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Discussion > What's The Difference Between Measured UHI and Met Office weather forecasts

Mark Hodgson

Regrettably the problem is on your side.

You express an opinion that the effect of UHI is underestimated, with no supporting evidence.

I I calculate the probable effect of UHI globally, and then regionally (at your request).

You do not critique the calculations. You do not provide figures of your own. You reject my figures and Venema's on grounds of personal incredulity and conspiracy.

The is not how a scientist argues. It is how the political sceptics, the denialisst and the deluded argue. Once again I have wasted my time

Oct 22, 2016 at 9:59 AM | Unregistered CommenterEntropic man

Alarmism was doomed from the start. It's just been a matter of how long the charade could continue.

Oct 22, 2016 at 11:18 AM | Unregistered Commenterkim

You didn't understand natural variability from the beginning, and you bluffed with nonsense like the Hockey Stick, and pitifully warped models.

Oct 22, 2016 at 11:48 AM | Unregistered Commenterkim

Entropic Man, the problems are actually all on "your side". The whole Global Warming Alarm fiasco was not started by anyone else. You or "your side" have lied, lied again, and then lied to cover up the previous lies.

"Your problem" is that taxpayer funding is drying up. That is not a problem for anybody else, apart from the fact that 97% of the money has been wasted, and the climate has not changed any more or less than it has always done, without man's interference. If the "climate" is 1 degree warmer than 150 years ago, who cares?

Oct 22, 2016 at 1:16 PM | Unregistered Commentergolf charlie

The very harsh winter of 1947 really hit the UK and other parts of Europe very hard, as people were trying to rebuild after WW2. The snow and ice all melted very suddenly when it warmed and rained, bringing the worst flooding of the 20th century to many areas of the UK.

Thankfully we have not had a repeat of 1947 conditions.

The second worst winter was 1962/3. Thankfully it has not been repeated either.

Why don't climate scientists celebrate the fact that these two weather catastrophes have not been repeated for over 50 years? Or the summer of 1976, or storm of 15/16 October 1987? The weather is not as cold or extreme as it used to be, but if anyone of these events is repeated, it will be "proof of Global Warming as predicted by Climate Scientists".

Cold kills people. Cold kills animals, livestock, plants, crops, fruit tree blossom. The UK climate has not got hotter, it just doesn't get as cold, as often. UHI is involved in recording record high temperatures, but these are false.

Oct 22, 2016 at 2:58 PM | Unregistered Commentergolf charlie


The problem is very much on your side. I have offered detailed critiques of the papers introduced by you and Phil C in defence of the proposition that UHI is not an issue, and neither of you have dealt with them. Your "calculation" of the probable effect of UHI is back of the fag packet stuff which ignores the enormous holes and inconsistencies in the papers.

Those papers say that the country is warmer than towns, that airports are cooler not warmer, that despite the country apparently being warmer than towns they have made adjustments to counter the effect of towns being warmer than the country, and anyway towns are only really big places, not middle-sized towns ofupto 50,000 people. Tokyo demonstrates a UHI effect of 2C but there is no UHI to worry about. On and on it goes. Unmitigated drivel, and you apparently can't see it.

I repeat, the problem is on your side. The real shame is that there are "sides" at all. The application of a little common sense could resolve many of the issues between us, but that needs you, and people like you, to open your eyes first.

Oct 22, 2016 at 3:42 PM | Unregistered CommenterMark Hodgson

In answer to the original question from SandyS, UHI produces record breaking high temperature records for climate scientists, BBC, Met Office et al to go "Ooh! Global Warming!"

If the BBC or Met Office et al have ever included a UHI Caveat to any of their Ooh reports about Heathrow temperature records, I must have missed it.

This is "dishonesty", but where would Climate Science be without dishonesty?

It will be interesting if the Met Office return to honest reporting having lost the BBC Contract.

It will be interesting to see how the BBC's new weather forecasting service provider, enables better delivery of service, to the taxpayers that pay for it, or whether the Contract Managers at the BBC have decided they want more "Ooh! Global Warming" stories to broadcast.

Oct 22, 2016 at 9:03 PM | Unregistered Commentergolf charlie

Seems to me that UHI adjustment values are taken by a coverall average. A bit like in the English Premier League taking the average points each team has taken during its existence and saying that Leicester City can never win the championship. In reality we all "know" that in the alsorans there will be teams that have a brief flowering of success followed by a return to normal. Sometimes something will happen to a Chelsea (resiting the Abramovich thermometer) or Manchester City which means they will have a sustained period at the top after decades of unexceptional performances. Anyone studying statistics only and have total belief that numbers never lie will be surprised at these unexpected peaks, anyone only interested in football won't, anyone not particularly interested in football but a follower of news and history will not be surprised either. This also explains the Met Office having two (possibly more) incompatible views on UHI, one branch is convinced their models and statistics are correct, the others actually follow weather and climate.

Explaining my problem to Entropic Man and getting him to understand what the issue is is proving beyond my capabilities.

Oct 24, 2016 at 9:46 AM | Unregistered CommenterSandyS


You are right. I do not understand what you are trying to say.

The football analogy is daft. Weather stations are not competitive. They do not have "good year"or"bad years". Nor does an increase in the average from one station necessarily mean a decrease in average other stations

Also, the average number of points scored per team across the league will be constrained by the number of teams and the number of matches. It would be constant down the years.Weather stations, urban and rural, are showing an overall warming trend.

If this is how you think that urban and rural weather stations are actually behaving, perhaps you should sit down and rethink your concept of UHI. Football is not physics. Your mental model does not match the physical reality.

Perhaps I can make my own viewpoint clearer.

You mentioned the difference in approach to UHI of different departments in the Met Office. I am not surprised.

The weather forecasters are interested in weather conditions day by day. When forecasting the temperature in Parliament Square they will calculate the UHI expected for that day. It will be higher on a bright sunny still day, lower on a wet windy day. In the former case the UHI warming relative to rural Kent will be considerable. In the latter case there may be no difference.

Those studying long term climate trends will have a longer term perspective. They want to be able to compare annual average station data from 1915 with 2015 data from the same station, perhaps the Greenwich Observatory. For that they need to filter out the UHI from the annual average. To do so they compare the annual averages for Greenwich and the nearest rural station.

Suppose that the annual average for the rural station has warmed by 1C and Greenwich has warmed by 2C.

That means that the average for Greenwich has warmed by 1C due to UHI, indicated by the difference between the two stations. The climate researchers can then subtract the UHI effect, leaving the residual 1C change due to changing climate at Greenwich.

Oct 24, 2016 at 12:04 PM | Unregistered CommenterEntropic man

Entropic Man, your logic is daft. How can you assess Leicester City's performance last season, by averaging out their positions over the last five seasons, adjusting them upwards to exaggerate and demonstrate a progressive rise?

I am not a football fan, but it occurs to me that Climate Scientists are a bit like football pundits working for bookmakers. Trying to fix the stats, to prove yourself right is not science.

Climate science needs to adjust it's mindset to match what is considered acceptable behaviour.

Oct 24, 2016 at 12:13 PM | Unregistered Commentergolf charlie

Golf Charlie

Football is SandyS ' analogy, not mine. Talk to him about it.

Oct 24, 2016 at 12:22 PM | Unregistered CommenterEntropic man

Entropic Man, your logic is daft. I know the Football analogy was SandyS.

Climate Science remains incapable of finding it's own mistakes, but is quick to find fault with everyone else.

Oct 24, 2016 at 12:55 PM | Unregistered Commentergolf charlie


I completely accept, of course, the logic of your statement:

"Suppose that the annual average for the rural station has warmed by 1C and Greenwich has warmed by 2C.

That means that the average for Greenwich has warmed by 1C due to UHI, indicated by the difference between the two stations. The climate researchers can then subtract the UHI effect, leaving the residual 1C change due to changing climate at Greenwich."

Your logic is, to me, unimpeachable. My problem is that it isn't at all clear to me that this is how it works in practice. For instance, the following quote from the abstract of Petersen's 1984 paper:

"Contrary to generally accepted wisdom, no statistically significant impact of urbanization could be found in annual temperatures."

In other words,Petersen is saying there is no UHI, so nothing to adjust.

I'm sorry we had a falling out about your claim regarding 3% of the earth (or at least land) being urban (or words to that effect). I didn't respond as calmly and as clearly as I would have liked. I should have quoted from the Berkeley Earth Project paper linked to by Phil C, which said:

"Urban areas are heavily overrepresented in the siting of temperature stations: less than 1% of the globe is urban but 27% of the Global Historical Climatology Network Monthly (GHCN-M) stations are located in cities with a population greater than 50,000. If the typical urban station exhibited urban heating of the magnitude of Tokyo, this could result in a severe warming bias in global averages using urban stations."

That was why I argued that your 3% claim was a sleight of hand ("lies,damned lies, and statistics"). It is also why I made the point that 50,000 seems to be regarded as the point at which UHI might kick in, whereas the reality is that it kicks in where towns are much smaller. The town in which I live has fewer than 10,000 people but it is warmer than the surrounding countryside (I used to live just over 3 miles out of this town, and on winter nights if I came into town then went home again, it was noticeably colder in the countryside). I appreciate that is just my personal and unscientific observation, but our views are formed by our personal experiences. Our local ITV (Border) weather forecast has been forecasting temperatures of 5 or 6C colder overnight this last week in the countryside compared to "towns and cities". Given that we only have one town/city in the Border TV region with more than 50,000 inhabitants (Carlisle) it seems clear that the ITV weather forecasters are acknowledging a significant UHI effect in towns smaller than that.

And the Berkeley Earth Project in effect said the same as Petersen - there is no UHI effect. What else do these words, quoted from the Berkeley Earth paper, mean? "In Table 1 we see evidence of “global warming.” Using all the
records there is a median warming trend of 0.96 ± 0.04°C/100yr (2σ error). The estimated warming trend for the very-rural group is larger than that based on all records, in the opposite direction expected from urban heating. "

In other words, there is no UHI. The conclusion obviously is that they also think there is nothing to adjust.

To sum up my concerns therefore:

1. As conceded (but only in respect of towns/cities with more than 50,000 inhabitants) by the Berkeley Earth Project, large towns and cities are massively over-represented in the datatsets; but

2. They do not concede that UHI is real.

Therefore how can we believe that the adjustments you so correctly and logically argue for, are in fact been made - in full and in respect of all sites where adjustments should be made to reflect UHI effect? My concern is that those adjustments are not being made fully to allow for it, i.e. not made to the extent required (in terms of degrees C); and not made in respect of sufficient sites where it has an effect.

Oct 24, 2016 at 7:58 PM | Unregistered CommenterMark Hodgson

We should use the 'best' station in each country. The one that has not been moved or altered in any way shape or form (if possible).

We could then, possibly, consider merging this temperature record with a similar best station record in other countries.

Why this way?

Whenever you adjust and/or merge/homogenize records, you have to make value judgments that can be argued with.

One regional temperature should be less controversial?

Oct 24, 2016 at 8:54 PM | Unregistered CommenterSteve Richards

Mark Hodgson, Steve Richards

I think the key word in both Peterson and Berkeley is "significant". ie that the difference you see has a genuine cause and is definitely not noise.

They are not saying that there is no UHI. They are saying that over a year ignoring UHI does not produce regional averages which are significantly warmer than if UHI is homogenised out.

If the variation due to UHI is not large enough to be clear!y distinguishable from the normal variation, it is difficult to homogenise it and it might not be worth bothering to do so.

I know this is a statistical argument, but it says the same thing as my own calculation. When you examine the numbers, UHI has only a small effect on larger averages. The researchers have tried to get the best handle they can on UHI and found it exists as a local phenomenon, but is not the dominant cause of the observed global changes.

The problem of urban bias in the available stations is an old one. As was said earlier stations tend to be where people are. For many years NCDC have used a list of stations known as gchn.v2. These are chosen for length of record, reliability and stability.
GISTEMP use a slightly different list, gchn.v3

If I were choosing stations for a product of my own, I would still prefer to use rural, small airport and small towns rather than stations from the centre of large cities.

IIRC the gchn lists use about 1500 stations out of the 4000+ available. For the global averages this is a large enough sample that the uncertainty in the monthly mean is entirely due to external variation, not the uncertainty due to small sample size.

I have some background in statistics. When I read the various papers and online information l get an impression of the dataset compilers attempting to produce the best global averages that the available information allows. Uncertainties are quoted( around +/-0.1C for most of the global averages) and both raw data and code are publicly available .

To those without mathematics there is a temptation to see statistics as a way of creating a false impression. In practice statistics is quality control for data. Like any other language, you need to work to understand it properly.

One thing statistics is particularly good for is telling the difference between subjective impressions ( Ely is warmer than the countryside around it) and differences in the data (The station in Ely does not have a significantly warmer average temperature than the station at Wicked Fen.)

Oct 24, 2016 at 10:40 PM | Unregistered CommenterEntropic man

Entropic man
Now you understand my issue with UHI adjustments as performed by Climate Science. They make no sense in the real world.

Oct 24, 2016 at 11:39 PM | Unregistered CommenterSandyS


Why do you say that? Do you have data or is it just a subjective opinion? I discussed the difference above.

Results of a proper analysis would have more credibility than a gut feeling, particularly given the problem that gut feelings are influenced by irrelevancies like expectations and politics.

Oct 25, 2016 at 12:02 AM | Unregistered CommenterEntropic man

Using statistical trickery, adjustments, homogenisation etc Climate Science can prove whatever it wants, and get it peer reviewed.

This has been Climate Science's greatest achievement.

When banks make errors that are not in their favour, they correct, and claw back money as fast as they can. Climate Science always adjusts in favour of more money, for Climate Scientists, at taxpayers expense.

Oct 25, 2016 at 12:09 AM | Unregistered Commentergolf charlie

EM, we are still stuck with climate science's "gut feeling" that CO2 is the planet's temperature control knob, which can't explain the LIA and MWP, let alone anything before or since.

Oct 25, 2016 at 12:15 AM | Unregistered Commentergolf charlie

That alarmism has become dependent upon fraudulent manipulations like Gergis and like Karl signifies that the end is nigh. The skeptical commenters you see are the tip of the iceberg of gut felt doubt. That iceberg is viscerally feeling the damaging results of the harum-scarum, and is beginning to be revolted. Being fooled and ripped off does not sit easy on the stomach.

You alarmists had your run; you'll soon have to run and hide.

Oct 25, 2016 at 12:18 AM | Unregistered Commenterkim

EM, I remember the last 3 months of 1997 very well. It was warm and dry, and leaves were still on trees as I drove in and out of London along the M4. Low sun in my eyes driving to work in the morning, and driving home. There were many shunts on the M4. In the garden at home where I was then living, a rose was in flower on my mother's birthday in December. I believed in the concept of global warming then, and my gut feeling and experience at the time backed it up.

I think I did know about nino/nina at that time, but only in relation to it's effect on the West Coast of South America.

Oct 25, 2016 at 12:39 AM | Unregistered Commentergolf charlie

kim, they will be able to carve permanent homes to hide in, out of Arctic ice. Providing they can prevent their diesel fuel from waxing up in the cold, they can generate heat and power.

Oct 25, 2016 at 12:44 AM | Unregistered Commentergolf charlie

Being in a position currently where I find it relatively easy to read and absorb rather than comment myself I'll simply say that reading the 5 currently active discussions has been a really great pleasure, full of fascinating pieces of info, some on topic, others not. Last night's efforts having been particularly appreciated. Picking out an individual's contribution would be invidious, but I shall indulge myself. EM you can be fascinating when not pushing your climate agenda.
Thank you, one and all.

Oct 25, 2016 at 8:26 AM | Unregistered CommenterACK

Entropic man,
Hopefully not a gut feeling, but influenced by a lifetime spend measuring stuff. Where controlling the environment where the measurement is taken is vitally important to getting repeatable results. Checking the values of voltage and temperature given by equipment sensor were regularly verified against regularly calibrated meters. When spending billions of government money I'd expect similar if not better standards to be applied to meteorological measurements.

I'll have another attempt at explaining in a way that we'll both be happy with.

Most temperature measuring stations are urbanised areas. These stations are affected by non-CO2 higher albedo temperature variations (here after ATV). These variations are dependent on the weather conditions prevailing at the time of measurement. On days where there is significant wind (what that is depends on station siting amongst other things) the ATV will be small and perhaps unmeasurable, On low wind days (again difficult to quantify) the ATV will be high, several degrees in Met Office weather forecasts. These low wind days constitute about 70-80 days in Europe. Taking the difference for all days and averaging it across 365 days then working out how much that average has changed in the last decade/century/lifetime of the station or whatever period doesn't give a true value how the ATV affects the measurements. For 20% of the measurements there will be very large errors if an annual ATV adjustment is used when a daily weather condition one should be used.

The daily adjustment for ATV must be different for each station because of the number of variables involved. These variables will include but not restricted to wind speed, wind direction, cloud cover, season of the year (foliage affecting wind), snow cover, frost cover (the white stuff on the ground), fog and precipitation at the time of measurement. Not all of these will necessarily lead to a positive ATV in urban environments. Don't really know the influence of any individual factor on any particular day.

Going back into historical records to make adjustments on these lines will be extremely difficult if not impossible, including them in future measurement will also be difficult. So any adjustment is a guess based on gut feeling and experience.

Oct 25, 2016 at 9:13 AM | Unregistered CommenterSandyS


Petersen did indeed say "no statistically significant impact of urbanization could be found in annual temperatures." However, I don't believe the Berkeley Earth Project used that qualification. It said: "The estimated warming trend for the very-rural group is larger than that based on all records, in the opposite direction expected from urban heating. " So it actually went further than saying there is no UHI - in effect it said there is RHI ("Rural Heating Effect") or UCI ("Urban Cooling Effect"). Patently such a conclusion does not sit with what we know to be the case (do we "know"; is it a "gut feeling"; or is it "a subjective impression"?).

I totally understand where you're coming from. I hope you understand where I'm coming from. I obviously haven't been able to persuade you that results in papers which differ from reality are not persuasive. You have not been able to persuade me that adjusted statistics which differ from my perceptions (I'm tempted to say which differ from the real world) mean that UHI is insignificant.

It's been fun (and educational, for me at least) airing the issues. Perhaps we shall just have to agree to differ.

Oct 25, 2016 at 9:15 AM | Unregistered CommenterMark Hodgson