenberth, one of the world’s top climate scientists, who has been exploring for years how greenhouse pollution influences extreme weather, said he believes that it is “irresponsible not to mention climate change” in the context of these extreme tornadoes. Trenberth, head of the Climate Analysis Section of the National Center for Atmospheric Research, added that the scientific understanding of how polluting our atmosphere with billions of tons of greenhouse gases affects tornadic activity is still ongoing:

It is irresponsible not to mention climate change.The environment in which all of these storms and the tornadoes are occurring has changed from human influences (global warming). Tornadoes come from thunderstorms in a wind shear environment. This occurs east of the Rockies more than anywhere else in the world. The wind shear is from southerly (SE, S or SW) flow from the Gulf overlaid by westerlies aloft that have come over the Rockies. That wind shear can be converted to rotation. The basic driver of thunderstorms is the instability in the atmosphere: warm moist air at low levels with drier air aloft. With global warming the low level air is warm and moister and there is more energy available to fuel all of these storms and increase the buoyancy of the air so that thunderstorms are strong. There is no clear research on changes in shear related to global warming. On average the low level air is 1 deg F and 4 percent moister than in the 1970s.

Climate scientist Michael Mann, director of the Earth System Science Center at Pennsylvania State University, explains further that “climate change is present in every single meteorological event”:

The fact remains that there is 4 percent more water vapor–and associated additional moist energy–available both to power individual storms and to produce intense rainfall from them. Climate change is present in every single meteorological event, in that these events are occurring within a baseline atmospheric environment that has shifted in favor of more intense weather events.

There’s more at Think Progress.

Kathy Kattenburg
Leave a replyComments (19)
  1. DLS April 30, 2011 at 4:58 pm

    It’s irresponsible to be irresponsible “global warming” activists.

    “Climate change is present in every meteorological event”?

    Mann left out “economic,” “social,” “astronomical,” et cetera.

    I knew the barrel-bottom crowd would stir sometime…

  2. SteveK April 30, 2011 at 5:32 pm

    DLS said: “I knew the barrel-bottom crowd would stir sometime…”

    That’s a pretty nasty ad hominem to be throwing out DLS… I thought you’d stopped with this childish behavior.

    Was your comment aimed at Kathy? If not would [could?] you specify just who you are talking about or was your vile remark meant for anyone who accepts scientific evidence over your patently silly talking points?

  3. Indefatigably April 30, 2011 at 6:14 pm

    First, how in the world can you call DLS’ comment ‘vile? Engaging in a bit of hyperbole yourself, I think.

    Second, there is merit to his key point. The question is what ARE the effects of Global Warming (a separate question as to what is causing it), and does any climate model actually have any demonstrative prediction and forecasting ability?

    Last year was a wet and mild spring out here, this year dry and wicked hot. Last year’s wet but mild weather was caused by Global Warming, and lo and behold, this year’s hot and dry conditions are caused by (you guessed it) Global Warming!

    Last year was a relatively mild tornado season; this year is horrific.

    Last year was predicted (due to Global Warming) to be an especially bad hurricane season, with perhaps a record number of storms (actually, the last few years have had that same prediction, for the same reason). However, that was not the case.

    Mild winter? Global Warming causes those. Heavy snowfall this winter? Global Warming causes those. Bitter cold? Global Warming. Drought? Global Warming. Flooding? Global Warming.

    So, it seems no matter the type of weather at any given time, at any given place, it is always ‘because of Global Warming’ for some new reason or aspect of Global Warming.

    That to me seems obviously nothing more than trying to fit the facts to the thesis, rather than the other way around.

  4. davidpsummers April 30, 2011 at 7:35 pm

    OK, the fact is that climate change may lead to more events like this. It is equally true that you can’t link any one event to climate change and they will occur either way.

    So I would say that it is irresponsible to not try and give people a deeper understanding of the issue instead of simplistic attempts to “blame” climate change for any one event.

    Such attempt can even be counter productive. When you have a calm year, everyone will then link that to disproving climate change (since, after all, you have already conceded the idea that you can make such links).

    I know that people get frustrated with restraint, but it in the end it is the only thing that won’t simply get undermined later. Throwing anything at it, like the claim it will lead to more earthquakes, just doesn’t help.

  5. DLS April 30, 2011 at 7:42 pm

    It’s easy to call my comments “vile” or any other kind of nonsense — just choose to be nonsensical as well as ill-willed toward me or other heretics when it comes to “global warning” or other liberal gospels — and others who diverge from farther-left gossip mantra.

  6. SteveK April 30, 2011 at 8:00 pm

    Actually DLS two of the four sentences you wrote in your initial comment are well worth serious discussion and debate.

    Unfortunately you sandwich them between two, totally unnecessary, mean spirited, and (as always vague) insults against anyone that thinks differently than you.

    You seem to think your DLS Specials™ are cute… They’re not, they’re nonproductive and childish.

    Write like you’d like others to write about you and I’ll be glad to have a civil conversation.

  7. DLS April 30, 2011 at 8:39 pm

    Long comment — my critics need to read and learn…

    Indefatigably wrote:

    > The question is what ARE the effects of Global Warming
    > (a separate question as to what is causing it)

    At the risk of more bogus charges like “ad hominem” (or any other logical-fallacy term that lefties here misuse as part of their routine behavior), here is what could be expected from what we know about warming as well as prime reading material and useful hints. (I realize I could get banned for doing this while my misbehaving adversaries constantly are misbehaving and never admonished or worse; c’est la vie.) I’ve kept my comments short on the new comment system, but elaboration is in order here. Read and learn.

    The warming would primarily affect (raise) temperatures at night and in winter eventually (not now, eventually — decades from now, if ever, which is not guaranteed). Obviously, then, it stands to reason that in lieu of any other things we don’t know or haven’t been able to predict, the tornado season in the eastern USA would begin earlier, be longer, and arguably be more intense, too. The tornados occur primarily in the spring when there is a large contrast between cold, dry polar continental air and warm, wet tropical maritime air (which is found in the East, and begins to be warmer, and contain more water vapor, in the spring and into summer with the semi-permanent high pressure clockwise air flow from water bodies — the Gulf, Caribbean, Atlantic, and Gulf of California that provides the fuel for summer “monsoonal” thunderstorms in the Southwest). Anywhere where there is sufficient heating, there is the energy for thunderstorms, and the more humid East has a better set of conditions for generation of these storms throughout the year. (It’s no surprise the East has tornado warning sirens, with occasional testing to ensure the warning system is intact before tornados occur.)

    It obviously stands to reason that with most warming in the winter, and starting from a greater temperature (and absolute, at least, humidity) and increasing through the spring into summer, that the tornado season could begin earlier, last longer, and be more intense (at the point where the warmest maritime air would encounter cold polar air).

    (At the greatest extreme this means a possible increase in storms during the winter.)

    None of this is any excuse for hype, as Al Gore and so many far-leftists have done (with the complicity of ignorant and eager-to-believe other leftists), making ludicrous claims for tornado and hurricane frequency and intensity already having become greater.

    Here, again, is useful reading for people who want to know more, all the way to what is the realistic “worst case” stable-state future environment (unlikely, but possible), having the Arctic Ocean be ice-free year-round.

    Mueller’s treatment of “climate change” for layperson students remains one of the best. (Note that Mueller is currently running a surface temperature experiment to obtain better information than has been obtained from surface stations in the past. Also, I may add notes from Mueller’s paperback book about the subject, that includes the wrongful things the Left has been doing about this subject, including the notorious Al Gore, as a separate comment.)

    What is the worst case? It’s an ice-free Arctic. Others who also have read about climate as well as weather know who Hermann Flohn was. His report for IIASA in 1980, when the greenhouse effect and global warming first became a subject of interest (political as well as scientific) in academia remains the best. Any of you who are awake in these United States know about the semi-permanent highs off the East and West Coasts, and how they shift northward in summer, southward in winter, following global wind patterns (even more than following the sun). Flohn described what severe global warming, to the point where the Arctic Ocean were largely or completely free of ice year-round, would do to the climate: it would shift wind patterns and the semi-permanent highs northward in the Western Hemisphere. (Little or no change would occur in the Southern Hemisphere.) In his report, he includes references to evidence of vegetational shifts to the north and animal life shifts north accompanying a warming. See Figure 21 on page 59, and (more interesting — best) Figure 22 on page 60 to see climatic shifts northward in warmer, earlier times. Anyone familiar with climatology (Koppen, or Trewartha’s US derivation of climatic zone classifications and definitions) will at once grasp the shifting. Proceed then to page 61 to read the description of the effects of an ice-free Arctic Ocean. The last paragraph on page 63 begins the true-to-life description of what could happen.

    Here is Flohn’s report, still the best paper ever on major global warming consequences.

    Good reading.

  8. PATRICK EDABURN April 30, 2011 at 8:46 pm

    I think some of the comments illustrate the problem with debating hot button topics like climate change.

    For some you have to either think that climate change has absolutely no impact on things at all or you have to accept that nothing bad ever happens except for climate change.

    The truth of course is in between.

    Did bad storms happen before climate change ?

    Of course they did. One of the worst tornado outbreaks ever happened in the 1920’s.

    Did climate change play a role in this outbreak ?

    That one is a little harder to address in the sense that weather is a very very complex thing but the answer is most likely yes. Warmer weather will make weather systems more active.

    So climate change did play a role, but so did the normal cycle of weather. From time to time we do have bad storms, just as from time to time we have amazingly good weather.

    And the best part of all is both sides can be critical of my answer since I disagree with both of them in part…

  9. Dave Hemmann April 30, 2011 at 9:33 pm

    climate change is measured in decades at the least, and any yearly event cannot be pointed to as proof. the argument is not that the climate changes, it is that seasonal storms are not an indicator of that change.

    it’s like pointing at a single leaf and declaring the death of the entire tree. CO2 concentrations have actually gone down is the past few years, so the real question is just how much can be scientifically attributed to just CO2. Take a look at the 100000graph of climate on earth to study climate, don’t just pick an outbreak of bad weather to prove anything.

    and yes, let’s drop the name calling and culture warrior etiquette censorship.

  10. rudi April 30, 2011 at 10:28 pm

    Where did you get this?
    CO2 concentrations have actually gone down is the past few years, so the real question is just how much can be scientifically attributed to just CO2.
    Here’s a few links that say the opposite.
    Abo Akademi University

  11. JSpencer May 1, 2011 at 12:04 am

    Hey, I know, let’s just make everybody happy and fall back on the ever popular all things are equal “solution”!!! AGW is a real problem AND it’s bunk!!!

    Again, there have been 600 tornados this month, whereas the average for April is about 160. If that trend continues… well, let’s just hope it doesn’t.

  12. Dave Hemmann May 1, 2011 at 5:07 am


    I suggest that the hype has overrun common sense and good science. The number of tornadoes have not increased, but the sightings of said tornadoes has increased.

    From the Weather underground site:
    “Are the number of tornadoes increasing?

    The number of tornadoes that occur each year is not increasing, but the number of spotted and reported tornadoes is. The reason for this is that more people live in or travel through tornado prone areas than used to. This has led to better communication and reportings of severe weather.”

    It’s similar to reports of increased hurricane damage, the storms are as they’ve always been, but because beach fronts are cluttered with high priced homes, the dollar amount has soared. damage is more relational to real estate value and higher land use than from bad weather caused by the dreaded changing climate.

    Global temps have steadily climbed since The Little Ice Age, carbon dioxide has played a very small and finite part of that process. The problem with the alarmist view of a sudden surge in temps due to CO2 is that the theory requires that forcing factors other than CO2 must interact to amplify the 1.5 degrees of warming per century of carbon warming to be able to predict the 5-7 degree jump. No scientific proof of that interaction has ever been demonstrated, full stop.
    AGW is a theory that has shown no experiment that demonstrates the basic premise of it’s conjecture, and so it lacks the validation component of the scientific method.

  13. JSpencer May 1, 2011 at 12:37 pm

    Climate change is a complex phenomenon that is occurs on a planetary scale. It is best observed over time, not moments. Just as hype and alarmism can detract from our understanding of it, so can downplaying and ignoring it. Let’s hope the USA doesn’t end up being the country the drags it’s heels when it comes to taking the problem as seriously as it deserves.

  14. DLS May 1, 2011 at 5:01 pm

    Dave Hemmann: Not only is the tornado hype wrong because, yes, our ability to detect tornadoes is better, but it’s also the same with hurricanes. (A hype-remover with hurricanes is only to evaluate the situation with those hurricanes that have actually reached our shores, which is the same apples-to-apples, consistent way to look at hurricanes throughout our history, not just in modern times.)

    I may add that warning by Mueller about what the hypesters and hucksters on the Left have been engaging in (not limited to, but obviously including Al Gore’s political tactics). Perhaps tonight.

  15. Dave Hemmann May 1, 2011 at 6:47 pm


    But you demonstrate the very problem of using short-term data to predict long range trends. Since the 1998 “heat wave,” global temps have flattened out and even decreased while CO2 continues to be added to the atmosphere. If dragging one’s heels means that I insist upon a discernible trend, that’s science. counting tornado sightings is just another example of the weak case AGW presents.
    Add to that that Scientists who state they know the truth won’t release their data for objective verification again flout the most basic scientific principles.
    The AGW theory fails the most basic test of scientific principle, and a long as that’s the case, no action should be taken to attack a problem that may well not exist at all, or at least, may not exist in the way the problem is currently formulated. Theories must be tweaked to fir the data, the data should never be tweaked to fit the theory.

  16. DLS May 1, 2011 at 11:03 pm

    Dave Hemmann wrote:

    > Theories must be tweaked to [fit] the data[;]
    > the data should never be tweaked to fit the theory.

    1. From Mueller’s paperback book:

    [M]uch of what the public “knows” about global warming is based on distortion, exaggeration, or cherry picking. An example of distortion if the melting of the Antarctic ice — something that actually contradicts the global warming models but is presented as if it verifies them. Exaggeration includes the attribution of Hurricane Katrina [or, e.g., this spring’s tornado outbreak — DLS] to global warming, even though there is no scientific evidence they are related. Cherry picking is the process of selecting data that verify the global-warming hypothesis, but ignoring data that contradict it. …

    There is an irony here. The very reason that physics is so successful is that it holds a very high standard for determining truth. But in global warming, because the issue is so important, the standard has been lowered. …

    [An] example of distortion is found in the claim that the cost of hurricane damage has been rising exponentially because of global warming. … This … has been widely used, and a version of it appears in “An Inconvenient Truth.” It is highly misleading, however, because it shows costs without compensating for inflation. …

    [O]n TV, in “An Inconvenient Truth,” and in numerous articles and newspaper reports, … [h]ere is what people have learned from these sources: the evidence is overwhelming that the number of truly intense hurricanes [categories 4 and 5] has increased dramatically in the post 30 years. …

    The number of hurricanes that actually made landfall [an unbiased criterion for reportage and claims that are not distorted — DLS] shows no obvious trend up or down in the number of hurricanes hitting the United States, or in the number of intense (category 4 or 5) hurricanes. …

    In “An Inconvenient Truth,” Al Gore also states that the number of tornadoes has been increasing and attributes that worrisome fact to global warming. … The number of strong to violent tornadoes has been decreasing over the past 55 years. … The number of big [tornadoes] — the ones that do damage — is actually decreasing. That sounds good, so why mention only the total increase [due in large part because of changes and improvements in tornado detection — DLS], which sounds bad?

    Wildfires also provide another example of cherry picking. Al Gore states that the number of wildfires has been increasing, and he attributes that increase to global warming. … [T]he acres of burned land are indeed, increasing, but … the number of fires is actually decreasing. … [A] decrease in the number of fires and an increase in acreage could both be related to policy to let fires in the wilderness burn themselves out. …


    Al Gore won the Nobel Peace Prize because of his effectiveness in alerting the US public to the dangers of carbon dioxide and global warming. He was able to do this through a combination of artistry, powerful writing, and exaggeration, mixed with some degree of distortion and a large amount of cherry picking. His great movie “An Inconvenient Truth” is powerful propaganda, but as with all propaganda, there is a danger. When it is discovered that Gore has exaggerated the case, the public may reject the truly scientific case for fossil fuel-induced global warming. … I fear that the public may throw out the baby with the dirty bathwater.

    2. And what about the theory being data to fit a political theory, namely what “solutions” are sought that are the same as for other, earlier apocalyptic “problems” often by the same people?

    The following lecture evolved into a book. The lecture, with among the principal concepts the obvious superiority of adaptation to mitigation, in the Queen’s English, is superior to so, to much from the Other Side, appealing to what they lack so, so much.


  17. rudi May 2, 2011 at 12:35 am

    DH Please supply links from scientists to back up your claims of global temps and CO2 concentrations flattening or decreasing. A simple Google search shows the opposite of your claims.

  18. DLS May 2, 2011 at 7:57 pm

    Rudi, global temps have stalled for at least a few years. Perhaps that’s due to the economic slump affecting the west (and maybe China before any problems there would ever be revealed or be admitted by the Chinese government), but in any case this is well known — this is common knowledge(!).

    I also hope you as well as Dave H. read my earlier posting that quoted Muller’s paperback as well as linked to Nigel Lawson’s lecture about global warming and energy and industrial and economic policy that later became a book. I looked just now and got the note that that posting is (still!) in moderation, which is not legitimate. Presumably editor-admins aren’t choosing to engage in poor behavior in this instance.