Whenever the Met Office publishes their UK temperature charts, they never show any margins of error. [emphasis, links added]
This in itself is poor statistical practice.
And as we now know, most of the Met Office’s temperature recording network have very high levels of uncertainty because of poor siting.
According to the WMO, class 3 measurements are only accurate to within a degree. Class 4 and 5s, which account for 77.9% of weather stations, have uncertainty up to 2C and 5C, respectively.
If we average this together, poor siting could be artificially overstating the Met Office’s UK temperature averages by 2.5C.
Usually in other fields, negative and positive errors would tend to cancel out, due to their random nature.
With temperature recording, however, poor siting nearly always adds to underlying temperatures. If the Met Office had published these error margins, their annual temperatures would have looked like this [click to enlarge]:
I am not saying that the error margin is necessarily as big as 2.5C, only that in theory it might be.
But with the predominance of poorly sited stations, it is abundantly clear that the Met Office cannot scientifically claim to know the current average temperature of the UK to a hundredth of a degree.
For the sake of this exercise, I have only shown the error margins for the years since 2010, as we can reasonably assume the existing mix of stations applies throughout that period.
[Of course, going back in time we have no idea of the mix of stations or how badly sited they were. More importantly, neither does the Met Office].
That of course means that they have no means of knowing whether they are comparing like with like when they publish temperature trends going back to 1884.
[Therefore,] they cannot say with any degree of scientific certainty that the last two years were the warmest on record, nor quantify how much, if any, the climate has warmed since 1884.
Read more at Not A Lot Of People Know That
Are those Weather Stations set up in a Asphalt Parking lot or heat exuast vent? And are they screwing around with the increments?