Record Breaking Rain Claims Don’t Stand Up To Scrutiny
By Paul Homewood
Yet another attempt to “prove” that rainfall is becoming more extreme in the UK:
https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl.1033
This is the key graph:
United Kingdom’s wettest day of the year. (a) Timeseries of UK mean Rx01 anomalies relative to 1961–1990 from observational data. The observed anomalies in 2020 and 1986 are marked by a cross
The first thing to note is that they are looking at the UK as a whole. We know that Scotland has become considerably wetter in recent years, but what about the rest of the country?
If we analyse the England & Wales Precipitation Series, we actually get a totally different picture:
Note that 3rd October 2020 was a long way from being the record claimed for the UK. (There are concerns with the HADUK dataset, as it now includes many high altitude sites not previously available, which will inevitably bias the results to wetter. The England & Wales dataset, though based on fewer stations, has greater consistency).
Although there is a tiny trend of 0.03C pa, ie 3mm per century, this is well within standard margins of error. The R2 is only 0.024, which is regarded as a very low correlation statistically.
Clearly the trend line is heavily skewed by two outliers in 1986 and 2000, neither of which can be construed as “current climate”.
It is also apparent from the data that there was step change around 1960. Consequently when we begin the series in 1960, there is actually a declining trend. Interestingly, the UK chart also shows this decline, once the 2020 outlier is excluded.
Whatever the reason for that step change, it clearly has no bearing whatsoever on what is happening now, or might in future.
What we can safely say is that there has been nothing unusual at all in the last two decades, which is surely the time when global warming should be impacting heavier rainfall, if the theory is correct. Indeed, it is the 1960s which stand out as being most affected, with four years, 1960, 1967, 1968 and 1969 each seeing daily rainfall totals more then anything seen since 2000.
It may be that Scotland is seeing more extreme rainfall, which the KNMI data seems to suggest:
However, the fact that England & Wales are not seeing the same increases totally discredits the theory that a warmer atmosphere is driving heavier rain. Instead we need to look elsewhere for the factors behind Scotland’s weather.
So often in climate science, we come across shoddy studies like this one, where it is evident that the authors have decided on the conclusions at the outset, and then manipulate the data until it agrees.
Comments are closed.
NOT A LOT OF PEOPLE KNOW THAT 
Further point is that over the period analysed, are all the rainfall measuring stations the same ie no new ones introduced?
These types of “records” are only valid if the recording system is static over the entire observation period. Changing the number or location of any stations invalidates any claim of a record.
Its also worth noting that the paper states:
“In a warming climate, the atmosphere can hold more water vapour in line with the Clausius–Clapeyron relation, and wet extremes would therefore be expected to become more intense”
My understanding is that a package of air simply being able to hold more water does not necessarily translate into more intense rainfall – any one a physics specialist or meteorologist who can commnet further?
Yes, I understand you need something like the moisture laden air to move over higher ground, especially mountain ranges or the other method is the collision of air masses of different temperatures
The potential concern I have is are they using a ‘consistent sample of stations’ over the years? The problem with an aerial average for the UK is that this includes (theoretically) everything from dry lowland areas of the UK (The Fens, Thames Estuary etc), through to mountain and remote and wet locations (Lake District fells, Snowdonia, Highlands). Now the thing is that the way we measure rainfall has changed in very recent decades. Up until even the turn of this 21st century the official rainfall statistics came from manual 5 inch diameter Met Office/ Snowden standard rain gauges that were first developed in Victorian times. They were manual in the sense that someone had to read them daily at 9am. These data were supplemented by ‘monthly’ gauges, which were only read on the first of each month (and hence only have a monthly total). Nowadays – and this is only a feature of the last couple of decades – the Met Office has a network of automatic raingauges that record pretty much without an observer having to read the gauge manually every day. This brings a bias – what I might call the Honister Pass factor (the famed location in the Lake District of recent daily rainfall ‘records’). In the old days the manual recording method for rainfall biases the recording of daily rainfall totals to areas close to habitation and/or in places where an observer was on site and could read the gauge each morning – by default this would tend to be the lowland, more sheltered and drier locations. Nowadays we can measure on a daily basis the ‘Honister Passes of the country – remoter, higher and wetter locations, that will tend to have higher rainfall. If you are sampling nowadays for the country as a whole you will be capturing rainfall totals from places for which daily records didn’t exist before. Referring back to the Honister Pass rainfall gauge again, I am pretty sure that rainfall has been measured here for a long time, but that the records for decades were monthly readings only, whereas now we have daily readings in this very wet location. The other risk is that we have computer modelling gone mad or producing the result that everyone wants.
Final point – the paper is also using gridded observations for the UK. That immediately adds further warning flags – the gridded data is no longer an observation set but a locally interpolated estimation.
As someone who actually is an expert in geostatistical gridding techniques I can say with confidence that using a gridded dataset may lead to entirely unwarranted conclusions. One of the reasons I prefer HadCrut rather than GISS global temperature datasets.
Paul Homewood the following link may well be off topic a little and but may have some relevance:-
https://www.nottingham.ac.uk/news/human-induced-climate-change-shown-to-influence-global-river-systems-new-research
The paper referenced by the paper which reports on the UK gridded datsets inlcudes the following comment:
“The result is a dataset of key UK climate variables of up to 1km resolution”
The paper makes the classic error of assuming that infilling a grid to a certain sample rate (ie gridding) results in the same resolution. Resolution cannot be increased by interpolation – it would imply we gain information by interpolation about something never measured.
The UK land area is stated as about 240,000 km^2. The temperature grid dats has between 100 and 600 stations depending on the time period. The best resolution is therefore 400 km^2 or 20 km.
For the rainfall data they claim up to 5,000 stations. That gives a maximum resolution of about 48 km^2, or 7 km.
Of course the resolution is also variable as a function of time as the number of stations varies up to 5-fold.
These things matter.
Omitted the referred paper
https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/gdj3.78
They do use “objective interpolation” .
I looked at this and its various data sources some time ago. My understanding at the time I read it, was that the uncertainty band of the study contained the result of no change at all.
So whatever happened or happens they will be correct.
Scotland’s rainfall rise is interesting. What are the excuses – sorry reasons – for it ?
Most likely the jet stream tracking north
The increased rainfall in Scotland seems to correlate with the rise of the SNP. Obviously this demonstrates causality.
Here’s xmetman’s take on it –
https://xmetman.com/record-breaking-rain-more-likely-due-to-climate-change-except-in-northern-scotland/
Shows that metoffice is almost as bad as BBC
EVERY sentence of the Abstract shouts “junk science!”
‘Data from large multimodel ensembles indicate that the moderate historical trend towards wetter conditions will emerge more strongly in coming decades’
Junk!
‘while a notable anthropogenic influence on the variability of the wettest day may be identified as early as the 1900s.’
Junk!
‘Experiments with different forcings are employed to estimate the changing probability of extremes due to anthropogenic climate change in a risk‐based attribution framework.’
Junk!
‘We introduce a new methodology of estimating probabilities of extremes in the present and future that calibrates data from long simulations of the preindustrial climate to the mean state and variability of the reference climatic period.’
Junk!
I can translate: “Our predictions of the future are better than others’ predictions of the future. Cos reasons.”
The future isn’t what it used to be.
+100.
Those sentences are classic ‘blinding with science’ jargon.
In plain English they used models to arrive at their predetermined conclusions.
” The future isn’t what it used to be “…. they arent even using existing real data from the past, as of course computer models can do that for them under the catchall “simulations”
” that calibrates data from long simulations of the preindustrial climate “
Its grim up North.
Should we be more careful in eliminating data that fails to demonstrate what we want to prove? Isn’t that what the “alarmists” are often accused of?
“UK stats aren’t what we like” – leave out Scotland. “Early 1900s don’t look good” – let’s start at 1960 (exactly what the warmists are always doing so this must be avoided). “Reasons for Scotland stats” – jet stream tracking north (for 120 years?).
I’m trying to demonstrate the weakness of the global warming case to several unconvinced colleagues at present – arguments need to be water-tight. Some data for the climate change hypothesis will always point the other way, let’s stick with the facts until they are overwhelming.
Unfortunately we are going to have top-level gatherings in the UK that will emphasise the belief in human CO2 emissions. There needs to be much rock-solid evidence to discredit this, and a way of publicising it. Otherwise Extinction Rebellion will have a field day.
You misunderstand Terry
I am simply pointing out there are no trends in England & Wales, which undermines the whole of their theory. And if there was a rising trend from 1931 to 1960, and then a falling trend, then does exactly the same thing
Many thanks, Paul. I certainly agree that data at all levels should be examined. Some will not agree with the overall case simply because it gets more variable and random the smaller the dataset, and it’s the total picture that counts.
Meanwhile I watched a short video lecture by Matt Ridley from 2016 yesterday giving a wonderfully positive slant on the next hundred years. Should be obligatory viewing for everyone who wishes to voice an opinion!
I think you will have job trying to convince your colleagues. I mistakenly tried it on a long standing friend of some 60 years. An intelligent learned man not known for illogical outbursts. As soon as I opened the subject I was told that “anyone who doesn’t believe in global warming must be stupid” There was no way that he was going to accept any argument to the contrary. The reason I follow this blog is exactly as you say, to gather all the information I can. but being too dogmatic loses the arguments in both directions. Well done to Paul for being so persistent. Its just a pity we don’t have another Christopher Booker to spread the counter argument in the Media.
It never ceases to amaze me that intelligent people who know that 99% of science over the centuries has proven to been wrong still cannot be sceptical about today’s science.
Thanks, Bob, I’m sure you are right. No reason not to try, though, there must be a few undecided out there! Your friend is a prime example of how a lot of people want to accept the majority view. In addition, I also hold the view that there are many people who want to believe that they are living in a very important time for the planet and can do something to avert a crisis.
They are not amenable to the argument “no, you live in a very calm and beneficial environment, just do what you can at a local level not to spoil it”.
Unfortunately the drama queens rule the roost at the moment.
But that’s how science works. You can’t claim the UK is getting wetter is much of it isn’t. If Scotland is much wetter that’s what’s happening. Then you find out why Scotland is getting wetter but England isn’t. You will never find out what’s happening if you try and find out why “the UK” is getting wetter, because it isn’t. We are not excluding data, because we are agreeing Scotland is wetter. A theory has to explain what is actually happening at every level you can take the data to.
The early England and Wales precipitation data has biases, making trend conclusions suspect, see this paper:
“Multi‐century trends to wetter winters and drier summers in the England and Wales precipitation series explained by observational and sampling bias in early records”
https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.6208
Having said that, wetter winters will always be warmer winters, oh the horror: winters are warmer than they were during the pre-industrial Little Ice Age.
I have thought to ask the question
‘Does mankind control the tides?’
Answer ……’No’
Then, ‘Does mankind control the climate?’
Answer ……erm
At least it makes the eco’s cough a bit.
The idea a model can forecast “the wettest day” is such utter nonsense even the Clinate loons should throw this out. You might look at running 24 hour averages but never at a “day” – what’s remotely “climate” about midnight?
Not even a decent children’s project piece of work.