US Instrumental Records Indicate More Heat Waves Occurred In the 1930s Than Today

During the 1930s, when the atmospheric CO2 concentration was about 100 ppm lower than today (310 ppm vs. 410 ppm), United States heat waves were just as if not more common than recent decades.

Recently there has been much ado about heat waves and the hottest-ever-recorded-temperatures making their rounds in Northern Hemisphere summer.

Yet scientists have determined that heat waves are largely driven by natural variability, not anthropogenic CO2 emissions.

Dole et al., 2011

Was there a basis for anticipating

the 2010 Russian heat wave?

The 2010 summer heat wave in western Russia was extraordinary, with the region experiencing the warmest July since at least 1880 and numerous locations setting all‐time maximum temperature records. This study explores whether early warning could have been provided through knowledge of natural and human‐caused climate forcings.
“The July surface temperatures for the region impacted by the 2010 Russian heat wave shows no significant warming trend over the prior 130‐year period from 1880 to 2009. A linear trend calculation yields a total temperature change over the 130 years of −0.1oC.”
“Model simulations and observational data are used to determine the impact of observed sea surface temperatures (SSTs), sea ice conditions and greenhouse gas concentrations. Analysis of forced model simulations indicates that neither human influences nor other slowly evolving ocean boundary conditions contributed substantially to the magnitude of this heat wave. They also provide evidence that such an intense event could be produced through natural variability alone. Analysis of observations indicate that this heat wave was mainly due to internal atmospheric dynamical processes that produced and maintained a strong and long‐lived blocking event, and that similar atmospheric patterns have occurred with prior heat waves in this region. We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability. Slowly varying boundary conditions that could have provided predictability and the potential for early warning did not appear to play an appreciable role in this event.”

Shiogama et al., 2013

Attribution of the June–July 2013 Heat

Wave in the Southwestern United States

A severe heat wave occurred in the southwestern United States (US) during June and July 2013. To investigate the effects of natural variability and anthropogenic climate change on this event, we generated large ensemble simulations of possible weather using the MIROC5A climate model forced by “historical external forcing agents, sea surface temperature (SST) observations and sea ice (SIC) observations” both with and without human influence. It was suggested that both the anthropogenic warming and an atmospheric circulation regime related to the natural variability of SST and SIC made the heat wave event more likely. On the other hand, no significant human influence was found in atmospheric circulation patterns. These results were robust for two different estimates of anthropogenic signals on SST and SIC.”

These conclusions are consistent with the observation that heat wave events have not been increasing in tandem with the dramatic rise in CO2 emissions over the last century, further rendering the link between human activity and heat waves dubious.

In the United States, for example, where the most extensive long-term instrumental temperature data reside, there has been no significant trends in heat wave frequency since the 1880s, and there has been an overall decline in the number of decadal-scale heat waves since the 1930s.

Peterson et al., 2013

Monitoring and understanding changes in

heat waves, cold waves … in the United States

For the conterminous United States, the highest number of heat waves occurred in the 1930s, with the fewest in the 1960s. The 2001–10 decade was the second highest but well below the 1930s. Regionally, the western regions (including Alaska) had their highest number of heat waves in the 2000s, while the 1930s were dominant in the rest of the country.”
Image Source: (Peterson et al., 2013)

Ruprich-Robert et al., 2018

Impacts of the Atlantic Multidecadal Variability on

North American Summer Climate and Heat Waves

Heat waves are primarily driven by internal atmospheric variability (Schubert et al. 2011, Dole et al. 2011), but their frequency of occurrence and severity can be modulated by atmospheric boundary forcing. Soil moisture deficits have been shown to play an important role in intensifying heat wave severity (Huang and Van den Dool 1993, Fischer et al. 2007, Jia et al. 2016, Donat et al. 2016).”
“Radiative forcing variations, such as those driven by anthropogenic emissions, can also modulate the occurrence of heat waves (e.g., Hansen et al. 2012). Previous studies, based on Coupled Global Climate Models (CGCMs) integrated under different anthropogenic forcing scenarios, concluded that over the US, the number of heat waves would increase during the 21st century (Meehl and Tebaldi 2004, Diffenbough et al. 2005, Lau and Nath 2012). However, this increasing trend may be modulated by the impacts on land of low frequency sea surface temperature (SST) variability (e.g., Schubert et al. 2016, Seager and Ting 2017), such as that associated with the internally-driven component of the Pacific Decadal Oscillation (PDO; Newman et al. 2016) or the Atlantic Multidecadal Variability (AMV; Schlesinger and Ramankutty 1994, Knight et al. 2005). These low frequency SST variations may explain why there has not been any long-term trend of heat waves detected over the US during the 20th century, despite the increase of radiative forcing (Kunkel et al. 1999, Easterling et al. 2000).”

Depietri and McPhearson, 2018

Changing urban risk: 140 years of

climatic hazards in New York City

“The trends based on the NOAA meteorological data show that changes in the length of the heat wave events equal or beyond 3 days of duration are not significant. The mean maximum temperature of the heat wave is also close to stable over the 140-year period of study with no significant increase. … Results obtained from the in-depth analysis of the NYT articles, corresponding to the dates of longer lasting heat wave events (i.e., equal or more than 6 days in duration), show that the number of deaths and people affected in New York City significantly declined. … The change in coping strategies mentioned in the newspapers articles and divided before and after the 1960s illustrates how the advent of air conditioning can be most likely contributed to the significant reduction in mortality due to extreme heat. … Also not significant are the trends in extreme precipitation (beyond 1.75 in. and beyond 3.5 in.) with significant inter-annual and interdecadal variability.”

Images Source: Depietri and McPhearson, 2018

28 responses to “US Instrumental Records Indicate More Heat Waves Occurred In the 1930s Than Today”

  1. Bob Koss

    Here is a graph of the heatwave index for the US. Nothing is close to the 1930s.

  2. Science studies say heatwaves were more common in USA during the 1930’s | Watts Up With That?

    […] Full story at No Tricks Zone […]

  3. SebastianH

    Yet scientists have determined that heat waves are largely driven by natural variability, not anthropogenic CO2 emissions.

    Why would the occurrence of a heat wave in a certain region be driven by CO2 emissions? Why do you think that this is what climate science or AGW proponents are saying?

    1. spike55

      Agreed, no heat wave is ever driven by CO2.

      There is no reason to imagine any CO2 warming at all, anywhere, anytime.

      .. Unless you are heavily into science fantasy like seb is.

    2. sunsettommy

      CO2 level and heat waves in the 1930’s is BEFORE 1950, therefore mostly natural.

      Can you figure out why 1950 is the dividing line?

    3. M E

      Because that is what the News Media tell us.
      I see that you don’t listen watch or read the news in either Hemispheres.

      1. Yonason

        “…that is what the News Media tell us.” – M E

        But where does the news media get that from, M E?

        “CO2: The Thermostat that Controls Earth’s Temperature”

        So, why would an activist want to distance himself from the very nonsense that underpins the whole warming scam? Why does he tell us these “scientists” know what they are talking about, but not want to be associated with the “science” he claims we don’t understand? On the one hand he tells us to believe them, and on the other that he doesn’t. It makes no sense. But then, making sense isn’t a very high priority with warmist activists, is it?

        1. SebastianH

          Dear Yonason,

          what is so difficult to understand when I write that CO2 isn’t causing a particular heatwave in a particular region? That’s not how it works and (I hope) is not what the news/media is telling U.S. citizens is happening.

        2. Yonason


          What is so difficult for the activists to understand about a lying pseudo-scientist shill for AGW using a heat wave to sell his faulty merchandise?

          “The US experienced a severe heatwave and drought during the summer of 1988, the Mississippi River nearly dried up, one-third of Yellowstone Park burned up, and it was the perfect time for James Hansen to start the global warming scam. He told Congress that he was 99% certain the heatwave was due to CO2, and that heatwaves would get much worse starting in the 1990’s.

          Not saying CO2 causing a PARTICULAR heat wave, but saying that ALL heat waves are made worse by CO2 is a distinction without a difference.

          It’s not just the MSM and the activists, but the climate “scientists” who feed them their “news,” who want us to think that CO2 is responsible. Then they tell us they didn’t mean it, and that they have no clue where we could have gotten such a stupid idea.


          The collective dishonesty of warmists knows no bounds.

          1. Yonason

            On a closely related note…

            Richard Lindzen says (as reported by Judith Curry) that…

            “…denial of the facts on the left, has made the public presentation of the science by those promoting alarm much easier. They merely have to defend the trivially true points on the left; declare that it is only a matter of well- known physics; and relegate the real basis for alarm to a peripheral footnote – even as they slyly acknowledge that this basis is subject to great uncertainty.

            Most readers here will immediately recognize that as a technique often employed by SebH in his persistent and feeble attempts at obfuscation.

    4. Newminster

      But it’s what we are being asked to believe, Seb.
      If we don’t cut our CO2 emissions we will get runaway global warming, according to “scientists” just today.
      And day in, day out we are told this or that heatwave “is what we must expect …” or “has been made more severe by …”
      Yet we find 1930s heatwaves every bit as severe as today’s.
      You’re right, Seb, why would the occurrence of a heat wave … be driven by CO2 emissions?
      But, at least by implication, that is what we are being told, isn’t it?

    5. SebastianH

      Because that is what the News Media tell us. […] But it’s what we are being asked to believe

      I see. So you don’t think that listening to what climate scientists say is better? Instead you cherry pick the few instances where “scientists” say that everything is alright and nothing changed from back then?

      why would the occurrence of a heat wave … be driven by CO2 emissions?

      Yes, why would it be? CO2 also doesn’t let it rain and doesn’t warm the surface (the typical skeptic nonsense argument: “how can cold CO2 warm the warmer surface?”). It’s important to understand the mechanisms involved.

      But, at least by implication, that is what we are being told, isn’t it?

      What scientists tell us is that more CO2 will cause more warming in the form of a higher heat content (among other things). How that heat gets distributed is another story and not what CO2 is causing. Is that too hard to understand?

      A higher heat content implies generally higher surface temperatures and thus more heat waves. But could also result in just warmer winters or warmer nights. That’s where the science isn’t settled … or at least it doesn’t look settled to me. When it comes to the physics of CO2, it’s pretty much settled … not matter how often you guys scream at the experts that it’s not and present weird arguments to support your beliefs 😉

      1. Newminster

        I understand the mechanisms involved, Seb, but I’m not sure you do.The physics of CO2 is pretty well settled. It does not influence temperature. Variations in atmospheric CO2 lag variations in temperature by anything up to 800 years. If anything temperature dictates CO2 levels.
        You have not provided any evidence (but then you don’t do evidence, do you) that this warm summer is anything other than an unusually warm summer any more than the cold winter in eastern Europe was anything other than an unusually cold winter.
        CO2 has nothing to do with either of those things and there is nothing any of us can do about either except turn up the aircon/central heating as appropriate!

      2. spike55

        “It’s important to understand the mechanisms involved.”

        Ah, seb’s MYTHICAL MECHANISM…

        That he can’t explain with any back-up from empirical science. His little fantasy fairy-tale.

        Poor seb.

        ZERO EVIDENCE of CO2 effecting climate.. anywhere, anytime, anyhow

      3. spike55

        “When it comes to the physics of CO2, it’s pretty much settled …”

        Yep, there is NO scientifically supportable, measured, physical mechanism by which CO2 can cause warming in out atmosphere.

        We are well aware of that.

        1. Yonason

          Always the same with him, isn’t it spike.

          “SebastianH 2. February 2018 at 8:36 AM | Permalink

          If only you guys would be able to properly look at anything instead of only re-enforcing what you already are convinced to be the truth.”

          My response to him then still stands along with spike’s and Kenneth’s and many others’, as unanswered now as it was then and before.

          “yonason (from my cell phone) 5. February 2018 at 9:45 AM | Permalink

          We’ll be happy to consider anything that the data support.

          So the ball is in your court. SHOW US THE DATA!

          I.e., PUT UP, OR SHUT UP!”

          He tells us to look at something else, but won’t tell us what that is, other than the incoherent nonsense he spews. So sad. Such a waste.

      4. spike55

        “present … arguments to support your beliefs”

        Something you have been TOTALLY UNABLE TO DO.

        Whenever asked to PRESENT THE EVIDENCE, you flap around like a headless chook.

        Let’s see this measured, empirical science to back up your “belief” in the mythical warming properties of enhanced atmospheric CO2.

        We have been waiting a LONG, LONG time.

        PUT UP, or stop your mindless attention-seeking TROLLING

    6. SebastianH

      Oh, and about climate change and heatwaves:

      So, it’s great that you guys look at the U.S. only (2% of the Earth’s surface?) and conclude that heat waves were hot in the past too …

  4. Science studies say heatwaves were more common in USA during the 1930’s – Climate Collections

    […] Posted on August 6, 2018 by Hifast From WUWT: Anthony Watts / August 6, 2018 Original story from No Tricks Zone […]

  5. tom0mason

    Weather is variable, during a cold period more so —

    Of note is that in year 1666 there was a months heatwave/drought that affected most of Europe. At that time in England, London had lain under an exceptional drought since November 1665, and the wooden buildings were tinder-dry after the long hot summer of 1666. After such an unusually hot and dry spring, temperatures in the summer of 1666 rose l.5°C above normal (estimated), and a precipitation shortfall of 6 inches turned London’s mostly wooden dwellings into large tinderboxes. The same conditions prevailed in much of northwestern Europe, giving rise to fires in a score of German cities. However the diary writing of Samuel Pepys and others who survived the confligration, such as the child Daniel Defoe (he would later write about the plagues and diseases of that time, and a first hand account of the ‘Great Storm’ of 1703), ensured the spectacular destruction of London were well documented, and it’s infamy was not overshadowed other urban fires elsewhere at the time.

    London however was not the only capital city where unusual drought in the mid seventeenth century produced a ‘Great Fire’ —

    Moscow in 1648, after several months without rain, ‘within a few hours more than half the city inside the White Wall, and about half the city outside the wall, went up in flames’.

    Large part of the new Mughal capital Shahjahanabad, now Delhi, burnt down after a prolonged drought in 1662.

    Istanbul suffered more (and more devastating fires) in the seventeenth century than in any other period of its history: one in 1660, once again after a prolonged drought, burned down 280,000 houses and several public buildings.

    Major blazes also regularly devastated Edo, the largest city in Japan, notably the Meireki fire of 1657 – which, like those in Moscow in 1648, Istanbul in 1660, Shahjahanabad in 1662, and London in 1666, broke out after an abnormal drought

    [Source: and
    and Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century. Geoffrey Parker.]

    All these happened during the LIA.
    And yes by December 1666, London like much of Europe was in the grip of a very cold winter, with severe frosts and ice over many European rivers including much of London’s Thames.

    1. Yonason

      LOL – tom0, harshing the warmunista narrative fact by inconvenient fact.

      Love it!

  6. M E

    Because that is what the NewsMedia tell us.
    I take it you do not derive your information from the news. They are available on the internet.In both hemispheres .

  7. US Instrumental Records Indicate More Heat Waves Occurred In the 1930s Than Today | Un hobby...

    […] by K. Richard, August 6, 2018 in NoTricksZone […]

  8. Weekly Climate and Energy News Roundup #325 | Watts Up With That?

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