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Discussion > Urban Heat Island Effect - Is It Real?

ACK 11:20 & 11:56 both valid points. Many races/cultures, including the Arabs have valued fresh water as a scarce commodity. Being able to have water features was a show of wealth, but the cooling effect of spraying water into the air also provided cooling, especially in outdoor courtyards.

This became a standard for many cultures with the ability to channel or pipe water, and the redevelopment of parts of Barcelona for the Olympic Games included many water features as external airconditioning, in Moorish tradition

Sep 17, 2016 at 3:09 PM | Unregistered Commentergolf charlie

Part of the problem with recording and/or adjusting UHI is the very simple and traditional technology of a MAX/MIN thermometer, still used by gardeners today. They don't record AVERAGE temperatures.

It only takes one daily artificial spike to create a MAX temperature, and in an urban environment, with cars, airconditioners, tarmac, heating flues, kitchen extract fans etc, there are far more artificial spikes to record, over and above the manmade environment that naturally creates warmth.

Every time the Met Office releases a new record for Heathrow Airport, my contempt for the Met Office achieves a new MAX.

Record high temperatures are great for selling more airconditioning systems in urban areas, and, amazingly, some of these create new record UHI records. Conflation of cause and effect is a profitable business.

Sep 17, 2016 at 3:29 PM | Unregistered Commentergolf charlie

Thanks, all, for your thoughts, with which I am in complete agreement.

I think RR is correct in saying, broadly, that to re-establish some credibility, we need to start measuring at locations that are unlikely to change much, measuring at consistent times of day, without changing the equipment we use to measure temperatures etc; also gc makes a good point about needing to measure average temperatures, rather than simply maxima and minima. If this could be achieved over a period of, say, 20 years, thereby obviating the need for adjustments, then maybe - just maybe - we could start to trust the temperatures recorded, as reported.

Unless and until that happens it seems to me none of the temperatures as reported can be regarded as 100% trustworthy, however well-intentioned the adjustments that are made to them. The long and the short of it is that any claim that we have precise temperature records because adjustments and homogenisations deal with any "issues" is simply untrue. For a start, it assumes that we understand every single factor that might influence temperatures as recorded, in an arbitrary way, when patently we don't. Secondly it assumes that even if we did have such understanding, we also have perfect understanding of the precise adjustments that are necessary to counter-balance those arbitrary factors. Again, patently we don't, however much some might like to think that we do.

Which means - if we don't know for sure what's happening to the world's temperatures, why all the hoo-ha and the expensive and disruptive policy prescriptions?

Sep 17, 2016 at 3:48 PM | Unregistered CommenterMark Hodgson

The surface data collected to date has been so mangled by “homogenisation” that it is rapidly becoming worthless. Part of the problem is that it involves so many instruments, from so many sources, allowing for variable levels of calibration, situated in so many questionable places, with no uniformity of distribution, read by unverified people, often at unspecified times. Perhaps it is time to reduce all of these factors, with any combination of any or all introducing a plethora of potential errors; the only way that is obvious, to me, is by using satellites. These restrict the number of instruments used, the source of these instruments, and their calibration (one, I would have thought), with constant monitoring of the entire surface, limited only by the rate of pass over the surface. Admittedly, this will take some time to establish the data-set.

One of the benefits of this is that during this time, many of the proposed catastrophic policies can be put on hold.

Sep 17, 2016 at 8:52 PM | Registered CommenterRadical Rodent

One of the benefits of this is that during this time, many of the proposed catastrophic policies can be put on hold.

Sep 17, 2016 at 8:52 PM | Radical Rodent

NO! We need massive cuts in climate science funding NOW! If it turns out to be catastrophic for climate science, I'll get over it, and the climate won't even notice.

Sep 17, 2016 at 9:27 PM | Unregistered Commentergolf charlie

Mark Hodgson, something I have posted about before ...

Sports clubs, stately homes etc have been recording temperatures for a few hundred years. Thermometers may not have been calibrated, but a critical factor has always been "was there a frost last night?" Either yes or no, and then, when was the last and first frost of each year? No thermometers required.

Vineyards around Europe may have similar records, along with their stately homes with ornate gardens and farms.

I have no doubt that trends would emerge over a few centuries, and I have no doubt that there are fewer frosts than 50 years ago. But 100 years ago? 150 years ago? 200 years ago would take us back to the aftermath of Waterloo, and just before the steam age.

2 well known Stately Homes would be Blenheim Palace and Chatsworth. They both have artificial lakes/ponds.

UHI has always involved man's effect on increasing temperatures. I am not aware of how man can have increased the likelihood of a frost pocket forming. A record of frosts and/or ice on water would be more crude, but a more reliable assessment of temperature change over decades, than anything involving artificial adjustments.

Sep 17, 2016 at 9:55 PM | Unregistered Commentergolf charlie

GC: I thought that was what I was saying….? Oh, well… one day I shall master this English language stuff.

The policies being proposed – and even implemented – to "counter climate change" are little short of catastrophic, engineered to end Western civilization. If we can find a way – any way – to postpone or otherwise halt these policies, then such ways should be used. Demanding that we wait until we have viable long-term readings from satellites seems a good start; hopefully, by the time we get to the point when someone asks: “Do we have enough, yet?” the whole scam will have been exposed, and no-one will touch it with a barge-pole.

Sep 17, 2016 at 9:58 PM | Registered CommenterRadical Rodent

GC, your point about frosts is a good one, and I have asked similar questions elsewhere with no good replies forthcoming.

The freezing point of (fresh) water should leave many an indelible mark in historical temperature measurements. A true scientist seeks out these kind of internal standards. I suspect such 'gate-keeping' would not attract much funding or many students in today's climate activities.

Sep 18, 2016 at 12:16 AM | Unregistered Commentermichael hart

' to "counter climate change"' They usually don't say counter, because that would be impossible. They ought to say is 'mitigate the effects of'', because that fits their narrative best. What they do say is 'tackle'. Whenever a politician uses the word tackle he is betraying his agenda. That the thing to be tackled is a political football. The issue, the real or imagined problem, is to be tackled with initiatives, regulations and funds. It is not to be fixed. That would be to waste the opportunity it presents. Next time you hear that word from a politician you will know what it really means.

Cynical? Moi?

Sep 18, 2016 at 4:15 AM | Unregistered Commenterrhoda


As michael hart says, your point is indeed a good one. I just wish I had the time, expertise, and enthusiasm (and funding - funding would be nice!) to follow up on these thoughts and do something about it. But I don't, so unless someone else does, I don't suppose we'll get anywhere.

One thing's for sure - the "consensus" won't be following up on your ideas...

Sep 18, 2016 at 9:26 AM | Unregistered CommenterMark Hodgson

Wisden could be consulted to see how many early season games were abandoned by late snows. Still seems to happen most years, despite claims that snow will become an "unusual" event.

Sep 18, 2016 at 10:24 AM | Unregistered CommenterACK

ACK, I was working abroad in 2008, and was chatting to a Brit who was on the Committee of his English village cricket club. He had done that exercise for the records of his own club, and concluded that summer 2008 was the wettest on record, for matches cancelled or abandoned. The records he was able to go through in the clubhouse on another sodden saturday went back to the early 1900s.

2008 was pre-ClimateGate, at a time when I thought I was the only one who thought there was something wrong with climate science statistics. In the 1990s, BBC Gardeners World was full of comments about preparing for hotter and drier summers because of Global Warming ........

For those involved with caring for, or earning their money from the soil and land, frost in the UK is significant enough to be worth recording. Similarly, how many times have we been told that orange juice will be more expensive due to late frosts in Florida? If late frosts in Florida are less common, then fine, another benefit of a warmer climate.

Wnen it comes to UHI, RAF Benson in Oxfordshire regularly records the lowest English temperature. It is in a frost pocket within the Thames Valley part of the Chilterns surrounded by rural scenes and farmland. The Met Office has records of data there, but would rather highlight the "Highs" at Heathrow 40(?) miles away, a known UHI.

The Met Office must have some unadjusted records for RAF Benson......

Sep 18, 2016 at 12:21 PM | Unregistered Commentergolf charlie


Thanks for your observation about Tokyo (I watched the programme too). It does tie in with Petersen's tentative conclusion (again as summarised in his abstract):

"It is postulated that this is due to micro- and local-scale impacts dominating over the mesoscale urban heat island. Industrial sections of towns may well be significantly warmer than rural sites, but urban meteorological observations are more likely to be made within park cool islands than industrial regions."

In fairness to him (and I am trying to be fair) his conclusion (which is tentative - "it is postulated that...") might be correct in respect of the limited series of sites his study investigated, but it's not appropriate to draw from that the big conclusion ("but urban meteorological observations are more likely to be made within park cool islands than industrial regions"). Nor is it appropriate for an inappropriate conclusion, tentatively drawn, to be cited more than 200 times as proof that the UHI effect isn't real. But when did any of that stop climate science?

Sep 19, 2016 at 8:49 AM | Unregistered CommenterMark Hodgson

Wrong again at least for the cities I was thinking about - desert cities in SW USA. There is no reverse UHI effect, in fact rather the reverse. Las Vegas and Phoenix have very prominent and increasing UHIs

Spencer attributes this to air conditioning and the surfaces in cities absorbing heat (and losing it at night) more than surrounding desert surfaces.

Now I'm wondering if towns with less AC and whitewashed or mud-brown buildings behave differently.

Sep 19, 2016 at 9:30 AM | Unregistered CommenterACK

Perhaps not so wrong after all

"Cities located in forested regions, such as the northeastern United States, also have stronger heat islands than cities situated in grassy or desert environments."

"Cities in desert regions, such as Las Vegas, in contrast, often have weak heat islands or are actually cooler than the surrounding rural area."

Sep 19, 2016 at 10:46 AM | Unregistered CommenterACK

"the suburban areas around desert cities are actually cooler than both the city center and the outer rural areas because the irrigation of lawns and small farms leads to more moisture in the air from plants that would not naturally grow in the region."

Apparently the UHI is always reported as the temperature difference between the urban centre and the surrounding rural areas. The urban centre is more likely to have less water or vegetation than the suburbs. It occurs to me that this gives both sceptics and the consensuals opportunities to support their views.

The link makes the important point that the magnitude of the UHI is dependent on the nature of the surrounding countryside, with cities surrounded by forests displaying the greater temperature differences. Another possibility to manipulate the evidence. Most of the forests of China have disappeared. Does this affect the UHIs reported for Chinese cities?

Sep 19, 2016 at 12:10 PM | Unregistered CommenterACK

ACK 9:30, 10:46, 12:10

A report from NASA trying to discount UHI is not something I would trust, but my observations and comments .....

A forest canopy must provide more stable (ie less up and down) air temperatures over any 24 hour period, than any grassland, rock, desert, tarmac or concrete. The sea around our coasts does the same, hence sea-land and land-sea breezes.

Forest cover will also increase transpiration from plants, providing a cooling effect, as per urban fountains etc.

Glider pilots are always searching for uplifting thermals. Wheat fields in summer are a favourite. In the UK, I am not sure they are allowed to circle over towns and cities. But if a wheat field can create an updraught, it must be pulling cooler and denser air in from somewhere else.

The logical conclusion for climate recording purposes, is that thermometers in built up areas are not reliable. Even a thermometer in the middle of Regents Park, London, or Central Park New York can not be deemed to be outside the influence of man's activities or effects. Thermometers in rural areas are going to be effected by the crops grown in adjacent fields, especially when in the UK we have high pressure, and sunnier windless conditions.

Sep 19, 2016 at 2:46 PM | Unregistered Commentergolf charlie

golfCharlie. I did not get the impression that the two NASA sites I linked to were trying to deny UHI. Far from it, the authors were using satellite imagery to explain the phenomenon and to explain why it differs in different cities. I found them very informative.

Sep 19, 2016 at 3:26 PM | Unregistered CommenterACK

ACK 3:26, point taken, but in that case why are temperatures from within UHIs still featuring in the mythical average temperatures of the globe?

Jones et al 1990 set out to prove that UHI was NOT a factor in recorded temperatures having risen, and climate scientists have relied on it ever since. Why have these "findings" from satellite imagery techniques not found their way into published science and challenged Jones et al?

Sep 19, 2016 at 3:55 PM | Unregistered Commentergolf charlie

golfCharlie. Don't know. Perhaps satellite data of surface temperatures cannot be calebrated well enough to be useful. I have no idea why climate science does many of the things it does.

Sep 19, 2016 at 4:18 PM | Unregistered CommenterACK

One thing I've wondered about, and can't find the answer, is whether or not the satellite series were calibrated partly using Phil Jones's phony UHI data.

Sep 19, 2016 at 4:22 PM | Unregistered Commenterkim

kim, nobody knows if the Jones data was phoney, because it has never been found, to ascerain whether anything of value was ever lost.. The Jones et al 1990 conclusions should certainly be "revisited", in light of the satellite findings highlighted by ACK.

If the Satellite data was published in a formal paper, it might cause some of Jones et al 1990 to be revisited, and it's importance would then be lost to Climate Science. Of course a lot of Climate Science would be lost without Jones et al 1990. Climate Science does seem to depend on everyone else being kept in the dark. If you shine a light at it, it's not really there at all.

Why is climate science so frightened of FOI? Answers please to the Prime Minister.

Sep 19, 2016 at 5:30 PM | Unregistered Commentergolf charlie

Anyone who cycles in winter and travels between ural and urban, in cold weather, should know well about the UHI...

Sep 19, 2016 at 7:27 PM | Unregistered CommenterCyclist

Cyclist, agreed, the urals are very cold in winter.

Sep 19, 2016 at 10:22 PM | Unregistered Commentergolf charlie

@AK, Sep 17, 2016 at 11:56 AM

It has just occurred to me that desert towns may exhibit a reverse UHI effect, since they may have more vegetation and exposed water surfaces than the surrounding desert. It would explain why gardens and water features are present in former arab towns and cities in southern Spain. They constitute cooler areas, not just because they are shaded.

Just occurred to you? You are a retired UEA academic. Shows how detached you academics are from real world. You all need to leave your ivory towers and look around more to understand reality.

Sep 20, 2016 at 12:47 AM | Registered CommenterPcar