Climate Scientists Confirm No Global Increase in Extreme Weather Events

It’s now accepted in certain quarters that climate change AKA anthropogenic global warming (AGW) is causing more frequent extreme weather events, and about once a week along comes another extreme event that gets blamed on AGW,  with the most recent being the Chilean floods. Before that we had the California drought, Cyclone Pam, the frigid US winter, the Boston blizzard and the Australian bushfires. We can in fact trace a chain of extreme events allegedly caused in whole or in part by AGW that goes all the way back to hurricane Katrina in 2005, the “superstorm” that got the ball rolling.

Now, however, a report that calls these claims into question has come to Energy Matters’ attention. We are not presently at liberty to disclose which report it is, but it’s written by a group of climate scientists whose academic credentials are impeccable and who have numerous peer-reviewed publications to their credit. The report concludes that with the arguable exception of heat waves there is no compelling observational evidence for global increases in the frequency of any extreme weather events, meaning that the oft-heard claims that AGW is causing more of them are totally without foundation.

Here is a brief summary of what the report says.

We begin with Heat Waves. A global increase in heat waves would be a logical expectation because mean global surface air temperatures have risen. But because of conflicting trends in different regions and other uncertainties (such as how to define a heat wave) the report has only “medium confidence” that there has been such an increase.

(T)here has been a likely increasing trend in the frequency of heatwaves since the middle of the 20th century in Europe and Australia and across much of Asia where there are sufficient data. However confidence on a global scale is medium due to lack of studies over Africa and South America but also in part due to differences in trends depending on how heatwaves are defined. There is also evidence in some regions that periods prior to the 1950s had more heatwaves (e.g., over the USA, the decade of the 1930s stands out) while conversely in other regions heatwave trends may have been underestimated due to poor quality and/or consistency of data.

This combined with issues with defining events, leads to the assessment that there is medium confidence that globally the length and frequency of warm spells, including heat waves, has increased since the middle of the 20th century.

Next Extreme Precipitation. Because of conflicting results, lack of data and more definitional uncertainties (in this case how to define “extreme”) the report is unable to reach a firm conclusion as to whether extreme precipitation events are on the rise globally or not:

Given the diverse climates across the globe it has been difficult to provide a universally valid definition of ‘extreme precipitation’. In general, statistical tests indicate (that) changes in precipitation extremes are consistent with a wetter climate, although with a less spatially coherent pattern of change than temperature, in that there are large areas that show increasing trends and large areas that show decreasing trends and a lower level of statistical significance than for temperature change.

In summary …. it is likely that since 1951 there have been statistically significant increases in the number of heavy precipitation events (e.g., above the 95th percentile) in more regions than there have been statistically significant decreases, but there are strong regional and subregional variations in the trends.

On to Floods. The report finds no “clear and widespread” evidence for a global trend. In fact it can’t even define the sign of the global trend, if there is one, with any confidence:

While the most evident flood trends appear to be in northern high latitudes, where observed warming trends have been largest, in some regions no evidence of a trend in extreme flooding has been found, e.g., over Russia. Other studies for Europe and Asia show evidence for upward, downward or no trend in the magnitude and frequency of floods, so that there is currently no clear and widespread evidence for observed changes in flooding except for the earlier spring flow in snow dominated regions.

In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale.

Likewise Droughts. For much the same reasons the report also can’t identify a global trend in droughts with better than low confidence, and again it doesn’t say whether the trend is up or down.

Because drought is a complex variable and can at best be incompletely represented by commonly used drought indices, discrepancies in the interpretation of changes can result. For example, Sheffield and Wood found decreasing trends in the duration, intensity and severity of drought globally. Conversely, Dai found a general global increase in drought, although with substantial regional variation and individual events dominating trend signatures in some regions. Studies subsequent to these continue to provide somewhat different conclusions on trends in global droughts and/or dryness since the middle of the 20th century.

In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century, due to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice.

Next Severe Local Weather Events. The report reaches effectively the same conclusion as it reaches for floods and droughts:

(S)evere local weather phenomena (include) hail or thunderstorms. These are not well observed in many parts of the world, since the density of surface meteorological observing stations is too coarse to measure all such events. Moreover, homogeneity of existing reporting is questionable. Alternatively, measures of severe thunderstorms or hailstorms can be derived by assessing the environmental conditions that are favourable for their formation but this method is very uncertain.

In summary, there is low confidence in observed trends in small-scale severe weather phenomena such as hail and thunderstorms because of historical data inhomogeneities and inadequacies in monitoring systems.

Next Tropical Storms: For once the report is unequivocal. There are no global trends:

Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century and it remains uncertain whether any reported long-term increases in tropical cyclone frequency are robust, after accounting for past changes in observing capabilities. No robust trends in annual numbers of tropical storms, hurricanes and major hurricanes counts have been identified over the past 100 years in the North Atlantic basin.

Finally Extratropical Storms. The assessment concludes with more accounts of conflicting and/or ambiguous results and votes of low confidence:

Studies that have examined trends in wind extremes from observations or regional reanalysis products tend to point to declining trends in extremes in mid-latitudes and increasing trends in high latitudes. Other studies have compared the trends from observations with reanalysis data and reported differing or even opposite trends in the reanalysis products. On the other hand, declining trends reported over China between 1969 and 2000 were generally consistent with trends in NCEP reanalysis. Trends extracted from reanalysis products must be treated with caution however.

In summary, confidence in large scale changes in the intensity of extreme extratropical cyclones since 1900 is low. There is also low confidence for a clear trend in storminess proxies over the last century due to inconsistencies between studies or lack of long-term data in some parts of the world (particularly in the SH). Likewise, confidence in trends in extreme winds is low, due to quality and consistency issues with analysed data.

So there it is. Except maybe for heat waves the available data provide no good evidence for global increases (or decreases) in any extreme weather events over the period of observational record. Barack Obama, John Kerry, Ban Ki-moon, the US National Climatic Data Center, the UK Met Office, Al Gore, Nature magazine and many others, please take note.

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24 Responses to Climate Scientists Confirm No Global Increase in Extreme Weather Events

  1. Willem Post says:


    The US Southwest is having a rather long-term drought which has dried the soil.

    During the 20s and 30s, a similar drought affected the Midwest, with dust storms, people abandoning their farms, banks holding worthless mortgages; quantitative easing had not yet been invented.

    All those attending the upcoming GW meeting in Paris should have a copy of the report to prevent a stampete of ill-considered “GW-fighting” plans.

    • The attendees at the Paris meeting are not interested in the science. if they were they would not be meeting. They are interested in the loot, the more loot the better so they can level the playing field where all us westerners are sinners and trampling on the poor innocents of the third world or so the IPCC head folks say even the one booted for his sexual appetites.

    • mbe11 says:

      All they want is the loot, science is not the concern of the looters in Paris.

  2. mbe11 says:

    When you quote something the withholding of the source is usually an indication the source is horse manure. I suggest providing the source if you want to state something based on somebodies else work. You could quote in the 2014 intra insurance industry report which had pay outs due to weather down from average. That is real money and real results with no low confidence or medium confidence or high confidence applying.

  3. Jamie says:

    mbe11 Roger is being silly. If you Google the text you’ll see it’s from the ipcc. Of course Roger doesn’t mention that it’s inherently extremely difficult to detect statistically significant trends in extreme events because they are, by definition, rare events so the trends take a long time to emerge.

  4. Hugh Sharman says:

    Jane Francis on “Life Scientific” yesterday was, I thought interesting and worth listening to if you have the odd half hour

    Similarly, I enjoyed “Costing the Earth” at which dealt with the arguments of us, of a more sceptical viewpoint

  5. Gavin Doyle says:

    Like so many things weather related, a heat-wave is a subjective phenomenon. And as the population increases (the one statistic we know for absolute sure), there will logically be more subjective accounts of “waves” of heat…. or floods and Earthquakes becoming more destructive. People have an innate desire to tell their mates that they’ve experienced something unusual. Usually they’re lying.

  6. Roger,

    I don’t think IPCC is particularly useful in this context, it is ultra-conservative report, but on the other hand, still consensual on many aspects of climate system. Regarding their report on weather/climate extremes, it is unnecessary conservative (as e.g. with Arctic ice decline), which I think is partly the result of a work of certain group of people. But anyway, I would point you to another report from Munich Re, who have money in the weather/climate extremes, and money speaks louder (as they always do):

    For me the most convincing piece of evidence that global warming has been contributing already to more and more intense weather related natural catastrophes is the fact that while we find a steep increase in the number of loss relevant weather events (about tripling in the last 30 years) we only find a slight increase in geophysical (earthquake, volcano, tsunami) events .

    Now, that is quite a statement, isn’t it? Here is the source from alarmist’s website Climate Progress
    Global Warming Linked To More Extreme Weather And Weaker Jet Stream


    • A C Osborn says:

      Alex, would you please list those weather events that are increasing so that we can check them against actual data?
      The cost of any kind of claim is increasing because there are more people, more houses with more “stuff” in them to be ruined and in no way reflects the actual weather events themselves.
      We already know that there have been decreases in
      Hurricanes & Typhoons making land fall.
      Tornadoes in the USA.
      Wild Fires in the USA and Australia
      Droughts and their intensity, especially when related to Population growth and lack of the required Water management.
      Floods, especially when related to Population growth and lack of maintenance or improvements in flood defenses.

      • A C Osborn says:

        I forgot to include that Wild Fires have decreased despite changes in policy due to “Green” intervention making the fire “stock” worse than it used to be when it’s reduction was practised.
        Plus a reduction in Super Tanker Aircraft to fight the fires as well.

        If you actually believe that the current California “Drought” bears any resemblance to the droughts of the 1930s I suggest you aquaint yourself to the Palmer drought index.
        The 2012 drought was far worse than the current California drought which has been caused just as much by a far larger population, growth in Farming and very poor water management as it to lack of rain and snowfall.

      • The cost of any kind of claim is increasing because there are more people, more houses with more “stuff” in them to be ruined and in no way reflects the actual weather events themselves.

        Are you joking? If you really think I am that stupid that I dont know that there is more people in this planet, don’t waste your time with me. I will not waste my time with you, as well.


        • A C Osborn says:

          You are absolutley correct Alec, there is no point in trying to have a debate with you.
          You use a typical response of picking a single comment that you can take issue with, even though it was factual and use it to NOT respond to all the actual questions or counter points that I have made.
          So like you I will no longer bother to respond to your comments. for the people in the UK “and it is goodbye from him”.

    • Roger Andrews says:


      The other day I presented you with some GHCN rainfall data that contradicted claims of drought in Brazil. You told me you would rather believe the conclusions of a respected scientist who had a number of peer-reviewed publications to his credit.

      Now I present you with the conclusions of a large number of respected scientists who have literally thousands of peer-reviewed publications to their credit and you tell me you would rather believe the claims of an insurance company.

      Sorry, but you can’t have it both ways 😉

      • Roger,

        I thought you only “contradicted” the connection between the deforestation and increasing drought. (by making correlations between average precipitation over whole countries and forest cover over whole countries). Because saying there is no (significant) drought, while people are starting to fight over water is not even 1st April fool’s joke.

        As for citing the IPCC’s report that there is only relatively safe confidence on the link between warming and heat waves, while large uncertainity on other extremes, is fine. I don’t see a single convincing reason, why a higher energy world would NOT lead to an extreme(er) word one way or another. Energy has to go somewhere, and that “somewhere” is also more extreme weather.

        Mind you, I don’t have to swallow everything IPCC says, since is only says most sure of sure things on Earth, just not to “upset” sceptics.

        And not to forget, carbon emission would be an immense problem even in that case, they would ONLY affect ocean’s pH and would have NO radiative effect on the atmosphere, since I don’t think it’s sustainable to wipe out ocean’s life sooner or later.



    • Tom Moran says:

      There is no evidence to support a weaker jet stream or the fallacy that global warming causes extreme weather. Even these warmist scientists concede that a warmer earth means less extreme weather….

    • roberto says:

      No kidding!…. an insurance company that raises the spectre of an increase of weather-related damages… just to increase the premiums paid by those it insures?

      Wake up!


    • roberto says:

      For the record… about weather-related payments by Munich Re:

      Do you see a clear trend upwards? I can’t see it… I see only random fluctuations.


  7. fspano says:

    Helo Euarn, when is the report going to be available? Only with a paper to check one can learn the findings and make an informed judgement.

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