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Met Office Claim Of “Heavier Summer Downpours” Not Borne Out By Actual Data

February 23, 2018

By Paul Homewood




Back in 2014, the Met Office’s Lizzie Kendon jointly authored a paper, “Heavier summer downpours with climate change revealed by weather forecast resolution model”.

The Met Office reported:

June 2014 – A recent research paper which appeared in Nature Climate Change has looked at how summer rainfall may change in future with a changing climate. Here, the lead author of the paper, Dr Lizzie Kendon from the Met Office, gives some additional insight into some aspects of the research.

This research aimed to understand how hourly rainfall may change in future with global warming. This involved running a very high resolution model, similar to the one we use for forecasting, to look at summer rainfall patterns over a 13-year period both now and at 2100.
Clearly potential conditions around 2100 in the UK are subject to variables such as the amount of human greenhouse gas emissions emitted, so we have to make some assumptions. We chose to use the IPCC RCP8.5 scenario – which is their highest end scenario which would see the most warming.

Why did we choose the highest IPCC (RCP8.5) scenario?

In this study we are trying to understand how hourly rainfall may change in the future with global warming. We chose the highest scenario in order to allow us to identify any signal of change above natural climate variability. The fact that we used the highest scenario, however, doesn’t mean we cannot translate our findings to lower emission scenarios or to time periods earlier this century. What we have confidence in is the direction of the change – namely in an increase in heavy summer downpours in future. That direction of change is not expected to vary between high and low emissions scenarios. Further research in the future could help narrow down how much heavier rainfall is likely to be under different IPCC scenarios and give more detail overall, but – given how computer intensive the study was – this is likely to take some time.

Why does our study only consider the southern UK?

The high resolution climate model used in this study, needed to allow us to examine changes in short-duration intense storms, is very computationally expensive. Even running for just the southern half of the UK, it took the Met Office’s supercomputer – one of the most powerful in the world – nine months to complete the simulations.
The southern UK was chosen for this initial study as convective storms, which are responsible for delivering intense summer downpours, are more common in that area. In addition we are interested in examining urban effects, and London is the largest urban area in the UK – so it made sense to include it in the study area. Similar climate change simulations for the northern half of the UK are currently being set up, and will be examined in a future study.

How robust are these results?

These results are based on one climate model and so we cannot assess modelling uncertainties. Although this model shows almost five times more events exceeding high thresholds indicative of serious flash flooding, we need to do more research before we can be confident of this figure. We have more confidence in the direction of the change – with increases in the intensity of heavy rain consistent with what we expect theoretically as the world warms. We need to wait for other centres to run similarly detailed simulations to see whether their results support these findings.


As Lizzie Kendon makes clear in the video (in the above report), summer downpours will become heavier in the future, according to her models.

She is looking specifically at hourly rainfall. As there is very little such data available, it is impossible to test the model retrospectively.

However, we can look at daily and monthly extremes. It is not unreasonable to assume that heavier downpours, of the sort modelled, would also translate into more extreme daily data.

In any event, as her paper begins:

The intensification of precipitation extremes with climate change1 is of key importance to society as a result of the large impact through flooding. Observations show that heavy rainfall is increasing on daily timescales in many regions.

it would seem sensible to look at daily extremes, which are likely to have a much greater impact on flooding than hourly ones.


Although Kendon specifically looked at southern England, let’s start by looking at the England & Wales series as a whole:



The standout was ex Hurricane Charlie in August 1986, which brought deaths and wide spread flooding to both Ireland and Britain, and must be dismissed as a one off.

Either way it is abundantly clear that daily rainfall is not becoming more extreme.


Looking at the whole of England and Wales, of course, can be a bit misleading, as a high total may simply reflect a small amount spread over the whole country.

Equally, an extreme downpour over a small area would not be seen in the overall average.

So let’s also look at the South East, a much smaller area:


Region definitions for EWP



Again, we find no evidence of rainfall becoming heavier. There appears to be a period in the 1990s and early 2000s when extreme daily rainfall lessened. But over the full period, there seems to be little pattern.


Finally we can look at daily rainfall at Oxford, which is just about as central you can get in southern England:



Again there is no discernable pattern.

Of course, you would need to look at hundreds of “Oxfords” to get a fair picture of what are essentially local events.

Nevertheless, from the three sets of data shown above, there is no evidence that heavier summer downpours have been occurring since 1931, despite temperatures rising.

England Mean temperature - Summer


That does not necessarily invalidate the modelled projections for 2100, when Lizzie and the rest of us will all be dead. But it does strongly suggest that they cannot be relied on.

  1. February 23, 2018 7:24 pm

    The only thing reliable about any of the climate models is that they are based on assumptions and not science and that they have not been validated. GIGO applies to climate models in spades.

    • Tom O permalink
      February 23, 2018 7:33 pm

      Basically, they are not “models” at all, since you have to know what you are modeling in order to model it. They are expensive climate versions of Sim City or Sim Farm or, in their case Sim Weather. There is a vague similarity between their output and what they are attempting to simulate, just like there is a vague similarity to the board game Risk and world conquest.

  2. February 23, 2018 7:35 pm

    Not to mention starting point RCP8.5 is impossible from first principles. BAU comparable to AR4 A2 or A1B is intermediate between RCP4 and RCP6.

    • Jack Broughton permalink
      February 24, 2018 10:30 am

      If the hypothetical radiative feedback mechanism was correct and the hypothetical radiative forcing factor was really increasing then all is possible: good that neither can be proven, measured or tested other than in computer games as Tom O says. The GIGO comment is also basic to this paper. Once the statement that the “science is proven” is accepted anything is possible!

  3. quaesoveritas permalink
    February 23, 2018 7:50 pm

    In June 2014, I sent two emails to Ms Kendon, to which I received no reply.

    First email (June 1st):

    “Re: Heavier summer downpours with climate change revealed by weather forecast resolution model

    Given that observed temperatures have so far been at the lower end of IPCC climate model predictions, why do you think it is valid to use the most high-end climate projections from the Intergovernmental Panel on Climate Change for this study? Would it not have been sensible to use the most accurate predictions of temperature, i.e. the “commitment” scenario which assumes zero increase in CO2. Or would that not have been sufficiently alarmist?”

    Second email (June 11th):

    “Re: Heavier summer downpours with climate change revealed by weather forecast resolution model

    I am writing to you again as I have not had a reply to my first e-mail. Regarding this research, I would be grateful to know why you used “the most high-end climate projections from the Intergovernmental Panel on Climate Change” for the study, instead of more realistic projections such as those from the “commitment” scenario, which are the only ones which have proved accurate to date? Also you state that “This model gives a realistic representation of hourly rainfall, allowing us to make future projections with some confidence.” However, in my experience the Met. Office rainfall 5 day forecasts for the UK are very poor at forecasting the location and timing of heavy rainfall events. ”

    However, I am sure that the UKMO would argue that the study extended to the end of the century, and 4 years is too short a time to come to any conclusions regarding it’s accuracy.
    As you say, we will all be dead long before we know how accurate the predictions were.

  4. Stuart Brown permalink
    February 23, 2018 8:03 pm

    “Either way it is abundantly clear that daily rainfall is becoming more extreme.”

    Did you mean to say that, Paul? I suspect not from the graph and context 🙂

    • diogenese2 permalink
      February 24, 2018 10:02 am

      I thought he had omitted the “sarc” tab.

      • quaesoveritas permalink
        February 24, 2018 12:45 pm

        Always a dangerous thing to do.

  5. CheshireRed permalink
    February 23, 2018 8:42 pm

    Essentially these ‘studies’ are designed to generate lurid media headlines and send a message of impending catastrophe to whichever government minister holds the purse strings. Or to summarise; ‘send more money’.

  6. February 23, 2018 9:47 pm

    Clearly potential conditions around 2100 in the UK are subject to variables

    Which is why the Met Office has no chance whatever of making any useful predictions 80+ years ahead. Why don’t they just give it up and quit pretending to have skills they can’t possibly have?

    • quaesoveritas permalink
      February 24, 2018 12:44 pm

      Because they are probably being paid a generous salary for doing it.
      It’s relatively easy work.

  7. February 23, 2018 10:13 pm

    Mann on radio nz

  8. February 23, 2018 10:54 pm

    All a waste of time.

    The atmospheric Rankine Cycles pumps around 680 WattHrs/sq.m up into the atmosphere for every Kilogram of water evaporated which returns as rain etc. It accelerates when the heat is turned up to offset temperature rise.
    Calculation roughly based on IPCC figures show that for a 3.34 Watts/sq.m of Radiative Forcing the global increase in rainfall would increase by a mere 0.034%. Gets lost in the noise.
    So why are we mucking about with statistical weather patterns in a chaotic system?

    • February 24, 2018 6:26 am

      Because “we” are being handsomely rewarded by the taxpayer for doing something useless and worthless.

  9. Silver Dynamite permalink
    February 24, 2018 8:28 am

    The Soviet Union had a Department of Agitation and Propaganda which was the model for what has been termed AgitProp. The Russian Government uses Twitter Trolls to perpetuate its unending paranoia and inferiority about the ‘West’.
    Second rate climate scientists use the same tactics to pursue their quest for publicity and money. The MetOffice and their ilk have become useful idiots.

  10. diogenese2 permalink
    February 24, 2018 8:47 am

    “Even running for just the southern half of the UK, it took the Met Office’s supercomputer – one of the most powerful in the world – nine months to complete the simulations.”

    of course, the programme needs to be run a couple more times to check.

    We can wait…..

  11. Bitter@twisted permalink
    February 24, 2018 9:18 am

    Methinks that Lizzie should get off her backside, walk over to the window and actually do some real-world observations.
    After all she does work for the Met Orifice.

  12. Wellers permalink
    February 24, 2018 9:37 am

    Paul – I think you omitted the word not…

    Either way it is abundantly clear that daily rainfall is NOT becoming more extreme.

  13. Phoenix44 permalink
    February 24, 2018 10:20 am

    How do intelligent people get sucked in by models? Just making a model really big and complex, and having it run for months means nothing except the answer will be wrong. If you “need” a big model that means you have something you cannot model accurately because you cannot get right either the starting conditions or the huge number of assumptions a complicated model requires.

    Far better to pare you model down what you do know and run scenarios. But then of course that would show that we don’t really know what is going to happen.

    • Smoke_and_mirrors permalink
      February 24, 2018 11:36 am

      Spot on!
      If you can’t find the answer or even a trend with a simple approximation time and time again then, sure as eggs, you’ll never get any closer with a complex model.
      Scrap the lot and start again!

  14. Ben Vorlich permalink
    February 24, 2018 11:59 am

    Did Ms Kendon get the additional funding she was trying so desperately to get? Possibly as she’s still modelling at the MO.

  15. February 25, 2018 9:11 pm

    I know a thing or two about modeling electronic systems which are well characterised and relatively simple compared to the climate. It takes awhile to iron out the bugs there will be some and we never have complete confidence until we have real hardware to test.
    How the fuck do you run a simulation for 9 months expecting the model to be bug free? Definition of academia cloud cockoo land.

    • catweazle666 permalink
      February 25, 2018 9:44 pm

      “How the fuck do you run a simulation for 9 months expecting the model to be bug free?”

      Especially of an effectively infinitely large open-ended non-linear feedback-driven (where we don’t know all the feedbacks, and even the ones we do know, we are unsure of the signs of some critical ones) chaotic system – hence subject to inter alia extreme sensitivity to initial conditions, strange attractors and bifurcation…

      Nice work if you can get it.

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