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Hourly Extreme Rainfall Claims Not Supported By Data

March 3, 2021

By Paul Homewood

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This paper came out a couple of months ago, another one claiming to prove that global warming is leading to more extreme rainfall. It focusses on hourly rain data, and attempts to correlate this with dew point temperatures, a proxy of absolute humidity:

 

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https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL090317

 

The first question is why don’t they simply monitor the hourly rainfall trends themselves, instead of using dew points, which are not accurate anyway?

The study uses 7000 rain gauges spread around the world, but England is one area focussed on. On the map below, the orange and red circles indicate where hourly precipitation has increased in line with the  Clausius‐Clapeyron equation (6.5%/K):

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So according to the theory, Oxfordshire should be seeing much more extreme rainfall.

Hourly rainfall data is not readily available for most stations, nor is there much history. But the Met Office do have data for Benson, Oxfordshire back to 1975, available through their MIDAS system.

Each year is filed separately, so it is a bit of a ball aching task! But I have downloaded all of the data, and extracted the top 100 wettest hours (17.3mm and over):

 

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You don’t need any fancy statistical tools to work out that hourly rainfall has not been getting more extreme. The top three were:

August 1977

September 1992

September 1980

 

With 100 events over the 43 years, the average is 2.32 pa, The last ten years has seen 19 of these, which is of course below the average.

This is only one station, but if the theory is correct, it should be apparent at all stations, including Benson.

It should also be pointed out that the daily data leads us to the same conclusion:

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https://www.ecad.eu/indicesextremes/customquerytimeseriesplots.php

 

Regardless of the theories, I suspect what the actual data is telling us is that weather is always the dominant factor. By that I mean that rainfall is determined by the meteorological conditions, which are fundamentally random. Whatever effect climate change may or may not be having, it is miniscule and unmeasurable in comparison.

26 Comments
  1. March 3, 2021 4:22 pm

    Same “nothing-burger” observation in Canada – over 220 weather stations show no overall change in the extreme rainfall intensities (20-year, 50-year, and 100-year rainfall intensities have decreased on average overall when we factor in the last 10 years of data in the Engineering Climate Datasets): https://www.cityfloodmap.com/2020/07/how-have-rainfall-intensities-changed.html. This is despite higher annual precipitation in some regions. That may be explained by the higher 2-year intensities, meaning we are indeed seeing more small, drizzly events, adding up to more precip over the year (meaning more mushrooms growing on our lawns). But not more severe extreme rainfall, e.g., that is responsible for flooding. The typical theory is that when the means (2-year return periods) shift, so do the extremes (more wilder weather, bigger 100-year storms) – but the data shows that means and extremes are going in opposite directions. Always best to check theory with data 🙂

  2. 1saveenergy permalink
    March 3, 2021 4:22 pm

    Nice one Paul !

  3. GeoffB permalink
    March 3, 2021 4:34 pm

    For the second time this week……..Don’t confuse me with the facts, my mind is made up. It’s climate change.

    • March 3, 2021 5:19 pm

      Those facts are always getting in the way of the models. Which to believe?

      • Gerry, England permalink
        March 3, 2021 6:37 pm

        Models – obviously.

        If I had the time I would search for the quote for the leading alarmist who actually said models should be believed over factual data.

  4. March 3, 2021 5:48 pm

    I experienced a proper hour of rainfall when driving in Southern USA, it was so heavy that all traffic had to stop due to zero visibility, a miracle that no accidents occurred. Is an odd hour or two of heavy rain of any importance in Western Europe? Floods here are due to persistent rain for several days, on already wet ground or full rivers.

  5. Gary H permalink
    March 3, 2021 5:50 pm

    “Globally, hourly precipitation extremes have increased during recent decades and are projected to intensify more in the future.”

    Just ignore the ‘prediction.

    Every time I see the, ‘in recent decades’ bit, my immediate thought is well, Earth had a cooling for decades leading up to the 1970,’s and then warming since (similar to the earlier cycle of GW earlier in the 20th Century). . . so go back to your starting point and analyze the decades preceding that.

    • Mack permalink
      March 3, 2021 7:46 pm

      Good point Gary. The first half of the 20th Century has proven a real problem for alarmist zealots. The warming was as significant as the later two decades, and included, arguably, the hottest and driest years known to modern man (the ‘Dust Bowl’ years of the 1930s in the US being a prime example) interrupted by 3 decades of cooling that does not conform to global warming theory. Hence the ‘Adjustocene’, where there has been a concerted attempt by the Pharisees of Climate Data to eradicate the early 20th Century warming, and the later cooling, to produce an inexhorable warming trend. Complete nonsense of course, but the individuals who control the historical data unfortunately control the current doomster narrative. And muppets like our current ruling political class fall for it, hook line and sinker. There just following ‘the science’ don’t you know?

      • Gary H permalink
        March 3, 2021 8:45 pm

        Indeed Mack.

        “Adjustocene” – I like that!

  6. mjr permalink
    March 3, 2021 6:18 pm

    off topic but for info.
    Costing the Earth – R4 yesterday
    “How to Halve Emissions by 2030
    The COP26 conference in Glasgow in November is going to be a very important moment in tackling climate change. We are currently not on track to meet the goal of limiting global temperature rise to between 1.5 and 2 degrees above pre-industrial levels. According to the UN Intergovernmental Panel on Climate Change, we need to halve total emissions by the end of 2030 if we’re to be on track to hit the 1.5 degree target and avoid the worst effects of a changing climate. To close the gap between pledges and action, countries need to sign up to policies and strategies that start to reduce emissions now. This is the challenge for the summit in Glasgow.
    Tom Heap is joined in the studio by Nigel Topping, the High Level Climate Action Champion for COP26, to discuss the ambition of the summit and the momentum that is building not just among governments but cities, investors and businesses to deliver net zero by mid-century. They hear from three experts who will give us real world practical solutions to achieve far-reaching carbon cuts by 2030: Dr Rhian-Mari Thomas, Chief Exec of the Green Finance Institute; Dr Stephen Cornelius, Chief advisor on Climate Change at WWF UK; and Dr Angela Wilkinson, CEO of the World Energy Council. Can we really halve emissions by 2030?”

    This will be an impartial and objective discussion – NOT
    https://www.bbc.co.uk/programmes/m000sqlc

  7. Phoenix44 permalink
    March 3, 2021 6:19 pm

    I remain confused. Why did they use a measure of humidity rather than temperature? And how can you correlate an hourly thing with a daily thing? Isn’t that just nonsense?

    Once again a paper ignores what you could actually do on a detailed level in favour of looking at the entire globe on a proxy, assumed, adjusted basis. Yet the detailed work fails to support the global claims. Again. Weird eh?

    • Chris Morris permalink
      March 3, 2021 7:05 pm

      The wet bulb temperature, or the dew point, are the measures of how much water there is in the air. Dew point can be harder to measure so most weather stations just do wet bulb or nowadays relative humidity. There is no direct correlation between the dry bulb or “air” temperature and moisture except dry bulb is either the same or higher than wet bulb. The wet bulb is generally higher than dew point. That is why in temperate climates, there can be a lot of variability in dry bulb on a daily basis, but a lot less in the wet bulb. After dark, the dry temperature often drops rapidly until it gets to about wet bulb, these drop to about dew point and then they more slowly drop. Changing the heat content needs a lot more energy in or out than it does for the same mass of air. This is especially true if the water is vapour. Condensing it to water gives out a lot of heat.
      It is this moisture in the air that is the source of rain, so the higher the wet bulb, the heavier the rain could be. But it still has to rain. On many humid days, it doesn’t rain. That is where their theory goes wrong. Just because the conditions are there, doesn’t mean it will happen.

  8. Jack Broughton permalink
    March 3, 2021 6:30 pm

    The media climate hype seems to be increasing much faster than global warming. Almost every article, even the pensions section, of the eco-obsessed “i” today mentioned the climate emergency etc. They then made the claim that China was reducing its emissions: they meant improving its kg CO2 / GNP ratio, but did not understand that so just crowed.

    The brainwashing is now reaching a fever-pitch that Big Brother would be proud of, he’d call it bellyfeel prolefeed I guess.

    • Harry Passfield permalink
      March 3, 2021 7:54 pm

      The brainwashing is reaching fever pitch because the warmists know there’s a big cooling coming and they’ve got to make hay while the sun (don’t) shine. Not to mention more kids to propagandise.

  9. dpb permalink
    March 3, 2021 6:58 pm

    Average wind output today 0.503 GW!!!

    • Mack permalink
      March 3, 2021 9:55 pm

      Erm, not quite the Saudi Arabia of Wind, more like the Saudi Arabia of Democracy, i.e. bugger all! What could possibly go wrong Boris?

  10. March 3, 2021 7:17 pm

    Off topic, but for the record: this evening’s demand in UK is 42GW. Only 3.7% from renewables, of which wind is just 1.7% (hydro 2%). You won’t see those figures in the MSM timorrow!

    • March 3, 2021 8:17 pm

      Anticyclonic gloom: no wind, no solar, no hydro (run-of-river).

  11. Vic Hanby permalink
    March 3, 2021 7:35 pm

    I’ve refereed hundreds of journal papers and an obvious problem with this one is that the two parameters being compared are at different time scales. This is simply stated in section 2.1 with no justification. A quick analysis of hourly data for some UK locations shows that the absolute humidity does vary significantly over a day. The conclusions are weak and the authors don’t relate the results meaningfully to the local physical conditions.
    A lot of fuss for no real impact.

  12. Stonyground permalink
    March 4, 2021 8:32 am

    Apologies for being OT but have you seen this?

    https://extinctionclock.org/

    A handy resource for sceptics I thought.

  13. A C Osborn permalink
    March 4, 2021 10:11 am

    This says it all “Whatever effect climate change may or may not be having, it is miniscule and unmeasurable in comparison.”
    Especially when referring to temperatures, they are publicising 0.01C to 0.1C rises in temperature when we can see up to 40C change in 24 Hours and 80C change in 24 months in some parts of the world.
    We have adapted, it is what we are good at.

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